meson/mesonbuild/interpreter.py

# Copyright 2012-2016 The Meson development team

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from . import mparser
from . import environment
from . import coredata
from . import dependencies
from . import mlog
from . import build
from . import optinterpreter
from . import compilers
from .wrap import wrap
from . import mesonlib

import os, sys, platform, subprocess, shutil, uuid, re
from functools import wraps

import importlib

class InterpreterException(mesonlib.MesonException):
    pass

class InvalidCode(InterpreterException):
    pass

class InvalidArguments(InterpreterException):
    pass

# Decorators for method calls.

def check_stringlist(a, msg='Arguments must be strings.'):
    if not isinstance(a, list):
        mlog.debug('Not a list:', str(a))
        raise InvalidArguments('Argument not a list.')
    if not all(isinstance(s, str) for s in a):
        mlog.debug('Element not a string:', str(a))
        raise InvalidArguments(msg)

def noPosargs(f):
    @wraps(f)
    def wrapped(self, node, args, kwargs):
        if len(args) != 0:
            raise InvalidArguments('Function does not take positional arguments.')
        return f(self, node, args, kwargs)
    return wrapped

def noKwargs(f):
    @wraps(f)
    def wrapped(self, node, args, kwargs):
        if len(kwargs) != 0:
            raise InvalidArguments('Function does not take keyword arguments.')
        return f(self, node, args, kwargs)
    return wrapped

def stringArgs(f):
    @wraps(f)
    def wrapped(self, node, args, kwargs):
        assert(isinstance(args, list))
        check_stringlist(args)
        return f(self, node, args, kwargs)
    return wrapped

def stringifyUserArguments(args):
    if isinstance(args, list):
        return '[%s]' % ', '.join([stringifyUserArguments(x) for x in args])
    elif isinstance(args, int):
        return str(args)
    elif isinstance(args, str):
        return "'%s'" % args
    raise InvalidArguments('Function accepts only strings, integers, lists and lists thereof.')

class InterpreterObject():
    def __init__(self):
        self.methods = {}

    def method_call(self, method_name, args, kwargs):
        if method_name in self.methods:
            return self.methods[method_name](args, kwargs)
        raise InvalidCode('Unknown method "%s" in object.' % method_name)

class TryRunResultHolder(InterpreterObject):
    def __init__(self, res):
        super().__init__()
        self.res = res
        self.methods.update({'returncode' : self.returncode_method,
                             'compiled' : self.compiled_method,
                             'stdout' : self.stdout_method,
                             'stderr' : self.stderr_method,
                            })

    def returncode_method(self, args, kwargs):
        return self.res.returncode

    def compiled_method(self, args, kwargs):
        return self.res.compiled

    def stdout_method(self, args, kwargs):
        return self.res.stdout

    def stderr_method(self, args, kwargs):
        return self.res.stderr

class RunProcess(InterpreterObject):

    def __init__(self, command_array, source_dir, build_dir, subdir, in_builddir=False):
        super().__init__()
        pc = self.run_command(command_array, source_dir, build_dir, subdir, in_builddir)
        (stdout, stderr) = pc.communicate()
        self.returncode = pc.returncode
        self.stdout = stdout.decode().replace('\r\n', '\n')
        self.stderr = stderr.decode().replace('\r\n', '\n')
        self.methods.update({'returncode' : self.returncode_method,
                             'stdout' : self.stdout_method,
                             'stderr' : self.stderr_method,
                            })

    def run_command(self, command_array, source_dir, build_dir, subdir, in_builddir):
        cmd_name = command_array[0]
        env = {'MESON_SOURCE_ROOT' : source_dir,
               'MESON_BUILD_ROOT' : build_dir,
               'MESON_SUBDIR' : subdir}
        if in_builddir:
            cwd = os.path.join(build_dir, subdir)
        else:
            cwd = os.path.join(source_dir, subdir)
        child_env = os.environ.copy()
        child_env.update(env)
        try:
            return subprocess.Popen(command_array, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    env=child_env, cwd=cwd)
        except FileNotFoundError:
            pass
        # Was not a command, is a program in path?
        exe = shutil.which(cmd_name)
        if exe is not None:
            command_array = [exe] + command_array[1:]
            return subprocess.Popen(command_array, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    env=child_env, cwd=cwd)
        # No? Maybe it is a script in the source tree.
        fullpath = os.path.join(source_dir, subdir, cmd_name)
        command_array = [fullpath] + command_array[1:]
        try:
            return subprocess.Popen(command_array, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    env=child_env, cwd=cwd)
        except FileNotFoundError:
            raise InterpreterException('Could not execute command "%s".' % cmd_name)

    def returncode_method(self, args, kwargs):
        return self.returncode

    def stdout_method(self, args, kwargs):
        return self.stdout

    def stderr_method(self, args, kwargs):
        return self.stderr

class ConfigureFileHolder(InterpreterObject):

    def __init__(self, subdir, sourcename, targetname, configuration_data):
        InterpreterObject.__init__(self)
        self.held_object = build.ConfigureFile(subdir, sourcename, targetname, configuration_data)

class ConfigurationDataHolder(InterpreterObject):
    def __init__(self):
        super().__init__()
        self.used = False # These objects become immutable after use in configure_file.
        self.held_object = build.ConfigurationData()
        self.methods.update({'set': self.set_method,
                             'set10': self.set10_method,
                             'has' : self.has_method,
                            })

    def is_used(self):
        return self.used

    def mark_used(self):
        self.used = True

    def validate_args(self, args):
        if len(args) != 2:
            raise InterpreterException("Configuration set requires 2 arguments.")
        if self.used:
            raise InterpreterException("Can not set values on configuration object that has been used.")
        name = args[0]
        val = args[1]
        if not isinstance(name, str):
            raise InterpreterException("First argument to set must be a string.")
        return (name, val)

    def set_method(self, args, kwargs):
        (name, val) = self.validate_args(args)
        self.held_object.values[name] = val

    def set10_method(self, args, kwargs):
        (name, val) = self.validate_args(args)
        if val:
            self.held_object.values[name] = 1
        else:
            self.held_object.values[name] = 0

    def has_method(self, args, kwargs):
        return args[0] in self.held_object.values

    def get(self, name):
        return self.held_object.values[name]

    def keys(self):
        return self.held_object.values.keys()

# Interpreter objects can not be pickled so we must have
# these wrappers.

class DependencyHolder(InterpreterObject):
    def __init__(self, dep):
        InterpreterObject.__init__(self)
        self.held_object = dep
        self.methods.update({'found' : self.found_method,
                             'version': self.version_method})

    def found_method(self, args, kwargs):
        return self.held_object.found()

    def version_method(self, args, kwargs):
        return self.held_object.get_version()

class InternalDependencyHolder(InterpreterObject):
    def __init__(self, dep):
        InterpreterObject.__init__(self)
        self.held_object = dep
        self.methods.update({'found' : self.found_method,
                             'version': self.version_method,
                             })

    def found_method(self, args, kwargs):
        return True

    def version_method(self, args, kwargs):
        return self.held_object.get_version()

class ExternalProgramHolder(InterpreterObject):
    def __init__(self, ep):
        InterpreterObject.__init__(self)
        self.held_object = ep
        self.methods.update({'found': self.found_method,
                             'path': self.path_method})

    def found_method(self, args, kwargs):
        return self.found()

    def path_method(self, args, kwargs):
        return self.get_command()

    def found(self):
        return self.held_object.found()

    def get_command(self):
        return self.held_object.fullpath

    def get_name(self):
        return self.held_object.name

class ExternalLibraryHolder(InterpreterObject):
    def __init__(self, el):
        InterpreterObject.__init__(self)
        self.held_object = el
        self.methods.update({'found': self.found_method})

    def found(self):
        return self.held_object.found()

    def found_method(self, args, kwargs):
        return self.found()

    def get_filename(self):
        return self.held_object.fullpath

    def get_name(self):
        return self.held_object.name

    def get_compile_args(self):
        return self.held_object.get_compile_args()

    def get_link_args(self):
        return self.held_object.get_link_args()

    def get_exe_args(self):
        return self.held_object.get_exe_args()

class GeneratorHolder(InterpreterObject):
    def __init__(self, interpreter, args, kwargs):
        super().__init__()
        self.interpreter = interpreter
        self.held_object = build.Generator(args, kwargs)
        self.methods.update({'process' : self.process_method})

    def process_method(self, args, kwargs):
        check_stringlist(args)
        extras = mesonlib.stringlistify(kwargs.get('extra_args', []))
        gl = GeneratedListHolder(self, extras)
        [gl.add_file(os.path.join(self.interpreter.subdir, a)) for a in args]
        return gl

class GeneratedListHolder(InterpreterObject):
    def __init__(self, arg1, extra_args=[]):
        super().__init__()
        if isinstance(arg1, GeneratorHolder):
            self.held_object = build.GeneratedList(arg1.held_object, extra_args)
        else:
            self.held_object = arg1

    def add_file(self, a):
        self.held_object.add_file(a)

class BuildMachine(InterpreterObject):
    def __init__(self):
        InterpreterObject.__init__(self)
        self.methods.update({'system' : self.system_method,
                             'cpu_family' : self.cpu_family_method,
                             'cpu' : self.cpu_method,
                             'endian' : self.endian_method,
                            })

    def cpu_family_method(self, args, kwargs):
        return environment.detect_cpu_family()

    def cpu_method(self, args, kwargs):
        return environment.detect_cpu()

    def system_method(self, args, kwargs):
        return environment.detect_system()

    def endian_method(self, args, kwargs):
        return sys.byteorder

# This class will provide both host_machine and
# target_machine
class CrossMachineInfo(InterpreterObject):
    def __init__(self, cross_info):
        InterpreterObject.__init__(self)
        minimum_cross_info = {'cpu', 'cpu_family', 'endian', 'system'}
        if set(cross_info) < minimum_cross_info:
            raise InterpreterException(
                'Machine info is currently {}\n'.format(cross_info) +
                'but is missing {}.'.format(minimum_cross_info - set(cross_info)))
        self.info = cross_info
        self.methods.update({'system' : self.system_method,
                             'cpu' : self.cpu_method,
                             'cpu_family' : self.cpu_family_method,
                             'endian' : self.endian_method,
                            })

    def system_method(self, args, kwargs):
        return self.info['system']

    def cpu_method(self, args, kwargs):
        return self.info['cpu']

    def cpu_family_method(self, args, kwargs):
        return self.info['cpu_family']

    def endian_method(self, args, kwargs):
        return self.info['endian']

class IncludeDirsHolder(InterpreterObject):
    def __init__(self, idobj):
        super().__init__()
        self.held_object = idobj

class Headers(InterpreterObject):

    def __init__(self, src_subdir, sources, kwargs):
        InterpreterObject.__init__(self)
        self.sources = sources
        self.source_subdir = src_subdir
        self.install_subdir = kwargs.get('subdir', '')
        self.custom_install_dir = kwargs.get('install_dir', None)
        if self.custom_install_dir is not None:
            if not isinstance(self.custom_install_dir, str):
                raise InterpreterException('Custom_install_dir must be a string.')

