/*
 * Copyright (c) 2012-2020 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

module antlr.v4.runtime.TokenStream;

import antlr.v4.runtime.IntStream;
import antlr.v4.runtime.Token;
import antlr.v4.runtime.TokenSource;
import antlr.v4.runtime.RuleContext;
import antlr.v4.runtime.misc.Interval;
import std.variant;

/**
 * This TokenStream uses the data type Variant for storing text.
 *
 * Therefore tabulator based syntax can be used more complex text elements,
 * i.e. text string in combination with number of tabs.
 */
interface TokenStream : IntStream
{

    /**
     * Get the {@link Token} instance associated with the value returned by
     * {@link #LA LA(k)}. This method has the same pre- and post-conditions as
     * {@link IntStream#LA}. In addition, when the preconditions of this method
     * are met, the return value is non-null and the value of
     * {@code LT(k).getType()==LA(k)}.
     *
     *  @see IntStream#LA
     */
    public Token LT(int k);

    /**
     * Gets the {@link Token} at the specified {@code index} in the stream. When
     * the preconditions of this method are met, the return value is non-null.
     *
     * <p>The preconditions for this method are the same as the preconditions of
     * {@link IntStream#seek}. If the behavior of {@code seek(index)} is
     * unspecified for the current state and given {@code index}, then the
     * behavior of this method is also unspecified.</p>
     *
     * <p>The symbol referred to by {@code index} differs from {@code seek()} only
     * in the case of filtering streams where {@code index} lies before the end
     * of the stream. Unlike {@code seek()}, this method does not adjust
     * {@code index} to point to a non-ignored symbol.</p>
     *
     * Throws:
     * - IllegalArgumentException if {code index} is less than 0<br>
     * - UnsupportedOperationException if the stream does not support
     *  retrieving the token at the specified index
     */
    public Token get(size_t index);

    /**
     * Gets the underlying {@link TokenSource} which provides tokens for this
     * stream.
     */
    public TokenSource getTokenSource();

    /**
     * Return the text of all tokens within the specified {@code interval}. This
     * method behaves like the following code (including potential exceptions)
     * for violating preconditions of {@link #get}, but may be optimized by the
     * specific implementation.
     *
     * <pre>
     * TokenStream stream = ...;
     * String text = "";
     * for (int i = interval.a; i &lt;= interval.b; i++) {
     *   text += stream.get(i).getText();
     * }
     * </pre>
     *
     *  @param interval The interval of tokens within this stream to get text
     * for.
     *  @return The text of all tokens within the specified interval in this
     * stream.
     *
     *  Throws:
     *  NullPointerException if {@code interval} is {@code null}
     */
    public Variant getText(Interval interval);

    /**
     * Return the text of all tokens in the stream. This method behaves like the
     * following code, including potential exceptions from the calls to
     * {@link IntStream#size} and {@link #getText(Interval)}, but may be
     * optimized by the specific implementation.
     *
     * <pre>
     * TokenStream stream = ...;
     * String text = stream.getText(new Interval(0, stream.size()));
     * </pre>
     *
     *  @return The text of all tokens in the stream.
     */
    public Variant getText();

    /**
     * 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 {@link #getText(Interval)}, but may be
     * optimized by the specific implementation.
     *
     * <p>If {@code ctx.getSourceInterval()} does not return a valid interval of
     * tokens provided by this stream, the behavior is unspecified.</p>
     *
     * <pre>
     * TokenStream stream = ...;
     * String text = stream.getText(ctx.getSourceInterval());
     * </pre>
     *
     *  @param ctx The context providing the source interval of tokens to get
     *  text for.
     *  @return The text of all tokens within the source interval of {@code ctx}.
     */
    public Variant getText(RuleContext ctx);

    /**
     * Return the text of all tokens in this stream between {@code start} and
     * {@code stop} (inclusive).
     *
     * <p>If the specified {@code start} or {@code stop} token was not provided by
     * this stream, or if the {@code stop} occurred before the {@code start}
     * token, the behavior is unspecified.</p>
     *
     * <p>For streams which ensure that the {@link 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.</p>
     *
     * <pre>
     * TokenStream stream = ...;
     * String text = "";
     * for (int i = start.getTokenIndex(); i &lt;= stop.getTokenIndex(); i++) {
     *   text += stream.get(i).getText();
     * }
     * </pre>
     *
     *  @param start The first token in the interval to get text for.
     *  @param stop The last token in the interval to get text for (inclusive).
     *  @return The text of all tokens lying between the specified {@code start}
     *  and {@code stop} tokens.
     *
     *  @throws UnsupportedOperationException if this stream does not support
     *  this method for the specified tokens
     */
    public Variant getText(Token start, Token stop);

}