summaryrefslogtreecommitdiffstats
path: root/src/go/constant
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--src/go/constant/example_test.go180
-rw-r--r--src/go/constant/value.go1391
-rw-r--r--src/go/constant/value_test.go708
3 files changed, 2279 insertions, 0 deletions
diff --git a/src/go/constant/example_test.go b/src/go/constant/example_test.go
new file mode 100644
index 0000000..6443ee6
--- /dev/null
+++ b/src/go/constant/example_test.go
@@ -0,0 +1,180 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package constant_test
+
+import (
+ "fmt"
+ "go/constant"
+ "go/token"
+ "math"
+ "sort"
+)
+
+func Example_complexNumbers() {
+ // Create the complex number 2.3 + 5i.
+ ar := constant.MakeFloat64(2.3)
+ ai := constant.MakeImag(constant.MakeInt64(5))
+ a := constant.BinaryOp(ar, token.ADD, ai)
+
+ // Compute (2.3 + 5i) * 11.
+ b := constant.MakeUint64(11)
+ c := constant.BinaryOp(a, token.MUL, b)
+
+ // Convert c into a complex128.
+ Ar, exact := constant.Float64Val(constant.Real(c))
+ if !exact {
+ fmt.Printf("Could not represent real part %s exactly as float64\n", constant.Real(c))
+ }
+ Ai, exact := constant.Float64Val(constant.Imag(c))
+ if !exact {
+ fmt.Printf("Could not represent imaginary part %s as exactly as float64\n", constant.Imag(c))
+ }
+ C := complex(Ar, Ai)
+
+ fmt.Println("literal", 25.3+55i)
+ fmt.Println("go/constant", c)
+ fmt.Println("complex128", C)
+
+ // Output:
+ //
+ // Could not represent real part 25.3 exactly as float64
+ // literal (25.3+55i)
+ // go/constant (25.3 + 55i)
+ // complex128 (25.299999999999997+55i)
+}
+
+func ExampleBinaryOp() {
+ // 11 / 0.5
+ a := constant.MakeUint64(11)
+ b := constant.MakeFloat64(0.5)
+ c := constant.BinaryOp(a, token.QUO, b)
+ fmt.Println(c)
+
+ // Output: 22
+}
+
+func ExampleUnaryOp() {
+ vs := []constant.Value{
+ constant.MakeBool(true),
+ constant.MakeFloat64(2.7),
+ constant.MakeUint64(42),
+ }
+
+ for i, v := range vs {
+ switch v.Kind() {
+ case constant.Bool:
+ vs[i] = constant.UnaryOp(token.NOT, v, 0)
+
+ case constant.Float:
+ vs[i] = constant.UnaryOp(token.SUB, v, 0)
+
+ case constant.Int:
+ // Use 16-bit precision.
+ // This would be equivalent to ^uint16(v).
+ vs[i] = constant.UnaryOp(token.XOR, v, 16)
+ }
+ }
+
+ for _, v := range vs {
+ fmt.Println(v)
+ }
+
+ // Output:
+ //
+ // false
+ // -2.7
+ // 65493
+}
+
+func ExampleCompare() {
+ vs := []constant.Value{
+ constant.MakeString("Z"),
+ constant.MakeString("bacon"),
+ constant.MakeString("go"),
+ constant.MakeString("Frame"),
+ constant.MakeString("defer"),
+ constant.MakeFromLiteral(`"a"`, token.STRING, 0),
+ }
+
+ sort.Slice(vs, func(i, j int) bool {
+ // Equivalent to vs[i] <= vs[j].
+ return constant.Compare(vs[i], token.LEQ, vs[j])
+ })
+
+ for _, v := range vs {
+ fmt.Println(constant.StringVal(v))
+ }
+
+ // Output:
+ //
+ // Frame
+ // Z
+ // a
+ // bacon
+ // defer
+ // go
+}
+
+func ExampleSign() {
+ zero := constant.MakeInt64(0)
+ one := constant.MakeInt64(1)
+ negOne := constant.MakeInt64(-1)
+
+ mkComplex := func(a, b constant.Value) constant.Value {
+ b = constant.MakeImag(b)
+ return constant.BinaryOp(a, token.ADD, b)
+ }
+
+ vs := []constant.Value{
+ negOne,
+ mkComplex(zero, negOne),
+ mkComplex(one, negOne),
+ mkComplex(negOne, one),
+ mkComplex(negOne, negOne),
+ zero,
+ mkComplex(zero, zero),
+ one,
+ mkComplex(zero, one),
+ mkComplex(one, one),
+ }
+
+ for _, v := range vs {
+ fmt.Printf("% d %s\n", constant.Sign(v), v)
+ }
+
+ // Output:
+ //
+ // -1 -1
+ // -1 (0 + -1i)
+ // -1 (1 + -1i)
+ // -1 (-1 + 1i)
+ // -1 (-1 + -1i)
+ // 0 0
+ // 0 (0 + 0i)
+ // 1 1
+ // 1 (0 + 1i)
+ // 1 (1 + 1i)
+}
+
+func ExampleVal() {
+ maxint := constant.MakeInt64(math.MaxInt64)
+ fmt.Printf("%v\n", constant.Val(maxint))
+
+ e := constant.MakeFloat64(math.E)
+ fmt.Printf("%v\n", constant.Val(e))
+
+ b := constant.MakeBool(true)
+ fmt.Printf("%v\n", constant.Val(b))
+
+ b = constant.Make(false)
+ fmt.Printf("%v\n", constant.Val(b))
+
+ // Output:
+ //
+ // 9223372036854775807
+ // 6121026514868073/2251799813685248
+ // true
+ // false
+}
diff --git a/src/go/constant/value.go b/src/go/constant/value.go
new file mode 100644
index 0000000..4641442
--- /dev/null
+++ b/src/go/constant/value.go
@@ -0,0 +1,1391 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package constant implements Values representing untyped
+// Go constants and their corresponding operations.
+//
+// A special Unknown value may be used when a value
+// is unknown due to an error. Operations on unknown
+// values produce unknown values unless specified
+// otherwise.
+//
+package constant
+
+import (
+ "fmt"
+ "go/token"
+ "math"
+ "math/big"
+ "strconv"
+ "strings"
+ "sync"
+ "unicode/utf8"
+)
+
+// Kind specifies the kind of value represented by a Value.
+type Kind int
+
+const (
+ // unknown values
+ Unknown Kind = iota
+
+ // non-numeric values
+ Bool
+ String
+
+ // numeric values
+ Int
+ Float
+ Complex
+)
+
+// A Value represents the value of a Go constant.
+type Value interface {
+ // Kind returns the value kind.
+ Kind() Kind
+
+ // String returns a short, quoted (human-readable) form of the value.
+ // For numeric values, the result may be an approximation;
+ // for String values the result may be a shortened string.
+ // Use ExactString for a string representing a value exactly.
+ String() string
+
+ // ExactString returns an exact, quoted (human-readable) form of the value.
+ // If the Value is of Kind String, use StringVal to obtain the unquoted string.
+ ExactString() string
+
+ // Prevent external implementations.
+ implementsValue()
+}
+
+// ----------------------------------------------------------------------------
+// Implementations
+
+// Maximum supported mantissa precision.
+// The spec requires at least 256 bits; typical implementations use 512 bits.
+const prec = 512
+
+// TODO(gri) Consider storing "error" information in an unknownVal so clients
+// can provide better error messages. For instance, if a number is
+// too large (incl. infinity), that could be recorded in unknownVal.
+// See also #20583 and #42695 for use cases.
+
+type (
+ unknownVal struct{}
+ boolVal bool
+ stringVal struct {
+ // Lazy value: either a string (l,r==nil) or an addition (l,r!=nil).
+ mu sync.Mutex
+ s string
+ l, r *stringVal
+ }
+ int64Val int64 // Int values representable as an int64
+ intVal struct{ val *big.Int } // Int values not representable as an int64
+ ratVal struct{ val *big.Rat } // Float values representable as a fraction
+ floatVal struct{ val *big.Float } // Float values not representable as a fraction
+ complexVal struct{ re, im Value }
+)
+
+func (unknownVal) Kind() Kind { return Unknown }
+func (boolVal) Kind() Kind { return Bool }
+func (*stringVal) Kind() Kind { return String }
+func (int64Val) Kind() Kind { return Int }
+func (intVal) Kind() Kind { return Int }
+func (ratVal) Kind() Kind { return Float }
+func (floatVal) Kind() Kind { return Float }
+func (complexVal) Kind() Kind { return Complex }
+
+func (unknownVal) String() string { return "unknown" }
+func (x boolVal) String() string { return strconv.FormatBool(bool(x)) }
+
+// String returns a possibly shortened quoted form of the String value.
