import ast, _ast, sys, collections
sys.path.append('..')
from runac import parser
TITLE = 'Language grammar'
PARSER_FILE = '../runac/parser.py'
INTRO = '''The table below (which is generated from the parser's source code)
can serve as a guide to Runa's grammar.
Code literals in rules represent regular expressions.
The special INDENT and DEDENT tokens are inserted by a secondary pass,
after the initial tokenization of source code;
they represent the increase and decrease of the indentation level.'''
def get_rules():
with open(PARSER_FILE) as f:
src = f.read()
rules = collections.OrderedDict()
for node in ast.parse(src).body:
if not isinstance(node, _ast.FunctionDef):
continue
if not node.decorator_list:
continue
assert len(node.decorator_list) == 1
decorator = node.decorator_list[0]
if not isinstance(decorator, _ast.Call):
continue
func = decorator.func
if not isinstance(func, _ast.Attribute):
continue
assert func.attr == 'production'
ln = decorator.args[0].s
name, match = ln.split(' : ', 1)
rules.setdefault(name, []).append(tuple(match.split()))
return rules
def get_tokens():
tokens = {'INDENT': 'INDENT', 'DEDENT': 'DEDENT'}
for rule in parser.LEXER.rules:
name, pattern = rule.name, rule.re.pattern
tokens[rule.name] = rule.re.pattern
for word in parser.NAME_LIKE:
tokens[word.upper()] = word
return tokens
def main():
rules, tokens = get_rules(), get_tokens()
lines, columns = [], [0, 0]
for name, expands in rules.iteritems():
columns[0] = max(columns[0], len(name))
for i, expand in enumerate(expands):
bits = list(expand)
for idx, s in enumerate(expand):
if s.upper() == s:
bits[idx] = '``' + tokens[s] + '``'
defn = ' '.join(bits)
columns[1] = max(columns[1], len(defn))
lines.append((name if not i else '', defn))
separator = ''.join((
'+',
'-' * (columns[0] + 2),
'+',
'-' * (columns[1] + 2),
'+',
))
fmt = '| %%-%is | %%-%is |' % tuple(columns)
print '*' * len(TITLE)
print TITLE
print '*' * len(TITLE)
print
print INTRO
print
for i, ln in enumerate(lines):
print separator
print fmt % ln
print separator
if __name__ == '__main__':
main()
