# 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 backends
from . import environment, mesonlib
from . import build
from . import mlog
from . import dependencies
from .mesonlib import File
from .backends import InstallData
from .build import InvalidArguments
from .coredata import MesonException
import os, sys, pickle, re
import subprocess, shutil

if mesonlib.is_windows():
    quote_char = '"'
    execute_wrapper = 'cmd /c'
else:
    quote_char = "'"
    execute_wrapper = ''

def ninja_quote(text):
    return text.replace(' ', '$ ').replace(':', '$:')

class RawFilename():
    def __init__(self, fname):
        self.fname = fname

    def split(self, c):
        return self.fname.split(c)

    def startswith(self, s):
        return self.fname.startswith(s)

class NinjaBuildElement():
    def __init__(self, outfilenames, rule, infilenames):
        if isinstance(outfilenames, str):
            self.outfilenames = [outfilenames]
        else:
            self.outfilenames = outfilenames
        assert(isinstance(rule, str))
        self.rule = rule
        if isinstance(infilenames, str):
            self.infilenames = [infilenames]
        else:
            self.infilenames = infilenames
        self.deps = []
        self.orderdeps = []
        self.elems = []

    def add_dep(self, dep):
        if isinstance(dep, list):
            self.deps += dep
        else:
            self.deps.append(dep)

    def add_orderdep(self, dep):
        if isinstance(dep, list):
            self.orderdeps += dep
        else:
            self.orderdeps.append(dep)

    def add_item(self, name, elems):
        if isinstance(elems, str):
            elems = [elems]
        self.elems.append((name, elems))

    def write(self, outfile):
        line = 'build %s: %s %s' % (' '.join([ninja_quote(i) for i in self.outfilenames]),\
                                    self.rule,
                                    ' '.join([ninja_quote(i) for i in self.infilenames]))
        if len(self.deps) > 0:
            line += ' | ' + ' '.join([ninja_quote(x) for x in self.deps])
        if len(self.orderdeps) > 0:
            line += ' || ' + ' '.join([ninja_quote(x) for x in self.orderdeps])
        line += '\n'
        # This is the only way I could find to make this work on all
        # platforms including Windows command shell. Slash is a dir separator
        # on Windows, too, so all characters are unambiguous and, more importantly,
        # do not require quoting.
        line = line.replace('\\', '/')
        outfile.write(line)

        for e in self.elems:
            (name, elems) = e
            should_quote = True
            if name == 'DEPFILE' or name == 'DESC' or name == 'pool':
                should_quote = False
            line = ' %s = ' % name
            q_templ = quote_char + "%s" + quote_char
            noq_templ = "%s"
            newelems = []
            for i in elems:
                if not should_quote or i == '&&': # Hackety hack hack
                    templ = noq_templ
                else:
                    templ = q_templ
                i = i.replace('\\', '\\\\')
                if quote_char == '"':
                    i = i.replace('"', '\\"')
                newelems.append(templ % ninja_quote(i))
            line += ' '.join(newelems)
            line += '\n'
            outfile.write(line)
        outfile.write('\n')

class NinjaBackend(backends.Backend):

    def __init__(self, build):
        super().__init__(build)
        self.source_suffix_in_objs = True
        self.ninja_filename = 'build.ninja'
        self.fortran_deps = {}
        self.all_outputs = {}

    def check_outputs(self, elem):
        for n in elem.outfilenames:
            if n in self.all_outputs:
                raise MesonException('Multiple producers for Ninja target "%s". Please rename your targets.' % n)
            self.all_outputs[n] = True

    def detect_vs_dep_prefix(self, outfile, tempfilename):
        '''VS writes its dependency in a locale dependent format.
        Detect the search prefix to use.'''
        if shutil.which('cl') is None:
            return outfile
        outfile.close()
        open(os.path.join(self.environment.get_scratch_dir(), 'incdetect.c'),
              'w').write('''#include<stdio.h>
int dummy;
''')

        pc = subprocess.Popen(['cl', '/showIncludes', '/c', 'incdetect.c'],
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE,
                              cwd=self.environment.get_scratch_dir())

        (stdo, _) = pc.communicate()

        for line in stdo.split(b'\r\n'):
            if line.endswith(b'stdio.h'):
                matchstr = b':'.join(line.split(b':')[0:2]) + b':'
                binfile = open(tempfilename, 'ab')
                binfile.write(b'msvc_deps_prefix = ' + matchstr + b'\r\n')
                binfile.close()
                return open(tempfilename, 'a')
        raise MesonException('Could not determine vs dep dependency prefix string.')

    def generate(self, interp):
        self.interpreter = interp
        outfilename = os.path.join(self.environment.get_build_dir(), self.ninja_filename)
        tempfilename = outfilename + '~'
        outfile = open(tempfilename, 'w')
        outfile.write('# This is the build file for project "%s"\n' % self.build.get_project())
        outfile.write('# It is autogenerated by the Meson build system.\n')
        outfile.write('# Do not edit by hand.\n\n')
        outfile.write('ninja_required_version = 1.5.1\n\n')
        outfile = self.detect_vs_dep_prefix(outfile, tempfilename)
        self.generate_rules(outfile)
        self.generate_phony(outfile)
        outfile.write('# Build rules for targets\n\n')
        [self.generate_target(t, outfile) for t in self.build.get_targets().values()]
        if len(self.build.pot) > 0:
            outfile.write('# Build rules for localisation.\n\n')
            self.generate_po(outfile)
        outfile.write('# Test rules\n\n')
        self.generate_tests(outfile)
        outfile.write('# Install rules\n\n')
        self.generate_install(outfile)
        if self.environment.coredata.get_builtin_option('coverage'):
            outfile.write('# Coverage rules\n\n')
            self.generate_coverage_rules(outfile)
        outfile.write('# Suffix\n\n')
        self.generate_ending(outfile)
        # Only ovewrite the old build file after the new one has been
        # fully created.
        outfile.close()
        os.replace(tempfilename, outfilename)
        self.generate_compdb()

    # http://clang.llvm.org/docs/JSONCompilationDatabase.html
    def generate_compdb(self):
        ninja_exe = environment.detect_ninja()
        builddir = self.environment.get_build_dir()
        jsondb = subprocess.check_output([ninja_exe, '-t', 'compdb', 'c_COMPILER', 'cpp_COMPILER'], cwd=builddir)
        open(os.path.join(builddir, 'compile_commands.json'), 'wb').write(jsondb)

    # Get all generated headers. Any source file might need them so
    # we need to add an order dependency to them.
    def get_generated_headers(self, target):
        header_deps = []
        for gensource in target.get_generated_sources():
            if isinstance(gensource, build.CustomTarget):
                continue
            for src in gensource.get_outfilelist():
                if self.environment.is_header(src):
                    header_deps.append(os.path.join(self.get_target_private_dir(target), src))
        for dep in target.link_targets:
            if isinstance(dep, (build.StaticLibrary, build.SharedLibrary)):
                header_deps += self.get_generated_headers(dep)
        return header_deps

