diff --git a/android/.classpath b/android/.classpath index 4620a5b3e..07677d89f 100644 --- a/android/.classpath +++ b/android/.classpath @@ -7,6 +7,5 @@ - diff --git a/android/libs/exp4j-rdg.jar b/android/libs/exp4j-rdg.jar deleted file mode 100644 index 8a980164b..000000000 Binary files a/android/libs/exp4j-rdg.jar and /dev/null differ diff --git a/core/.classpath b/core/.classpath index fd1223fb1..fb297f54e 100644 --- a/core/.classpath +++ b/core/.classpath @@ -30,6 +30,5 @@ - diff --git a/core/build.xml b/core/build.xml index 11f2fc352..9b178defe 100644 --- a/core/build.xml +++ b/core/build.xml @@ -112,7 +112,6 @@ - diff --git a/core/src/de/congrace/exp4j/AbstractExpression.java b/core/src/de/congrace/exp4j/AbstractExpression.java new file mode 100644 index 000000000..fc7f56b80 --- /dev/null +++ b/core/src/de/congrace/exp4j/AbstractExpression.java @@ -0,0 +1,77 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.text.NumberFormat; +import java.util.ArrayList; +import java.util.List; + +/** + * Abstract base class for mathematical expressions + * + * @author fas@congrace.de + */ +abstract class AbstractExpression { + private final String expression; + private final Token[] tokens; + private final String[] variableStrings; + private final NumberFormat numberFormat = NumberFormat.getInstance(); + + /** + * Construct a new {@link AbstractExpression} + * + * @param expression + * the mathematical expression to be used + * @param tokens + * the {@link Token}s in the expression + * @param variableNames + * an array of variable names which are used in the expression + */ + AbstractExpression(String expression, Token[] tokens, String[] variableStrings) { + this.expression = expression; + this.tokens = tokens; + this.variableStrings = variableStrings; + } + + /** + * get the mathematical expression {@link String} + * + * @return the expression + */ + public String getExpression() { + return expression; + } + + /** + * get the used {@link NumberFormat} + * + * @return the used {@link NumberFormat} + */ + public NumberFormat getNumberFormat() { + return numberFormat; + } + + /** + * get the {@link Token}s + * + * @return the array of {@link Token}s + */ + Token[] getTokens() { + return tokens; + } + +} diff --git a/core/src/de/congrace/exp4j/Calculable.java b/core/src/de/congrace/exp4j/Calculable.java new file mode 100644 index 000000000..4009cb5d7 --- /dev/null +++ b/core/src/de/congrace/exp4j/Calculable.java @@ -0,0 +1,31 @@ +package de.congrace.exp4j; + +/** + * This is the basic result class of the exp4j {@link ExpressionBuilder} + * + * @author ruckus + * + */ +public interface Calculable { + /** + * calculate the result of the expression + * + * @return the result of the calculation + */ + public Variable calculate(); + + /** + * return the expression in reverse polish postfix notation + * + * @return the expression used to construct this {@link Calculable} + */ + public String getExpression(); + + /** + * set a variable value for the calculation + * + * @param value + * the value of the variable + */ + public void setVariable(Variable var); +} diff --git a/core/src/de/congrace/exp4j/CalculationToken.java b/core/src/de/congrace/exp4j/CalculationToken.java new file mode 100644 index 000000000..c40408aa5 --- /dev/null +++ b/core/src/de/congrace/exp4j/CalculationToken.java @@ -0,0 +1,76 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Arrays; +import java.util.Stack; + +abstract class CalculationToken extends Token { + + CalculationToken(String value) { + super(value); + } + + abstract void mutateStackForCalculation(Stack stack, VariableSet variables); + + /* + * Given an array of variables, check if any are arrays and if so expand any other of the given variables to arrays of the same length. + * Doubles are turned into arrays of all the same value as original. Arrays of other lengths are padded with zeros. + */ + public Variable[] expandVariables(Variable[] values){ + // Check if any variables have preferred representation as arrays + int maxLength = 0; + for (Variable v : values){ + if (v.getPrimary() == Variable.Primary.ARRAY && v.getArrayValue().length > maxLength){ + maxLength = v.getArrayValue().length; + } + } + + // if necessary, expand any non-array variables to maximum length + if (maxLength > 0) { + for (int n = 0; n + * java de.congrace.exp4j.CommandlineInterpreter "2 * log(2.2223) - ((2-3.221) * 14.232^2)" + * > 248.91042049521056 + * + * + * @author fas@congrace.de + * + */ +public class CommandlineInterpreter { + private static void calculateExpression(String string) { + try { + final PostfixExpression pe = PostfixExpression.fromInfix(string); + System.out.println(pe.calculate()); + } catch (UnparsableExpressionException e) { + e.printStackTrace(); + } catch (UnknownFunctionException e) { + e.printStackTrace(); + } + } + + public static void main(String[] args) { + if (args.length != 1) { + printUsage(); + } else { + calculateExpression(args[0]); + } + } + + private static void printUsage() { + final StringBuilder usage = new StringBuilder(); + usage.append("Commandline Expression Parser\n\n").append("Example: ").append("\n").append("java -jar exp4j.jar \"2.12 * log(23) * (12 - 4)\"\n\n") + .append("written by fas@congrace.de"); + System.err.println(usage.toString()); + } +} diff --git a/core/src/de/congrace/exp4j/CustomFunction.java b/core/src/de/congrace/exp4j/CustomFunction.java new file mode 100644 index 000000000..f49f94815 --- /dev/null +++ b/core/src/de/congrace/exp4j/CustomFunction.java @@ -0,0 +1,90 @@ +package de.congrace.exp4j; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; +import java.util.Map; +import java.util.Stack; + +import de.congrace.exp4j.FunctionToken.Function; + +/** + * this classed is used to create custom functions for exp4j
