rust-expr

Easy DSL.

lib.rs:

Value Expr

DSL

Value:
    i32
    | Unary
    | Binary
    | Assign
    | Paren
    | FuncLike
    | Ident
Unary:
    - Value
    | ! Value
Binary:
    Value + Value
    | Value - Value
    | Value * Value
    | Value / Value
    | Value % Value
    | Value ^ Value
    | Value & Value
    | Value | Value
    | Value << Value
    | Value >> Value
    | Value == Value
    | Value != Value
    | Value > Value
    | Value < Value
    | Value >= Value
    | Value <= Value
    | Value && Value
    | Value || Value
Assign:
    Ident = Value
    | Ident += Value
    | Ident -= Value
    | Ident *= Value
    | Ident /= Value
    | Ident %= Value
    | Ident ^= Value
    | Ident &= Value
    | Ident |= Value
    | Ident <<= Value
    | Ident >>= Value
Paren:
    ( Values )
FuncLike:
    Ident ( Values )
Values:
    <nothing>
    | ValuesNext
ValuesNext:
    Value
    | Value , ValuesNext
Ident:
    <the rust lang ident>

Binary

Here is the precedence of binary operators, going from strong to weak. Operators at the same precedence level are all left-associative.

If you're unsure about operator precedence, use parentheses to explicitly enforce the desired evaluation order.

When mixing numerical and logical operations, any numeric value not 0 is considered true, otherwise false. The logical value true corresponds to 1 numerically, while false corresponds to 0.

Assign

Assign Operators all right-associative.

FuncLike

FuncLike, a function-like object, is similar to a function in that it takes multiple parameters.

The difference is that it allows lazy evaluation, enabling you to freely control the order of evaluation.