Add the sprig functions in the template engine

vendor/github.com/aokoli/goutils/stringutils.go

@@ -0,0 +1,224 @@
+/*
+Copyright 2014 Alexander Okoli
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package goutils
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+	"unicode"
+)
+
+// Typically returned by functions where a searched item cannot be found
+const INDEX_NOT_FOUND = -1
+
+/*
+Abbreviate abbreviates a string using ellipses. This will turn  the string "Now is the time for all good men" into "Now is the time for..."
+
+Specifically, the algorithm is as follows:
+
+    - If str is less than maxWidth characters long, return it.
+    - Else abbreviate it to (str[0:maxWidth - 3] + "...").
+    - If maxWidth is less than 4, return an illegal argument error.
+    - In no case will it return a string of length greater than maxWidth.
+
+Parameters:
+    str -  the string to check
+    maxWidth - maximum length of result string, must be at least 4
+
+Returns:
+    string - abbreviated string
+    error - if the width is too small
+*/
+func Abbreviate(str string, maxWidth int) (string, error) {
+	return AbbreviateFull(str, 0, maxWidth)
+}
+
+/*
+AbbreviateFull abbreviates a string using ellipses. This will turn the string "Now is the time for all good men" into "...is the time for..."
+This function works like Abbreviate(string, int), but allows you to specify a "left edge" offset. Note that this left edge is not
+necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear
+somewhere in the result.
+In no case will it return a string of length greater than maxWidth.
+
+Parameters:
+    str - the string to check
+    offset - left edge of source string
+    maxWidth - maximum length of result string, must be at least 4
+
+Returns:
+    string - abbreviated string
+    error - if the width is too small
+*/
+func AbbreviateFull(str string, offset int, maxWidth int) (string, error) {
+	if str == "" {
+		return "", nil
+	}
+	if maxWidth < 4 {
+		err := fmt.Errorf("stringutils illegal argument: Minimum abbreviation width is 4")
+		return "", err
+	}
+	if len(str) <= maxWidth {
+		return str, nil
+	}
+	if offset > len(str) {
+		offset = len(str)
+	}
+	if len(str)-offset < (maxWidth - 3) { // 15 - 5 < 10 - 3 =  10 < 7
+		offset = len(str) - (maxWidth - 3)
+	}
+	abrevMarker := "..."
+	if offset <= 4 {
+		return str[0:maxWidth-3] + abrevMarker, nil // str.substring(0, maxWidth - 3) + abrevMarker;
+	}
+	if maxWidth < 7 {
+		err := fmt.Errorf("stringutils illegal argument: Minimum abbreviation width with offset is 7")
+		return "", err
+	}
+	if (offset + maxWidth - 3) < len(str) { // 5 + (10-3) < 15 = 12 < 15
+		abrevStr, _ := Abbreviate(str[offset:len(str)], (maxWidth - 3))
+		return abrevMarker + abrevStr, nil // abrevMarker + abbreviate(str.substring(offset), maxWidth - 3);
+	}
+	return abrevMarker + str[(len(str)-(maxWidth-3)):len(str)], nil // abrevMarker + str.substring(str.length() - (maxWidth - 3));
+}
+
+/*
+DeleteWhiteSpace deletes all whitespaces from a string as defined by unicode.IsSpace(rune).
+It returns the string without whitespaces.
+
+Parameter:
+    str - the string to delete whitespace from, may be nil
+
+Returns:
+    the string without whitespaces
+*/
+func DeleteWhiteSpace(str string) string {
+	if str == "" {
+		return str
+	}
+	sz := len(str)
+	var chs bytes.Buffer
+	count := 0
+	for i := 0; i < sz; i++ {
+		ch := rune(str[i])
+		if !unicode.IsSpace(ch) {
+			chs.WriteRune(ch)
+			count++
+		}
+	}
+	if count == sz {
+		return str
+	}
+	return chs.String()
+}
+
+/*
+IndexOfDifference compares two strings, and returns the index at which the strings begin to differ.
+
+Parameters:
+    str1 - the first string
+    str2 - the second string
+
+Returns:
+    the index where str1 and str2 begin to differ; -1 if they are equal
+*/
+func IndexOfDifference(str1 string, str2 string) int {
+	if str1 == str2 {
+		return INDEX_NOT_FOUND
+	}
+	if IsEmpty(str1) || IsEmpty(str2) {
+		return 0
+	}
+	var i int
+	for i = 0; i < len(str1) && i < len(str2); i++ {
+		if rune(str1[i]) != rune(str2[i]) {
+			break
+		}
+	}
+	if i < len(str2) || i < len(str1) {
+		return i
+	}
+	return INDEX_NOT_FOUND
+}
+
+/*
+IsBlank checks if a string is whitespace or empty (""). Observe the following behavior:
+
+    goutils.IsBlank("")        = true
+    goutils.IsBlank(" ")       = true
+    goutils.IsBlank("bob")     = false
+    goutils.IsBlank("  bob  ") = false
+
+Parameter:
+    str - the string to check
+
+Returns:
+    true - if the string is whitespace or empty ("")
+*/
+func IsBlank(str string) bool {
+	strLen := len(str)
+	if str == "" || strLen == 0 {
+		return true
+	}
+	for i := 0; i < strLen; i++ {
+		if unicode.IsSpace(rune(str[i])) == false {
+			return false
+		}
+	}
+	return true
+}
+
+/*
+IndexOf returns the index of the first instance of sub in str, with the search beginning from the
+index start point specified. -1 is returned if sub is not present in str.
+
+An empty string ("") will return -1 (INDEX_NOT_FOUND). A negative start position is treated as zero.
+A start position greater than the string length returns -1.
+
+Parameters:
+    str - the string to check
+    sub - the substring to find
+    start - the start position; negative treated as zero
+
+Returns:
+    the first index where the sub string was found  (always >= start)
+*/
+func IndexOf(str string, sub string, start int) int {
+
+	if start < 0 {
+		start = 0
+	}
+
+	if len(str) < start {
+		return INDEX_NOT_FOUND
+	}
+
+	if IsEmpty(str) || IsEmpty(sub) {
+		return INDEX_NOT_FOUND
+	}
+
+	partialIndex := strings.Index(str[start:len(str)], sub)
+	if partialIndex == -1 {
+		return INDEX_NOT_FOUND
+	}
+	return partialIndex + start
+}
+
+// IsEmpty checks if a string is empty (""). Returns true if empty, and false otherwise.
+func IsEmpty(str string) bool {
+	return len(str) == 0
+}