+ *
+ * Example
+ * 
{@code 
+ * CustomFunction fooFunc = new CustomFunction("foo") {
+ * 		public double applyFunction(double value) {
+ * 			return value*Math.E;
+ * 		}
+ * };
+ * double varX=12d;
+ * Calculable calc = new ExpressionBuilder("foo(x)").withCustomFunction(fooFunc).withVariable("x",varX).build();
+ * assertTrue(calc.calculate() == Math.E * varX);
+ * }
 + * + * @author ruckus + * + */ +public abstract class CustomFunction extends CalculationToken { + private int argc=1; + + /** + * create a new single value input CustomFunction with a set name + * + * @param value + * the name of the function (e.g. foo) + */ + protected CustomFunction(String value) throws InvalidCustomFunctionException{ + super(value); + for (Function f:Function.values()) { + if (value.equalsIgnoreCase(f.toString())){ + throw new InvalidCustomFunctionException(value + " is already reserved as a function name"); + } + } + } + + /** + * create a new single value input CustomFunction with a set name + * + * @param value + * the name of the function (e.g. foo) + */ + protected CustomFunction(String value,int argumentCount) throws InvalidCustomFunctionException{ + super(value); + this.argc=argumentCount; + for (Function f:Function.values()) { + if (value.equalsIgnoreCase(f.toString())){ + throw new InvalidCustomFunctionException(value + " is already reserved as a function name"); + } + } + } + + /** + * apply the function to a value + * + * @param values + * the values to which the function should be applied. + * @return the function value + */ + public abstract Variable applyFunction(List vars); + + @Override + void mutateStackForCalculation(Stack stack, VariableSet variables) { + List args = new ArrayList(argc); + for (int i=0; i < argc; i++) { + args.add(i, stack.pop() ); + } + Collections.reverse(args); // Put elements in logical order + + stack.push(this.applyFunction(args)); + } + + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + operatorStack.push(this); + } + public int getArgumentCount() { + return argc; + } +} diff --git a/core/src/de/congrace/exp4j/Example.java b/core/src/de/congrace/exp4j/Example.java new file mode 100644 index 000000000..0d70b0b09 --- /dev/null +++ b/core/src/de/congrace/exp4j/Example.java @@ -0,0 +1,77 @@ +package de.congrace.exp4j; + +import java.util.List; + +public class Example { + + public static void main(String[] args) throws UnknownFunctionException, UnparsableExpressionException, InvalidCustomFunctionException { + + // Test 1 + // ====== + + Calculable calc1 = new ExpressionBuilder("x * y - 2").withVariableNames("x", "y").build(); + calc1.setVariable(new Variable("x", 1.2)); + calc1.setVariable(new Variable("y", 2.2)); + + System.out.println(calc1.calculate().toString()); + //double result = calc1.calculate().getDoubleValue(); + //System.out.println(result); + + // Test 2 + // ====== + + // A function which calculates the mean of an array and scales it + CustomFunction meanFn = new CustomFunction("mean",2) { + public Variable applyFunction(List vars) { + + double[] vals; + double scale; + + try{ + vals = vars.get(0).getArrayValue(); + scale = vars.get(1).getDoubleValue(); + } catch (Exception e) { + return new Variable("Invalid"); + } + + double subtotal = 0; + for (int i = 0; i < vals.length; i++ ){ + subtotal += vals[i]; + } + + subtotal = scale * subtotal / vals.length; + return new Variable("double MEAN result, ", subtotal); + + } + }; + + ExpressionBuilder b = new ExpressionBuilder("mean(x,y)"); + b.withCustomFunction(meanFn); + b.withVariable(new Variable("x", new double[] {1.1,2,10,3,2.4,10.2})); + b.withVariable(new Variable("y", 2)); + Calculable calc2 = b.build(); + + System.out.println( calc2.calculate().toString() ); + + // Test 3 + // ====== + + Calculable calc3 = new ExpressionBuilder("x * y - 2").withVariableNames("x", "y").build(); + calc3.setVariable(new Variable("x", new double[]{1.2, 10, 20, 15})); + calc3.setVariable(new Variable("y", new double[]{2.2, 5.2, 12, 9 })); + + //double result3 = calc3.calculate().getDoubleValue(); + System.out.println(calc3.calculate().toString()); + + + // Test 4 + // ====== + + Calculable calc4 = new ExpressionBuilder("log10(sqrt(x) * abs(y))").withVariableNames("x", "y").build(); + calc4.setVariable(new Variable("x", new double[]{1.2, 10, 10, 15})); + calc4.setVariable(new Variable("y", new double[]{2.2, -5.2, 5.2, 9 })); + + //double result3 = calc3.calculate().getDoubleValue(); + System.out.println(calc4.calculate().toString()); + } +} diff --git a/core/src/de/congrace/exp4j/ExpressionBuilder.java b/core/src/de/congrace/exp4j/ExpressionBuilder.java new file mode 100644 index 000000000..8ecf1b5cf --- /dev/null +++ b/core/src/de/congrace/exp4j/ExpressionBuilder.java @@ -0,0 +1,135 @@ +package de.congrace.exp4j; + +import java.util.Collection; +import java.util.HashSet; +import java.util.Set; + +/** + * This is Builder implementation for the exp4j API used to create a Calculable + * instance for the user + * + * @author ruckus + * + */ +public class ExpressionBuilder { + private VariableSet variables = new VariableSet(); + private final Set customFunctions = new HashSet(); + + private String expression; + + /** + * Create a new ExpressionBuilder + * + * @param expression + * the expression to evaluate + */ + public ExpressionBuilder(String expression) { + this.expression = expression; + } + + /** + * build a new {@link Calculable} from the expression using the supplied + * variables + * + * @return the {@link Calculable} which can be used to evaluate the + * expression + * @throws UnknownFunctionException + * when an unrecognized function name is used in the expression + * @throws UnparsableExpressionException + * if the expression could not be parsed + */ + public Calculable build() throws UnknownFunctionException, UnparsableExpressionException { + if (expression.indexOf('=') == -1 && !variables.isEmpty()) { + + // User supplied an expression without leading "f(...)