meson/mesonbuild/build.py

# Copyright 2012-2014 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 coredata
from . import environment
from . import dependencies
from . import mlog
import copy, os
from .mesonlib import File, flatten

known_basic_kwargs = {'install' : True,
                      'c_pch' : True,
                      'cpp_pch' : True,
                      'c_args' : True,
                      'cpp_args' : True,
                      'cs_args' : True,
                      'vala_args' : True,
                      'link_args' : True,
                      'link_depends': True,
                      'link_with' : True,
                      'include_directories': True,
                      'dependencies' : True,
                      'install_dir' : True,
                      'main_class' : True,
                      'gui_app' : True,
                      'extra_files' : True,
                      'install_rpath' : True,
                      'resources' : True,
                      'sources' : True,
                      'objects' : True,
                      'native' : True,
                     }

known_shlib_kwargs = known_basic_kwargs.copy()
known_shlib_kwargs.update({'version' : True,
                           'soversion' : True})

backslash_explanation = \
'''Compiler arguments have a backslash "\\" character. This is unfortunately not
permitted. The reason for this is that backslash is a shell quoting character
that behaves differently across different systems. Because of this is it not
possible to make it work reliably across all the platforms Meson needs to
support.

There are several different ways of working around this issue. Most of the time
you are using this to provide a -D define to your compiler. Try instead to
create a config.h file and put all of your definitions in it using
configure_file().

Another approach is to move the backslashes into the source and have the other
bits in the def. So you would have an arg -DPLAIN_TEXT="foo" and then in your
C sources something like this:

const char *fulltext = "\\\\" PLAIN_TEXT;

We are fully aware that these are not really usable or pleasant ways to do
this but it's the best we can do given the way shell quoting works.
'''

class InvalidArguments(coredata.MesonException):
    pass

class Build:
    """A class that holds the status of one build including
    all dependencies and so on.
    """

    def __init__(self, environment):
        self.project_name = 'name of master project'
        self.project_version = None
        self.environment = environment
        self.projects = {}
        self.targets = {}
        self.compilers = []
        self.cross_compilers = []
        self.global_args = {}
        self.tests = []
        self.benchmarks = []
        self.headers = []
        self.man = []
        self.data = []
        self.static_linker = None
        self.static_cross_linker = None
        self.pot = []
        self.subprojects = {}
        self.install_scripts = []
        self.install_dirs = []
        self.dep_manifest_name = None
        self.dep_manifest = {}

    def has_language(self, language):
        for i in self.compilers:
            if i.get_language() == language:
                return True
        return False

    def add_compiler(self, compiler):
        if self.static_linker is None and compiler.needs_static_linker():
            self.static_linker = self.environment.detect_static_linker(compiler)
        if self.has_language(compiler.get_language()):
            return
        self.compilers.append(compiler)

    def add_cross_compiler(self, compiler):
        if len(self.cross_compilers) == 0:
            self.static_cross_linker = self.environment.detect_static_linker(compiler)
        for i in self.cross_compilers:
            if i.get_language() == compiler.get_language():
                return
        self.cross_compilers.append(compiler)

    def get_project(self):
        return self.projects['']

    def get_targets(self):
        return self.targets

    def get_tests(self):
        return self.tests

    def get_benchmarks(self):
        return self.benchmarks

    def get_headers(self):
        return self.headers

    def get_man(self):
        return self.man

    def get_data(self):
        return self.data

    def get_install_subdirs(self):
        return self.install_dirs

    def get_global_args(self, compiler):
        return self.global_args.get(compiler.get_language(), [])

class IncludeDirs():
    def __init__(self, curdir, dirs, is_system, extra_build_dirs=None):
        self.curdir = curdir
        self.incdirs = dirs
        self.is_system = is_system
        # Interpreter has validated that all given directories
        # actually exist.
        if extra_build_dirs is None:
            self.extra_build_dirs = []
        else:
            self.extra_build_dirs = extra_build_dirs

    def get_curdir(self):
        return self.curdir

    def get_incdirs(self):
        return self.incdirs

    def get_extra_build_dirs(self):
        return self.extra_build_dirs

class ExtractedObjects():
    def __init__(self, target, srclist):
        self.target = target
        self.srclist = srclist