    def set_install_subdir(self, subdir):
        self.install_subdir = subdir

    def get_install_subdir(self):
        return self.install_subdir

    def get_source_subdir(self):
        return self.source_subdir

    def get_sources(self):
        return self.sources

    def get_custom_install_dir(self):
        return self.custom_install_dir

class DataHolder(InterpreterObject):
    def __init__(self, in_sourcetree, source_subdir, sources, kwargs):
        super().__init__()
        kwsource = mesonlib.stringlistify(kwargs.get('sources', []))
        sources += kwsource
        check_stringlist(sources)
        install_dir = kwargs.get('install_dir', None)
        if not isinstance(install_dir, str):
            raise InterpreterException('Custom_install_dir must be a string.')
        self.held_object = build.Data(in_sourcetree, source_subdir, sources, install_dir)

    def get_source_subdir(self):
        return self.held_object.source_subdir

    def get_sources(self):
        return self.held_object.sources

    def get_install_dir(self):
        return self.held_object.install_dir

class InstallDir(InterpreterObject):
    def __init__(self, source_subdir, installable_subdir, install_dir):
        InterpreterObject.__init__(self)
        self.source_subdir = source_subdir
        self.installable_subdir = installable_subdir
        self.install_dir = install_dir

class Man(InterpreterObject):

    def __init__(self, source_subdir, sources, kwargs):
        InterpreterObject.__init__(self)
        self.source_subdir = source_subdir
        self.sources = sources
        self.validate_sources()
        if len(kwargs) > 1:
            raise InvalidArguments('Man function takes at most one keyword arguments.')
        self.custom_install_dir = kwargs.get('install_dir', None)
        if self.custom_install_dir is not None and not isinstance(self.custom_install_dir, str):
            raise InterpreterException('Custom_install_dir must be a string.')

    def validate_sources(self):
        for s in self.sources:
            num = int(s.split('.')[-1])
            if num < 1 or num > 8:
                raise InvalidArguments('Man file must have a file extension of a number between 1 and 8')

    def get_custom_install_dir(self):
        return self.custom_install_dir

    def get_sources(self):
        return self.sources

    def get_source_subdir(self):
        return self.source_subdir

class GeneratedObjectsHolder(InterpreterObject):
    def __init__(self, held_object):
        super().__init__()
        self.held_object = held_object

class BuildTargetHolder(InterpreterObject):
    def __init__(self, target, interp):
        super().__init__()
        self.held_object = target
        self.interpreter = interp
        self.methods.update({'extract_objects' : self.extract_objects_method,
                             'extract_all_objects' : self.extract_all_objects_method,
                             'get_id': self.get_id_method,
                             'outdir' : self.outdir_method,
                             'private_dir_include' : self.private_dir_include_method,
                             })

    def is_cross(self):
        return self.held_object.is_cross()

    def private_dir_include_method(self, args, kwargs):
        return IncludeDirsHolder(build.IncludeDirs('', [], False,
                    [self.interpreter.backend.get_target_private_dir(self.held_object)]))

    def outdir_method(self, args, kwargs):
        return self.interpreter.backend.get_target_dir(self.held_object)

    def extract_objects_method(self, args, kwargs):
        gobjs = self.held_object.extract_objects(args)
        return GeneratedObjectsHolder(gobjs)

    def extract_all_objects_method(self, args, kwargs):
        gobjs = self.held_object.extract_all_objects()
        return GeneratedObjectsHolder(gobjs)

    def get_id_method(self, args, kwargs):
        return self.held_object.get_id()

class ExecutableHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class StaticLibraryHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class SharedLibraryHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class JarHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class CustomTargetHolder(InterpreterObject):
    def __init__(self, object_to_hold):
        self.held_object = object_to_hold

    def is_cross(self):
        return self.held_object.is_cross()

    def extract_objects_method(self, args, kwargs):
        gobjs = self.held_object.extract_objects(args)
        return GeneratedObjectsHolder(gobjs)

class RunTargetHolder(InterpreterObject):
    def __init__(self, name, command, args, subdir):
        self.held_object = build.RunTarget(name, command, args, subdir)

class Test(InterpreterObject):
    def __init__(self, name, suite, exe, is_parallel, cmd_args, env, should_fail, valgrind_args, timeout, workdir):
        InterpreterObject.__init__(self)
        self.name = name
        self.suite = suite
        self.exe = exe
        self.is_parallel = is_parallel
        self.cmd_args = cmd_args
        self.env = env
        self.should_fail = should_fail
        self.valgrind_args = valgrind_args
        self.timeout = timeout
        self.workdir = workdir

    def get_exe(self):
        return self.exe

    def get_name(self):
        return self.name

class SubprojectHolder(InterpreterObject):

    def __init__(self, subinterpreter):
        super().__init__()
        self.subinterpreter = subinterpreter
        self.methods.update({'get_variable' : self.get_variable_method,
                            })

    def get_variable_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Get_variable takes one argument.')
        varname = args[0]
        if not isinstance(varname, str):
            raise InterpreterException('Get_variable takes a string argument.')
        return self.subinterpreter.variables[varname]

class CompilerHolder(InterpreterObject):
    def __init__(self, compiler, env):
        InterpreterObject.__init__(self)
        self.compiler = compiler
        self.environment = env
        self.methods.update({'compiles': self.compiles_method,
                             'links': self.links_method,
                             'get_id': self.get_id_method,
                             'sizeof': self.sizeof_method,
                             'has_header': self.has_header_method,
                             'has_header_symbol': self.has_header_symbol_method,
                             'run' : self.run_method,
                             'has_function' : self.has_function_method,
                             'has_member' : self.has_member_method,
                             'has_type' : self.has_type_method,
                             'alignment' : self.alignment_method,
                             'version' : self.version_method,
                             'cmd_array' : self.cmd_array_method,
                             'find_library': self.find_library_method,
                            })

    def version_method(self, args, kwargs):
        return self.compiler.version

    def cmd_array_method(self, args, kwargs):
        return self.compiler.exelist

    def determine_args(self, kwargs):
        nobuiltins = kwargs.get('no_builtin_args', False)
        if not isinstance(nobuiltins, bool):
            raise InterpreterException('Type of no_builtin_args not a boolean.')
        args = []
        if not nobuiltins:
            opts = self.environment.coredata.compiler_options
            args += self.compiler.get_option_compile_args(opts)
            args += self.compiler.get_option_link_args(opts)
        args += mesonlib.stringlistify(kwargs.get('args', []))
        return args

    def alignment_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Alignment method takes exactly one positional argument.')
        check_stringlist(args)
        typename = args[0]
        extra_args = mesonlib.stringlistify(kwargs.get('args', []))
        result = self.compiler.alignment(typename, self.environment, extra_args)
        mlog.log('Checking for alignment of "', mlog.bold(typename), '": ', result, sep='')
        return result

    def run_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Run method takes exactly one positional argument.')
        check_stringlist(args)
        code = args[0]
        testname = kwargs.get('name', '')
        if not isinstance(testname, str):
            raise InterpreterException('Testname argument must be a string.')
        extra_args = self.determine_args(kwargs)
        result = self.compiler.run(code, extra_args)
        if len(testname) > 0:
            if not result.compiled:
                h = mlog.red('DID NOT COMPILE')
            elif result.returncode == 0:
                h = mlog.green('YES')
            else:
                h = mlog.red('NO (%d)' % result.returncode)
            mlog.log('Checking if "', mlog.bold(testname), '" runs : ', h, sep='')
        return TryRunResultHolder(result)

    def get_id_method(self, args, kwargs):
        return self.compiler.get_id()

    def has_member_method(self, args, kwargs):
        if len(args) != 2:
            raise InterpreterException('Has_member takes exactly two arguments.')
        check_stringlist(args)
        typename = args[0]
        membername = args[1]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_function must be a string.')
        extra_args = self.determine_args(kwargs)
        had = self.compiler.has_member(typename, membername, prefix, extra_args)
        if had:
            hadtxt = mlog.green('YES')
        else:
            hadtxt = mlog.red('NO')
        mlog.log('Checking whether type "', mlog.bold(typename),
                 '" has member "', mlog.bold(membername), '": ', hadtxt, sep='')
        return had

    def has_function_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Has_function takes exactly one argument.')
        check_stringlist(args)
        funcname = args[0]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_function must be a string.')
        extra_args = self.determine_args(kwargs)
        had = self.compiler.has_function(funcname, prefix, self.environment, extra_args)
        if had:
            hadtxt = mlog.green('YES')
        else:
            hadtxt = mlog.red('NO')
        mlog.log('Checking for function "', mlog.bold(funcname), '": ', hadtxt, sep='')
        return had

    def has_type_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Has_type takes exactly one argument.')
        check_stringlist(args)
        typename = args[0]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_type must be a string.')
        extra_args = self.determine_args(kwargs)
        had = self.compiler.has_type(typename, prefix, extra_args)
        if had:
            hadtxt = mlog.green('YES')
        else:
            hadtxt = mlog.red('NO')
        mlog.log('Checking for type "', mlog.bold(typename), '": ', hadtxt, sep='')
        return had

    def sizeof_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Sizeof takes exactly one argument.')
        check_stringlist(args)
        element = args[0]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of sizeof must be a string.')
        extra_args = self.determine_args(kwargs)
        esize = self.compiler.sizeof(element, prefix, self.environment, extra_args)
        mlog.log('Checking for size of "%s": %d' % (element, esize))
        return esize

    def compiles_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('compiles method takes exactly one argument.')
        check_stringlist(args)
        code = args[0]
        testname = kwargs.get('name', '')
        if not isinstance(testname, str):
            raise InterpreterException('Testname argument must be a string.')
        extra_args = self.determine_args(kwargs)
        result = self.compiler.compiles(code, extra_args)
        if len(testname) > 0:
            if result:
                h = mlog.green('YES')
            else:
                h = mlog.red('NO')
            mlog.log('Checking if "', mlog.bold(testname), '" compiles : ', h, sep='')
        return result

    def links_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('links method takes exactly one argument.')
        check_stringlist(args)
        code = args[0]
        testname = kwargs.get('name', '')
        if not isinstance(testname, str):
            raise InterpreterException('Testname argument must be a string.')
        extra_args = self.determine_args(kwargs)
        result = self.compiler.links(code, extra_args)
        if len(testname) > 0:
            if result:
                h = mlog.green('YES')
            else:
                h = mlog.red('NO')
            mlog.log('Checking if "', mlog.bold(testname), '" links : ', h, sep='')
        return result