=" + // so we just append the user function to a proper "f()=" + // for PostfixExpression.fromInfix() + StringBuilder function = new StringBuilder("f("); + for (String name : variables.getVariableNames()) { + function.append(name).append(','); + } + expression = function.deleteCharAt(function.length() - 1).toString() + ")=" + expression; + } + // create the PostfixExpression and return it as a Calculable + PostfixExpression delegate = PostfixExpression.fromInfix(expression, customFunctions); + for (Variable var : variables ) { + delegate.setVariable(var); + for (CustomFunction fn:customFunctions){ + if (fn.getValue().equalsIgnoreCase(var.getName())){ + throw new UnparsableExpressionException("variable '" + var + "' cannot have the same name as a custom function " + fn.getValue()); + } + } + } + return delegate; + } + + /** + * add a custom function instance for the evaluator to recognize + * + * @param function + * the {@link CustomFunction} to add + * @return the {@link ExpressionBuilder} instance + */ + public ExpressionBuilder withCustomFunction(CustomFunction function) { + customFunctions.add(function); + return this; + } + + public ExpressionBuilder withCustomFunctions(Collection functions) { + customFunctions.addAll(functions); + return this; + } + + /** + * set the value for a variable + * + * @param variableName + * the variable name e.g. "x" + * @param value + * the value e.g. 2.32d + * @return the {@link ExpressionBuilder} instance + */ + public ExpressionBuilder withVariable(Variable value) { + variables.add(value); + return this; + } + + /* + * Provided for backwards compatibility + */ + @Deprecated + public ExpressionBuilder withVariable(String variableName, double value) { + variables.add(new Variable(variableName, value)); + return this; + } + + /** + * set the variables names used in the expression without setting their + * values. Usefull for building an expression before you know the variable values. + * + * @param variableNames + * vararg {@link String} of the variable names used in the + * expression + * @return the ExpressionBuilder instance + */ + + public ExpressionBuilder withVariableNames(String... variableNames) { + for (String name : variableNames) { + variables.add( new Variable(name, Double.NaN) ); + } + return this; + } + + + /** + * set the values for variables + * + * @param variableMap + * a map of variable names to variable values + * @return the {@link ExpressionBuilder} instance + */ + public ExpressionBuilder withVariables(VariableSet variables) { + this.variables = variables; + return this; + } +} diff --git a/core/src/de/congrace/exp4j/FunctionSeparatorToken.java b/core/src/de/congrace/exp4j/FunctionSeparatorToken.java new file mode 100644 index 000000000..24b1109d4 --- /dev/null +++ b/core/src/de/congrace/exp4j/FunctionSeparatorToken.java @@ -0,0 +1,17 @@ +package de.congrace.exp4j; + +import java.util.Stack; + +public class FunctionSeparatorToken extends Token{ + public FunctionSeparatorToken() { + super(","); + } + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + Token token; + while (!((token=operatorStack.peek()) instanceof ParenthesisToken) && !token.getValue().equals("(")){ + output.append(operatorStack.pop().getValue()).append(" "); + } + } + +} diff --git a/core/src/de/congrace/exp4j/FunctionToken.java b/core/src/de/congrace/exp4j/FunctionToken.java new file mode 100644 index 000000000..6bc620ce3 --- /dev/null +++ b/core/src/de/congrace/exp4j/FunctionToken.java @@ -0,0 +1,161 @@ +/* +Copyright 2011 frank asseg + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Stack; + +/** + * A {@link Token} for functions + * + * @author fas@congrace.de + * + */ +class FunctionToken extends CalculationToken { + /** + * the functionNames that can be used in an expression + * + * @author ruckus + * + */ + enum Function { + ABS, ACOS, ASIN, ATAN, CBRT, CEIL, COS, COSH, EXP, EXPM1, FLOOR, ROUND, RANDOM, LOG, SIN, SINH, SQRT, TAN, TANH, LOG10 + } + + private Function function; + + /** + * construct a new {@link FunctionToken} + * + * @param value + * the name of the function + * @throws UnknownFunctionException + * if an unknown function name is encountered + */ + FunctionToken(String value) throws UnknownFunctionException { + super(value); + try { + function = Function.valueOf(value.toUpperCase()); + } catch (IllegalArgumentException e) { + throw new UnknownFunctionException(value); + } + if (function == null) { + throw new UnknownFunctionException(value); + } + } + + /** + * apply a function to a variable + * + * @param x + * the value the function should be applied to + * @return the result of the function + */ + public Variable applyFunction(Variable var) { + + // The names here are strictly unused, but are useful for debugging + String name = function.name() + " result (#"+var.hashCode()+"), "; + + switch (var.getPrimary()) { + case DOUBLE: + name = "double "+name; + double x = var.getDoubleValue(); + return new Variable(name, applyFunction(x) ); + + case ARRAY: + name = "array "+name; + double[] input = var.getArrayValue(); + double[] result = new double[input.length]; + for (int i = 0; i < input.length; i++){ + result[i] = applyFunction(input[i]); + } + return new Variable(name, result); + + default: + return new Variable("Invalid"); + } + } + + /* + * The actual function application on a double + */ + private double applyFunction(double x){ + switch (function) { + case ABS: + return Math.abs(x); + case