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sort: make return value for 'not found' clearer in docs

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It was well-defined but easy to miss that the return value for
"not found" is len(input) not -1 as many expect.

Fixes #4205.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6820080
This commit is contained in:
Rob Pike 2012-11-02 16:17:34 -07:00
parent c46f1f40da
commit 20548b153f
1 changed files with 8 additions and 3 deletions
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11
src/pkg/sort/search.go
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@ -12,6 +12,8 @@ package sort
// f is false for some (possibly empty) prefix of the input range [0, n)
// and then true for the (possibly empty) remainder; Search returns
// the first true index. If there is no such index, Search returns n.
// (Note that the "not found" return value is n, the length of the input,
// not -1 as in, for instance, strings.Index).
// Search calls f(i) only for i in the range [0, n).
//
// A common use of Search is to find the index i for a value x in
@ -74,21 +76,24 @@ func Search(n int, f func(int) bool) int {
// Convenience wrappers for common cases.
// SearchInts searches for x in a sorted slice of ints and returns the index
// as specified by Search. The slice must be sorted in ascending order.
// as specified by Search. The return value is len(a) if x is not present.
// The slice must be sorted in ascending order.
//
func SearchInts(a []int, x int) int {
return Search(len(a), func(i int) bool { return a[i] >= x })
}
// SearchFloat64s searches for x in a sorted slice of float64s and returns the index
// as specified by Search. The slice must be sorted in ascending order.
// as specified by Search. The return value is len(a) if x is not present.
// The slice must be sorted in ascending order.
//
func SearchFloat64s(a []float64, x float64) int {
return Search(len(a), func(i int) bool { return a[i] >= x })
}
// SearchStrings searches for x in a sorted slice of strings and returns the index
// as specified by Search. The slice must be sorted in ascending order.
// as specified by Search. The return value is len(a) if x is not present.
// The slice must be sorted in ascending order.
//
func SearchStrings(a []string, x string) int {
return Search(len(a), func(i int) bool { return a[i] >= x })