git.gag.com Git - debian/openrocket/blob - core/src/de/congrace/exp4j/Tokenizer.java

   1 /*
   2    Copyright 2011 frank asseg
   3
   4    Licensed under the Apache License, Version 2.0 (the "License");
   5    you may not use this file except in compliance with the License.
   6    You may obtain a copy of the License at
   7
   8        http://www.apache.org/licenses/LICENSE-2.0
   9
  10    Unless required by applicable law or agreed to in writing, software
  11    distributed under the License is distributed on an "AS IS" BASIS,
  12    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13    See the License for the specific language governing permissions and
  14    limitations under the License.
  15
  16  */
  17 package de.congrace.exp4j;
  18
  19 import java.util.ArrayList;
  20 import java.util.HashSet;
  21 import java.util.List;
  22 import java.util.Set;
  23
  24 import de.congrace.exp4j.FunctionToken.Function;
  25
  26 /**
  27  * Class for tokenizing mathematical expressions by breaking an expression up
  28  * into multiple different {@link Token}s
  29  *
  30  * @author fas@congrace.de
  31  */
  32 class Tokenizer {
  33         private String[] variableNames;
  34         private final Set<String> functionNames = new HashSet<String>();
  35         private final Set<CustomFunction> customFunctions;
  36
  37         {
  38                 functionNames.add("abs");
  39                 functionNames.add("acos");
  40                 functionNames.add("asin");
  41                 functionNames.add("atan");
  42                 functionNames.add("cbrt");
  43                 functionNames.add("ceil");
  44                 functionNames.add("cos");
  45                 functionNames.add("cosh");
  46                 functionNames.add("exp");
  47                 functionNames.add("expm1");
  48                 functionNames.add("floor");
  49                 functionNames.add("log");
  50                 functionNames.add("sin");
  51                 functionNames.add("sinh");
  52                 functionNames.add("sqrt");
  53                 functionNames.add("tan");
  54                 functionNames.add("tanh");
  55         }
  56
  57         Tokenizer() {
  58                 super();
  59                 customFunctions = null;
  60         }
  61
  62         /**
  63          * construct a new Tokenizer that recognizes variable names
  64          *
  65          * @param variableNames
  66          *            the variable names in the expression
  67          * @throws IllegalArgumentException
  68          *             if a variable has the name as a function
  69          * @param customFunctions
  70          *            the CustomFunction implementations used if the variableNames
  71          *            are not valid
  72          */
  73         Tokenizer(String[] variableNames, Set<CustomFunction> customFunctions) throws IllegalArgumentException {
  74                 super();
  75                 this.variableNames = variableNames;
  76
  77                 if (variableNames != null) {
  78                         for (String varName : variableNames) {
  79                                 if (functionNames.contains(varName.toLowerCase())) {
  80                                         throw new IllegalArgumentException("Variable '" + varName + "' can not have the same name as a function");
  81                                 }
  82                         }
  83                 }
  84                 this.customFunctions = customFunctions;
  85         }
  86
  87         private Token getCustomFunctionToken(String name) throws UnknownFunctionException {
  88                 for (CustomFunction func : customFunctions) {
  89                         if (func.getValue().equals(name)) {
  90                                 return func;
  91                         }
  92                 }
  93                 throw new UnknownFunctionException(name);
  94         }
  95
  96         private boolean isCustomFunction(String name) {
  97                 if (customFunctions == null) {
  98                         return false;
  99                 }
 100                 for (CustomFunction func : customFunctions) {
 101                         if (func.getValue().equals(name)) {
 102                                 return true;
 103                         }
 104                 }
 105                 return false;
 106         }
 107
 108         /**
 109          * check if a char is part of a number
 110          *
 111          * @param c
 112          *            the char to be checked
 113          * @return true if the char is part of a number
 114          */
 115         private boolean isDigit(char c) {
 116                 return Character.isDigit(c) || c == '.';
 117         }
 118
 119         private boolean isFunction(String name) {
 120                 for (Function fn : Function.values()) {
 121                         if (fn.name().equals(name.toUpperCase())) {
 122                                 return true;
 123                         }
 124                 }
 125                 return false;
 126         }
 127
 128         /**
 129          * check if a String is a variable name
 130          *
 131          * @param name
 132          *            the variable name which is checked to be valid the char to be
 133          *            checked
 134          * @return true if the char is a variable name (e.g. x)
 135          */
 136         private boolean isVariable(String name) {
 137                 //String[] variableNames = variables.getVariableNames();
 138
 139                 if (variableNames != null) {
 140                         for (String var : variableNames) {
 141                                 if (name.equals(var)) {
 142                                         return true;
 143                                 }
 144                         }
 145                 }
 146                 return false;
 147         }
 148
 149         /**
 150          * tokenize an infix expression by breaking it up into different
 151          * {@link Token} that can represent operations,functions,numbers,
 152          * parenthesis or variables
 153          *
 154          * @param infix
 155          *            the infix expression to be tokenized
 156          * @return the {@link Token}s representing the expression
 157          * @throws UnparsableExpressionException
 158          *             when the expression is invalid
 159          * @throws UnknownFunctionException
 160          *             when an unknown function name has been used.
