Golang exact.Float64Val函数代码示例

func roundFloat64(x exact.Value) exact.Value {
	f, _ := exact.Float64Val(x)
	if !math.IsInf(f, 0) {
		return exact.MakeFloat64(f)
	}
	return nil
}

// constValString emulates Go 1.6's go/constant.ExactString well enough
// to make the tests pass.  This is just a stopgap until we throw away
// all the *14.go files.
func constValString(v exact.Value) string {
	if v.Kind() == exact.Float {
		f, _ := exact.Float64Val(v)
		return fmt.Sprintf("%g", f)
	}
	return v.String()
}

// FloatVal is a utility function returns a string constant value from an exact.Value.
func (comp *Compilation) FloatVal(eVal exact.Value, bits int, posStr string) string {
	fVal, isExact := exact.Float64Val(eVal)
	if !isExact {
		comp.LogWarning(posStr, "inexact", fmt.Errorf("constant value %g cannot be accurately represented in float64", fVal))
	}
	ret := strconv.FormatFloat(fVal, byte('g'), -1, bits)
	if fVal < 0.0 {
		return fmt.Sprintf("(%s)", ret)
	}
	return ret
}

// Uint64 returns the numeric value of this constant truncated to fit
// an unsigned 64-bit integer.
//
func (c *Const) Uint64() uint64 {
	switch x := c.Value; x.Kind() {
	case exact.Int:
		if u, ok := exact.Uint64Val(x); ok {
			return u
		}
		return 0
	case exact.Float:
		f, _ := exact.Float64Val(x)
		return uint64(f)
	}
	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
}

func (c *funcContext) translateExpr(expr ast.Expr) *expression {
	exprType := c.p.TypeOf(expr)
	if value := c.p.Types[expr].Value; value != nil {
		basic := exprType.Underlying().(*types.Basic)
		switch {
		case isBoolean(basic):
			return c.formatExpr("%s", strconv.FormatBool(exact.BoolVal(value)))
		case isInteger(basic):
			if is64Bit(basic) {
				if basic.Kind() == types.Int64 {
					d, ok := exact.Int64Val(value)
					if !ok {
						panic("could not get exact uint")
					}
					return c.formatExpr("new %s(%s, %s)", c.typeName(exprType), strconv.FormatInt(d>>32, 10), strconv.FormatUint(uint64(d)&(1<<32-1), 10))
				}
				d, ok := exact.Uint64Val(value)
				if !ok {
					panic("could not get exact uint")
				}
				return c.formatExpr("new %s(%s, %s)", c.typeName(exprType), strconv.FormatUint(d>>32, 10), strconv.FormatUint(d&(1<<32-1), 10))
			}
			d, ok := exact.Int64Val(value)
			if !ok {
				panic("could not get exact int")
			}
			return c.formatExpr("%s", strconv.FormatInt(d, 10))
		case isFloat(basic):
			f, _ := exact.Float64Val(value)
			return c.formatExpr("%s", strconv.FormatFloat(f, 'g', -1, 64))
		case isComplex(basic):
			r, _ := exact.Float64Val(exact.Real(value))
			i, _ := exact.Float64Val(exact.Imag(value))
			if basic.Kind() == types.UntypedComplex {
				exprType = types.Typ[types.Complex128]
			}
			return c.formatExpr("new %s(%s, %s)", c.typeName(exprType), strconv.FormatFloat(r, 'g', -1, 64), strconv.FormatFloat(i, 'g', -1, 64))
		case isString(basic):
			return c.formatExpr("%s", encodeString(exact.StringVal(value)))
		default:
			panic("Unhandled constant type: " + basic.String())
		}
	}

	var obj types.Object
	switch e := expr.(type) {
	case *ast.SelectorExpr:
		obj = c.p.Uses[e.Sel]
	case *ast.Ident:
		obj = c.p.Defs[e]
		if obj == nil {
			obj = c.p.Uses[e]
		}
	}

	if obj != nil && typesutil.IsJsPackage(obj.Pkg()) {
		switch obj.Name() {
		case "Global":
			return c.formatExpr("$global")
		case "Module":
			return c.formatExpr("$module")
		case "Undefined":
			return c.formatExpr("undefined")
		}
	}

	switch e := expr.(type) {
	case *ast.CompositeLit:
		if ptrType, isPointer := exprType.(*types.Pointer); isPointer {
			exprType = ptrType.Elem()
		}

		collectIndexedElements := func(elementType types.Type) []string {
			var elements []string
			i := 0
			zero := c.translateExpr(c.zeroValue(elementType)).String()
			for _, element := range e.Elts {
				if kve, isKve := element.(*ast.KeyValueExpr); isKve {
					key, ok := exact.Int64Val(c.p.Types[kve.Key].Value)
					if !ok {
						panic("could not get exact int")
					}
					i = int(key)
					element = kve.Value
				}
				for len(elements) <= i {
					elements = append(elements, zero)
				}
				elements[i] = c.translateImplicitConversionWithCloning(element, elementType).String()
				i++
			}
			return elements
		}

		switch t := exprType.Underlying().(type) {
		case *types.Array:
			elements := collectIndexedElements(t.Elem())
			if len(elements) == 0 {
				return c.formatExpr("%s.zero()", c.typeName(t))
			}
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		if val := c.p.Types[e.(ast.Expr)].Value; val != nil {
			continue
		}
		if !hasAssignments {
			hasAssignments = true
			out.WriteByte('(')
			parens = false
		}
		v := c.newVariable("x")
		out.WriteString(v + " = " + c.translateExpr(e.(ast.Expr)).String() + ", ")
		vars[i] = v
	}

