af25eaa677
- POST /_journal/api/v1/images/alt {dry_run, changes} sets alt on the
matching img of default or translated content through the tokenizer,
all or nothing (422), with a RecordSaved per changed post
- MCP journal_get_settings, journal_update_settings, journal_fix_headings
(manage_settings) and journal_set_image_alt (access_posts, destructive)
- journal:fix-headings help names its output and the refusal
93 lines
2.2 KiB
Go
93 lines
2.2 KiB
Go
package classes
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import (
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"bytes"
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"strings"
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xhtml "golang.org/x/net/html"
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)
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// SetImageAlt sets the alt attribute of every img in html whose src
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// attribute (unescaped) equals src, adding it when missing. It returns the
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// new HTML, the number of matching images and the alt the first match had
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// (nil when it had none). It works on the x/net/html tokenizer: a matching
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// img tag is written again from its token, so every attribute value,
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// alt included, is escaped by the tokenizer and never concatenated; every
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// other byte of html is copied as it is. An empty alt marks a decorative
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// image (alt="").
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func SetImageAlt(html, src, alt string) (string, int, *string) {
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if src == "" || !containsFold(html, "<img") {
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return html, 0, nil
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}
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z := xhtml.NewTokenizer(strings.NewReader(html))
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var b bytes.Buffer
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b.Grow(len(html) + len(alt))
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matches := 0
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var old *string
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for {
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tt := z.Next()
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if tt == xhtml.ErrorToken {
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break
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}
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raw := z.Raw()
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if tt == xhtml.StartTagToken || tt == xhtml.SelfClosingTagToken {
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// Raw is copied before Token, which reads the tag; Token is
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// the only reader of the tag (TagName would consume it).
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kept := append([]byte(nil), raw...)
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tok := z.Token()
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if tok.Data == "img" && imgSrc(tok) == src {
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prev := setAlt(&tok, alt)
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if matches == 0 {
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old = prev
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}
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matches++
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b.WriteString(tok.String())
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continue
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}
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b.Write(kept)
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continue
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}
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b.Write(raw)
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}
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if matches == 0 {
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return html, 0, nil
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}
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return b.String(), matches, old
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}
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func imgSrc(tok xhtml.Token) string {
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for _, a := range tok.Attr {
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if a.Namespace == "" && a.Key == "src" {
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return a.Val
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}
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}
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return ""
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}
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// setAlt sets tok's alt to alt and returns the previous value (nil when
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// there was none). Repeated alt attributes collapse to one.
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func setAlt(tok *xhtml.Token, alt string) *string {
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var prev *string
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attrs := tok.Attr[:0]
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set := false
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for _, a := range tok.Attr {
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if a.Namespace == "" && a.Key == "alt" {
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if prev == nil {
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v := a.Val
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prev = &v
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}
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if set {
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continue
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}
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a.Val = alt
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set = true
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}
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attrs = append(attrs, a)
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}
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if !set {
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attrs = append(attrs, xhtml.Attribute{Key: "alt", Val: alt})
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}
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tok.Attr = attrs
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return prev
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}
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