Expr is a simple, lightweight and performant programming toolkit for evaluating basic mathematical expression and boolean expression. The resulting value is one of these following primitive types: string, boolean, numerical (complex, float, integer).

Supported Numerical Notations

- Binary (base-2)       : 0b1011
- Octal (base-8)        : 0o13 or 013
- Decimal (base-10)     : 11
- Hexadecimal (base-16) : 0xB
- Scientific            : 11e0

Expression Examples

"1 + 1"             -> 2
"1.0 / 2"           -> 0.5
"2 < 2 + 2"         -> true
"true && !false"    -> true
"4 << 10"           -> 4096
"0b0100 << 0b1010"  -> 4096 (0b1000000000000)
"0x4 << 0xA"        -> 4096 (0x1000)
"0o4 << 0o12"       -> 4096 (0o10000)
"0b1000 | 0b1001"   -> 9 (0b1001)
"(2+1i) + (2+2i)"   -> (4+3i)
"0x4 << 0xA > 1024" -> true

Usage

Bind

For binding variables into expr string, see Bind

Explain (Experimental)

For explaining step-by-step operations, see Explain

Any

• Any parses the given expr string into any type it returns as a result. e.g:
  • "1 < 2" -> true
  • "true || false" -> true
  • "2 + 2" -> 4
  • "4 << 10" -> 4906
  • "2.2 + 2" -> 4.2
  • "(2+1i) + (2+2i)" -> (4+3i)
  • ""abc" == "abc"" -> true
  • ""abc"" -> "abc"
• Supported operators:
  • Comparison: [==, !=, <, <=, >, >=]
  • Logical: [&&, ||, !]
  • Arithmetic: [+, -, *, /, %] (% operator does not work for complex number)
  • Bitwise: [&, |, ^, &^, <<, >>] (only work for integer values)

    str := "(2+1i) + (2+2i)"
    v, err := expr.Any(str)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%v", v) // (4+3i)

Boolean

• Bool parses the given expr string into boolean as a result. e.g:
  • "1 < 2" -> true
  • "1 > 2" -> false
  • "true || false" -> true
  • "true && !false" -> true
• Arithmetic operation are supported. e.g:
  • "1 + 2 > 1" -> true
  • "(1 * 10) > -2" -> true
• Supported operators:
  • Comparison: [==, !=, <, <=, >, >=]
  • Logical: [&&, ||, !]
  • Arithmetic: [+, -, *, /, %] (% operator does not work for complex number)
  • Bitwise: [&, |, ^, &^, <<, >>] (only work for integer values)

    str := "((1 < 2 && 3 > 4) || 1 == 1) && 4 < 5"
    v, err := expr.Bool(str)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%t", v) // true

Complex128

• Complex128 parses the given expr string into complex128 as a result. e.g:
  • "(2+1i) + (2+2i)" -> (4+3i)
  • "(2.2+1i) + 2" -> (4.2+1i)
  • "2 + 2" -> (4+0i)
• Supported operators:
  • Arithmetic: [+, -, *, /]

    str := "(2+1i) + (2+2i)"
    v, err := expr.Complex128(str)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%f", v) // (4+3i)

Float64

• Float64 parses the given expr string into float64 as a result. e.g:
  • "2 + 2" -> 4
  • "2.2 + 2" -> 4.2
  • "10 * -5 + (-5.5)" -> -55.5
  • "10.0 % 2.6" -> 2.2
• Supported operators:
  • Arithmetic: [+, -, *, /, %]

    str := "((2 * 2) * (8 + 2) * 2) + 2.56789"
    v, err := expr.Float64(str)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%f", v) // 82.56789

Int64

• Int64 parses the given expr string into int64 as a result. e.g:
  • "2 + 2" -> 4
  • "2.2 + 2" -> 4
  • "10 + ((-5 * -10) / -10) - 2" -> 3
• Supported operators:
  • Arithmetic: [+, -, *, /, %]
  • Bitwise: [&, |, ^, &^, <<, >>]

    str := "((2 * 2) * (8 + 2) * 2) + 2.56789"
    v, err := expr.Int64(str)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%d", v) // 82

Int64Strict

• Int64Strict is shorthand for Int64(str) but when x / y and y == 0, it will return ErrIntegerDividedByZero

    str := "12 + 24 - 10/0"
    v, err := expr.Int64Strict(str)
    if err != nil {
        // err == ErrIntegerDividedByZero
    }
    fmt.Printf("%d", v) // 0

Int

• Int is shorthand for Int64(str) with its result will be converted into int.

    str := "1 + 10"
    v, err := expr.Int(str)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%d", v) // 11

License

Expr is released under Apache Licence 2.0