Golang exact.MakeImag函數代碼示例

func (p *importer) value() exact.Value {
	switch kind := exact.Kind(p.int()); kind {
	case falseTag:
		return exact.MakeBool(false)
	case trueTag:
		return exact.MakeBool(true)
	case int64Tag:
		return exact.MakeInt64(p.int64())
	case floatTag:
		return p.float()
	case fractionTag:
		return p.fraction()
	case complexTag:
		re := p.fraction()
		im := p.fraction()
		return exact.BinaryOp(re, token.ADD, exact.MakeImag(im))
	case stringTag:
		return exact.MakeString(p.string())
	default:
		panic(fmt.Sprintf("unexpected value kind %d", kind))
	}
}

// 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 {
//.........這裏部分代碼省略.........

//.........這裏部分代碼省略.........
			check.recordBuiltinType(call.Fun, makeSig(nil, c))
		}

	case _Complex:
		// complex(x, y realT) complexT
		if !check.complexArg(x) {
			return
		}

		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}
		if !check.complexArg(&y) {
			return
		}

		check.convertUntyped(x, y.typ)
		if x.mode == invalid {
			return
		}
		check.convertUntyped(&y, x.typ)
		if y.mode == invalid {
			return
		}

		if !Identical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			return
		}

		if x.mode == constant && y.mode == constant {
			x.val = exact.BinaryOp(x.val, token.ADD, exact.MakeImag(y.val))
		} else {
			x.mode = value
		}

		realT := x.typ
		complexT := Typ[Invalid]
		switch realT.Underlying().(*Basic).kind {
		case Float32:
			complexT = Typ[Complex64]
		case Float64:
			complexT = Typ[Complex128]
		case UntypedInt, UntypedRune, UntypedFloat:
			if x.mode == constant {
				realT = defaultType(realT).(*Basic)
				complexT = Typ[UntypedComplex]
			} else {
				// untyped but not constant; probably because one
				// operand is a non-constant shift of untyped lhs
				realT = Typ[Float64]
				complexT = Typ[Complex128]
			}
		default:
			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
			return
		}

		x.typ = complexT
		if check.Types != nil && x.mode != constant {
			check.recordBuiltinType(call.Fun, makeSig(complexT, realT, realT))
		}

		if x.mode != constant {

// ConstDecl   = "const" ExportedName [ Type ] "=" Literal .
// Literal     = bool_lit | int_lit | float_lit | complex_lit | rune_lit | string_lit .
// bool_lit    = "true" | "false" .
// complex_lit = "(" float_lit "+" float_lit "i" ")" .
// rune_lit    = "(" int_lit "+" int_lit ")" .
// string_lit  = `"` { unicode_char } `"` .
//
func (p *parser) parseConstDecl() {
	p.expectKeyword("const")
	pkg, name := p.parseExportedName()

	var typ0 types.Type
	if p.tok != '=' {
		typ0 = p.parseType()
	}

	p.expect('=')
	var typ types.Type
	var val exact.Value
	switch p.tok {
	case scanner.Ident:
		// bool_lit
		if p.lit != "true" && p.lit != "false" {
			p.error("expected true or false")
		}
		typ = types.Typ[types.UntypedBool]
		val = exact.MakeBool(p.lit == "true")
		p.next()

	case '-', scanner.Int:
		// int_lit
		typ, val = p.parseNumber()

	case '(':
		// complex_lit or rune_lit
		p.next()
		if p.tok == scanner.Char {
			p.next()
			p.expect('+')
			typ = types.Typ[types.UntypedRune]
			_, val = p.parseNumber()
			p.expect(')')
			break
		}
		_, re := p.parseNumber()
		p.expect('+')
		_, im := p.parseNumber()
		p.expectKeyword("i")
		p.expect(')')
		typ = types.Typ[types.UntypedComplex]
		val = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))

	case scanner.Char:
		// rune_lit
		typ = types.Typ[types.UntypedRune]
		val = exact.MakeFromLiteral(p.lit, token.CHAR)
		p.next()

	case scanner.String:
		// string_lit
		typ = types.Typ[types.UntypedString]
		val = exact.MakeFromLiteral(p.lit, token.STRING)
		p.next()

	default:
		p.errorf("expected literal got %s", scanner.TokenString(p.tok))
	}

	if typ0 == nil {
		typ0 = typ
	}

	pkg.Scope().Insert(types.NewConst(token.NoPos, pkg, name, typ0, val))
}

//.........這裏部分代碼省略.........
		}
		x.mode = novalue

	case _Complex:
		if !check.complexArg(x) {
			goto Error
		}

		var y operand
		check.expr(&y, args[1])
		if y.mode == invalid {
			goto Error
		}
		if !check.complexArg(&y) {
			goto Error
		}

		check.convertUntyped(x, y.typ)
		if x.mode == invalid {
			goto Error
		}
		check.convertUntyped(&y, x.typ)
		if y.mode == invalid {
			goto Error
		}

		if !IsIdentical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			goto Error
		}

		typ := x.typ.Underlying().(*Basic)
		if x.mode == constant && y.mode == constant {
			x.val = exact.BinaryOp(x.val, token.ADD, exact.MakeImag(y.val))
		} else {
			x.mode = value
		}

		switch typ.kind {
		case Float32:
			x.typ = Typ[Complex64]
		case Float64:
			x.typ = Typ[Complex128]
		case UntypedInt, UntypedRune, UntypedFloat:
			if x.mode == constant {
				typ = defaultType(typ).(*Basic)
				x.typ = Typ[UntypedComplex]
			} else {
				// untyped but not constant; probably because one
				// operand is a non-constant shift of untyped lhs
				typ = Typ[Float64]
				x.typ = Typ[Complex128]
			}
		default:
			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
			goto Error
		}

		if x.mode != constant {
			// The arguments have now their final types, which at run-
			// time will be materialized. Update the expression trees.
			// If the current types are untyped, the materialized type
			// is the respective default type.
			// (If the result is constant, the arguments are never
			// materialized and there is nothing to do.)
			check.updateExprType(args[0], typ, true)