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Diffstat (limited to 'libgo/go/big/rat.go')
-rw-r--r--libgo/go/big/rat.go107
1 files changed, 76 insertions, 31 deletions
diff --git a/libgo/go/big/rat.go b/libgo/go/big/rat.go
index e70673a..327b9bd 100644
--- a/libgo/go/big/rat.go
+++ b/libgo/go/big/rat.go
@@ -6,7 +6,12 @@
package big
-import "strings"
+import (
+ "encoding/binary"
+ "fmt"
+ "os"
+ "strings"
+)
// A Rat represents a quotient a/b of arbitrary precision. The zero value for
// a Rat, 0/0, is not a legal Rat.
@@ -15,13 +20,11 @@ type Rat struct {
b nat
}
-
// NewRat creates a new Rat with numerator a and denominator b.
func NewRat(a, b int64) *Rat {
return new(Rat).SetFrac64(a, b)
}
-
// SetFrac sets z to a/b and returns z.
func (z *Rat) SetFrac(a, b *Int) *Rat {
z.a.Set(a)
@@ -30,7 +33,6 @@ func (z *Rat) SetFrac(a, b *Int) *Rat {
return z.norm()
}
-
// SetFrac64 sets z to a/b and returns z.
func (z *Rat) SetFrac64(a, b int64) *Rat {
z.a.SetInt64(a)
@@ -42,7 +44,6 @@ func (z *Rat) SetFrac64(a, b int64) *Rat {
return z.norm()
}
-
// SetInt sets z to x (by making a copy of x) and returns z.
func (z *Rat) SetInt(x *Int) *Rat {
z.a.Set(x)
@@ -50,7 +51,6 @@ func (z *Rat) SetInt(x *Int) *Rat {
return z
}
-
// SetInt64 sets z to x and returns z.
func (z *Rat) SetInt64(x int64) *Rat {
z.a.SetInt64(x)
@@ -58,7 +58,6 @@ func (z *Rat) SetInt64(x int64) *Rat {
return z
}
-
// Sign returns:
//
// -1 if x < 0
@@ -69,13 +68,11 @@ func (x *Rat) Sign() int {
return x.a.Sign()
}
-
// IsInt returns true if the denominator of x is 1.
func (x *Rat) IsInt() bool {
return len(x.b) == 1 && x.b[0] == 1
}
-
// Num returns the numerator of z; it may be <= 0.
// The result is a reference to z's numerator; it
// may change if a new value is assigned to z.
@@ -83,15 +80,13 @@ func (z *Rat) Num() *Int {
return &z.a
}
-
-// Demom returns the denominator of z; it is always > 0.
+// Denom returns the denominator of z; it is always > 0.
// The result is a reference to z's denominator; it
// may change if a new value is assigned to z.
func (z *Rat) Denom() *Int {
return &Int{false, z.b}
}
-
func gcd(x, y nat) nat {
// Euclidean algorithm.
var a, b nat
@@ -106,7 +101,6 @@ func gcd(x, y nat) nat {
return a
}
-
func (z *Rat) norm() *Rat {
f := gcd(z.a.abs, z.b)
if len(z.a.abs) == 0 {
@@ -122,7 +116,6 @@ func (z *Rat) norm() *Rat {
return z
}
-
func mulNat(x *Int, y nat) *Int {
var z Int
z.abs = z.abs.mul(x.abs, y)
@@ -130,7 +123,6 @@ func mulNat(x *Int, y nat) *Int {
return &z
}
-
// Cmp compares x and y and returns:
//
// -1 if x < y
@@ -141,7 +133,6 @@ func (x *Rat) Cmp(y *Rat) (r int) {
return mulNat(&x.a, y.b).Cmp(mulNat(&y.a, x.b))
}
-
// Abs sets z to |x| (the absolute value of x) and returns z.
func (z *Rat) Abs(x *Rat) *Rat {
z.a.Abs(&x.a)
@@ -149,7 +140,6 @@ func (z *Rat) Abs(x *Rat) *Rat {
return z
}
-
// Add sets z to the sum x+y and returns z.
func (z *Rat) Add(x, y *Rat) *Rat {
a1 := mulNat(&x.a, y.b)
@@ -159,7 +149,6 @@ func (z *Rat) Add(x, y *Rat) *Rat {
return z.norm()
}
-
// Sub sets z to the difference x-y and returns z.
func (z *Rat) Sub(x, y *Rat) *Rat {
a1 := mulNat(&x.a, y.b)
@@ -169,7 +158,6 @@ func (z *Rat) Sub(x, y *Rat) *Rat {
return z.norm()
}
-
// Mul sets z to the product x*y and returns z.
func (z *Rat) Mul(x, y *Rat) *Rat {
z.a.Mul(&x.a, &y.a)
@@ -177,7 +165,6 @@ func (z *Rat) Mul(x, y *Rat) *Rat {
return z.norm()
}
-
// Quo sets z to the quotient x/y and returns z.
