# ply: ygen.py
#
# This is a support program that auto-generates different versions of the YACC parsing
# function with different features removed for the purposes of performance.
#
# Users should edit the method LParser.parsedebug() in yacc.py. The source code
# for that method is then used to create the other methods. See the comments in
# yacc.py for further details.
import os.path
import shutil
[docs]def get_source_range(lines, tag):
srclines = enumerate(lines)
start_tag = '#--! %s-start' % tag
end_tag = '#--! %s-end' % tag
for start_index, line in srclines:
if line.strip().startswith(start_tag):
break
for end_index, line in srclines:
if line.strip().endswith(end_tag):
break
return (start_index + 1, end_index)
[docs]def filter_section(lines, tag):
filtered_lines = []
include = True
tag_text = '#--! %s' % tag
for line in lines:
if line.strip().startswith(tag_text):
include = not include
elif include:
filtered_lines.append(line)
return filtered_lines
[docs]def main():
dirname = os.path.dirname(__file__)
shutil.copy2(os.path.join(dirname, 'yacc.py'), os.path.join(dirname, 'yacc.py.bak'))
with open(os.path.join(dirname, 'yacc.py'), 'r') as f:
lines = f.readlines()
parse_start, parse_end = get_source_range(lines, 'parsedebug')
parseopt_start, parseopt_end = get_source_range(lines, 'parseopt')
parseopt_notrack_start, parseopt_notrack_end = get_source_range(lines, 'parseopt-notrack')
# Get the original source
orig_lines = lines[parse_start:parse_end]
# Filter the DEBUG sections out
parseopt_lines = filter_section(orig_lines, 'DEBUG')
# Filter the TRACKING sections out
parseopt_notrack_lines = filter_section(parseopt_lines, 'TRACKING')
# Replace the parser source sections with updated versions
lines[parseopt_notrack_start:parseopt_notrack_end] = parseopt_notrack_lines
lines[parseopt_start:parseopt_end] = parseopt_lines
lines = [line.rstrip()+'\n' for line in lines]
with open(os.path.join(dirname, 'yacc.py'), 'w') as f:
f.writelines(lines)
print('Updated yacc.py')
if __name__ == '__main__':
main()