1 | /*
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2 | * Copyright 2002-2004 The Apache Software Foundation
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | */
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17 | package org.apache.tools.ant.filters;
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18 |
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19 | import java.io.IOException;
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20 | import java.io.Reader;
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21 |
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22 | /**
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23 | * This is a Java comment and string stripper reader that filters
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24 | * those lexical tokens out for purposes of simple Java parsing.
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25 | * (if you have more complex Java parsing needs, use a real lexer).
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26 | * Since this class heavily relies on the single char read function,
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27 | * you are recommended to make it work on top of a buffered reader.
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28 | *
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29 | */
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30 | public final class StripJavaComments
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31 | extends BaseFilterReader
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32 | implements ChainableReader {
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33 |
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34 | /**
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35 | * The read-ahead character, used for effectively pushing a single
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36 | * character back. A value of -1 indicates that no character is in the
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37 | * buffer.
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38 | */
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39 | private int readAheadCh = -1;
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40 |
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41 | /**
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42 | * Whether or not the parser is currently in the middle of a string
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43 | * literal.
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44 | */
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45 | private boolean inString = false;
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46 |
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47 | /**
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48 | * Whether or not the last char has been a backslash.
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49 | */
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50 | private boolean quoted = false;
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51 |
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52 | /**
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53 | * Constructor for "dummy" instances.
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54 | *
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55 | * @see BaseFilterReader#BaseFilterReader()
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56 | */
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57 | public StripJavaComments() {
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58 | super();
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59 | }
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60 |
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61 | /**
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62 | * Creates a new filtered reader.
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63 | *
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64 | * @param in A Reader object providing the underlying stream.
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65 | * Must not be <code>null</code>.
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66 | */
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67 | public StripJavaComments(final Reader in) {
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68 | super(in);
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69 | }
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70 |
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71 | /**
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72 | * Returns the next character in the filtered stream, not including
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73 | * Java comments.
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74 | *
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75 | * @return the next character in the resulting stream, or -1
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76 | * if the end of the resulting stream has been reached
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77 | *
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78 | * @exception IOException if the underlying stream throws an IOException
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79 | * during reading
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80 | */
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81 | public final int read() throws IOException {
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82 | int ch = -1;
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83 | if (readAheadCh != -1) {
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84 | ch = readAheadCh;
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85 | readAheadCh = -1;
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86 | } else {
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87 | ch = in.read();
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88 | if (ch == '"' && !quoted) {
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89 | inString = !inString;
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90 | quoted = false;
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91 | } else if (ch == '\\') {
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92 | quoted = !quoted;
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93 | } else {
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94 | quoted = false;
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95 | if (!inString) {
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96 | if (ch == '/') {
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97 | ch = in.read();
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98 | if (ch == '/') {
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99 | while (ch != '\n' && ch != -1 && ch != '\r') {
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100 | ch = in.read();
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101 | }
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102 | } else if (ch == '*') {
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103 | while (ch != -1) {
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104 | ch = in.read();
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105 | if (ch == '*') {
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106 | ch = in.read();
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107 | while (ch == '*' && ch != -1) {
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108 | ch = in.read();
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109 | }
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110 |
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111 | if (ch == '/') {
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112 | ch = read();
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113 | break;
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114 | }
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115 | }
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116 | }
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117 | } else {
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118 | readAheadCh = ch;
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119 | ch = '/';
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120 | }
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121 | }
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122 | }
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123 | }
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124 | }
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125 |
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126 | return ch;
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127 | }
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128 |
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129 | /**
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130 | * Creates a new StripJavaComments using the passed in
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131 | * Reader for instantiation.
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132 | *
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133 | * @param rdr A Reader object providing the underlying stream.
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134 | * Must not be <code>null</code>.
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135 | *
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136 | * @return a new filter based on this configuration, but filtering
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137 | * the specified reader
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138 | */
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139 |
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140 | public final Reader chain(final Reader rdr) {
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141 | StripJavaComments newFilter = new StripJavaComments(rdr);
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142 | return newFilter;
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143 | }
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144 | }
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