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Improved error checking and messages

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This commit is contained in:
David Beazley 2018-11-16 14:50:33 -06:00
parent 16d700b310
commit 0ac3c1a0a3
1 changed files with 18 additions and 22 deletions
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40
sly/yacc.py
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@ -103,6 +103,7 @@ class YaccSymbol:
# ---------------------------------------------------------------------- # ----------------------------------------------------------------------
class YaccProduction: class YaccProduction:
__slots__ = ('_slice', '_namemap', '_stack')
def __init__(self, s, stack=None): def __init__(self, s, stack=None):
self._slice = s self._slice = s
self._namemap = { } self._namemap = { }
@ -147,7 +148,8 @@ class YaccProduction:
if name in self._namemap: if name in self._namemap:
return self._slice[self._namemap[name]].value return self._slice[self._namemap[name]].value
else: else:
raise AttributeError(f'No symbol {name}') nameset = '{' + ', '.join(self._namemap) + '}'
raise AttributeError(f'No symbol {name}. Must be one of {nameset}.')
def __setattr__(self, name, value): def __setattr__(self, name, value):
if name[0:1] == '_' or name not in self._namemap: if name[0:1] == '_' or name not in self._namemap:
@ -389,7 +391,7 @@ class Grammar(object):
if term in self.Precedence: if term in self.Precedence:
raise GrammarError(f'Precedence already specified for terminal {term!r}') raise GrammarError(f'Precedence already specified for terminal {term!r}')
if assoc not in ['left', 'right', 'nonassoc']: if assoc not in ['left', 'right', 'nonassoc']:
raise GrammarError("Associativity must be one of 'left','right', or 'nonassoc'") raise GrammarError(f"Associativity of {term!r} must be one of 'left','right', or 'nonassoc'")
self.Precedence[term] = (assoc, level) self.Precedence[term] = (assoc, level)
# ----------------------------------------------------------------------------- # -----------------------------------------------------------------------------
@ -1562,6 +1564,8 @@ class ParserMetaDict(dict):
def __setitem__(self, key, value): def __setitem__(self, key, value):
if key in self and callable(value) and hasattr(value, 'rules'): if key in self and callable(value) and hasattr(value, 'rules'):
value.next_func = self[key] value.next_func = self[key]
if not hasattr(value.next_func, 'rules'):
raise GrammarError(f'Redefinition of {key}. Perhaps an earlier {key} is missing @_')
super().__setitem__(key, value) super().__setitem__(key, value)
def __getitem__(self, key): def __getitem__(self, key):
@ -1659,11 +1663,10 @@ class Parser(metaclass=ParserMeta):
Build the grammar from the grammar rules Build the grammar from the grammar rules
''' '''
grammar_rules = [] grammar_rules = []
fail = False errors = ''
# Check for non-empty symbols # Check for non-empty symbols
if not rules: if not rules:
cls.log.error('no grammar rules are defined') raise YaccError('No grammar rules are defined')
return False
grammar = Grammar(cls.tokens) grammar = Grammar(cls.tokens)
@ -1672,8 +1675,7 @@ class Parser(metaclass=ParserMeta):
try: try:
grammar.set_precedence(term, assoc, level) grammar.set_precedence(term, assoc, level)
except GrammarError as e: except GrammarError as e:
cls.log.error(str(e)) errors += f'{e}\n'
fail = True
for name, func in rules: for name, func in rules:
try: try:
@ -1682,21 +1684,17 @@ class Parser(metaclass=ParserMeta):
try: try:
grammar.add_production(prodname, syms, pfunc, rulefile, ruleline) grammar.add_production(prodname, syms, pfunc, rulefile, ruleline)
except GrammarError as e: except GrammarError as e:
cls.log.error(str(e)) errors += f'{e}\n'
fail = True
except SyntaxError as e: except SyntaxError as e:
cls.log.error(str(e)) errors += f'{e}\n'
fail = True
try: try:
grammar.set_start(getattr(cls, 'start', None)) grammar.set_start(getattr(cls, 'start', None))
except GrammarError as e: except GrammarError as e:
cls.log.error(str(e)) errors += f'{e}\n'
fail = True
undefined_symbols = grammar.undefined_symbols() undefined_symbols = grammar.undefined_symbols()
for sym, prod in undefined_symbols: for sym, prod in undefined_symbols:
cls.log.error(f'%s:%d: Symbol %r used, but not defined as a token or a rule', prod.file, prod.line, sym) errors += '%s:%d: Symbol %r used, but not defined as a token or a rule\n' % (prod.file, prod.line, sym)
fail = True
unused_terminals = grammar.unused_terminals() unused_terminals = grammar.unused_terminals()
if unused_terminals: if unused_terminals:
@ -1723,16 +1721,15 @@ class Parser(metaclass=ParserMeta):
infinite = grammar.infinite_cycles() infinite = grammar.infinite_cycles()
for inf in infinite: for inf in infinite:
cls.log.error('Infinite recursion detected for symbol %r', inf) errors += 'Infinite recursion detected for symbol %r\n' % inf
fail = True
unused_prec = grammar.unused_precedence() unused_prec = grammar.unused_precedence()
for term, assoc in unused_prec: for term, assoc in unused_prec:
cls.log.error('Precedence rule %r defined for unknown symbol %r', assoc, term) errors += 'Precedence rule %r defined for unknown symbol %r\n' % (assoc, term)
fail = True
cls._grammar = grammar cls._grammar = grammar
return not fail if errors:
raise YaccError('Unable to build grammar.\n'+errors)
@classmethod @classmethod
def __build_lrtables(cls): def __build_lrtables(cls):
@ -1786,8 +1783,7 @@ class Parser(metaclass=ParserMeta):
raise YaccError('Invalid parser specification') raise YaccError('Invalid parser specification')
# Build the underlying grammar object # Build the underlying grammar object
if not cls.__build_grammar(rules): cls.__build_grammar(rules)
raise YaccError('Invalid grammar')
# Build the LR tables # Build the LR tables
if not cls.__build_lrtables(): if not cls.__build_lrtables():