hugo/hugolib/shortcode.go
bep 55fcd2f30f Shortcode rewrite, take 2
This commit contains a restructuring and partial rewrite of the shortcode handling.

Prior to this commit rendering of the page content was mingled with handling of the shortcodes. This led to several oddities.

The new flow is:

1. Shortcodes are extracted from page and replaced with placeholders.
2. Shortcodes are processed and rendered
3. Page is processed
4. The placeholders are replaced with the rendered shortcodes

The handling of summaries is also made simpler by this.

This commit also introduces some other chenges:

1. distinction between shortcodes that need further processing and those who do not:

* `{{< >}}`: Typically raw HTML. Will not be processed.
* `{{% %}}`: Will be processed by the page's markup engine (Markdown or (infuture) Asciidoctor)

The above also involves a new shortcode-parser, with lexical scanning inspired by Rob Pike's talk called "Lexical Scanning in Go",
which should be easier to understand, give better error messages and perform better.

2. If you want to exclude a shortcode from being processed (for documentation etc.), the inner part of the shorcode must be commented out, i.e. `{{%/* movie 47238zzb */%}}`. See the updated shortcode section in the documentation for further examples.

The new parser supports nested shortcodes. This isn't new, but has two related design choices worth mentioning:

* The shortcodes will be rendered individually, so If both `{{< >}}` and `{{% %}}` are used in the nested hierarchy, one will be passed through the page's markdown processor, the other not.
* To avoid potential costly overhead of always looking far ahead for a possible closing tag, this implementation looks at the template itself, and is branded as a container with inner content if it contains a reference to `.Inner`

