Package org.antlr.v4.runtime

Class UnbufferedTokenStream<T extends Token>

    • Field Detail

      • tokens

        protected Token[] tokens
        A moving window buffer of the data being scanned. While there's a marker, we keep adding to buffer. Otherwise, consume() resets so we start filling at index 0 again.

      • n

        protected int n
        The number of tokens currently in tokens.

        This is not the buffer capacity, that's tokens.length.

      • p

        protected int p
        0..n-1 index into tokens of next token.

        The LT(1) token is tokens[p]. If p == n, we are out of buffered tokens.

      • numMarkers

        protected int numMarkers
        Count up with mark() and down with release(). When we release() the last mark, numMarkers reaches 0 and we reset the buffer. Copy tokens[p]..tokens[n-1] to tokens[0]..tokens[(n-1)-p].

      • lastToken

        protected Token lastToken
        This is the LT(-1) token for the current position.

      • lastTokenBufferStart

        protected Token lastTokenBufferStart
        When numMarkers > 0, this is the LT(-1) token for the first token in tokens. Otherwise, this is null.

      • currentTokenIndex

        protected int currentTokenIndex
        Absolute token index. It's the index of the token about to be read via LT(1). Goes from 0 to the number of tokens in the entire stream, although the stream size is unknown before the end is reached.

        This value is used to set the token indexes if the stream provides tokens that implement WritableToken.

    • Constructor Detail

      • UnbufferedTokenStream

        public UnbufferedTokenStream​(TokenSource tokenSource)

      • UnbufferedTokenStream

        public UnbufferedTokenStream​(TokenSource tokenSource,
                             int bufferSize)

    • Method Detail

      • get

        public Token get​(int i)
        Description copied from interface: TokenStream
        Gets the Token at the specified index in the stream. When the preconditions of this method are met, the return value is non-null.

        The preconditions for this method are the same as the preconditions of IntStream.seek(int). If the behavior of seek(index) is unspecified for the current state and given index, then the behavior of this method is also unspecified.

        The symbol referred to by index differs from seek() only in the case of filtering streams where index lies before the end of the stream. Unlike seek(), this method does not adjust index to point to a non-ignored symbol.

        Specified by:
        get in interface TokenStream

      • LT

        public Token LT​(int i)
        Description copied from interface: TokenStream
        Get the Token instance associated with the value returned by LA(k). This method has the same pre- and post-conditions as IntStream.LA(int). In addition, when the preconditions of this method are met, the return value is non-null and the value of LT(k).getType()==LA(k).
        Specified by:
        LT in interface TokenStream
        See Also:
        IntStream.LA(int)

      • LA

        public int LA​(int i)
        Description copied from interface: IntStream
        Gets the value of the symbol at offset i from the current position. When i==1, this method returns the value of the current symbol in the stream (which is the next symbol to be consumed). When i==-1, this method returns the value of the previously read symbol in the stream. It is not valid to call this method with i==0, but the specific behavior is unspecified because this method is frequently called from performance-critical code.

        This method is guaranteed to succeed if any of the following are true:

        • i>0
        • i==-1 and index() returns a value greater than the value of index() after the stream was constructed and LA(1) was called in that order. Specifying the current index() relative to the index after the stream was created allows for filtering implementations that do not return every symbol from the underlying source. Specifying the call to LA(1) allows for lazily initialized streams.
        • LA(i) refers to a symbol consumed within a marked region that has not yet been released.

        If i represents a position at or beyond the end of the stream, this method returns IntStream.EOF.

        The return value is unspecified if i<0 and fewer than -i calls to consume() have occurred from the beginning of the stream before calling this method.

        Specified by:
        LA in interface IntStream

      • getText

        public String getText()
        Description copied from interface: TokenStream
        Return the text of all tokens in the stream. This method behaves like the following code, including potential exceptions from the calls to IntStream.size() and TokenStream.getText(Interval), but may be optimized by the specific implementation. 
         TokenStream stream = ...;
 String text = stream.getText(new Interval(0, stream.size()));
        Specified by:
        getText in interface TokenStream
        Returns:
        The text of all tokens in the stream.

      • getText

        public String getText​(RuleContext ctx)
        Description copied from interface: TokenStream
        Return the text of all tokens in the source interval of the specified context. This method behaves like the following code, including potential exceptions from the call to TokenStream.getText(Interval), but may be optimized by the specific implementation.

        If ctx.getSourceInterval() does not return a valid interval of tokens provided by this stream, the behavior is unspecified.

         TokenStream stream = ...;
 String text = stream.getText(ctx.getSourceInterval());
        Specified by:
        getText in interface TokenStream
        Parameters:
        ctx - The context providing the source interval of tokens to get text for.
        Returns:
        The text of all tokens within the source interval of ctx.