ACOS: + return Math.acos(x); + case ASIN: + return Math.asin(x); + case ATAN: + return Math.atan(x); + case CBRT: + return Math.cbrt(x); + case CEIL: + return Math.ceil(x); + case COS: + return Math.cos(x); + case COSH: + return Math.cosh(x); + case EXP: + return Math.exp(x); + case EXPM1: + return Math.expm1(x); + case FLOOR: + return Math.floor(x); + case ROUND: + return Math.round(x); + case RANDOM: + return Math.random()*x; + case LOG: + return Math.log(x); + case LOG10: + return Math.log10(x); + case SIN: + return Math.sin(x); + case SINH: + return Math.sinh(x); + case SQRT: + return Math.sqrt(x); + case TAN: + return Math.tan(x); + case TANH: + return Math.tanh(x); + default: + return Double.NaN; // should not happen ;) + } + } + + /** + * + * get the {@link Function} + * + * @return the correspoding {@link Function} + */ + Function getFunction() { + return function; + } + + @Override + void mutateStackForCalculation(Stack stack, VariableSet variableValues) { + stack.push(this.applyFunction(stack.pop())); + } + + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + operatorStack.push(this); + } +} diff --git a/core/src/de/congrace/exp4j/InfixTranslator.java b/core/src/de/congrace/exp4j/InfixTranslator.java new file mode 100644 index 000000000..9712bce38 --- /dev/null +++ b/core/src/de/congrace/exp4j/InfixTranslator.java @@ -0,0 +1,109 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Set; +import java.util.Stack; + +/** + * Translate a mathematical expression in human readable infix notation to a + * Reverse Polish Notation (postfix) expression for easier parsing. by + * implementing the shunting yard algorithm by dijkstra + * + * @author fas@congrace.de + */ +class InfixTranslator { + + private static String substituteUnaryOperators(String expr) { + final StringBuilder exprBuilder = new StringBuilder(expr.length()); + final char[] data = expr.toCharArray(); + char lastChar = ' '; + for (int i = 0; i < expr.length(); i++) { + if (exprBuilder.length() > 0) { + lastChar = exprBuilder.charAt(exprBuilder.length() - 1); + } + final char c = data[i]; + switch (c) { + case '+': + if (i > 0 && lastChar != '(' && !(OperatorToken.isOperator(lastChar))) { + exprBuilder.append(c); + } + break; + case '-': + if (i > 0 && lastChar != '(' && !(OperatorToken.isOperator(lastChar))) { + exprBuilder.append(c); + } else { + exprBuilder.append('#'); + } + break; + default: + if (!Character.isWhitespace(c)) { + exprBuilder.append(c); + } + } + } + return exprBuilder.toString(); + } + + /** + * Delegation method for simple expression without variables or custom + * functions + * + * @param infixExpression + * the infix expression to be translated + * @return translated RNP postfix expression + * @throws UnparsableExpressionException + * when the expression is invalid + * @throws UnknownFunctionException + * when an unknown function has been used in the input. + */ + static String toPostfixExpression(String infixExpression) throws UnparsableExpressionException, UnknownFunctionException { + return toPostfixExpression(infixExpression, null, null); + } + + /** + * implement the shunting yard algorithm + * + * @param infixExpression + * the human readable expression which should be translated to + * RPN + * @param variableNames + * the variable names used in the expression + * @param customFunctions + * the CustomFunction implementations used + * @return the expression in postfix format + * @throws UnparsableExpressionException + * if the expression could not be translated to RPN + * @throws UnknownFunctionException + * if an unknown function was encountered + */ + static String toPostfixExpression(String infixExpression, String[] variableStrings, Set customFunctions) + throws UnparsableExpressionException, UnknownFunctionException { + infixExpression = substituteUnaryOperators(infixExpression); + final Token[] tokens = new Tokenizer(variableStrings, customFunctions).tokenize(infixExpression); + final StringBuilder output = new StringBuilder(tokens.length); + final Stack operatorStack = new Stack(); + for (final Token token : tokens) { + token.mutateStackForInfixTranslation(operatorStack, output); + } + // all tokens read, put the rest of the operations on the output; + while (operatorStack.size() > 0) { + output.append(operatorStack.pop().getValue()).append(" "); + } + return output.toString().trim(); + } +} diff --git a/core/src/de/congrace/exp4j/InvalidCustomFunctionException.java b/core/src/de/congrace/exp4j/InvalidCustomFunctionException.java new file mode 100644 index 000000000..e3810db06 --- /dev/null +++ b/core/src/de/congrace/exp4j/InvalidCustomFunctionException.java @@ -0,0 +1,9 @@ +package de.congrace.exp4j; + +public class InvalidCustomFunctionException extends Exception{ + private static final long serialVersionUID = 1L; + + public InvalidCustomFunctionException(String message) { + super(message); + } +} diff --git a/core/src/de/congrace/exp4j/NumberToken.java b/core/src/de/congrace/exp4j/NumberToken.java new file mode 100644 index 000000000..b765d4515 --- /dev/null +++ b/core/src/de/congrace/exp4j/NumberToken.java @@ -0,0 +1,66 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Map; +import java.util.Stack; + +/** + * A {@link Token} for Numbers + * + * @author fas@congrace.de + * + */ +class NumberToken extends CalculationToken { + + private final double doubleValue; + + /** + * construct a new {@link NumberToken} + * + * @param value + * the value of the number as a {@link String} + */ + NumberToken(String value) { + super(value); + this.doubleValue = Double.parseDouble(value); + } + + @Override + public boolean equals(Object obj) { + if (obj instanceof NumberToken) { + final NumberToken t = (NumberToken) obj; + return