+func (x *stringVal) String() string {
+ const maxLen = 72 // a reasonable length
+ s := strconv.Quote(x.string())
+ if utf8.RuneCountInString(s) > maxLen {
+ // The string without the enclosing quotes is greater than maxLen-2 runes
+ // long. Remove the last 3 runes (including the closing '"') by keeping
+ // only the first maxLen-3 runes; then add "...".
+ i := 0
+ for n := 0; n < maxLen-3; n++ {
+ _, size := utf8.DecodeRuneInString(s[i:])
+ i += size
+ }
+ s = s[:i] + "..."
+ }
+ return s
+}
+
+// string constructs and returns the actual string literal value.
+// If x represents an addition, then it rewrites x to be a single
+// string, to speed future calls. This lazy construction avoids
+// building different string values for all subpieces of a large
+// concatenation. See golang.org/issue/23348.
+func (x *stringVal) string() string {
+ x.mu.Lock()
+ if x.l != nil {
+ x.s = strings.Join(reverse(x.appendReverse(nil)), "")
+ x.l = nil
+ x.r = nil
+ }
+ s := x.s
+ x.mu.Unlock()
+
+ return s
+}
+
+// reverse reverses x in place and returns it.
+func reverse(x []string) []string {
+ n := len(x)
+ for i := 0; i+i < n; i++ {
+ x[i], x[n-1-i] = x[n-1-i], x[i]
+ }
+ return x
+}
+
+// appendReverse appends to list all of x's subpieces, but in reverse,
+// and returns the result. Appending the reversal allows processing
+// the right side in a recursive call and the left side in a loop.
+// Because a chain like a + b + c + d + e is actually represented
+// as ((((a + b) + c) + d) + e), the left-side loop avoids deep recursion.
+// x must be locked.
+func (x *stringVal) appendReverse(list []string) []string {
+ y := x
+ for y.r != nil {
+ y.r.mu.Lock()
+ list = y.r.appendReverse(list)
+ y.r.mu.Unlock()
+
+ l := y.l
+ if y != x {
+ y.mu.Unlock()
+ }
+ l.mu.Lock()
+ y = l
+ }
+ s := y.s
+ if y != x {
+ y.mu.Unlock()
+ }
+ return append(list, s)
+}
+
+func (x int64Val) String() string { return strconv.FormatInt(int64(x), 10) }
+func (x intVal) String() string { return x.val.String() }
+func (x ratVal) String() string { return rtof(x).String() }
+
+// String returns a decimal approximation of the Float value.
+func (x floatVal) String() string {
+ f := x.val
+
+ // Don't try to convert infinities (will not terminate).
+ if f.IsInf() {
+ return f.String()
+ }
+
+ // Use exact fmt formatting if in float64 range (common case):
+ // proceed if f doesn't underflow to 0 or overflow to inf.
+ if x, _ := f.Float64(); f.Sign() == 0 == (x == 0) && !math.IsInf(x, 0) {
+ return fmt.Sprintf("%.6g", x)
+ }
+
+ // Out of float64 range. Do approximate manual to decimal
+ // conversion to avoid precise but possibly slow Float
+ // formatting.
+ // f = mant * 2**exp
+ var mant big.Float
+ exp := f.MantExp(&mant) // 0.5 <= |mant| < 1.0
+
+ // approximate float64 mantissa m and decimal exponent d
+ // f ~ m * 10**d
+ m, _ := mant.Float64() // 0.5 <= |m| < 1.0
+ d := float64(exp) * (math.Ln2 / math.Ln10) // log_10(2)
+
+ // adjust m for truncated (integer) decimal exponent e
+ e := int64(d)
+ m *= math.Pow(10, d-float64(e))
+
+ // ensure 1 <= |m| < 10
+ switch am := math.Abs(m); {
+ case am < 1-0.5e-6:
+ // The %.6g format below rounds m to 5 digits after the
+ // decimal point. Make sure that m*10 < 10 even after
+ // rounding up: m*10 + 0.5e-5 < 10 => m < 1 - 0.5e6.
+ m *= 10
+ e--
+ case am >= 10:
+ m /= 10
+ e++
+ }
+
+ return fmt.Sprintf("%.6ge%+d", m, e)
+}
+
+func (x complexVal) String() string { return fmt.Sprintf("(%s + %si)", x.re, x.im) }
+
+func (x unknownVal) ExactString() string { return x.String() }
+func (x boolVal) ExactString() string { return x.String() }
+func (x *stringVal) ExactString() string { return strconv.Quote(x.string()) }
+func (x int64Val) ExactString() string { return x.String() }
+func (x intVal) ExactString() string { return x.String() }
+
+func (x ratVal) ExactString() string {
+ r := x.val
+ if r.IsInt() {
+ return r.Num().String()
+ }
+ return r.String()
+}
+
+func (x floatVal) ExactString() string { return x.val.Text('p', 0) }
+
+func (x complexVal) ExactString() string {
+ return fmt.Sprintf("(%s + %si)", x.re.ExactString(), x.im.ExactString())
+}
+
+func (unknownVal) implementsValue() {}
+func (boolVal) implementsValue() {}
+func (*stringVal) implementsValue() {}
+func (int64Val) implementsValue() {}
+func (ratVal) implementsValue() {}
+func (intVal) implementsValue() {}
+func (floatVal) implementsValue() {}
+func (complexVal) implementsValue() {}
+
+func newInt() *big.Int { return new(big.Int) }
+func newRat() *big.Rat { return new(big.Rat) }
+func newFloat() *big.Float { return new(big.Float).SetPrec(prec) }
+
+func i64toi(x int64Val) intVal { return intVal{newInt().SetInt64(int64(x))} }
+func i64tor(x int64Val) ratVal { return ratVal{newRat().SetInt64(int64(x))} }
+func i64tof(x int64Val) floatVal { return floatVal{newFloat().SetInt64(int64(x))} }
+func itor(x intVal) ratVal { return ratVal{newRat().SetInt(x.val)} }
+func itof(x intVal) floatVal { return floatVal{newFloat().SetInt(x.val)} }
+
+func rtof(x ratVal) floatVal {
+ a := newFloat().SetInt(x.val.Num())
+ b := newFloat().SetInt(x.val.Denom())
+ return floatVal{a.Quo(a, b)}
+}
+
+func vtoc(x Value) complexVal { return complexVal{x, int64Val(0)} }
+
+func makeInt(x *big.Int) Value {
+ if x.IsInt64() {
+ return int64Val(x.Int64())
+ }
+ return intVal{x}
+}
+
+// Permit fractions with component sizes up to maxExp
+// before switching to using floating-point numbers.
+const maxExp = 4 << 10
+
+func makeRat(x *big.Rat) Value {
+ a := x.Num()
+ b := x.Denom()
+ if a.BitLen() < maxExp && b.BitLen() < maxExp {
+ // ok to remain fraction
+ return ratVal{x}
+ }
+ // components too large => switch to float
+ fa := newFloat().SetInt(a)
+ fb := newFloat().SetInt(b)
+ return floatVal{fa.Quo(fa, fb)}
+}
+
+var floatVal0 = floatVal{newFloat()}
+
+func makeFloat(x *big.Float) Value {
+ // convert -0
+ if x.Sign() == 0 {
+ return floatVal0
+ }
+ if x.IsInf() {
+ return unknownVal{}
+ }
+ return floatVal{x}
+}
+
+func makeComplex(re, im Value) Value {
+ if re.Kind() == Unknown || im.Kind() == Unknown {
+ return unknownVal{}
+ }
+ return complexVal{re, im}
+}
+
+func makeFloatFromLiteral(lit string) Value {
+ if f, ok := newFloat().SetString(lit); ok {
+ if smallRat(f) {
+ // ok to use rationals
+ if f.Sign() == 0 {
+ // Issue 20228: If the float underflowed to zero, parse just "0".
+ // Otherwise, lit might contain a value with a large negative exponent,
+ // such as -6e-1886451601. As a float, that will underflow to 0,
+ // but it'll take forever to parse as a Rat.
+ lit = "0"
+ }
+ if r, ok := newRat().SetString(lit); ok {
+ return ratVal{r}
+ }
+ }
+ // otherwise use floats
+ return makeFloat(f)
+ }
+ return nil
+}
+
+// smallRat reports whether x would lead to "reasonably"-sized fraction
+// if converted to a *big.Rat.
+func smallRat(x *big.Float) bool {
+ if !x.IsInf() {
+ e := x.MantExp(nil)
+ return -maxExp < e && e < maxExp
+ }
+ return false
+}
+
+// ----------------------------------------------------------------------------
+// Factories
+
+// MakeUnknown returns the Unknown value.
+func MakeUnknown() Value { return unknownVal{} }
+
+// MakeBool returns the Bool value for b.
+func MakeBool(b bool) Value { return boolVal(b) }
+
+// MakeString returns the String value for s.
+func MakeString(s string) Value { return &stringVal{s: s} }
+
+// MakeInt64 returns the Int value for x.