      • getText

        public String getText​(Token start,
                      Token stop)
        Description copied from interface: TokenStream
        Return the text of all tokens in this stream between start and stop (inclusive).

        If the specified start or stop token was not provided by this stream, or if the stop occurred before the start token, the behavior is unspecified.

        For streams which ensure that the Token.getTokenIndex() method is accurate for all of its provided tokens, this method behaves like the following code. Other streams may implement this method in other ways provided the behavior is consistent with this at a high level.

         TokenStream stream = ...;
 String text = "";
 for (int i = start.getTokenIndex(); i <= stop.getTokenIndex(); i++) {
   text += stream.get(i).getText();
 }
        Specified by:
        getText in interface TokenStream
        Parameters:
        start - The first token in the interval to get text for.
        stop - The last token in the interval to get text for (inclusive).
        Returns:
        The text of all tokens lying between the specified start and stop tokens.

      • consume

        public void consume()
        Description copied from interface: IntStream
        Consumes the current symbol in the stream. This method has the following effects:
        • Forward movement: The value of index() before calling this method is less than the value of index() after calling this method.
        • Ordered lookahead: The value of LA(1) before calling this method becomes the value of LA(-1) after calling this method.
        Note that calling this method does not guarantee that index() is incremented by exactly 1, as that would preclude the ability to implement filtering streams (e.g. CommonTokenStream which distinguishes between "on-channel" and "off-channel" tokens).
        Specified by:
        consume in interface IntStream

      • sync

        protected void sync​(int want)
        Make sure we have 'need' elements from current position p. Last valid p index is tokens.length-1. p+need-1 is the tokens index 'need' elements ahead. If we need 1 element, (p+1-1)==p must be less than tokens.length.

      • fill

        protected int fill​(int n)
        Add n elements to the buffer. Returns the number of tokens actually added to the buffer. If the return value is less than n, then EOF was reached before n tokens could be added.

      • add

        protected void add​(Token t)

      • mark

        public int mark()
        Return a marker that we can release later.

        The specific marker value used for this class allows for some level of protection against misuse where seek() is called on a mark or release() is called in the wrong order.

        Specified by:
        mark in interface IntStream
        Returns:
        An opaque marker which should be passed to release() when the marked range is no longer required.

      • release

        public void release​(int marker)
        Description copied from interface: IntStream
        This method releases a marked range created by a call to mark(). Calls to release() must appear in the reverse order of the corresponding calls to mark(). If a mark is released twice, or if marks are not released in reverse order of the corresponding calls to mark(), the behavior is unspecified.

        For more information and an example, see IntStream.mark().

        Specified by:
        release in interface IntStream
        Parameters:
        marker - A marker returned by a call to mark().
        See Also:
        IntStream.mark()

      • index

        public int index()
        Description copied from interface: IntStream
        Return the index into the stream of the input symbol referred to by LA(1).

        The behavior of this method is unspecified if no call to an initializing method has occurred after this stream was constructed.

        Specified by:
        index in interface IntStream

      • seek

        public void seek​(int index)
        Description copied from interface: IntStream
        Set the input cursor to the position indicated by index. If the specified index lies past the end of the stream, the operation behaves as though index was the index of the EOF symbol. After this method returns without throwing an exception, then at least one of the following will be true.
        • index() will return the index of the first symbol appearing at or after the specified index. Specifically, implementations which filter their sources should automatically adjust index forward the minimum amount required for the operation to target a non-ignored symbol.
        • LA(1) returns IntStream.EOF
        This operation is guaranteed to not throw an exception if index lies within a marked region. For more information on marked regions, see IntStream.mark(). The behavior of this method is unspecified if no call to an initializing method has occurred after this stream was constructed.
        Specified by:
        seek in interface IntStream
        Parameters:
        index - The absolute index to seek to.

      • size

        public int size()
        Description copied from interface: IntStream
        Returns the total number of symbols in the stream, including a single EOF symbol.
        Specified by:
        size in interface IntStream

      • getText

        public String getText​(Interval interval)
        Description copied from interface: TokenStream
        Return the text of all tokens within the specified interval. This method behaves like the following code (including potential exceptions for violating preconditions of TokenStream.get(int), but may be optimized by the specific implementation. 
         TokenStream stream = ...;
 String text = "";
 for (int i = interval.a; i <= interval.b; i++) {
   text += stream.get(i).getText();
 }
        Specified by:
        getText in interface TokenStream
        Parameters:
        interval - The interval of tokens within this stream to get text for.
        Returns:
        The text of all tokens within the specified interval in this stream.

      • getBufferStartIndex

        protected final int getBufferStartIndex()