eval_ex

eval_ex

A Dart port of https://github.com/uklimaschewski/EvalEx.
EvalEx supports mathematical and boolean expression evaluation, using arbitrary precision. EvalEx supports functions, variables, and operators and additionally makes it very easy to add your own custom functions or operators.

EvalEx uses decimal to support arbitrary precision arithmetic.
View package on pub.dev.

Basic example

void main() {
  Expression exp = Expression("2 ^ 4 + 8");
  print(exp.eval().toString()); // 24

  // With a variable
  exp = Expression("a ^ b + c");
  // Variables may contain alphanumeric characters, and "_". This can be changed
  // by using setVariableCharacters(..) and setFirstVariableCharacters(..) (what chars variable are allowed to start with).
  exp.setStringVariable("a", "2");
  exp.setStringVariable("b", "4");
  exp.setStringVariable("c", "8");
  print(exp.eval().toString()); // 24
  
  // With a function
  exp = Expression("MAX(-7,8)");
  print(exp.eval().toString()); // 8

  // Boolean logic
  exp = Expression("1>0 && 5 == 5");
  print(exp.eval().toString()); // 1
  
  exp = Expression("1>0 && 5 == 4");
  print(exp.eval().toString()); // 0
}
 

Built-in functions and operators

Adding custom functions, operators, and variables

Custom functions, operators, and variables can be defined by adding them in built_ins.dart

Differences from https://github.com/uklimaschewski/EvalEx.

• Hyperbolic functions aren't supported
• The SQRT function is currently limited to 64-bit precision
• Built in operators/functions/variables are instead defined in built_ins.dart