    def has_header_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('has_header method takes exactly one argument.')
        check_stringlist(args)
        string = args[0]
        extra_args = self.determine_args(kwargs)
        haz = self.compiler.has_header(string, extra_args)
        if haz:
            h = mlog.green('YES')
        else:
            h = mlog.red('NO')
        mlog.log('Has header "%s":' % string, h)
        return haz

    def has_header_symbol_method(self, args, kwargs):
        if len(args) != 2:
            raise InterpreterException('has_header_symbol method takes exactly two arguments.')
        check_stringlist(args)
        hname = args[0]
        symbol = args[1]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_function must be a string.')
        extra_args = self.determine_args(kwargs)
        haz = self.compiler.has_header_symbol(hname, symbol, prefix, extra_args)
        if haz:
            h = mlog.green('YES')
        else:
            h = mlog.red('NO')
        mlog.log('Header <{0}> has symbol "{1}":'.format(hname, symbol), h)
        return haz

    def find_library_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('find_library method takes one argument.')
        libname = args[0]
        if not isinstance(libname, str):
            raise InterpreterException('Library name not a string.')
        required = kwargs.get('required', True)
        if not isinstance(required, bool):
            raise InterpreterException('required must be boolean.')
        search_dirs = mesonlib.stringlistify(kwargs.get('dirs', []))
        for i in search_dirs:
            if not os.path.isabs(i):
                raise InvalidCode('Search directory %s is not an absolute path.' % i)
        linkargs = self.compiler.find_library(libname, search_dirs)
        if required and linkargs is None:
            raise InterpreterException('Library {} not found'.format(libname))
        lib = dependencies.ExternalLibrary(libname, linkargs)
        return ExternalLibraryHolder(lib)

class ModuleState:
    pass

class ModuleHolder(InterpreterObject):
    def __init__(self, modname, module, interpreter):
        InterpreterObject.__init__(self)
        self.modname = modname
        self.held_object = module
        self.interpreter = interpreter

    def method_call(self, method_name, args, kwargs):
        try:
            fn = getattr(self.held_object, method_name)
        except AttributeError:
            raise InvalidArguments('Module %s does not have method %s.' % (self.modname, method_name))
        state = ModuleState()
        state.build_to_src = os.path.relpath(self.interpreter.environment.get_source_dir(),
                                             self.interpreter.environment.get_build_dir())
        state.subdir = self.interpreter.subdir
        state.environment = self.interpreter.environment
        state.project_name = self.interpreter.build.project_name
        state.project_version = self.interpreter.build.dep_manifest[self.interpreter.active_projectname]
        state.compilers = self.interpreter.build.compilers
        state.targets = self.interpreter.build.targets
        state.headers = self.interpreter.build.get_headers()
        state.man = self.interpreter.build.get_man()
        state.global_args = self.interpreter.build.global_args
        value = fn(state, args, kwargs)
        return self.interpreter.module_method_callback(value)

class MesonMain(InterpreterObject):
    def __init__(self, build, interpreter):
        InterpreterObject.__init__(self)
        self.build = build
        self.interpreter = interpreter
        self.methods.update({'get_compiler': self.get_compiler_method,
                             'is_cross_build' : self.is_cross_build_method,
                             'has_exe_wrapper' : self.has_exe_wrapper_method,
                             'is_unity' : self.is_unity_method,
                             'is_subproject' : self.is_subproject_method,
                             'current_source_dir' : self.current_source_dir_method,
                             'current_build_dir' : self.current_build_dir_method,
                             'source_root' : self.source_root_method,
                             'build_root' : self.build_root_method,
                             'add_install_script' : self.add_install_script_method,
                             'add_postconf_script' : self.add_postconf_script_method,
                             'install_dependency_manifest': self.install_dependency_manifest_method,
                             'project_version': self.project_version_method,
                            })

    def add_install_script_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Set_install_script takes exactly one argument.')
        check_stringlist(args)
        scriptbase = args[0]
        scriptfile = os.path.join(self.interpreter.environment.source_dir,
                                  self.interpreter.subdir, scriptbase)
        if not os.path.isfile(scriptfile):
            raise InterpreterException('Can not find install script %s.' % scriptbase)
        self.build.install_scripts.append(build.InstallScript([scriptfile]))

    def add_postconf_script_method(self, args, kwargs):
        if len(args) < 1:
            raise InterpreterException('Not enough arguments')
        check_stringlist(args, 'add_postconf_script arguments must be strings.')
        scriptbase = args[0]
        search_dir = os.path.join(self.interpreter.environment.source_dir,
                                  self.interpreter.subdir)
        exe = dependencies.ExternalProgram(scriptbase, search_dir=search_dir)
        extras = args[1:]
        self.build.postconf_scripts.append({'exe': exe, 'args': extras})

    def current_source_dir_method(self, args, kwargs):
        src = self.interpreter.environment.source_dir
        sub = self.interpreter.subdir
        if sub == '':
            return src
        return os.path.join(src, sub)

    def current_build_dir_method(self, args, kwargs):
        src = self.interpreter.environment.build_dir
        sub = self.interpreter.subdir
        if sub == '':
            return src
        return os.path.join(src, sub)

    def source_root_method(self, args, kwargs):
        return self.interpreter.environment.source_dir

    def build_root_method(self, args, kwargs):
        return self.interpreter.environment.build_dir

    def has_exe_wrapper_method(self, args, kwargs):
        if self.is_cross_build_method(None, None) and \
           'binaries' in self.build.environment.cross_info.config and \
           self.build.environment.cross_info.need_exe_wrapper():
            exe_wrap = self.build.environment.cross_info.config['binaries'].get('exe_wrapper', None)
            if exe_wrap is None:
                return False
        # We return True when exe_wrap is defined, when it's not needed, and
        # when we're compiling natively. The last two are semantically confusing.
        # Need to revisit this.
        return True

    def is_cross_build_method(self, args, kwargs):
        return self.build.environment.is_cross_build()

    def get_compiler_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('get_compiler_method must have one and only one argument.')
        cname = args[0]
        native = kwargs.get('native', None)
        if native is None:
            if self.build.environment.is_cross_build():
                native = False
            else:
                native = True
        if not isinstance(native, bool):
            raise InterpreterException('Type of "native" must be a boolean.')
        if native:
            clist = self.build.compilers
        else:
            clist = self.build.cross_compilers
        for c in clist:
            if c.get_language() == cname:
                return CompilerHolder(c, self.build.environment)
        raise InterpreterException('Tried to access compiler for unspecified language "%s".' % cname)

    def is_unity_method(self, args, kwargs):
        return self.build.environment.coredata.get_builtin_option('unity')

    def is_subproject_method(self, args, kwargs):
        return self.interpreter.is_subproject()

    def install_dependency_manifest_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Must specify manifest install file name')
        if not isinstance(args[0], str):
            raise InterpreterException('Argument must be a string.')
        self.build.dep_manifest_name = args[0]

    def project_version_method(self, args, kwargs):
        return self.build.dep_manifest[self.interpreter.active_projectname]['version']

class Interpreter():

    def __init__(self, build, backend, subproject='', subdir='', subproject_dir='subprojects'):
        self.build = build
        self.backend = backend
        self.subproject = subproject
        self.subdir = subdir
        self.source_root = build.environment.get_source_dir()
        self.subproject_dir = subproject_dir
        option_file = os.path.join(self.source_root, self.subdir, 'meson_options.txt')
        if os.path.exists(option_file):
            oi = optinterpreter.OptionInterpreter(self.subproject, \
                                                  self.build.environment.cmd_line_options.projectoptions)
            oi.process(option_file)
            self.build.environment.merge_options(oi.options)
        mesonfile = os.path.join(self.source_root, self.subdir, environment.build_filename)
        if not os.path.isfile(mesonfile):
            raise InvalidArguments('Missing Meson file in %s' % mesonfile)
        code = open(mesonfile, encoding='utf8').read()
        if len(code.strip()) == 0:
            raise InvalidCode('Builder file is empty.')
        assert(isinstance(code, str))
        try:
            self.ast = mparser.Parser(code).parse()
        except mesonlib.MesonException as me:
            me.file = environment.build_filename
            raise me
        self.sanity_check_ast()
        self.variables = {}
        self.builtin = {}
        self.builtin['build_machine'] = BuildMachine()
        if not self.build.environment.is_cross_build():
            self.builtin['host_machine'] = self.builtin['build_machine']
            self.builtin['target_machine'] = self.builtin['build_machine']
        else:
            cross_info = self.build.environment.cross_info
            if cross_info.has_host():
                self.builtin['host_machine'] = CrossMachineInfo(cross_info.config['host_machine'])
            else:
                self.builtin['host_machine'] = self.builtin['build_machine']
            if cross_info.has_target():
                self.builtin['target_machine'] = CrossMachineInfo(cross_info.config['target_machine'])
            else:
                self.builtin['target_machine'] = self.builtin['host_machine']
        self.builtin['meson'] = MesonMain(build, self)
        self.environment = build.environment
        self.build_func_dict()
        self.build_def_files = [os.path.join(self.subdir, environment.build_filename)]
        self.coredata = self.environment.get_coredata()
        self.generators = []
        self.visited_subdirs = {}
        self.global_args_frozen = False
        self.subprojects = {}
        self.subproject_stack = []

    def build_func_dict(self):
        self.funcs = {'project' : self.func_project,
                      'message' : self.func_message,
                      'error' : self.func_error,
                      'executable': self.func_executable,
                      'dependency' : self.func_dependency,
                      'static_library' : self.func_static_lib,
                      'shared_library' : self.func_shared_lib,
                      'library' : self.func_library,
                      'jar' : self.func_jar,
                      'build_target': self.func_build_target,
                      'custom_target' : self.func_custom_target,
                      'run_target' : self.func_run_target,
                      'generator' : self.func_generator,
                      'test' : self.func_test,
                      'benchmark' : self.func_benchmark,
                      'install_headers' : self.func_install_headers,
                      'install_man' : self.func_install_man,
                      'subdir' : self.func_subdir,
                      'install_data' : self.func_install_data,
                      'install_subdir' : self.func_install_subdir,
                      'configure_file' : self.func_configure_file,
                      'include_directories' : self.func_include_directories,
                      'add_global_arguments' : self.func_add_global_arguments,
                      'add_global_link_arguments' : self.func_add_global_link_arguments,
                      'add_languages' : self.func_add_languages,
                      'find_program' : self.func_find_program,
                      'find_library' : self.func_find_library,
                      'configuration_data' : self.func_configuration_data,
                      'run_command' : self.func_run_command,
                      'gettext' : self.func_gettext,
                      'option' : self.func_option,
                      'get_option' : self.func_get_option,
                      'subproject' : self.func_subproject,
                      'vcs_tag' : self.func_vcs_tag,
                      'set_variable' : self.func_set_variable,
                      'is_variable' : self.func_is_variable,
                      'get_variable' : self.func_get_variable,
                      'import' : self.func_import,
                      'files' : self.func_files,
                      'declare_dependency': self.func_declare_dependency,
                      'assert': self.func_assert,
                     }

