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author | Marvin Stenger <marvin.stenger94@gmail.com> | 2017-09-21 18:48:12 +0200 |
---|---|---|
committer | Robert Griesemer <gri@golang.org> | 2017-10-04 17:16:52 +0000 |
commit | aa00c607e1c2e873ef0314eb3d029a4ab3bd7252 (patch) | |
tree | e9b0a6bcee747e47857e334e5717b0de86abb886 /src/math | |
parent | 3a35e0253c8344ae4efb975e4bdc0cc53b841e0a (diff) | |
download | go-git-aa00c607e1c2e873ef0314eb3d029a4ab3bd7252.tar.gz |
math/big: remove []byte/string conversions
This removes some of the []byte/string conversions currently
existing in the (un)marshaling methods of Int and Rat.
For Int we introduce a new function (*Int).setFromScanner() essentially
implementing the SetString method being given an io.ByteScanner instead
of a string. So we can handle the string case in (*Int).SetString with
a *strings.Reader and the []byte case in (*Int).UnmarshalText() with a
*bytes.Reader now avoiding the []byte/string conversion here.
For Rat we introduce a new function (*Rat).marshal() essentially
implementing the String method outputting []byte instead of string.
Using this new function and the same formatting rules as in
(*Rat).RatString we can implement (*Rat).MarshalText() without
the []byte/string conversion it used to have.
Change-Id: Ic5ef246c1582c428a40f214b95a16671ef0a06d9
Reviewed-on: https://go-review.googlesource.com/65950
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src/math')
-rw-r--r-- | src/math/big/int.go | 11 | ||||
-rw-r--r-- | src/math/big/intmarsh.go | 8 | ||||
-rw-r--r-- | src/math/big/ratconv.go | 7 | ||||
-rw-r--r-- | src/math/big/ratmarsh.go | 6 |
4 files changed, 23 insertions, 9 deletions
diff --git a/src/math/big/int.go b/src/math/big/int.go index 63a750cb96..000eab50b7 100644 --- a/src/math/big/int.go +++ b/src/math/big/int.go @@ -390,15 +390,20 @@ func (x *Int) IsUint64() bool { // ``0b'' or ``0B'' prefix selects base 2. Otherwise the selected base is 10. // func (z *Int) SetString(s string, base int) (*Int, bool) { - r := strings.NewReader(s) + return z.setFromScanner(strings.NewReader(s), base) +} + +// setFromScanner implements SetString given an io.BytesScanner. +// For documentation see comments of SetString. +func (z *Int) setFromScanner(r io.ByteScanner, base int) (*Int, bool) { if _, _, err := z.scan(r, base); err != nil { return nil, false } - // entire string must have been consumed + // entire content must have been consumed if _, err := r.ReadByte(); err != io.EOF { return nil, false } - return z, true // err == io.EOF => scan consumed all of s + return z, true // err == io.EOF => scan consumed all content of r } // SetBytes interprets buf as the bytes of a big-endian unsigned diff --git a/src/math/big/intmarsh.go b/src/math/big/intmarsh.go index ee1e4143ed..c1422e2710 100644 --- a/src/math/big/intmarsh.go +++ b/src/math/big/intmarsh.go @@ -6,7 +6,10 @@ package big -import "fmt" +import ( + "bytes" + "fmt" +) // Gob codec version. Permits backward-compatible changes to the encoding. const intGobVersion byte = 1 @@ -52,8 +55,7 @@ func (x *Int) MarshalText() (text []byte, err error) { // UnmarshalText implements the encoding.TextUnmarshaler interface. func (z *Int) UnmarshalText(text []byte) error { - // TODO(gri): get rid of the []byte/string conversion - if _, ok := z.SetString(string(text), 0); !ok { + if _, ok := z.setFromScanner(bytes.NewReader(text), 0); !ok { return fmt.Errorf("math/big: cannot unmarshal %q into a *big.Int", text) } return nil diff --git a/src/math/big/ratconv.go b/src/math/big/ratconv.go index 3b43b19f0e..7aed289218 100644 --- a/src/math/big/ratconv.go +++ b/src/math/big/ratconv.go @@ -202,6 +202,11 @@ func scanExponent(r io.ByteScanner, binExpOk bool) (exp int64, base int, err err // String returns a string representation of x in the form "a/b" (even if b == 1). func (x *Rat) String() string { + return string(x.marshal()) +} + +// marshal implements String returning a slice of bytes +func (x *Rat) marshal() []byte { var buf []byte buf = x.a.Append(buf, 10) buf = append(buf, '/') @@ -210,7 +215,7 @@ func (x *Rat) String() string { } else { buf = append(buf, '1') } - return string(buf) + return buf } // RatString returns a string representation of x in the form "a/b" if b != 1, diff --git a/src/math/big/ratmarsh.go b/src/math/big/ratmarsh.go index b82e8d4ae8..fbc7b6002d 100644 --- a/src/math/big/ratmarsh.go +++ b/src/math/big/ratmarsh.go @@ -59,8 +59,10 @@ func (z *Rat) GobDecode(buf []byte) error { // MarshalText implements the encoding.TextMarshaler interface. func (x *Rat) MarshalText() (text []byte, err error) { - // TODO(gri): get rid of the []byte/string conversion - return []byte(x.RatString()), nil + if x.IsInt() { + return x.a.MarshalText() + } + return x.marshal(), nil } // UnmarshalText implements the encoding.TextUnmarshaler interface. |