feat: Fold markdown heading (#123)

* feat: Fold markdown heading

* fix: markdown html_block

ts-fold-parsers.el

@@ -72,6 +72,9 @@
 (declare-function ts-fold-range-lua-do-loop "ts-fold.el")
 (declare-function ts-fold-range-lua-repeat "ts-fold.el")
 (declare-function ts-fold-range-make-recipe "ts-fold.el")
+(declare-function ts-fold-range-markdown-heading "ts-fold.el")
+(declare-function ts-fold-range-markdown-code-block "ts-fold.el")
+(declare-function ts-fold-range-markdown-html-block "ts-fold.el")
 (declare-function ts-fold-range-matlab-function "ts-fold.el")
 (declare-function ts-fold-range-matlab-statements "ts-fold.el")
 (declare-function ts-fold-range-matlab-blocks "ts-fold.el")
@@ -430,8 +433,9 @@
 
 (defun ts-fold-parsers-markdown ()
   "Rule set for Markdown."
-  '((fenced_code_block . (ts-fold-range-seq 2 -2))
-    (html_block        . ts-fold-range-html)))
+  '((fenced_code_block . ts-fold-range-markdown-code-block)
+    (section           . ts-fold-range-markdown-heading)
+    (html_block        . ts-fold-range-markdown-html-block)))
 
 (defun ts-fold-parsers-matlab ()
   "Rule set for MATLAB."

ts-fold-summary.el

@@ -89,7 +89,8 @@ type of content by checking the word boundary's existence."
 
 (defun ts-fold-summary--doc-extract (doc-str sym)
   "Default way to extract the doc summary from DOC-STR using SYM."
-  (let* ((lines (ts-fold-summary--extract-summary doc-str sym)) (summary (nth 0 lines)))
+  (let* ((lines (ts-fold-summary--extract-summary doc-str sym))
+         (summary (nth 0 lines)))
     (when summary (setq summary (string-trim summary)))
     (if (string-empty-p summary) nil summary)))
 
@@ -159,8 +160,8 @@ type of content by checking the word boundary's existence."
 (defun ts-fold-summary-c-macro (doc-str)
   "Parse C macro summary from DOC-STR."
   (when (ts-fold--is-face doc-str
-                          '(font-lock-preprocessor-face
-                            preproc-font-lock-preprocessor-background))
+                          '( font-lock-preprocessor-face
+                             preproc-font-lock-preprocessor-background))
     (ts-fold-summary--doc-extract doc-str "")))
 
 (defun ts-fold-summary-c (doc-str)

ts-fold-util.el

@@ -64,9 +64,13 @@ Like function `s-count-matches' but faster."
 ;; (@* "Cons" )
 ;;
 
-(defun ts-fold--cons-add (c1 c2)
-  "Addition for two cons C1 and C2."
-  (cons (+ (car c1) (car c2)) (+ (cdr c1) (cdr c2))))
+(defun ts-fold--cons-add (&rest args)
+  "Addition for list of cons ARGS."
+  (let ((v1 0) (v2 0))
+    (dolist (c args)
+      (setq v1 (+ v1 (car c))
+            v2 (+ v2 (cdr c))))
+    (cons v1 v2)))
 
 ;;
 ;; (@* "Overlay" )
@@ -86,13 +90,13 @@ Like function `s-count-matches' but faster."
 ;;
 
 (defvar ts-fold--doc-faces
-  '(font-lock-doc-face
-    font-lock-comment-face
-    font-lock-comment-delimiter-face
-    tree-sitter-hl-face:comment
-    tree-sitter-hl-face:doc
-    hl-todo
-    rst-comment)
+  '( font-lock-doc-face
+     font-lock-comment-face
+     font-lock-comment-delimiter-face
+     tree-sitter-hl-face:comment
+     tree-sitter-hl-face:doc
+     hl-todo
+     rst-comment)
   "List of face that apply for document string.")
 
 (defun ts-fold--get-face (obj trim)

ts-fold.el

@@ -547,13 +547,13 @@ then return the last iterated node.
 Argument NEXT is a boolean type.  If non-nil iterate forward; otherwise iterate
 in backward direction."
   (let* ((iter-node node) (last-node node)
-         (last-line (car (tsc-node-start-point node))) line text break
+         (last-line (car (tsc-node-start-position node))) line text break
          (line-range 1) (last-line-range 1) max-line-range
          (indentation (ts-fold--indentation (tsc-node-start-position iter-node)))
          next-indentation)
     (while (and iter-node (not break))
       (setq text (string-trim (tsc-node-text iter-node))
-            line (car (tsc-node-start-point iter-node))
+            line (car (tsc-node-start-position iter-node))
             line-range (1+ (ts-fold--count-matches "\n" text))
             max-line-range (max line-range last-line-range)
             next-indentation (ts-fold--indentation (tsc-node-start-position iter-node)))
@@ -1088,6 +1088,54 @@ more information."
               (end (tsc-node-end-position last-child)))
     (ts-fold--cons-add (cons beg end) offset)))
 
+(defun ts-fold-range-markdown-next-heading (node siblings)
+  "Return first heading from SIBLINGS with start point after NODE.
+If there is no sibling, then return nil."
+  (or
+   (seq-find
+    (lambda (n)
+      (when-let ((child (tsc-get-nth-child n 0)))
+        (and (> (tsc-node-start-position child) (tsc-node-start-position node))
+             (ts-fold--compare-type child "atx_heading"))))
+    (remove node siblings))
+   (tsc-get-next-sibling (tsc-get-parent node))))
+
+(defun ts-fold-range-markdown-heading (node offset)
+  "Define fold range for Markdown headings.
+
+For arguments NODE and OFFSET, see function `ts-fold-range-seq' for
+more information."
+  (when-let*
+      ((parent (tsc-get-parent node))
+       (head (tsc-get-nth-child node 0))
+       (beg  (tsc-node-start-position node))
+       (siblings (ts-fold-find-children parent "section"))
+       (end (1- (or (ignore-errors (tsc-node-start-position
+                                    (ts-fold-range-markdown-next-heading node siblings)))
+                    (point-max))))
+       (name (length (string-trim (or (tsc-node-text head) "")))))
+    (ts-fold--cons-add (cons beg end) (cons name 0) offset)))
+
+(defun ts-fold-range-markdown-code-block (node offset)
+  "Define fold range for Markdown code blocks.
+For arguments NODE and OFFSET, see function `ts-fold-range-seq' for
+more information."
+  (let* ((beg (1+ (tsc-node-start-position node)))
+         (end (1- (tsc-node-end-position node)))
+         (name (+ 2 (length
+                     (or (tsc-node-text (tsc-get-nth-child node 1))
+                         "")))))
+    (ts-fold--cons-add (cons beg end) (cons name -2) offset)))
+
+(defun ts-fold-range-markdown-html-block (node offset)
+  "Define fold range for Markdown `html_block'.
+
+For arguments NODE and OFFSET, see function `ts-fold-range-seq' for
+more information."
+  (let* ((beg (+ (tsc-node-start-position node) 2))
+         (end (- (tsc-node-end-position node) 3)))
+    (ts-fold--cons-add (cons beg end) offset)))
+
 (defun ts-fold-range-matlab-blocks (node offset)
   "Define fold range for MATLAB blocks.