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// Copyright 2009 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 strconv
import "errors"
// ErrRange indicates that a value is out of range for the target type.
var ErrRange = errors.New("value out of range")
// ErrSyntax indicates that a value does not have the right syntax for the target type.
var ErrSyntax = errors.New("invalid syntax")
// A NumError records a failed conversion.
type NumError struct {
Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat)
Num string // the input
Err error // the reason the conversion failed (ErrRange, ErrSyntax)
}
func (e *NumError) Error() string {
return "strconv." + e.Func + ": " + "parsing " + Quote(e.Num) + ": " + e.Err.Error()
}
func syntaxError(fn, str string) *NumError {
return &NumError{fn, str, ErrSyntax}
}
func rangeError(fn, str string) *NumError {
return &NumError{fn, str, ErrRange}
}
const intSize = 32 << uint(^uint(0)>>63)
// IntSize is the size in bits of an int or uint value.
const IntSize = intSize
// Return the first number n such that n*base >= 1<<64.
func cutoff64(base int) uint64 {
if base < 2 {
return 0
}
return (1<<64-1)/uint64(base) + 1
}
// ParseUint is like ParseInt but for unsigned numbers.
func ParseUint(s string, base int, bitSize int) (n uint64, err error) {
var cutoff, maxVal uint64
if bitSize == 0 {
bitSize = int(IntSize)
}
s0 := s
switch {
case len(s) < 1:
err = ErrSyntax
goto Error
case 2 <= base && base <= 36:
// valid base; nothing to do
case base == 0:
// Look for octal, hex prefix.
switch {
case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
base = 16
s = s[2:]
if len(s) < 1 {
err = ErrSyntax
goto Error
}
case s[0] == '0':
base = 8
default:
base = 10
}
default:
err = errors.New("invalid base " + Itoa(base))
goto Error
}
n = 0
cutoff = cutoff64(base)
maxVal = 1<<uint(bitSize) - 1
for i := 0; i < len(s); i++ {
var v byte
d := s[i]
switch {
case '0' <= d && d <= '9':
v = d - '0'
case 'a' <= d && d <= 'z':
v = d - 'a' + 10
case 'A' <= d && d <= 'Z':
v = d - 'A' + 10
default:
n = 0
err = ErrSyntax
goto Error
}
if int(v) >= base {
n = 0
err = ErrSyntax
goto Error
}
if n >= cutoff {
// n*base overflows
n = 1<<64 - 1
err = ErrRange
goto Error
}
n *= uint64(base)
n1 := n + uint64(v)
if n1 < n || n1 > maxVal {
// n+v overflows
n = 1<<64 - 1
err = ErrRange
goto Error
}
n = n1
}
return n, nil
Error:
return n, &NumError{"ParseUint", s0, err}
}
// ParseInt interprets a string s in the given base (2 to 36) and
// returns the corresponding value i. If base == 0, the base is
// implied by the string's prefix: base 16 for "0x", base 8 for
// "0", and base 10 otherwise.
//
// 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.Err = ErrSyntax; if the value corresponding
// to s cannot be represented by a signed integer of the
// given size, err.Err = ErrRange.
func ParseInt(s string, base int, bitSize int) (i int64, err error) {
const fnParseInt = "ParseInt"
if bitSize == 0 {
bitSize = int(IntSize)
}
// Empty string bad.
if len(s) == 0 {
return 0, syntaxError(fnParseInt, s)
}
// Pick off leading sign.
s0 := s
neg := false
if s[0] == '+' {
s = s[1:]
} else if s[0] == '-' {
neg = true
s = s[1:]
}
// Convert unsigned and check range.
var un uint64
un, err = ParseUint(s, base, bitSize)
if err != nil && err.(*NumError).Err != ErrRange {
err.(*NumError).Func = fnParseInt
err.(*NumError).Num = s0
return 0, err
}
cutoff := uint64(1 << uint(bitSize-1))
if !neg && un >= cutoff {
return int64(cutoff - 1), rangeError(fnParseInt, s0)
}
if neg && un > cutoff {
return -int64(cutoff), rangeError(fnParseInt, s0)
}
n := int64(un)
if neg {
n = -n
}
return n, nil
}
// Atoi is shorthand for ParseInt(s, 10, 0).
func Atoi(s string) (i int, err error) {
i64, err := ParseInt(s, 10, 0)
return int(i64), err
}
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