    def generate_target(self, target, outfile):
        if isinstance(target, build.CustomTarget):
            self.generate_custom_target(target, outfile)
        if isinstance(target, build.RunTarget):
            self.generate_run_target(target, outfile)
        name = target.get_id()
        gen_src_deps = []
        if name in self.processed_targets:
            return
        if isinstance(target, build.Jar):
            self.generate_jar_target(target, outfile)
            return
        if 'rust' in self.environment.coredata.compilers.keys() and self.has_rust(target):
            self.generate_rust_target(target, outfile)
            return
        if 'cs' in self.environment.coredata.compilers.keys() and self.has_cs(target):
            self.generate_cs_target(target, outfile)
            return
        if 'vala' in self.environment.coredata.compilers.keys() and self.has_vala(target):
            gen_src_deps += self.generate_vala_compile(target, outfile)
        if 'swift' in self.environment.coredata.compilers.keys() and self.has_swift(target):
            self.generate_swift_target(target, outfile)
            return
        self.scan_fortran_module_outputs(target)
        # The following deals with C/C++ compilation.
        (gen_src, gen_other_deps) = self.process_dep_gens(outfile, target)
        gen_src_deps += gen_src
        self.process_target_dependencies(target, outfile)
        self.generate_custom_generator_rules(target, outfile)
        outname = self.get_target_filename(target)
        obj_list = []
        use_pch = self.environment.coredata.get_builtin_option('use_pch')
        is_unity = self.environment.coredata.get_builtin_option('unity')
        if use_pch and target.has_pch():
            pch_objects = self.generate_pch(target, outfile)
        else:
            pch_objects = []
        header_deps = gen_other_deps
        unity_src = []
        unity_deps = [] # Generated sources that must be built before compiling a Unity target.
        header_deps += self.get_generated_headers(target)
        for gensource in target.get_generated_sources():
            if isinstance(gensource, build.CustomTarget):
                for src in gensource.output:
                    src = os.path.join(self.get_target_dir(gensource), src)
                    if self.environment.is_source(src) and not self.environment.is_header(src):
                        if is_unity:
                            unity_deps.append(os.path.join(self.environment.get_build_dir(), RawFilename(src)))
                        else:
                            obj_list.append(self.generate_single_compile(target, outfile, RawFilename(src), True,
                                                                         header_deps))
                    elif self.environment.is_object(src):
                        obj_list.append(src)
                    elif self.environment.is_library(src):
                        pass
                    else:
                        # Assume anything not specifically a source file is a header. This is because
                        # people generate files with weird suffixes (.inc, .fh) that they then include
                        # in their source files.
                        header_deps.append(RawFilename(src))
            else:
                for src in gensource.get_outfilelist():
                    if self.environment.is_object(src):
                        obj_list.append(os.path.join(self.get_target_private_dir(target), src))
                    elif not self.environment.is_header(src):
                        if is_unity:
                            if self.has_dir_part(src):
                                rel_src = src
                            else:
                                rel_src = os.path.join(self.get_target_private_dir(target), src)
                            unity_deps.append(rel_src)
                            abs_src = os.path.join(self.environment.get_build_dir(), rel_src)
                            unity_src.append(abs_src)
                        else:
                            obj_list.append(self.generate_single_compile(target, outfile, src, True,
                                                                         header_deps=header_deps))
        src_list = []
        for src in gen_src_deps:
                src_list.append(src)
                if is_unity:
                    unity_src.append(os.path.join(self.environment.get_build_dir(), src))
                    header_deps.append(src)
                else:
                    # Generated targets are ordered deps because the must exist
                    # before the sources compiling them are used. After the first
                    # compile we get precise dependency info from dep files.
                    # This should work in all cases. If it does not, then just
                    # move them from orderdeps to proper deps.
                    obj_list.append(self.generate_single_compile(target, outfile, src, True, [], header_deps))
        for src in target.get_sources():
            if src.endswith('.vala'):
                continue
            if not self.environment.is_header(src):
                src_list.append(src)
                if is_unity:
                    abs_src = os.path.join(self.environment.get_build_dir(),
                                           src.rel_to_builddir(self.build_to_src))
                    unity_src.append(abs_src)
                else:
                    obj_list.append(self.generate_single_compile(target, outfile, src, False, [], header_deps))
        obj_list += self.flatten_object_list(target)
        if is_unity:
            for src in self.generate_unity_files(target, unity_src):
                obj_list.append(self.generate_single_compile(target, outfile, src, True, unity_deps + header_deps))
        linker = self.determine_linker(target, src_list)
        elem = self.generate_link(target, outfile, outname, obj_list, linker, pch_objects)
        self.generate_shlib_aliases(target, self.get_target_dir(target))
        elem.write(outfile)
        self.processed_targets[name] = True

    def process_target_dependencies(self, target, outfile):
        for t in target.get_dependencies():
            tname = t.get_basename() + t.type_suffix()
            if not tname in self.processed_targets:
                self.generate_target(t, outfile)

    def generate_custom_target(self, target, outfile):
        (srcs, ofilenames, cmd) = self.eval_custom_target_command(target)
        deps = []
        for i in target.get_dependencies():
            # FIXME, should not grab element at zero but rather expand all.
            if isinstance(i, list):
                i = i[0]
            fname = i.get_filename()
            if isinstance(fname, list):
                fname = fname[0]
            deps.append(os.path.join(self.get_target_dir(i), fname))
        if target.build_always:
            deps.append('PHONY')
        elem = NinjaBuildElement(ofilenames, 'CUSTOM_COMMAND', srcs)
        for i in target.depend_files:
            if isinstance(i, mesonlib.File):
                deps.append(i.rel_to_builddir(self.build_to_src))
            else:
                deps.append(os.path.join(self.build_to_src, i))
        elem.add_dep(deps)
        for d in target.extra_depends:
            tmp = d.get_filename()
            if not isinstance(tmp, list):
                tmp = [tmp]
            for fname in tmp:
                elem.add_dep(os.path.join(self.get_target_dir(d), fname))

        elem.add_item('COMMAND', cmd)
        elem.add_item('description', 'Generating %s with a custom command.' % target.name)
        elem.write(outfile)
        self.check_outputs(elem)
        self.processed_targets[target.name + target.type_suffix()] = True

    def generate_run_target(self, target, outfile):
        runnerscript = os.path.join(self.environment.get_script_dir(), 'commandrunner.py')
        deps = []
        arg_strings = []
        for i in target.args:
            if isinstance(i, str):
                arg_strings.append(i)
            elif isinstance(i, (build.BuildTarget, build.CustomTarget)):
                relfname = self.get_target_filename(i)
                deps.append(relfname)
                arg_strings.append(os.path.join(self.environment.get_build_dir(), relfname))
            else:
                mlog.debug(str(i))
                raise MesonException('Unreachable code in generate_run_target.')
        elem = NinjaBuildElement(target.name, 'CUSTOM_COMMAND', deps)
        cmd = [sys.executable, runnerscript, self.environment.get_source_dir(), self.environment.get_build_dir(), target.subdir]
        texe = target.command
        try:
            texe = texe.held_object
        except AttributeError:
            pass
        if isinstance(texe, build.Executable):
            abs_exe = os.path.join(self.environment.get_build_dir(), self.get_target_filename(texe))
            deps.append(self.get_target_filename(texe))
            if self.environment.is_cross_build() \
                and self.environment.cross_info.config['binaries'].get('exe_wrapper', None) is not None:
                cmd += [self.environment.cross_info.config['binaries']['exe_wrapper']]
            cmd.append(abs_exe)
        else:
            cmd.append(target.command)
        cmd += arg_strings
        elem.add_item('COMMAND', cmd)
        elem.add_item('description', 'Running external command %s.' % target.name)
        elem.add_item('pool', 'console')
        elem.write(outfile)
        self.check_outputs(elem)
        self.processed_targets[target.name + target.type_suffix()] = True

    def generate_po(self, outfile):
        for p in self.build.pot:
            (packagename, languages, subdir) = p
            input_file = os.path.join(subdir, 'POTFILES')
            elem = NinjaBuildElement('pot', 'GEN_POT', [])
            elem.add_item('PACKAGENAME', packagename)
            elem.add_item('OUTFILE', packagename + '.pot')
            elem.add_item('FILELIST', os.path.join(self.environment.get_source_dir(), input_file))
            elem.add_item('OUTDIR', os.path.join(self.environment.get_source_dir(), subdir))
            elem.write(outfile)
            self.check_outputs(elem)
            for l in languages:
                infile = os.path.join(self.environment.get_source_dir(), subdir, l + '.po')
                outfilename = os.path.join(subdir, l + '.gmo')
                lelem = NinjaBuildElement(outfilename, 'GEN_GMO', infile)
                lelem.add_item('INFILE', infile)
                lelem.add_item('OUTFILE', outfilename)
                lelem.write(outfile)
                self.check_outputs(lelem)

    def generate_coverage_rules(self, outfile):
        (gcovr_exe, lcov_exe, genhtml_exe) = environment.find_coverage_tools()
        added_rule = False
        if gcovr_exe:
            added_rule = True
            elem = NinjaBuildElement('coverage-xml', 'CUSTOM_COMMAND', '')
            elem.add_item('COMMAND', [gcovr_exe, '-x', '-r', self.environment.get_build_dir(),\
                                      '-o', os.path.join(self.environment.get_log_dir(), 'coverage.xml')])
            elem.add_item('DESC', 'Generating XML coverage report.')
            elem.write(outfile)
            elem = NinjaBuildElement('coverage-text', 'CUSTOM_COMMAND', '')
            elem.add_item('COMMAND', [gcovr_exe, '-r', self.environment.get_build_dir(),\
                                      '-o', os.path.join(self.environment.get_log_dir(), 'coverage.txt')])
            elem.add_item('DESC', 'Generating text coverage report.')
            elem.write(outfile)
            self.check_outputs(elem)
        if lcov_exe and genhtml_exe:
            added_rule = True
            phony_elem = NinjaBuildElement('coverage-html', 'phony', 'coveragereport/index.html')
            phony_elem.write(outfile)

            elem = NinjaBuildElement('coveragereport/index.html', 'CUSTOM_COMMAND', '')
            command = [lcov_exe, '--directory', self.environment.get_build_dir(),\
                       '--capture', '--output-file', 'coverage.info', '--no-checksum',\
                       '&&', genhtml_exe, '--prefix', self.environment.get_build_dir(),\
                       '--output-directory', self.environment.get_log_dir(), '--title', 'Code coverage',\
                       '--legend', '--show-details', 'coverage.info']
            elem.add_item('COMMAND', command)
            elem.add_item('DESC', 'Generating HTML coverage report.')
            self.check_outputs(elem)
            elem.write(outfile)
        if not added_rule:
            mlog.log(mlog.red('Warning:'), 'coverage requested but neither gcovr nor lcov/genhtml found.')

