"""SCons.Tool.lex

Tool-specific initialization for lex.

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.

"""

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__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"

import os.path
import sys

import SCons.Action
import SCons.Tool
import SCons.Util
from SCons.Platform.mingw import MINGW_DEFAULT_PATHS
from SCons.Platform.cygwin import CYGWIN_DEFAULT_PATHS
from SCons.Platform.win32 import CHOCO_DEFAULT_PATH

LexAction = SCons.Action.Action("$LEXCOM", "$LEXCOMSTR")

if sys.platform == 'win32':
    BINS = ['flex', 'lex', 'win_flex']
else:
    BINS = ["flex", "lex"]

def lexEmitter(target, source, env):
    sourceBase, sourceExt = os.path.splitext(SCons.Util.to_String(source[0]))

    if sourceExt == ".lm":           # If using Objective-C
        target = [sourceBase + ".m"] # the extension is ".m".

    # This emitter essentially tries to add to the target all extra
    # files generated by flex.

    # Different options that are used to trigger the creation of extra files.
    fileGenOptions = ["--header-file=", "--tables-file="]

    lexflags = env.subst("$LEXFLAGS", target=target, source=source)
    for option in SCons.Util.CLVar(lexflags):
        for fileGenOption in fileGenOptions:
            l = len(fileGenOption)
            if option[:l] == fileGenOption:
                # A file generating option is present, so add the
                # file name to the target list.
                fileName = option[l:].strip()
                target.append(fileName)
    return (target, source)

def get_lex_path(env, append_paths=False):
    """
    Find the path to the lex tool, searching several possible names

    Only called in the Windows case, so the default_path
    can be Windows-specific

    :param env: current construction environment
    :param append_paths: if set, add the path to the tool to PATH
    :return: path to lex tool, if found
    """
    for prog in BINS:
        bin_path = SCons.Tool.find_program_path(
            env,
            prog,
            default_paths=CHOCO_DEFAULT_PATH + MINGW_DEFAULT_PATHS + CYGWIN_DEFAULT_PATHS )
        if bin_path:
            if append_paths:
                env.AppendENVPath('PATH', os.path.dirname(bin_path))
            return bin_path
    SCons.Warnings.SConsWarning('lex tool requested, but lex or flex binary not found in ENV PATH')


def generate(env):
    """Add Builders and construction variables for lex to an Environment."""
    c_file, cxx_file = SCons.Tool.createCFileBuilders(env)

    # C
    c_file.add_action(".l", LexAction)
    c_file.add_emitter(".l", lexEmitter)

    c_file.add_action(".lex", LexAction)
    c_file.add_emitter(".lex", lexEmitter)

    # Objective-C
    cxx_file.add_action(".lm", LexAction)
    cxx_file.add_emitter(".lm", lexEmitter)

    # C++
    cxx_file.add_action(".ll", LexAction)
    cxx_file.add_emitter(".ll", lexEmitter)

    env["LEXFLAGS"] = SCons.Util.CLVar("")

    if sys.platform == 'win32':
        # ignore the return - we do not need the full path here
        _ = get_lex_path(env, append_paths=True)
        env["LEX"] = env.Detect(BINS)
        if not env.get("LEXUNISTD"):
            env["LEXUNISTD"] = SCons.Util.CLVar("")
        env["LEXCOM"] = "$LEX $LEXUNISTD $LEXFLAGS -t $SOURCES > $TARGET"
    else:
        env["LEX"] = env.Detect(BINS)
        env["LEXCOM"] = "$LEX $LEXFLAGS -t $SOURCES > $TARGET"

def exists(env):
    if sys.platform == 'win32':
        return get_lex_path(env)
    else:
        return env.Detect(BINS)

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