t.getValue().equals(this.getValue()); + } + return false; + } + + @Override + public int hashCode() { + return getValue().hashCode(); + } + + @Override + void mutateStackForCalculation(Stack stack, VariableSet variables) { + stack.push(new Variable("From number "+getValue()+" : "+hashCode(), this.doubleValue)); + } + + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + output.append(this.getValue()).append(' '); + } +} diff --git a/core/src/de/congrace/exp4j/OperatorToken.java b/core/src/de/congrace/exp4j/OperatorToken.java new file mode 100644 index 000000000..765f45083 --- /dev/null +++ b/core/src/de/congrace/exp4j/OperatorToken.java @@ -0,0 +1,243 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Stack; + +/** + * {@link Token} for Operations like +,-,*,/,% and ^ + * + * @author fas@congrace.de + */ +class OperatorToken extends CalculationToken { + + /** + * the valid {@link Operation}s for the {@link OperatorToken} + * + * @author fas@congrace.de + */ + enum Operation { + ADDITION(1, true), SUBTRACTION(1, true), MULTIPLICATION(2, true), DIVISION(2, true), MODULO(2, true), EXPONENTIATION(3, false), UNARY_MINUS(4, false), UNARY_PLUS( + 4, false); + private final int precedence; + private final boolean leftAssociative; + + private Operation(int precedence, boolean leftAssociative) { + this.precedence = precedence; + this.leftAssociative = leftAssociative; + } + } + + /** + * return a corresponding {@link Operation} for a symbol + * + * @param c + * the symbol of the operation + * @return the corresponding {@link Operation} + */ + static Operation getOperation(char c) { + switch (c) { + case '+': + return Operation.ADDITION; + case '-': + return Operation.SUBTRACTION; + case '*': + return Operation.MULTIPLICATION; + case '/': + return Operation.DIVISION; + case '^': + return Operation.EXPONENTIATION; + case '#': + return Operation.UNARY_MINUS; + case '%': + return Operation.MODULO; + default: + return null; + } + } + + static boolean isOperator(char c) { + return getOperation(c) != null; + } + + private final Operation operation; + + /** + * construct a new {@link OperatorToken} + * + * @param value + * the symbol (e.g.: '+') + * @param operation + * the {@link Operation} of this {@link Token} + */ + OperatorToken(String value, Operation operation) { + super(value); + this.operation = operation; + } + + /** + * apply the {@link Operation} + * + * @param values + * the doubles to operate on + * @return the result of the {@link Operation} + * @throws UnparsableExpressionException + */ + public Variable applyOperation(Variable... values) { + + values = expandVariables(values); + + double[] inputs = new double[values.length]; + switch (values[0].getPrimary()){ + + case DOUBLE: + for (int i = 0; i stack, VariableSet variables) { + if (this.getOperandCount() == 2) { + final Variable n2 = stack.pop(); + final Variable n1 = stack.pop(); + stack.push(this.applyOperation(n1, n2)); + } else if (this.getOperandCount() == 1) { + final Variable n1 = stack.pop(); + stack.push(this.applyOperation(n1)); + } + } + + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + Token before; + while (!operatorStack.isEmpty() && (before = operatorStack.peek()) != null && (before instanceof OperatorToken || before instanceof FunctionToken)) { + if (before instanceof FunctionToken) { + operatorStack.pop(); + output.append(before.getValue()).append(" "); + } else { + final OperatorToken stackOperator = (OperatorToken) before; + if (this.isLeftAssociative() && this.getPrecedence() <= stackOperator.getPrecedence()) { + output.append(operatorStack.pop().getValue()).append(" "); + } else if (!this.isLeftAssociative() && this.getPrecedence() < stackOperator.getPrecedence()) { + output.append(operatorStack.pop().getValue()).append(" "); + } else { + break; + } + } + } + operatorStack.push(this); + } +} diff --git a/core/src/de/congrace/exp4j/ParenthesisToken.java b/core/src/de/congrace/exp4j/ParenthesisToken.java new file mode 100644 index 000000000..ad8ab0f6d --- /dev/null +++ b/core/src/de/congrace/exp4j/ParenthesisToken.java @@ -0,0 +1,69 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Stack; + +/** + * Token for parenthesis + * + * @author fas@congrace.de + */ +class ParenthesisToken extends Token { + + ParenthesisToken(String value) { + super(value); + } + + @Override + public boolean equals(Object obj) { + if (obj instanceof ParenthesisToken) { + final ParenthesisToken t = (ParenthesisToken) obj; + return t.getValue().equals(this.getValue()); + } + return false; + } + + @Override + public int hashCode() { + return getValue().hashCode(); + } + + /** + * check the direction of the parenthesis + * + * @return true if it's a left parenthesis (open) false if it is a right + * parenthesis (closed) + */ + boolean isOpen() { + return getValue().equals("(") || getValue().equals("[") || getValue().equals("{"); + } + + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + if (this.isOpen()) { + operatorStack.push(this); + } else { + Token next; + while ((next = operatorStack.peek()) instanceof OperatorToken || next instanceof FunctionToken || next instanceof CustomFunction + || (next instanceof ParenthesisToken && !((ParenthesisToken) next).isOpen())) { + output.append(operatorStack.pop().getValue()).append(" "); + } + operatorStack.pop(); + } + } +} diff --git a/core/src/de/congrace/exp4j/PostfixExpression.java b/core/src/de/congrace/exp4j/PostfixExpression.java new file mode 100644 index 000000000..0bbcc1426 --- /dev/null +++ b/core/src/de/congrace/exp4j/PostfixExpression.java @@ -0,0 +1,116 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Set; +import java.util.Stack; + +/** + * Class for calculating values from a RPN postfix expression.