    def generate_install(self, outfile):
        script_root = self.environment.get_script_dir()
        install_script = os.path.join(script_root, 'meson_install.py')
        install_data_file = os.path.join(self.environment.get_scratch_dir(), 'install.dat')
        depfixer = os.path.join(script_root, 'depfixer.py')
        d = InstallData(self.environment.get_source_dir(),
                        self.environment.get_build_dir(),
                        self.environment.get_prefix(), depfixer)
        elem = NinjaBuildElement('install', 'CUSTOM_COMMAND', 'PHONY')
        elem.add_dep('all')
        elem.add_item('DESC', 'Installing files.')
        elem.add_item('COMMAND', [sys.executable, install_script, install_data_file])
        elem.add_item('pool', 'console')
        self.generate_depmf_install(d)
        self.generate_target_install(d)
        self.generate_header_install(d)
        self.generate_man_install(d)
        self.generate_data_install(d)
        self.generate_po_install(d, elem)
        self.generate_custom_install_script(d)
        self.generate_subdir_install(d)
        elem.write(outfile)
        self.check_outputs(elem)

        ofile = open(install_data_file, 'wb')
        pickle.dump(d, ofile)

    def generate_po_install(self, d, elem):
        for p in self.build.pot:
            (package_name, languages, subdir) = p
            # FIXME: assumes only one po package per source
            d.po_package_name = package_name
            for lang in languages:
                rel_src =  os.path.join(subdir, lang + '.gmo')
                src_file = os.path.join(self.environment.get_build_dir(), rel_src)
                d.po.append((src_file, self.environment.coredata.get_builtin_option('localedir'), lang))
                elem.add_dep(rel_src)

    def generate_target_install(self, d):
        libdir = self.environment.get_libdir()
        bindir = self.environment.get_bindir()

        should_strip = self.environment.coredata.get_builtin_option('strip')
        for t in self.build.get_targets().values():
            if t.should_install():
                outdir = t.get_custom_install_dir()
                if outdir is None:
                    if isinstance(t, build.Executable):
                        outdir = bindir
                    else:
                        outdir = libdir
                i = [self.get_target_filename(t), outdir, t.get_aliaslist(),\
                    should_strip, t.install_rpath]
                d.targets.append(i)

    def generate_custom_install_script(self, d):
        d.install_scripts = self.build.install_scripts

    def generate_header_install(self, d):
        incroot = self.environment.get_includedir()
        headers = self.build.get_headers()

        for h in headers:
            outdir = h.get_custom_install_dir()
            if outdir is None:
                outdir = os.path.join(incroot, h.get_install_subdir())
            for f in h.get_sources():
                abspath = os.path.join(self.environment.get_source_dir(), h.get_source_subdir(), f)
                i = [abspath, outdir]
                d.headers.append(i)

    def generate_man_install(self, d):
        manroot = self.environment.get_mandir()
        man = self.build.get_man()
        for m in man:
            for f in m.get_sources():
                num = f.split('.')[-1]
                subdir = m.get_custom_install_dir()
                if subdir is None:
                    subdir = os.path.join(manroot, 'man' + num)
                srcabs = os.path.join(self.environment.get_source_dir(), m.get_source_subdir(), f)
                dstabs = os.path.join(subdir, f + '.gz')
                i = [srcabs, dstabs]
                d.man.append(i)

    def generate_data_install(self, d):
        data = self.build.get_data()
        for de in data:
            assert(isinstance(de, build.Data))
            subdir = de.install_dir
            for f in de.sources:
                if de.in_sourcetree:
                    srcprefix = self.environment.get_source_dir()
                else:
                    srcprefix = self.environment.get_build_dir()
                srcabs = os.path.join(srcprefix, de.source_subdir, f)
                dstabs = os.path.join(subdir, f)
                i = [srcabs, dstabs]
                d.data.append(i)

    def generate_subdir_install(self, d):
        for sd in self.build.get_install_subdirs():
            src_dir = os.path.join(self.environment.get_source_dir(), sd.source_subdir, sd.installable_subdir)
            dst_dir = os.path.join(self.environment.get_prefix(), sd.install_dir)
            d.install_subdirs.append([src_dir, dst_dir])

    def write_test_suite_targets(self, cmd, outfile):
        suites = {}
        for t in self.build.get_tests():
            for s in t.suite:
                suites[s] = True
        suites = list(suites.keys())
        suites.sort()
        for s in suites:
            if s == '':
                visible_name = 'for top level tests'
            else:
                visible_name = s
            elem = NinjaBuildElement('test-' + s, 'CUSTOM_COMMAND', ['all', 'PHONY'])
            elem.add_item('COMMAND', cmd + ['--suite=' + s])
            elem.add_item('DESC', 'Running test suite %s.' % visible_name)
            elem.add_item('pool', 'console')
            elem.write(outfile)
            self.check_outputs(elem)

    def generate_tests(self, outfile):
        self.serialise_tests()
        valgrind = environment.find_valgrind()
        script_root = self.environment.get_script_dir()
        test_data = os.path.join(self.environment.get_scratch_dir(), 'meson_test_setup.dat')
        cmd = [sys.executable, self.environment.get_build_command(), '--internal', 'test', test_data]
        elem = NinjaBuildElement('test', 'CUSTOM_COMMAND', ['all', 'PHONY'])
        elem.add_item('COMMAND', cmd)
        elem.add_item('DESC', 'Running all tests.')
        elem.add_item('pool', 'console')
        elem.write(outfile)
        self.check_outputs(elem)
        self.write_test_suite_targets(cmd, outfile)

        if valgrind:
            velem = NinjaBuildElement('test-valgrind', 'CUSTOM_COMMAND', ['all', 'PHONY'])
            velem.add_item('COMMAND', cmd + ['--wrapper=' + valgrind])
            velem.add_item('DESC', 'Running test suite under Valgrind.')
            velem.add_item('pool', 'console')
            velem.write(outfile)
            self.check_outputs(velem)

        # And then benchmarks.
        benchmark_script = os.path.join(script_root, 'meson_benchmark.py')
        benchmark_data = os.path.join(self.environment.get_scratch_dir(), 'meson_benchmark_setup.dat')
        cmd = [sys.executable, self.environment.get_build_command(), '--internal', 'benchmark', benchmark_data]
        elem = NinjaBuildElement('benchmark', 'CUSTOM_COMMAND', ['all', 'PHONY'])
        elem.add_item('COMMAND', cmd)
        elem.add_item('DESC', 'Running benchmark suite.')
        elem.add_item('pool', 'console')
        elem.write(outfile)
        self.check_outputs(elem)

    def generate_rules(self, outfile):
        outfile.write('# Rules for compiling.\n\n')
        self.generate_compile_rules(outfile)
        outfile.write('# Rules for linking.\n\n')
        if self.environment.is_cross_build():
            self.generate_static_link_rules(True, outfile)
        self.generate_static_link_rules(False, outfile)
        self.generate_dynamic_link_rules(outfile)
        outfile.write('# Other rules\n\n')
        outfile.write('rule CUSTOM_COMMAND\n')
        outfile.write(' command = $COMMAND\n')
        outfile.write(' description = $DESC\n')
        outfile.write(' restat = 1\n\n')
        outfile.write('rule REGENERATE_BUILD\n')
        c = (quote_char + ninja_quote(sys.executable) + quote_char,
             quote_char + ninja_quote(self.environment.get_build_command())  + quote_char,
             '--internal',
             'regenerate',
             quote_char + ninja_quote(self.environment.get_source_dir())  + quote_char,
             quote_char + ninja_quote(self.environment.get_build_dir())  + quote_char)
        outfile.write(" command = %s %s %s %s %s %s --backend ninja\n" % c)
        outfile.write(' description = Regenerating build files\n')
        outfile.write(' generator = 1\n\n')
        if len(self.build.pot) > 0:
            self.generate_gettext_rules(outfile)
        outfile.write('\n')

    def generate_gettext_rules(self, outfile):
        rule = 'rule GEN_POT\n'
        command = " command = xgettext --package-name=$PACKAGENAME -p $OUTDIR -f $FILELIST -D '%s' -k_ -o $OUTFILE\n" % \
        self.environment.get_source_dir()
        desc = " description = Creating pot file for package $PACKAGENAME.\n"
        outfile.write(rule)
        outfile.write(command)
        outfile.write(desc)
        outfile.write('\n')
        rule = 'rule GEN_GMO\n'
        command = ' command = msgfmt $INFILE -o $OUTFILE\n'
        desc = ' description = Generating gmo file $OUTFILE\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(desc)
        outfile.write('\n')

    def generate_phony(self, outfile):
        outfile.write('# Phony build target, always out of date\n')
        outfile.write('build PHONY: phony\n')
        outfile.write('\n')

    def generate_jar_target(self, target, outfile):
        fname = target.get_filename()
        subdir = target.get_subdir()
        outname_rel = os.path.join(self.get_target_dir(target), fname)
        src_list = target.get_sources()
        class_list = []
        compiler = self.get_compiler_for_source(src_list[0])
        assert(compiler.get_language() == 'java')
        c = 'c'
        m = ''
        e = ''
        f = 'f'
        main_class = target.get_main_class()
        if main_class != '':
            e = 'e'
        for src in src_list:
            plain_class_path = self.generate_single_java_compile(src, target, compiler, outfile)
            class_list.append(plain_class_path)
        class_dep_list = [os.path.join(self.get_target_private_dir(target), i) for i in class_list]
        jar_rule = 'java_LINKER'
        commands = [c+m+e+f]
        if e != '':
            commands.append(main_class)
        commands.append(self.get_target_filename(target))
        for cls in class_list:
            commands += ['-C', self.get_target_private_dir(target), cls]
        elem = NinjaBuildElement(outname_rel, jar_rule, [])
        elem.add_dep(class_dep_list)
        elem.add_item('ARGS', commands)
        elem.write(outfile)
        self.check_outputs(elem)

