1 files changed, 59 insertions, 0 deletions
diff --git a/doc/progs/slices.go b/doc/progs/slices.go
new file mode 100644
index 000000000..72fb4b7c1
--- /dev/null
+++ b/doc/progs/slices.go
@@ -0,0 +1,59 @@
+// Copyright 2012 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 main
+
+import (
+	"io/ioutil"
+	"regexp"
+)
+
+func AppendByte(slice []byte, data ...byte) []byte {
+	m := len(slice)
+	n := m + len(data)
+	if n > cap(slice) { // if necessary, reallocate
+		// allocate double what's needed, for future growth.
+		newSlice := make([]byte, (n+1)*2)
+		copy(newSlice, slice)
+		slice = newSlice
+	}
+	slice = slice[0:n]
+	copy(slice[m:n], data)
+	return slice
+}
+
+// STOP OMIT
+
+// Filter returns a new slice holding only
+// the elements of s that satisfy f()
+func Filter(s []int, fn func(int) bool) []int {
+	var p []int // == nil
+	for _, i := range s {
+		if fn(i) {
+			p = append(p, i)
+		}
+	}
+	return p
+}
+
+// STOP OMIT
+
+var digitRegexp = regexp.MustCompile("[0-9]+")
+
+func FindDigits(filename string) []byte {
+	b, _ := ioutil.ReadFile(filename)
+	return digitRegexp.Find(b)
+}
+
+// STOP OMIT
+
+func CopyDigits(filename string) []byte {
+	b, _ := ioutil.ReadFile(filename)
+	b = digitRegexp.Find(b)
+	c := make([]byte, len(b))
+	copy(c, b)
+	return c
+}
+
+// STOP OMIT