antlr4ts/IntStream.d.ts

ANTLR 4 runtime for JavaScript written in Typescript

/*!
 * Copyright 2016 The ANTLR Project. All rights reserved.
 * Licensed under the BSD-3-Clause license. See LICENSE file in the project root for license information.
 */
export declare namespace IntStream {
    /**
     * The value returned by {@link #LA LA()} when the end of the stream is
     * reached.
     */
    const EOF: number;
    /**
     * The value returned by {@link #getSourceName} when the actual name of the
     * underlying source is not known.
     */
    const UNKNOWN_SOURCE_NAME: string;
}
/**
 * A simple stream of symbols whose values are represented as integers. This
 * interface provides *marked ranges* with support for a minimum level
 * of buffering necessary to implement arbitrary lookahead during prediction.
 * For more information on marked ranges, see {@link #mark}.
 *
 * **Initializing Methods:** Some methods in this interface have
 * unspecified behavior if no call to an initializing method has occurred after
 * the stream was constructed. The following is a list of initializing methods:
 *
 * * {@link #LA}
 * * {@link #consume}
 * * {@link #size}
 */
export 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. {@link CommonTokenStream} which distinguishes
     * between "on-channel" and "off-channel" tokens).
     *
     * @throws IllegalStateException if an attempt is made to consume the
     * end of the stream (i.e. if `LA(1)==`{@link #EOF EOF} before calling
     * `consume`).
     */
    consume(): void;
    /**
     * 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 {@link #EOF}.
     *
     * The return value is unspecified if `i<0` and fewer than `-i`
     * calls to {@link #consume consume()} have occurred from the beginning of
     * the stream before calling this method.
     *
     * @throws UnsupportedOperationException if the stream does not support
     * retrieving the value of the specified symbol
     */
    LA(i: number): number;
    /**
     * A mark provides a guarantee that {@link #seek seek()} operations will be
     * valid over a "marked range" extending from the index where `mark()`
     * was called to the current `index`. This allows the use of
     * streaming input sources by specifying the minimum buffering requirements
     * to support arbitrary lookahead during prediction.
     *
     * The returned mark is an opaque handle (type `int`) which is passed
     * to {@link #release release()} when the guarantees provided by the marked
     * range are no longer necessary. When calls to
     * `mark()`/`release()` are nested, the marks must be released
     * in reverse order of which they were obtained. Since marked regions are
     * used during performance-critical sections of prediction, the specific
     * behavior of invalid usage is unspecified (i.e. a mark is not released, or
     * a mark is released twice, or marks are not released in reverse order from
     * which they were created).
     *
     * The behavior of this method is unspecified if no call to an
     * {@link IntStream initializing method} has occurred after this stream was
     * constructed.
     *
     * This method does not change the current position in the input stream.
     *
     * The following example shows the use of {@link #mark mark()},
     * {@link #release release(mark)}, `index`, and
     * {@link #seek seek(index)} as part of an operation to safely work within a
     * marked region, then restore the stream position to its original value and
     * release the mark.
     *
     * ```
     * IntStream stream = ...;
     * int index = -1;
     * int mark = stream.mark();
     * try {
     *   index = stream.index;
     *   // perform work here...
     * } finally {
     *   if (index != -1) {
     *     stream.seek(index);
     *   }
     *   stream.release(mark);
     * }
     * ```
     *
     * @returns An opaque marker which should be passed to
     * {@link #release release()} when the marked range is no longer required.
     */
    mark(): number;
    /**
     * This method releases a marked range created by a call to
     * {@link #mark 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 {@link #mark}.
     *
     * @param marker A marker returned by a call to `mark()`.
     * @see #mark
     */
    release(marker: number): void;
    /**
     * 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
     * {@link IntStream initializing method} has occurred after this stream was
     * constructed.
     */
    readonly index: number;
    /**
     * 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 {@link #EOF}
     *
     * This operation is guaranteed to not throw an exception if `index`
     * lies within a marked region. For more information on marked regions, see
     * {@link #mark}. The behavior of this method is unspecified if no call to
     * an {@link IntStream initializing method} has occurred after this stream
     * was constructed.
     *
     * @param index The absolute index to seek to.
     *
     * @throws IllegalArgumentException if `index` is less than 0
     * @throws UnsupportedOperationException if the stream does not support
     * seeking to the specified index
     */
    seek(index: number): void;
    /**
     * Returns the total number of symbols in the stream, including a single EOF
     * symbol.
     *
     * @throws UnsupportedOperationException if the size of the stream is
     * unknown.
     */
    readonly size: number;
    /**
     * Gets the name of the underlying symbol source. This method returns a
     * non-undefined, non-empty string. If such a name is not known, this method
     * returns {@link #UNKNOWN_SOURCE_NAME}.
     */
    readonly sourceName: string;
}