    def generate_cs_resource_tasks(self, target, outfile):
        args = []
        deps = []
        for r in target.resources:
            rel_sourcefile = os.path.join(self.build_to_src, target.subdir, r)
            if r.endswith('.resources'):
                a = '-resource:' + rel_sourcefile
            elif r.endswith('.txt') or r.endswith('.resx'):
                ofilebase = os.path.splitext(os.path.basename(r))[0] + '.resources'
                ofilename = os.path.join(self.get_target_private_dir(target), ofilebase)
                elem = NinjaBuildElement(ofilename, "CUSTOM_COMMAND", rel_sourcefile)
                elem.add_item('COMMAND', ['resgen', rel_sourcefile, ofilename])
                elem.add_item('DESC', 'Compiling resource %s.' % rel_sourcefile)
                elem.write(outfile)
                self.check_outputs(elem)
                deps.append(ofilename)
                a = '-resource:' + ofilename
            else:
                raise InvalidArguments('Unknown resource file %s.' % r)
            args.append(a)
        return (args, deps)

    def generate_cs_target(self, target, outfile):
        buildtype = self.environment.coredata.get_builtin_option('buildtype')
        fname = target.get_filename()
        outname_rel = os.path.join(self.get_target_dir(target), fname)
        src_list = target.get_sources()
        compiler = self.get_compiler_for_source(src_list[0])
        assert(compiler.get_language() == 'cs')
        rel_srcs = [s.rel_to_builddir(self.build_to_src) for s in src_list]
        deps = []
        commands = target.extra_args.get('cs', [])
        commands += compiler.get_buildtype_args(buildtype)
        if isinstance(target, build.Executable):
            commands.append('-target:exe')
        elif isinstance(target, build.SharedLibrary):
            commands.append('-target:library')
        else:
            raise MesonException('Unknown C# target type.')
        (resource_args, resource_deps) = self.generate_cs_resource_tasks(target, outfile)
        commands += resource_args
        deps += resource_deps
        commands += compiler.get_output_args(outname_rel)
        for l in target.link_targets:
            lname = os.path.join(self.get_target_dir(l), l.get_filename())
            commands += compiler.get_link_args(lname)
            deps.append(lname)
        if '-g' in commands:
            outputs = [outname_rel, outname_rel + '.mdb']
        else:
            outputs = [outname_rel]
        elem = NinjaBuildElement(outputs, 'cs_COMPILER', rel_srcs)
        elem.add_dep(deps)
        elem.add_item('ARGS', commands)
        self.check_outputs(elem)
        elem.write(outfile)

    def generate_single_java_compile(self, src, target, compiler, outfile):
        args = []
        args += compiler.get_buildtype_args(self.environment.coredata.get_builtin_option('buildtype'))
        args += compiler.get_output_args(self.get_target_private_dir(target))
        for i in target.include_dirs:
            for idir in i.get_incdirs():
                args += ['-sourcepath', os.path.join(self.build_to_src, i.curdir, idir)]
        rel_src = src.rel_to_builddir(self.build_to_src)
        plain_class_path = src.fname[:-4] + 'class'
        rel_obj = os.path.join(self.get_target_private_dir(target), plain_class_path)
        element = NinjaBuildElement(rel_obj, compiler.get_language() + '_COMPILER', rel_src)
        element.add_item('ARGS', args)
        element.write(outfile)
        self.check_outputs(element)
        return plain_class_path

    def generate_java_link(self, outfile):
        rule = 'rule java_LINKER\n'
        command = ' command = jar $ARGS\n'
        description = ' description = Creating jar $out.\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)
        outfile.write('\n')

    def generate_fastvapi_compile(self, target, valac, outfile):
        fastvapis = {}
        for s in target.get_sources():
            if not s.endswith('.vala'):
                continue
            vapibase = os.path.basename(s.fname)[:-4] + 'vapi'
            rel_vapi = os.path.join(self.get_target_private_dir(target), vapibase)
            args = ['--fast-vapi=' + rel_vapi]
            rel_s = s.rel_to_builddir(self.build_to_src)
            element = NinjaBuildElement(rel_vapi, valac.get_language() + '_COMPILER', rel_s)
            element.add_item('ARGS', args)
            element.write(outfile)
            self.check_outputs(element)
            fastvapis[s] = (vapibase, rel_vapi)
        return fastvapis

    def split_vala_sources(self, sources):
        src = []
        vapi_src = []
        for s in sources:
            if s.endswith('.vapi'):
                vapi_src.append(s)
            else:
                src.append(s)
        return (src, vapi_src)

    def generate_vala_compile(self, target, outfile):
        """Vala is compiled into C. Set up all necessary build steps here."""
        valac = self.environment.coredata.compilers['vala']
        fast_vapis = self.generate_fastvapi_compile(target, valac, outfile)
        generated_c = []
        (src, vapi_src) = self.split_vala_sources(target.get_sources())
        vapi_src = [x.rel_to_builddir(self.build_to_src) for x in vapi_src]
        extra_dep_files = []
        for s in src:
            if not s.endswith('.vala'):
                continue
            args = ['-d', self.get_target_private_dir(target)]
            sc = os.path.basename(s.fname)[:-4] + 'c'
            args += ['-C']
            vapi_order_deps = []
            for (sourcefile, vapi_info) in fast_vapis.items():
                if sourcefile == s:
                    continue
                (vapibase, rel_vapi) = vapi_info
                args += ['--use-fast-vapi=' + rel_vapi]
                vapi_order_deps.append(rel_vapi)
            relsc = os.path.join(self.get_target_private_dir(target), sc)
            rel_s = s.rel_to_builddir(self.build_to_src)
            args += ['--deps', relsc + '.d']
            if self.environment.coredata.get_builtin_option('werror'):
                args += valac.get_werror_args()
            for d in target.external_deps:
                if isinstance(d, dependencies.PkgConfigDependency):
                    if d.name == 'glib-2.0' and d.version_requirement is not None \
                        and d.version_requirement.startswith(('>=', '==')):
                            args += ['--target-glib', d.version_requirement[2:]]
                    args += ['--pkg', d.name]
            args += vapi_src
            extra_args = []

            for a in target.extra_args.get('vala', []):
                if isinstance(a, File):
                    relname = a.rel_to_builddir(self.build_to_src)
                    extra_dep_files.append(relname)
                    extra_args.append(relname)
                else:
                    extra_args.append(a)
            args += extra_args
            generated_c += [relsc]
            element = NinjaBuildElement(relsc, valac.get_language() + '_COMPILER', rel_s)
            element.add_item('ARGS', args)
            element.add_orderdep(vapi_order_deps)
            element.add_dep(extra_dep_files)
            element.write(outfile)
            self.check_outputs(element)
        return generated_c

    def generate_rust_target(self, target, outfile):
        rustc = self.environment.coredata.compilers['rust']
        relsrc = []
        for i in target.get_sources():
            if not rustc.can_compile(i):
                raise InvalidArguments('Rust target %s contains a non-rust source file.' % target.get_basename())
            relsrc.append(i.rel_to_builddir(self.build_to_src))
        target_name = os.path.join(target.subdir, target.get_filename())
        args = ['--crate-type']
        if isinstance(target, build.Executable):
            cratetype = 'bin'
        elif isinstance(target, build.SharedLibrary):
            cratetype = 'rlib'
        elif isinstance(target, build.StaticLibrary):
            cratetype = 'rlib'
        else:
            raise InvalidArguments('Unknown target type for rustc.')
        args.append(cratetype)
        args += rustc.get_buildtype_args(self.environment.coredata.get_builtin_option('buildtype'))
        depfile = target.name + '.d'
        args += ['--out-dir', target.subdir]
        args += ['--emit', 'dep-info', '--emit', 'link']
        orderdeps = [os.path.join(t.subdir, t.get_filename()) for t in target.link_targets]
        linkdirs = {}
        for d in target.link_targets:
            linkdirs[d.subdir] = True
        for d in linkdirs.keys():
            if d == '':
                d = '.'
            args += ['-L', d]
        element = NinjaBuildElement(target_name, 'rust_COMPILER', relsrc)
        if len(orderdeps) > 0:
            element.add_orderdep(orderdeps)
        element.add_item('ARGS', args)
        element.add_item('targetdep', depfile)
        element.add_item('cratetype', cratetype)
        element.write(outfile)
        self.check_outputs(element)

    def swift_module_file_name(self, target):
        return os.path.join(self.get_target_private_dir(target),
                            self.target_swift_modulename(target) + '.swiftmodule')

    def target_swift_modulename(self, target):
        return target.name

    def is_swift_target(self, target):
        for s in target.sources:
            if s.endswith('swift'):
                return True
        return False

    def determine_swift_dep_modules(self, target):
        result = []
        for l in target.link_targets:
            if self.is_swift_target(l):
                result.append(self.swift_module_file_name(l))
        return result

