camelcase.go

// Package helper is a micro package with helper functions for uAdmin
package helper

/*
The MIT License (MIT)

Copyright (c) 2015 Fatih Arslan

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.
*/

import (
	"regexp"
	"strings"
	"unicode"
	"unicode/utf8"
)

// SplitCamelCase the camelcase word and returns a list of words. It also
// supports digits. Both lower camel case and upper camel case are supported.
// For more info please check: http://en.wikipedia.org/wiki/CamelCase
//
// Examples
//
//   "" =>                     [""]
//   "lowercase" =>            ["lowercase"]
//   "Class" =>                ["Class"]
//   "MyClass" =>              ["My", "Class"]
//   "MyC" =>                  ["My", "C"]
//   "HTML" =>                 ["HTML"]
//   "PDFLoader" =>            ["PDF", "Loader"]
//   "AString" =>              ["A", "String"]
//   "SimpleXMLParser" =>      ["Simple", "XML", "Parser"]
//   "vimRPCPlugin" =>         ["vim", "RPC", "Plugin"]
//   "GL11Version" =>          ["GL", "11", "Version"]
//   "99Bottles" =>            ["99", "Bottles"]
//   "May5" =>                 ["May", "5"]
//   "BFG9000" =>              ["BFG", "9000"]
//   "BöseÜberraschung" =>     ["Böse", "Überraschung"]
//   "Two  spaces" =>          ["Two", "  ", "spaces"]
//   "BadUTF8\xe2\xe2\xa1" =>  ["BadUTF8\xe2\xe2\xa1"]
//
// Splitting rules
//
//  1) If string is not valid UTF-8, return it without splitting as
//     single item array.
//  2) Assign all unicode characters into one of 4 sets: lower case
//     letters, upper case letters, numbers, and all other characters.
//  3) Iterate through characters of string, introducing splits
//     between adjacent characters that belong to different sets.
//  4) Iterate through array of split strings, and if a given string
//     is upper case:
//       if subsequent string is lower case:
//         move last character of upper case string to beginning of
//         lower case string
func SplitCamelCase(src string) (entries []string) {
	// don't split invalid utf8
	if !utf8.ValidString(src) {
		return []string{src}
	}
	entries = []string{}
	var runes [][]rune
	lastClass := 0
	class := 0
	// split into fields based on class of unicode character
	for _, r := range src {
		switch true {
		case unicode.IsLower(r):
			class = 1
		case unicode.IsUpper(r):
			class = 2
		case unicode.IsDigit(r):
			class = 3
		default:
			class = 4
		}
		if class == lastClass {
			runes[len(runes)-1] = append(runes[len(runes)-1], r)
		} else {
			runes = append(runes, []rune{r})
		}
		lastClass = class
	}
	// handle upper case -> lower case sequences, e.g.
	// "PDFL", "oader" -> "PDF", "Loader"
	for i := 0; i < len(runes)-1; i++ {
		if unicode.IsUpper(runes[i][0]) && unicode.IsLower(runes[i+1][0]) {
			runes[i+1] = append([]rune{runes[i][len(runes[i])-1]}, runes[i+1]...)
			runes[i] = runes[i][:len(runes[i])-1]
		}
	}
	// construct []string from results
	for _, s := range runes {
		if len(s) > 0 {
			entries = append(entries, string(s))
		}
	}
	return
}

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Ian Coleman
 *
 * 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.
 */
var numberSequence = regexp.MustCompile(`([a-zA-Z])(\d+)([a-zA-Z]?)`)
var numberReplacement = []byte(`$1 $2 $3`)

func addWordBoundariesToNumbers(s string) string {
	b := []byte(s)
	b = numberSequence.ReplaceAll(b, numberReplacement)
	return string(b)
}

// Converts a string to CamelCase
func toCamelInitCase(s string, initCase bool) string {
	s = addWordBoundariesToNumbers(s)
	s = strings.Trim(s, " ")
	n := ""
	capNext := initCase
	for _, v := range s {
		if v >= 'A' && v <= 'Z' {
			n += string(v)
		}
		if v >= '0' && v <= '9' {
			n += string(v)
		}
		if v >= 'a' && v <= 'z' {
			if capNext {
				n += strings.ToUpper(string(v))
			} else {
				n += string(v)
			}
		}
		if v == '_' || v == ' ' || v == '-' {
			capNext = true
		} else {
			capNext = false
		}
	}
	return n
}

// ToCamel converts a string to CamelCase
func ToCamel(s string) string {
	return toCamelInitCase(s, true)
}