    def module_method_callback(self, invalues):
        unwrap_single = False
        if invalues is None:
            return
        if not isinstance(invalues, list):
            unwrap_single = True
            invalues = [invalues]
        outvalues = []
        for v in invalues:
            if isinstance(v, build.CustomTarget):
                if v.name in self.build.targets:
                    raise InterpreterException('Tried to create target %s which already exists.' % v.name)
                self.build.targets[v.name] = v
                outvalues.append(CustomTargetHolder(v))
            elif isinstance(v, int) or isinstance(v, str):
                outvalues.append(v)
            elif isinstance(v, build.Executable):
                if v.name in self.build.targets:
                    raise InterpreterException('Tried to create target %s which already exists.' % v.name)
                self.build.targets[v.name] = v
                outvalues.append(ExecutableHolder(v))
            elif isinstance(v, list):
                outvalues.append(self.module_method_callback(v))
            elif isinstance(v, build.GeneratedList):
                outvalues.append(GeneratedListHolder(v))
            elif isinstance(v, build.RunTarget):
                if v.name in self.build.targets:
                    raise InterpreterException('Tried to create target %s which already exists.' % v.name)
                self.build.targets[v.name] = v
            elif isinstance(v, build.InstallScript):
                self.build.install_scripts.append(v)
            elif isinstance(v, build.Data):
                self.build.data.append(v)
            else:
                print(v)
                raise InterpreterException('Module returned a value of unknown type.')
        if len(outvalues) == 1 and unwrap_single:
            return outvalues[0]
        return outvalues

    def get_build_def_files(self):
        return self.build_def_files

    def get_variables(self):
        return self.variables

    def sanity_check_ast(self):
        if not isinstance(self.ast, mparser.CodeBlockNode):
            raise InvalidCode('AST is of invalid type. Possibly a bug in the parser.')
        if len(self.ast.lines) == 0:
            raise InvalidCode('No statements in code.')
        first = self.ast.lines[0]
        if not isinstance(first, mparser.FunctionNode) or first.func_name != 'project':
            raise InvalidCode('First statement must be a call to project')

    def check_cross_stdlibs(self):
        if self.build.environment.is_cross_build():
            cross_info = self.build.environment.cross_info
            for c in self.build.cross_compilers:
                l = c.language
                try:
                    di = mesonlib.stringlistify(cross_info.get_stdlib(l))
                    if len(di) != 2:
                        raise InterpreterException('Stdlib definition for %s should have exactly two elements.' \
                                                   % l)
                    projname, depname = di
                    subproj = self.do_subproject(projname, {})
                    self.build.cross_stdlibs[l] = subproj.get_variable_method([depname], {})
                except KeyError as e:
                    pass

    def run(self):
        self.evaluate_codeblock(self.ast)
        mlog.log('Build targets in project:', mlog.bold(str(len(self.build.targets))))

    def evaluate_codeblock(self, node):
        if node is None:
            return
        if not isinstance(node, mparser.CodeBlockNode):
            e = InvalidCode('Tried to execute a non-codeblock. Possibly a bug in the parser.')
            e.lineno = node.lineno
            e.colno = node.colno
            raise e
        statements = node.lines
        i = 0
        while i < len(statements):
            cur = statements[i]
            try:
                self.evaluate_statement(cur)
            except Exception as e:
                if not(hasattr(e, 'lineno')):
                    e.lineno = cur.lineno
                    e.colno = cur.colno
                    e.file = os.path.join(self.subdir, 'meson.build')
                raise e
            i += 1 # In THE FUTURE jump over blocks and stuff.

    def get_variable(self, varname):
        if varname in self.builtin:
            return self.builtin[varname]
        if varname in self.variables:
            return self.variables[varname]
        raise InvalidCode('Unknown variable "%s".' % varname)

    def func_set_variable(self, node, args, kwargs):
        if len(args) != 2:
            raise InvalidCode('Set_variable takes two arguments.')
        varname = args[0]
        value = self.to_native(args[1])
        self.set_variable(varname, value)

    @noKwargs
    def func_get_variable(self, node, args, kwargs):
        if len(args)<1 or len(args)>2:
            raise InvalidCode('Get_variable takes one or two arguments.')
        varname = args[0]
        if not isinstance(varname, str):
            raise InterpreterException('First argument must be a string.')
        try:
            return self.variables[varname]
        except KeyError:
            pass
        if len(args) == 2:
            return args[1]
        raise InterpreterException('Tried to get unknown variable "%s".' % varname)

    @stringArgs
    @noKwargs
    def func_is_variable(self, node, args, kwargs):
        if len(args) != 1:
            raise InvalidCode('Is_variable takes two arguments.')
        varname = args[0]
        return varname in self.variables

    @stringArgs
    @noKwargs
    def func_import(self, node, args, kwargs):
        if len(args) != 1:
            raise InvalidCode('Import takes one argument.')
        modname = args[0]
        if not modname in self.environment.coredata.modules:
            module = importlib.import_module('mesonbuild.modules.' + modname).initialize()
            self.environment.coredata.modules[modname] = module
        return ModuleHolder(modname, self.environment.coredata.modules[modname], self)

    @stringArgs
    @noKwargs
    def func_files(self, node, args, kwargs):
        return [mesonlib.File.from_source_file(self.environment.source_dir, self.subdir, fname) for fname in args]

    @noPosargs
    def func_declare_dependency(self, node, args, kwargs):
        version = kwargs.get('version', 'undefined')
        if not isinstance(version, str):
            raise InterpreterException('Version must be a string.')
        incs = kwargs.get('include_directories', [])
        if not isinstance(incs, list):
            incs = [incs]
        libs = kwargs.get('link_with', [])
        if not isinstance(libs, list):
            libs = [libs]
        sources = kwargs.get('sources', [])
        if not isinstance(sources, list):
            sources = [sources]
        sources = self.source_strings_to_files(self.flatten(sources))
        deps = kwargs.get('dependencies', [])
        if not isinstance(deps, list):
            deps = [deps]
        compile_args = mesonlib.stringlistify(kwargs.get('compile_args', []))
        link_args = mesonlib.stringlistify(kwargs.get('link_args', []))
        final_deps = []
        for d in deps:
            try:
                d = d.held_object
            except Exception:
                pass
            if not isinstance(d, (dependencies.Dependency, dependencies.ExternalLibrary, dependencies.InternalDependency)):
                raise InterpreterException('Dependencies must be external deps')
            final_deps.append(d)
        dep = dependencies.InternalDependency(version, incs, compile_args, link_args, libs, sources, final_deps)
        return InternalDependencyHolder(dep)

    @noKwargs
    def func_assert(self, node, args, kwargs):
        if len(args) != 2:
            raise InterpreterException('Assert takes exactly two arguments')
        value, message = args
        if not isinstance(value, bool):
            raise InterpreterException('Assert value not bool.')
        if not isinstance(message, str):
            raise InterpreterException('Assert message not a string.')
        if not value:
            raise InterpreterException('Assert failed: ' + message)

    def set_variable(self, varname, variable):
        if variable is None:
            raise InvalidCode('Can not assign None to variable.')
        if not isinstance(varname, str):
            raise InvalidCode('First argument to set_variable must be a string.')
        if not self.is_assignable(variable):
            raise InvalidCode('Assigned value not of assignable type.')
        if re.match('[_a-zA-Z][_0-9a-zA-Z]*$', varname) is None:
            raise InvalidCode('Invalid variable name: ' + varname)
        if varname in self.builtin:
            raise InvalidCode('Tried to overwrite internal variable "%s"' % varname)
        self.variables[varname] = variable

    def evaluate_statement(self, cur):
        if isinstance(cur, mparser.FunctionNode):
            return self.function_call(cur)
        elif isinstance(cur, mparser.AssignmentNode):
            return self.assignment(cur)
        elif isinstance(cur, mparser.MethodNode):
            return self.method_call(cur)
        elif isinstance(cur, mparser.StringNode):
            return cur.value
        elif isinstance(cur, mparser.BooleanNode):
            return cur.value
        elif isinstance(cur, mparser.IfClauseNode):
            return self.evaluate_if(cur)
        elif isinstance(cur, mparser.IdNode):
            return self.get_variable(cur.value)
        elif isinstance(cur, mparser.ComparisonNode):
            return self.evaluate_comparison(cur)
        elif isinstance(cur, mparser.ArrayNode):
            return self.evaluate_arraystatement(cur)
        elif isinstance(cur, mparser.NumberNode):
            return cur.value
        elif isinstance(cur, mparser.AndNode):
            return self.evaluate_andstatement(cur)
        elif isinstance(cur, mparser.OrNode):
            return self.evaluate_orstatement(cur)
        elif isinstance(cur, mparser.NotNode):
            return self.evaluate_notstatement(cur)
        elif isinstance(cur, mparser.UMinusNode):
            return self.evaluate_uminusstatement(cur)
        elif isinstance(cur, mparser.ArithmeticNode):
            return self.evaluate_arithmeticstatement(cur)
        elif isinstance(cur, mparser.ForeachClauseNode):
            return self.evaluate_foreach(cur)
        elif isinstance(cur, mparser.PlusAssignmentNode):
            return self.evaluate_plusassign(cur)
        elif isinstance(cur, mparser.IndexNode):
            return self.evaluate_indexing(cur)
        elif self.is_elementary_type(cur):
            return cur
        else:
            raise InvalidCode("Unknown statement.")

    def validate_arguments(self, args, argcount, arg_types):
        if argcount is not None:
            if argcount != len(args):
                raise InvalidArguments('Expected %d arguments, got %d.' %
                                       (argcount, len(args)))
        for i in range(min(len(args), len(arg_types))):
            wanted = arg_types[i]
            actual = args[i]
            if wanted != None:
                if not isinstance(actual, wanted):
                    raise InvalidArguments('Incorrect argument type.')

    def func_run_command(self, node, args, kwargs):
        if len(args) < 1:
            raise InterpreterException('Not enough arguments')
        cmd = args[0]
        cargs = args[1:]
        if isinstance(cmd, ExternalProgramHolder):
            cmd = cmd.get_command()
        elif isinstance(cmd, str):
            cmd = [cmd]
        else:
            raise InterpreterException('First argument is of incorrect type.')
        check_stringlist(cargs, 'Run_command arguments must be strings.')
        args = cmd + cargs
        in_builddir = kwargs.get('in_builddir', False)
        if not isinstance(in_builddir, bool):
            raise InterpreterException('in_builddir must be boolean.')
        return RunProcess(args, self.environment.source_dir, self.environment.build_dir,
                          self.subdir, in_builddir)

    @stringArgs
    def func_gettext(self, nodes, args, kwargs):
        raise InterpreterException('Gettext() function has been moved to module i18n. Import it and use i18n.gettext() instead')

    def func_option(self, nodes, args, kwargs):
        raise InterpreterException('Tried to call option() in build description file. All options must be in the option file.')