// If y == 0, a division-by-zero run-time panic occurs.
func (z *Rat) Quo(x, y *Rat) *Rat {
@@ -192,7 +179,6 @@ func (z *Rat) Quo(x, y *Rat) *Rat {
return z.norm()
}
-
// Neg sets z to -x (by making a copy of x if necessary) and returns z.
func (z *Rat) Neg(x *Rat) *Rat {
z.a.Neg(&x.a)
@@ -200,7 +186,6 @@ func (z *Rat) Neg(x *Rat) *Rat {
return z
}
-
// Set sets z to x (by making a copy of x if necessary) and returns z.
func (z *Rat) Set(x *Rat) *Rat {
z.a.Set(&x.a)
@@ -208,6 +193,25 @@ func (z *Rat) Set(x *Rat) *Rat {
return z
}
+func ratTok(ch int) bool {
+ return strings.IndexRune("+-/0123456789.eE", ch) >= 0
+}
+
+// Scan is a support routine for fmt.Scanner. It accepts the formats
+// 'e', 'E', 'f', 'F', 'g', 'G', and 'v'. All formats are equivalent.
+func (z *Rat) Scan(s fmt.ScanState, ch int) os.Error {
+ tok, err := s.Token(true, ratTok)
+ if err != nil {
+ return err
+ }
+ if strings.IndexRune("efgEFGv", ch) < 0 {
+ return os.NewError("Rat.Scan: invalid verb")
+ }
+ if _, ok := z.SetString(string(tok)); !ok {
+ return os.NewError("Rat.Scan: invalid syntax")
+ }
+ return nil
+}
// SetString sets z to the value of s and returns z and a boolean indicating
// success. s can be given as a fraction "a/b" or as a floating-point number
@@ -225,8 +229,8 @@ func (z *Rat) SetString(s string) (*Rat, bool) {
return z, false
}
s = s[sep+1:]
- var n int
- if z.b, _, n = z.b.scan(s, 10); n != len(s) {
+ var err os.Error
+ if z.b, _, err = z.b.scan(strings.NewReader(s), 10); err != nil {
return z, false
}
return z.norm(), true
@@ -267,13 +271,11 @@ func (z *Rat) SetString(s string) (*Rat, bool) {
return z, true
}
-
// String returns a string representation of z in the form "a/b" (even if b == 1).
func (z *Rat) String() string {
- return z.a.String() + "/" + z.b.string(10)
+ return z.a.String() + "/" + z.b.decimalString()
}
-
// RatString returns a string representation of z in the form "a/b" if b != 1,
// and in the form "a" if b == 1.
func (z *Rat) RatString() string {
@@ -283,12 +285,15 @@ func (z *Rat) RatString() string {
return z.String()
}
-
// FloatString returns a string representation of z in decimal form with prec
// digits of precision after the decimal point and the last digit rounded.
func (z *Rat) FloatString(prec int) string {
if z.IsInt() {
- return z.a.String()
+ s := z.a.String()
+ if prec > 0 {
+ s += "." + strings.Repeat("0", prec)
+ }
+ return s
}
q, r := nat{}.div(nat{}, z.a.abs, z.b)
@@ -311,16 +316,56 @@ func (z *Rat) FloatString(prec int) string {
}
}
- s := q.string(10)
+ s := q.decimalString()
if z.a.neg {
s = "-" + s
}
if prec > 0 {
- rs := r.string(10)
+ rs := r.decimalString()
leadingZeros := prec - len(rs)
s += "." + strings.Repeat("0", leadingZeros) + rs
}
return s
}
+
+// Gob codec version. Permits backward-compatible changes to the encoding.
+const ratGobVersion byte = 1
+
+// GobEncode implements the gob.GobEncoder interface.
+func (z *Rat) GobEncode() ([]byte, os.Error) {
+ buf := make([]byte, 1+4+(len(z.a.abs)+len(z.b))*_S) // extra bytes for version and sign bit (1), and numerator length (4)
+ i := z.b.bytes(buf)
+ j := z.a.abs.bytes(buf[0:i])
+ n := i - j
+ if int(uint32(n)) != n {
+ // this should never happen
+ return nil, os.NewError("Rat.GobEncode: numerator too large")
+ }
+ binary.BigEndian.PutUint32(buf[j-4:j], uint32(n))
+ j -= 1 + 4
+ b := ratGobVersion << 1 // make space for sign bit
+ if z.a.neg {
+ b |= 1
+ }
+ buf[j] = b
+ return buf[j:], nil
+}
+
+// GobDecode implements the gob.GobDecoder interface.
+func (z *Rat) GobDecode(buf []byte) os.Error {
+ if len(buf) == 0 {
+ return os.NewError("Rat.GobDecode: no data")
+ }
+ b := buf[0]
+ if b>>1 != ratGobVersion {
+ return os.NewError(fmt.Sprintf("Rat.GobDecode: encoding version %d not supported", b>>1))
+ }
+ const j = 1 + 4
+ i := j + binary.BigEndian.Uint32(buf[j-4:j])
+ z.a.neg = b&1 != 0
+ z.a.abs = z.a.abs.setBytes(buf[j:i])
+ z.b = z.b.setBytes(buf[i:])
+ return nil
+}
generated by cgit v1.1 at 2025-04-15 00:59:00 +0000