diff options
Diffstat (limited to 'src/math/big/ratconv.go')
| -rw-r--r-- | src/math/big/ratconv.go | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/src/math/big/ratconv.go b/src/math/big/ratconv.go index da4915e74d..778077b96e 100644 --- a/src/math/big/ratconv.go +++ b/src/math/big/ratconv.go @@ -78,9 +78,8 @@ func (z *Rat) SetString(s string) (*Rat, bool) { // exponent var exp int64 - var ebase int - exp, ebase, err = scanExponent(r) - if ebase == 2 || err != nil { + exp, _, err = scanExponent(r, false) + if err != nil { return nil, false } @@ -115,7 +114,17 @@ func (z *Rat) SetString(s string) (*Rat, bool) { return z, true } -func scanExponent(r io.ByteScanner) (exp int64, base int, err error) { +// scanExponent scans the longest possible prefix of r representing a decimal +// ('e', 'E') or binary ('p') exponent, if any. It returns the exponent, the +// exponent base (10 or 2), or a read or syntax error, if any. +// +// exponent = ( "E" | "e" | "p" ) [ sign ] digits . +// sign = "+" | "-" . +// digits = digit { digit } . +// digit = "0" ... "9" . +// +// A binary exponent is only permitted if binExpOk is set. +func scanExponent(r io.ByteScanner, binExpOk bool) (exp int64, base int, err error) { base = 10 var ch byte @@ -130,7 +139,11 @@ func scanExponent(r io.ByteScanner) (exp int64, base int, err error) { case 'e', 'E': // ok case 'p': - base = 2 + if binExpOk { + base = 2 + break // ok + } + fallthrough // binary exponent not permitted default: r.UnreadByte() return // no exponent; same as e0 |