+func MakeInt64(x int64) Value { return int64Val(x) }
+
+// MakeUint64 returns the Int value for x.
+func MakeUint64(x uint64) Value {
+ if x < 1<<63 {
+ return int64Val(int64(x))
+ }
+ return intVal{newInt().SetUint64(x)}
+}
+
+// MakeFloat64 returns the Float value for x.
+// If x is -0.0, the result is 0.0.
+// If x is not finite, the result is an Unknown.
+func MakeFloat64(x float64) Value {
+ if math.IsInf(x, 0) || math.IsNaN(x) {
+ return unknownVal{}
+ }
+ return ratVal{newRat().SetFloat64(x + 0)} // convert -0 to 0
+}
+
+// MakeFromLiteral returns the corresponding integer, floating-point,
+// imaginary, character, or string value for a Go literal string. The
+// tok value must be one of token.INT, token.FLOAT, token.IMAG,
+// token.CHAR, or token.STRING. The final argument must be zero.
+// If the literal string syntax is invalid, the result is an Unknown.
+func MakeFromLiteral(lit string, tok token.Token, zero uint) Value {
+ if zero != 0 {
+ panic("MakeFromLiteral called with non-zero last argument")
+ }
+
+ switch tok {
+ case token.INT:
+ if x, err := strconv.ParseInt(lit, 0, 64); err == nil {
+ return int64Val(x)
+ }
+ if x, ok := newInt().SetString(lit, 0); ok {
+ return intVal{x}
+ }
+
+ case token.FLOAT:
+ if x := makeFloatFromLiteral(lit); x != nil {
+ return x
+ }
+
+ case token.IMAG:
+ if n := len(lit); n > 0 && lit[n-1] == 'i' {
+ if im := makeFloatFromLiteral(lit[:n-1]); im != nil {
+ return makeComplex(int64Val(0), im)
+ }
+ }
+
+ case token.CHAR:
+ if n := len(lit); n >= 2 {
+ if code, _, _, err := strconv.UnquoteChar(lit[1:n-1], '\''); err == nil {
+ return MakeInt64(int64(code))
+ }
+ }
+
+ case token.STRING:
+ if s, err := strconv.Unquote(lit); err == nil {
+ return MakeString(s)
+ }
+
+ default:
+ panic(fmt.Sprintf("%v is not a valid token", tok))
+ }
+
+ return unknownVal{}
+}
+
+// ----------------------------------------------------------------------------
+// Accessors
+//
+// For unknown arguments the result is the zero value for the respective
+// accessor type, except for Sign, where the result is 1.
+
+// BoolVal returns the Go boolean value of x, which must be a Bool or an Unknown.
+// If x is Unknown, the result is false.
+func BoolVal(x Value) bool {
+ switch x := x.(type) {
+ case boolVal:
+ return bool(x)
+ case unknownVal:
+ return false
+ default:
+ panic(fmt.Sprintf("%v not a Bool", x))
+ }
+}
+
+// StringVal returns the Go string value of x, which must be a String or an Unknown.
+// If x is Unknown, the result is "".
+func StringVal(x Value) string {
+ switch x := x.(type) {
+ case *stringVal:
+ return x.string()
+ case unknownVal:
+ return ""
+ default:
+ panic(fmt.Sprintf("%v not a String", x))
+ }
+}
+
+// Int64Val returns the Go int64 value of x and whether the result is exact;
+// x must be an Int or an Unknown. If the result is not exact, its value is undefined.
+// If x is Unknown, the result is (0, false).
+func Int64Val(x Value) (int64, bool) {
+ switch x := x.(type) {
+ case int64Val:
+ return int64(x), true
+ case intVal:
+ return x.val.Int64(), false // not an int64Val and thus not exact
+ case unknownVal:
+ return 0, false
+ default:
+ panic(fmt.Sprintf("%v not an Int", x))
+ }
+}
+
+// Uint64Val returns the Go uint64 value of x and whether the result is exact;
+// x must be an Int or an Unknown. If the result is not exact, its value is undefined.
+// If x is Unknown, the result is (0, false).
+func Uint64Val(x Value) (uint64, bool) {
+ switch x := x.(type) {
+ case int64Val:
+ return uint64(x), x >= 0
+ case intVal:
+ return x.val.Uint64(), x.val.IsUint64()
+ case unknownVal:
+ return 0, false
+ default:
+ panic(fmt.Sprintf("%v not an Int", x))
+ }
+}
+
+// Float32Val is like Float64Val but for float32 instead of float64.
+func Float32Val(x Value) (float32, bool) {
+ switch x := x.(type) {
+ case int64Val:
+ f := float32(x)
+ return f, int64Val(f) == x
+ case intVal:
+ f, acc := newFloat().SetInt(x.val).Float32()
+ return f, acc == big.Exact
+ case ratVal:
+ return x.val.Float32()
+ case floatVal:
+ f, acc := x.val.Float32()
+ return f, acc == big.Exact
+ case unknownVal:
+ return 0, false
+ default:
+ panic(fmt.Sprintf("%v not a Float", x))
+ }
+}
+
+// Float64Val returns the nearest Go float64 value of x and whether the result is exact;
+// x must be numeric or an Unknown, but not Complex. For values too small (too close to 0)
+// to represent as float64, Float64Val silently underflows to 0. The result sign always
+// matches the sign of x, even for 0.
+// If x is Unknown, the result is (0, false).
+func Float64Val(x Value) (float64, bool) {
+ switch x := x.(type) {
+ case int64Val:
+ f := float64(int64(x))
+ return f, int64Val(f) == x
+ case intVal:
+ f, acc := newFloat().SetInt(x.val).Float64()
+ return f, acc == big.Exact
+ case ratVal:
+ return x.val.Float64()
+ case floatVal:
+ f, acc := x.val.Float64()
+ return f, acc == big.Exact
+ case unknownVal:
+ return 0, false
+ default:
+ panic(fmt.Sprintf("%v not a Float", x))
+ }
+}
+
+// Val returns the underlying value for a given constant. Since it returns an
+// interface, it is up to the caller to type assert the result to the expected
+// type. The possible dynamic return types are:
+//
+// x Kind type of result
+// -----------------------------------------
+// Bool bool
+// String string
+// Int int64 or *big.Int
+// Float *big.Float or *big.Rat
+// everything else nil
+//
+func Val(x Value) interface{} {
+ switch x := x.(type) {
+ case boolVal:
+ return bool(x)
+ case *stringVal:
+ return x.string()
+ case int64Val:
+ return int64(x)
+ case intVal:
+ return x.val
+ case ratVal:
+ return x.val
+ case floatVal:
+ return x.val
+ default:
+ return nil
+ }
+}
+
+// Make returns the Value for x.
+//
+// type of x result Kind
+// ----------------------------
+// bool Bool
+// string String
+// int64 Int
+// *big.Int Int
+// *big.Float Float
+// *big.Rat Float
+// anything else Unknown
+//
+func Make(x interface{}) Value {
+ switch x := x.(type) {
+ case bool:
+ return boolVal(x)
+ case string:
+ return &stringVal{s: x}
+ case int64:
+ return int64Val(x)
+ case *big.Int:
+ return makeInt(x)
+ case *big.Rat:
+ return makeRat(x)
+ case *big.Float:
+ return makeFloat(x)
+ default:
+ return unknownVal{}
+ }
+}
+
+// BitLen returns the number of bits required to represent
+// the absolute value x in binary representation; x must be an Int or an Unknown.
+// If x is Unknown, the result is 0.
+func BitLen(x Value) int {
+ switch x := x.(type) {
+ case int64Val:
+ return i64toi(x).val.BitLen()
+ case intVal:
+ return x.val.BitLen()
+ case unknownVal:
+ return 0
+ default:
+ panic(fmt.Sprintf("%v not an Int", x))
+ }
+}
+
+// Sign returns -1, 0, or 1 depending on whether x < 0, x == 0, or x > 0;
+// x must be numeric or Unknown. For complex values x, the sign is 0 if x == 0,
+// otherwise it is != 0. If x is Unknown, the result is 1.
+func Sign(x Value) int {
+ switch x := x.(type) {
+ case int64Val:
+ switch {
+ case x < 0:
+ return -1
+ case x > 0:
+ return 1
+ }
+ return 0
+ case intVal:
+ return x.val.Sign()
+ case ratVal:
+ return x.val.Sign()
+ case floatVal:
+ return x.val.Sign()
+ case complexVal:
+ return Sign(x.re) | Sign(x.im)
+ case unknownVal:
+ return 1 // avoid spurious division by zero errors
+ default:
+ panic(fmt.Sprintf("%v not numeric", x))
+ }
+}
+
+// ----------------------------------------------------------------------------
+// Support for assembling/disassembling numeric values
+
+const (
+ // Compute the size of a Word in bytes.
