Package org.antlr.runtime.debug
Class DebugTokenStream
- java.lang.Object
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- org.antlr.runtime.debug.DebugTokenStream
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- All Implemented Interfaces:
IntStream
,TokenStream
public class DebugTokenStream extends Object implements TokenStream
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Field Summary
Fields Modifier and Type Field Description protected DebugEventListener
dbg
protected boolean
initialStreamState
TokenStream
input
protected int
lastMarker
Track the last mark() call result value for use in rewind().
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Constructor Summary
Constructors Constructor Description DebugTokenStream(TokenStream input, DebugEventListener dbg)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
consume()
protected void
consumeInitialHiddenTokens()
Token
get(int i)
Get a token at an absolute index i; 0..n-1.String
getSourceName()
Where are you getting symbols from? Normally, implementations will pass the buck all the way to the lexer who can ask its input stream for the file name or whatever.TokenSource
getTokenSource()
Where is this stream pulling tokens from? This is not the name, but the object that provides Token objects.int
index()
Return the current input symbol index 0..n where n indicates the last symbol has been read.int
LA(int i)
Get int at current input pointer + i ahead where i=1 is next int.Token
LT(int i)
Get Token at current input pointer + i ahead where i=1 is next Token.int
mark()
Tell the stream to start buffering if it hasn't already.int
range()
How far ahead has the stream been asked to look? The return value is a valid index from 0..n-1.void
release(int marker)
You may want to commit to a backtrack but don't want to force the stream to keep bookkeeping objects around for a marker that is no longer necessary.void
rewind()
Rewind to the input position of the last marker.void
rewind(int marker)
Reset the stream so that next call to index would return marker.void
seek(int index)
Set the input cursor to the position indicated by index.void
setDebugListener(DebugEventListener dbg)
int
size()
Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing.String
toString()
String
toString(int start, int stop)
Return the text of all tokens from start to stop, inclusive.String
toString(Token start, Token stop)
Because the user is not required to use a token with an index stored in it, we must provide a means for two token objects themselves to indicate the start/end location.
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Field Detail
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dbg
protected DebugEventListener dbg
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input
public TokenStream input
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initialStreamState
protected boolean initialStreamState
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lastMarker
protected int lastMarker
Track the last mark() call result value for use in rewind().
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Constructor Detail
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DebugTokenStream
public DebugTokenStream(TokenStream input, DebugEventListener dbg)
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Method Detail
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setDebugListener
public void setDebugListener(DebugEventListener dbg)
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consumeInitialHiddenTokens
protected void consumeInitialHiddenTokens()
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LT
public Token LT(int i)
Description copied from interface:TokenStream
Get Token at current input pointer + i ahead where i=1 is next Token. i<0 indicates tokens in the past. So -1 is previous token and -2 is two tokens ago. LT(0) is undefined. For i>=n, return Token.EOFToken. Return null for LT(0) and any index that results in an absolute address that is negative.- Specified by:
LT
in interfaceTokenStream
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LA
public int LA(int i)
Description copied from interface:IntStream
Get int at current input pointer + i ahead where i=1 is next int. Negative indexes are allowed. LA(-1) is previous token (token just matched). LA(-i) where i is before first token should yield -1, invalid char / EOF.
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get
public Token get(int i)
Description copied from interface:TokenStream
Get a token at an absolute index i; 0..n-1. This is really only needed for profiling and debugging and token stream rewriting. If you don't want to buffer up tokens, then this method makes no sense for you. Naturally you can't use the rewrite stream feature. I believe DebugTokenStream can easily be altered to not use this method, removing the dependency.- Specified by:
get
in interfaceTokenStream
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mark
public int mark()
Description copied from interface:IntStream
Tell the stream to start buffering if it hasn't already. Return current input position, index(), or some other marker so that when passed to rewind() you get back to the same spot. rewind(mark()) should not affect the input cursor. The Lexer track line/col info as well as input index so its markers are not pure input indexes. Same for tree node streams.
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index
public int index()
Description copied from interface:IntStream
Return the current input symbol index 0..n where n indicates the last symbol has been read. The index is the symbol about to be read not the most recently read symbol.
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range
public int range()
Description copied from interface:TokenStream
How far ahead has the stream been asked to look? The return value is a valid index from 0..n-1.- Specified by:
range
in interfaceTokenStream
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rewind
public void rewind(int marker)
Description copied from interface:IntStream
Reset the stream so that next call to index would return marker. The marker will usually be index() but it doesn't have to be. It's just a marker to indicate what state the stream was in. This is essentially calling release() and seek(). If there are markers created after this marker argument, this routine must unroll them like a stack. Assume the state the stream was in when this marker was created.
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rewind
public void rewind()
Description copied from interface:IntStream
Rewind to the input position of the last marker. Used currently only after a cyclic DFA and just before starting a sem/syn predicate to get the input position back to the start of the decision. Do not "pop" the marker off the state. mark(i) and rewind(i) should balance still. It is like invoking rewind(last marker) but it should not "pop" the marker off. It's like seek(last marker's input position).
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release
public void release(int marker)
Description copied from interface:IntStream
You may want to commit to a backtrack but don't want to force the stream to keep bookkeeping objects around for a marker that is no longer necessary. This will have the same behavior as rewind() except it releases resources without the backward seek. This must throw away resources for all markers back to the marker argument. So if you're nested 5 levels of mark(), and then release(2) you have to release resources for depths 2..5.
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seek
public void seek(int index)
Description copied from interface:IntStream
Set the input cursor to the position indicated by index. This is normally used to seek ahead in the input stream. No buffering is required to do this unless you know your stream will use seek to move backwards such as when backtracking. This is different from rewind in its multi-directional requirement and in that its argument is strictly an input cursor (index). For char streams, seeking forward must update the stream state such as line number. For seeking backwards, you will be presumably backtracking using the mark/rewind mechanism that restores state and so this method does not need to update state when seeking backwards. Currently, this method is only used for efficient backtracking using memoization, but in the future it may be used for incremental parsing. The index is 0..n-1. A seek to position i means that LA(1) will return the ith symbol. So, seeking to 0 means LA(1) will return the first element in the stream.
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size
public int size()
Description copied from interface:IntStream
Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing. This value includes a single EOF.
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getTokenSource
public TokenSource getTokenSource()
Description copied from interface:TokenStream
Where is this stream pulling tokens from? This is not the name, but the object that provides Token objects.- Specified by:
getTokenSource
in interfaceTokenStream
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getSourceName
public String getSourceName()
Description copied from interface:IntStream
Where are you getting symbols from? Normally, implementations will pass the buck all the way to the lexer who can ask its input stream for the file name or whatever.- Specified by:
getSourceName
in interfaceIntStream
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toString
public String toString(int start, int stop)
Description copied from interface:TokenStream
Return the text of all tokens from start to stop, inclusive. If the stream does not buffer all the tokens then it can just return "" or null; Users should not access $ruleLabel.text in an action of course in that case.- Specified by:
toString
in interfaceTokenStream
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toString
public String toString(Token start, Token stop)
Description copied from interface:TokenStream
Because the user is not required to use a token with an index stored in it, we must provide a means for two token objects themselves to indicate the start/end location. Most often this will just delegate to the other toString(int,int). This is also parallel with the TreeNodeStream.toString(Object,Object).- Specified by:
toString
in interfaceTokenStream
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