class BuildTarget():
    def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
        self.name = name
        self.subdir = subdir
        self.subproject = subproject # Can not be calculated from subdir as subproject dirname can be changed per project.
        self.is_cross = is_cross
        self.sources = []
        self.objects = []
        self.external_deps = []
        self.include_dirs = []
        self.link_targets = []
        self.link_depends = []
        self.filename = 'no_name'
        self.need_install = False
        self.pch = {}
        self.extra_args = {}
        self.generated = []
        self.extra_files = []
        self.process_sourcelist(sources)
        self.process_objectlist(objects)
        self.process_kwargs(kwargs, environment)
        self.check_unknown_kwargs(kwargs)
        if len(self.sources) == 0 and \
            len(self.generated) == 0 and \
            len(self.objects) == 0:
            raise InvalidArguments('Build target %s has no sources.' % name)
        self.validate_sources()

    def get_id(self):
        # This ID must also be a valid file name on all OSs.
        # It should also avoid shell metacharacters for obvious
        # reasons.
        base = self.name + self.type_suffix()
        if self.subproject == '':
            return base
        return self.subproject + '@@' + base

    def check_unknown_kwargs(self, kwargs):
        # Override this method in derived classes that have more
        # keywords.
        self.check_unknown_kwargs_int(kwargs, known_basic_kwargs)

    def check_unknown_kwargs_int(self, kwargs, known_kwargs):
        unknowns = []
        for k in kwargs:
            if not k in known_kwargs:
                unknowns.append(k)
        if len(unknowns) > 0:
            mlog.log(mlog.bold('Warning:'), 'Unknown keyword argument(s) in target %s: %s.' %
                     (self.name, ', '.join(unknowns)))

    def process_objectlist(self, objects):
        assert(isinstance(objects, list))
        for s in objects:
            if hasattr(s, 'held_object'):
                s = s.held_object
            if isinstance(s, str):
                self.objects.append(s)
            elif isinstance(s, ExtractedObjects):
                self.objects.append(s)
            else:
                raise InvalidArguments('Bad object in target %s.' % self.name)

    def process_sourcelist(self, sources):
        if not isinstance(sources, list):
            sources = [sources]
        added_sources = {} # If the same source is defined multiple times, use it only once.
        for s in sources:
            # Holder unpacking. Ugly.
            if hasattr(s, 'held_object'):
                s = s.held_object
            if isinstance(s, File):
                if not s in added_sources:
                    self.sources.append(s)
                    added_sources[s] = True
            elif isinstance(s, GeneratedList) or isinstance(s, CustomTarget):
                self.generated.append(s)
            else:
                raise InvalidArguments('Bad source in target %s.' % self.name)

    def validate_sources(self):
        if len(self.sources) > 0:
            firstname = self.sources[0]
            if isinstance(firstname, File):
                firstname = firstname.fname
            first = os.path.split(firstname)[1]
            (base, suffix) = os.path.splitext(first)
            if suffix == '.rs':
                if self.name != base:
                    raise InvalidArguments('In Rust targets, the first source file must be named projectname.rs.')

    def get_original_kwargs(self):
        return self.kwargs

    def unpack_holder(self, d):
        if not isinstance(d, list):
            d = [d]
        newd = []
        for i in d:
            if hasattr(i, 'held_object'):
                newd.append(i.held_object)
            else:
                newd.append(i)
        return newd

    def copy_kwargs(self, kwargs):
        self.kwargs = copy.copy(kwargs)
        # This sucks quite badly. Arguments
        # are holders but they can't be pickled
        # so unpack those known.
        if 'dependencies' in self.kwargs:
            self.kwargs['dependencies'] = self.unpack_holder(self.kwargs['dependencies'])
        if 'link_with' in self.kwargs:
            self.kwargs['link_with'] = self.unpack_holder(self.kwargs['link_with'])

    def extract_objects(self, srcargs):
        obj_src = []
        for srclist in srcargs:
            if not isinstance(srclist, list):
                srclist = [srclist]
            for src in srclist:
                if not isinstance(src, str):
                    raise coredata.MesonException('Extraction arguments must be strings.')
                src = File(False, self.subdir, src)
                if src not in self.sources:
                    raise coredata.MesonException('Tried to extract unknown source %s.' % src)
                obj_src.append(src)
        return ExtractedObjects(self, obj_src)