+ _m = ^big.Word(0)
+ _log = _m>>8&1 + _m>>16&1 + _m>>32&1
+ wordSize = 1 << _log
+)
+
+// Bytes returns the bytes for the absolute value of x in little-
+// endian binary representation; x must be an Int.
+func Bytes(x Value) []byte {
+ var t intVal
+ switch x := x.(type) {
+ case int64Val:
+ t = i64toi(x)
+ case intVal:
+ t = x
+ default:
+ panic(fmt.Sprintf("%v not an Int", x))
+ }
+
+ words := t.val.Bits()
+ bytes := make([]byte, len(words)*wordSize)
+
+ i := 0
+ for _, w := range words {
+ for j := 0; j < wordSize; j++ {
+ bytes[i] = byte(w)
+ w >>= 8
+ i++
+ }
+ }
+ // remove leading 0's
+ for i > 0 && bytes[i-1] == 0 {
+ i--
+ }
+
+ return bytes[:i]
+}
+
+// MakeFromBytes returns the Int value given the bytes of its little-endian
+// binary representation. An empty byte slice argument represents 0.
+func MakeFromBytes(bytes []byte) Value {
+ words := make([]big.Word, (len(bytes)+(wordSize-1))/wordSize)
+
+ i := 0
+ var w big.Word
+ var s uint
+ for _, b := range bytes {
+ w |= big.Word(b) << s
+ if s += 8; s == wordSize*8 {
+ words[i] = w
+ i++
+ w = 0
+ s = 0
+ }
+ }
+ // store last word
+ if i < len(words) {
+ words[i] = w
+ i++
+ }
+ // remove leading 0's
+ for i > 0 && words[i-1] == 0 {
+ i--
+ }
+
+ return makeInt(newInt().SetBits(words[:i]))
+}
+
+// Num returns the numerator of x; x must be Int, Float, or Unknown.
+// If x is Unknown, or if it is too large or small to represent as a
+// fraction, the result is Unknown. Otherwise the result is an Int
+// with the same sign as x.
+func Num(x Value) Value {
+ switch x := x.(type) {
+ case int64Val, intVal:
+ return x
+ case ratVal:
+ return makeInt(x.val.Num())
+ case floatVal:
+ if smallRat(x.val) {
+ r, _ := x.val.Rat(nil)
+ return makeInt(r.Num())
+ }
+ case unknownVal:
+ break
+ default:
+ panic(fmt.Sprintf("%v not Int or Float", x))
+ }
+ return unknownVal{}
+}
+
+// Denom returns the denominator of x; x must be Int, Float, or Unknown.
+// If x is Unknown, or if it is too large or small to represent as a
+// fraction, the result is Unknown. Otherwise the result is an Int >= 1.
+func Denom(x Value) Value {
+ switch x := x.(type) {
+ case int64Val, intVal:
+ return int64Val(1)
+ case ratVal:
+ return makeInt(x.val.Denom())
+ case floatVal:
+ if smallRat(x.val) {
+ r, _ := x.val.Rat(nil)
+ return makeInt(r.Denom())
+ }
+ case unknownVal:
+ break
+ default:
+ panic(fmt.Sprintf("%v not Int or Float", x))
+ }
+ return unknownVal{}
+}
+
+// MakeImag returns the Complex value x*i;
+// x must be Int, Float, or Unknown.
+// If x is Unknown, the result is Unknown.
+func MakeImag(x Value) Value {
+ switch x.(type) {
+ case unknownVal:
+ return x
+ case int64Val, intVal, ratVal, floatVal:
+ return makeComplex(int64Val(0), x)
+ default:
+ panic(fmt.Sprintf("%v not Int or Float", x))
+ }
+}
+
+// Real returns the real part of x, which must be a numeric or unknown value.
+// If x is Unknown, the result is Unknown.
+func Real(x Value) Value {
+ switch x := x.(type) {
+ case unknownVal, int64Val, intVal, ratVal, floatVal:
+ return x
+ case complexVal:
+ return x.re
+ default:
+ panic(fmt.Sprintf("%v not numeric", x))
+ }
+}
+
+// Imag returns the imaginary part of x, which must be a numeric or unknown value.
+// If x is Unknown, the result is Unknown.
+func Imag(x Value) Value {
+ switch x := x.(type) {
+ case unknownVal:
+ return x
+ case int64Val, intVal, ratVal, floatVal:
+ return int64Val(0)
+ case complexVal:
+ return x.im
+ default:
+ panic(fmt.Sprintf("%v not numeric", x))
+ }
+}
+
+// ----------------------------------------------------------------------------
+// Numeric conversions
+
+// ToInt converts x to an Int value if x is representable as an Int.
+// Otherwise it returns an Unknown.
+func ToInt(x Value) Value {
+ switch x := x.(type) {
+ case int64Val, intVal:
+ return x
+
+ case ratVal:
+ if x.val.IsInt() {
+ return makeInt(x.val.Num())
+ }
+
+ case floatVal:
+ // avoid creation of huge integers
+ // (Existing tests require permitting exponents of at least 1024;
+ // allow any value that would also be permissible as a fraction.)
+ if smallRat(x.val) {
+ i := newInt()
+ if _, acc := x.val.Int(i); acc == big.Exact {
+ return makeInt(i)
+ }
+
+ // If we can get an integer by rounding up or down,
+ // assume x is not an integer because of rounding
+ // errors in prior computations.
+
+ const delta = 4 // a small number of bits > 0
+ var t big.Float
+ t.SetPrec(prec - delta)
+
+ // try rounding down a little
+ t.SetMode(big.ToZero)
+ t.Set(x.val)
+ if _, acc := t.Int(i); acc == big.Exact {
+ return makeInt(i)
+ }
+
+ // try rounding up a little
+ t.SetMode(big.AwayFromZero)
+ t.Set(x.val)
+ if _, acc := t.Int(i); acc == big.Exact {
+ return makeInt(i)
+ }
+ }
+
+ case complexVal:
+ if re := ToFloat(x); re.Kind() == Float {
+ return ToInt(re)
+ }
+ }
+
+ return unknownVal{}
+}
+
+// ToFloat converts x to a Float value if x is representable as a Float.
+// Otherwise it returns an Unknown.
+func ToFloat(x Value) Value {
+ switch x := x.(type) {
+ case int64Val:
+ return i64tof(x)
+ case intVal:
+ return itof(x)
+ case ratVal, floatVal:
+ return x
+ case complexVal:
+ if im := ToInt(x.im); im.Kind() == Int && Sign(im) == 0 {
+ // imaginary component is 0
+ return ToFloat(x.re)
+ }
+ }
+ return unknownVal{}
+}
+
+// ToComplex converts x to a Complex value if x is representable as a Complex.
+// Otherwise it returns an Unknown.
+func ToComplex(x Value) Value {
+ switch x := x.(type) {
+ case int64Val:
+ return vtoc(i64tof(x))
+ case intVal:
+ return vtoc(itof(x))
+ case ratVal:
+ return vtoc(x)
+ case floatVal:
+ return vtoc(x)
+ case complexVal:
+ return x
+ }
+ return unknownVal{}
+}
+
+// ----------------------------------------------------------------------------
+// Operations
+
+// is32bit reports whether x can be represented using 32 bits.
+func is32bit(x int64) bool {
+ const s = 32
+ return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+}
+
+// is63bit reports whether x can be represented using 63 bits.
+func is63bit(x int64) bool {
+ const s = 63
+ return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+}
+
+// UnaryOp returns the result of the unary expression op y.
+// The operation must be defined for the operand.
+// If prec > 0 it specifies the ^ (xor) result size in bits.
+// If y is Unknown, the result is Unknown.
+//
+func UnaryOp(op token.Token, y Value, prec uint) Value {
+ switch op {
+ case token.ADD:
+ switch y.(type) {
+ case unknownVal, int64Val, intVal, ratVal, floatVal, complexVal:
+ return y
+ }
+
+ case token.SUB:
+ switch y := y.(type) {
+ case unknownVal:
+ return y
+ case int64Val:
+ if z := -y; z != y {
+ return z // no overflow
+ }
+ return makeInt(newInt().Neg(big.NewInt(int64(y))))
+ case intVal:
+ return makeInt(newInt().Neg(y.val))
+ case ratVal:
+ return makeRat(newRat().Neg(y.val))
+ case floatVal:
+ return makeFloat(newFloat().Neg(y.val))
+ case complexVal:
+ re := UnaryOp(token.SUB, y.re, 0)
+ im := UnaryOp(token.SUB, y.im, 0)
+ return makeComplex(re, im)
+ }
+
+ case token.XOR:
+ z := newInt()
+ switch y := y.(type) {
+ case unknownVal:
+ return y
+ case int64Val:
+ z.Not(big.NewInt(int64(y)))
+ case intVal:
+ z.Not(y.val)
+ default:
+ goto Error
+ }
+ // For unsigned types, the result will be negative and
+ // thus "too large": We must limit the result precision
+ // to the type's precision.
