org.antlr.runtime.tree
Class BufferedTreeNodeStream

java.lang.Object
  extended by org.antlr.runtime.tree.BufferedTreeNodeStream
All Implemented Interfaces:
IntStream, TreeNodeStream

public class BufferedTreeNodeStream
extends java.lang.Object
implements TreeNodeStream

A buffered stream of tree nodes. Nodes can be from a tree of ANY kind. This node stream sucks all nodes out of the tree specified in the constructor during construction and makes pointers into the tree using an array of Object pointers. The stream necessarily includes pointers to DOWN and UP and EOF nodes. This stream knows how to mark/release for backtracking. This stream is most suitable for tree interpreters that need to jump around a lot or for tree parsers requiring speed (at cost of memory). There is some duplicated functionality here with UnBufferedTreeNodeStream but just in bookkeeping, not tree walking etc... TARGET DEVELOPERS: This is the old CommonTreeNodeStream that buffered up entire node stream. No need to implement really as new CommonTreeNodeStream is much better and covers what we need.

See Also:
CommonTreeNodeStream

Nested Class Summary
protected  class BufferedTreeNodeStream.StreamIterator
           
 
Field Summary
protected  IntArray calls
          Stack of indexes used for push/pop calls
static int DEFAULT_INITIAL_BUFFER_SIZE
           
protected  java.lang.Object down
           
protected  java.lang.Object eof
           
static int INITIAL_CALL_STACK_SIZE
           
protected  int lastMarker
          Track the last mark() call result value for use in rewind().
protected  java.util.List nodes
          The complete mapping from stream index to tree node.
protected  int p
          The index into the nodes list of the current node (next node to consume).
protected  java.lang.Object root
          Pull nodes from which tree?
protected  TokenStream tokens
          IF this tree (root) was created from a token stream, track it.
protected  boolean uniqueNavigationNodes
          Reuse same DOWN, UP navigation nodes unless this is true
protected  java.lang.Object up
           
 
Constructor Summary
BufferedTreeNodeStream(java.lang.Object tree)
           
BufferedTreeNodeStream(TreeAdaptor adaptor, java.lang.Object tree)
           
BufferedTreeNodeStream(TreeAdaptor adaptor, java.lang.Object tree, int initialBufferSize)
           
 
Method Summary
protected  void addNavigationNode(int ttype)
          As we flatten the tree, we use UP, DOWN nodes to represent the tree structure.
 void consume()
           
protected  void fillBuffer()
          Walk tree with depth-first-search and fill nodes buffer.
 void fillBuffer(java.lang.Object t)
           
 java.lang.Object get(int i)
          Get a tree node at an absolute index i; 0..n-1.
 java.lang.Object getCurrentSymbol()
           
protected  int getNodeIndex(java.lang.Object node)
          What is the stream index for node? 0..n-1 Return -1 if node not found.
 java.lang.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.
 TokenStream getTokenStream()
          If the tree associated with this stream was created from a TokenStream, you can specify it here.
 TreeAdaptor getTreeAdaptor()
          What adaptor can tell me how to interpret/navigate nodes and trees.
 java.lang.Object getTreeSource()
          Where is this stream pulling nodes from? This is not the name, but the object that provides node objects.
 boolean hasUniqueNavigationNodes()
           
 int index()
          Return the current input symbol index 0..n where n indicates the last symbol has been read.
 java.util.Iterator iterator()
           
 int LA(int i)
          Get int at current input pointer + i ahead where i=1 is next int.
protected  java.lang.Object LB(int k)
          Look backwards k nodes
 java.lang.Object LT(int k)
          Get tree node at current input pointer + i ahead where i=1 is next node.
 int mark()
          Tell the stream to start buffering if it hasn't already.
 int pop()
          Seek back to previous index saved during last push() call.
 void push(int index)
          Make stream jump to a new location, saving old location.
 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 replaceChildren(java.lang.Object parent, int startChildIndex, int stopChildIndex, java.lang.Object t)
          Replace from start to stop child index of parent with t, which might be a list.
 void reset()
          Reset the tree node stream in such a way that it acts like a freshly constructed stream.
 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 setTokenStream(TokenStream tokens)
           
