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// Copyright 2016 The Hugo Authors. All rights reserved.
//
// 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 strings
import (
"errors"
"html"
"html/template"
"regexp"
"strings"
"unicode"
"unicode/utf8"
"github.com/spf13/cast"
)
var (
tagRE = regexp.MustCompile(`^<(/)?([^ ]+?)(?:(\s*/)| .*?)?>`)
htmlSinglets = map[string]bool{
"br": true, "col": true, "link": true,
"base": true, "img": true, "param": true,
"area": true, "hr": true, "input": true,
}
)
type htmlTag struct {
name string
pos int
openTag bool
}
// Truncate truncates the string in s to the specified length.
func (ns *Namespace) Truncate(s any, options ...any) (template.HTML, error) {
length, err := cast.ToIntE(s)
if err != nil {
return "", err
}
var textParam any
var ellipsis string
switch len(options) {
case 0:
return "", errors.New("truncate requires a length and a string")
case 1:
textParam = options[0]
ellipsis = " …"
case 2:
textParam = options[1]
ellipsis, err = cast.ToStringE(options[0])
if err != nil {
return "", errors.New("ellipsis must be a string")
}
if _, ok := options[0].(template.HTML); !ok {
ellipsis = html.EscapeString(ellipsis)
}
default:
return "", errors.New("too many arguments passed to truncate")
}
if err != nil {
return "", errors.New("text to truncate must be a string")
}
text, err := cast.ToStringE(textParam)
if err != nil {
return "", errors.New("text must be a string")
}
_, isHTML := textParam.(template.HTML)
if utf8.RuneCountInString(text) <= length {
if isHTML {
return template.HTML(text), nil
}
return template.HTML(html.EscapeString(text)), nil
}
tags := []htmlTag{}
var lastWordIndex, lastNonSpace, currentLen, endTextPos, nextTag int
for i, r := range text {
if i < nextTag {
continue
}
if isHTML {
// Make sure we keep tagname of HTML tags
slice := text[i:]
m := tagRE.FindStringSubmatchIndex(slice)
if len(m) > 0 && m[0] == 0 {
nextTag = i + m[1]
tagname := strings.Fields(slice[m[4]:m[5]])[0]
lastWordIndex = lastNonSpace
_, singlet := htmlSinglets[tagname]
if !singlet && m[6] == -1 {
tags = append(tags, htmlTag{name: tagname, pos: i, openTag: m[2] == -1})
}
continue
}
}
currentLen++
if unicode.IsSpace(r) {
lastWordIndex = lastNonSpace
} else if unicode.In(r, unicode.Han, unicode.Hangul, unicode.Hiragana, unicode.Katakana) {
lastWordIndex = i
} else {
lastNonSpace = i + utf8.RuneLen(r)
}
if currentLen > length {
if lastWordIndex == 0 {
endTextPos = i
} else {
endTextPos = lastWordIndex
}
out := text[0:endTextPos]
if isHTML {
out += ellipsis
// Close out any open HTML tags
var currentTag *htmlTag
for i := len(tags) - 1; i >= 0; i-- {
tag := tags[i]
if tag.pos >= endTextPos || currentTag != nil {
if currentTag != nil && currentTag.name == tag.name {
currentTag = nil
}
continue
}
if tag.openTag {
out += ("</" + tag.name + ">")
} else {
currentTag = &tag
}
}
return template.HTML(out), nil
}
return template.HTML(html.EscapeString(out) + ellipsis), nil
}
}
if isHTML {
return template.HTML(text), nil
}
return template.HTML(html.EscapeString(text)), nil
}
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