def token(self, name, value, source):
#print "tok:", name, "->", source.debug()
#print "Token", name, value
if name == "SYMDEF":
return value
elif name == "STRING":
tok = self.tokens.get(value)
if not tok:
tok = Token(value)
self.tokens[value] = tok
return tok
elif name == "SYMBOL":
sym = self.terminals.get(value)
if not sym:
sym = Token(value)
self.terminals[value] = sym
return sym
elif name in (
'*',
'+',
'(',
'[',
']',
')',
'|',
):
return name
return BuilderToken(name, value)
def grammar_grammar():
"""Builds the grammar for the grammar file
"""
# star: '*' | '+'
star = Alternative("star", Token('*'), Token('+'))
star_opt = KleeneStar("star_opt", 0, 1, rule=star)
# rule: SYMBOL ':' alternative
symbol = Sequence("symbol", Token('SYMBOL'), star_opt)
symboldef = Token("SYMDEF")
alternative = Sequence("alternative")
rule = Sequence("rule", symboldef, alternative)
# grammar: rule+
grammar = KleeneStar("grammar", _min=1, rule=rule)
# alternative: sequence ( '|' sequence )*
sequence = KleeneStar("sequence", 1)
seq_cont_list = Sequence("seq_cont_list", Token('|'), sequence)
sequence_cont = KleeneStar("sequence_cont", 0, rule=seq_cont_list)
alternative.args = [sequence, sequence_cont]
# option: '[' alternative ']'
option = Sequence("option", Token('['), alternative, Token(']'))
# group: '(' alternative ')'
group = Sequence("group", Token('('), alternative, Token(')'), star_opt)
# sequence: (SYMBOL | STRING | option | group )+
string = Token('STRING')
alt = Alternative("sequence_alt", symbol, string, option, group)
sequence.args = [alt]
return grammar
def visit_STRING(self, node):
value = node.value
tok = self.tokens.get(value)
if not tok:
if pylexer.py_punct.match(value):
tok = Token(value)
elif pylexer.py_name.match(value):
tok = Token('NAME', value)
else:
raise SyntaxError("Unknown STRING value ('%s')" % value)
self.tokens[value] = tok
return tok
def handle_TOK_STRING( self, name, value ):
if value in self.parser.tok_values:
# punctuation
tokencode = self.parser.tok_values[value]
tok = Token(self.parser, tokencode, None)
else:
if not is_py_name(value):
raise RuntimeError("Unknown STRING value ('%s')" % value)
# assume a keyword
tok = Token(self.parser, self.parser.tokens['NAME'], value)
if value not in self.keywords:
self.keywords.append(value)
self.rule_stack.append(tok)
def next(self):
"""returns the next token"""
# We only support 1-lookahead which
# means backtracking more than one token
# will re-tokenize the stream (but this is the
# grammar lexer so we don't care really!)
_p = self.parser
if self._peeked is not None:
peeked = self._peeked
self._peeked = None
return peeked
pos = self.pos
inp = self.input
end = len(self.input)
pos = self.skip_empty_lines(inp, pos, end)
if pos == end:
return Token(_p, _p.EOF, None)
# at this point nextchar is not a white space nor \n
nextchr = inp[pos]
if nextchr == "'":
npos = self.match_string(inp, pos, end)
# could get a string terminated by EOF here
if npos == end and inp[end - 1] != "'":
self.RaiseError("Unterminated string")
self.pos = npos
_endpos = npos - 1
assert _endpos >= 0
return Token(_p, _p.TOK_STRING, inp[pos + 1:_endpos])
else:
npos = match_symbol(inp, pos, end)
if npos != pos:
self.pos = npos
if npos != end and inp[npos] == ":":
self.pos += 1
return Token(_p, _p.TOK_SYMDEF, inp[pos:npos])
else:
return Token(_p, _p.TOK_SYMBOL, inp[pos:npos])
# we still have pos!=end here
chr = inp[pos]
if chr in "[]()*+|":
self.pos = pos + 1
return Token(_p, _p.tok_values[chr], chr)
self.RaiseError("Unknown token")
def visit_symbol(self, node):
star_opt = node.nodes[1]
sym = node.nodes[0].value
terminal = self.terminals.get(sym)
if not terminal:
terminal = Token(sym)
self.terminals[sym] = terminal
return self.repeat(star_opt, terminal)
n_dev = int(n * 0.1)
n_test = int(n * 0.1)
train_data = data[:n_train]
dev_data = data[n_train:n_train + n_dev]
test_data = data[n_train + n_dev:]
# train_data = train_data[:100]
print('done')
print(
f'-> {n} sentences loaded ({n_train} train, {n_dev} dev, {n_test} test)'
)
# create PCFG
print('Computing PCFG from training corpus...', end='', flush=True)
grammar = PCFG(train_data, Token('SENT'))
print('done')
# transform PCFG so that it is in Chomsky normal form
print('Converting PCFG to Chomsky normal form...', end='', flush=True)
grammar.chomsky_normal_form()
print('done')
# compute grammar stats
print('Retrieving grammar symbols and productions...', end='', flush=True)
grammar.compute_symbols()
grammar.compute_productions()
print('done')
print(
f'-> {grammar.n_all_symbols} non-terminal symbols ({grammar.n_corpus_symbols} originals, '
f'{grammar.n_artificial_symbols} artificials), {grammar.n_terminals} terminal words'
def test1():
# Test grammar 1
print("------ Test 1 ---------")
# Abbreviations
NT = Nonterminal
TERM = Terminal
# Hard-coded test case - grammar not read from file
E = NT('E')
T = NT('T')
P = NT('P')
plus = TERM('+')
mult = TERM('*')
ident = TERM('ident')
g = {
E: [Production(rhs=[E, plus, T]),
Production(rhs=[T])],
T: [Production(rhs=[T, mult, P]),
Production(rhs=[P])],
P: [Production(rhs=[ident])],
}
p = Parser(g, E)
s = [
Token('ident', 'a'),
Token('*', '*'),
Token('ident', 'b'),
Token('+', '+'),
Token('ident', 'c'),
Token('*', '*'),
Token('ident', 'd'),
Token('+', '+'),
Token('ident', 'e'),
Token('+', '+'),
Token('ident', 'f')
]
forest = p.go(s)
print("Parse combinations: {0}".format(Parser.num_combinations(forest)))
ParseForestPrinter.print_forest(forest)
def make_token(w):
if w[0].isupper():
return NameToken('nafn', w)
return Token('orð', w)
def get_token(self, codename ):
"""Returns a new or existing Token"""
if codename in self.tokens:
return self.tokens[codename]
token = self.tokens[codename] = Token(self.parser, codename, None)
return token