 void setTreeAdaptor(TreeAdaptor adaptor)
           
 void setUniqueNavigationNodes(boolean uniqueNavigationNodes)
          As we flatten the tree, we use UP, DOWN nodes to represent the tree structure.
 int size()
          Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing.
 java.lang.String toString(java.lang.Object start, java.lang.Object stop)
          Return the text of all nodes from start to stop, inclusive.
 java.lang.String toTokenString(int start, int stop)
          Debugging
 java.lang.String toTokenTypeString()
          Used for testing, just return the token type stream
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEFAULT_INITIAL_BUFFER_SIZE

public static final int DEFAULT_INITIAL_BUFFER_SIZE
See Also:
Constant Field Values

INITIAL_CALL_STACK_SIZE

public static final int INITIAL_CALL_STACK_SIZE
See Also:
Constant Field Values

down

protected java.lang.Object down

up

protected java.lang.Object up

eof

protected java.lang.Object eof

nodes

protected java.util.List nodes
The complete mapping from stream index to tree node. This buffer includes pointers to DOWN, UP, and EOF nodes. It is built upon ctor invocation. The elements are type Object as we don't what the trees look like. Load upon first need of the buffer so we can set token types of interest for reverseIndexing. Slows us down a wee bit to do all of the if p==-1 testing everywhere though.


root

protected java.lang.Object root
Pull nodes from which tree?


tokens

protected TokenStream tokens
IF this tree (root) was created from a token stream, track it.


uniqueNavigationNodes

protected boolean uniqueNavigationNodes
Reuse same DOWN, UP navigation nodes unless this is true


p

protected int p
The index into the nodes list of the current node (next node to consume). If -1, nodes array not filled yet.


lastMarker

protected int lastMarker
Track the last mark() call result value for use in rewind().


calls

protected IntArray calls
Stack of indexes used for push/pop calls

Constructor Detail

BufferedTreeNodeStream

public BufferedTreeNodeStream(java.lang.Object tree)

BufferedTreeNodeStream

public BufferedTreeNodeStream(TreeAdaptor adaptor,
                              java.lang.Object tree)

BufferedTreeNodeStream

public BufferedTreeNodeStream(TreeAdaptor adaptor,
                              java.lang.Object tree,
                              int initialBufferSize)
Method Detail

fillBuffer

protected void fillBuffer()
Walk tree with depth-first-search and fill nodes buffer. Don't do DOWN, UP nodes if its a list (t is isNil).


fillBuffer

public void fillBuffer(java.lang.Object t)

getNodeIndex

protected int getNodeIndex(java.lang.Object node)
What is the stream index for node? 0..n-1 Return -1 if node not found.


addNavigationNode

protected void addNavigationNode(int ttype)
As we flatten the tree, we use UP, DOWN nodes to represent the tree structure. When debugging we need unique nodes so instantiate new ones when uniqueNavigationNodes is true.


get

public java.lang.Object get(int i)
Description copied from interface: TreeNodeStream
Get a tree node at an absolute index i; 0..n-1. If you don't want to buffer up nodes, then this method makes no sense for you.

Specified by:
get in interface TreeNodeStream

LT

public java.lang.Object LT(int k)
Description copied from interface: TreeNodeStream
Get tree node at current input pointer + i ahead where i=1 is next node. i<0 indicates nodes in the past. So LT(-1) is previous node, but implementations are not required to provide results for k < -1. LT(0) is undefined. For i>=n, return null. Return null for LT(0) and any index that results in an absolute address that is negative. This is analogus to the LT() method of the TokenStream, but this returns a tree node instead of a token. Makes code gen identical for both parser and tree grammars. :)

Specified by:
LT in interface TreeNodeStream

getCurrentSymbol

public java.lang.Object getCurrentSymbol()

LB

protected java.lang.Object LB(int k)
Look backwards k nodes


getTreeSource

public java.lang.Object getTreeSource()
Description copied from interface: TreeNodeStream
Where is this stream pulling nodes from? This is not the name, but the object that provides node objects.

