diff options
Diffstat (limited to 'libgo/go/strconv/atoi.go')
| -rw-r--r-- | libgo/go/strconv/atoi.go | 102 |
1 files changed, 37 insertions, 65 deletions
diff --git a/libgo/go/strconv/atoi.go b/libgo/go/strconv/atoi.go index 2c6c3d5..438d496 100644 --- a/libgo/go/strconv/atoi.go +++ b/libgo/go/strconv/atoi.go @@ -20,15 +20,9 @@ type NumError struct { func (e *NumError) Error() string { return `parsing "` + e.Num + `": ` + e.Err.Error() } -func computeIntsize() uint { - siz := uint(8) - for 1<<siz != 0 { - siz *= 2 - } - return siz -} +const intSize = 32 << uint(^uint(0)>>63) -var IntSize = computeIntsize() +const IntSize = intSize // number of bits in int, uint (32 or 64) // Return the first number n such that n*base >= 1<<64. func cutoff64(base int) uint64 { @@ -38,17 +32,13 @@ func cutoff64(base int) uint64 { return (1<<64-1)/uint64(base) + 1 } -// Btoui64 interprets a string s in an arbitrary base b (2 to 36) -// and returns the corresponding value n. If b == 0, the base -// is taken from the string prefix: base 16 for "0x", base 8 for "0", -// and base 10 otherwise. -// -// The errors that Btoui64 returns have concrete type *NumError -// and include err.Num = s. If s is empty or contains invalid -// digits, err.Error = ErrSyntax; if the value corresponding -// to s cannot be represented by a uint64, err.Error = ErrRange. -func Btoui64(s string, b int) (n uint64, err error) { - var cutoff uint64 +// ParseUint is like ParseInt but for unsigned numbers. +func ParseUint(s string, b int, bitSize int) (n uint64, err error) { + var cutoff, maxVal uint64 + + if bitSize == 0 { + bitSize = int(IntSize) + } s0 := s switch { @@ -82,6 +72,7 @@ func Btoui64(s string, b int) (n uint64, err error) { n = 0 cutoff = cutoff64(b) + maxVal = 1<<uint(bitSize) - 1 for i := 0; i < len(s); i++ { var v byte @@ -113,7 +104,7 @@ func Btoui64(s string, b int) (n uint64, err error) { n *= uint64(b) n1 := n + uint64(v) - if n1 < n { + if n1 < n || n1 > maxVal { // n+v overflows n = 1<<64 - 1 err = ErrRange @@ -128,18 +119,25 @@ Error: return n, &NumError{s0, err} } -// Atoui64 interprets a string s as a decimal number and -// returns the corresponding value n. +// ParseInt interprets a string s in an arbitrary base b (2 to 36) +// and returns the corresponding value n. If b == 0, the base +// is taken from the string prefix: base 16 for "0x", base 8 for "0", +// and base 10 otherwise. // -// Atoui64 returns err.Error = ErrSyntax if s is empty or contains invalid digits. -// It returns err.Error = ErrRange if s cannot be represented by a uint64. -func Atoui64(s string) (n uint64, err error) { - return Btoui64(s, 10) -} +// The bitSize argument specifies the integer type +// that the result must fit into. Bit sizes 0, 8, 16, 32, and 64 +// correspond to int, int8, int16, int32, and int64. +// +// The errors that ParseInt returns have concrete type *NumError +// and include err.Num = s. If s is empty or contains invalid +// digits, err.Error = ErrSyntax; if the value corresponding +// to s cannot be represented by a signed integer of the +// given size, err.Error = ErrRange. +func ParseInt(s string, base int, bitSize int) (i int64, err error) { + if bitSize == 0 { + bitSize = int(IntSize) + } -// Btoi64 is like Btoui64 but allows signed numbers and -// returns its result in an int64. -func Btoi64(s string, base int) (i int64, err error) { // Empty string bad. if len(s) == 0 { return 0, &NumError{s, ErrSyntax} @@ -157,16 +155,17 @@ func Btoi64(s string, base int) (i int64, err error) { // Convert unsigned and check range. var un uint64 - un, err = Btoui64(s, base) + un, err = ParseUint(s, base, bitSize) if err != nil && err.(*NumError).Err != ErrRange { err.(*NumError).Num = s0 return 0, err } - if !neg && un >= 1<<63 { - return 1<<63 - 1, &NumError{s0, ErrRange} + cutoff := uint64(1 << uint(bitSize-1)) + if !neg && un >= cutoff { + return int64(cutoff - 1), &NumError{s0, ErrRange} } - if neg && un > 1<<63 { - return -1 << 63, &NumError{s0, ErrRange} + if neg && un > cutoff { + return -int64(cutoff), &NumError{s0, ErrRange} } n := int64(un) if neg { @@ -175,35 +174,8 @@ func Btoi64(s string, base int) (i int64, err error) { return n, nil } -// Atoi64 is like Atoui64 but allows signed numbers and -// returns its result in an int64. -func Atoi64(s string) (i int64, err error) { return Btoi64(s, 10) } - -// Atoui is like Atoui64 but returns its result as a uint. -func Atoui(s string) (i uint, err error) { - i1, e1 := Atoui64(s) - if e1 != nil && e1.(*NumError).Err != ErrRange { - return 0, e1 - } - i = uint(i1) - if uint64(i) != i1 { - return ^uint(0), &NumError{s, ErrRange} - } - return i, nil -} - -// Atoi is like Atoi64 but returns its result as an int. +// Atoi is shorthand for ParseInt(s, 10, 0). func Atoi(s string) (i int, err error) { - i1, e1 := Atoi64(s) - if e1 != nil && e1.(*NumError).Err != ErrRange { - return 0, e1 - } - i = int(i1) - if int64(i) != i1 { - if i1 < 0 { - return -1 << (IntSize - 1), &NumError{s, ErrRange} - } - return 1<<(IntSize-1) - 1, &NumError{s, ErrRange} - } - return i, nil + i64, err := ParseInt(s, 10, 0) + return int(i64), err } |