Fixes #565
Fixes #480
Fixes #461

And probably some others.
2014-11-17 18:32:06 -05:00

451 lines
12 KiB
Go

// Copyright © 2013-14 Steve Francia <spf@spf13.com>.
//
// Licensed under the Simple Public 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://opensource.org/licenses/Simple-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 hugolib
import (
"bytes"
"fmt"
"github.com/spf13/hugo/helpers"
jww "github.com/spf13/jwalterweatherman"
"html/template"
"reflect"
"regexp"
"strconv"
"strings"
)
type ShortcodeFunc func([]string) string
type Shortcode struct {
Name string
Func ShortcodeFunc
}
type ShortcodeWithPage struct {
Params interface{}
Inner template.HTML
Page *Page
}
func (scp *ShortcodeWithPage) Get(key interface{}) interface{} {
if reflect.ValueOf(scp.Params).Len() == 0 {
return nil
}
var x reflect.Value
switch key.(type) {
case int64, int32, int16, int8, int:
if reflect.TypeOf(scp.Params).Kind() == reflect.Map {
return "error: cannot access named params by position"
} else if reflect.TypeOf(scp.Params).Kind() == reflect.Slice {
x = reflect.ValueOf(scp.Params).Index(int(reflect.ValueOf(key).Int()))
}
case string:
if reflect.TypeOf(scp.Params).Kind() == reflect.Map {
x = reflect.ValueOf(scp.Params).MapIndex(reflect.ValueOf(key))
if !x.IsValid() {
return ""
}
} else if reflect.TypeOf(scp.Params).Kind() == reflect.Slice {
if reflect.ValueOf(scp.Params).Len() == 1 && reflect.ValueOf(scp.Params).Index(0).String() == "" {
return nil
}
return "error: cannot access positional params by string name"
}
}
switch x.Kind() {
case reflect.String:
return x.String()
case reflect.Int64, reflect.Int32, reflect.Int16, reflect.Int8, reflect.Int:
return x.Int()
default:
return x
}
}
// Note - this value must not contain any markup syntax
const shortcodePlaceholderPrefix = "HUGOSHORTCODE"
type shortcode struct {
name string
inner []interface{} // string or nested shortcode
params interface{} // map or array
err error
doMarkup bool
}
func (sc shortcode) String() string {
// for testing (mostly), so any change here will break tests!
return fmt.Sprintf("%s(%q, %t){%s}", sc.name, sc.params, sc.doMarkup, sc.inner)
}
// all in one go: extract, render and replace
// only used for testing
func ShortcodesHandle(stringToParse string, page *Page, t Template) string {
tmpContent, tmpShortcodes := extractAndRenderShortcodes(stringToParse, page, t)
if len(tmpShortcodes) > 0 {
tmpContentWithTokensReplaced, err := replaceShortcodeTokens([]byte(tmpContent), shortcodePlaceholderPrefix, -1, true, tmpShortcodes)
if err != nil {
jww.ERROR.Printf("Fail to replace short code tokens in %s:\n%s", page.BaseFileName(), err.Error())
} else {
return string(tmpContentWithTokensReplaced)
}
}
return string(tmpContent)
}
var isInnerShortcodeCache = make(map[string]bool)
// to avoid potential costly look-aheads for closing tags we look inside the template itself
// we could change the syntax to self-closing tags, but that would make users cry
// the value found is cached
func isInnerShortcode(t *template.Template) bool {
if m, ok := isInnerShortcodeCache[t.Name()]; ok {
return m
}
match, _ := regexp.MatchString("{{.*?\\.Inner.*?}}", t.Tree.Root.String())
isInnerShortcodeCache[t.Name()] = match
return match
}
func createShortcodePlaceholder(id int) string {
return fmt.Sprintf("<div>%s-%d</div>", shortcodePlaceholderPrefix, id)
}
func renderShortcodes(sc shortcode, p *Page, t Template) string {
tokenizedRenderedShortcodes := make(map[string](string))
startCount := 0
shortcodes := renderShortcode(sc, tokenizedRenderedShortcodes, startCount, p, t)
// placeholders will be numbered from 1.. and top down
for i := 1; i <= len(tokenizedRenderedShortcodes); i++ {
placeHolder := createShortcodePlaceholder(i)
shortcodes = strings.Replace(shortcodes, placeHolder, tokenizedRenderedShortcodes[placeHolder], 1)
}
return shortcodes
}
func renderShortcode(sc shortcode, tokenizedShortcodes map[string](string), cnt int, p *Page, t Template) string {
var data = &ShortcodeWithPage{Params: sc.params, Page: p}
tmpl := GetTemplate(sc.name, t)
if tmpl == nil {
jww.ERROR.Printf("Unable to locate template for shortcode '%s' in page %s", sc.name, p.BaseFileName())
return ""
}
if len(sc.inner) > 0 {
var inner string
for _, innerData := range sc.inner {
switch innerData.(type) {
case string:
inner += innerData.(string)
case shortcode:
// nested shortcodes will be rendered individually, replace them with temporary numbered tokens
cnt++
placeHolder := createShortcodePlaceholder(cnt)
renderedContent := renderShortcode(innerData.(shortcode), tokenizedShortcodes, cnt, p, t)
tokenizedShortcodes[placeHolder] = renderedContent
inner += placeHolder
default:
jww.ERROR.Printf("Illegal state on shortcode rendering of '%s' in page %s. Illegal type in inner data: %s ",
sc.name, p.BaseFileName(), reflect.TypeOf(innerData))
return ""
}
}
if sc.doMarkup {
data.Inner = template.HTML(helpers.RenderBytes([]byte(inner), p.guessMarkupType(), p.UniqueId()))
} else {
data.Inner = template.HTML(inner)
}
}
return ShortcodeRender(tmpl, data)
}
func extractAndRenderShortcodes(stringToParse string, p *Page, t Template) (string, map[string]string) {
content, shortcodes, err := extractShortcodes(stringToParse, p, t)
renderedShortcodes := make(map[string]string)
if err != nil {
// try to render what we have whilst logging the error
jww.ERROR.Println(err.Error())
}
for key, sc := range shortcodes {
if sc.err != nil {
// need to have something to replace with
renderedShortcodes[key] = ""
} else {
renderedShortcodes[key] = renderShortcodes(sc, p, t)
}
}
return content, renderedShortcodes
}
// pageTokens state:
// - before: positioned just before the shortcode start
// - after: shortcode(s) consumed (plural when they are nested)