    def extract_all_objects(self):
        return ExtractedObjects(self, self.sources)

    def get_all_link_deps(self):
        return self.get_transitive_link_deps()

    def get_transitive_link_deps(self):
        result = []
        for i in self.link_targets:
            result += i.get_all_link_deps()
        return result

    def get_custom_install_dir(self):
        return self.custom_install_dir

    def process_kwargs(self, kwargs, environment):
        self.copy_kwargs(kwargs)
        kwargs.get('modules', [])
        self.need_install = kwargs.get('install', self.need_install)
        llist = kwargs.get('link_with', [])
        if not isinstance(llist, list):
            llist = [llist]
        for linktarget in llist:
            # Sorry for this hack. Keyword targets are kept in holders
            # in kwargs. Unpack here without looking at the exact type.
            if hasattr(linktarget, "held_object"):
                linktarget = linktarget.held_object
            self.link(linktarget)
        c_pchlist = kwargs.get('c_pch', [])
        if not isinstance(c_pchlist, list):
            c_pchlist = [c_pchlist]
        self.add_pch('c', c_pchlist)
        cpp_pchlist = kwargs.get('cpp_pch', [])
        if not isinstance(cpp_pchlist, list):
            cpp_pchlist = [cpp_pchlist]
        self.add_pch('cpp', cpp_pchlist)
        clist = kwargs.get('c_args', [])
        if not isinstance(clist, list):
            clist = [clist]
        self.add_compiler_args('c', clist)
        cpplist = kwargs.get('cpp_args', [])
        if not isinstance(cpplist, list):
            cpplist = [cpplist]
        self.add_compiler_args('cpp', cpplist)
        cslist = kwargs.get('cs_args', [])
        if not isinstance(cslist, list):
            cslist = [cslist]
        self.add_compiler_args('cs', cslist)
        valalist = kwargs.get('vala_args', [])
        if not isinstance(valalist, list):
            valalist = [valalist]
        self.add_compiler_args('vala', valalist)
        self.link_args = kwargs.get('link_args', [])
        if not isinstance(self.link_args, list):
            self.link_args = [self.link_args]
        for i in self.link_args:
            if not isinstance(i, str):
                raise InvalidArguments('Link_args arguments must be strings.')
        self.link_depends = kwargs.get('link_depends', [])
        if not isinstance(self.link_depends, list):
            self.link_depends = [self.link_depends]
        for i in self.link_depends:
            if not isinstance(i, str):
                raise InvalidArguments('Link_depends arguments must be strings.')
        inclist = kwargs.get('include_directories', [])
        if not isinstance(inclist, list):
            inclist = [inclist]
        self.add_include_dirs(inclist)
        deplist = kwargs.get('dependencies', [])
        if not isinstance(deplist, list):
            deplist = [deplist]
        self.add_external_deps(deplist)
        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 InvalidArguments('Custom_install_dir must be a string')
        main_class = kwargs.get('main_class', '')
        if not isinstance(main_class, str):
            raise InvalidArguments('Main class must be a string')
        self.main_class = main_class
        if isinstance(self, Executable):
            self.gui_app = kwargs.get('gui_app', False)
            if not isinstance(self.gui_app, bool):
                raise InvalidArguments('Argument gui_app must be boolean.')
        elif 'gui_app' in kwargs:
            raise InvalidArguments('Argument gui_app can only be used on executables.')
        extra_files = kwargs.get('extra_files', [])
        if isinstance(extra_files, str):
            extra_files = [extra_files]
        for i in extra_files:
            if not isinstance(i, str):
                raise InvalidArguments('Arguments to extra_files must be strings.')
            trial = os.path.join(environment.get_source_dir(), self.subdir, i)
            if not(os.path.isfile(trial)):
                raise InvalidArguments('Tried to add non-existing extra file %s.' % i)
        self.extra_files = extra_files
        self.install_rpath = kwargs.get('install_rpath', '')
        if not isinstance(self.install_rpath, str):
            raise InvalidArguments('Install_rpath is not a string.')
        resources = kwargs.get('resources', [])
        if not isinstance(resources, list):
            resources = [resources]
        for r in resources:
            if not isinstance(r, str):
                raise InvalidArguments('Resource argument is not a string.')
            trial = os.path.join(environment.get_source_dir(), self.subdir, r)
            if not os.path.isfile(trial):
                raise InvalidArguments('Tried to add non-existing resource %s.' % r)
        self.resources = resources

