antlr.v4.runtime.atn.LexerAction source code

1 /*
2  * Copyright (c) 2012-2018 The ANTLR Project. All rights reserved.
3  * Use of this file is governed by the BSD 3-clause license that
4  * can be found in the LICENSE.txt file in the project root.
5  */
6 
7 module antlr.v4.runtime.atn.LexerAction;
8 
9 import antlr.v4.runtime.InterfaceLexer;
10 import antlr.v4.runtime.atn.LexerActionType;
11 
12 /**
13  * Represents a single action which can be executed following the successful
14  * match of a lexer rule. Lexer actions are used for both embedded action syntax
15  * and ANTLR 4's new lexer command syntax.
16  */
17 interface LexerAction
18 {
19 
20     /**
21      * Gets the serialization type of the lexer action.
22      *
23      *  @return The serialization type of the lexer action.
24      */
25     public LexerActionType getActionType();
26 
27     /**
28      * Gets whether the lexer action is position-dependent. Position-dependent
29      * actions may have different semantics depending on the {@link CharStream}
30      * index at the time the action is executed.
31      *
32      * <p>Many lexer commands, including {@code type}, {@code skip}, and
33      * {@code more}, do not check the input index during their execution.
34      * Actions like this are position-independent, and may be stored more
35      * efficiently as part of the {@link LexerATNConfig#lexerActionExecutor}.</p>
36      *
37      *  @return {@code true} if the lexer action semantics can be affected by the
38      * position of the input {@link CharStream} at the time it is executed;
39      * otherwise, {@code false}.
40      */
41     public bool isPositionDependent();
42 
43     /**
44      * Execute the lexer action in the context of the specified {@link Lexer}.
45      *
46      * <p>For position-dependent actions, the input stream must already be
47      * positioned correctly prior to calling this method.</p>
48      *
49      *  @param lexer The lexer instance.
50      */
51     public void execute(InterfaceLexer lexer);
52 
53     /**
54      * @uml
55      * @nothrow
56      */
57     public size_t toHash() nothrow;
58 
59 }