1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
# Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""This module defines the data structures used to represent a grammar.
These are a bit arcane because they are derived from the data
structures used by Python's 'pgen' parser generator.
There's also a table here mapping operators to their names in the
token module; the Python tokenize module reports all operators as the
fallback token code OP, but the parser needs the actual token code.
"""
# Python imports
import pickle
# Local imports
from . import token, tokenize
class Grammar(object):
"""Pgen parsing tables conversion class.
Once initialized, this class supplies the grammar tables for the
parsing engine implemented by parse.py. The parsing engine
accesses the instance variables directly. The class here does not
provide initialization of the tables; several subclasses exist to
do this (see the conv and pgen modules).
The load() method reads the tables from a pickle file, which is
much faster than the other ways offered by subclasses. The pickle
file is written by calling dump() (after loading the grammar
tables using a subclass). The report() method prints a readable
representation of the tables to stdout, for debugging.
The instance variables are as follows:
symbol2number -- a dict mapping symbol names to numbers. Symbol
numbers are always 256 or higher, to distinguish
them from token numbers, which are between 0 and
255 (inclusive).
number2symbol -- a dict mapping numbers to symbol names;
these two are each other's inverse.
states -- a list of DFAs, where each DFA is a list of
states, each state is a list of arcs, and each
arc is a (i, j) pair where i is a label and j is
a state number. The DFA number is the index into
this list. (This name is slightly confusing.)
Final states are represented by a special arc of
the form (0, j) where j is its own state number.
dfas -- a dict mapping symbol numbers to (DFA, first)
pairs, where DFA is an item from the states list
above, and first is a set of tokens that can
begin this grammar rule (represented by a dict
whose values are always 1).
labels -- a list of (x, y) pairs where x is either a token
number or a symbol number, and y is either None
or a string; the strings are keywords. The label
number is the index in this list; label numbers
are used to mark state transitions (arcs) in the
DFAs.
start -- the number of the grammar's start symbol.
keywords -- a dict mapping keyword strings to arc labels.
tokens -- a dict mapping token numbers to arc labels.
"""
def __init__(self):
self.symbol2number = {}
self.number2symbol = {}
self.states = []
self.dfas = {}
self.labels = [(0, "EMPTY")]
self.keywords = {}
self.tokens = {}
self.symbol2label = {}
self.start = 256
def dump(self, filename):
"""Dump the grammar tables to a pickle file."""
f = open(filename, "wb")
pickle.dump(self.__dict__, f, 2)
f.close()
def load(self, filename):
"""Load the grammar tables from a pickle file."""
f = open(filename, "rb")
d = pickle.load(f)
f.close()
self.__dict__.update(d)
def copy(self):
"""
Copy the grammar.
"""
new = self.__class__()
for dict_attr in ("symbol2number", "number2symbol", "dfas", "keywords",
"tokens", "symbol2label"):
setattr(new, dict_attr, getattr(self, dict_attr).copy())
new.labels = self.labels[:]
new.states = self.states[:]
new.start = self.start
return new
def report(self):
"""Dump the grammar tables to standard output, for debugging."""
from pprint import pprint
print "s2n"
pprint(self.symbol2number)
print "n2s"
pprint(self.number2symbol)
print "states"
pprint(self.states)
print "dfas"
pprint(self.dfas)
print "labels"
pprint(self.labels)
print "start", self.start
# Map from operator to number (since tokenize doesn't do this)
opmap_raw = """
( LPAR
) RPAR
[ LSQB
] RSQB
: COLON
, COMMA
; SEMI
+ PLUS
- MINUS
* STAR
/ SLASH
| VBAR
& AMPER
< LESS
> GREATER
= EQUAL
. DOT
% PERCENT
` BACKQUOTE
{ LBRACE
} RBRACE
@ AT
== EQEQUAL
!= NOTEQUAL
<> NOTEQUAL
<= LESSEQUAL
>= GREATEREQUAL
~ TILDE
^ CIRCUMFLEX
<< LEFTSHIFT
>> RIGHTSHIFT
** DOUBLESTAR
+= PLUSEQUAL
-= MINEQUAL
*= STAREQUAL
/= SLASHEQUAL
%= PERCENTEQUAL
&= AMPEREQUAL
|= VBAREQUAL
^= CIRCUMFLEXEQUAL
<<= LEFTSHIFTEQUAL
>>= RIGHTSHIFTEQUAL
**= DOUBLESTAREQUAL
// DOUBLESLASH
//= DOUBLESLASHEQUAL
-> RARROW
"""
opmap = {}
for line in opmap_raw.splitlines():
if line:
op, name = line.split()
opmap[op] = getattr(token, name)
|