+ if prec > 0 {
+ z.AndNot(z, newInt().Lsh(big.NewInt(-1), prec)) // z &^= (-1)<<prec
+ }
+ return makeInt(z)
+
+ case token.NOT:
+ switch y := y.(type) {
+ case unknownVal:
+ return y
+ case boolVal:
+ return !y
+ }
+ }
+
+Error:
+ panic(fmt.Sprintf("invalid unary operation %s%v", op, y))
+}
+
+func ord(x Value) int {
+ switch x.(type) {
+ default:
+ // force invalid value into "x position" in match
+ // (don't panic here so that callers can provide a better error message)
+ return -1
+ case unknownVal:
+ return 0
+ case boolVal, *stringVal:
+ return 1
+ case int64Val:
+ return 2
+ case intVal:
+ return 3
+ case ratVal:
+ return 4
+ case floatVal:
+ return 5
+ case complexVal:
+ return 6
+ }
+}
+
+// match returns the matching representation (same type) with the
+// smallest complexity for two values x and y. If one of them is
+// numeric, both of them must be numeric. If one of them is Unknown
+// or invalid (say, nil) both results are that value.
+//
+func match(x, y Value) (_, _ Value) {
+ if ord(x) > ord(y) {
+ y, x = match(y, x)
+ return x, y
+ }
+ // ord(x) <= ord(y)
+
+ switch x := x.(type) {
+ case boolVal, *stringVal, complexVal:
+ return x, y
+
+ case int64Val:
+ switch y := y.(type) {
+ case int64Val:
+ return x, y
+ case intVal:
+ return i64toi(x), y
+ case ratVal:
+ return i64tor(x), y
+ case floatVal:
+ return i64tof(x), y
+ case complexVal:
+ return vtoc(x), y
+ }
+
+ case intVal:
+ switch y := y.(type) {
+ case intVal:
+ return x, y
+ case ratVal:
+ return itor(x), y
+ case floatVal:
+ return itof(x), y
+ case complexVal:
+ return vtoc(x), y
+ }
+
+ case ratVal:
+ switch y := y.(type) {
+ case ratVal:
+ return x, y
+ case floatVal:
+ return rtof(x), y
+ case complexVal:
+ return vtoc(x), y
+ }
+
+ case floatVal:
+ switch y := y.(type) {
+ case floatVal:
+ return x, y
+ case complexVal:
+ return vtoc(x), y
+ }
+ }
+
+ // force unknown and invalid values into "x position" in callers of match
+ // (don't panic here so that callers can provide a better error message)
+ return x, x
+}
+
+// BinaryOp returns the result of the binary expression x op y.
+// The operation must be defined for the operands. If one of the
+// operands is Unknown, the result is Unknown.
+// BinaryOp doesn't handle comparisons or shifts; use Compare
+// or Shift instead.
+//
+// To force integer division of Int operands, use op == token.QUO_ASSIGN
+// instead of token.QUO; the result is guaranteed to be Int in this case.
+// Division by zero leads to a run-time panic.
+//
+func BinaryOp(x_ Value, op token.Token, y_ Value) Value {
+ x, y := match(x_, y_)
+
+ switch x := x.(type) {
+ case unknownVal:
+ return x
+
+ case boolVal:
+ y := y.(boolVal)
+ switch op {
+ case token.LAND:
+ return x && y
+ case token.LOR:
+ return x || y
+ }
+
+ case int64Val:
+ a := int64(x)
+ b := int64(y.(int64Val))
+ var c int64
+ switch op {
+ case token.ADD:
+ if !is63bit(a) || !is63bit(b) {
+ return makeInt(newInt().Add(big.NewInt(a), big.NewInt(b)))
+ }
+ c = a + b
+ case token.SUB:
+ if !is63bit(a) || !is63bit(b) {
+ return makeInt(newInt().Sub(big.NewInt(a), big.NewInt(b)))
+ }
+ c = a - b
+ case token.MUL:
+ if !is32bit(a) || !is32bit(b) {
+ return makeInt(newInt().Mul(big.NewInt(a), big.NewInt(b)))
+ }
+ c = a * b
+ case token.QUO:
+ return makeRat(big.NewRat(a, b))
+ case token.QUO_ASSIGN: // force integer division
+ c = a / b
+ case token.REM:
+ c = a % b
+ case token.AND:
+ c = a & b
+ case token.OR:
+ c = a | b
+ case token.XOR:
+ c = a ^ b
+ case token.AND_NOT:
+ c = a &^ b
+ default:
+ goto Error
+ }
+ return int64Val(c)
+
+ case intVal:
+ a := x.val
+ b := y.(intVal).val
+ c := newInt()
+ switch op {
+ case token.ADD:
+ c.Add(a, b)
+ case token.SUB:
+ c.Sub(a, b)
+ case token.MUL:
+ c.Mul(a, b)
+ case token.QUO:
+ return makeRat(newRat().SetFrac(a, b))
+ case token.QUO_ASSIGN: // force integer division
+ c.Quo(a, b)
+ case token.REM:
+ c.Rem(a, b)
+ case token.AND:
+ c.And(a, b)
+ case token.OR:
+ c.Or(a, b)
+ case token.XOR:
+ c.Xor(a, b)
+ case token.AND_NOT:
+ c.AndNot(a, b)
+ default:
+ goto Error
+ }
+ return makeInt(c)
+
+ case ratVal:
+ a := x.val
+ b := y.(ratVal).val
+ c := newRat()
+ switch op {
+ case token.ADD:
+ c.Add(a, b)
+ case token.SUB:
+ c.Sub(a, b)
+ case token.MUL:
+ c.Mul(a, b)
+ case token.QUO:
+ c.Quo(a, b)
+ default:
+ goto Error
+ }
+ return makeRat(c)
+
+ case floatVal:
+ a := x.val
+ b := y.(floatVal).val
+ c := newFloat()
+ switch op {
+ case token.ADD:
+ c.Add(a, b)
+ case token.SUB:
+ c.Sub(a, b)
+ case token.MUL:
+ c.Mul(a, b)
+ case token.QUO:
+ c.Quo(a, b)
+ default:
+ goto Error
+ }
+ return makeFloat(c)
+
+ case complexVal:
+ y := y.(complexVal)
+ a, b := x.re, x.im
+ c, d := y.re, y.im
+ var re, im Value
+ switch op {
+ case token.ADD:
+ // (a+c) + i(b+d)
+ re = add(a, c)
+ im = add(b, d)
+ case token.SUB:
+ // (a-c) + i(b-d)
+ re = sub(a, c)
+ im = sub(b, d)
+ case token.MUL:
+ // (ac-bd) + i(bc+ad)
+ ac := mul(a, c)
+ bd := mul(b, d)
+ bc := mul(b, c)
+ ad := mul(a, d)
+ re = sub(ac, bd)
+ im = add(bc, ad)
+ case token.QUO:
+ // (ac+bd)/s + i(bc-ad)/s, with s = cc + dd
+ ac := mul(a, c)
+ bd := mul(b, d)
+ bc := mul(b, c)
+ ad := mul(a, d)
+ cc := mul(c, c)
+ dd := mul(d, d)
+ s := add(cc, dd)
+ re = add(ac, bd)
+ re = quo(re, s)
+ im = sub(bc, ad)
+ im = quo(im, s)
+ default:
+ goto Error
+ }
+ return makeComplex(re, im)
+
+ case *stringVal:
+ if op == token.ADD {
+ return &stringVal{l: x, r: y.(*stringVal)}
+ }
+ }
+
+Error:
+ panic(fmt.Sprintf("invalid binary operation %v %s %v", x_, op, y_))
+}
+
+func add(x, y Value) Value { return BinaryOp(x, token.ADD, y) }
+func sub(x, y Value) Value { return BinaryOp(x, token.SUB, y) }
+func mul(x, y Value) Value { return BinaryOp(x, token.MUL, y) }
+func quo(x, y Value) Value { return BinaryOp(x, token.QUO, y) }
+
+// Shift returns the result of the shift expression x op s
+// with op == token.SHL or token.SHR (<< or >>). x must be
+// an Int or an Unknown. If x is Unknown, the result is x.
+//
+func Shift(x Value, op token.Token, s uint) Value {
+ switch x := x.(type) {
+ case unknownVal:
+ return x
+
+ case int64Val:
+ if s == 0 {
+ return x
+ }
+ switch op {
+ case token.SHL:
+ z := i64toi(x).val
+ return makeInt(z.Lsh(z, s))
+ case token.SHR:
+ return x >> s
+ }
+
+ case intVal:
+ if s == 0 {
+ return x
+ }
+ z := newInt()
+ switch op {
+ case token.SHL:
+ return makeInt(z.Lsh(x.val, s))
+ case token.SHR:
+ return makeInt(z.Rsh(x.val, s))
+ }
+ }
+
+ panic(fmt.Sprintf("invalid shift %v %s %d", x, op, s))
+}
+
+func cmpZero(x int, op token.Token) bool {
+ switch op {
+ case token.EQL:
+ return x == 0
+ case token.NEQ:
+ return x != 0
+ case token.LSS:
+ return x < 0
+ case token.LEQ:
+ return x <= 0
+ case token.GTR:
+ return x > 0
+ case token.GEQ:
+ return x >= 0
+ }
+ panic(fmt.Sprintf("invalid comparison %v %s 0", x, op))
+}
+
+// Compare returns the result of the comparison x op y.
