| 1 |
tim |
2469 |
/* ANTLR Translator Generator |
| 2 |
|
|
* Project led by Terence Parr at http://www.jGuru.com |
| 3 |
|
|
* Software rights: http://www.antlr.org/license.html |
| 4 |
|
|
* |
| 5 |
|
|
* $Id: TokenBuffer.cpp,v 1.1 2005-12-02 15:38:02 tim Exp $ |
| 6 |
|
|
*/ |
| 7 |
|
|
|
| 8 |
|
|
#include "antlr/TokenBuffer.hpp" |
| 9 |
|
|
|
| 10 |
|
|
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE |
| 11 |
|
|
namespace antlr { |
| 12 |
|
|
#endif |
| 13 |
|
|
|
| 14 |
|
|
/**A Stream of Token objects fed to the parser from a TokenStream that can |
| 15 |
|
|
* be rewound via mark()/rewind() methods. |
| 16 |
|
|
* <p> |
| 17 |
|
|
* A dynamic array is used to buffer up all the input tokens. Normally, |
| 18 |
|
|
* "k" tokens are stored in the buffer. More tokens may be stored during |
| 19 |
|
|
* guess mode (testing syntactic predicate), or when LT(i>k) is referenced. |
| 20 |
|
|
* Consumption of tokens is deferred. In other words, reading the next |
| 21 |
|
|
* token is not done by conume(), but deferred until needed by LA or LT. |
| 22 |
|
|
* <p> |
| 23 |
|
|
* |
| 24 |
|
|
* @see antlr.Token |
| 25 |
|
|
* @see antlr.TokenStream |
| 26 |
|
|
* @see antlr.TokenQueue |
| 27 |
|
|
*/ |
| 28 |
|
|
|
| 29 |
|
|
/** Create a token buffer */ |
| 30 |
|
|
TokenBuffer::TokenBuffer( TokenStream& inp ) |
| 31 |
|
|
: input(inp) |
| 32 |
|
|
, nMarkers(0) |
| 33 |
|
|
, markerOffset(0) |
| 34 |
|
|
, numToConsume(0) |
| 35 |
|
|
{ |
| 36 |
|
|
} |
| 37 |
|
|
|
| 38 |
|
|
TokenBuffer::~TokenBuffer( void ) |
| 39 |
|
|
{ |
| 40 |
|
|
} |
| 41 |
|
|
|
| 42 |
|
|
/** Ensure that the token buffer is sufficiently full */ |
| 43 |
|
|
void TokenBuffer::fill(unsigned int amount) |
| 44 |
|
|
{ |
| 45 |
|
|
syncConsume(); |
| 46 |
|
|
// Fill the buffer sufficiently to hold needed tokens |
| 47 |
|
|
while (queue.entries() < (amount + markerOffset)) |
| 48 |
|
|
{ |
| 49 |
|
|
// Append the next token |
| 50 |
|
|
queue.append(input.nextToken()); |
| 51 |
|
|
} |
| 52 |
|
|
} |
| 53 |
|
|
|
| 54 |
|
|
/** Get a lookahead token value */ |
| 55 |
|
|
int TokenBuffer::LA(unsigned int i) |
| 56 |
|
|
{ |
| 57 |
|
|
fill(i); |
| 58 |
|
|
return queue.elementAt(markerOffset+i-1)->getType(); |
| 59 |
|
|
} |
| 60 |
|
|
|
| 61 |
|
|
/** Get a lookahead token */ |
| 62 |
|
|
RefToken TokenBuffer::LT(unsigned int i) |
| 63 |
|
|
{ |
| 64 |
|
|
fill(i); |
| 65 |
|
|
return queue.elementAt(markerOffset+i-1); |
| 66 |
|
|
} |
| 67 |
|
|
|
| 68 |
|
|
/** Return an integer marker that can be used to rewind the buffer to |
| 69 |
|
|
* its current state. |
| 70 |
|
|
*/ |
| 71 |
|
|
unsigned int TokenBuffer::mark() |
| 72 |
|
|
{ |
| 73 |
|
|
syncConsume(); |
| 74 |
|
|
nMarkers++; |
| 75 |
|
|
return markerOffset; |
| 76 |
|
|
} |
| 77 |
|
|
|
| 78 |
|
|
/**Rewind the token buffer to a marker. |
| 79 |
|
|
* @param mark Marker returned previously from mark() |
| 80 |
|
|
*/ |
| 81 |
|
|
void TokenBuffer::rewind(unsigned int mark) |
| 82 |
|
|
{ |
| 83 |
|
|
syncConsume(); |
| 84 |
|
|
markerOffset=mark; |
| 85 |
|
|
nMarkers--; |
| 86 |
|
|
} |
| 87 |
|
|
|
| 88 |
|
|
/// Get number of non-consumed tokens |
| 89 |
|
|
unsigned int TokenBuffer::entries() const |
| 90 |
|
|
{ |
| 91 |
|
|
return queue.entries() - markerOffset; |
| 92 |
|
|
} |
| 93 |
|
|
|
| 94 |
|
|
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE |
| 95 |
|
|
} |
| 96 |
|
|
#endif |
