Subject: [PATCH] Teach ffap to look for paths under the root of project

From: Spencer Baugh <[email-masked]>
Date: Sat, 21 Oct 2023 14:37:45 -0400

Tags: patch

This is a nice little quality of life feature.

In GNU Emacs 29.1.50 (build 12, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.15.12, Xaw scroll bars) of 2023-10-19 built on
 igm-qws-u22796a
Repository revision: 9163e634e296435aa7a78bc6b77b4ee90666d2ac
Repository branch: emacs-29
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Rocky Linux 8.8 (Green Obsidian)

Configured using:
 'configure --config-cache --with-x-toolkit=lucid
 --with-gif=ifavailable'

>From 521116073821c5259130c415640265cb25c03ef3 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <[email-masked]>
Date: Sat, 21 Oct 2023 14:35:53 -0400
Subject: [PATCH] Teach ffap to look for paths under the root of project

Now file-name-at-point-functions, which runs
ffap-guess-file-name-at-point, will pick up on a file name at point if
that file name is a path starting from the root of the project.

For example, in test/lisp/progmodes/eglot-tests.el there is the string
lisp/progmodes/eglot.el; if you put point on that and C-x C-f,
lisp/progmodes/eglot.el under the root of the Emacs repo will now be
part of future history.

* lisp/ffap.el (ffap-alist): Add entry for ffap-in-project.
(ffap-in-project): Add.
---
 lisp/ffap.el | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lisp/ffap.el b/lisp/ffap.el
index 2c99f88d505..fe0aa16c22f 100644
--- a/lisp/ffap.el
+++ b/lisp/ffap.el
@@ -734,6 +734,7 @@ ffap-locate-file
 (defvar ffap-alist
   '(
     ("" . ffap-completable)		; completion, slow on some systems
+    ("" . ffap-in-project)		; maybe in the root of the project
     ("\\.info\\'" . ffap-info)		; gzip.info
     ("\\`info/" . ffap-info-2)		; info/emacs
     ("\\`[-[:lower:]]+\\'" . ffap-info-3) ; (emacs)Top [only in the parentheses]
@@ -797,6 +798,10 @@ ffap-completable
 	 (cmp (file-name-completion (file-name-nondirectory name) dir)))
     (and cmp (concat dir cmp))))
 
+(defun ffap-in-project (name)
+  (when-let (project (project-current))
+    (file-name-concat (project-root project) name)))
+
 (defun ffap-home (name) (ffap-locate-file name t '("~")))
 
 (defun ffap-info (name)
-- 
2.39.3