    def get_subdir(self):
        return self.subdir

    def get_filename(self):
        return self.filename

    def get_extra_args(self, language):
        return self.extra_args.get(language, [])

    def get_dependencies(self):
        transitive_deps = []
        for t in self.link_targets:
            transitive_deps.append(t)
            if isinstance(t, StaticLibrary):
                transitive_deps += t.get_dependencies()
        return transitive_deps

    def get_basename(self):
        return self.name

    def get_source_subdir(self):
        return self.subdir

    def get_sources(self):
        return self.sources

    def get_objects(self):
        return self.objects

    def get_generated_sources(self):
        return self.generated

    def should_install(self):
        return self.need_install

    def has_pch(self):
        return len(self.pch) > 0

    def get_pch(self, language):
        try:
            return self.pch[language]
        except KeyError:
            return[]

    def get_include_dirs(self):
        return self.include_dirs

    def add_external_deps(self, deps):
        if not isinstance(deps, list):
            deps = [deps]
        for dep in deps:
            if hasattr(dep, 'held_object'):
                dep = dep.held_object
            if isinstance(dep, dependencies.InternalDependency):
                self.process_sourcelist(dep.sources)
                self.add_include_dirs(dep.include_directories)
                for l in dep.libraries:
                    self.link(l)
                self.add_external_deps(dep.ext_deps)
            elif isinstance(dep, dependencies.Dependency):
                self.external_deps.append(dep)
                self.process_sourcelist(dep.get_sources())
            else:
                raise InvalidArguments('Argument is not an external dependency')

    def get_external_deps(self):
        return self.external_deps

    def link(self, target):
        if not isinstance(target, list):
            target = [target]
        for t in target:
            if hasattr(t, 'held_object'):
                t = t.held_object
            if not isinstance(t, StaticLibrary) and \
            not isinstance(t, SharedLibrary):
                raise InvalidArguments('Link target is not library.')
            if self.is_cross != t.is_cross:
                raise InvalidArguments('Tried to mix cross built and native libraries in target %s.' % self.name)
            self.link_targets.append(t)

    def set_generated(self, genlist):
        for g in genlist:
            if not(isinstance(g, GeneratedList)):
                raise InvalidArguments('Generated source argument is not the output of a generator.')
            self.generated.append(g)

    def add_pch(self, language, pchlist):
        if len(pchlist) == 0:
            return
        elif len(pchlist) == 1:
            if not environment.is_header(pchlist[0]):
                raise InvalidArguments('Pch argument %s is not a header.' % pchlist[0])
        elif len(pchlist) == 2:
            if environment.is_header(pchlist[0]):
                if not environment.is_source(pchlist[1]):
                    raise InvalidArguments('PCH definition must contain one header and at most one source.')
            elif environment.is_source(pchlist[0]):
                if not environment.is_header(pchlist[1]):
                    raise InvalidArguments('PCH definition must contain one header and at most one source.')
                pchlist = [pchlist[1], pchlist[0]]
            else:
                raise InvalidArguments('PCH argument %s is of unknown type.' % pchlist[0])
        elif len(pchlist) > 2:
            raise InvalidArguments('PCH definition may have a maximum of 2 files.')
        self.pch[language] = pchlist

    def add_include_dirs(self, args):
        ids = []
        for a in args:
            # FIXME same hack, forcibly unpack from holder.
            if hasattr(a, 'held_object'):
                a = a.held_object
            if not isinstance(a, IncludeDirs):
                raise InvalidArguments('Include directory to be added is not an include directory object.')
            ids.append(a)
        self.include_dirs += ids

    def add_compiler_args(self, language, args):
        args = flatten(args)
        for a in args:
            if not isinstance(a, (str, File)):
                raise InvalidArguments('A non-string passed to compiler args.')
            if isinstance(a, str) and '\\' in a:
                raise InvalidArguments(backslash_explanation)
        if language in self.extra_args:
            self.extra_args[language] += args
        else:
            self.extra_args[language] = args

    def get_aliaslist(self):
        return []


