Add unary '-' operator

elys.nim

@@ -11,10 +11,7 @@ var x = 10
 var y = 20
 print(x + y, 2 + 2 * 2 / 10 * .1)
 
-x += 2
-x += 2
-x += 2
-x *= 2
+x *= -2
 print x
 
 print 7 / 3

modules/ast.nim

@@ -112,6 +112,9 @@ proc floatAst*(val: float): FloatAST = FloatAST(val: val, kind: akFloat)
 proc stringAst*(val: string): StringAST = StringAST(val: val, kind: akString)
 proc boolAst*(val: bool): BoolAST = BoolAST(val: val, kind: akBool)
 
+proc unaryOpAst*(expr: ASTRoot, op: string): UnaryOpAST =
+  UnaryOpAST(expr: expr, op: op)
+
 proc varAst*(val: string): VarAST = VarAST(name: val, kind: akVar)
 
 proc binOpAst*(l, r: ASTRoot, op: string): BinOpAST = BinOpAST(l: l, r: r, op: op, kind: akBinOp)
@@ -233,6 +236,16 @@ method eval*(self: VarAST, env: Environment): ASTRoot =
     raise newException(RuntimeError, "Variable " & self.name & " was not assigned before")
   env.vars[self.name].val
 
+method eval*(self: UnaryOpAST, env: Environment): ASTRoot =
+  let val = self.expr.eval(env)
+  if val.kind == akInt:
+    val.IntAST.val = -val.IntAST.val
+    return val
+  elif val.kind == akFloat:
+    val.FloatAST.val = -val.FloatAST.val
+    return val
+  raise newException(RuntimeError, "Can not to apply unary operator '" & self.op & "' to " & $self.expr)
+
 method eval*(self: StmtList, env: Environment): ASTRoot =
   var environment = newEnv(env)
   for s in self.statements:

modules/parser.nim

@@ -49,7 +49,8 @@ let
     @["+", "-", "%"]
   ]
   relationalOperators = @["==", "!=", ">=", "<=", "<", ">"]
-  unaryOperators = @["--", "++", "-"]
+  incDecOperators = @["--", "++"]
+  unaryOperators = @["-"]
   assignOperators = @["//=", "+=", "-=", "*=", "/=", "="]
   bExprPrecedenceLevels = @[
       @["and", "&&"],
@@ -65,6 +66,9 @@ proc processVar(res: Result): Option[Result] = astRes(varAst(res.val.get))
 proc processGroup(res: Result): Option[Result] = res.valx.valy.some
 
 
+proc unaryOperatorStmt(): Combinator
+
+
 proc aExprValue(): Combinator =
   (
     (intNumber ^ processIntNumber) |
@@ -86,7 +90,8 @@ proc aExprGroup(): Combinator =
 proc aExprTerm(): Combinator =
   (
     aExprValue() |
-    aExprGroup()
+    aExprGroup() |
+    unaryOperatorStmt()
   )
 
 proc processBinOp(res: Result): Option[Result] =
@@ -166,6 +171,14 @@ proc processEof(res: Result): Option[Result] =
   astRes(eofStmt())
 
 
+proc processUnaryOperatorStmt(res: Result): Option[Result] =
+  echo res
+  astRes(unaryOpAst(res.valy.ast, res.valx.val.get))
+proc unaryOperatorStmt(): Combinator =
+  # x = -x
+  (anyOpInList(unaryOperators) + lazy(aExpr)) ^ processUnaryOperatorStmt
+
+
 proc stmt(): Combinator =
   (
     printStmt() |