 161          */
 162         Token[] tokenize(String infix) throws UnparsableExpressionException, UnknownFunctionException {
 163                 final List<Token> tokens = new ArrayList<Token>();
 164                 final char[] chars = infix.toCharArray();
 165                 // iterate over the chars and fork on different types of input
 166                 Token lastToken;
 167                 for (int i = 0; i < chars.length; i++) {
 168                         char c = chars[i];
 169
 170                         if (c == ' ')
 171                                 continue;
 172                         if (isDigit(c)) {
 173                                 final StringBuilder valueBuilder = new StringBuilder(1);
 174                                 // handle the numbers of the expression
 175                                 valueBuilder.append(c);
 176                                 int numberLen = 1;
 177                                 while (chars.length > i + numberLen && isDigit(chars[i + numberLen])) {
 178                                         valueBuilder.append(chars[i + numberLen]);
 179                                         numberLen++;
 180                                 }
 181                                 i += numberLen - 1;
 182                                 lastToken = new NumberToken(valueBuilder.toString());
 183                         } else if (Character.isLetter(c) || c == '_' || c == '$') {
 184                                 // can be a variable or function
 185                                 final StringBuilder nameBuilder = new StringBuilder();
 186                                 nameBuilder.append(c);
 187                                 int offset = 1;
 188                                 while (chars.length > i + offset && (Character.isLetter(chars[i + offset]) || Character.isDigit(chars[i + offset]) || chars[i + offset] == '_' || chars[i + offset] == '$')) {
 189                                         nameBuilder.append(chars[i + offset++]);
 190                                 }
 191                                 String name = nameBuilder.toString();
 192                                 if (this.isVariable(name)) {
 193                                         // a variable
 194                                         i += offset - 1;
 195                                         lastToken = new VariableToken(name);
 196                                 } else if (this.isFunction(name)) {
 197                                         // might be a function
 198                                         i += offset - 1;
 199                                         lastToken = new FunctionToken(name);
 200                                 } else if (this.isCustomFunction(name)) {
 201                                         // a custom function
 202                                         i += offset - 1;
 203                                         lastToken = getCustomFunctionToken(name);
 204                                 } else {
 205                                         // an unknown symbol was encountered
 206                                         throw new UnparsableExpressionException(c, i);
 207                                 }
 208                         }else if (c == ',') {
 209                             // a function separator, hopefully
 210                             lastToken=new FunctionSeparatorToken();
 211                         } else if (OperatorToken.isOperator(c)) {
 212                                 lastToken = new OperatorToken(String.valueOf(c), OperatorToken.getOperation(c));
 213                         } else if (c == '(' || c == ')' || c == '[' || c == ']' || c == '{' || c == '}') {
 214                                 lastToken = new ParenthesisToken(String.valueOf(c));
 215                         } else {
 216                                 // an unknown symbol was encountered
 217                                 throw new UnparsableExpressionException(c, i);
 218                         }
 219                         tokens.add(lastToken);
 220                 }
 221                 return tokens.toArray(new Token[tokens.size()]);
 222         }
 223 }