    def determine_swift_dep_dirs(self, target):
        result = []
        for l in target.link_targets:
            result.append(self.get_target_private_dir_abs(l))
        return result

    def get_swift_link_deps(self, target):
        result = []
        for l in target.link_targets:
            result.append(self.get_target_filename(l))
        return result

    def split_swift_generated_sources(self, target):
        all_srcs = []
        for genlist in target.get_generated_sources():
            if isinstance(genlist, build.CustomTarget):
                for ifile in genlist.get_filename():
                    rel = os.path.join(self.get_target_dir(genlist), ifile)
                    all_srcs.append(rel)
            else:
                for ifile in genlist.get_outfilelist():
                    rel = os.path.join(self.get_target_private_dir(target), ifile)
                    all_srcs.append(rel)
        srcs = []
        others = []
        for i in all_srcs:
            if i.endswith('.swift'):
                srcs.append(i)
            else:
                others.append(i)
        return (srcs, others)

    def generate_swift_target(self, target, outfile):
        module_name = self.target_swift_modulename(target)
        swiftc = self.environment.coredata.compilers['swift']
        abssrc = []
        abs_headers = []
        header_imports = []
        for i in target.get_sources():
            if swiftc.can_compile(i):
                relsrc = i.rel_to_builddir(self.build_to_src)
                abss = os.path.normpath(os.path.join(self.environment.get_build_dir(), relsrc))
                abssrc.append(abss)
            elif self.environment.is_header(i):
                relh = i.rel_to_builddir(self.build_to_src)
                absh = os.path.normpath(os.path.join(self.environment.get_build_dir(), relh))
                abs_headers.append(absh)
                header_imports += swiftc.get_header_import_args(absh)
            else:
                raise InvalidArguments('Swift target %s contains a non-swift source file.' % target.get_basename())
        os.makedirs(self.get_target_private_dir_abs(target), exist_ok=True)
        compile_args = swiftc.get_compile_only_args()
        compile_args += swiftc.get_module_args(module_name)
        link_args = swiftc.get_output_args(os.path.join(self.environment.get_build_dir(), self.get_target_filename(target)))
        rundir = self.get_target_private_dir(target)
        out_module_name = self.swift_module_file_name(target)
        in_module_files = self.determine_swift_dep_modules(target)
        abs_module_dirs = self.determine_swift_dep_dirs(target)
        module_includes = []
        for x in abs_module_dirs:
            module_includes += swiftc.get_include_args(x)
        link_deps = self.get_swift_link_deps(target)
        abs_link_deps = [os.path.join(self.environment.get_build_dir(), x) for x in link_deps]
        (rel_generated, _) = self.split_swift_generated_sources(target)
        abs_generated = [os.path.join(self.environment.get_build_dir(), x) for x in rel_generated]
        # We need absolute paths because swiftc needs to be invoked in a subdir
        # and this is the easiest way about it.
        objects = [] # Relative to swift invocation dir
        rel_objects = [] # Relative to build.ninja
        for i in abssrc + abs_generated:
            base = os.path.split(i)[1]
            oname = os.path.splitext(base)[0] + '.o'
            objects.append(oname)
            rel_objects.append(os.path.join(self.get_target_private_dir(target), oname))

        # Swiftc does not seem to be able to emit objects and module files in one go.
        elem = NinjaBuildElement(rel_objects,
                                 'swift_COMPILER',
                                 abssrc)
        elem.add_dep(in_module_files + rel_generated)
        elem.add_dep(abs_headers)
        elem.add_item('ARGS', compile_args + header_imports + abs_generated + module_includes)
        elem.add_item('RUNDIR', rundir)
        elem.write(outfile)
        self.check_outputs(elem)
        elem = NinjaBuildElement(out_module_name,
                                 'swift_COMPILER',
                                 abssrc)
        elem.add_dep(in_module_files + rel_generated)
        elem.add_item('ARGS', compile_args + abs_generated + module_includes + swiftc.get_mod_gen_args())
        elem.add_item('RUNDIR', rundir)
        elem.write(outfile)
        self.check_outputs(elem)
        if isinstance(target, build.StaticLibrary):
            elem = self.generate_link(target, outfile, self.get_target_filename(target),
                               rel_objects, self.build.static_linker)
            elem.write(outfile)
        elif isinstance(target, build.Executable):
            elem = NinjaBuildElement(self.get_target_filename(target), 'swift_COMPILER', [])
            elem.add_dep(rel_objects)
            elem.add_dep(link_deps)
            elem.add_item('ARGS', link_args + swiftc.get_std_exe_link_args() + objects + abs_link_deps)
            elem.add_item('RUNDIR', rundir)
            elem.write(outfile)
            self.check_outputs(elem)
        else:
            raise MesonException('Swift supports only executable and static library targets.')

    def generate_static_link_rules(self, is_cross, outfile):
        if self.build.has_language('java'):
            if not is_cross:
                self.generate_java_link(outfile)
        if is_cross:
            if self.environment.cross_info.need_cross_compiler():
                static_linker = self.build.static_cross_linker
            else:
                static_linker = self.build.static_linker
            crstr = '_CROSS'
        else:
            static_linker = self.build.static_linker
            crstr = ''
        if static_linker is None:
            return
        rule = 'rule STATIC%s_LINKER\n' % crstr
        if mesonlib.is_windows():
            command_templ = ''' command = %s @$out.rsp
 rspfile = $out.rsp
 rspfile_content = $LINK_ARGS %s $in
'''
        else:
            command_templ = ' command = %s $LINK_ARGS %s $in\n'
        command = command_templ %\
        (' '.join(static_linker.get_exelist()),
         ' '.join(static_linker.get_output_args('$out')))
        description = ' description = Static linking library $out\n\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)

    def generate_dynamic_link_rules(self, outfile):
        ctypes = [(self.build.compilers, False)]
        if self.environment.is_cross_build():
            if self.environment.cross_info.need_cross_compiler():
                ctypes.append((self.build.cross_compilers, True))
            else:
                # Native compiler masquerades as the cross compiler.
                ctypes.append((self.build.compilers, True))
        else:
            ctypes.append((self.build.cross_compilers, True))
        for (complist, is_cross) in ctypes:
            for compiler in complist:
                langname = compiler.get_language()
                if langname == 'java' or langname == 'vala' or\
                 langname == 'rust' or langname == 'cs':
                    continue
                crstr = ''
                cross_args = []
                if is_cross:
                    crstr = '_CROSS'
                    try:
                        cross_args = self.environment.cross_info.config['properties'][langname + '_link_args']
                    except KeyError:
                        pass
                rule = 'rule %s%s_LINKER\n' % (langname, crstr)
                if mesonlib.is_windows():
                    command_template = ''' command = %s @$out.rsp
 rspfile = $out.rsp
 rspfile_content = %s $ARGS  %s $in $LINK_ARGS $aliasing
'''
                else:
                    command_template = ' command = %s %s $ARGS  %s $in $LINK_ARGS $aliasing\n'
                command = command_template % \
                (' '.join(compiler.get_linker_exelist()),\
                 ' '.join(cross_args),\
                 ' '.join(compiler.get_linker_output_args('$out')))
                description = ' description = Linking target $out'
                outfile.write(rule)
                outfile.write(command)
                outfile.write(description)
                outfile.write('\n')
        scriptdir = self.environment.get_script_dir()
        outfile.write('\n')
        symrule = 'rule SHSYM\n'
        symcmd = ' command = "%s" "%s" %s %s $CROSS\n' % (ninja_quote(sys.executable),
                                         ninja_quote(os.path.join(scriptdir, 'symbolextractor.py')),
                                         '$in', '$out')
        synstat = ' restat = 1\n'
        syndesc = ' description = Generating symbol file $out.\n'
        outfile.write(symrule)
        outfile.write(symcmd)
        outfile.write(synstat)
        outfile.write(syndesc)
        outfile.write('\n')

    def generate_java_compile_rule(self, compiler, outfile):
        rule = 'rule %s_COMPILER\n' % compiler.get_language()
        invoc = ' '.join([ninja_quote(i) for i in compiler.get_exelist()])
        command = ' command = %s $ARGS $in\n' % invoc
        description = ' description = Compiling Java object $in.\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)
        outfile.write('\n')

    def generate_cs_compile_rule(self, compiler, outfile):
        rule = 'rule %s_COMPILER\n' % compiler.get_language()
        invoc = ' '.join([ninja_quote(i) for i in compiler.get_exelist()])
        command = ' command = %s $ARGS $in\n' % invoc
        description = ' description = Compiling cs target $out.\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)
        outfile.write('\n')

    def generate_vala_compile_rules(self, compiler, outfile):
        rule = 'rule %s_COMPILER\n' % compiler.get_language()
        invoc = ' '.join([ninja_quote(i) for i in compiler.get_exelist()])
        command = ' command = %s $ARGS $in\n' % invoc
        description = ' description = Compiling Vala source $in.\n'
        restat = ' restat = 1\n' # ValaC does this always to take advantage of it.
        depfile = ' depfile = $out.d\n'
        depstyle = ' deps = gcc\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)
        outfile.write(restat)
        outfile.write(depfile)
        outfile.write(depstyle)
        outfile.write('\n')

