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allendowney
GitHub Repository: allendowney/cpython
 Path: blob/main/Tools/build/generate_sre_constants.py
12 views
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#! /usr/bin/env python3

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# This script generates Modules/_sre/sre_constants.h from Lib/re/_constants.py.

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SCRIPT_NAME = 'Tools/build/generate_sre_constants.py'

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def update_file(file, content):

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    try:

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        with open(file, 'r') as fobj:

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            if fobj.read() == content:

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                return False

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    except (OSError, ValueError):

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        pass

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    with open(file, 'w') as fobj:

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        fobj.write(content)

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    return True

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sre_constants_header = f"""\

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/*

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 * Secret Labs' Regular Expression Engine

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 *

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 * regular expression matching engine

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 *

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 * Auto-generated by {SCRIPT_NAME} from

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 * Lib/re/_constants.py.

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 *

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 * Copyright (c) 1997-2001 by Secret Labs AB.  All rights reserved.

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 *

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 * See the sre.c file for information on usage and redistribution.

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 */

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"""

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def main(

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    infile="Lib/re/_constants.py",

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    outfile_constants="Modules/_sre/sre_constants.h",

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    outfile_targets="Modules/_sre/sre_targets.h",

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):

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    ns = {}

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    with open(infile) as fp:

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        code = fp.read()

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    exec(code, ns)

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    def dump(d, prefix):

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        items = sorted(d)

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        for item in items:

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            yield "#define %s_%s %d\n" % (prefix, item, item)

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    def dump2(d, prefix):

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        items = [(value, name) for name, value in d.items()

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                 if name.startswith(prefix)]

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        for value, name in sorted(items):

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            yield "#define %s %d\n" % (name, value)

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    def dump_gotos(d, prefix):

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        for i, item in enumerate(sorted(d)):

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            assert i == item

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            yield f"    &&{prefix}_{item},\n"

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    content = [sre_constants_header]

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    content.append("#define SRE_MAGIC %d\n" % ns["MAGIC"])

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    content.extend(dump(ns["OPCODES"], "SRE_OP"))

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    content.extend(dump(ns["ATCODES"], "SRE"))

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    content.extend(dump(ns["CHCODES"], "SRE"))

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    content.extend(dump2(ns, "SRE_FLAG_"))

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    content.extend(dump2(ns, "SRE_INFO_"))

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    update_file(outfile_constants, ''.join(content))

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    content = [sre_constants_header]

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    content.append(f"static void *sre_targets[{len(ns['OPCODES'])}] = {{\n")

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    content.extend(dump_gotos(ns["OPCODES"], "TARGET_SRE_OP"))

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    content.append("};\n")

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    update_file(outfile_targets, ''.join(content))

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if __name__ == '__main__':

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    import sys

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    main(*sys.argv[1:])

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