+// The comparison must be defined for the operands.
+// If one of the operands is Unknown, the result is
+// false.
+//
+func Compare(x_ Value, op token.Token, y_ Value) bool {
+ x, y := match(x_, y_)
+
+ switch x := x.(type) {
+ case unknownVal:
+ return false
+
+ case boolVal:
+ y := y.(boolVal)
+ switch op {
+ case token.EQL:
+ return x == y
+ case token.NEQ:
+ return x != y
+ }
+
+ case int64Val:
+ y := y.(int64Val)
+ switch op {
+ case token.EQL:
+ return x == y
+ case token.NEQ:
+ return x != y
+ case token.LSS:
+ return x < y
+ case token.LEQ:
+ return x <= y
+ case token.GTR:
+ return x > y
+ case token.GEQ:
+ return x >= y
+ }
+
+ case intVal:
+ return cmpZero(x.val.Cmp(y.(intVal).val), op)
+
+ case ratVal:
+ return cmpZero(x.val.Cmp(y.(ratVal).val), op)
+
+ case floatVal:
+ return cmpZero(x.val.Cmp(y.(floatVal).val), op)
+
+ case complexVal:
+ y := y.(complexVal)
+ re := Compare(x.re, token.EQL, y.re)
+ im := Compare(x.im, token.EQL, y.im)
+ switch op {
+ case token.EQL:
+ return re && im
+ case token.NEQ:
+ return !re || !im
+ }
+
+ case *stringVal:
+ xs := x.string()
+ ys := y.(*stringVal).string()
+ switch op {
+ case token.EQL:
+ return xs == ys
+ case token.NEQ:
+ return xs != ys
+ case token.LSS:
+ return xs < ys
+ case token.LEQ:
+ return xs <= ys
+ case token.GTR:
+ return xs > ys
+ case token.GEQ:
+ return xs >= ys
+ }
+ }
+
+ panic(fmt.Sprintf("invalid comparison %v %s %v", x_, op, y_))
+}
diff --git a/src/go/constant/value_test.go b/src/go/constant/value_test.go
new file mode 100644
index 0000000..2866774
--- /dev/null
+++ b/src/go/constant/value_test.go
@@ -0,0 +1,708 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package constant
+
+import (
+ "fmt"
+ "go/token"
+ "math"
+ "math/big"
+ "strings"
+ "testing"
+)
+
+var intTests = []string{
+ // 0-octals
+ `0_123 = 0123`,
+ `0123_456 = 0123456`,
+
+ // decimals
+ `1_234 = 1234`,
+ `1_234_567 = 1234567`,
+
+ // hexadecimals
+ `0X_0 = 0`,
+ `0X_1234 = 0x1234`,
+ `0X_CAFE_f00d = 0xcafef00d`,
+
+ // octals
+ `0o0 = 0`,
+ `0o1234 = 01234`,
+ `0o01234567 = 01234567`,
+
+ `0O0 = 0`,
+ `0O1234 = 01234`,
+ `0O01234567 = 01234567`,
+
+ `0o_0 = 0`,
+ `0o_1234 = 01234`,
+ `0o0123_4567 = 01234567`,
+
+ `0O_0 = 0`,
+ `0O_1234 = 01234`,
+ `0O0123_4567 = 01234567`,
+
+ // binaries
+ `0b0 = 0`,
+ `0b1011 = 0xb`,
+ `0b00101101 = 0x2d`,
+
+ `0B0 = 0`,
+ `0B1011 = 0xb`,
+ `0B00101101 = 0x2d`,
+
+ `0b_0 = 0`,
+ `0b10_11 = 0xb`,
+ `0b_0010_1101 = 0x2d`,
+}
+
+// The RHS operand may be a floating-point quotient n/d of two integer values n and d.
+var floatTests = []string{
+ // decimal floats
+ `1_2_3. = 123.`,
+ `0_123. = 123.`,
+
+ `0_0e0 = 0.`,
+ `1_2_3e0 = 123.`,
+ `0_123e0 = 123.`,
+
+ `0e-0_0 = 0.`,
+ `1_2_3E+0 = 123.`,
+ `0123E1_2_3 = 123e123`,
+
+ `0.e+1 = 0.`,
+ `123.E-1_0 = 123e-10`,
+ `01_23.e123 = 123e123`,
+
+ `.0e-1 = .0`,
+ `.123E+10 = .123e10`,
+ `.0123E123 = .0123e123`,
+
+ `1_2_3.123 = 123.123`,
+ `0123.01_23 = 123.0123`,
+
+ `1e-1000000000 = 0`,
+ `1e+1000000000 = ?`,
+ `6e5518446744 = ?`,
+ `-6e5518446744 = ?`,
+
+ // hexadecimal floats
+ `0x0.p+0 = 0.`,
+ `0Xdeadcafe.p-10 = 0xdeadcafe/1024`,
+ `0x1234.P84 = 0x1234000000000000000000000`,
+
+ `0x.1p-0 = 1/16`,
+ `0X.deadcafep4 = 0xdeadcafe/0x10000000`,
+ `0x.1234P+12 = 0x1234/0x10`,
+
+ `0x0p0 = 0.`,
+ `0Xdeadcafep+1 = 0x1bd5b95fc`,
+ `0x1234P-10 = 0x1234/1024`,
+
+ `0x0.0p0 = 0.`,
+ `0Xdead.cafep+1 = 0x1bd5b95fc/0x10000`,
+ `0x12.34P-10 = 0x1234/0x40000`,
+
+ `0Xdead_cafep+1 = 0xdeadcafep+1`,
+ `0x_1234P-10 = 0x1234p-10`,
+
+ `0X_dead_cafe.p-10 = 0xdeadcafe.p-10`,
+ `0x12_34.P1_2_3 = 0x1234.p123`,
+}
+
+var imagTests = []string{
+ `1_234i = 1234i`,
+ `1_234_567i = 1234567i`,
+
+ `0.i = 0i`,
+ `123.i = 123i`,
+ `0123.i = 123i`,
+
+ `0.e+1i = 0i`,
+ `123.E-1_0i = 123e-10i`,
+ `01_23.e123i = 123e123i`,
+
+ `1e-1000000000i = 0i`,
+ `1e+1000000000i = ?`,
+ `6e5518446744i = ?`,
+ `-6e5518446744i = ?`,
+}
+
+func testNumbers(t *testing.T, kind token.Token, tests []string) {
+ for _, test := range tests {
+ a := strings.Split(test, " = ")
+ if len(a) != 2 {
+ t.Errorf("invalid test case: %s", test)
+ continue
+ }
+
+ x := MakeFromLiteral(a[0], kind, 0)
+ var y Value
+ if a[1] == "?" {
+ y = MakeUnknown()
+ } else {
+ if i := strings.Index(a[1], "/"); i >= 0 && kind == token.FLOAT {
+ n := MakeFromLiteral(a[1][:i], token.INT, 0)
+ d := MakeFromLiteral(a[1][i+1:], token.INT, 0)
+ y = BinaryOp(n, token.QUO, d)
+ } else {
+ y = MakeFromLiteral(a[1], kind, 0)
+ }
+ if y.Kind() == Unknown {
+ panic(fmt.Sprintf("invalid test case: %s %d", test, y.Kind()))
+ }
+ }
+
+ xk := x.Kind()
+ yk := y.Kind()
+ if xk != yk {
+ t.Errorf("%s: got kind %d != %d", test, xk, yk)
+ continue
+ }
+
+ if yk == Unknown {
+ continue
+ }
+
+ if !Compare(x, token.EQL, y) {
+ t.Errorf("%s: %s != %s", test, x, y)
+ }
+ }
+}
+
+// TestNumbers verifies that differently written literals
+// representing the same number do have the same value.
+func TestNumbers(t *testing.T) {
+ testNumbers(t, token.INT, intTests)
+ testNumbers(t, token.FLOAT, floatTests)
+ testNumbers(t, token.IMAG, imagTests)
+}
+
+var opTests = []string{
+ // unary operations
+ `+ 0 = 0`,
+ `+ ? = ?`,
+ `- 1 = -1`,
+ `- ? = ?`,
+ `^ 0 = -1`,
+ `^ ? = ?`,
+
+ `! true = false`,
+ `! false = true`,
+ `! ? = ?`,
+
+ // etc.
