Package org.antlr.runtime.tree

Class BufferedTreeNodeStream

  • All Implemented Interfaces:
    IntStream, TreeNodeStream
    public class BufferedTreeNodeStream
extends 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

    • 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

      • nodes

        protected List<Object> 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 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​(Object tree)

      • BufferedTreeNodeStream

        public BufferedTreeNodeStream​(TreeAdaptor adaptor,
                              Object tree)

      • BufferedTreeNodeStream

        public BufferedTreeNodeStream​(TreeAdaptor adaptor,
                              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​(Object t)

      • getNodeIndex

        protected int getNodeIndex​(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 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 Object LT​(int k)
        Description copied from interface: TreeNodeStream
        Get tree node at current input pointer + k ahead where k==1 is next node. k<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 k<=n, return null. Return null for LT(0) and any index that results in an absolute address that is negative.

        This is analogous to TokenStream.LT(int), but this returns a tree node instead of a Token. Makes code generation identical for both parser and tree grammars.

        Specified by:
        LT in interface TreeNodeStream

      • getCurrentSymbol

        public Object getCurrentSymbol()

      • LB

        protected Object LB​(int k)
        Look backwards k nodes

      • getTreeSource

        public 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 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)

      • 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 Token.UP, Token.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

      • replaceChildren

        public void replaceChildren​(Object parent,
                            int startChildIndex,
                            int stopChildIndex,
                            Object t)
        Description copied from interface: TreeNodeStream
        Replace children of parent from index startChildIndex to stopChildIndex 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 String toTokenTypeString()
        Used for testing, just return the token type stream

      • toTokenString

        public String toTokenString​(int start,
                            int stop)
        Debugging

      • toString

        public String toString​(Object start,
                       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