    def generate_rust_compile_rules(self, compiler, outfile):
        rule = 'rule %s_COMPILER\n' % compiler.get_language()
        invoc = ' '.join([ninja_quote(i) for i in compiler.get_exelist()])
        command = ' command = %s $ARGS $in\n' % invoc
        description = ' description = Compiling Rust source $in.\n'
        depfile = ' depfile = $targetdep\n'

        depstyle = ' deps = gcc\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)
        outfile.write(depfile)
        outfile.write(depstyle)
        outfile.write('\n')

    def generate_swift_compile_rules(self, compiler, outfile):
        rule = 'rule %s_COMPILER\n' % compiler.get_language()
        full_exe = [sys.executable,
                    os.path.join(self.environment.get_script_dir(), 'dirchanger.py'),
                    '$RUNDIR'] + compiler.get_exelist()
        invoc = ' '.join([ninja_quote(i) for i in full_exe])
        command = ' command = %s $ARGS $in\n' % invoc
        description = ' description = Compiling Swift source $in.\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(description)
        outfile.write('\n')

    def generate_fortran_dep_hack(self, outfile):
        if mesonlib.is_windows():
            cmd = 'cmd /C ""'
        else:
            cmd = 'true'
        template = '''# Workaround for these issues:
# https://groups.google.com/forum/#!topic/ninja-build/j-2RfBIOd_8
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485
rule FORTRAN_DEP_HACK
 command = %s
 description = Dep hack
 restat = 1

'''
        outfile.write(template % cmd)

    def generate_compile_rule_for(self, langname, compiler, qstr, is_cross, outfile):
        if langname == 'java':
            if not is_cross:
                self.generate_java_compile_rule(compiler, outfile)
            return
        if langname == 'cs':
            if not is_cross:
                self.generate_cs_compile_rule(compiler, outfile)
            return
        if langname == 'vala':
            if not is_cross:
                self.generate_vala_compile_rules(compiler, outfile)
            return
        if langname == 'rust':
            if not is_cross:
                self.generate_rust_compile_rules(compiler, outfile)
            return
        if langname == 'swift':
            if not is_cross:
                self.generate_swift_compile_rules(compiler, outfile)
            return
        if langname == 'fortran':
            self.generate_fortran_dep_hack(outfile)
        if is_cross:
            crstr = '_CROSS'
        else:
            crstr = ''
        rule = 'rule %s%s_COMPILER\n' % (langname, crstr)
        depargs = compiler.get_dependency_gen_args('$out', '$DEPFILE')
        quoted_depargs = []
        for d in depargs:
            if d != '$out' and d != '$in':
                d = qstr % d
            quoted_depargs.append(d)
        cross_args = []
        if is_cross:
            try:
                cross_args = self.environment.cross_info.config['properties'][langname + '_args']
            except KeyError:
                pass
        if mesonlib.is_windows():
            command_template = ''' command = %s @$out.rsp
 rspfile = $out.rsp
 rspfile_content = %s $ARGS %s %s %s $in
'''
        else:
            command_template = ' command = %s %s $ARGS %s %s %s $in\n'
        command = command_template % \
            (' '.join(compiler.get_exelist()),\
             ' '.join(cross_args),
             ' '.join(quoted_depargs),\
             ' '.join(compiler.get_output_args('$out')),\
             ' '.join(compiler.get_compile_only_args()))
        description = ' description = Compiling %s object $out\n' % langname
        if compiler.get_id() == 'msvc':
            deps = ' deps = msvc\n'
        else:
            deps = ' deps = gcc\n'
            deps += ' depfile = $DEPFILE\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(deps)
        outfile.write(description)
        outfile.write('\n')

    def generate_pch_rule_for(self, langname, compiler, qstr, is_cross, outfile):
        if langname != 'c' and langname != 'cpp':
            return
        if is_cross:
            crstr = '_CROSS'
        else:
            crstr = ''
        rule = 'rule %s%s_PCH\n' % (langname, crstr)
        depargs = compiler.get_dependency_gen_args('$out', '$DEPFILE')
        cross_args = []
        if is_cross:
            try:
                cross_args = self.environment.cross_info.config['properties'][langname + '_args']
            except KeyError:
                pass

        quoted_depargs = []
        for d in depargs:
            if d != '$out' and d != '$in':
                d = qstr % d
            quoted_depargs.append(d)
        if compiler.get_id() == 'msvc':
            output = ''
        else:
            output = ' '.join(compiler.get_output_args('$out'))
        command = " command = %s %s $ARGS %s %s %s $in\n" % \
            (' '.join(compiler.get_exelist()),\
             ' '.join(cross_args),\
             ' '.join(quoted_depargs),\
             output,\
             ' '.join(compiler.get_compile_only_args()))
        description = ' description = Precompiling header %s\n' % '$in'
        if compiler.get_id() == 'msvc':
            deps = ' deps = msvc\n'
        else:
            deps = ' deps = gcc\n'
            deps += ' depfile = $DEPFILE\n'
        outfile.write(rule)
        outfile.write(command)
        outfile.write(deps)
        outfile.write(description)
        outfile.write('\n')

    def generate_compile_rules(self, outfile):
        qstr = quote_char + "%s" + quote_char
        for compiler in self.build.compilers:
            langname = compiler.get_language()
            self.generate_compile_rule_for(langname, compiler, qstr, False, outfile)
            self.generate_pch_rule_for(langname, compiler, qstr, False, outfile)
        if self.environment.is_cross_build():
            # In case we are going a target-only build, make the native compilers
            # masquerade as cross compilers.
            if self.environment.cross_info.need_cross_compiler():
                cclist = self.build.cross_compilers
            else:
                cclist = self.build.compilers
            for compiler in cclist:
                langname = compiler.get_language()
                self.generate_compile_rule_for(langname, compiler, qstr, True, outfile)
                self.generate_pch_rule_for(langname, compiler, qstr, True, outfile)
        outfile.write('\n')

    def replace_outputs(self, args, private_dir, output_list):
        newargs = []
        regex = re.compile('@OUTPUT(\d+)@')
        for arg in args:
            m = regex.search(arg)
            while m is not None:
                index = int(m.group(1))
                src = '@OUTPUT%d@' % index
                arg = arg.replace(src, os.path.join(private_dir, output_list[index]))
                m = regex.search(arg)
            newargs.append(arg)
        return newargs

    def generate_custom_generator_rules(self, target, outfile):
        for genlist in target.get_generated_sources():
            if isinstance(genlist, build.CustomTarget):
                continue # Customtarget has already written its output rules
            generator = genlist.get_generator()
            exe = generator.get_exe()
            exe_arr = self.exe_object_to_cmd_array(exe)
            infilelist = genlist.get_infilelist()
            outfilelist = genlist.get_outfilelist()
            base_args = generator.get_arglist()
            extra_dependencies = [os.path.join(self.build_to_src, i) for i in genlist.extra_depends]
            for i in range(len(infilelist)):
                if len(generator.outputs) == 1:
                    sole_output = os.path.join(self.get_target_private_dir(target), outfilelist[i])
                else:
                    sole_output = ''
                curfile = infilelist[i]
                infilename = os.path.join(self.build_to_src, curfile)
                outfiles = genlist.get_outputs_for(curfile)
                outfiles = [os.path.join(self.get_target_private_dir(target), of) for of in outfiles]
                args = [x.replace("@INPUT@", infilename).replace('@OUTPUT@', sole_output)\
                        for x in base_args]
                args = self.replace_outputs(args, self.get_target_private_dir(target), outfilelist)
                # We have consumed output files, so drop them from the list of remaining outputs.
                if sole_output == '':
                    outfilelist = outfilelist[len(generator.outputs):]
                relout = self.get_target_private_dir(target)
                args = [x.replace("@SOURCE_DIR@", self.build_to_src).replace("@BUILD_DIR@", relout)
                        for x in args]
                final_args = []
                for a in args:
                    if a == '@EXTRA_ARGS@':
                        final_args += genlist.get_extra_args()
                    else:
                        final_args.append(a)
                cmdlist = exe_arr + final_args
                elem = NinjaBuildElement(outfiles, 'CUSTOM_COMMAND', infilename)
                if len(extra_dependencies) > 0:
                    elem.add_dep(extra_dependencies)
                elem.add_item('DESC', 'Generating $out')
                if isinstance(exe, build.BuildTarget):
                    elem.add_dep(self.get_target_filename(exe))
                elem.add_item('COMMAND', cmdlist)
                elem.write(outfile)
                self.check_outputs(elem)

    def scan_fortran_module_outputs(self, target):
        compiler = None
        for c in self.build.compilers:
            if c.get_language() == 'fortran':
                compiler = c
                break
        if compiler is None:
            self.fortran_deps[target.get_basename()] = {}
            return
        modre = re.compile(r"\s*module\s+(\w+)", re.IGNORECASE)
        module_files = {}
        for s in target.get_sources():
            # FIXME, does not work for generated Fortran sources,
            # but those are really rare. I hope.
            if not compiler.can_compile(s):
                continue
            for line in open(os.path.join(self.environment.get_source_dir(), s.subdir, s.fname)):
                modmatch = modre.match(line)
                if modmatch is not None:
                    modname = modmatch.group(1)
                    if modname.lower() == 'procedure': # MODULE PROCEDURE construct
                        continue
                    if modname in module_files:
                        raise InvalidArguments('Namespace collision: module %s defined in two files %s and %s.' %
                                               (modname, module_files[modname], s))
                    module_files[modname] = s
        self.fortran_deps[target.get_basename()] = module_files

