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gta3script-specs/tools/asciidoctor-grammar-preproc...

69 lines
2.3 KiB
Python

#!/usr/bin/env python3
"""
This script preprocesses an Asciidoc document, gathering all grammar
productions and dumping it into a `AUTO_REPLACE_WITH_GRAMMAR` section.
"""
import sys
class GrammarPreprocessor:
def __init__(self, reader, writer):
self.reader = reader
self.writer = writer
@staticmethod
def emit_error(block, error):
print('invalid grammar block: ' + error, file=sys.stderr)
print(block, file=sys.stderr)
sys.exit(1)
@staticmethod
def is_grammar_block(block):
first_line = block.split('\n', 1)[0]
if first_line.startswith('#') and 'informative' in first_line:
return False
return ':=' in block
def validate_grammar(self, block):
expect_semicolon = False
for i in range(len(block)):
if block[i] == ':' and i+1 != len(block) and block[i+1] == '=':
if expect_semicolon:
return self.emit_error(block, 'missing semicolon')
expect_semicolon = True
if block[i] == ';':
if not expect_semicolon:
return self.emit_error(block, 'unexpected semicolon')
expect_semicolon = False
if expect_semicolon:
return self.emit_error(block, 'missing semicolon')
def read_block(self):
lines = []
for line in self.reader:
self.writer.write(line)
if line.startswith('---'):
break
lines.append(line)
return ''.join(lines)
def process(self):
grammar = []
for line in self.reader:
if line.startswith('AUTO_REPLACE_WITH_GRAMMAR'):
self.writer.write('----\n')
self.writer.write('# The GTA3script Grammar (informative)\n\n')
self.writer.write('\n'.join(grammar))
self.writer.write('----\n')
continue
self.writer.write(line)
if line.startswith('---'):
block = self.read_block()
if self.is_grammar_block(block):
self.validate_grammar(block)
grammar.append(block)
if __name__ == '__main__':
pp = GrammarPreprocessor(sys.stdin, sys.stdout)
pp.process()