func extractShortcode(pt *pageTokens, p *Page, t Template) (shortcode, error) {
sc := shortcode{}
var isInner = false
var currItem item
var cnt = 0
Loop:
for {
currItem = pt.next()
switch currItem.typ {
case tLeftDelimScWithMarkup, tLeftDelimScNoMarkup:
next := pt.peek()
if next.typ == tScClose {
continue
}
if cnt > 0 {
// nested shortcode; append it to inner content
pt.backup3(currItem, next)
nested, err := extractShortcode(pt, p, t)
if err == nil {
sc.inner = append(sc.inner, nested)
} else {
return sc, err
}
} else {
sc.doMarkup = currItem.typ == tLeftDelimScWithMarkup
}
cnt++
case tRightDelimScWithMarkup, tRightDelimScNoMarkup:
// we trust the template on this:
// if there's no inner, we're done
if !isInner {
return sc, nil
}
case tScClose:
if !isInner {
next := pt.peek()
if next.typ == tError {
// return that error, more specific
continue
}
return sc, fmt.Errorf("Shortcode '%s' has no .Inner, yet a closing tag was provided", next.val)
}
pt.consume(2)
return sc, nil
case tText:
sc.inner = append(sc.inner, currItem.val)
case tScName:
sc.name = currItem.val
tmpl := GetTemplate(sc.name, t)
if tmpl == nil {
return sc, fmt.Errorf("Unable to locate template for shortcode '%s' in page %s", sc.name, p.BaseFileName())
}
isInner = isInnerShortcode(tmpl)
case tScParam:
if !pt.isValueNext() {
continue
} else if pt.peek().typ == tScParamVal {
// named params
if sc.params == nil {
params := make(map[string]string)
params[currItem.val] = pt.next().val
sc.params = params
} else {
params := sc.params.(map[string]string)
params[currItem.val] = pt.next().val
}
} else {
// positional params
if sc.params == nil {
var params []string
params = append(params, currItem.val)
sc.params = params
} else {
params := sc.params.([]string)
params = append(params, currItem.val)
sc.params = params
}
}
case tError, tEOF:
// handled by caller
pt.backup()
break Loop
}
}
return sc, nil
}
func extractShortcodes(stringToParse string, p *Page, t Template) (string, map[string]shortcode, error) {
shortCodes := make(map[string]shortcode)
startIdx := strings.Index(stringToParse, "{{")
// short cut for docs with no shortcodes
if startIdx < 0 {
return stringToParse, shortCodes, nil
}
// the parser takes a string;
// since this is an internal API, it could make sense to use the mutable []byte all the way, but
// it seems that the time isn't really spent in the byte copy operations, and the impl. gets a lot cleaner
pt := &pageTokens{lexer: newShortcodeLexer("parse-page", stringToParse, pos(startIdx))}
id := 1 // incremented id, will be appended onto temp. shortcode placeholders
var result bytes.Buffer
// the parser is guaranteed to return items in proper order or fail, so …
// … it's safe to keep some "global" state
var currItem item
var currShortcode shortcode
var err error
Loop:
for {
currItem = pt.next()
switch currItem.typ {
case tText:
result.WriteString(currItem.val)
case tLeftDelimScWithMarkup, tLeftDelimScNoMarkup:
// let extractShortcode handle left delim (will do so recursively)
pt.backup()
if currShortcode, err = extractShortcode(pt, p, t); err != nil {
return result.String(), shortCodes, err
}
if currShortcode.params == nil {
currShortcode.params = make([]string, 0)
}
// wrap it in a block level element to let it be left alone by the markup engine
placeHolder := createShortcodePlaceholder(id)
result.WriteString(placeHolder)
shortCodes[placeHolder] = currShortcode
id++
case tEOF:
break Loop
case tError:
err := fmt.Errorf("%s:%d: %s",
p.BaseFileName(), (p.lineNumRawContentStart() + pt.lexer.lineNum() - 1), currItem)
currShortcode.err = err
return result.String(), shortCodes, err
}
}
return result.String(), shortCodes, nil
}
// Replace prefixed shortcode tokens (HUGOSHORTCODE-1, HUGOSHORTCODE-2) with the real content.
// This assumes that all tokens exist in the input string and that they are in order.
// numReplacements = -1 will do len(replacements), and it will always start from the beginning (1)
// wrappendInDiv = true means that the token is wrapped in a <div></div>
func replaceShortcodeTokens(source []byte, prefix string, numReplacements int, wrappedInDiv bool, replacements map[string]string) ([]byte, error) {
if numReplacements < 0 {
numReplacements = len(replacements)
}
if numReplacements == 0 {
return source, nil
}
newLen := len(source)
for i := 1; i <= numReplacements; i++ {
key := prefix + "-" + strconv.Itoa(i)
if wrappedInDiv {
key = "<div>" + key + "</div>"
}
val := []byte(replacements[key])
newLen += (len(val) - len(key))
}
buff := make([]byte, newLen)
width := 0
start := 0
for i := 0; i < numReplacements; i++ {
tokenNum := i + 1
oldVal := prefix + "-" + strconv.Itoa(tokenNum)
if wrappedInDiv {
oldVal = "<div>" + oldVal + "</div>"
}
newVal := []byte(replacements[oldVal])
j := start
k := bytes.Index(source[start:], []byte(oldVal))
if k < 0 {
// this should never happen, but let the caller decide to panic or not
return nil, fmt.Errorf("illegal state in content; shortcode token #%d is missing or out of order", tokenNum)
}
j += k
width += copy(buff[width:], source[start:j])
width += copy(buff[width:], newVal)
start = j + len(oldVal)
}
width += copy(buff[width:], source[start:])
return buff[0:width], nil
}
func GetTemplate(name string, t Template) *template.Template {
if x := t.Lookup("shortcodes/" + name + ".html"); x != nil {
return x
}
if x := t.Lookup("theme/shortcodes/" + name + ".html"); x != nil {
return x
}
return t.Lookup("_internal/shortcodes/" + name + ".html")
}
func ShortcodeRender(tmpl *template.Template, data *ShortcodeWithPage) string {
buffer := new(bytes.Buffer)
err := tmpl.Execute(buffer, data)
if err != nil {
jww.ERROR.Println("error processing shortcode", tmpl.Name(), "\n ERR:", err)
jww.WARN.Println(data)
}
return buffer.String()
}