+
+ // binary operations
+ `"" + "" = ""`,
+ `"foo" + "" = "foo"`,
+ `"" + "bar" = "bar"`,
+ `"foo" + "bar" = "foobar"`,
+
+ `0 + 0 = 0`,
+ `0 + 0.1 = 0.1`,
+ `0 + 0.1i = 0.1i`,
+ `0.1 + 0.9 = 1`,
+ `1e100 + 1e100 = 2e100`,
+ `? + 0 = ?`,
+ `0 + ? = ?`,
+
+ `0 - 0 = 0`,
+ `0 - 0.1 = -0.1`,
+ `0 - 0.1i = -0.1i`,
+ `1e100 - 1e100 = 0`,
+ `? - 0 = ?`,
+ `0 - ? = ?`,
+
+ `0 * 0 = 0`,
+ `1 * 0.1 = 0.1`,
+ `1 * 0.1i = 0.1i`,
+ `1i * 1i = -1`,
+ `? * 0 = ?`,
+ `0 * ? = ?`,
+ `0 * 1e+1000000000 = ?`,
+
+ `0 / 0 = "division_by_zero"`,
+ `10 / 2 = 5`,
+ `5 / 3 = 5/3`,
+ `5i / 3i = 5/3`,
+ `? / 0 = ?`,
+ `0 / ? = ?`,
+ `0 * 1e+1000000000i = ?`,
+
+ `0 % 0 = "runtime_error:_integer_divide_by_zero"`, // TODO(gri) should be the same as for /
+ `10 % 3 = 1`,
+ `? % 0 = ?`,
+ `0 % ? = ?`,
+
+ `0 & 0 = 0`,
+ `12345 & 0 = 0`,
+ `0xff & 0xf = 0xf`,
+ `? & 0 = ?`,
+ `0 & ? = ?`,
+
+ `0 | 0 = 0`,
+ `12345 | 0 = 12345`,
+ `0xb | 0xa0 = 0xab`,
+ `? | 0 = ?`,
+ `0 | ? = ?`,
+
+ `0 ^ 0 = 0`,
+ `1 ^ -1 = -2`,
+ `? ^ 0 = ?`,
+ `0 ^ ? = ?`,
+
+ `0 &^ 0 = 0`,
+ `0xf &^ 1 = 0xe`,
+ `1 &^ 0xf = 0`,
+ // etc.
+
+ // shifts
+ `0 << 0 = 0`,
+ `1 << 10 = 1024`,
+ `0 >> 0 = 0`,
+ `1024 >> 10 == 1`,
+ `? << 0 == ?`,
+ `? >> 10 == ?`,
+ // etc.
+
+ // comparisons
+ `false == false = true`,
+ `false == true = false`,
+ `true == false = false`,
+ `true == true = true`,
+
+ `false != false = false`,
+ `false != true = true`,
+ `true != false = true`,
+ `true != true = false`,
+
+ `"foo" == "bar" = false`,
+ `"foo" != "bar" = true`,
+ `"foo" < "bar" = false`,
+ `"foo" <= "bar" = false`,
+ `"foo" > "bar" = true`,
+ `"foo" >= "bar" = true`,
+
+ `0 == 0 = true`,
+ `0 != 0 = false`,
+ `0 < 10 = true`,
+ `10 <= 10 = true`,
+ `0 > 10 = false`,
+ `10 >= 10 = true`,
+
+ `1/123456789 == 1/123456789 == true`,
+ `1/123456789 != 1/123456789 == false`,
+ `1/123456789 < 1/123456788 == true`,
+ `1/123456788 <= 1/123456789 == false`,
+ `0.11 > 0.11 = false`,
+ `0.11 >= 0.11 = true`,
+
+ `? == 0 = false`,
+ `? != 0 = false`,
+ `? < 10 = false`,
+ `? <= 10 = false`,
+ `? > 10 = false`,
+ `? >= 10 = false`,
+
+ `0 == ? = false`,
+ `0 != ? = false`,
+ `0 < ? = false`,
+ `10 <= ? = false`,
+ `0 > ? = false`,
+ `10 >= ? = false`,
+
+ // etc.
+}
+
+func TestOps(t *testing.T) {
+ for _, test := range opTests {
+ a := strings.Split(test, " ")
+ i := 0 // operator index
+
+ var x, x0 Value
+ switch len(a) {
+ case 4:
+ // unary operation
+ case 5:
+ // binary operation
+ x, x0 = val(a[0]), val(a[0])
+ i = 1
+ default:
+ t.Errorf("invalid test case: %s", test)
+ continue
+ }
+
+ op, ok := optab[a[i]]
+ if !ok {
+ panic("missing optab entry for " + a[i])
+ }
+
+ y, y0 := val(a[i+1]), val(a[i+1])
+
+ got := doOp(x, op, y)
+ want := val(a[i+3])
+ if !eql(got, want) {
+ t.Errorf("%s: got %s; want %s", test, got, want)
+ continue
+ }
+
+ if x0 != nil && !eql(x, x0) {
+ t.Errorf("%s: x changed to %s", test, x)
+ continue
+ }
+
+ if !eql(y, y0) {
+ t.Errorf("%s: y changed to %s", test, y)
+ continue
+ }
+ }
+}
+
+func eql(x, y Value) bool {
+ _, ux := x.(unknownVal)
+ _, uy := y.(unknownVal)
+ if ux || uy {
+ return ux == uy
+ }
+ return Compare(x, token.EQL, y)
+}
+
+// ----------------------------------------------------------------------------
+// String tests
+
+var xxx = strings.Repeat("x", 68)
+var issue14262 = `"بموجب الشروط التالية نسب المصنف — يجب عليك أن تنسب العمل بالطريقة التي تحددها المؤلف أو المرخص (ولكن ليس بأي حال من الأحوال أن توحي وتقترح بتحول أو استخدامك للعمل). المشاركة على قدم المساواة — إذا كنت يعدل ، والتغيير ، أو الاستفادة من هذا العمل ، قد ينتج عن توزيع العمل إلا في ظل تشابه او تطابق فى واحد لهذا الترخيص."`
+
+var stringTests = []struct {
+ input, short, exact string
+}{
+ // Unknown
+ {"", "unknown", "unknown"},
+ {"0x", "unknown", "unknown"},
+ {"'", "unknown", "unknown"},
+ {"1f0", "unknown", "unknown"},
+ {"unknown", "unknown", "unknown"},
+
+ // Bool
+ {"true", "true", "true"},
+ {"false", "false", "false"},
+
+ // String
+ {`""`, `""`, `""`},
+ {`"foo"`, `"foo"`, `"foo"`},
+ {`"` + xxx + `xx"`, `"` + xxx + `xx"`, `"` + xxx + `xx"`},
+ {`"` + xxx + `xxx"`, `"` + xxx + `...`, `"` + xxx + `xxx"`},
+ {`"` + xxx + xxx + `xxx"`, `"` + xxx + `...`, `"` + xxx + xxx + `xxx"`},
+ {issue14262, `"بموجب الشروط التالية نسب المصنف — يجب عليك أن تنسب العمل بالطريقة ال...`, issue14262},
+
+ // Int
+ {"0", "0", "0"},
+ {"-1", "-1", "-1"},
+ {"12345", "12345", "12345"},
+ {"-12345678901234567890", "-12345678901234567890", "-12345678901234567890"},
+ {"12345678901234567890", "12345678901234567890", "12345678901234567890"},
+
+ // Float
+ {"0.", "0", "0"},
+ {"-0.0", "0", "0"},
+ {"10.0", "10", "10"},
+ {"2.1", "2.1", "21/10"},
+ {"-2.1", "-2.1", "-21/10"},
+ {"1e9999", "1e+9999", "0x.f8d4a9da224650a8cb2959e10d985ad92adbd44c62917e608b1f24c0e1b76b6f61edffeb15c135a4b601637315f7662f325f82325422b244286a07663c9415d2p+33216"},
+ {"1e-9999", "1e-9999", "0x.83b01ba6d8c0425eec1b21e96f7742d63c2653ed0a024cf8a2f9686df578d7b07d7a83d84df6a2ec70a921d1f6cd5574893a7eda4d28ee719e13a5dce2700759p-33215"},
+ {"2.71828182845904523536028747135266249775724709369995957496696763", "2.71828", "271828182845904523536028747135266249775724709369995957496696763/100000000000000000000000000000000000000000000000000000000000000"},
+ {"0e9999999999", "0", "0"}, // issue #16176
+ {"-6e-1886451601", "0", "0"}, // issue #20228
+
+ // Complex
+ {"0i", "(0 + 0i)", "(0 + 0i)"},
+ {"-0i", "(0 + 0i)", "(0 + 0i)"},
+ {"10i", "(0 + 10i)", "(0 + 10i)"},
+ {"-10i", "(0 + -10i)", "(0 + -10i)"},
+ {"1e9999i", "(0 + 1e+9999i)", "(0 + 0x.f8d4a9da224650a8cb2959e10d985ad92adbd44c62917e608b1f24c0e1b76b6f61edffeb15c135a4b601637315f7662f325f82325422b244286a07663c9415d2p+33216i)"},
+}
+
+func TestString(t *testing.T) {
+ for _, test := range stringTests {
+ x := val(test.input)
+ if got := x.String(); got != test.short {
+ t.Errorf("%s: got %q; want %q as short string", test.input, got, test.short)
+ }
+ if got := x.ExactString(); got != test.exact {
+ t.Errorf("%s: got %q; want %q as exact string", test.input, got, test.exact)
