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// Copyright 2018 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 urlreplacers
import (
"bytes"
"io"
"unicode"
"unicode/utf8"
"github.com/gohugoio/hugo/transform"
)
type absurllexer struct {
// the source to absurlify
content []byte
// the target for the new absurlified content
w io.Writer
// path may be set to a "." relative path
path []byte
pos int // input position
start int // item start position
quotes [][]byte
}
type stateFunc func(*absurllexer) stateFunc
type prefix struct {
disabled bool
b []byte
f func(l *absurllexer)
}
func newPrefixState() []*prefix {
return []*prefix{
{b: []byte("src="), f: checkCandidateBase},
{b: []byte("href="), f: checkCandidateBase},
{b: []byte("action="), f: checkCandidateBase},
{b: []byte("srcset="), f: checkCandidateSrcset},
}
}
type absURLMatcher struct {
match []byte
quote []byte
}
func (l *absurllexer) emit() {
l.w.Write(l.content[l.start:l.pos])
l.start = l.pos
}
var (
relURLPrefix = []byte("/")
relURLPrefixLen = len(relURLPrefix)
)
func (l *absurllexer) consumeQuote() []byte {
for _, q := range l.quotes {
if bytes.HasPrefix(l.content[l.pos:], q) {
l.pos += len(q)
l.emit()
return q
}
}
return nil
}
// handle URLs in src and href.
func checkCandidateBase(l *absurllexer) {
l.consumeQuote()
if !bytes.HasPrefix(l.content[l.pos:], relURLPrefix) {
return
}
// check for schemaless URLs
posAfter := l.pos + relURLPrefixLen
if posAfter >= len(l.content) {
return
}
r, _ := utf8.DecodeRune(l.content[posAfter:])
if r == '/' {
// schemaless: skip
return
}
if l.pos > l.start {
l.emit()
}
l.pos += relURLPrefixLen
l.w.Write(l.path)
l.start = l.pos
}
func (l *absurllexer) posAfterURL(q []byte) int {
if len(q) > 0 {
// look for end quote
return bytes.Index(l.content[l.pos:], q)
}
return bytes.IndexFunc(l.content[l.pos:], func(r rune) bool {
return r == '>' || unicode.IsSpace(r)
})
}
// handle URLs in srcset.
func checkCandidateSrcset(l *absurllexer) {
q := l.consumeQuote()
if q == nil {
// srcset needs to be quoted.
return
}
// special case, not frequent (me think)
if !bytes.HasPrefix(l.content[l.pos:], relURLPrefix) {
return
}
// check for schemaless URLs
posAfter := l.pos + relURLPrefixLen
if posAfter >= len(l.content) {
return
}
r, _ := utf8.DecodeRune(l.content[posAfter:])
if r == '/' {
// schemaless: skip
return
}
posEnd := l.posAfterURL(q)
// safe guard
if posEnd < 0 || posEnd > 2000 {
return
}
if l.pos > l.start {
l.emit()
}
section := l.content[l.pos : l.pos+posEnd+1]
fields := bytes.Fields(section)
for i, f := range fields {
if f[0] == '/' {
l.w.Write(l.path)
l.w.Write(f[1:])
} else {
l.w.Write(f)
}
if i < len(fields)-1 {
l.w.Write([]byte(" "))
}
}
l.pos += len(section)
l.start = l.pos
}
// main loop
func (l *absurllexer) replace() {
contentLength := len(l.content)
prefixes := newPrefixState()
for {
if l.pos >= contentLength {
break
}
nextPos := -1
var match *prefix
for _, p := range prefixes {
if p.disabled {
continue
}
idx := bytes.Index(l.content[l.pos:], p.b)
if idx == -1 {
p.disabled = true
// Find the closest match
} else if nextPos == -1 || idx < nextPos {
nextPos = idx
match = p
}
}
if nextPos == -1 {
// Done!
l.pos = contentLength
break
} else {
l.pos += nextPos + len(match.b)
match.f(l)
}
}
// Done!
if l.pos > l.start {
l.emit()
}
}
func doReplace(path string, ct transform.FromTo, quotes [][]byte) {
lexer := &absurllexer{
content: ct.From().Bytes(),
w: ct.To(),
path: []byte(path),
quotes: quotes}
lexer.replace()
}
type absURLReplacer struct {
htmlQuotes [][]byte
xmlQuotes [][]byte
}
func newAbsURLReplacer() *absURLReplacer {
return &absURLReplacer{
htmlQuotes: [][]byte{[]byte("\""), []byte("'")},
xmlQuotes: [][]byte{[]byte("""), []byte("'")}}
}
func (au *absURLReplacer) replaceInHTML(path string, ct transform.FromTo) {
doReplace(path, ct, au.htmlQuotes)
}
func (au *absURLReplacer) replaceInXML(path string, ct transform.FromTo) {
doReplace(path, ct, au.xmlQuotes)
}
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