ref: 54e417681d7bc625a6bfc4bb0f79858cf113600a
dir: /transform/absurlreplacer.go/
package transform
import (
"bytes"
bp "github.com/spf13/hugo/bufferpool"
"net/url"
"strings"
"sync"
"unicode/utf8"
)
// position (in bytes)
type pos int
type matchState int
const (
matchStateNone matchState = iota
matchStateWhitespace
matchStatePartial
matchStateFull
)
type item struct {
typ itemType
pos pos
val []byte
}
type itemType int
const (
tText itemType = iota
// matches
tSrcdq
tHrefdq
tSrcsq
tHrefsq
// guards
tGrcdq
tGhrefdq
tGsrcsq
tGhrefsq
)
type contentlexer struct {
content []byte
pos pos // input position
start pos // item start position
width pos // width of last element
matchers []absurlMatcher
state stateFunc
prefixLookup *prefixes
// items delivered to client
items []item
}
type stateFunc func(*contentlexer) stateFunc
type prefixRunes []rune
type prefixes struct {
pr []prefixRunes
curr prefixRunes // current prefix lookup table
i int // current index
// first rune in potential match
first rune
// match-state:
// none, whitespace, partial, full
ms matchState
}
// match returns partial and full match for the prefix in play
// - it's a full match if all prefix runes has checked out in row
// - it's a partial match if it's on its way towards a full match
func (l *contentlexer) match(r rune) {
p := l.prefixLookup
if p.curr == nil {
// assumes prefixes all start off on a different rune
// works in this special case: href, src
p.i = 0
for _, pr := range p.pr {
if pr[p.i] == r {
fullMatch := len(p.pr) == 1
p.first = r
if !fullMatch {
p.curr = pr
l.prefixLookup.ms = matchStatePartial
} else {
l.prefixLookup.ms = matchStateFull
}
return
}
}
} else {
p.i++
if p.curr[p.i] == r {
fullMatch := len(p.curr) == p.i+1
if fullMatch {
p.curr = nil
l.prefixLookup.ms = matchStateFull
} else {
l.prefixLookup.ms = matchStatePartial
}
return
}
p.curr = nil
}
l.prefixLookup.ms = matchStateNone
}
func (l *contentlexer) emit(t itemType) {
l.items = append(l.items, item{t, l.start, l.content[l.start:l.pos]})
l.start = l.pos
}
var mainPrefixRunes = []prefixRunes{{'s', 'r', 'c', '='}, {'h', 'r', 'e', 'f', '='}}
var itemSlicePool = &sync.Pool{
New: func() interface{} {
return make([]item, 0, 8)
},
}
func replace(content []byte, matchers []absurlMatcher) *contentlexer {
var items []item
if x := itemSlicePool.Get(); x != nil {
items = x.([]item)[:0]
defer itemSlicePool.Put(items)
} else {
items = make([]item, 0, 8)
}
lexer := &contentlexer{content: content,
items: items,
prefixLookup: &prefixes{pr: mainPrefixRunes},
matchers: matchers}
lexer.runReplacer()
return lexer
}
func (l *contentlexer) runReplacer() {
for l.state = lexReplacements; l.state != nil; {
l.state = l.state(l)
}
}
type absurlMatcher struct {
replaceType itemType
guardType itemType
match []byte
guard []byte
replacement []byte
guarded bool
}
func (a absurlMatcher) isSourceType() bool {
return a.replaceType == tSrcdq || a.replaceType == tSrcsq
}
func lexReplacements(l *contentlexer) stateFunc {
contentLength := len(l.content)
var r rune
for {
if int(l.pos) >= contentLength {
l.width = 0
break
}
var width int = 1
r = rune(l.content[l.pos])
if r >= utf8.RuneSelf {
r, width = utf8.DecodeRune(l.content[l.pos:])
}
l.width = pos(width)
l.pos += l.width
if r == ' ' {
l.prefixLookup.ms = matchStateWhitespace
} else if l.prefixLookup.ms != matchStateNone {
l.match(r)
if l.prefixLookup.ms == matchStateFull {
checkCandidate(l)
}
}
}
// Done!
if l.pos > l.start {
l.emit(tText)
}
return nil
}
func checkCandidate(l *contentlexer) {
isSource := l.prefixLookup.first == 's'
for _, m := range l.matchers {
if m.guarded {
continue
}
if isSource && !m.isSourceType() || !isSource && m.isSourceType() {
continue
}
s := l.content[l.pos:]
if bytes.HasPrefix(s, m.guard) {
if l.pos > l.start {
l.emit(tText)
}
l.pos += pos(len(m.guard))
l.emit(m.guardType)
m.guarded = true
return
} else if bytes.HasPrefix(s, m.match) {
if l.pos > l.start {
l.emit(tText)
}
l.pos += pos(len(m.match))
l.emit(m.replaceType)
return
}
}
}
func doReplace(content []byte, matchers []absurlMatcher) []byte {
b := bp.GetBuffer()
defer bp.PutBuffer(b)
guards := make([]bool, len(matchers))
replaced := replace(content, matchers)
// first pass: check guards
for _, item := range replaced.items {
if item.typ != tText {
for i, e := range matchers {
if item.typ == e.guardType {
guards[i] = true
break
}
}
}
}
// second pass: do replacements for non-guarded tokens
for _, token := range replaced.items {
switch token.typ {
case tText:
b.Write(token.val)
default:
for i, e := range matchers {
if token.typ == e.replaceType && !guards[i] {
b.Write(e.replacement)
} else if token.typ == e.replaceType || token.typ == e.guardType {
b.Write(token.val)
}
}
}
}
return b.Bytes()
}
type absurlReplacer struct {
htmlMatchers []absurlMatcher
xmlMatchers []absurlMatcher
}
func newAbsurlReplacer(baseUrl string) *absurlReplacer {
u, _ := url.Parse(baseUrl)
base := strings.TrimRight(u.String(), "/")
// HTML
dqHtmlMatch := []byte("\"/")
sqHtmlMatch := []byte("'/")
dqGuard := []byte("\"//")
sqGuard := []byte("'//")
// XML
dqXmlMatch := []byte(""/")
sqXmlMatch := []byte("'/")
dqXmlGuard := []byte(""//")
sqXmlGuard := []byte("'//")
dqHtml := []byte("\"" + base + "/")
sqHtml := []byte("'" + base + "/")
dqXml := []byte(""" + base + "/")
sqXml := []byte("'" + base + "/")
return &absurlReplacer{htmlMatchers: []absurlMatcher{
{tSrcdq, tGrcdq, dqHtmlMatch, dqGuard, dqHtml, false},
{tSrcsq, tGsrcsq, sqHtmlMatch, sqGuard, sqHtml, false},
{tHrefdq, tGhrefdq, dqHtmlMatch, dqGuard, dqHtml, false},
{tHrefsq, tGhrefsq, sqHtmlMatch, sqGuard, sqHtml, false}},
xmlMatchers: []absurlMatcher{
{tSrcdq, tGrcdq, dqXmlMatch, dqXmlGuard, dqXml, false},
{tSrcsq, tGsrcsq, sqXmlMatch, sqXmlGuard, sqXml, false},
{tHrefdq, tGhrefdq, dqXmlMatch, dqXmlGuard, dqXml, false},
{tHrefsq, tGhrefsq, sqXmlMatch, sqXmlGuard, sqXml, false},
}}
}
func (au *absurlReplacer) replaceInHtml(content []byte) []byte {
return doReplace(content, au.htmlMatchers)
}
func (au *absurlReplacer) replaceInXml(content []byte) []byte {
return doReplace(content, au.xmlMatchers)
}