+ }
+ }
+}
+
+// ----------------------------------------------------------------------------
+// Support functions
+
+func val(lit string) Value {
+ if len(lit) == 0 {
+ return MakeUnknown()
+ }
+
+ switch lit {
+ case "?":
+ return MakeUnknown()
+ case "true":
+ return MakeBool(true)
+ case "false":
+ return MakeBool(false)
+ }
+
+ if i := strings.IndexByte(lit, '/'); i >= 0 {
+ // assume fraction
+ a := MakeFromLiteral(lit[:i], token.INT, 0)
+ b := MakeFromLiteral(lit[i+1:], token.INT, 0)
+ return BinaryOp(a, token.QUO, b)
+ }
+
+ tok := token.INT
+ switch first, last := lit[0], lit[len(lit)-1]; {
+ case first == '"' || first == '`':
+ tok = token.STRING
+ lit = strings.ReplaceAll(lit, "_", " ")
+ case first == '\'':
+ tok = token.CHAR
+ case last == 'i':
+ tok = token.IMAG
+ default:
+ if !strings.HasPrefix(lit, "0x") && strings.ContainsAny(lit, "./Ee") {
+ tok = token.FLOAT
+ }
+ }
+
+ return MakeFromLiteral(lit, tok, 0)
+}
+
+var optab = map[string]token.Token{
+ "!": token.NOT,
+
+ "+": token.ADD,
+ "-": token.SUB,
+ "*": token.MUL,
+ "/": token.QUO,
+ "%": token.REM,
+
+ "<<": token.SHL,
+ ">>": token.SHR,
+
+ "&": token.AND,
+ "|": token.OR,
+ "^": token.XOR,
+ "&^": token.AND_NOT,
+
+ "==": token.EQL,
+ "!=": token.NEQ,
+ "<": token.LSS,
+ "<=": token.LEQ,
+ ">": token.GTR,
+ ">=": token.GEQ,
+}
+
+func panicHandler(v *Value) {
+ switch p := recover().(type) {
+ case nil:
+ // nothing to do
+ case string:
+ *v = MakeString(p)
+ case error:
+ *v = MakeString(p.Error())
+ default:
+ panic(p)
+ }
+}
+
+func doOp(x Value, op token.Token, y Value) (z Value) {
+ defer panicHandler(&z)
+
+ if x == nil {
+ return UnaryOp(op, y, 0)
+ }
+
+ switch op {
+ case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
+ return MakeBool(Compare(x, op, y))
+ case token.SHL, token.SHR:
+ s, _ := Int64Val(y)
+ return Shift(x, op, uint(s))
+ default:
+ return BinaryOp(x, op, y)
+ }
+}
+
+// ----------------------------------------------------------------------------
+// Other tests
+
+var fracTests = []string{
+ "0",
+ "1",
+ "-1",
+ "1.2",
+ "-0.991",
+ "2.718281828",
+ "3.14159265358979323e-10",
+ "1e100",
+ "1e1000",
+}
+
+func TestFractions(t *testing.T) {
+ for _, test := range fracTests {
+ x := val(test)
+ // We don't check the actual numerator and denominator because they
+ // are unlikely to be 100% correct due to floatVal rounding errors.
+ // Instead, we compute the fraction again and compare the rounded
+ // result.
+ q := BinaryOp(Num(x), token.QUO, Denom(x))
+ got := q.String()
+ want := x.String()
+ if got != want {
+ t.Errorf("%s: got quotient %s, want %s", x, got, want)
+ }
+ }
+}
+
+var bytesTests = []string{
+ "0",
+ "1",
+ "123456789",
+ "123456789012345678901234567890123456789012345678901234567890",
+}
+
+func TestBytes(t *testing.T) {
+ for _, test := range bytesTests {
+ x := val(test)
+ bytes := Bytes(x)
+
+ // special case 0
+ if Sign(x) == 0 && len(bytes) != 0 {
+ t.Errorf("%s: got %v; want empty byte slice", test, bytes)
+ }
+
+ if n := len(bytes); n > 0 && bytes[n-1] == 0 {
+ t.Errorf("%s: got %v; want no leading 0 byte", test, bytes)
+ }
+
+ if got := MakeFromBytes(bytes); !eql(got, x) {
+ t.Errorf("%s: got %s; want %s (bytes = %v)", test, got, x, bytes)
+ }
+ }
+}
+
+func TestUnknown(t *testing.T) {
+ u := MakeUnknown()
+ var values = []Value{
+ u,
+ MakeBool(false), // token.ADD ok below, operation is never considered
+ MakeString(""),
+ MakeInt64(1),
+ MakeFromLiteral("''", token.CHAR, 0),
+ MakeFromLiteral("-1234567890123456789012345678901234567890", token.INT, 0),
+ MakeFloat64(1.2),
+ MakeImag(MakeFloat64(1.2)),
+ }
+ for _, val := range values {
+ x, y := val, u
+ for i := range [2]int{} {
+ if i == 1 {
+ x, y = y, x
+ }
+ if got := BinaryOp(x, token.ADD, y); got.Kind() != Unknown {
+ t.Errorf("%s + %s: got %s; want %s", x, y, got, u)
+ }
+ if got := Compare(x, token.EQL, y); got {
+ t.Errorf("%s == %s: got true; want false", x, y)
+ }
+ }
+ }
+}
+
+func TestMakeFloat64(t *testing.T) {
+ var zero float64
+ for _, arg := range []float64{
+ -math.MaxFloat32,
+ -10,
+ -0.5,
+ -zero,
+ zero,
+ 1,
+ 10,
+ 123456789.87654321e-23,
+ 1e10,
+ math.MaxFloat64,
+ } {
+ val := MakeFloat64(arg)
+ if val.Kind() != Float {
+ t.Errorf("%v: got kind = %d; want %d", arg, val.Kind(), Float)
+ }
+
+ // -0.0 is mapped to 0.0
+ got, exact := Float64Val(val)
+ if !exact || math.Float64bits(got) != math.Float64bits(arg+0) {
+ t.Errorf("%v: got %v (exact = %v)", arg, got, exact)
+ }
+ }
+
+ // infinity
+ for sign := range []int{-1, 1} {
+ arg := math.Inf(sign)
+ val := MakeFloat64(arg)
+ if val.Kind() != Unknown {
+ t.Errorf("%v: got kind = %d; want %d", arg, val.Kind(), Unknown)
+ }
+ }
+}
+
+type makeTestCase struct {
+ kind Kind
+ arg, want interface{}
+}
+
+func dup(k Kind, x interface{}) makeTestCase { return makeTestCase{k, x, x} }
+
+func TestMake(t *testing.T) {
+ for _, test := range []makeTestCase{
+ {Bool, false, false},
+ {String, "hello", "hello"},
+
+ {Int, int64(1), int64(1)},
+ {Int, big.NewInt(10), int64(10)},
+ {Int, new(big.Int).Lsh(big.NewInt(1), 62), int64(1 << 62)},
+ dup(Int, new(big.Int).Lsh(big.NewInt(1), 63)),
+
+ {Float, big.NewFloat(0), floatVal0.val},
+ dup(Float, big.NewFloat(2.0)),
+ dup(Float, big.NewRat(1, 3)),
+ } {
+ val := Make(test.arg)
+ got := Val(val)
+ if val.Kind() != test.kind || got != test.want {
+ t.Errorf("got %v (%T, kind = %d); want %v (%T, kind = %d)",
+ got, got, val.Kind(), test.want, test.want, test.kind)
+ }
+ }
+}
+
+func BenchmarkStringAdd(b *testing.B) {
+ for size := 1; size <= 65536; size *= 4 {
+ b.Run(fmt.Sprint(size), func(b *testing.B) {
+ b.ReportAllocs()
+ n := int64(0)
+ for i := 0; i < b.N; i++ {
+ x := MakeString(strings.Repeat("x", 100))
+ y := x
+ for j := 0; j < size-1; j++ {
+ y = BinaryOp(y, token.ADD, x)
+ }
+ n += int64(len(StringVal(y)))
+ }
+ if n != int64(b.N)*int64(size)*100 {
+ b.Fatalf("bad string %d != %d", n, int64(b.N)*int64(size)*100)
+ }
+ })
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 19:57:54 +0000