code review 824051: Added strings.FieldsFunc, a generalization of strings.F...

src/pkg/strings/strings.go

 // 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.
 
 // A package of simple functions to manipulate strings.
 package strings
 
 import (
         "unicode"
         "utf8"
@@ skipping 154 matching lines @@
 // SplitAfter splits the string s after each instance of sep, returning an array of substrings of s.
 // If sep is empty, SplitAfter splits s after each UTF-8 sequence.
 // If n > 0, SplitAfter splits s into at most n substrings; the last substring will be the unsplit remainder.
 func SplitAfter(s, sep string, n int) []string {
         return genSplit(s, sep, len(sep), n)
 }
 
 // Fields splits the string s around each instance of one or more consecutive white space
 // characters, returning an array of substrings of s or an empty list if s contains only white space.
 func Fields(s string) []string {
+        return FieldsFunc(s, unicode.IsSpace)
+}
+
+// FieldsFunc splits the string s at each run of Unicode code points c satifying f(c)
+// and returns an array of slices of s. If no code points in s satisfy f(c), an empty slice
+// is returned.
+func FieldsFunc(s string, f func(int) bool) []string {
         // First count the fields.
         n := 0
         inField := false
         for _, rune := range s {
                 wasInField := inField
-                inField = !unicode.IsSpace(rune)
+                inField = !f(rune)
                 if inField && !wasInField {
                         n++
                 }
         }
 
         // Now create them.
         a := make([]string, n)
         na := 0
         fieldStart := -1 // Set to -1 when looking for start of field.
         for i, rune := range s {
-                if unicode.IsSpace(rune) {
+                if f(rune) {
                         if fieldStart >= 0 {
                                 a[na] = s[fieldStart:i]
                                 na++
                                 fieldStart = -1
                         }
                 } else if fieldStart == -1 {
                         fieldStart = i
                 }
         }
         if fieldStart != -1 { // Last field might end at EOF.
@@ skipping 195 matching lines @@
                 return s
         }
         return TrimRightFunc(s, makeCutsetFunc(cutset))
 }
 
 // TrimSpace returns a slice of the string s, with all leading
 // and trailing white space removed, as defined by Unicode.
 func TrimSpace(s string) string {
         return TrimFunc(s, unicode.IsSpace)
 }