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#!/usr/bin/python3
import itertools
import math
import re
from .lexer import lexer
from util import Token
def tokenize(text):
lexer.input(text)
return [Token(t.type, t.value, t.lexpos) for t in lexer]
operators = set([
'FROM', 'IMPLIES', 'NOT',
'EQU', 'NEQU', 'EQ', 'NEQ', 'UNIV', 'IS', 'EQA', 'NEQA',
'LT', 'LE', 'GT', 'GE', 'LTL', 'LEL', 'GTL', 'GEL',
'PLUS', 'MINUS', 'STAR', 'DIV', 'IDIV', 'MOD',
'POW', 'SEMI'
])
def stringify(tokens):
def token_str(t):
if t.type in ('PERIOD', 'COMMA'):
return str(t) + ' '
if t.type in operators:
return ' ' + str(t) + ' '
return str(t)
return ''.join(map(token_str, tokens))
# Yield the sequence of rules in [code].
def split(code):
tokens = tokenize(code)
start = 0
for idx, token in enumerate(tokens):
if token.type == 'PERIOD' and idx - start > 1:
yield stringify(tokens[start:idx])
start = idx + 1
# return a list of lines in 'code', and a list of rule indexes
def decompose(code):
lines = []
rules = []
tokens = tokenize(code)
tokens.append(Token('EOF'))
line = []
parens = []
rule_start = 0
for t in tokens:
if t.type == 'SEMI':
if line != []:
lines.append(tuple(line))
line = []
lines.append((t,))
continue
if not parens:
if t.type in ('PERIOD', 'FROM', 'COMMA', 'EOF'):
if line != []:
lines.append(tuple(line))
line = []
if t.type in ('PERIOD', 'EOF') and rule_start < len(lines):
rules.append((rule_start, len(lines)))
rule_start = len(lines)
continue
if t.type in ('LPAREN', 'LBRACKET', 'LBRACE'):
parens.append(t.type)
elif parens:
if t.type == 'RPAREN' and parens[-1] == 'LPAREN':
parens.pop()
elif t.type == 'RBRACKET' and parens[-1] == 'LBRACKET':
parens.pop()
elif t.type == 'RBRACE' and parens[-1] == 'LBRACE':
parens.pop()
line.append(t)
return tuple(lines), tuple(rules)
# pretty-print a list of rules
def compose(lines, rules):
code = ''
for start, end in rules:
for i in range(start, end):
line = lines[i]
if i > start:
code += ' '
code += stringify(line)
if i == end-1:
code += '.\n'
elif i == start:
code += ' :-\n'
else:
if line and line[-1].type != 'SEMI' and lines[i+1][-1].type != 'SEMI':
code += ','
code += '\n'
return code.strip()
# standardize variable names in order of appearance
def rename_vars(tokens, names={}):
# copy names so we don't fuck it up
names = {k: v for k, v in names.items()}
next_id = len(names)
for i in range(len(tokens)):
if tokens[i].type == 'PERIOD':
names.clear()
next_id = 0
elif tokens[i] == Token('VARIABLE', '_'):
tokens[i] = Token('VARIABLE', 'A' + str(next_id))
next_id += 1
elif tokens[i].type == 'VARIABLE':
cur_name = tokens[i].val
if cur_name not in names:
names[cur_name] = next_id
next_id += 1
tokens[i] = Token('VARIABLE', 'A' + str(names[cur_name]))
return names
# transformation = before → after; applied on line which is part of rule
# return mapping from formal vars in before+after to actual vars in rule
# line and rule should of course not be normalized
def map_vars(before, after, line, rule):
mapping = {}
new_index = 0
for i in range(len(before)):
if line[i].type == 'VARIABLE':
formal_name = before[i].val
if line[i].val != '_':
actual_name = line[i].val
else:
actual_name = 'New'+str(new_index)
new_index += 1
mapping[formal_name] = actual_name
remaining_formal = [t.val for t in after if t.type == 'VARIABLE' and t.val not in mapping.keys()]
remaining_actual = [t.val for t in rule if t.type == 'VARIABLE' and t.val != '_' and t.val not in mapping.values()]
while len(remaining_actual) < len(remaining_formal):
remaining_actual.append('New'+str(new_index))
new_index += 1
for i, formal_name in enumerate(remaining_formal):
mapping[formal_name] = remaining_actual[i]
return mapping
# Basic sanity check.
if __name__ == '__main__':
print(compose(*decompose('dup([H|T], [H1|T1]) :- dup(T1, T2). ')))
rule = tokenize('dup([H|T], [H1|T1]) :- dup(T1, T2). ')
line = tokenize('dup([H|T], [H1|T1]) :-')
before = tokenize("dup([A0|A1], [A2|A3])")
after = tokenize("dup([A0|A1], [A5, A4|A3])")
var_names = rename_vars(before)
rename_vars(after, var_names)
mapping = map_vars(before, after, line, rule)
print(mapping)
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