From a8143035ea71376f0e53ce784991d9cd490719ee Mon Sep 17 00:00:00 2001
From: Manuel Uberti <manuel.uberti@inventati.org>
Date: Wed, 23 Feb 2022 09:25:32 +0100
Subject: [PATCH] Add project-switch-to-buffer-conditions

* lisp/progmodes/project.el (project-switch-to-buffer-conditions):
New defcustom.
(project-switch-to-buffer):
Use it (bug#54100).
---
 lisp/progmodes/project.el | 71 +++++++++++++++++++++++++++++++--------
 1 file changed, 57 insertions(+), 14 deletions(-)

diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
index 880c5b5517..e4184c69bc 100644
--- a/lisp/progmodes/project.el
+++ b/lisp/progmodes/project.el
@@ -1112,16 +1112,17 @@ project-compile
              compilation-buffer-name-function)))
     (call-interactively #'compile)))
 
-(defun project--read-project-buffer ()
+(defun project--read-project-buffer (&optional predicate)
   (let* ((pr (project-current t))
          (current-buffer (current-buffer))
          (other-buffer (other-buffer current-buffer))
          (other-name (buffer-name other-buffer))
          (buffers (project-buffers pr))
          (predicate
-          (lambda (buffer)
-            ;; BUFFER is an entry (BUF-NAME . BUF-OBJ) of Vbuffer_alist.
-            (memq (cdr buffer) buffers))))
+          (or predicate
+              (lambda (buffer)
+                ;; BUFFER is an entry (BUF-NAME . BUF-OBJ) of Vbuffer_alist.
+                (memq (cdr buffer) buffers)))))
     (read-buffer
      "Switch to buffer: "
      (when (funcall predicate (cons other-name other-buffer))
@@ -1129,6 +1130,43 @@ project--read-project-buffer
      nil
      predicate)))
 
+(defcustom project-switch-to-buffer-conditions nil
+  "List of conditions to filter the buffers to be switched to.
+This list is used by `project-switch-to-buffer'.
+Each condition is either:
+- a regular expression, to match a buffer name,
+- a predicate function that takes a buffer object as argument
+  and returns non-nil if the buffer should be switched to,
+- a cons-cell, where the car describes how to interpret the cdr.
+  The car can be one of the following:
+  * `major-mode': the buffer is switched to if the buffer's major
+    mode is eq to the cons-cell's cdr
+  * `derived-mode': the buffer is switched to if the buffer's major
+    mode is derived from the major mode denoted by the cons-cell's
+    cdr
+  * `not': the cdr is interpreted as a negation of a condition.
+  * `and': the cdr is a list of recursive conditions, that all have
+    to be met.
+  * `or': the cdr is a list of recursive conditions, of which at
+    least one has to be met.
+
+If any of these conditions are satisfied for a buffer in the
+current project, `project-switch-to-buffer' switches to it."
+  :type '(repeat (choice regexp function symbol
+                         (cons :tag "Major mode"
+                               (const major-mode) symbol)
+                         (cons :tag "Derived mode"
+                               (const derived-mode) symbol)
+                         (cons :tag "Negation"
+                               (const not) sexp)
+                         (cons :tag "Conjunction"
+                               (const and) sexp)
+                         (cons :tag "Disjunction"
+                               (const or) sexp)))
+  :version "29.1"
+  :group 'project
+  :package-version '(project . "0.8.2"))
+
 ;;;###autoload
 (defun project-switch-to-buffer (buffer-or-name)
   "Display buffer BUFFER-OR-NAME in the selected window.
@@ -1136,7 +1174,11 @@ project-switch-to-buffer
 current project.  Two buffers belong to the same project if their
 project instances, as reported by `project-current' in each
 buffer, are identical."
-  (interactive (list (project--read-project-buffer)))
+  (interactive
+   (list (project--read-project-buffer
+          (lambda (buffer)
+            (project--buffer-check
+             (cdr buffer) project-switch-to-buffer-conditions)))))
   (switch-to-buffer buffer-or-name))
 
 ;;;###autoload
@@ -1239,11 +1281,12 @@ project--buffer-list
         (push buf bufs)))
     (nreverse bufs)))
 
-(defun project--kill-buffer-check (buf conditions)
+(defun project--buffer-check (buf conditions)
   "Check if buffer BUF matches any element of the list CONDITIONS.
-See `project-kill-buffer-conditions' for more details on the form
-of CONDITIONS."
-  (catch 'kill
+See `project-kill-buffer-conditions' or
+`project-switch-to-buffer-conditions' for more details on the
+form of CONDITIONS."
+  (catch 'match
     (dolist (c conditions)
       (when (cond
              ((stringp c)
@@ -1258,15 +1301,15 @@ project--kill-buffer-check
                (buffer-local-value 'major-mode buf)
                (cdr c)))
              ((eq (car-safe c) 'not)
-              (not (project--kill-buffer-check buf (cdr c))))
+              (not (project--buffer-check buf (cdr c))))
              ((eq (car-safe c) 'or)
-              (project--kill-buffer-check buf (cdr c)))
+              (project--buffer-check buf (cdr c)))
              ((eq (car-safe c) 'and)
               (seq-every-p
-               (apply-partially #'project--kill-buffer-check
+               (apply-partially #'project--buffer-check
                                 buf)
                (mapcar #'list (cdr c)))))
-        (throw 'kill t)))))
+        (throw 'match t)))))
 
 (defun project--buffers-to-kill (pr)
   "Return list of buffers in project PR to kill.
@@ -1274,7 +1317,7 @@ project--buffers-to-kill
 in `project-kill-buffer-conditions'."
   (let (bufs)
     (dolist (buf (project-buffers pr))
-      (when (project--kill-buffer-check buf project-kill-buffer-conditions)
+      (when (project--buffer-check buf project-kill-buffer-conditions)
         (push buf bufs)))
     bufs))
 
-- 
2.25.1