master 3dd6b23: Propertize all shr fragment IDs as shr-target-id

[Basil L. Contovounesios]

branch: master
commit 3dd6b23cdfa64bdff2bdc9e7fbf9844a2ed6cd8f
Author: Basil L. Contovounesios <contovob@tcd.ie>
Commit: Basil L. Contovounesios <contovob@tcd.ie>

    Propertize all shr fragment IDs as shr-target-id
    
    * lisp/net/shr.el (shr-target-id): Add docstring.
    (shr-descend, shr-tag-a): Display dummy anchor characters as the
    empty string.  Give all relevant 'id' or 'name' fragment identifier
    attributes the shr-target-id text property.  This ensures that
    cached content, such as tables, retains the property across
    renders.  (Bug#40532)
    
    * lisp/net/eww.el: (eww-display-html): Adapt shr-target-id property
    search accordingly.
---
 lisp/net/eww.el | 17 +++++++++--------
 lisp/net/shr.el | 25 +++++++++++++------------
 2 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/lisp/net/eww.el b/lisp/net/eww.el
index cf31d37..2f6528d 100644
--- a/lisp/net/eww.el
+++ b/lisp/net/eww.el
@@ -25,13 +25,14 @@
 ;;; Code:
 
 (require 'cl-lib)
+(require 'mm-url)
+(require 'puny)
 (require 'shr)
+(require 'text-property-search)
+(require 'thingatpt)
 (require 'url)
 (require 'url-queue)
-(require 'thingatpt)
-(require 'mm-url)
-(require 'puny)
-(eval-when-compile (require 'subr-x)) ;; for string-trim
+(eval-when-compile (require 'subr-x))
 
 (defgroup eww nil
   "Emacs Web Wowser"
@@ -542,10 +543,10 @@ Currently this means either text/html or 
application/xhtml+xml."
          (goto-char point))
         (shr-target-id
          (goto-char (point-min))
-         (let ((point (next-single-property-change
-                       (point-min) 'shr-target-id)))
-           (when point
-             (goto-char point))))
+          (let ((match (text-property-search-forward
+                        'shr-target-id shr-target-id t)))
+            (when match
+              (goto-char (prop-match-beginning match)))))
         (t
          (goto-char (point-min))
          ;; Don't leave point inside forms, because the normal eww
diff --git a/lisp/net/shr.el b/lisp/net/shr.el
index 03260c9..a3f0496 100644
--- a/lisp/net/shr.el
+++ b/lisp/net/shr.el
@@ -185,13 +185,15 @@ and other things:
 (defvar shr-depth 0)
 (defvar shr-warning nil)
 (defvar shr-ignore-cache nil)
-(defvar shr-target-id nil)
 (defvar shr-table-separator-length 1)
 (defvar shr-table-separator-pixel-width 0)
 (defvar shr-table-id nil)
 (defvar shr-current-font nil)
 (defvar shr-internal-bullet nil)
 
+(defvar shr-target-id nil
+  "Target fragment identifier anchor.")
+
 (defvar shr-map
   (let ((map (make-sparse-keymap)))
     (define-key map "a" 'shr-show-alt-text)
@@ -526,13 +528,13 @@ size, and full-buffer size."
                (funcall function dom))
               (t
                (shr-generic dom)))
-       (when (and shr-target-id
-                  (equal (dom-attr dom 'id) shr-target-id))
+        (when-let* ((id (dom-attr dom 'id)))
          ;; If the element was empty, we don't have anything to put the
          ;; anchor on.  So just insert a dummy character.
          (when (= start (point))
-           (insert "*"))
-         (put-text-property start (1+ start) 'shr-target-id shr-target-id))
+            (insert ?*)
+            (put-text-property (1- (point)) (point) 'display ""))
+          (put-text-property start (1+ start) 'shr-target-id id))
        ;; If style is set, then this node has set the color.
        (when style
          (shr-colorize-region
@@ -1486,14 +1488,13 @@ ones, in case fg and bg are nil."
        (start (point))
        shr-start)
     (shr-generic dom)
-    (when (and shr-target-id
-              (equal (dom-attr dom 'name) shr-target-id))
-      ;; We have a zero-length <a name="foo"> element, so just
-      ;; insert...  something.
+    (when-let* ((id (unless (dom-attr dom 'id) ; Handled by `shr-descend'.
+                      (dom-attr dom 'name))))  ; Obsolete since HTML5.
+      ;; We have an empty element, so just insert... something.
       (when (= start (point))
-       (shr-ensure-newline)
-       (insert " "))
-      (put-text-property start (1+ start) 'shr-target-id shr-target-id))
+        (insert ?\s)
+        (put-text-property (1- (point)) (point) 'display ""))
+      (put-text-property start (1+ start) 'shr-target-id id))
     (when url
       (shr-urlify (or shr-start start) (shr-expand-url url) title))))