class Generator():
    def __init__(self, args, kwargs):
        if len(args) != 1:
            raise InvalidArguments('Generator requires one and only one positional argument')
        
        exe = args[0]
        if hasattr(exe, 'held_object'):
            exe = exe.held_object
        if not isinstance(exe, Executable) and not isinstance(exe, dependencies.ExternalProgram):
            raise InvalidArguments('First generator argument must be an executable.')
        self.exe = exe
        self.process_kwargs(kwargs)

    def get_exe(self):
        return self.exe

    def process_kwargs(self, kwargs):
        if 'arguments' not in kwargs:
            raise InvalidArguments('Generator must have "arguments" keyword argument.')
        args = kwargs['arguments']
        if isinstance(args, str):
            args = [args]
        if not isinstance(args, list):
            raise InvalidArguments('"Arguments" keyword argument must be a string or a list of strings.')
        for a in args:
            if not isinstance(a, str):
                raise InvalidArguments('A non-string object in "arguments" keyword argument.')
        self.arglist = args

        if 'output' not in kwargs:
            raise InvalidArguments('Generator must have "output" keyword argument.')
        outputs = kwargs['output']
        if not isinstance(outputs, list):
            outputs = [outputs]
        for rule in outputs:
            if not isinstance(rule, str):
                raise InvalidArguments('"output" may only contain strings.')
            if not '@BASENAME@' in rule and not '@PLAINNAME@' in rule:
                raise InvalidArguments('Every element of "output" must contain @BASENAME@ or @PLAINNAME@.')
            if '/' in rule or '\\' in rule:
                raise InvalidArguments('"outputs" must not contain a directory separator.')
        if len(outputs) > 1:
            for o in outputs:
                if '@OUTPUT@' in o:
                    raise InvalidArguments('Tried to use @OUTPUT@ in a rule with more than one output.')
        self.outputs = outputs

    def get_base_outnames(self, inname):
        plainname = os.path.split(inname)[1]
        basename = plainname.split('.')[0]
        return [x.replace('@BASENAME@', basename).replace('@PLAINNAME@', plainname) for x in self.outputs]

    def get_arglist(self):
        return self.arglist

class GeneratedList():
    def __init__(self, generator, extra_args=[]):
        if hasattr(generator, 'held_object'):
            generator = generator.held_object
        self.generator = generator
        self.infilelist = []
        self.outfilelist = []
        self.outmap = {}
        self.extra_depends = []
        self.extra_args = extra_args

    def add_file(self, newfile):
        self.infilelist.append(newfile)
        outfiles = self.generator.get_base_outnames(newfile)
        self.outfilelist += outfiles
        self.outmap[newfile] = outfiles

    def get_infilelist(self):
        return self.infilelist

    def get_outfilelist(self):
        return self.outfilelist

    def get_outputs_for(self, filename):
        return self.outmap[filename]

    def get_generator(self):
        return self.generator

    def get_extra_args(self):
        return self.extra_args

class Executable(BuildTarget):
    def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
        super().__init__(name, subdir, subproject, is_cross, sources, objects, environment, kwargs)
        self.prefix = ''
        self.suffix = environment.get_exe_suffix()
        suffix = environment.get_exe_suffix()
        if len(self.sources) > 0 and self.sources[0].endswith('.cs'):
            suffix = 'exe'
        if suffix != '':
            self.filename = self.name + '.' + suffix
        else:
            self.filename = self.name

    def type_suffix(self):
        return "@exe"

class StaticLibrary(BuildTarget):
    def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
        super().__init__(name, subdir, subproject, is_cross, sources, objects, environment, kwargs)
        if len(self.sources) > 0 and self.sources[0].endswith('.cs'):
            raise InvalidArguments('Static libraries not supported for C#.')
        self.prefix = environment.get_static_lib_prefix()
        self.suffix = environment.get_static_lib_suffix()
        if len(self.sources) > 0 and self.sources[0].endswith('.rs'):
            self.suffix = 'rlib'
        self.filename = self.prefix + self.name + '.' + self.suffix

    def get_import_filename(self):
        return self.filename

    def get_osx_filename(self):
        return self.get_filename()

    def type_suffix(self):
        return "@sta"