    def get_fortran_deps(self, compiler, src, target):
        mod_files = []
        usere = re.compile(r"\s*use\s+(\w+)", re.IGNORECASE)
        dirname = self.get_target_private_dir(target)
        tdeps= self.fortran_deps[target.get_basename()]
        for line in open(src):
            usematch = usere.match(line)
            if usematch is not None:
                usename = usematch.group(1)
                if usename not in tdeps:
                    # The module is not provided by any source file. This is due to
                    # a) missing file/typo/etc
                    # b) using a module provided by the compiler, such as OpenMP
                    # There's no easy way to tell which is which (that I know of)
                    # so just ignore this and go on. Ideally we would print a
                    # warning message to the user but this is a common occurrance,
                    # which would lead to lots of distracting noise.
                    continue
                mod_source_file = tdeps[usename]
                # Check if a source uses a module it exports itself.
                # Potential bug if multiple targets have a file with
                # the same name.
                if mod_source_file.fname == os.path.split(src)[1]:
                    continue
                mod_name = compiler.module_name_to_filename(usematch.group(1))
                mod_files.append(os.path.join(dirname, mod_name))
        return mod_files

    def generate_single_compile(self, target, outfile, src, is_generated=False, header_deps=[], order_deps=[]):
        if(isinstance(src, str) and src.endswith('.h')):
            raise RuntimeError('Fug')
        if isinstance(src, RawFilename) and src.fname.endswith('.h'):
            raise RuntimeError('Fug')
        extra_orderdeps = []
        compiler = self.get_compiler_for_source(src)
        commands = self.generate_basic_compiler_args(target, compiler)
        commands += compiler.get_include_args(self.get_target_private_dir(target), False)
        curdir = target.get_subdir()
        tmppath = os.path.normpath(os.path.join(self.build_to_src, curdir))
        commands += compiler.get_include_args(tmppath, False)
        if curdir ==  '':
            curdir = '.'
        commands += compiler.get_include_args(curdir, False)
        for d in target.external_deps:
            if d.need_threads():
                commands += compiler.thread_flags()
                break
        if isinstance(src, RawFilename):
            rel_src = src.fname
        elif is_generated:
            if self.has_dir_part(src):
                rel_src = src
            else:
                rel_src = os.path.join(self.get_target_private_dir(target), src)
                abs_src = os.path.join(self.environment.get_source_dir(), rel_src)
        else:
            if isinstance(src, File):
                rel_src = src.rel_to_builddir(self.build_to_src)
            else:
                raise build.InvalidArguments('Invalid source type.')
            abs_src = os.path.join(self.environment.get_build_dir(), rel_src)
        if isinstance(src, RawFilename):
            src_filename = src.fname
        elif isinstance(src, File):
            src_filename = src.fname
        elif os.path.isabs(src):
            src_filename = os.path.basename(src)
        else:
            src_filename = src
        obj_basename = src_filename.replace('/', '_').replace('\\', '_')
        rel_obj = os.path.join(self.get_target_private_dir(target), obj_basename)
        rel_obj += '.' + self.environment.get_object_suffix()
        dep_file = compiler.depfile_for_object(rel_obj)
        if self.environment.coredata.get_builtin_option('use_pch'):
            pchlist = target.get_pch(compiler.language)
        else:
            pchlist = []
        if len(pchlist) == 0:
            pch_dep = []
        else:
            arr = []
            i = os.path.join(self.get_target_private_dir(target), compiler.get_pch_name(pchlist[0]))
            arr.append(i)
            pch_dep = arr
        for i in target.get_include_dirs():
            basedir = i.get_curdir()
            for d in i.get_incdirs():
                expdir =  os.path.join(basedir, d)
                srctreedir = os.path.join(self.build_to_src, expdir)
                bargs = compiler.get_include_args(expdir, i.is_system)
                sargs = compiler.get_include_args(srctreedir, i.is_system)
                commands += bargs
                commands += sargs
            for d in i.get_extra_build_dirs():
                commands += compiler.get_include_args(d, i.is_system)
        custom_target_include_dirs = []
        for i in target.generated:
            if isinstance(i, build.CustomTarget):
                idir = self.get_target_dir(i)
                if idir not in custom_target_include_dirs:
                    custom_target_include_dirs.append(idir)
        for i in custom_target_include_dirs:
            commands+= compiler.get_include_args(i, False)
        if self.environment.coredata.get_builtin_option('use_pch'):
            commands += self.get_pch_include_args(compiler, target)
        crstr = ''
        if target.is_cross:
            crstr = '_CROSS'
        compiler_name = '%s%s_COMPILER' % (compiler.get_language(), crstr)
        extra_deps = []
        if compiler.get_language() == 'fortran':
            extra_deps += self.get_fortran_deps(compiler, abs_src, target)
            # Dependency hack. Remove once multiple outputs in Ninja is fixed:
            # https://groups.google.com/forum/#!topic/ninja-build/j-2RfBIOd_8
            for modname, srcfile in self.fortran_deps[target.get_basename()].items():
                modfile = os.path.join(self.get_target_private_dir(target),
                                       compiler.module_name_to_filename(modname))
                if srcfile == src:
                    depelem = NinjaBuildElement(modfile, 'FORTRAN_DEP_HACK', rel_obj)
                    depelem.write(outfile)
                    self.check_outputs(depelem)
            commands += compiler.get_module_outdir_args(self.get_target_private_dir(target))

        element = NinjaBuildElement(rel_obj, compiler_name, rel_src)
        for d in header_deps:
            if isinstance(d, RawFilename):
                d = d.fname
            elif not self.has_dir_part(d):
                d = os.path.join(self.get_target_private_dir(target), d)
            element.add_dep(d)
        for d in extra_deps:
            element.add_dep(d)
        for d in order_deps:
            if isinstance(d, RawFilename):
                d = d.fname
            elif not self.has_dir_part(d):
                d = os.path.join(self.get_target_private_dir(target), d)
            element.add_orderdep(d)
        element.add_orderdep(pch_dep)
        element.add_orderdep(extra_orderdeps)
        for i in self.get_fortran_orderdeps(target, compiler):
            element.add_orderdep(i)
        element.add_item('DEPFILE', dep_file)
        element.add_item('ARGS', commands)
        element.write(outfile)
        self.check_outputs(element)
        return rel_obj

    def has_dir_part(self, fname):
        return '/' in fname or '\\' in fname

    # Fortran is a bit weird (again). When you link against a library, just compiling a source file
    # requires the mod files that are output when single files are built. To do this right we would need to
    # scan all inputs and write out explicit deps for each file. That is stoo slow and too much effort so
    # instead just have an ordered dependendy on the library. This ensures all required mod files are created.
    # The real deps are then detected via dep file generation from the compiler. This breaks on compilers that
    # produce incorrect dep files but such is life.
    def get_fortran_orderdeps(self, target, compiler):
        if compiler.language != 'fortran':
            return []
        return [os.path.join(self.get_target_dir(lt), lt.get_filename()) for lt in target.link_targets]

    def generate_msvc_pch_command(self, target, compiler, pch):
        if len(pch) != 2:
            raise RuntimeError('MSVC requires one header and one source to produce precompiled headers.')
        header = pch[0]
        source = pch[1]
        pchname = compiler.get_pch_name(header)
        dst = os.path.join(self.get_target_private_dir(target), pchname)

        commands = []
        commands += self.generate_basic_compiler_args(target, compiler)
        just_name = os.path.split(header)[1]
        (objname, pch_args) = compiler.gen_pch_args(just_name, source, dst)
        commands += pch_args
        dep = dst + '.' + compiler.get_depfile_suffix()
        return (commands, dep, dst, [objname])

    def generate_gcc_pch_command(self, target, compiler, pch):
        commands = []
        commands += self.generate_basic_compiler_args(target, compiler)
        dst = os.path.join(self.get_target_private_dir(target),
                           os.path.split(pch)[-1] + '.' + compiler.get_pch_suffix())
        dep = dst + '.' + compiler.get_depfile_suffix()
        return (commands, dep, dst, []) # Gcc does not create an object file during pch generation.

