1/* 2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package com.sun.tools.javac.parser; 27 28import java.nio.*; 29import java.util.List; 30import java.util.ArrayList; 31 32import com.sun.tools.javac.util.Position.LineMap; 33import com.sun.tools.javac.parser.JavaTokenizer.*; 34 35import static com.sun.tools.javac.parser.Tokens.*; 36 37/** The lexical analyzer maps an input stream consisting of 38 * ASCII characters and Unicode escapes into a token sequence. 39 * 40 * <p><b>This is NOT part of any supported API. 41 * If you write code that depends on this, you do so at your own risk. 42 * This code and its internal interfaces are subject to change or 43 * deletion without notice.</b> 44 */ 45public class Scanner implements Lexer { 46 47 private Tokens tokens; 48 49 /** The token, set by nextToken(). 50 */ 51 private Token token; 52 53 /** The previous token, set by nextToken(). 54 */ 55 private Token prevToken; 56 57 /** Buffer of saved tokens (used during lookahead) 58 */ 59 private List<Token> savedTokens = new ArrayList<>(); 60 61 private JavaTokenizer tokenizer; 62 63 /** 64 * Create a scanner from the input array. This method might 65 * modify the array. To avoid copying the input array, ensure 66 * that {@code inputLength < input.length} or 67 * {@code input[input.length -1]} is a white space character. 68 * 69 * @param fac the factory which created this Scanner 70 * @param buf the input, might be modified 71 * Must be positive and less than or equal to input.length. 72 */ 73 protected Scanner(ScannerFactory fac, CharBuffer buf) { 74 this(fac, new JavaTokenizer(fac, buf)); 75 } 76 77 protected Scanner(ScannerFactory fac, char[] buf, int inputLength) { 78 this(fac, new JavaTokenizer(fac, buf, inputLength)); 79 } 80 81 protected Scanner(ScannerFactory fac, JavaTokenizer tokenizer) { 82 this.tokenizer = tokenizer; 83 tokens = fac.tokens; 84 token = prevToken = DUMMY; 85 } 86 87 public Token token() { 88 return token(0); 89 } 90 91 public Token token(int lookahead) { 92 if (lookahead == 0) { 93 return token; 94 } else { 95 ensureLookahead(lookahead); 96 return savedTokens.get(lookahead - 1); 97 } 98 } 99 //where 100 private void ensureLookahead(int lookahead) { 101 for (int i = savedTokens.size() ; i < lookahead ; i ++) { 102 savedTokens.add(tokenizer.readToken()); 103 } 104 } 105 106 public Token prevToken() { 107 return prevToken; 108 } 109 110 public void nextToken() { 111 prevToken = token; 112 if (!savedTokens.isEmpty()) { 113 token = savedTokens.remove(0); 114 } else { 115 token = tokenizer.readToken(); 116 } 117 } 118 119 public Token split() { 120 Token[] splitTokens = token.split(tokens); 121 prevToken = splitTokens[0]; 122 token = splitTokens[1]; 123 return token; 124 } 125 126 public LineMap getLineMap() { 127 return tokenizer.getLineMap(); 128 } 129 130 public int errPos() { 131 return tokenizer.errPos(); 132 } 133 134 public void errPos(int pos) { 135 tokenizer.errPos(pos); 136 } 137} 138