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comparison ply-3.8/test/yacc_error5.py @ 7267:343ff337a19b

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<ais523> ` tar -xf ply-3.8.tar.gz
author HackBot
date Wed, 23 Mar 2016 02:40:16 +0000
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7266:61a39a120dee 7267:343ff337a19b
1 # -----------------------------------------------------------------------------
2 # yacc_error5.py
3 #
4 # Lineno and position tracking with error tokens
5 # -----------------------------------------------------------------------------
6 import sys
7
8 if ".." not in sys.path: sys.path.insert(0,"..")
9 import ply.yacc as yacc
10
11 from calclex import tokens
12
13 # Parsing rules
14 precedence = (
15 ('left','PLUS','MINUS'),
16 ('left','TIMES','DIVIDE'),
17 ('right','UMINUS'),
18 )
19
20 # dictionary of names
21 names = { }
22
23 def p_statement_assign(t):
24 'statement : NAME EQUALS expression'
25 names[t[1]] = t[3]
26
27 def p_statement_assign_error(t):
28 'statement : NAME EQUALS error'
29 line_start, line_end = t.linespan(3)
30 pos_start, pos_end = t.lexspan(3)
31 print("Assignment Error at %d:%d to %d:%d" % (line_start,pos_start,line_end,pos_end))
32
33 def p_statement_expr(t):
34 'statement : expression'
35 print(t[1])
36
37 def p_expression_binop(t):
38 '''expression : expression PLUS expression
39 | expression MINUS expression
40 | expression TIMES expression
41 | expression DIVIDE expression'''
42 if t[2] == '+' : t[0] = t[1] + t[3]
43 elif t[2] == '-': t[0] = t[1] - t[3]
44 elif t[2] == '*': t[0] = t[1] * t[3]
45 elif t[2] == '/': t[0] = t[1] / t[3]
46
47 def p_expression_uminus(t):
48 'expression : MINUS expression %prec UMINUS'
49 t[0] = -t[2]
50
51 def p_expression_group(t):
52 'expression : LPAREN expression RPAREN'
53 line_start, line_end = t.linespan(2)
54 pos_start, pos_end = t.lexspan(2)
55 print("Group at %d:%d to %d:%d" % (line_start,pos_start, line_end, pos_end))
56 t[0] = t[2]
57
58 def p_expression_group_error(t):
59 'expression : LPAREN error RPAREN'
60 line_start, line_end = t.linespan(2)
61 pos_start, pos_end = t.lexspan(2)
62 print("Syntax error at %d:%d to %d:%d" % (line_start,pos_start, line_end, pos_end))
63 t[0] = 0
64
65 def p_expression_number(t):
66 'expression : NUMBER'
67 t[0] = t[1]
68
69 def p_expression_name(t):
70 'expression : NAME'
71 try:
72 t[0] = names[t[1]]
73 except LookupError:
74 print("Undefined name '%s'" % t[1])
75 t[0] = 0
76
77 def p_error(t):
78 print("Syntax error at '%s'" % t.value)
79
80 parser = yacc.yacc()
81 import calclex
82 calclex.lexer.lineno=1
83 parser.parse("""
84 a = 3 +
85 (4*5) +
86 (a b c) +
87 + 6 + 7
88 """, tracking=True)
89
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