Fix markdown-wiki-link-p overriding match data issue

[syohex]

Description

This is improved version of #590.

Related Issue

#590. CC: @srid

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have read the CONTRIBUTING.md document.
• I have updated the documentation in the README.md file if necessary.
• I have added an entry to CHANGES.md.
• I have added tests to cover my changes.
• All new and existing tests passed (using make test).

[srid]

@syohex I confirm that your change works!

However, both yours and mine doesn't work for the opposite case (of looking up a markdown file in a sibling directory of a parent). Would this be in scope for this PR, or is it a different issue?

To reproduce:

git clone [email protected]:srid/neuron.git
cd neuron/doc/
emacs -nw Guide/Plugins/Linking.md

1. Insert [[math]] in that markdown
2. C-c C-o

Instead of opening ./doc/Guide/Zettel Markdown/math.md as one would expect, it creates a new file at ./doc/Guide/Plugins/math.md.

[syohex]

I'll check later

[syohex]

Would this be in scope for this PR, or is it a different issue?

It is a different issue. Current markdown-mode searches only current directory, sub-directories and parent directories. If target file is in other than then such as ../foo/bar/baz.md, markdown-mode cannot find it. We need other changes to support that feature.

[srid]

If markdown-mode becomes project-aware (say, by looking at the project-root of project.el, which is built into emacs), then it can simply search recursively from (project-root), instead of searching from the base directory of the current buffer file.

Then we can replace both markdown-wiki-link-search-subdirectories and markdown-wiki-link-search-parent-directories with a single markdown-wiki-link-search-mode that takes one of the three values:

• 'search-subdirectories
• 'search-sub-and-parent-directories
• 'search-project-root

What do you all think?

[syohex]

Sounds good. I suppose value naming can be improved like subdirectories, sub-and-parent-directories, project (I suppose search- prefix is redundant)

However we should consider compatibility. I'm not sure we can use functions of project.el because some functions of project.el does not work non-Unix platform such as Windows.

I'll think about it.

[syohex]

Initial implementation for searching wiki links under project root.

diff --git a/markdown-mode.el b/markdown-mode.el
index f9cbd0c..f6bfab4 100644
--- a/markdown-mode.el
+++ b/markdown-mode.el
@@ -48,6 +48,8 @@
 (defvar flyspell-generic-check-word-predicate)
 (defvar electric-pair-pairs)
 
+(declare-function project-roots "project")
+
 
 ;;; Constants =================================================================
 
@@ -243,6 +245,18 @@ This is the default search behavior of Ikiwiki."
   :safe 'booleanp
   :package-version '(markdown-mode . "2.2"))
 
+(defcustom markdown-wiki-link-search-type nil
+  "Searching type for markdown wiki link."
+  :group 'markdown
+  :type '(set
+          (const :tag "search wiki link from subdirectories" sub-dir)
+          (const :tag "search wiki link from parent directory" parent-dir)
+          (const :tag "search wiki link under project root" project))
+  :package-version '(markdown-mode . "2.5"))
+
+(make-obsolete-variable 'markdown-wiki-link-search-subdirectories 'markdown-wiki-link-search-type "2.5")
+(make-obsolete-variable 'markdown-wiki-link-search-parent-directories 'markdown-wiki-link-search-type "2.5")
+
 (defcustom markdown-wiki-link-fontify-missing nil
   "When non-nil, change wiki link face according to existence of target files.
 This is expensive because it requires checking for the file each time the buffer
@@ -7830,6 +7844,17 @@ The location of the alias component depends on the value of
       (match-string-no-properties 3)
     (or (match-string-no-properties 5) (match-string-no-properties 3))))
 
+(defun markdown--wiki-link-search-types ()
+  (let ((ret (and markdown-wiki-link-search-type
+                  (cl-copy-list markdown-wiki-link-search-type))))
+    (when (and markdown-wiki-link-search-subdirectories
+               (not (memq 'sub-dir markdown-wiki-link-search-type)))
+      (push 'sub-dir ret))
+    (when (and markdown-wiki-link-search-parent-directories
+               (not (memq 'parent-dir markdown-wiki-link-search-type)))
+      (push 'parent-dir ret))
+    ret))
+
 (defun markdown-convert-wiki-link-to-filename (name)
   "Generate a filename from the wiki link NAME.
 Spaces in NAME are replaced with `markdown-link-space-sub-char'.
@@ -7847,6 +7872,7 @@ in parent directories if
                          (concat (upcase (substring basename 0 1))
                                  (downcase (substring basename 1 nil)))
                        basename))
+           (search-types (markdown--wiki-link-search-types))
            directory extension default candidates dir)
       (when buffer-file-name
         (setq directory (file-name-directory buffer-file-name)
@@ -7859,15 +7885,22 @@ in parent directories if
             (file-exists-p default))
         default)
        ;; Possibly search in subdirectories, next.
-       ((and markdown-wiki-link-search-subdirectories
+       ((and (memq 'sub-dir search-types)
              (setq candidates
                    (directory-files-recursively
                     directory (concat "^" default "$"))))
         (car candidates))
        ;; Possibly search in parent directories as a last resort.
-       ((and markdown-wiki-link-search-parent-directories
+       ((and (memq 'parent-dir search-types)
              (setq dir (locate-dominating-file directory default)))
         (concat dir default))
+       ((and (memq 'project search-types)
+             (progn
+               (require 'project)
+               (let ((roots (project-roots (project-current t))))
+                 (setq candidates
+                       (directory-files-recursively (car roots) (concat "^" default "$"))))))
+        (car candidates))
        ;; If nothing is found, return default in current directory.
        (t default)))))

[syohex]

@srid How about #592 ?

Here is sample configuration of it.

(require 'markdown-mode)
(setq markdown-enable-wiki-links t)
(setq markdown-link-space-sub-char " ")
(setq markdown-wiki-link-search-type '(project))

[srid]

@syohex It works perfectly! Tested it on my private Zettelkasten -- which is really just a directory tree of .md files (about 600 of them) -- and markdown-mode can successfully follow links from anywhere to anywhere under the project.

Once your PR gets merged, and released to elpa/melpa, I'd be happy to add markdown-mode to https://neuron.zettel.page/editor.html