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1# ply: ygen.py
2#
3# This is a support program that auto-generates different versions of the YACC parsing
4# function with different features removed for the purposes of performance.
5#
6# Users should edit the method LParser.parsedebug() in yacc.py.   The source code
7# for that method is then used to create the other methods.   See the comments in
8# yacc.py for further details.
9
10import os.path
11import shutil
12
13def get_source_range(lines, tag):
14    srclines = enumerate(lines)
15    start_tag = '#--! %s-start' % tag
16    end_tag = '#--! %s-end' % tag
17
18    for start_index, line in srclines:
19        if line.strip().startswith(start_tag):
20            break
21
22    for end_index, line in srclines:
23        if line.strip().endswith(end_tag):
24            break
25
26    return (start_index + 1, end_index)
27
28def filter_section(lines, tag):
29    filtered_lines = []
30    include = True
31    tag_text = '#--! %s' % tag
32    for line in lines:
33        if line.strip().startswith(tag_text):
34            include = not include
35        elif include:
36            filtered_lines.append(line)
37    return filtered_lines
38
39def main():
40    dirname = os.path.dirname(__file__)
41    shutil.copy2(os.path.join(dirname, 'yacc.py'), os.path.join(dirname, 'yacc.py.bak'))
42    with open(os.path.join(dirname, 'yacc.py'), 'r') as f:
43        lines = f.readlines()
44
45    parse_start, parse_end = get_source_range(lines, 'parsedebug')
46    parseopt_start, parseopt_end = get_source_range(lines, 'parseopt')
47    parseopt_notrack_start, parseopt_notrack_end = get_source_range(lines, 'parseopt-notrack')
48
49    # Get the original source
50    orig_lines = lines[parse_start:parse_end]
51
52    # Filter the DEBUG sections out
53    parseopt_lines = filter_section(orig_lines, 'DEBUG')
54
55    # Filter the TRACKING sections out
56    parseopt_notrack_lines = filter_section(parseopt_lines, 'TRACKING')
57
58    # Replace the parser source sections with updated versions
59    lines[parseopt_notrack_start:parseopt_notrack_end] = parseopt_notrack_lines
60    lines[parseopt_start:parseopt_end] = parseopt_lines
61
62    lines = [line.rstrip()+'\n' for line in lines]
63    with open(os.path.join(dirname, 'yacc.py'), 'w') as f:
64        f.writelines(lines)
65
66    print('Updated yacc.py')
67
68if __name__ == '__main__':
69    main()
70
71
72
73
74
75