Specified by:
getTreeSource in interface TreeNodeStream

getSourceName

public java.lang.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 interface IntStream

getTokenStream

public TokenStream getTokenStream()
Description copied from interface: TreeNodeStream
If the tree associated with this stream was created from a TokenStream, you can specify it here. Used to do rule $text attribute in tree parser. Optional unless you use tree parser rule text attribute or output=template and rewrite=true options.

Specified by:
getTokenStream in interface TreeNodeStream

setTokenStream

public void setTokenStream(TokenStream tokens)

getTreeAdaptor

public TreeAdaptor getTreeAdaptor()
Description copied from interface: TreeNodeStream
What adaptor can tell me how to interpret/navigate nodes and trees. E.g., get text of a node.

Specified by:
getTreeAdaptor in interface TreeNodeStream

setTreeAdaptor

public void setTreeAdaptor(TreeAdaptor adaptor)

hasUniqueNavigationNodes

public boolean hasUniqueNavigationNodes()

setUniqueNavigationNodes

public void setUniqueNavigationNodes(boolean uniqueNavigationNodes)
Description copied from interface: TreeNodeStream
As we flatten the tree, we use UP, DOWN nodes to represent the tree structure. When debugging we need unique nodes so we have to instantiate new ones. When doing normal tree parsing, it's slow and a waste of memory to create unique navigation nodes. Default should be false;

Specified by:
setUniqueNavigationNodes in interface TreeNodeStream

consume

public void consume()
Specified by:
consume in interface IntStream

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.

Specified by:
LA in interface IntStream

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.

Specified by:
mark in interface IntStream

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.

Specified by:
release in interface IntStream

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.

Specified by:
index in interface IntStream

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.

Specified by:
rewind in interface IntStream

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).

Specified by:
rewind in interface IntStream

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.

Specified by:
seek in interface IntStream

push

public void push(int index)
Make stream jump to a new location, saving old location. Switch back with pop().


pop

public int pop()
Seek back to previous index saved during last push() call. Return top of stack (return index).


reset

public void reset()
Description copied from interface: TreeNodeStream
Reset the tree node stream in such a way that it acts like a freshly constructed stream.

Specified by:
reset in interface TreeNodeStream

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.

Specified by:
size in interface IntStream

iterator

public java.util.Iterator iterator()

replaceChildren

public void replaceChildren(java.lang.Object parent,
                            int startChildIndex,
                            int stopChildIndex,
                            java.lang.Object t)
Description copied from interface: TreeNodeStream
Replace from start to stop child index of parent with t, which might be a list. Number of children may be different after this call. The stream is notified because it is walking the tree and might need to know you are monkeying with the underlying tree. Also, it might be able to modify the node stream to avoid restreaming for future phases. If parent is null, don't do anything; must be at root of overall tree. Can't replace whatever points to the parent externally. Do nothing.

Specified by:
replaceChildren in interface TreeNodeStream

toTokenTypeString

public java.lang.String toTokenTypeString()
Used for testing, just return the token type stream


toTokenString

public java.lang.String toTokenString(int start,
                                      int stop)
Debugging


toString

public java.lang.String toString(java.lang.Object start,
                                 java.lang.Object stop)
Description copied from interface: TreeNodeStream
Return the text of all nodes from start to stop, inclusive. If the stream does not buffer all the nodes then it can still walk recursively from start until stop. You can always return null or "" too, but users should not access $ruleLabel.text in an action of course in that case.

Specified by:
toString in interface TreeNodeStream


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