    @stringArgs
    def func_subproject(self, nodes, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Subproject takes exactly one argument')
        dirname = args[0]
        return self.do_subproject(dirname, kwargs)

    def do_subproject(self, dirname, kwargs):
        if self.subdir != '':
            segs = os.path.split(self.subdir)
            if len(segs) != 2 or segs[0] != self.subproject_dir:
                raise InterpreterException('Subprojects must be defined at the root directory.')
        if dirname in self.subproject_stack:
            fullstack = self.subproject_stack + [dirname]
            incpath = ' => '.join(fullstack)
            raise InterpreterException('Recursive include of subprojects: %s.' % incpath)
        if dirname in self.subprojects:
            return self.subprojects[dirname]
        r = wrap.Resolver(os.path.join(self.build.environment.get_source_dir(), self.subproject_dir))
        resolved = r.resolve(dirname)
        if resolved is None:
            raise InterpreterException('Subproject directory does not exist and can not be downloaded.')
        subdir = os.path.join(self.subproject_dir, resolved)
        os.makedirs(os.path.join(self.build.environment.get_build_dir(), subdir), exist_ok=True)
        self.global_args_frozen = True
        mlog.log('\nExecuting subproject ', mlog.bold(dirname), '.\n', sep='')
        subi = Interpreter(self.build, self.backend, dirname, subdir, self.subproject_dir)
        subi.subprojects = self.subprojects

        subi.subproject_stack = self.subproject_stack + [dirname]
        current_active = self.active_projectname
        subi.run()
        if 'version' in kwargs:
            pv = subi.project_version
            wanted = kwargs['version']
            if not mesonlib.version_compare(pv, wanted):
                raise InterpreterException('Subproject %s version is %s but %s required.' % (dirname, pv, wanted))
        self.active_projectname = current_active
        mlog.log('\nSubproject', mlog.bold(dirname), 'finished.')
        self.build.subprojects[dirname] = True
        self.subprojects.update(subi.subprojects)
        self.subprojects[dirname] = SubprojectHolder(subi)
        self.build_def_files += subi.build_def_files
        return self.subprojects[dirname]

    @stringArgs
    @noKwargs
    def func_get_option(self, nodes, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Argument required for get_option.')
        optname = args[0]
        try:
            return self.environment.get_coredata().get_builtin_option(optname)
        except RuntimeError:
            pass
        try:
            return self.environment.coredata.compiler_options[optname].value
        except KeyError:
            pass
        if not coredata.is_builtin_option(optname) and self.is_subproject():
            optname = self.subproject + ':' + optname
        try:
            return self.environment.coredata.user_options[optname].value
        except KeyError:
            pass
        if optname.endswith('_link_args'):
            try:
                lang = optname[:-10]
                return self.coredata.external_link_args[lang]
            except KeyError:
                pass
        if optname.endswith('_args'):
            try:
                lang = optname[:-5]
                return self.coredata.external_args[lang]
            except KeyError:
                pass
        raise InterpreterException('Tried to access unknown option "%s".' % optname)

    @noKwargs
    def func_configuration_data(self, node, args, kwargs):
        if len(args) != 0:
            raise InterpreterException('configuration_data takes no arguments')
        return ConfigurationDataHolder()

    def parse_default_options(self, default_options):
        if not isinstance(default_options, list):
            default_options = [default_options]
        for option in default_options:
            if not isinstance(option, str):
                mlog.debug(option)
                raise InterpreterException('Default options must be strings')
            if '=' not in option:
                raise InterpreterException('All default options must be of type key=value.')
            key, value = option.split('=', 1)
            if coredata.is_builtin_option(key):
                if not self.environment.had_argument_for(key):
                    self.coredata.set_builtin_option(key, value)
                # If this was set on the command line, do not override.
            else:
                newoptions = [option] + self.environment.cmd_line_options.projectoptions
                self.environment.cmd_line_options.projectoptions = newoptions

    @stringArgs
    def func_project(self, node, args, kwargs):
        if len(args) < 2:
            raise InvalidArguments('Not enough arguments to project(). Needs at least the project name and one language')

        if not self.is_subproject():
            self.build.project_name = args[0]
            if self.environment.first_invocation and 'default_options' in kwargs:
                self.parse_default_options(kwargs['default_options'])
        self.active_projectname = args[0]
        self.project_version = kwargs.get('version', 'undefined')
        proj_license = mesonlib.stringlistify(kwargs.get('license', 'unknown'))
        self.build.dep_manifest[args[0]] = {'version': self.project_version,
                                            'license': proj_license}
        if self.subproject in self.build.projects:
            raise InvalidCode('Second call to project().')
        if not self.is_subproject() and 'subproject_dir' in kwargs:
            self.subproject_dir = kwargs['subproject_dir']

        if 'meson_version' in kwargs:
            cv = coredata.version
            pv = kwargs['meson_version']
            if not mesonlib.version_compare(cv, pv):
                raise InterpreterException('Meson version is %s but project requires %s.' % (cv, pv))
        self.build.projects[self.subproject] = args[0]
        mlog.log('Project name: ', mlog.bold(args[0]), sep='')
        self.add_languages(node, args[1:], True)
        langs = self.coredata.compilers.keys()
        if 'vala' in langs:
            if not 'c' in langs:
                raise InterpreterException('Compiling Vala requires C. Add C to your project languages and rerun Meson.')
        if not self.is_subproject():
            self.check_cross_stdlibs()

    @stringArgs
    def func_add_languages(self, node, args, kwargs):
        return self.add_languages(node, args, kwargs.get('required', True))

    @noKwargs
    def func_message(self, node, args, kwargs):
        # reduce arguments again to avoid flattening posargs
        (posargs, _) = self.reduce_arguments(node.args)
        if len(posargs) != 1:
            raise InvalidArguments('Expected 1 argument, got %d' % len(posargs))

        arg = posargs[0]
        if isinstance(arg, list):
            argstr = stringifyUserArguments(arg)
        elif isinstance(arg, str):
            argstr = arg
        elif isinstance(arg, int):
            argstr = str(arg)
        else:
            raise InvalidArguments('Function accepts only strings, integers, lists and lists thereof.')

        mlog.log(mlog.bold('Message:'), argstr)
        return


    @noKwargs
    def func_error(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        raise InterpreterException('Error encountered: ' + args[0])

    def detect_compilers(self, lang, need_cross_compiler):
        cross_comp = None
        if lang == 'c':
            comp = self.environment.detect_c_compiler(False)
            if need_cross_compiler:
                cross_comp = self.environment.detect_c_compiler(True)
        elif lang == 'cpp':
            comp = self.environment.detect_cpp_compiler(False)
            if need_cross_compiler:
                cross_comp = self.environment.detect_cpp_compiler(True)
        elif lang == 'objc':
            comp = self.environment.detect_objc_compiler(False)
            if need_cross_compiler:
                cross_comp = self.environment.detect_objc_compiler(True)
        elif lang == 'objcpp':
            comp = self.environment.detect_objcpp_compiler(False)
            if need_cross_compiler:
                cross_comp = self.environment.detect_objcpp_compiler(True)
        elif lang == 'java':
            comp = self.environment.detect_java_compiler()
            if need_cross_compiler:
                cross_comp = comp  # Java is platform independent.
        elif lang == 'cs':
            comp = self.environment.detect_cs_compiler()
            if need_cross_compiler:
                cross_comp = comp  # C# is platform independent.
        elif lang == 'vala':
            comp = self.environment.detect_vala_compiler()
            if need_cross_compiler:
                        cross_comp = comp  # Vala is too (I think).
        elif lang == 'rust':
            comp = self.environment.detect_rust_compiler()
            if need_cross_compiler:
                cross_comp = comp  # FIXME, probably not correct.
        elif lang == 'fortran':
            comp = self.environment.detect_fortran_compiler(False)
            if need_cross_compiler:
                cross_comp = self.environment.detect_fortran_compiler(True)
        elif lang == 'swift':
            comp = self.environment.detect_swift_compiler()
            if need_cross_compiler:
                raise InterpreterException('Cross compilation with Swift is not working yet.')
                # cross_comp = self.environment.detect_fortran_compiler(True)
        else:
            raise InvalidCode('Tried to use unknown language "%s".' % lang)
        comp.sanity_check(self.environment.get_scratch_dir())
        self.coredata.compilers[lang] = comp
        if cross_comp is not None:
            cross_comp.sanity_check(self.environment.get_scratch_dir())
            self.coredata.cross_compilers[lang] = cross_comp
        new_options = comp.get_options()
        optprefix = lang + '_'
        for i in new_options:
            if not i.startswith(optprefix):
                raise InterpreterException('Internal error, %s has incorrect prefix.' % i)
            cmd_prefix = i + '='
            for cmd_arg in self.environment.cmd_line_options.projectoptions:
                if cmd_arg.startswith(cmd_prefix):
                    value = cmd_arg.split('=', 1)[1]
                    new_options[i].set_value(value)
        new_options.update(self.coredata.compiler_options)
        self.coredata.compiler_options = new_options
        return (comp, cross_comp)

    def add_languages(self, node, args, required):
        success = True
        need_cross_compiler = self.environment.is_cross_build() and self.environment.cross_info.need_cross_compiler()
        for lang in args:
            lang = lang.lower()
            if lang in self.coredata.compilers:
                comp = self.coredata.compilers[lang]
                cross_comp = self.coredata.cross_compilers.get(lang, None)
            else:
                try:
                    (comp, cross_comp) = self.detect_compilers(lang, need_cross_compiler)
                except Exception:
                    if not required:
                        mlog.log('Compiler for language', mlog.bold(lang), 'not found.')
                        success = False
                        continue
                    else:
                        raise
            mlog.log('Native %s compiler: ' % lang, mlog.bold(' '.join(comp.get_exelist())), ' (%s %s)' % (comp.id, comp.version), sep='')
            if not comp.get_language() in self.coredata.external_args:
                (ext_compile_args, ext_link_args) = environment.get_args_from_envvars(comp.get_language())
                self.coredata.external_args[comp.get_language()] = ext_compile_args
                self.coredata.external_link_args[comp.get_language()] = ext_link_args
            self.build.add_compiler(comp)
            if need_cross_compiler:
                mlog.log('Cross %s compiler: ' % lang, mlog.bold(' '.join(cross_comp.get_exelist())), ' (%s %s)' % (cross_comp.id, cross_comp.version), sep='')
                self.build.add_cross_compiler(cross_comp)
            if self.environment.is_cross_build() and not need_cross_compiler:
                self.build.add_cross_compiler(comp)
            self.add_base_options(comp)
        return success

    def add_base_options(self, compiler):
        proj_opt = self.environment.cmd_line_options.projectoptions
        for optname in compiler.base_options:
            if optname in self.coredata.base_options:
                continue
            oobj = compilers.base_options[optname]
            for po in proj_opt:
                if po.startswith(optname + '='):
                    oobj.set_value(po.split('=', 1)[1])
                    break
            self.coredata.base_options[optname] = oobj

    def func_find_program(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        required = kwargs.get('required', True)
        if not isinstance(required, bool):
            raise InvalidArguments('"required" argument must be a boolean.')
        exename = args[0]
        # Search for scripts relative to current subdir.
        # Do not cache found programs because find_program('foobar')
        # might give different results when run from different source dirs.
        search_dir = os.path.join(self.environment.get_source_dir(), self.subdir)
        extprog = dependencies.ExternalProgram(exename, search_dir=search_dir)
        progobj = ExternalProgramHolder(extprog)
        if required and not progobj.found():
            raise InvalidArguments('Program "%s" not found.' % exename)
        return progobj

    def func_find_library(self, node, args, kwargs):
        mlog.log(mlog.red('DEPRECATION:'), 'find_library() is removed, use the corresponding method in compiler object instead.')

