Add stringmanip package

Author: thebaer

stringmanip/runes.go

@@ -0,0 +1,96 @@
+package stringmanip
+
+/*
+	The MIT License (MIT)
+
+	Copyright (c) 2016 Sergey Kamardin
+
+	Permission is hereby granted, free of charge, to any person obtaining a copy
+	of this software and associated documentation files (the "Software"), to deal
+	in the Software without restriction, including without limitation the rights
+	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+	copies of the Software, and to permit persons to whom the Software is
+	furnished to do so, subject to the following conditions:
+
+	The above copyright notice and this permission notice shall be included in all
+	copies or substantial portions of the Software.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+	SOFTWARE.
+*/
+// Source: https://github.com/gobwas/glob/blob/master/util/runes/runes.go
+
+func IndexRune(str string, r rune) int {
+	s := []rune(str)
+	for i, c := range s {
+		if c == r {
+			return i
+		}
+	}
+	return -1
+}
+
+func LastIndexRune(str string, needle rune) int {
+	s := []rune(str)
+	needles := []rune{needle}
+	ls, ln := len(s), len(needles)
+
+	switch {
+	case ln == 0:
+		if ls == 0 {
+			return 0
+		}
+		return ls
+	case ln == 1:
+		return IndexLastRune(s, needles[0])
+	case ln == ls:
+		if EqualRunes(s, needles) {
+			return 0
+		}
+		return -1
+	case ln > ls:
+		return -1
+	}
+
+head:
+	for i := ls - 1; i >= 0 && i >= ln; i-- {
+		for y := ln - 1; y >= 0; y-- {
+			if s[i-(ln-y-1)] != needles[y] {
+				continue head
+			}
+		}
+
+		return i - ln + 1
+	}
+
+	return -1
+}
+
+func IndexLastRune(s []rune, r rune) int {
+	for i := len(s) - 1; i >= 0; i-- {
+		if s[i] == r {
+			return i
+		}
+	}
+
+	return -1
+}
+
+func EqualRunes(a, b []rune) bool {
+	if len(a) == len(b) {
+		for i := 0; i < len(a); i++ {
+			if a[i] != b[i] {
+				return false
+			}
+		}
+
+		return true
+	}
+
+	return false
+}

stringmanip/strings.go

@@ -0,0 +1,17 @@
+package stringmanip
+
+// Substring provides a safe way to extract a substring from a UTF-8 string.
+// From this discussion:
+//   https://groups.google.com/d/msg/golang-nuts/cGq1Irv_5Vs/0SKoj49BsWQJ
+func Substring(s string, p, l int) string {
+	if p < 0 || l <= 0 {
+		return ""
+	}
+	c := []rune(s)
+	if p > len(c) {
+		return ""
+	} else if p+l > len(c) || p+l < p {
+		return string(c[p:])
+	}
+	return string(c[p : p+l])
+}