1 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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2 | * JFlex 1.4.3 *
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3 | * Copyright (C) 1998-2009 Gerwin Klein <[email protected]> *
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4 | * All rights reserved. *
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5 | * *
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6 | * This program is free software; you can redistribute it and/or modify *
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7 | * it under the terms of the GNU General Public License. See the file *
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8 | * COPYRIGHT for more information. *
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9 | * *
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10 | * This program is distributed in the hope that it will be useful, *
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of *
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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13 | * GNU General Public License for more details. *
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14 | * *
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15 | * You should have received a copy of the GNU General Public License along *
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16 | * with this program; if not, write to the Free Software Foundation, Inc., *
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17 | * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *
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18 | * *
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19 | * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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20 |
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21 | package JFlex;
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22 |
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23 | import java.util.*;
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24 |
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25 |
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26 | /**
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27 | * Symbol table and expander for macros.
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28 | *
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29 | * Maps macros to their (expanded) definitions, detects cycles and
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30 | * unused macros.
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31 | *
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32 | * @author Gerwin Klein
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33 | * @version JFlex 1.4.3, $Revision: 433 $, $Date: 2009-01-31 19:52:34 +1100 (Sat, 31 Jan 2009) $
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34 | */
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35 | final public class Macros {
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36 |
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37 | /** Maps names of macros to their definition */
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38 | private Hashtable macros;
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39 |
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40 | /** Maps names of macros to their "used" flag */
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41 | private Hashtable used;
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42 |
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43 |
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44 | /**
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45 | * Creates a new macro expander.
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46 | */
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47 | public Macros() {
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48 | macros = new Hashtable();
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49 | used = new Hashtable();
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50 | }
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51 |
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52 |
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53 | /**
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54 | * Stores a new macro and its definition.
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55 | *
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56 | * @param name the name of the new macro
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57 | * @param definition the definition of the new macro
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58 | *
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59 | * @return <code>true</code>, iff the macro name has not been
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60 | * stored before.
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61 | */
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62 | public boolean insert(String name, RegExp definition) {
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63 |
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64 | if (Options.DEBUG)
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65 | Out.debug("inserting macro "+name+" with definition :"+Out.NL+definition); //$NON-NLS-1$ //$NON-NLS-2$
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66 |
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67 | used.put(name, Boolean.FALSE);
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68 | return macros.put(name,definition) == null;
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69 | }
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70 |
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71 |
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72 | /**
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73 | * Marks a makro as used.
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74 | *
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75 | * @return <code>true</code>, iff the macro name has been
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76 | * stored before.
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77 | */
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78 | public boolean markUsed(String name) {
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79 | return used.put(name, Boolean.TRUE) != null;
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80 | }
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81 |
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82 |
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83 | /**
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84 | * Tests if a macro has been used.
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85 | *
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86 | * @return <code>true</code>, iff the macro has been used in
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87 | * a regular expression.
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88 | */
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89 | public boolean isUsed(String name) {
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90 | return ((Boolean)used.get(name)).booleanValue();
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91 | }
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92 |
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93 |
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94 | /**
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95 | * Returns all unused macros.
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96 | *
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97 | * @return the enumeration of macro names that have not been used.
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98 | */
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99 | public Enumeration unused() {
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100 |
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101 | Vector unUsed = new Vector();
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102 |
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103 | Enumeration names = used.keys();
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104 | while ( names.hasMoreElements() ) {
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105 | String name = (String) names.nextElement();
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106 | Boolean isUsed = (Boolean) used.get( name );
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107 | if ( !isUsed.booleanValue() ) unUsed.addElement(name);
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108 | }
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109 |
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110 | return unUsed.elements();
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111 | }
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112 |
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113 |
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114 | /**
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115 | * Fetches the definition of the macro with the specified name,
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116 | * <p>
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117 | * The definition will either be the same as stored (expand() not
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118 | * called), or an equivalent one, that doesn't contain any macro
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119 | * usages (expand() called before).
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120 | *
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121 | * @param name the name of the macro
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122 | *
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123 | * @return the definition of the macro, <code>null</code> if
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124 | * no macro with the specified name has been stored.
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125 | *
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126 | * @see JFlex.Macros#expand
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127 | */
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128 | public RegExp getDefinition(String name) {
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129 | return (RegExp) macros.get(name);
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130 | }
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131 |
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132 |
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133 | /**
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134 | * Expands all stored macros, so that getDefinition always returns
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135 | * a defintion that doesn't contain any macro usages.
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136 | *
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137 | * @throws MacroException if there is a cycle in the macro usage graph.
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138 | */
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139 | public void expand() throws MacroException {
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140 |
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141 | Enumeration names;
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142 |
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143 | names = macros.keys();
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144 |
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145 | while ( names.hasMoreElements() ) {
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146 | String name = (String) names.nextElement();
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147 | if ( isUsed(name) )
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148 | macros.put(name, expandMacro(name, getDefinition(name)));
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149 | // this put doesn't get a new key, so only a new value
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150 | // is set for the key "name" (without changing the enumeration
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151 | // "names"!)
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152 | }
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153 | }
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154 |
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155 |
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156 | /**
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157 | * Expands the specified macro by replacing each macro usage
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158 | * with the stored definition.
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159 | *
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160 | * @param name the name of the macro to expand (for detecting cycles)
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161 | * @param definition the definition of the macro to expand
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162 | *
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163 | * @return the expanded definition of the macro.
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164 | *
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165 | * @throws MacroException when an error (such as a cyclic definition)
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166 | * occurs during expansion
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167 | */
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168 | private RegExp expandMacro(String name, RegExp definition) throws MacroException {
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169 |
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170 | // Out.print("checking macro "+name);
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171 | // Out.print("definition is "+definition);
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172 |
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173 | switch ( definition.type ) {
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174 | case sym.BAR:
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175 | case sym.CONCAT:
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176 | RegExp2 binary = (RegExp2) definition;
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177 | binary.r1 = expandMacro(name, binary.r1);
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178 | binary.r2 = expandMacro(name, binary.r2);
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179 | return definition;
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180 |
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181 | case sym.STAR:
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182 | case sym.PLUS:
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183 | case sym.QUESTION:
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184 | case sym.BANG:
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185 | case sym.TILDE:
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186 | RegExp1 unary = (RegExp1) definition;
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187 | unary.content = expandMacro(name, (RegExp) unary.content);
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188 | return definition;
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189 |
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190 | case sym.MACROUSE:
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191 | String usename = (String) ((RegExp1) definition).content;
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192 |
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193 | if ( name.equals(usename) )
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194 | throw new MacroException(ErrorMessages.get(ErrorMessages.MACRO_CYCLE, name));
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195 |
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196 | RegExp usedef = getDefinition(usename);
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197 |
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198 | if ( usedef == null )
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199 | throw new MacroException(ErrorMessages.get(ErrorMessages.MACRO_DEF_MISSING, usename, name));
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200 |
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201 | markUsed(usename);
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202 |
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203 | return expandMacro(name, usedef);
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204 |
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205 | case sym.STRING:
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206 | case sym.STRING_I:
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207 | case sym.CHAR:
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208 | case sym.CHAR_I:
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209 | case sym.CCLASS:
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210 | case sym.CCLASSNOT:
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211 | return definition;
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212 |
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213 | default:
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214 | throw new MacroException("unknown expression type "+definition.type+" in macro expansion"); //$NON-NLS-1$ //$NON-NLS-2$
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215 | }
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216 | }
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217 | }
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