    def func_dependency(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        name = args[0]
        identifier = dependencies.get_dep_identifier(name, kwargs)
        if identifier in self.coredata.deps:
            dep = self.coredata.deps[identifier]
        else:
            dep = dependencies.Dependency() # Returns always false for dep.found()
        if not dep.found():
            try:
                dep = dependencies.find_external_dependency(name, self.environment, kwargs)
            except dependencies.DependencyException:
                if 'fallback' in kwargs:
                    return self.dependency_fallback(kwargs)
                raise
        self.coredata.deps[identifier] = dep
        return DependencyHolder(dep)

    def dependency_fallback(self, kwargs):
        fbinfo = kwargs['fallback']
        check_stringlist(fbinfo)
        if len(fbinfo) != 2:
            raise InterpreterException('Fallback info must have exactly two items.')
        dirname, varname = fbinfo
        self.do_subproject(dirname, kwargs)
        return self.subprojects[dirname].get_variable_method([varname], {})

    def func_executable(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, ExecutableHolder)

    def func_static_lib(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, StaticLibraryHolder)

    def func_shared_lib(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, SharedLibraryHolder)

    def func_library(self, node, args, kwargs):
        if self.coredata.get_builtin_option('default_library') == 'shared':
            return self.func_shared_lib(node, args, kwargs)
        return self.func_static_lib(node, args, kwargs)

    def func_jar(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, JarHolder)

    def func_build_target(self, node, args, kwargs):
        if 'target_type' not in kwargs:
            raise InterpreterException('Missing target_type keyword argument')
        target_type = kwargs.pop('target_type')
        if target_type == 'executable':
            return self.func_executable(node, args, kwargs)
        elif target_type == 'shared_library':
            return self.func_shared_lib(node, args, kwargs)
        elif target_type == 'static_library':
            return self.func_static_lib(node, args, kwargs)
        elif target_type == 'library':
            return self.func_library(node, args, kwargs)
        elif target_type == 'jar':
            return self.func_jar(node, args, kwargs)
        else:
            raise InterpreterException('Unknown target_type.')

    def func_vcs_tag(self, node, args, kwargs):
        fallback = kwargs.pop('fallback', None)
        if not isinstance(fallback, str):
            raise InterpreterException('Keyword argument fallback must exist and be a string.')
        replace_string = kwargs.pop('replace_string', '@VCS_TAG@')
        regex_selector = '(.*)' # default regex selector for custom command: use complete output
        vcs_cmd = kwargs.get('command', None)
        if vcs_cmd and not isinstance(vcs_cmd, list):
            vcs_cmd = [vcs_cmd]
        source_dir = os.path.normpath(os.path.join(self.environment.get_source_dir(), self.subdir))
        if vcs_cmd:
            # Is the command an executable in path or maybe a script in the source tree?
            vcs_cmd[0] = shutil.which(vcs_cmd[0]) or os.path.join(source_dir, vcs_cmd[0])
        else:
            vcs = mesonlib.detect_vcs(source_dir)
            if vcs:
                mlog.log('Found %s repository at %s' % (vcs['name'], vcs['wc_dir']))
                vcs_cmd = vcs['get_rev'].split()
                regex_selector = vcs['rev_regex']
            else:
                vcs_cmd = [' '] # executing this cmd will fail in vcstagger.py and force to use the fallback string
        # vcstagger.py parameters: infile, outfile, fallback, source_dir, replace_string, regex_selector, command...
        kwargs['command'] = [sys.executable,
                             self.environment.get_build_command(),
                             '--internal',
                             'vcstagger',
                             '@INPUT0@',
                             '@OUTPUT0@',
                             fallback,
                             source_dir,
                             replace_string,
                             regex_selector] + vcs_cmd
        kwargs.setdefault('build_always', True)
        return self.func_custom_target(node, [kwargs['output']], kwargs)

    @stringArgs
    def func_custom_target(self, node, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Incorrect number of arguments')
        name = args[0]
        tg = CustomTargetHolder(build.CustomTarget(name, self.subdir, kwargs))
        self.add_target(name, tg.held_object)
        return tg

    @noKwargs
    def func_run_target(self, node, args, kwargs):
        if len(args) < 2:
            raise InterpreterException('Incorrect number of arguments')
        cleaned_args = []
        for i in args:
            try:
                i = i.held_object
            except AttributeError:
                pass
            if not isinstance(i, (str, build.BuildTarget, build.CustomTarget)):
                mlog.debug('Wrong type:', str(i))
                raise InterpreterException('Invalid argument to run_target.')
            cleaned_args.append(i)
        name = cleaned_args[0]
        command = cleaned_args[1]
        cmd_args = cleaned_args[2:]
        tg = RunTargetHolder(name, command, cmd_args, self.subdir)
        self.add_target(name, tg.held_object)
        return tg

    def func_generator(self, node, args, kwargs):
        gen = GeneratorHolder(self, args, kwargs)
        self.generators.append(gen)
        return gen

    def func_benchmark(self, node, args, kwargs):
        self.add_test(node, args, kwargs, False)

    def func_test(self, node, args, kwargs):
        self.add_test(node, args, kwargs, True)

    def add_test(self, node, args, kwargs, is_base_test):
        if len(args) != 2:
            raise InterpreterException('Incorrect number of arguments')
        if not isinstance(args[0], str):
            raise InterpreterException('First argument of test must be a string.')
        if not isinstance(args[1], (ExecutableHolder, JarHolder, ExternalProgramHolder)):
            raise InterpreterException('Second argument must be executable.')
        par = kwargs.get('is_parallel', True)
        if not isinstance(par, bool):
            raise InterpreterException('Keyword argument is_parallel must be a boolean.')
        cmd_args = kwargs.get('args', [])
        if not isinstance(cmd_args, list):
            cmd_args = [cmd_args]
        for i in cmd_args:
            if not isinstance(i, (str, mesonlib.File)):
                raise InterpreterException('Command line arguments must be strings')
        envlist = kwargs.get('env', [])
        if not isinstance(envlist, list):
            envlist = [envlist]
        env = {}
        for e in envlist:
            if '=' not in e:
                raise InterpreterException('Env var definition must be of type key=val.')
            (k, val) = e.split('=', 1)
            k = k.strip()
            val = val.strip()
            if ' ' in k:
                raise InterpreterException('Env var key must not have spaces in it.')
            env[k] = val
        valgrind_args = kwargs.get('valgrind_args', [])
        if not isinstance(valgrind_args, list):
            valgrind_args = [valgrind_args]
        for a in valgrind_args:
            if not isinstance(a, str):
                raise InterpreterException('Valgrind_arg not a string.')
        should_fail = kwargs.get('should_fail', False)
        if not isinstance(should_fail, bool):
            raise InterpreterException('Keyword argument should_fail must be a boolean.')
        timeout = kwargs.get('timeout', 30)
        if 'workdir' in kwargs:
            workdir = kwargs['workdir']
            if not isinstance(workdir, str):
                raise InterpreterException('Workdir keyword argument must be a string.')
            if not os.path.isabs(workdir):
                raise InterpreterException('Workdir keyword argument must be an absolute path.')
        else:
            workdir = None
        if not isinstance(timeout, int):
            raise InterpreterException('Timeout must be an integer.')
        suite = mesonlib.stringlistify(kwargs.get('suite', ''))
        if self.is_subproject():
            newsuite = []
            for s in suite:
                if len(s) > 0:
                    s = '.' + s
                newsuite.append(self.subproject.replace(' ', '_').replace('.', '_') + s)
            suite = newsuite
        t = Test(args[0], suite, args[1].held_object, par, cmd_args, env, should_fail, valgrind_args, timeout, workdir)
        if is_base_test:
            self.build.tests.append(t)
            mlog.debug('Adding test "', mlog.bold(args[0]), '".', sep='')
        else:
            self.build.benchmarks.append(t)
            mlog.debug('Adding benchmark "', mlog.bold(args[0]), '".', sep='')

    @stringArgs
    def func_install_headers(self, node, args, kwargs):
        h = Headers(self.subdir, args, kwargs)
        self.build.headers.append(h)
        return h

    @stringArgs
    def func_install_man(self, node, args, kwargs):
        m = Man(self.subdir, args, kwargs)
        self.build.man.append(m)
        return m

    @noKwargs
    def func_subdir(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        if '..' in args[0]:
            raise InvalidArguments('Subdir contains ..')
        if self.subdir == '' and args[0] == self.subproject_dir:
            raise InvalidArguments('Must not go into subprojects dir with subdir(), use subproject() instead.')
        prev_subdir = self.subdir
        subdir = os.path.join(prev_subdir, args[0])
        if subdir in self.visited_subdirs:
            raise InvalidArguments('Tried to enter directory "%s", which has already been visited.'\
                                   % subdir)
        self.visited_subdirs[subdir] = True
        self.subdir = subdir
        try:
            os.makedirs(os.path.join(self.environment.build_dir, subdir))
        except FileExistsError:
            pass
        buildfilename = os.path.join(self.subdir, environment.build_filename)
        self.build_def_files.append(buildfilename)
        absname = os.path.join(self.environment.get_source_dir(), buildfilename)
        if not os.path.isfile(absname):
            self.subdir = prev_subdir
            raise InterpreterException('Nonexistant build def file %s.' % buildfilename)
        code = open(absname, encoding='utf8').read()
        assert(isinstance(code, str))
        try:
            codeblock = mparser.Parser(code).parse()
        except mesonlib.MesonException as me:
            me.file = buildfilename
            raise me
        self.evaluate_codeblock(codeblock)
        self.subdir = prev_subdir

    @stringArgs
    def func_install_data(self, node, args, kwargs):
        data = DataHolder(True, self.subdir, args, kwargs)
        self.build.data.append(data.held_object)
        return data

