| 1 | /* This file is part of the project "Hilbert II" - http://www.qedeq.org |
| 2 | * |
| 3 | * Copyright 2000-2014, Michael Meyling <mime@qedeq.org>. |
| 4 | * |
| 5 | * "Hilbert II" is free software; you can redistribute |
| 6 | * it and/or modify it under the terms of the GNU General Public |
| 7 | * License as published by the Free Software Foundation; either |
| 8 | * version 2 of the License, or (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | */ |
| 15 | |
| 16 | package org.qedeq.kernel.bo.parser; |
| 17 | |
| 18 | import java.util.Stack; |
| 19 | |
| 20 | import org.qedeq.base.io.TextInput; |
| 21 | |
| 22 | /** |
| 23 | * Remember TextInput positions. |
| 24 | * |
| 25 | * @author Michael Meyling |
| 26 | */ |
| 27 | public class MementoTextInput { |
| 28 | |
| 29 | /** For remembering input positions. */ |
| 30 | private final Stack stack = new Stack(); |
| 31 | |
| 32 | /** Input source to parse. */ |
| 33 | private final TextInput input; |
| 34 | |
| 35 | /** |
| 36 | * Constructor. |
| 37 | * |
| 38 | * @param input Input source to parse. |
| 39 | */ |
| 40 | public MementoTextInput(final TextInput input) { |
| 41 | this.input = input; |
| 42 | } |
| 43 | |
| 44 | /** |
| 45 | * Remember current position. |
| 46 | */ |
| 47 | public void markPosition() { |
| 48 | stack.push(new Integer(input.getPosition())); |
| 49 | } |
| 50 | |
| 51 | /** |
| 52 | * Rewind to previous marked position. Also clears the mark. |
| 53 | * |
| 54 | * @return Current position before pop. |
| 55 | */ |
| 56 | public long rewindPosition() { |
| 57 | final long oldPosition = getPosition(); |
| 58 | input.setPosition(((Integer) stack.pop()).intValue()); |
| 59 | return oldPosition; |
| 60 | } |
| 61 | |
| 62 | /** |
| 63 | * Forget last remembered position. |
| 64 | */ |
| 65 | public void clearMark() { |
| 66 | stack.pop(); |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Get byte position. |
| 71 | * |
| 72 | * @return Position. |
| 73 | */ |
| 74 | public long getPosition() { |
| 75 | return input.getPosition(); |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Reads a single character and does not change the reading |
| 80 | * position. |
| 81 | * |
| 82 | * @return character read, if there are no more chars |
| 83 | * <code>-1</code> is returned |
| 84 | */ |
| 85 | public int getChar() { |
| 86 | return input.getChar(); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * Reads a single character and increments the reading position |
| 91 | * by one. |
| 92 | * |
| 93 | * @return character read, if there are no more chars |
| 94 | * <code>-1</code> is returned |
| 95 | */ |
| 96 | public int read() { |
| 97 | return input.read(); |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * Are there still any characters to read? |
| 102 | * |
| 103 | * @return Anything left for reading further? |
| 104 | */ |
| 105 | public final boolean isEmpty() { |
| 106 | return input.isEmpty(); |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * Get rewind stack size. |
| 111 | * |
| 112 | * @return Rewind stack size. |
| 113 | */ |
| 114 | public int getRewindStackSize() { |
| 115 | return stack.size(); |
| 116 | } |
| 117 | |
| 118 | /** |
| 119 | * Returns the current column number. |
| 120 | * |
| 121 | * @return Current column number (starting with line 1). |
| 122 | */ |
| 123 | public int getColumn() { |
| 124 | return input.getColumn(); |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * Returns the current line number. |
| 129 | * |
| 130 | * @return Current line number (starting with line 1). |
| 131 | */ |
| 132 | public int getRow() { |
| 133 | return input.getRow(); |
| 134 | } |
| 135 | |
| 136 | /** |
| 137 | * Returns the current line. |
| 138 | * |
| 139 | * @return Current line. |
| 140 | */ |
| 141 | public String getLine() { |
| 142 | return input.getLine(); |
| 143 | } |
| 144 | |
| 145 | /** |
| 146 | * Decrements the reading position by one and reads a single character. |
| 147 | * If no characters are left, <code>-1</code> is returned. |
| 148 | * Otherwise a cast to <code>char</code> gives the character read. |
| 149 | * |
| 150 | * @return Character read, if there are no more chars |
| 151 | * <code>-1</code> is returned. |
| 152 | */ |
| 153 | public int readInverse() { |
| 154 | return input.readInverse(); |
| 155 | } |
| 156 | |
| 157 | } |