/+dub.sdl:

dependency "pegged" version="~>0.4.2"

+/

import pegged.grammar;

import std.stdio;

​

mixin(grammar(`

Arithmetic:

    Term     < Factor (Add / Sub)*

    Add      < "+" Factor

    Sub      < "-" Factor

    Factor   < Primary (Mul / Div)*

    Mul      < "*" Primary

    Div      < "/" Primary

    Primary  < Parens / Neg / Pos / Number / Variable

    Parens   < "(" Term ")"

    Neg      < "-" Primary

    Pos      < "+" Primary

    Number   < ~([0-9]+)

​

    Variable <- identifier

`));

​

void main()

{

    // Parsing at compile-time:

    enum parseTree1 = Arithmetic("1 + 2 - (3*x-5)*6");

​

    pragma(msg, parseTree1.matches);

    assert(parseTree1.matches == ["1", "+", "2", "-", "(", "3", "*", "x", "-", "5", ")", "*", "6"]);

    writeln(parseTree1);

​

    // And at runtime too:

    auto parseTree2 = Arithmetic(" 0 + 123 - 456 ");

    assert(parseTree2.matches == ["0", "+", "123", "-", "456"]);

}