    @stringArgs
    def func_install_subdir(self, node, args, kwargs):
        if len(args) != 1:
            raise InvalidArguments('Install_subdir requires exactly one argument.')
        if not 'install_dir' in kwargs:
            raise InvalidArguments('Missing keyword argument install_dir')
        install_dir = kwargs['install_dir']
        if not isinstance(install_dir, str):
            raise InvalidArguments('Keyword argument install_dir not a string.')
        idir = InstallDir(self.subdir, args[0], install_dir)
        self.build.install_dirs.append(idir)
        return idir

    def func_configure_file(self, node, args, kwargs):
        if len(args) > 0:
            raise InterpreterException("configure_file takes only keyword arguments.")
        if not 'input' in kwargs:
            raise InterpreterException('Required keyword argument "input" not defined.')
        if not 'output' in kwargs:
            raise InterpreterException('Required keyword argument "output" not defined.')
        inputfile = kwargs['input']
        output = kwargs['output']
        if not isinstance(inputfile, str):
            raise InterpreterException('Input must be a string.')
        if not isinstance(output, str):
            raise InterpreterException('Output must be a string.')
        if os.path.split(output)[0] != '':
            raise InterpreterException('Output file name must not contain a subdirectory.')
        if 'configuration' in kwargs:
            conf = kwargs['configuration']
            if not isinstance(conf, ConfigurationDataHolder):
                raise InterpreterException('Argument "configuration" is not of type configuration_data')

            conffile = os.path.join(self.subdir, inputfile)
            if conffile not in self.build_def_files:
                self.build_def_files.append(conffile)
            os.makedirs(os.path.join(self.environment.build_dir, self.subdir), exist_ok=True)
            ifile_abs = os.path.join(self.environment.source_dir, self.subdir, inputfile)
            ofile_abs = os.path.join(self.environment.build_dir, self.subdir, output)
            mesonlib.do_conf_file(ifile_abs, ofile_abs, conf.held_object)
            conf.mark_used()
        elif 'command' in kwargs:
            res = self.func_run_command(node, kwargs['command'], {})
            if res.returncode != 0:
                raise InterpreterException('Running configure command failed.\n%s\n%s' %
                                           (res.stdout, res.stderr))
        else:
            raise InterpreterException('Configure_file must have either "configuration" or "command".')
        if isinstance(kwargs.get('install_dir', None), str):
            self.build.data.append(DataHolder(False, self.subdir, [output], kwargs).held_object)
        return mesonlib.File.from_built_file(self.subdir, output)

    @stringArgs
    def func_include_directories(self, node, args, kwargs):
        absbase = os.path.join(self.environment.get_source_dir(), self.subdir)
        for a in args:
            absdir = os.path.join(absbase, a)
            if not os.path.isdir(absdir):
                raise InvalidArguments('Include dir %s does not exist.' % a)
        is_system = kwargs.get('is_system', False)
        if not isinstance(is_system, bool):
            raise InvalidArguments('Is_system must be boolean.')
        i = IncludeDirsHolder(build.IncludeDirs(self.subdir, args, is_system))
        return i

    @stringArgs
    def func_add_global_arguments(self, node, args, kwargs):
        if self.subproject != '':
            raise InvalidCode('Global arguments can not be set in subprojects because there is no way to make that reliable.')
        if self.global_args_frozen:
            raise InvalidCode('Tried to set global arguments after a build target has been declared.\nThis is not permitted. Please declare all global arguments before your targets.')
        if not 'language' in kwargs:
            raise InvalidCode('Missing language definition in add_global_arguments')
        lang = kwargs['language'].lower()
        if lang in self.build.global_args:
            self.build.global_args[lang] += args
        else:
            self.build.global_args[lang] = args

    @stringArgs
    def func_add_global_link_arguments(self, node, args, kwargs):
        if self.subproject != '':
            raise InvalidCode('Global arguments can not be set in subprojects because there is no way to make that reliable.')
        if self.global_args_frozen:
            raise InvalidCode('Tried to set global arguments after a build target has been declared.\nThis is not permitted. Please declare all global arguments before your targets.')
        if not 'language' in kwargs:
            raise InvalidCode('Missing language definition in add_global_arguments')
        lang = kwargs['language'].lower()
        if lang in self.build.global_link_args:
            self.build.global_link_args[lang] += args
        else:
            self.build.global_link_args[lang] = args

    def flatten(self, args):
        if isinstance(args, mparser.StringNode):
            return args.value
        if isinstance(args, str):
            return args
        if isinstance(args, InterpreterObject):
            return args
        if isinstance(args, int):
            return args
        result = []
        for a in args:
            if isinstance(a, list):
                rest = self.flatten(a)
                result = result + rest
            elif isinstance(a, mparser.StringNode):
                result.append(a.value)
            else:
                result.append(a)
        return result

    def source_strings_to_files(self, sources):
        results = []
        for s in sources:
            if isinstance(s, mesonlib.File) or isinstance(s, GeneratedListHolder) or \
            isinstance(s, CustomTargetHolder):
                pass
            elif isinstance(s, str):
                s = mesonlib.File.from_source_file(self.environment.source_dir, self.subdir, s)
            else:
                raise InterpreterException("Source item is not string or File-type object.")
            results.append(s)
        return results

    def add_target(self, name, tobj):
        if name == '':
            raise InterpreterException('Target name must not be empty.')
        if name in coredata.forbidden_target_names:
            raise InvalidArguments('Target name "%s" is reserved for Meson\'s internal use. Please rename.'\
                                   % name)
        # To permit an executable and a shared library to have the
        # same name, such as "foo.exe" and "libfoo.a".
        idname = tobj.get_id()
        if idname in self.build.targets:
            raise InvalidCode('Tried to create target "%s", but a target of that name already exists.' % name)
        self.build.targets[idname] = tobj
        if idname not in self.coredata.target_guids:
            self.coredata.target_guids[idname] = str(uuid.uuid4()).upper()

    def build_target(self, node, args, kwargs, targetholder):
        name = args[0]
        sources = args[1:]
        if self.environment.is_cross_build():
            if kwargs.get('native', False):
                is_cross = False
            else:
                is_cross = True
        else:
            is_cross = False
        try:
            kw_src = self.flatten(kwargs['sources'])
            if not isinstance(kw_src, list):
                kw_src = [kw_src]
        except KeyError:
            kw_src = []
        sources += kw_src
        sources = self.source_strings_to_files(sources)
        objs = self.flatten(kwargs.get('objects', []))
        kwargs['dependencies'] = self.flatten(kwargs.get('dependencies', []))
        if not isinstance(objs, list):
            objs = [objs]
        self.check_sources_exist(os.path.join(self.source_root, self.subdir), sources)
        if targetholder is ExecutableHolder:
            targetclass = build.Executable
        elif targetholder is SharedLibraryHolder:
            targetclass = build.SharedLibrary
        elif targetholder is StaticLibraryHolder:
            targetclass = build.StaticLibrary
        elif targetholder is JarHolder:
            targetclass = build.Jar
        else:
            mlog.debug('Unknown target type:', str(targetholder))
            raise RuntimeError('Unreachable code')
        target = targetclass(name, self.subdir, self.subproject, is_cross, sources, objs, self.environment, kwargs)
        if is_cross:
            self.add_cross_stdlib_info(target)
        l = targetholder(target, self)
        self.add_target(name, l.held_object)
        self.global_args_frozen = True
        return l

    def get_used_languages(self, target):
        result = {}
        for i in target.sources:
            for c in self.build.compilers:
                if c.can_compile(i):
                    result[c.language] = True
                    break
        return result

    def add_cross_stdlib_info(self, target):
        for l in self.get_used_languages(target):
            if self.environment.cross_info.has_stdlib(l) and \
                self.subproject != self.environment.cross_info.get_stdlib(l)[0]:
                target.add_external_deps(self.build.cross_stdlibs[l])

    def check_sources_exist(self, subdir, sources):
        for s in sources:
            if not isinstance(s, str):
                continue # This means a generated source and they always exist.
            fname = os.path.join(subdir, s)
            if not os.path.isfile(fname):
                raise InterpreterException('Tried to add non-existing source %s.' % s)

    def function_call(self, node):
        func_name = node.func_name
        (posargs, kwargs) = self.reduce_arguments(node.args)
        if func_name in self.funcs:
            return self.funcs[func_name](node, self.flatten(posargs), kwargs)
        else:
            raise InvalidCode('Unknown function "%s".' % func_name)

    def is_assignable(self, value):
        if isinstance(value, InterpreterObject) or \
            isinstance(value, dependencies.Dependency) or\
            isinstance(value, str) or\
            isinstance(value, int) or \
            isinstance(value, list) or \
            isinstance(value, mesonlib.File):
            return True
        return False

    def assignment(self, node):
        assert(isinstance(node, mparser.AssignmentNode))
        var_name = node.var_name
        if not isinstance(var_name, str):
            raise InvalidArguments('Tried to assign value to a non-variable.')
        value = self.evaluate_statement(node.value)
        value = self.to_native(value)
        if not self.is_assignable(value):
            raise InvalidCode('Tried to assign an invalid value to variable.')
        self.set_variable(var_name, value)
        return value

    def reduce_arguments(self, args):
        assert(isinstance(args, mparser.ArgumentNode))
        if args.incorrect_order():
            raise InvalidArguments('All keyword arguments must be after positional arguments.')
        reduced_pos = [self.evaluate_statement(arg) for arg in args.arguments]
        reduced_kw = {}
        for key in args.kwargs.keys():
            if not isinstance(key, str):
                raise InvalidArguments('Keyword argument name is not a string.')
            a = args.kwargs[key]
            reduced_kw[key] = self.evaluate_statement(a)
        if not isinstance(reduced_pos, list):
            reduced_pos = [reduced_pos]
        return (reduced_pos, reduced_kw)

    def bool_method_call(self, obj, method_name, args):
        obj = self.to_native(obj)
        (posargs, _) = self.reduce_arguments(args)
        if method_name == 'to_string':
            if len(posargs) == 0:
                if obj == True:
                    return 'true'
                else:
                    return 'false'
            elif len(posargs) == 2 and isinstance(posargs[0], str) and isinstance(posargs[1], str):
                if obj == True:
                    return posargs[0]
                else:
                    return posargs[1]
            else:
                raise InterpreterException('bool.to_string() must have either no arguments or exactly two string arguments.')
        elif method_name == 'to_int':
            if obj == True:
                return 1
            else:
                return 0
        else:
            raise InterpreterException('Unknown method "%s" for a boolean.' % method_name)

