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# CodeQ: an online programming tutor.
# Copyright (C) 2015 UL FRI
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from nltk import Tree
import ply.yacc as yacc
from .lexer import tokens
from .util import Token
# PARSER
precedence = (
('nonassoc', 'FROM'),
('right', 'IMPLIES'),
('right', 'NOT'),
('nonassoc', 'EQU', 'NEQU', 'EQ', 'NEQ', 'UNIV', 'IS', 'EQA', 'NEQA', 'LT', 'LE', 'GT', 'GE', 'LTL', 'LEL', 'GTL', 'GEL'),
('left', 'PLUS', 'MINUS'),
('left', 'STAR', 'DIV', 'IDIV', 'MOD'),
('nonassoc', 'POW'),
('right', 'UMINUS', 'UPLUS'),
('nonassoc', 'UINTEGER', 'UREAL'),
('nonassoc', 'NAME', 'VARIABLE', 'STRING'),
('nonassoc', 'PERIOD'),
('nonassoc', 'LBRACKET', 'RBRACKET', 'LPAREN', 'RPAREN', 'COMMA', 'SEMI', 'PIPE', 'LBRACE', 'RBRACE')
)
def make_token(p, n):
lextoken = p.slice[n]
return Token(lextoken.type, lextoken.value, lextoken.lexpos)
def p_text_empty(p):
'text : '
p[0] = Tree('text', [])
def p_text_clause(p):
'text : text clause'
p[0] = p[1]
p[0].append(p[2])
def p_clause_head(p):
'clause : head PERIOD'
p[0] = Tree('clause', [p[1], make_token(p, 2)])
def p_clause_rule(p):
'clause : head FROM or PERIOD'
p[0] = Tree('clause', [p[1], make_token(p, 2), p[3], make_token(p, 4)])
def p_head(p):
'head : term'
p[0] = Tree('head', [p[1]])
def p_or_single(p):
'or : if'
p[0] = p[1]
def p_or_if(p):
'or : or SEMI if'
if p[1].label() == 'or':
p[0] = p[1]
else:
p[0] = Tree('or', [p[1]])
p[0].append(make_token(p, 2))
p[0].append(p[3])
def p_if_single(p):
'if : and'
p[0] = p[1]
def p_if_and(p):
'if : and IMPLIES if'
p[0] = Tree('if', [p[1], make_token(p, 2), p[3]])
def p_and_single(p):
'and : term'
p[0] = p[1]
def p_and_term(p):
'and : and COMMA term'
if p[1].label() == 'and':
p[0] = p[1]
else:
p[0] = Tree('and', [p[1]])
p[0].append(make_token(p, 2))
p[0].append(p[3])
# Special case for zero-arity predicates supported by SWI-Prolog.
def p_term_functor_zero(p):
'term : functor LPAREN RPAREN'
# No whitespace allowed between functor and LPAREN.
t2 = make_token(p, 2)
if p[1][0].pos + len(p[1][0].val) < t2.pos:
raise SyntaxError('whitespace before ' + str(t2))
p[0] = Tree('term', [p[1], t2, make_token(p, 3)])
def p_term_functor(p):
'term : functor LPAREN args RPAREN'
# No whitespace allowed between functor and LPAREN.
t2 = make_token(p, 2)
if p[1][0].pos + len(p[1][0].val) < t2.pos:
raise SyntaxError('whitespace before ' + str(t2))
p[0] = Tree('term', [p[1], t2, p[3], make_token(p, 4)])
def p_term_or(p):
'term : LPAREN or RPAREN'
p[0] = Tree('term', [make_token(p, 1), p[2], make_token(p, 3)])
def p_term_binary(p):
'''term : term PLUS term
| term MINUS term
| term STAR term
| term POW term
| term DIV term
| term IDIV term
| term MOD term
| term EQU term
| term NEQU term
| term EQ term
| term NEQ term
| term UNIV term
| term IS term
| term EQA term
| term NEQA term
| term LT term
| term LE term
| term GT term
| term GE term
| term LTL term
| term LEL term
| term GTL term
| term GEL term'''
p[0] = Tree('term', [p[1], make_token(p, 2), p[3]])
def p_term_unary(p):
'''term : NOT term
| MINUS term %prec UMINUS
| PLUS term %prec UPLUS'''
p[0] = Tree('term', [make_token(p, 1), p[2]])
def p_term_list(p):
'term : list'
p[0] = Tree('term', [p[1]])
def p_term_simple(p):
'''term : STRING
| NAME
| UINTEGER
| UREAL
| VARIABLE'''
p[0] = Tree('term', [make_token(p, 1)])
def p_args_single(p):
'args : term'
p[0] = Tree('args', [p[1]])
def p_args_term(p):
'args : args COMMA term'
p[0] = p[1]
p[0].append(make_token(p, 2))
p[0].append(p[3])
def p_list_empty(p):
'list : LBRACKET RBRACKET'
p[0] = Tree('list', [make_token(p, 1), make_token(p, 2)])
def p_list(p):
'list : LBRACKET args RBRACKET'
p[0] = Tree('list', [make_token(p, 1)] + list(p[2]) + [make_token(p, 3)])
def p_list_tail(p):
'list : LBRACKET args PIPE term RBRACKET'
p[0] = Tree('list', [make_token(p, 1)] + list(p[2]) + [make_token(p, 3), p[4], make_token(p, 5)])
def p_functor(p):
'functor : NAME'
p[0] = Tree('functor', [make_token(p, 1)])
def p_error(t):
if t is None:
raise SyntaxError('unexpected end of file')
else:
raise SyntaxError('{}: unexpected {}'.format(t.lexpos, t.value))
parser = yacc.yacc(debug=False)
if __name__ == '__main__':
from .util import stringify
while True:
try:
s = input('> ')
except EOFError:
break
if not s:
continue
ast = parser.parse(s)
print(stringify(ast))
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