    def generate_pch(self, target, outfile):
        cstr = ''
        pch_objects = []
        if target.is_cross:
            cstr = '_CROSS'
        for lang in ['c', 'cpp']:
            pch = target.get_pch(lang)
            if len(pch) == 0:
                continue
            if '/' not in pch[0] or '/' not in pch[-1]:
                raise build.InvalidArguments('Precompiled header of "%s" must not be in the same directory as source, please put it in a subdirectory.' % target.get_basename())
            compiler = self.get_compiler_for_lang(lang)
            if compiler.id == 'msvc':
                src = os.path.join(self.build_to_src, target.get_source_subdir(), pch[-1])
                (commands, dep, dst, objs) = self.generate_msvc_pch_command(target, compiler, pch)
                extradep = os.path.join(self.build_to_src, target.get_source_subdir(), pch[0])
            else:
                src = os.path.join(self.build_to_src, target.get_source_subdir(), pch[0])
                (commands, dep, dst, objs) = self.generate_gcc_pch_command(target, compiler, pch[0])
                extradep = None
            pch_objects += objs
            rulename = compiler.get_language() + cstr + '_PCH'
            elem = NinjaBuildElement(dst, rulename, src)
            if extradep is not None:
                elem.add_dep(extradep)
            elem.add_item('ARGS', commands)
            elem.add_item('DEPFILE', dep)
            elem.write(outfile)
            self.check_outputs(elem)
        return pch_objects

    def generate_shsym(self, outfile, target):
        target_name = self.get_target_filename(target)
        targetdir = self.get_target_private_dir(target)
        symname = os.path.join(targetdir, target_name + '.symbols')
        elem = NinjaBuildElement(symname, 'SHSYM', target_name)
        if self.environment.is_cross_build() and self.environment.cross_info.need_cross_compiler():
            elem.add_item('CROSS', '--cross-host=' + self.environment.cross_info.config['host_machine']['system'])
        elem.write(outfile)
        self.check_outputs(elem)

    def generate_link(self, target, outfile, outname, obj_list, linker, extra_args=[]):
        if isinstance(target, build.StaticLibrary):
            linker_base = 'STATIC'
        else:
            linker_base = linker.get_language() # Fixme.
        if isinstance(target, build.SharedLibrary):
            self.generate_shsym(outfile, target)
        crstr = ''
        if target.is_cross:
            crstr = '_CROSS'
        linker_rule = linker_base + crstr + '_LINKER'
        abspath = os.path.join(self.environment.get_build_dir(), target.subdir)
        commands = []
        commands += linker.get_linker_always_args()
        commands += linker.get_buildtype_linker_args(self.environment.coredata.get_builtin_option('buildtype'))
        commands += linker.get_option_link_args(self.environment.coredata.compiler_options)
        if not(isinstance(target, build.StaticLibrary)):
            commands += self.environment.coredata.external_link_args[linker.get_language()]
        if isinstance(target, build.Executable):
            commands += linker.get_std_exe_link_args()
        elif isinstance(target, build.SharedLibrary):
            commands += linker.get_std_shared_lib_link_args()
            commands += linker.get_pic_args()
            if hasattr(target, 'soversion'):
                soversion = target.soversion
            else:
                soversion = None
            commands += linker.get_soname_args(target.name, abspath, soversion)
        elif isinstance(target, build.StaticLibrary):
            commands += linker.get_std_link_args()
        else:
            raise RuntimeError('Unknown build target type.')
        # Link arguments of static libraries are not put in the command line of
        # the library. They are instead appended to the command line where
        # the static library is used.
        if linker_base == 'STATIC':
            dependencies = []
        else:
            dependencies = target.get_dependencies()
        commands += self.build_target_link_arguments(linker, dependencies)
        for d in target.external_deps:
            if d.need_threads():
                commands += linker.thread_link_flags()
        if not isinstance(target, build.StaticLibrary):
            commands += target.link_args
        # External deps must be last because target link libraries may depend on them.
        if not(isinstance(target, build.StaticLibrary)):
            for dep in target.get_external_deps():
                commands += dep.get_link_args()
            for d in target.get_dependencies():
                if isinstance(d, build.StaticLibrary):
                    for dep in d.get_external_deps():
                        commands += dep.get_link_args()
        commands += linker.build_rpath_args(self.environment.get_build_dir(),\
                                            self.determine_rpath_dirs(target), target.install_rpath)
        if self.environment.coredata.get_builtin_option('coverage'):
            commands += linker.get_coverage_link_args()
        custom_target_libraries = self.get_custom_target_provided_libraries(target)
        commands += extra_args
        commands += custom_target_libraries
        commands = linker.unixtype_flags_to_native(commands)
        dep_targets = [self.get_dependency_filename(t) for t in dependencies]
        dep_targets += [os.path.join(self.environment.source_dir,
                                     target.subdir, t) for t in target.link_depends]
        elem = NinjaBuildElement(outname, linker_rule, obj_list)
        elem.add_dep(dep_targets + custom_target_libraries)
        elem.add_item('LINK_ARGS', commands)
        self.check_outputs(elem)
        return elem

    def get_custom_target_provided_libraries(self, target):
        libs = []
        for t in target.get_generated_sources():
            if not isinstance(t, build.CustomTarget):
                continue
            for f in t.output:
                if self.environment.is_library(f):
                    libs.append(os.path.join(self.get_target_dir(t), f))
        return libs

    def determine_rpath_dirs(self, target):
        link_deps = target.get_all_link_deps()
        result = []
        for ld in link_deps:
            prospective = self.get_target_dir(ld)
            if not prospective in result:
                result.append(prospective)
        return result

    def get_dependency_filename(self, t):
        if isinstance(t, build.SharedLibrary):
            return os.path.join(self.get_target_private_dir(t), self.get_target_filename(t) + '.symbols')
        return self.get_target_filename(t)

    def generate_shlib_aliases(self, target, outdir):
        basename = target.get_filename()
        aliases = target.get_aliaslist()
        if not mesonlib.is_windows():
            for alias in aliases:
                aliasfile = os.path.join(self.environment.get_build_dir(), outdir, alias)
                try:
                    os.remove(aliasfile)
                except Exception:
                    pass
                os.symlink(basename, aliasfile)
        else:
            mlog.debug("Library versioning disabled because host does not support symlinks.")

    def generate_gcov_clean(self, outfile):
            gcno_elem = NinjaBuildElement('clean-gcno', 'CUSTOM_COMMAND', 'PHONY')
            script_root = self.environment.get_script_dir()
            clean_script = os.path.join(script_root, 'delwithsuffix.py')
            gcno_elem.add_item('COMMAND', [sys.executable, clean_script, '.', 'gcno'])
            gcno_elem.add_item('description', 'Deleting gcno files')
            gcno_elem.write(outfile)
            self.check_outputs(gcno_elem)

            gcda_elem = NinjaBuildElement('clean-gcda', 'CUSTOM_COMMAND', 'PHONY')
            script_root = self.environment.get_script_dir()
            clean_script = os.path.join(script_root, 'delwithsuffix.py')
            gcda_elem.add_item('COMMAND', [sys.executable, clean_script, '.', 'gcda'])
            gcda_elem.add_item('description', 'Deleting gcda files')
            gcda_elem.write(outfile)
            self.check_outputs(gcda_elem)

    def is_compilable_file(self, filename):
        if filename.endswith('.cpp') or\
        filename.endswith('.c') or\
        filename.endswith('.cxx') or\
        filename.endswith('.cc') or\
        filename.endswith('.C'):
            return True
        return False

    def process_dep_gens(self, outfile, target):
        src_deps = []
        other_deps = []
        for rule in self.dep_rules.values():
            srcs = target.get_original_kwargs().get(rule.src_keyword, [])
            if isinstance(srcs, str):
                srcs = [srcs]
            for src in srcs:
                plainname = os.path.split(src)[1]
                basename = plainname.split('.')[0]
                outname = rule.name_templ.replace('@BASENAME@', basename).replace('@PLAINNAME@', plainname)
                outfilename = os.path.join(self.get_target_private_dir(target), outname)
                infilename = os.path.join(self.build_to_src, target.get_source_subdir(), src)
                elem = NinjaBuildElement(outfilename, rule.name, infilename)
                elem.write(outfile)
                self.check_outputs(elem)
                if self.is_compilable_file(outfilename):
                    src_deps.append(outfilename)
                else:
                    other_deps.append(outfilename)
        return (src_deps, other_deps)

    def generate_ending(self, outfile):
        targetlist = [self.get_target_filename(t) for t in self.build.get_targets().values()\
                      if not isinstance(t, build.RunTarget)]

        elem = NinjaBuildElement('all', 'phony', targetlist)
        elem.write(outfile)
        self.check_outputs(elem)

        default = 'default all\n\n'
        outfile.write(default)

        ninja_command = environment.detect_ninja()
        if ninja_command is None:
            raise MesonException('Could not detect ninja command')
        elem = NinjaBuildElement('clean', 'CUSTOM_COMMAND', 'PHONY')
        elem.add_item('COMMAND', [ninja_command, '-t', 'clean'])
        elem.add_item('description', 'Cleaning')
        if self.environment.coredata.get_builtin_option('coverage'):
            self.generate_gcov_clean(outfile)
            elem.add_dep('clean-gcda')
            elem.add_dep('clean-gcno')
        elem.write(outfile)
        self.check_outputs(elem)

        deps = self.get_regen_filelist()
        elem = NinjaBuildElement('build.ninja', 'REGENERATE_BUILD', deps)
        elem.add_item('pool', 'console')
        elem.write(outfile)

        elem = NinjaBuildElement(deps, 'phony', '')
        elem.write(outfile)
        self.check_outputs(elem)