Package org.antlr.runtime.misc
Class LookaheadStream<T>
java.lang.Object
org.antlr.runtime.misc.FastQueue<T>
org.antlr.runtime.misc.LookaheadStream<T>
- Direct Known Subclasses:
CommonTreeNodeStream
A lookahead queue that knows how to mark/release locations
in the buffer for backtracking purposes. Any markers force the FastQueue
superclass to keep all tokens until no more markers; then can reset
to avoid growing a huge buffer.
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Field Summary
FieldsModifier and TypeFieldDescriptionReturned by nextElement upon end of stream; we add to buffer alsoprotected int
Set to buffer index of eof when nextElement returns eofprotected int
Track the last mark() call result value for use in rewind().protected int
tracks how deep mark() calls are nestedstatic final int
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
consume()
Make sure we have at least one element to remove, even if EOFvoid
fill
(int n) add n elements to bufferint
index()
protected Object
LB
(int k) Look backwards k nodesLT
(int k) int
mark()
abstract T
Implement nextElement to supply a stream of elements to this lookahead buffer.void
release
(int marker) remove()
Get and remove first element in queue; override FastQueue.remove()void
reset()
void
rewind()
void
rewind
(int marker) void
seek
(int index) Seek to a 0-indexed position within data buffer.int
size()
Size of entire stream is unknown; we only know buffer size from FastQueuevoid
sync
(int need) Make sure we have 'need' elements from current position p.
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Field Details
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UNINITIALIZED_EOF_ELEMENT_INDEX
public static final int UNINITIALIZED_EOF_ELEMENT_INDEX- See Also:
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eofElementIndex
protected int eofElementIndexSet to buffer index of eof when nextElement returns eof -
eof
Returned by nextElement upon end of stream; we add to buffer also -
lastMarker
protected int lastMarkerTrack the last mark() call result value for use in rewind(). -
markDepth
protected int markDepthtracks how deep mark() calls are nested
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Constructor Details
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LookaheadStream
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Method Details
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reset
public void reset() -
nextElement
Implement nextElement to supply a stream of elements to this lookahead buffer. Return eof upon end of the stream we're pulling from. -
remove
Get and remove first element in queue; override FastQueue.remove() -
consume
public void consume()Make sure we have at least one element to remove, even if EOF -
sync
public void sync(int need) Make sure we have 'need' elements from current position p. Last valid p index is data.size()-1. p+need-1 is the data index 'need' elements ahead. If we need 1 element, (p+1-1)==p must be < data.size(). -
fill
public void fill(int n) add n elements to buffer -
size
public int size()Size of entire stream is unknown; we only know buffer size from FastQueue -
LT
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LB
Look backwards k nodes -
getCurrentSymbol
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index
public int index() -
mark
public int mark() -
release
public void release(int marker) -
rewind
public void rewind(int marker) -
rewind
public void rewind() -
seek
public void seek(int index) Seek to a 0-indexed position within data buffer. Can't handle case where you seek beyond end of existing buffer. Normally used to seek backwards in the buffer. Does not force loading of nodes.
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