Golang exact.Value类代码示例

// 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 (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))
	}
}

func writeInt(w *bytes.Buffer, ev exact.Value, k types.BasicKind) {
	if k == types.Uintptr {
		u, _ := exact.Uint64Val(ev)
		w.WriteString("0x")
		w.WriteString(strconv.FormatUint(u, 16))
		return
	}

	w.WriteString(ev.String())
	switch k {
	case types.Int32:
		w.WriteByte('L')

	case types.Uint32:
		w.WriteString("UL")

	case types.Int64:
		w.WriteString("LL")

	case types.Uint64:
		w.WriteString("ULL")
	}
}

func (cdd *CDD) Value(w *bytes.Buffer, ev exact.Value, t types.Type) {
	k := t.Underlying().(*types.Basic).Kind()

	// TODO: use t instead ev.Kind() in following switch
	switch ev.Kind() {
	case exact.Int:
		writeInt(w, ev, k)

	case exact.Float:
		writeFloat(w, ev, k)

	case exact.Complex:
		switch k {
		case types.Complex64:
			k = types.Float32
		case types.Complex128:
			k = types.Float64
		default:
			k = types.UntypedFloat
		}
		writeFloat(w, exact.Real(ev), k)
		im := exact.Imag(ev)
		if exact.Sign(im) != -1 {
			w.WriteByte('+')
		}
		writeFloat(w, im, k)
		w.WriteByte('i')

	case exact.String:
		w.WriteString("EGSTR(")
		w.WriteString(ev.String())
		w.WriteByte(')')

	default:
		w.WriteString(ev.String())
	}
}

// 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 {
//.........这里部分代码省略.........

func (c *compiler) NewConstValue(v exact.Value, typ types.Type) *LLVMValue {
	switch {
	case v.Kind() == exact.Unknown:
		// TODO nil literals should be represented more appropriately once the exact-package supports it.
		llvmtyp := c.types.ToLLVM(typ)
		return c.NewValue(llvm.ConstNull(llvmtyp), typ)

	case isString(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.String]
		}
		llvmtyp := c.types.ToLLVM(typ)
		strval := exact.StringVal(v)
		strlen := len(strval)
		i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
		var ptr llvm.Value
		if strlen > 0 {
			init := llvm.ConstString(strval, false)
			ptr = llvm.AddGlobal(c.module.Module, init.Type(), "")
			ptr.SetInitializer(init)
			ptr = llvm.ConstBitCast(ptr, i8ptr)
		} else {
			ptr = llvm.ConstNull(i8ptr)
		}
		len_ := llvm.ConstInt(c.types.inttype, uint64(strlen), false)
		llvmvalue := llvm.Undef(llvmtyp)
		llvmvalue = llvm.ConstInsertValue(llvmvalue, ptr, []uint32{0})
		llvmvalue = llvm.ConstInsertValue(llvmvalue, len_, []uint32{1})
		return c.NewValue(llvmvalue, typ)

	case isInteger(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Int]
		}
		llvmtyp := c.types.ToLLVM(typ)
		var llvmvalue llvm.Value
		if isUnsigned(typ) {
			v, _ := exact.Uint64Val(v)
			llvmvalue = llvm.ConstInt(llvmtyp, v, false)
		} else {
			v, _ := exact.Int64Val(v)
			llvmvalue = llvm.ConstInt(llvmtyp, uint64(v), true)
		}
		return c.NewValue(llvmvalue, typ)

	case isBoolean(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Bool]
		}
		var llvmvalue llvm.Value
		if exact.BoolVal(v) {
			llvmvalue = llvm.ConstAllOnes(llvm.Int1Type())
		} else {
			llvmvalue = llvm.ConstNull(llvm.Int1Type())
		}
		return c.NewValue(llvmvalue, typ)

	case isFloat(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Float64]
		}
		llvmtyp := c.types.ToLLVM(typ)
		floatval, _ := exact.Float64Val(v)
		llvmvalue := llvm.ConstFloat(llvmtyp, floatval)
		return c.NewValue(llvmvalue, typ)

	case typ == types.Typ[types.UnsafePointer]:
		llvmtyp := c.types.ToLLVM(typ)
		v, _ := exact.Uint64Val(v)
		llvmvalue := llvm.ConstInt(llvmtyp, v, false)
		return c.NewValue(llvmvalue, typ)

	case isComplex(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Complex128]
		}
		llvmtyp := c.types.ToLLVM(typ)
		floattyp := llvmtyp.StructElementTypes()[0]
		llvmvalue := llvm.ConstNull(llvmtyp)
		realv := exact.Real(v)
		imagv := exact.Imag(v)
		realfloatval, _ := exact.Float64Val(realv)
		imagfloatval, _ := exact.Float64Val(imagv)
		llvmre := llvm.ConstFloat(floattyp, realfloatval)
		llvmim := llvm.ConstFloat(floattyp, imagfloatval)
		llvmvalue = llvm.ConstInsertValue(llvmvalue, llvmre, []uint32{0})
		llvmvalue = llvm.ConstInsertValue(llvmvalue, llvmim, []uint32{1})
		return c.NewValue(llvmvalue, typ)
	}

	// Special case for string -> [](byte|rune)
	if u, ok := typ.Underlying().(*types.Slice); ok && isInteger(u.Elem()) {
		if v.Kind() == exact.String {
			strval := c.NewConstValue(v, types.Typ[types.String])
			return strval.Convert(typ).(*LLVMValue)
		}
	}

	panic(fmt.Sprintf("unhandled: t=%s(%T), v=%v(%T)", c.types.TypeString(typ), typ, v, v))
}