From c9de59a39566a5df46aa39ef93348487bb2948aa Mon Sep 17 00:00:00 2001
From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Date: Fri, 19 Jan 2024 10:33:47 +0300
Subject: [PATCH] Support a local repo as URL in treesit-language-source-alist

Sometimes people may need to bisect to find specific revision in a
grammar repo. In this case they'd want to point the URL to the local
repo to avoid cloning it on every rebuild. So add support for full
path in treesit-language-source-alist.

* lisp/treesit.el (treesit--install-language-grammar-1): test if URL
starts with / meaning that the URL is a local path. Then if it is,
avoid cloning the repo and removing the path on success.
(treesit--git-clone-repo): factor out the code for cloning to a separate
function.
(treesit--git-checkout-branch): a helper to checkout the revision for
cases where we didn't clone the repo but want it to point the
revision.
---
 lisp/treesit.el | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/lisp/treesit.el b/lisp/treesit.el
index c8b473c7bb8..11631e68793 100644
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -3417,7 +3417,7 @@ treesit-language-source-alist
     (LANG . (URL REVISION SOURCE-DIR CC C++))
 
 Only LANG and URL are mandatory.  LANG is the language symbol.
-URL is the Git repository URL for the grammar.
+URL is the Git repository URL or full path for the grammar.
 
 REVISION is the Git tag or branch of the desired version,
 defaulting to the latest default branch.
@@ -3551,6 +3551,23 @@ treesit--call-process-signal
                                  (buffer-string)))
     (erase-buffer)))
 
+(defun treesit--git-checkout-branch (repo-path revision)
+  "Checkout `revision' in a repo located in `repo-path'"
+  (treesit--call-process-signal
+   "git" nil t nil "-C" repo-path "checkout" revision))
+
+(defun treesit--git-clone-repo (url revision workdir)
+  "Clone repo pointed by `url' at commit `revision' to `workdir'"
+  (message "Cloning repository")
+  ;; git clone xxx --depth 1 --quiet [-b yyy] workdir
+  (if revision
+      (treesit--call-process-signal
+       "git" nil t nil "clone" url "--depth" "1" "--quiet"
+       "-b" revision workdir)
+    (treesit--call-process-signal
+     "git" nil t nil "clone" url "--depth" "1" "--quiet"
+     workdir)))
+
 (defun treesit--install-language-grammar-1
     (out-dir lang url &optional revision source-dir cc c++)
   "Install and compile a tree-sitter language grammar library.
@@ -3564,8 +3581,10 @@ treesit--install-language-grammar-1
 `treesit-language-source-alist'.  If anything goes wrong, this
 function signals an error."
   (let* ((lang (symbol-name lang))
+         ;; don't clone if url is a local path
+         (url-is-path (string-prefix-p "/" url))
          (default-directory (make-temp-file "treesit-workdir" t))
-         (workdir (expand-file-name "repo"))
+         (workdir (if url-is-path url (expand-file-name "repo")))
          (source-dir (expand-file-name (or source-dir "src") workdir))
          (cc (or cc (seq-find #'executable-find '("cc" "gcc" "c99"))
                  ;; If no C compiler found, just use cc and let
@@ -3580,15 +3599,10 @@ treesit--install-language-grammar-1
          (lib-name (concat "libtree-sitter-" lang soext)))
     (unwind-protect
         (with-temp-buffer
-          (message "Cloning repository")
-          ;; git clone xxx --depth 1 --quiet [-b yyy] workdir
-          (if revision
-              (treesit--call-process-signal
-               "git" nil t nil "clone" url "--depth" "1" "--quiet"
-               "-b" revision workdir)
-            (treesit--call-process-signal
-             "git" nil t nil "clone" url "--depth" "1" "--quiet"
-             workdir))
+          (if url-is-path
+              (when revision
+                (treesit--git-checkout-branch url revision))
+            (treesit--git-clone-repo url revision workdir))
           ;; We need to go into the source directory because some
           ;; header files use relative path (#include "../xxx").
           ;; cd "${sourcedir}"
@@ -3635,7 +3649,7 @@ treesit--install-language-grammar-1
             ;; Ignore errors, in case the old version is still used.
             (ignore-errors (delete-file old-fname)))
           (message "Library installed to %s/%s" out-dir lib-name))
-      (when (file-exists-p workdir)
+      (when (and (not url-is-path) (file-exists-p workdir))
         (delete-directory workdir t)))))
 
 ;;; Etc
-- 
2.43.0