class SharedLibrary(BuildTarget):
    def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
        self.version = None
        self.soversion = None
        super().__init__(name, subdir, subproject, is_cross, sources, objects, environment, kwargs);
        if len(self.sources) > 0 and self.sources[0].endswith('.cs'):
            self.suffix = 'dll'
            self.prefix = 'lib'
        else:
            self.prefix = environment.get_shared_lib_prefix()
            self.suffix = environment.get_shared_lib_suffix()
        if len(self.sources) > 0 and self.sources[0].endswith('.rs'):
            self.suffix = 'rlib'
        self.importsuffix = environment.get_import_lib_suffix()
        self.filename = self.prefix + self.name + '.' + self.suffix

    def process_kwargs(self, kwargs, environment):
        super().process_kwargs(kwargs, environment)
        if 'version' in kwargs:
            self.set_version(kwargs['version'])
        if 'soversion' in kwargs:
            self.set_soversion(kwargs['soversion'])

    def check_unknown_kwargs(self, kwargs):
        self.check_unknown_kwargs_int(kwargs, known_shlib_kwargs)

    def get_shbase(self):
        return self.prefix + self.name + '.' + self.suffix

    def get_import_filename(self):
        return self.prefix + self.name + '.' + self.importsuffix

    def get_all_link_deps(self):
        return [self] + self.get_transitive_link_deps()

    def get_filename(self):
        '''Works on all platforms except OSX, which does its own thing.'''
        fname = self.get_shbase()
        if self.version is None:
            return fname
        else:
            return fname + '.' + self.version

    def get_osx_filename(self):
        if self.version is None:
            return self.get_shbase()
        return self.prefix + self.name + '.' + self.version + '.' + self.suffix

    def set_version(self, version):
        if not isinstance(version, str):
            raise InvalidArguments('Shared library version is not a string.')
        self.version = version

    def set_soversion(self, version):
        if isinstance(version, int):
            version = str(version)
        if not isinstance(version, str):
            raise InvalidArguments('Shared library soversion is not a string or integer.')
        self.soversion = version

    def get_aliaslist(self):
        aliases = []
        if self.soversion is not None:
            aliases.append(self.get_shbase() + '.' + self.soversion)
        if self.version is not None:
            aliases.append(self.get_shbase())
        return aliases

    def type_suffix(self):
        return "@sha"

class CustomTarget:
    known_kwargs = {'input' : True,
                    'output' : True,
                    'command' : True,
                    'install' : True,
                    'install_dir' : True,
                    'build_always' : True,
                    'depends' : True,
                    'depend_files' : True,
                    }

    def __init__(self, name, subdir, kwargs):
        self.name = name
        self.subdir = subdir
        self.dependencies = []
        self.extra_depends = []
        self.depend_files = [] # Files that this target depends on but are not on the command line.
        self.process_kwargs(kwargs)
        self.extra_files = []
        self.install_rpath = ''
        unknowns = []
        for k in kwargs:
            if k not in CustomTarget.known_kwargs:
                unknowns.append(k)
        if len(unknowns) > 0:
            mlog.log(mlog.bold('Warning:'), 'Unknown keyword arguments in target %s: %s' %
                     (self.name, ', '.join(unknowns)))

    def get_id(self):
        return self.name + self.type_suffix()