+ * The default way to create a new instance of {@link PostfixExpression} is by + * using the static factory method fromInfix() + * + * @author fas@congrace.de + */ +public final class PostfixExpression extends AbstractExpression implements Calculable { + + private VariableSet variables = new VariableSet(); + + /** + * Factory method for creating {@link PostfixExpression}s from human + * readable infix expressions + * + * @param expression + * the infix expression to be used + * @return an equivalent {@link PostfixExpression} + * @throws UnparsableExpressionException + * if the expression was invalid + * @throws UnknownFunctionException + * if an unknown function has been used + * @deprecated please use {@link ExpressionBuilder} API + */ + @Deprecated + public static PostfixExpression fromInfix(String expression) throws UnparsableExpressionException, UnknownFunctionException { + return fromInfix(expression, null); + } + + /** + * Factory method for creating {@link PostfixExpression}s from human + * readable infix expressions + * + * @param expression + * the infix expression to be used + * @param customFunctions + * the CustomFunction implementations used + * @return an equivalent {@link PostfixExpression} + * @throws UnparsableExpressionException + * if the expression was invalid + * @throws UnknownFunctionException + * if an unknown function has been used + * @deprecated please use {@link ExpressionBuilder} + */ + @Deprecated + public static PostfixExpression fromInfix(String expression, Set customFunctions) throws UnparsableExpressionException, + UnknownFunctionException { + String[] variableStrings = null; + int posStart, posEnd; + if ((posStart = expression.indexOf('=')) > 0) { + String functionDef = expression.substring(0, posStart); + expression = expression.substring(posStart + 1); + if ((posStart = functionDef.indexOf('(')) > 0 && (posEnd = functionDef.indexOf(')')) > 0) { + variableStrings = functionDef.substring(posStart + 1, posEnd).split(","); + } + } + return new PostfixExpression(InfixTranslator.toPostfixExpression(expression, variableStrings, customFunctions), variableStrings, customFunctions); + } + + /** + * Construct a new simple {@link PostfixExpression} + * + * @param expression + * the postfix expression to be calculated + * @param variableNames + * the variable names in the expression + * @param customFunctions + * the CustomFunction implementations used + * @throws UnparsableExpressionException + * when expression is invalid + * @throws UnknownFunctionException + * when an unknown function has been used + */ + private PostfixExpression(String expression, String[] variableStrings, Set customFunctions) throws UnparsableExpressionException, + UnknownFunctionException { + super(expression, new Tokenizer(variableStrings, customFunctions).tokenize(expression), variableStrings); + } + + /** + * delegate the calculation of a simple expression + */ + public Variable calculate() throws IllegalArgumentException { + + final Stack stack = new Stack(); + for (final Token t : getTokens()) { + ((CalculationToken) t).mutateStackForCalculation(stack, variables); + } + return stack.pop(); + + } + + public void setVariable(Variable value) { + variables.add(value); + } +} diff --git a/core/src/de/congrace/exp4j/Token.java b/core/src/de/congrace/exp4j/Token.java new file mode 100644 index 000000000..2ce4030af --- /dev/null +++ b/core/src/de/congrace/exp4j/Token.java @@ -0,0 +1,50 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Stack; + +/** + * Superclass for tokenized Strings + * + * @author fas@congrace.de + */ +abstract class Token { + private final String value; + + /** + * construct a new {@link Token} + * + * @param value + * the value of the {@link Token} + */ + Token(String value) { + super(); + this.value = value; + } + + /** + * get the value (String representation) of the token + * + * @return the value + */ + String getValue() { + return value; + } + + abstract void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output); +} diff --git a/core/src/de/congrace/exp4j/Tokenizer.java b/core/src/de/congrace/exp4j/Tokenizer.java new file mode 100644 index 000000000..1591995ea --- /dev/null +++ b/core/src/de/congrace/exp4j/Tokenizer.java @@ -0,0 +1,222 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.ArrayList; +import java.util.HashSet; +import java.util.List; +import java.util.Set; + +import de.congrace.exp4j.FunctionToken.Function; + +/** + * Class for tokenizing mathematical expressions by breaking an expression up + * into multiple different {@link Token}s + * + * @author fas@congrace.de + */ +class Tokenizer { + private String[] variableNames; + private final Set functionNames = new HashSet(); + private final Set customFunctions; + + { + functionNames.add("abs"); + functionNames.add("acos"); + functionNames.add("asin"); + functionNames.add("atan"); + functionNames.add("cbrt"); + functionNames.add("ceil"); + functionNames.add("cos"); + functionNames.add("cosh"); + functionNames.add("exp"); + functionNames.add("expm1"); + functionNames.add("floor"); + functionNames.add("log"); + functionNames.add("sin"); + functionNames.add("sinh"); + functionNames.add("sqrt"); + functionNames.add("tan"); + functionNames.add("tanh"); + } + + Tokenizer() { + super(); + customFunctions = null; + } + + /** + * construct a new Tokenizer that recognizes variable names + * + * @param variableNames + * the variable names in the expression + * @throws IllegalArgumentException + * if a variable has the name as a function + * @param customFunctions + * the