vkvashistha/SimpleExpressionEvaluator

Evaluate boolean expressions with symbol table support

Simple Expression Evaluator

Similar to Javascript eval(), this library evaluate boolean expressions or simple mathematical expressions with variables (or Symbol table) support. Following operators are supported:-
'<', '>', '<=', '>=', '==', '!=', '+', '-', '*', '/', '&&', '||', '!'

Usage

Expression.eval("1+2").asString(); // returns "3.0"
Expression.eval("1+2").asInt(); // returns 3
Expression.eval("2>3").asString(); // returns "false"
Expression.eval("2>3").asBoolean(); // returns false
Expression.eval("(3>2)||((2<4)&&(2>1))").asString(); // returns "true"

With Symbol Table

HashMap<String, Object> st = new HashMap<String, Object>();  
st.put("a",1);  
st.put("b",2);  
st.put("c",3);  
st.put("d",4);  
Expression.eval("a+b", st).asInt();  // or simply asString()
Expression.eval("a>b",st).asBoolean();  // or simply asString()
Expression.eval("(c>b)||((b<d)&&(b>a))",st).asBoolean();  // or simply asString()
Expression.eval("(c>2)||((2<d)&&(b>1))",st).asBoolean();  // or simply asString()

Create Expression using Expression Builder

Expression.expressionBuilder().putSymbol("a",2).putSymbol("b",3).build("(b>a)").evaluate();