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
|
/**
* <b>SOFTWARE RIGHTS</b>
* <p>
* ANTLR 2.6.0 MageLang Insitute, 1998
* <p>
* We reserve no legal rights to the ANTLR--it is fully in the
* public domain. An individual or company may do whatever
* they wish with source code distributed with ANTLR or the
* code generated by ANTLR, including the incorporation of
* ANTLR, or its output, into commerical software.
* <p>
* We encourage users to develop software with ANTLR. However,
* we do ask that credit is given to us for developing
* ANTLR. By "credit", we mean that if you use ANTLR or
* incorporate any source code into one of your programs
* (commercial product, research project, or otherwise) that
* you acknowledge this fact somewhere in the documentation,
* research report, etc... If you like ANTLR and have
* developed a nice tool with the output, please mention that
* you developed it using ANTLR. In addition, we ask that the
* headers remain intact in our source code. As long as these
* guidelines are kept, we expect to continue enhancing this
* system and expect to make other tools available as they are
* completed.
* <p>
* The ANTLR gang:
* @version ANTLR 2.6.0 MageLang Insitute, 1998
* @author Terence Parr, <a href=http://www.MageLang.com>MageLang Institute</a>
* @author <br>John Lilley, <a href=http://www.Empathy.com>Empathy Software</a>
* @author <br><a href="mailto:pete@yamuna.demon.co.uk">Pete Wells</a>
*/
#include "Antlr/TokenBuffer.hpp"
/**A Stream of Token objects fed to the parser from a TokenStream that can
* be rewound via mark()/rewind() methods.
* <p>
* A dynamic array is used to buffer up all the input tokens. Normally,
* "k" tokens are stored in the buffer. More tokens may be stored during
* guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
* Consumption of tokens is deferred. In other words, reading the next
* token is not done by conume(), but deferred until needed by LA or LT.
* <p>
*
* @see antlr.Token
* @see antlr.TokenStream
* @see antlr.TokenQueue
*/
/** Create a token buffer */
TokenBuffer::TokenBuffer(TokenStream& input_)
: input(input_)
{ nMarkers=0; markerOffset=0; numToConsume=0; }
/** Mark another token for deferred consumption */
void TokenBuffer::consume()
{ numToConsume++; }
/** Ensure that the token buffer is sufficiently full */
void TokenBuffer::fill(int amount)
{
syncConsume();
// Fill the buffer sufficiently to hold needed tokens
while (queue.entries() < size_t(amount + markerOffset)) {
// Append the next token
queue.append(input.nextToken());
}
}
/** Get a lookahead token value */
int TokenBuffer::LA(int i)
{
fill(i);
return queue.elementAt(markerOffset+i-1)->type;
}
/** Get a lookahead token */
RefToken TokenBuffer::LT(int i)
{
fill(i);
return queue.elementAt(markerOffset+i-1);
}
/**Return an integer marker that can be used to rewind the buffer to
* its current state.
*/
int TokenBuffer::mark()
{
syncConsume();
nMarkers++;
return markerOffset;
}
/**Rewind the token buffer to a marker.
* @param mark Marker returned previously from mark()
*/
void TokenBuffer::rewind(int mark)
{
syncConsume();
markerOffset=mark;
nMarkers--;
}
/** Sync up deferred consumption */
void TokenBuffer::syncConsume()
{
while (numToConsume > 0) {
if (nMarkers > 0) {
// guess mode -- leave leading tokens and bump offset.
markerOffset++;
} else {
// normal mode -- remove first token
queue.removeFirst();
}
numToConsume--;
}
}
|