CustomFunction implementations used if the variableNames + * are not valid + */ + Tokenizer(String[] variableNames, Set customFunctions) throws IllegalArgumentException { + super(); + this.variableNames = variableNames; + + if (variableNames != null) { + for (String varName : variableNames) { + if (functionNames.contains(varName.toLowerCase())) { + throw new IllegalArgumentException("Variable '" + varName + "' can not have the same name as a function"); + } + } + } + this.customFunctions = customFunctions; + } + + private Token getCustomFunctionToken(String name) throws UnknownFunctionException { + for (CustomFunction func : customFunctions) { + if (func.getValue().equals(name)) { + return func; + } + } + throw new UnknownFunctionException(name); + } + + private boolean isCustomFunction(String name) { + if (customFunctions == null) { + return false; + } + for (CustomFunction func : customFunctions) { + if (func.getValue().equals(name)) { + return true; + } + } + return false; + } + + /** + * check if a char is part of a number + * + * @param c + * the char to be checked + * @return true if the char is part of a number + */ + private boolean isDigit(char c) { + return Character.isDigit(c) || c == '.'; + } + + private boolean isFunction(String name) { + for (Function fn : Function.values()) { + if (fn.name().equals(name.toUpperCase())) { + return true; + } + } + return false; + } + + /** + * check if a String is a variable name + * + * @param name + * the variable name which is checked to be valid the char to be + * checked + * @return true if the char is a variable name (e.g. x) + */ + private boolean isVariable(String name) { + //String[] variableNames = variables.getVariableNames(); + + if (variableNames != null) { + for (String var : variableNames) { + if (name.equals(var)) { + return true; + } + } + } + return false; + } + + /** + * tokenize an infix expression by breaking it up into different + * {@link Token} that can represent operations,functions,numbers, + * parenthesis or variables + * + * @param infix + * the infix expression to be tokenized + * @return the {@link Token}s representing the expression + * @throws UnparsableExpressionException + * when the expression is invalid + * @throws UnknownFunctionException + * when an unknown function name has been used. + */ + Token[] tokenize(String infix) throws UnparsableExpressionException, UnknownFunctionException { + final List tokens = new ArrayList(); + final char[] chars = infix.toCharArray(); + // iterate over the chars and fork on different types of input + Token lastToken; + for (int i = 0; i < chars.length; i++) { + char c = chars[i]; + if (c == ' ') + continue; + if (isDigit(c)) { + final StringBuilder valueBuilder = new StringBuilder(1); + // handle the numbers of the expression + valueBuilder.append(c); + int numberLen = 1; + while (chars.length > i + numberLen && isDigit(chars[i + numberLen])) { + valueBuilder.append(chars[i + numberLen]); + numberLen++; + } + i += numberLen - 1; + lastToken = new NumberToken(valueBuilder.toString()); + } else if (Character.isLetter(c) || c == '_' || c == '#') { + // can be a variable or function + final StringBuilder nameBuilder = new StringBuilder(); + nameBuilder.append(c); + int offset = 1; + while (chars.length > i + offset && (Character.isLetter(chars[i + offset]) || Character.isDigit(chars[i + offset]) || chars[i + offset] == '_' || chars[i + offset] == '#')) { + nameBuilder.append(chars[i + offset++]); + } + String name = nameBuilder.toString(); + if (this.isVariable(name)) { + // a variable + i += offset - 1; + lastToken = new VariableToken(name); + } else if (this.isFunction(name)) { + // might be a function + i += offset - 1; + lastToken = new FunctionToken(name); + } else if (this.isCustomFunction(name)) { + // a custom function + i += offset - 1; + lastToken = getCustomFunctionToken(name); + } else { + // an unknown symbol was encountered + throw new UnparsableExpressionException(c, i); + } + }else if (c == ',') { + // a function separator, hopefully + lastToken=new FunctionSeparatorToken(); + } else if (OperatorToken.isOperator(c)) { + lastToken = new OperatorToken(String.valueOf(c), OperatorToken.getOperation(c)); + } else if (c == '(' || c == ')' || c == '[' || c == ']' || c == '{' || c == '}') { + lastToken = new ParenthesisToken(String.valueOf(c)); + } else { + // an unknown symbol was encountered + throw new UnparsableExpressionException(c, i); + } + tokens.add(lastToken); + } + return tokens.toArray(new Token[tokens.size()]); + } +} diff --git a/core/src/de/congrace/exp4j/UnknownFunctionException.java b/core/src/de/congrace/exp4j/UnknownFunctionException.java new file mode 100644 index 000000000..ae350932e --- /dev/null +++ b/core/src/de/congrace/exp4j/UnknownFunctionException.java @@ -0,0 +1,37 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +/** + * Exception for handling unknown Functions. + * + * @see FunctionToken + * @author fas@congrace.de + */ +public class UnknownFunctionException extends Exception { + private static final long serialVersionUID = 1L; + + /** + * construct a new {@link UnknownFunctionException} + * + * @param functionName + * the function name which could not be found + */ + public UnknownFunctionException(String functionName) { + super("Unknown function: " + functionName); + } +} diff --git a/core/src/de/congrace/exp4j/UnparsableExpressionException.java b/core/src/de/congrace/exp4j/UnparsableExpressionException.java new file mode 100644 index 000000000..fcbf7da2d --- /dev/null +++ b/core/src/de/congrace/exp4j/UnparsableExpressionException.java @@ -0,0 +1,47 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +/** + * Exception for invalid expressions + * + * @author fas@congrace.de + */ +public class UnparsableExpressionException extends Exception { + private static final long serialVersionUID = 1L; + + /** + * construct a new {@link UnparsableExpressionException} + * + * @param c + * the character which could not be parsed + * @param pos + * the position of the character in the expression + */ + public UnparsableExpressionException(char c, int pos) { + super("Unable to parse character at position " + pos + ": '" + String.valueOf(c) + "'"); + } + /** + * construct a new {@link UnparsableExpressionException} + * + * @param msg + * the error message + */ + public UnparsableExpressionException(String msg) { + super(msg); + } +} diff --git a/core/src/de/congrace/exp4j/Variable.java b/core/src/de/congrace/exp4j/Variable.java new file mode 100644 index 000000000..0030e70b9 --- /dev/null +++ b/core/src/de/congrace/exp4j/Variable.java @@ -0,0 +1,107 @@ +package de.congrace.exp4j; + +/* + * Represents a generic variable which can have double or array values. + * Optionally the start and step values corresponding to each array index can be specified for array values + * Tries to do something sensible if you try and apply a regular function / operator to an array + * and vice-versa. + */ +public class Variable { + + // The primary or preferred representation + public enum Primary {DOUBLE, ARRAY, PLACEHOLDER}; + private final Primary primary; + + private final String name; + + private final double doubleValue; + private final double[] arrayValue; + + private final double start, step; + + /* + * Initialize a new variable with a name only. This can be used as a place holder + */ + public Variable(String name){ + this.name = name; + this.primary = Primary.PLACEHOLDER; + this.doubleValue = Double.NaN; + this.arrayValue = new double[] {Double.NaN}; + this.start = Double.NaN; + this.step = Double.NaN; + } + + /* + * Initialize a new double variable + */ + public Variable(String name, double d){ + this.doubleValue = d; + this.arrayValue = new double[] {d}; + this.name = name; + this.primary = Primary.DOUBLE; + this.start = Double.NaN; + this.step = Double.NaN; + } + + /* + * Initialize a new array variable + */ + public Variable(String name, double[] d){ + this.arrayValue = d; + this.doubleValue = d[0]; + this.name = name; + this.primary = Primary.ARRAY; + this.start = Double.NaN; + this.step = Double.NaN; + } + + /* + * Initialize a new array variable, specifying the start and step values + */ + public Variable(String name, double[] d, double start, double step){ + this.arrayValue = d; + this.doubleValue = d[0]; + this.name = name; + this.primary = Primary.ARRAY; + this.start = start; + this.step = step; + } + + public String getName(){ + return name; + } + + public Primary getPrimary(){ + return this.primary; + } + + public double getDoubleValue(){ + return doubleValue; + } + + public double[] getArrayValue(){ + return arrayValue; + } + + public double getStep(){ + return step; + } + + public double getStart(){ + return start; + } + + public String toString(){ + if ( arrayValue.length > 1 ){ + String out = name + " is Array (length " + new Integer(arrayValue.length).toString() + ") : {"; + for (double x : arrayValue){ + out = out + x + ","; + } + out = out.substring(0, out.length()-1); + return out + "}"; + } + else{ + return name + " is double : {" + new Double(doubleValue).toString() + "}"; + } + } +} \ No newline at end of file diff --git a/core/src/de/congrace/exp4j/VariableSet.java b/core/src/de/congrace/exp4j/VariableSet.java new file mode 100644 index 000000000..f567006fe --- /dev/null +++ b/core/src/de/congrace/exp4j/VariableSet.java @@ -0,0 +1,42 @@ +package de.congrace.exp4j; + +import java.util.HashSet; + +public class VariableSet extends HashSet { + + /** + * + */ + private static final long serialVersionUID = -4212803364398351279L; + + public boolean add(Variable v){ + Variable previous = getVariableNamed(v.getName()); + if ( previous != null ){ + this.remove( previous ); + } + + return super.add(v); + } + + public Variable getVariableNamed(String name){ + for (Variable var : this){ + if (var.getName().equals(name) ){ + return var; + } + } + return null; + } + + public String[] getVariableNames(){ + if (this.size() == 0){ + return null; + } + String names[] = new String[this.size()]; + int i = 0; + for (Variable var : this){ + names[i] = var.getName(); + i++; + } + return names; + } +} diff --git a/core/src/de/congrace/exp4j/VariableToken.java b/core/src/de/congrace/exp4j/VariableToken.java new file mode 100644 index 000000000..716ef2eed --- /dev/null +++ b/core/src/de/congrace/exp4j/VariableToken.java @@ -0,0 +1,47 @@ +/* + Copyright 2011 frank asseg + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + */ +package de.congrace.exp4j; + +import java.util.Stack; + +/** + * A {@link Token} for representing variables + * + * @author fas + */ +class VariableToken extends CalculationToken { + /** + * construct a new {@link VariableToken} + * + * @param value + * the value of the token + */ + VariableToken(String value) { + super(value); + } + + @Override + void mutateStackForCalculation(Stack stack, VariableSet variableValues) { + Variable value = variableValues.getVariableNamed(this.getValue()); + stack.push(value); + } + + @Override + void mutateStackForInfixTranslation(Stack operatorStack, StringBuilder output) { + output.append(this.getValue()).append(" "); + } +}