    def string_method_call(self, obj, method_name, args):
        obj = self.to_native(obj)
        (posargs, _) = self.reduce_arguments(args)
        if method_name == 'strip':
            return obj.strip()
        elif method_name == 'format':
            return self.format_string(obj, args)
        elif method_name == 'to_upper':
            return obj.upper()
        elif method_name == 'to_lower':
            return obj.lower()
        elif method_name == 'underscorify':
            return re.sub(r'[^a-zA-Z0-9]', '_', obj)
        elif method_name == 'split':
            if len(posargs) > 1:
                raise InterpreterException('Split()  must have at most one argument.')
            elif len(posargs) == 1:
                s = posargs[0]
                if not isinstance(s, str):
                    raise InterpreterException('Split() argument must be a string')
                return obj.split(s)
            else:
                return obj.split()
        elif method_name == 'startswith' or method_name == 'contains' or method_name == 'endswith':
            s = posargs[0]
            if not isinstance(s, str):
                raise InterpreterException('Argument must be a string.')
            if method_name == 'startswith':
                return obj.startswith(s)
            elif method_name == 'contains':
                return obj.find(s) >= 0
            return obj.endswith(s)
        elif method_name == 'to_int':
            try:
                return int(obj)
            except Exception:
                raise InterpreterException('String can not be converted to int: ' + obj)
        elif method_name == 'join':
            if len(posargs) != 1:
                raise InterpreterException('Join() takes exactly one argument.')
            strlist = posargs[0]
            check_stringlist(strlist)
            return obj.join(strlist)
        elif method_name == 'version_compare':
            if len(posargs) != 1:
                raise InterpreterException('Version_compare() takes exactly one argument.')
            cmpr = posargs[0]
            if not isinstance(cmpr, str):
                raise InterpreterException('Version_compare() argument must be a string.')
            return mesonlib.version_compare(obj, cmpr)
        raise InterpreterException('Unknown method "%s" for a string.' % method_name)

    def to_native(self, arg):
        if isinstance(arg, mparser.StringNode) or \
           isinstance(arg, mparser.NumberNode) or \
           isinstance(arg, mparser.BooleanNode):
            return arg.value
        return arg

    def format_string(self, templ, args):
        templ = self.to_native(templ)
        if isinstance(args, mparser.ArgumentNode):
            args = args.arguments
        for (i, arg) in enumerate(args):
            arg = self.to_native(self.evaluate_statement(arg))
            if isinstance(arg, bool): # Python boolean is upper case.
                arg = str(arg).lower()
            templ = templ.replace('@{}@'.format(i), str(arg))
        return templ

    def method_call(self, node):
        invokable = node.source_object
        if isinstance(invokable, mparser.IdNode):
            object_name = invokable.value
            obj = self.get_variable(object_name)
        else:
            obj = self.evaluate_statement(invokable)
        method_name = node.name
        if method_name == 'extract_objects' and self.environment.coredata.get_builtin_option('unity'):
            raise InterpreterException('Single object files can not be extracted in Unity builds.')
        args = node.args
        if isinstance(obj, mparser.StringNode):
            obj = obj.get_value()
        if isinstance(obj, str):
            return self.string_method_call(obj, method_name, args)
        if isinstance(obj, bool):
            return self.bool_method_call(obj, method_name, args)
        if isinstance(obj, list):
            return self.array_method_call(obj, method_name, self.reduce_arguments(args)[0])
        if not isinstance(obj, InterpreterObject):
            raise InvalidArguments('Variable "%s" is not callable.' % object_name)
        (args, kwargs) = self.reduce_arguments(args)
        if method_name == 'extract_objects':
            self.validate_extraction(obj.held_object)
        return obj.method_call(method_name, self.flatten(args), kwargs)

    # Only permit object extraction from the same subproject
    def validate_extraction(self, buildtarget):
        if not self.subdir.startswith(self.subproject_dir):
            if buildtarget.subdir.startswith(self.subproject_dir):
                raise InterpreterException('Tried to extract objects from a subproject target.')
        else:
            if not buildtarget.subdir.startswith(self.subproject_dir):
                raise InterpreterException('Tried to extract objects from the main project from a subproject.')
            if self.subdir.split('/')[1] != buildtarget.subdir.split('/')[1]:
                raise InterpreterException('Tried to extract objects from a different subproject.')

    def array_method_call(self, obj, method_name, args):
        if method_name == 'contains':
            return self.check_contains(obj, args)
        elif method_name == 'length':
            return len(obj)
        elif method_name == 'get':
            index = args[0]
            if not isinstance(index, int):
                raise InvalidArguments('Array index must be a number.')
            if index < -len(obj) or index >= len(obj):
                raise InvalidArguments('Array index %s is out of bounds for array of size %d.' % (index, len(obj)))
            return obj[index]
        raise InterpreterException('Arrays do not have a method called "%s".' % method_name)

    def check_contains(self, obj, args):
        if len(args) != 1:
            raise InterpreterException('Contains method takes exactly one argument.')
        item = args[0]
        for element in obj:
            if isinstance(element, list):
                found = self.check_contains(element, args)
                if found:
                    return True
            try:
                if element == item:
                    return True
            except Exception:
                pass
        return False

    def evaluate_if(self, node):
        assert(isinstance(node, mparser.IfClauseNode))
        for i in node.ifs:
            result = self.evaluate_statement(i.condition)
            if not(isinstance(result, bool)):
                print(result)
                raise InvalidCode('If clause does not evaluate to true or false.')
            if result:
                self.evaluate_codeblock(i.block)
                return
        if not isinstance(node.elseblock, mparser.EmptyNode):
            self.evaluate_codeblock(node.elseblock)

    def evaluate_foreach(self, node):
        assert(isinstance(node, mparser.ForeachClauseNode))
        varname = node.varname.value
        items = self.evaluate_statement(node.items)
        if not isinstance(items, list):
            raise InvalidArguments('Items of foreach loop is not an array')
        for item in items:
            self.set_variable(varname, item)
            self.evaluate_codeblock(node.block)

    def evaluate_plusassign(self, node):
        assert(isinstance(node, mparser.PlusAssignmentNode))
        varname = node.var_name
        addition = self.evaluate_statement(node.value)
        # Remember that all variables are immutable. We must always create a
        # full new variable and then assign it.
        old_variable = self.get_variable(varname)
        if isinstance(old_variable, str):
          if not isinstance(addition, str):
            raise InvalidArguments('The += operator requires a string on the right hand side if the variable on the left is a string')
          new_value = old_variable + addition
        elif isinstance(old_variable, int):
          if not isinstance(addition, int):
            raise InvalidArguments('The += operator requires an int on the right hand side if the variable on the left is an int')
          new_value = old_variable + addition
        elif not isinstance(old_variable, list):
            raise InvalidArguments('The += operator currently only works with arrays, strings or ints ')
        # Add other data types here.
        else:
            if isinstance(addition, list):
                new_value = old_variable + addition
            else:
                new_value = old_variable + [addition]
        self.set_variable(varname, new_value)

    def evaluate_indexing(self, node):
        assert(isinstance(node, mparser.IndexNode))
        iobject = self.evaluate_statement(node.iobject)
        if not isinstance(iobject, list):
            raise InterpreterException('Tried to index a non-array object.')
        index = self.evaluate_statement(node.index)
        if not isinstance(index, int):
            raise InterpreterException('Index value is not an integer.')
        if index < -len(iobject) or index >= len(iobject):
            raise InterpreterException('Index %d out of bounds of array of size %d.' % (index, len(iobject)))
        return iobject[index]

    def is_elementary_type(self, v):
        if isinstance(v, (int, float, str, bool, list)):
            return True
        return False

    def evaluate_comparison(self, node):
        v1 = self.evaluate_statement(node.left)
        v2 = self.evaluate_statement(node.right)
        if self.is_elementary_type(v1):
            val1 = v1
        else:
            val1 = v1.value
        if self.is_elementary_type(v2):
            val2 = v2
        else:
            val2 = v2.value
        if node.ctype == '==':
            return val1 == val2
        elif node.ctype == '!=':
            return val1 != val2
        elif node.ctype == '<':
            return val1 < val2
        elif node.ctype == '<=':
            return val1 <= val2
        elif node.ctype == '>':
            return val1 > val2
        elif node.ctype == '>=':
            return val1 >= val2
        else:
            raise InvalidCode('You broke my compare eval.')

    def evaluate_andstatement(self, cur):
        l = self.evaluate_statement(cur.left)
        if isinstance(l, mparser.BooleanNode):
            l = l.value
        if not isinstance(l, bool):
            raise InterpreterException('First argument to "and" is not a boolean.')
        if not l:
            return False
        r = self.evaluate_statement(cur.right)
        if isinstance(r, mparser.BooleanNode):
            r = r.value
        if not isinstance(r, bool):
            raise InterpreterException('Second argument to "and" is not a boolean.')
        return r

    def evaluate_orstatement(self, cur):
        l = self.evaluate_statement(cur.left)
        if isinstance(l, mparser.BooleanNode):
            l = l.get_value()
        if not isinstance(l, bool):
            raise InterpreterException('First argument to "or" is not a boolean.')
        if l:
            return True
        r = self.evaluate_statement(cur.right)
        if isinstance(r, mparser.BooleanNode):
            r = r.get_value()
        if not isinstance(r, bool):
            raise InterpreterException('Second argument to "or" is not a boolean.')
        return r

    def evaluate_notstatement(self, cur):
        v = self.evaluate_statement(cur.value)
        if isinstance(v, mparser.BooleanNode):
            v = v.value
        if not isinstance(v, bool):
            raise InterpreterException('Argument to "not" is not a boolean.')
        return not v

    def evaluate_uminusstatement(self, cur):
        v = self.evaluate_statement(cur.value)
        if isinstance(v, mparser.NumberNode):
            v = v.value
        if not isinstance(v, int):
            raise InterpreterException('Argument to negation is not an integer.')
        return -v

    def evaluate_arithmeticstatement(self, cur):
        l = self.to_native(self.evaluate_statement(cur.left))
        r = self.to_native(self.evaluate_statement(cur.right))

        if cur.operation == 'add':
            try:
                return l + r
            except Exception as e:
                raise InvalidCode('Invalid use of addition: ' + str(e))
        elif cur.operation == 'sub':
            if not isinstance(l, int) or not isinstance(r, int):
                raise InvalidCode('Subtraction works only with integers.')
            return l - r
        elif cur.operation == 'mul':
            if not isinstance(l, int) or not isinstance(r, int):
                raise InvalidCode('Multiplication works only with integers.')
            return l * r
        elif cur.operation == 'div':
            if not isinstance(l, int) or not isinstance(r, int):
                raise InvalidCode('Division works only with integers.')
            return l // r
        else:
            raise InvalidCode('You broke me.')

    def evaluate_arraystatement(self, cur):
        (arguments, kwargs) = self.reduce_arguments(cur.args)
        if len(kwargs) > 0:
            raise InvalidCode('Keyword arguments are invalid in array construction.')
        return arguments

    def is_subproject(self):
        return self.subproject != ''