	processFormat(func(b, k uint8, n int) {
		writeExpr := func(suffix string) {
			if vars[n] != "" {
				out.WriteString(vars[n] + suffix)
				return
			}
			out.WriteString(c.translateExpr(a[n].(ast.Expr)).StringWithParens() + suffix)
		}
		switch k {
		case 0:
			out.WriteByte(b)
		case 's':
			if e, ok := a[n].(*expression); ok {
				out.WriteString(e.StringWithParens())
				return
			}
			out.WriteString(a[n].(string))
		case 'd':
			out.WriteString(strconv.Itoa(a[n].(int)))
		case 't':
			out.WriteString(a[n].(token.Token).String())
		case 'e':
			e := a[n].(ast.Expr)
			if val := c.p.Types[e].Value; val != nil {
				out.WriteString(c.translateExpr(e).String())
				return
			}
			writeExpr("")
		case 'f':
			e := a[n].(ast.Expr)
			if val := c.p.Types[e].Value; val != nil {
				d, _ := exact.Int64Val(val)
				out.WriteString(strconv.FormatInt(d, 10))
				return
			}
			if is64Bit(c.p.TypeOf(e).Underlying().(*types.Basic)) {
				out.WriteString("$flatten64(")
				writeExpr("")
				out.WriteString(")")
				return
			}
			writeExpr("")
		case 'h':
			e := a[n].(ast.Expr)
			if val := c.p.Types[e].Value; val != nil {
				d, _ := exact.Uint64Val(val)
				if c.p.TypeOf(e).Underlying().(*types.Basic).Kind() == types.Int64 {
					out.WriteString(strconv.FormatInt(int64(d)>>32, 10))
					return
				}
				out.WriteString(strconv.FormatUint(d>>32, 10))
				return
			}
			writeExpr(".$high")
		case 'l':
			if val := c.p.Types[a[n].(ast.Expr)].Value; val != nil {
				d, _ := exact.Uint64Val(val)
				out.WriteString(strconv.FormatUint(d&(1<<32-1), 10))
				return
			}
			writeExpr(".$low")
		case 'r':
			if val := c.p.Types[a[n].(ast.Expr)].Value; val != nil {
				r, _ := exact.Float64Val(exact.Real(val))
				out.WriteString(strconv.FormatFloat(r, 'g', -1, 64))
				return
			}
			writeExpr(".$real")
		case 'i':
			if val := c.p.Types[a[n].(ast.Expr)].Value; val != nil {
				i, _ := exact.Float64Val(exact.Imag(val))
				out.WriteString(strconv.FormatFloat(i, 'g', -1, 64))
				return
			}
			writeExpr(".$imag")
		case '%':
			out.WriteRune('%')
		default:
			panic(fmt.Sprintf("formatExpr: %%%c%d", k, n))
		}
	})

	if hasAssignments {
		out.WriteByte(')')
	}
	return &expression{str: out.String(), parens: parens}
}

func fitsFloat64(x exact.Value) bool {
	f, _ := exact.Float64Val(x)
	return !math.IsInf(f, 0)
}

// Complex128 returns the complex value of this constant truncated to
// fit a complex128.
//
func (c *Const) Complex128() complex128 {
	re, _ := exact.Float64Val(exact.Real(c.Value))
	im, _ := exact.Float64Val(exact.Imag(c.Value))
	return complex(re, im)
}

// Float64 returns the numeric value of this constant truncated to fit
// a float64.
//
func (c *Const) Float64() float64 {
	f, _ := exact.Float64Val(c.Value)
	return f
}

// newValueFromConst converts a constant value to an LLVM value.
func (fr *frame) newValueFromConst(v exact.Value, typ types.Type) *govalue {
	switch {
	case v == nil:
		llvmtyp := fr.types.ToLLVM(typ)
		return newValue(llvm.ConstNull(llvmtyp), typ)

	case isString(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.String]
		}
		llvmtyp := fr.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(fr.module.Module, init.Type(), "")
			ptr.SetInitializer(init)
			ptr.SetLinkage(llvm.InternalLinkage)
			ptr = llvm.ConstBitCast(ptr, i8ptr)
		} else {
			ptr = llvm.ConstNull(i8ptr)
		}
		len_ := llvm.ConstInt(fr.types.inttype, uint64(strlen), false)
		llvmvalue := llvm.Undef(llvmtyp)
		llvmvalue = llvm.ConstInsertValue(llvmvalue, ptr, []uint32{0})
		llvmvalue = llvm.ConstInsertValue(llvmvalue, len_, []uint32{1})
		return newValue(llvmvalue, typ)

	case isInteger(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Int]
		}
		llvmtyp := fr.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 newValue(llvmvalue, typ)

	case isBoolean(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Bool]
		}
		return newValue(boolLLVMValue(exact.BoolVal(v)), typ)

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

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

	case isComplex(typ):
		if isUntyped(typ) {
			typ = types.Typ[types.Complex128]
		}
		llvmtyp := fr.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 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 := fr.newValueFromConst(v, types.Typ[types.String])
			return fr.convert(strval, typ)
		}
	}

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