cxx.py

# MIT License
#
# Copyright The SCons Foundation
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"""Tool-specific initialization for generic Posix C++ compilers.

There normally shouldn't be any need to import this module directly.
It will usually be imported through the generic SCons.Tool.Tool()
selection method.
"""

import os.path
import re

import SCons.Defaults
import SCons.Util
import SCons.Scanner

compilers = ['CC', 'c++']

CXXSuffixes = ['.cpp', '.cc', '.cxx', '.c++', '.C++', '.mm']
if SCons.Util.case_sensitive_suffixes('.c', '.C'):
    CXXSuffixes.append('.C')

def iscplusplus(source) -> bool:
    if not source:
        # Source might be None for unusual cases like SConf.
        return False
    for s in source:
        if s.sources:
            ext = os.path.splitext(str(s.sources[0]))[1]
            if ext in CXXSuffixes:
                return True
    return False

def gen_module_map_file(root, module_map):
    module_map_text = '$$root ' + str(root) + '\n'
    for module, file in module_map.items():
        module_map_text += str(module) + ' ' + str(file) + '\n'
    return module_map_text

#TODO filter out C++ whitespace and comments
module_decl_re = re.compile("(module;)?(.|\n)*export module (.*);")

def module_emitter(target, source, env):
    if("CXXMODULEPATH" in env):
        env["__CXXMODULEINIT__"](env)

        export = module_decl_re.match(source[0].get_text_contents())
        if export:
            modulename = export[3].strip()
            if modulename not in env["CXXMODULEMAP"]:
                env["CXXMODULEMAP"][modulename] = modulename + env["CXXMODULESUFFIX"]
            target.append(env.File("$CXXMODULEPATH/" + env["CXXMODULEMAP"][modulename]))
    return (target, source, env)

def module_emitter_static(target, source, env):
    import SCons.Defaults
    return SCons.Defaults.StaticObjectEmitter(*module_emitter(target, source, env))

def module_emitter_shared(target, source, env):
    import SCons.Defaults
    return SCons.Defaults.SharedObjectEmitter(*module_emitter(target, source, env))

#TODO filter out C++ whitespace and comments
module_import_re = re.compile(r"\s*(?:(?:export)?\s*import\s*(\S*)\s*;)|(?:(export)?\s*module\s*(\S*)\s*;)")


class CxxModuleScanner(SCons.Scanner.Current):
    def scan(self, node, env, path):
        result = self.c_scanner(node, env, path)

        if not env.get("CXXMODULEPATH"):
            return result

        imports = module_import_re.findall(node.get_text_contents())
        for module, export, impl in imports:
            if not module:
                if not export and impl:  # module implementation unit depends on module interface
                    module = impl
                else:
                    continue
            is_header_unit = False
            if(module[0] == "<" or module[0] == '"'):
                module_id_prefix = "@system-header/" if module[0] == "<" else "@header/"
                cmi = module_id_prefix + module[1:-1] + "$CXXMODULESUFFIX"
                is_header_unit = True
            else:
                cmi = env["CXXMODULEMAP"].get(
                    module, module+"$CXXMODULESUFFIX")
            cmi = env.File("$CXXMODULEPATH/" + cmi)

            if(is_header_unit and not cmi.has_builder()):
                source = self.c_scanner.find_include(
                    (module[0], module[1:-1]), node.dir, path)
                if source[0]:
                    source = source[0]
                else:
                    source = env.Value(module[1:-1])
                env.CxxHeaderUnit(
                    cmi, source,
                    CXXCOMOUTPUTSPEC="$CXXSYSTEMHEADERFLAGS" if module[0] == "<" else "$CXXUSERHEADERFLAGS",
                    CPPPATH = [node.dir, "$CPPPATH"] if module[0] == '"' else "$CPPPATH",
                    CXXMODULEIDPREFIX=module_id_prefix
                )
            result.append(cmi)
        return result

    def __init__(self, *args, **kwargs):
        from SCons.Scanner import FindPathDirs
        super().__init__(self.scan, recursive = True, path_function = FindPathDirs("CPPPATH"), *args, **kwargs)
        from SCons.Tool import CScanner
        self.c_scanner = CScanner


header_unit = SCons.Builder.Builder(action="$CXXCOM",
                                    source_scanner=CxxModuleScanner())

def generate(env) -> None:
    """
    Add Builders and construction variables for Visual Age C++ compilers
    to an Environment.
    """
    import SCons.Tool
    import SCons.Tool.cc
    static_obj, shared_obj = SCons.Tool.createObjBuilders(env)
    from SCons.Tool import SourceFileScanner

    for suffix in CXXSuffixes:
        static_obj.add_action(suffix, SCons.Defaults.CXXAction)
        shared_obj.add_action(suffix, SCons.Defaults.ShCXXAction)
        static_obj.add_emitter(suffix, module_emitter_static)
        shared_obj.add_emitter(suffix, module_emitter_shared)
        SourceFileScanner.add_scanner(suffix, CxxModuleScanner())

    env['BUILDERS']['CxxHeaderUnit'] = header_unit

    SCons.Tool.cc.add_common_cc_variables(env)

    if 'CXX' not in env:
        env['CXX']    = env.Detect(compilers) or compilers[0]
    env['CXXFLAGS']   = SCons.Util.CLVar('')
    env['CXXCOMOUTPUTSPEC'] = '-o $TARGET'
    env['CXXCOM']     = '$CXX $CXXCOMOUTPUTSPEC -c ${ CXXMODULEFLAGS if CXXMODULEPATH else "" } $CXXFLAGS $CCFLAGS $_CCCOMCOM $SOURCES'
    env['CXXMODULEMAP'] = {}
    env['SHCXX']      = '$CXX'
    env['SHCXXFLAGS'] = SCons.Util.CLVar('$CXXFLAGS')
    env['SHCXXCOM']   = '$SHCXX -o $TARGET -c ${ CXXMODULEFLAGS if CXXMODULEPATH else "" } $SHCXXFLAGS $SHCCFLAGS $_CCCOMCOM $SOURCES'

    env['CPPDEFPREFIX']  = '-D'
    env['CPPDEFSUFFIX']  = ''
    env['INCPREFIX']  = '-I'
    env['INCSUFFIX']  = ''
    env['SHOBJSUFFIX'] = '.os'
    env['OBJSUFFIX'] = '.o'
    env['STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME'] = 0

    env['CXXFILESUFFIX'] = '.cc'

def exists(env):
    return env.Detect(env.get('CXX', compilers))

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