    def process_kwargs(self, kwargs):
        self.sources = kwargs.get('input', [])
        if not isinstance(self.sources, list):
            self.sources = [self.sources]
        if 'output' not in kwargs:
            raise InvalidArguments('Missing keyword argument "output".')
        self.output = kwargs['output']
        if not isinstance(self.output, list):
            self.output = [self.output]
        for i in self.output:
            if not(isinstance(i, str)):
                raise InvalidArguments('Output argument not a string.')
            if '/' in i:
                raise InvalidArguments('Output must not contain a path segment.')
        if 'command' not in kwargs:
            raise InvalidArguments('Missing keyword argument "command".')
        cmd = kwargs['command']
        if not(isinstance(cmd, list)):
            cmd = [cmd]
        final_cmd = []
        for i, c in enumerate(cmd):
            if hasattr(c, 'held_object'):
                c = c.held_object
            if isinstance(c, str):
                final_cmd.append(c)
            elif isinstance(c, dependencies.ExternalProgram):
                final_cmd += c.get_command()
            elif isinstance(c, BuildTarget) or isinstance(c, CustomTarget):
                self.dependencies.append(c)
                final_cmd.append(c)
            elif isinstance(c, list):
                # Hackety hack, only supports one level of flattening. Should really
                # work to arbtrary depth.
                for s in c:
                    if not isinstance(s, str):
                        raise InvalidArguments('Array as argument %d contains a non-string.' % i)
                    final_cmd.append(s)
            else:
                raise InvalidArguments('Argument %s in "command" is invalid.' % i)
        self.command = final_cmd
        if 'install' in kwargs:
            self.install = kwargs['install']
            if not isinstance(self.install, bool):
                raise InvalidArguments('"install" must be boolean.')
            if 'install_dir' not in kwargs:
                raise InvalidArguments('"install_dir" not specified.')
            self.install_dir = kwargs['install_dir']
            if not(isinstance(self.install_dir, str)):
                raise InvalidArguments('"install_dir" must be a string.')
        else:
            self.install = False
        self.build_always = kwargs.get('build_always', False)
        if not isinstance(self.build_always, bool):
            raise InvalidArguments('Argument build_always must be a boolean.')
        extra_deps = kwargs.get('depends', [])
        if not isinstance(extra_deps, list):
            extra_deps = [extra_deps]
        for ed in extra_deps:
            while hasattr(ed, 'held_object'):
                ed = ed.held_object
            if not isinstance(ed, CustomTarget) and not isinstance(ed, BuildTarget):
                raise InvalidArguments('Can only depend on toplevel targets.')
            self.extra_depends.append(ed)
        depend_files = kwargs.get('depend_files', [])
        if not isinstance(depend_files, list):
            depend_files = [depend_files]
        for i in depend_files:
            if isinstance(i, (File, str)):
                self.depend_files.append(i)
            else:
                mlog.debug(i)
                raise InvalidArguments('Unknown type in depend_files.')

    def get_basename(self):
        return self.name

    def get_dependencies(self):
        return self.dependencies

    def should_install(self):
        return self.install

    def get_custom_install_dir(self):
        return self.install_dir

    def get_subdir(self):
        return self.subdir

    def get_filename(self):
        return self.output

    def get_aliaslist(self):
        return []

    def get_sources(self):
        return self.sources

    def get_generated_sources(self):
        return []

    def type_suffix(self):
        return "@cus"

class RunTarget:
    def __init__(self, name, command, args, subdir):
        self.name = name
        self.command = command
        self.args = args
        self.subdir = subdir

    def get_id(self):
        return self.name + self.type_suffix()

    def get_basename(self):
        return self.name

    def get_dependencies(self):
        return []

    def get_generated_sources(self):
        return []

    def get_sources(self):
        return []

    def get_subdir(self):
        return self.subdir

    def should_install(self):
        return False

    def get_filename(self):
        return self.name

    def type_suffix(self):
        return "@run"

class Jar(BuildTarget):
    def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
        super().__init__(name, subdir, subproject, is_cross, sources, objects, environment, kwargs);
        for s in self.sources:
            if not s.endswith('.java'):
                raise InvalidArguments('Jar source %s is not a java file.' % s)
        self.filename = self.name + '.jar'
        incdirs = kwargs.get('include_directories', [])

    def get_main_class(self):
        return self.main_class

    def type_suffix(self):
        return "@jar"

class ConfigureFile():

    def __init__(self, subdir, sourcename, targetname, configuration_data):
        self.subdir = subdir
        self.sourcename = sourcename
        self.targetname = targetname
        self.configuration_data = configuration_data

    def get_configuration_data(self):
        return self.configuration_data

    def get_subdir(self):
        return self.subdir

    def get_source_name(self):
        return self.sourcename

    def get_target_name(self):
        return self.targetname

class ConfigurationData():
    def __init__(self):
        super().__init__()
        self.values = {}

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

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

# A bit poorly named, but this represents plain data files to copy
# during install.
class Data():
    def __init__(self, in_sourcetree, source_subdir, sources, install_dir):
        self.in_sourcetree = in_sourcetree
        self.source_subdir = source_subdir
        self.sources = sources
        self.install_dir = install_dir

class InstallScript:
    def __init__(self, cmd_arr):
        assert(isinstance(cmd_arr, list))
        self.cmd_arr = cmd_arr