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Originally published on the Go blog on 5 Jan 2011: http://blog.golang.org/2011/01/go-slices-usage-and-internals.html R=golang-dev, gri CC=golang-dev https://golang.org/cl/5516046
56 lines
979 B
Go
56 lines
979 B
Go
package main
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import (
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"io/ioutil"
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"regexp"
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)
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func AppendByte(slice []byte, data ...byte) []byte {
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m := len(slice)
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n := m + len(data)
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if n > cap(slice) { // if necessary, reallocate
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// allocate double what's needed, for future growth.
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newSlice := make([]byte, (n+1)*2)
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copy(newSlice, slice)
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slice = newSlice
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}
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slice = slice[0:n]
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copy(slice[m:n], data)
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return slice
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}
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// STOP OMIT
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// Filter returns a new slice holding only
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// the elements of s that satisfy f()
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func Filter(s []int, fn func(int) bool) []int {
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var p []int // == nil
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for _, i := range s {
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if fn(i) {
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p = append(p, i)
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}
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}
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return p
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}
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// STOP OMIT
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var digitRegexp = regexp.MustCompile("[0-9]+")
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func FindDigits(filename string) []byte {
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b, _ := ioutil.ReadFile(filename)
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return digitRegexp.Find(b)
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}
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// STOP OMIT
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func CopyDigits(filename string) []byte {
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b, _ := ioutil.ReadFile(filename)
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b = digitRegexp.Find(b)
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c := make([]byte, len(b))
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copy(c, b)
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return c
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}
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// STOP OMIT
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