module Compiler
open Syntax

type PrimValue =
    | BoolVal of bool
    | IntVal of int

type BinaryOps =
    | ADD
    | MIN
    | MUL
    | DIV

let pushNum i =
    match i with
    | IntVal x -> "ldc.i4.s " + string x
    | _        -> failwith "Syntax error"

let pushOperation op =
    match op with
    | ADD -> "add"
    | MIN -> "sub"
    | MUL -> "mul"
    | DIV -> "div"


let rec eval expr lst =
    match expr with
    | ConstInt i                  -> (pushNum (IntVal i)) :: lst
    | PrimOp ("+", lOper, rOper)  -> evalNumericExpr ADD lOper rOper lst
    | PrimOp ("-", lOper, rOper)  -> evalNumericExpr MIN lOper rOper lst
    | PrimOp ("*", lOper, rOper)  -> evalNumericExpr MUL lOper rOper lst
    | PrimOp ("/", lOper, rOper)  -> evalNumericExpr DIV lOper rOper lst
    | _                 -> failwith "Syntax error"

and evalNumericExpr op lOper rOper lst =
    let left = eval lOper lst
    let right = eval rOper lst
    let operation = pushOperation op
    lst @ left @ right @ [operation]

let compile expr =
    eval expr []