Add Java module

The Java module will serve as a source for easing Java development
within Meson. Currently it only supports generating native header files.

docs/markdown/Java-module.md

@@ -0,0 +1,15 @@
+# Java Module
+
+*Added 0.60.0*
+
+## Functions
+
+### `generate_native_header()`
+
+This function will generate a header file for use in Java native module
+development by reading the supplied Java file for `native` method declarations.
+
+Keyword arguments:
+
+- `package`: The [package](https://en.wikipedia.org/wiki/Java_package) of the
+file. If left empty, Meson will assume that there is no package.

docs/markdown/snippets/java_module.md

@@ -0,0 +1,18 @@
+## Java Module
+
+The Java module has been added to Meson. The Java module allows users to
+generate native header files without needing to use a `custom_target()`.
+
+```meson
+jmod = import('java')
+
+native_header = jmod.generate_native_header('File.java', package: 'com.mesonbuild')
+native_header_includes = include_directories('.')
+
+jdkjava = shared_module(
+  'jdkjava',
+  [native_header_includes, other_sources],
+  dependencies : [jdk],
+  include_directories : [native_header_includes]
+)
+```

docs/sitemap.txt

@@ -44,6 +44,7 @@ index.md
 			Gnome-module.md
 			Hotdoc-module.md
 			Icestorm-module.md
+			Java-module.md
 			Keyval-module.md
 			Pkgconfig-module.md
 			Python-3-module.md

docs/theme/extra/templates/navbar_links.html

@@ -15,6 +15,7 @@
             ("Hotdoc-module.html","Hotdoc"), \
             ("i18n-module.html","i18n"), \
             ("Icestorm-module.html","Icestorm"), \
+            ("Java-module.html","Java") \
             ("Keyval-module.html","Keyval"), \
             ("Pkgconfig-module.html","Pkgconfig"), \
             ("Python-3-module.html","Python 3"), \

mesonbuild/compilers/java.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 import os.path
 import shutil
 import subprocess
@@ -39,10 +40,10 @@ class JavaCompiler(BasicLinkerIsCompilerMixin, Compiler):
     def get_werror_args(self) -> T.List[str]:
         return ['-Werror']
 
-    def get_output_args(self, subdir: str) -> T.List[str]:
-        if subdir == '':
-            subdir = './'
-        return ['-d', subdir, '-s', subdir]
+    def get_output_args(self, outputname: str) -> T.List[str]:
+        if outputname == '':
+            outputname = './'
+        return ['-d', outputname, '-s', outputname]
 
     def get_pic_args(self) -> T.List[str]:
         return []

mesonbuild/modules/java.py

@@ -0,0 +1,76 @@
+# Copyright 2021 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.
+
+import os
+import pathlib
+import typing as T
+from mesonbuild.build import CustomTarget
+from mesonbuild.compilers import detect_compiler_for
+from mesonbuild.interpreterbase.decorators import FeatureNew, KwargInfo, typed_pos_args, typed_kwargs
+from mesonbuild.interpreter.interpreterobjects import FileHolder
+from mesonbuild.mesonlib import version_compare, MachineChoice
+from . import ExtensionModule, ModuleReturnValue, ModuleState
+from ..interpreter import Interpreter
+
+class JavaModule(ExtensionModule):
+    @FeatureNew('Java Module', '0.59.0')
+    def __init__(self, interpreter: Interpreter):
+        super().__init__(interpreter)
+        self.methods.update({
+            'generate_native_header': self.generate_native_header,
+        })
+
+        if 'java' not in interpreter.environment.coredata.compilers[MachineChoice.BUILD]:
+            detect_compiler_for(interpreter.environment, 'java', MachineChoice.BUILD)
+        self.javac = interpreter.environment.coredata.compilers[MachineChoice.BUILD]['java']
+
+    @typed_pos_args('generate_native_header', (str, FileHolder))
+    @typed_kwargs('java.generate_native_header', KwargInfo('package', str, default=None))
+    def generate_native_header(self, state: ModuleState, args: T.Tuple[T.Union[str, FileHolder]],
+            kwargs: T.Dict[str, T.Optional[str]]) -> ModuleReturnValue:
+        assert state.backend
+
+        package = kwargs.get('package')
+
+        file = self.interpreter.source_strings_to_files(
+            [a.held_object if isinstance(a, FileHolder) else a for a in args])[0]
+
+        if package:
+            header = f'{package.replace(".", "_")}_{pathlib.Path(file.fname).stem}.h'
+        else:
+            header = f'{pathlib.Path(file.fname).stem}.h'
+
+        ct_kwargs = {
+            'input': file,
+            'output': header,
+            'command': [
+                self.javac.exelist[0],
+                '-d',
+                '@PRIVATE_DIR@',
+                '-h',
+                state.subdir,
+                '@INPUT@',
+            ]
+        }
+
+        target = CustomTarget(os.path.basename(header), state.subdir, state.subproject, backend=state.backend, kwargs=ct_kwargs)
+        # It is only known that 1.8.0 won't pre-create the directory. 11 and 16
+        # do not exhibit this behavior.
+        if version_compare(self.javac.version, '1.8.0'):
+            pathlib.Path(state.backend.get_target_private_dir_abs(target)).mkdir(parents=True, exist_ok=True)
+
+        return ModuleReturnValue(target, [target])
+
+def initialize(*args: T.Any, **kwargs: T.Any) -> JavaModule:
+    return JavaModule(*args, **kwargs)

run_mypy.py

@@ -37,6 +37,7 @@ modules = [
     'mesonbuild/mintro.py',
     'mesonbuild/mlog.py',
     'mesonbuild/modules/fs.py',
+    'mesonbuild/modules/java.py',
     'mesonbuild/modules/unstable_rust.py',
     'mesonbuild/modules/qt.py',
     'mesonbuild/mparser.py',

test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.h

@@ -1,21 +0,0 @@
-/* DO NOT EDIT THIS FILE - it is machine generated */
-#include <jni.h>
-/* Header for class com_mesonbuild_JdkTest */
-
-#ifndef _Included_com_mesonbuild_JdkTest
-#define _Included_com_mesonbuild_JdkTest
-#ifdef __cplusplus
-extern "C" {
-#endif
-/*
- * Class:     com_mesonbuild_JdkTest
- * Method:    jdk_test
- * Signature: ()I
- */
-JNIEXPORT jint JNICALL Java_com_mesonbuild_JdkTest_jdk_1test
-  (JNIEnv *, jclass);
-
-#ifdef __cplusplus
-}
-#endif
-#endif

test cases/java/9 jdk/lib/meson.build

@@ -1,12 +1,16 @@
-sources = files(
+sources = [
+  files(
     'native.c',
     'com_mesonbuild_JdkTest.c',
-)
+  ),
+  native_header
+]
 
 jdkjava = shared_module(
   'jdkjava',
   sources,
   dependencies : [jdk],
+  include_directories : [native_header_includes]
 )
 
 jdkjava_dep = declare_dependency(

test cases/java/9 jdk/meson.build

@@ -9,10 +9,13 @@ if build_machine.system() == 'windows' and build_machine.cpu_family() == 'x86'
 endif
 
 fs = import('fs')
+javamod = import('java')
 
 java = find_program('java')
 
 jdk = dependency('jdk', version : '>=1.8')
 
+# generate native headers
+subdir('src/com/mesonbuild')
 subdir('lib')
 subdir('src')

test cases/java/9 jdk/src/com/mesonbuild/meson.build

@@ -0,0 +1,2 @@
+native_header = javamod.generate_native_header('JdkTest.java', package: 'com.mesonbuild')
+native_header_includes = include_directories('.')