header.go

package stringcase

import "github.com/reiver/go-whitespace"
import "strings"
import "unicode"

// ToHeaderCase converts the string to "Header-Case" and returns it.
func ToHeaderCase(s string) string {

	// Here we use a similar hack that the Golang strings.Title() func uses,
	// which uses the strings.Map() func but (and this is the hack'y part)
	// depends on the interation order of strings.Map().
	//
	// See: https://golang.org/src/strings/strings.go#L519
	//
	// Specifically, assumes it iterates from beginning to end.
	//
	prev := ' '
	result := strings.Map(
		func(r rune) rune {

			if whitespace.IsWhitespace(prev) || '_' == prev || '-' == prev {
				prev = r

				return unicode.ToTitle(r)
			} else if whitespace.IsWhitespace(r) || '_' == r {
				prev = r

				return '-'
			} else {
				prev = r

				return unicode.ToLower(r)

			}
		},
		s)

	// Return
	return result
}

// FromHeaderCase converts the "Header-Case" string to a spaced string
// "Header Case" and returns it.
func FromHeaderCase(s string) string {
	return strings.Replace(s, "-", " ", -1)
}