// valString returns the string representation for the value v.
// Setting floatFmt forces an integer value to be formatted in
// normalized floating-point format.
// TODO(gri) Move this code into package exact.
func valString(v exact.Value, floatFmt bool) string {
switch v.Kind() {
case exact.Int:
if floatFmt {
return floatString(v)
}
case exact.Float:
return floatString(v)
case exact.Complex:
re := exact.Real(v)
im := exact.Imag(v)
var s string
if exact.Sign(re) != 0 {
s = floatString(re)
if exact.Sign(im) >= 0 {
s += " + "
} else {
s += " - "
im = exact.UnaryOp(token.SUB, im, 0) // negate im
}
}
// im != 0, otherwise v would be exact.Int or exact.Float
return s + floatString(im) + "i"
}
return v.String()
}
func (check *checker) unary(x *operand, op token.Token) {
switch op {
case token.AND:
// spec: "As an exception to the addressability
// requirement x may also be a composite literal."
if _, ok := unparen(x.expr).(*ast.CompositeLit); ok {
x.mode = variable
}
if x.mode != variable {
check.invalidOp(x.pos(), "cannot take address of %s", x)
x.mode = invalid
return
}
x.typ = &Pointer{base: x.typ}
return
case token.ARROW:
typ, ok := x.typ.Underlying().(*Chan)
if !ok {
check.invalidOp(x.pos(), "cannot receive from non-channel %s", x)
x.mode = invalid
return
}
if typ.dir&ast.RECV == 0 {
check.invalidOp(x.pos(), "cannot receive from send-only channel %s", x)
x.mode = invalid
return
}
x.mode = commaok
x.typ = typ.elem
return
}
if !check.op(unaryOpPredicates, x, op) {
x.mode = invalid
return
}
if x.mode == constant {
typ := x.typ.Underlying().(*Basic)
size := -1
if isUnsigned(typ) {
size = int(check.conf.sizeof(typ))
}
x.val = exact.UnaryOp(op, x.val, size)
// Typed constants must be representable in
// their type after each constant operation.
if isTyped(typ) {
check.isRepresentableAs(x, typ)
}
return
}
x.mode = value
// x.typ remains unchanged
}
func (p *importer) fraction() exact.Value {
sign := p.int()
if sign == 0 {
return exact.MakeInt64(0)
}
x := exact.BinaryOp(p.ufloat(), token.QUO, p.ufloat())
if sign < 0 {
x = exact.UnaryOp(token.SUB, x, 0)
}
return x
}
func doOp(x exact.Value, op token.Token, y exact.Value) (z exact.Value) {
defer panicHandler(&z)
if x == nil {
return exact.UnaryOp(op, y, -1)
}
switch op {
case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
return exact.MakeBool(exact.Compare(x, op, y))
case token.SHL, token.SHR:
s, _ := exact.Int64Val(y)
return exact.Shift(x, op, uint(s))
default:
return exact.BinaryOp(x, op, y)
}
}
func evalAction(n ast.Node) exact.Value {
switch e := n.(type) {
case *ast.BasicLit:
return val(e.Value)
case *ast.BinaryExpr:
x := evalAction(e.X)
if x == nil {
return nil
}
y := evalAction(e.Y)
if y == nil {
return nil
}
switch e.Op {
case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
return exact.MakeBool(exact.Compare(x, e.Op, y))
case token.SHL, token.SHR:
s, _ := exact.Int64Val(y)
return exact.Shift(x, e.Op, uint(s))
default:
return exact.BinaryOp(x, e.Op, y)
}
case *ast.UnaryExpr:
return exact.UnaryOp(e.Op, evalAction(e.X), -1)
case *ast.CallExpr:
fmt.Printf("Can't handle call (%s) yet at pos %d\n", e.Fun, e.Pos())
return nil
case *ast.Ident:
fmt.Printf("Can't handle Ident %s here at pos %d\n", e.Name, e.Pos())
return nil
case *ast.ParenExpr:
return evalAction(e.X)
default:
fmt.Println("Can't handle")
fmt.Printf("n: %s, e: %s\n", n, e)
return nil
}
}