Пример #1
0
func (p *exporter) value(x exact.Value) {
	if trace {
		p.tracef("value { ")
		defer p.tracef("} ")
	}

	switch kind := x.Kind(); kind {
	case exact.Bool:
		tag := falseTag
		if exact.BoolVal(x) {
			tag = trueTag
		}
		p.int(tag)
	case exact.Int:
		if i, ok := exact.Int64Val(x); ok {
			p.int(int64Tag)
			p.int64(i)
			return
		}
		p.int(floatTag)
		p.float(x)
	case exact.Float:
		p.int(fractionTag)
		p.fraction(x)
	case exact.Complex:
		p.int(complexTag)
		p.fraction(exact.Real(x))
		p.fraction(exact.Imag(x))
	case exact.String:
		p.int(stringTag)
		p.string(exact.StringVal(x))
	default:
		panic(fmt.Sprintf("unexpected value kind %d", kind))
	}
}
Пример #2
0
// representableConst reports whether x can be represented as
// value of the given basic type kind and for the configuration
// provided (only needed for int/uint sizes).
//
// If rounded != nil, *rounded is set to the rounded value of x for
// representable floating-point values; it is left alone otherwise.
// It is ok to provide the addressof the first argument for rounded.
func representableConst(x exact.Value, conf *Config, as BasicKind, rounded *exact.Value) bool {
	switch x.Kind() {
	case exact.Unknown:
		return true

	case exact.Bool:
		return as == Bool || as == UntypedBool

	case exact.Int:
		if x, ok := exact.Int64Val(x); ok {
			switch as {
			case Int:
				var s = uint(conf.sizeof(Typ[as])) * 8
				return int64(-1)<<(s-1) <= x && x <= int64(1)<<(s-1)-1
			case Int8:
				const s = 8
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int16:
				const s = 16
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int32:
				const s = 32
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int64:
				return true
			case Uint, Uintptr:
				if s := uint(conf.sizeof(Typ[as])) * 8; s < 64 {
					return 0 <= x && x <= int64(1)<<s-1
				}
				return 0 <= x
			case Uint8:
				const s = 8
				return 0 <= x && x <= 1<<s-1
			case Uint16:
				const s = 16
				return 0 <= x && x <= 1<<s-1
			case Uint32:
				const s = 32
				return 0 <= x && x <= 1<<s-1
			case Uint64:
				return 0 <= x
			case Float32, Float64, Complex64, Complex128,
				UntypedInt, UntypedFloat, UntypedComplex:
				return true
			}
		}

		n := exact.BitLen(x)
		switch as {
		case Uint, Uintptr:
			var s = uint(conf.sizeof(Typ[as])) * 8
			return exact.Sign(x) >= 0 && n <= int(s)
		case Uint64:
			return exact.Sign(x) >= 0 && n <= 64
		case Float32, Complex64:
			if rounded == nil {
				return fitsFloat32(x)
			}
			r := roundFloat32(x)
			if r != nil {
				*rounded = r
				return true
			}
		case Float64, Complex128:
			if rounded == nil {
				return fitsFloat64(x)
			}
			r := roundFloat64(x)
			if r != nil {
				*rounded = r
				return true
			}
		case UntypedInt, UntypedFloat, UntypedComplex:
			return true
		}

	case exact.Float:
		switch as {
		case Float32, Complex64:
			if rounded == nil {
				return fitsFloat32(x)
			}
			r := roundFloat32(x)
			if r != nil {
				*rounded = r
				return true
			}
		case Float64, Complex128:
			if rounded == nil {
				return fitsFloat64(x)
			}
			r := roundFloat64(x)
			if r != nil {
				*rounded = r
				return true
			}
		case UntypedFloat, UntypedComplex:
			return true
		}

	case exact.Complex:
		switch as {
		case Complex64:
			if rounded == nil {
				return fitsFloat32(exact.Real(x)) && fitsFloat32(exact.Imag(x))
			}
			re := roundFloat32(exact.Real(x))
			im := roundFloat32(exact.Imag(x))
			if re != nil && im != nil {
				*rounded = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))
				return true
			}
		case Complex128:
			if rounded == nil {
				return fitsFloat64(exact.Real(x)) && fitsFloat64(exact.Imag(x))
			}
			re := roundFloat64(exact.Real(x))
			im := roundFloat64(exact.Imag(x))
			if re != nil && im != nil {
				*rounded = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))
				return true
			}
		case UntypedComplex:
			return true
		}

	case exact.String:
		return as == String || as == UntypedString

	default:
		unreachable()
	}

	return false
}