84 lines
1.4 KiB
Go
84 lines
1.4 KiB
Go
package strconv
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import (
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"math"
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)
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// Int parses a byte-slice and returns the integer it represents.
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// If an invalid character is encountered, it will stop there.
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func ParseInt(b []byte) (int64, int) {
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i := 0
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neg := false
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if len(b) > 0 && (b[0] == '+' || b[0] == '-') {
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neg = b[0] == '-'
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i++
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}
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n := uint64(0)
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for i < len(b) {
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c := b[i]
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if n > math.MaxUint64/10 {
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return 0, 0
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} else if c >= '0' && c <= '9' {
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n *= 10
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n += uint64(c - '0')
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} else {
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break
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}
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i++
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}
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if !neg && n > uint64(math.MaxInt64) || n > uint64(math.MaxInt64)+1 {
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return 0, 0
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} else if neg {
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return -int64(n), i
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}
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return int64(n), i
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}
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func LenInt(i int64) int {
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if i < 0 {
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if i == -9223372036854775808 {
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return 19
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}
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i = -i
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}
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switch {
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case i < 10:
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return 1
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case i < 100:
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return 2
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case i < 1000:
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return 3
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case i < 10000:
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return 4
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case i < 100000:
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return 5
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case i < 1000000:
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return 6
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case i < 10000000:
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return 7
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case i < 100000000:
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return 8
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case i < 1000000000:
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return 9
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case i < 10000000000:
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return 10
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case i < 100000000000:
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return 11
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case i < 1000000000000:
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return 12
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case i < 10000000000000:
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return 13
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case i < 100000000000000:
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return 14
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case i < 1000000000000000:
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return 15
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case i < 10000000000000000:
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return 16
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case i < 100000000000000000:
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return 17
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case i < 1000000000000000000:
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return 18
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}
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return 19
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}
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