Return a projectile-dirconfig struct from the parser

Replace the positional (KEEP IGNORE ENSURE) triple with a
cl-defstruct. Every internal call site used car/cadr/caddr to pull
out a slot, which is unreadable and error-prone — slot accessors
make the intent explicit and let cl-defstruct grow a fourth field
later without touching every consumer.

Existing callers that compared against the raw triple (a couple of
internal helper tests) are updated to construct the struct with
make-projectile-dirconfig.

3 files changed, 75 insertions, 47 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 40a5c62..e4e33a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### Changes
+
+* `projectile-parse-dirconfig-file' now returns a `projectile-dirconfig' struct (with `keep', `ignore', and `ensure' slots) instead of a positional 3-tuple. External callers should use the accessors (`projectile-dirconfig-keep' etc.) rather than `car'/`cadr'/`caddr'.
+
 ### New features
 
 * Warn once per session when `projectile-indexing-method' is `alien' but the project has a non-empty `.projectile' file, so users notice their dirconfig rules are being bypassed. Controlled by the new `projectile-warn-when-dirconfig-is-ignored' option.
diff --git a/projectile.el b/projectile.el
index 7f2b754..dd6fce0 100644
--- a/projectile.el
+++ b/projectile.el
@@ -1516,8 +1516,10 @@ If PROJECT is not specified acts on the current project."
 ;;; Project indexing
 (defun projectile-get-project-directories (project-dir)
   "Get the list of PROJECT-DIR directories that are of interest to the user."
-  (mapcar (lambda (subdir) (concat project-dir subdir))
-          (or (car (projectile-parse-dirconfig-file)) '(""))))
+  (let* ((cfg (projectile-parse-dirconfig-file))
+         (keep (and cfg (projectile-dirconfig-keep cfg))))
+    (mapcar (lambda (subdir) (concat project-dir subdir))
+            (or keep '("")))))
 
 (defun projectile--directory-p (directory)
   "Checks if DIRECTORY is a string designating a valid directory."
@@ -2101,13 +2103,23 @@ Unignored files are not included."
 Unignored directories are not included."
   (seq-filter 'file-directory-p (projectile-project-ignored)))
 
+(defun projectile--dirconfig-ignore ()
+  "Return the IGNORE entries from the project's dirconfig, or nil."
+  (when-let* ((cfg (projectile-parse-dirconfig-file)))
+    (projectile-dirconfig-ignore cfg)))
+
+(defun projectile--dirconfig-ensure ()
+  "Return the ENSURE entries from the project's dirconfig, or nil."
+  (when-let* ((cfg (projectile-parse-dirconfig-file)))
+    (projectile-dirconfig-ensure cfg)))
+
 (defun projectile-paths-to-ignore ()
   "Return a list of ignored project paths."
-  (projectile-normalise-paths (cadr (projectile-parse-dirconfig-file))))
+  (projectile-normalise-paths (projectile--dirconfig-ignore)))
 
 (defun projectile-patterns-to-ignore ()
   "Return a list of relative file patterns."
-  (projectile-normalise-patterns (cadr (projectile-parse-dirconfig-file))))
+  (projectile-normalise-patterns (projectile--dirconfig-ignore)))
 
 (defun projectile-project-ignored ()
   "Return list of project ignored files/directories.
@@ -2151,7 +2163,7 @@ Unignored files/directories are not included."
 
 (defun projectile-paths-to-ensure ()
   "Return a list of unignored project paths."
-  (projectile-normalise-paths (caddr (projectile-parse-dirconfig-file))))
+  (projectile-normalise-paths (projectile--dirconfig-ensure)))
 
 (defun projectile-files-to-ensure ()
   (let ((default-directory (projectile-project-root)))
@@ -2160,7 +2172,7 @@ Unignored files/directories are not included."
 
 (defun projectile-patterns-to-ensure ()
   "Return a list of relative file patterns."
-  (projectile-normalise-patterns (caddr (projectile-parse-dirconfig-file))))
+  (projectile-normalise-patterns (projectile--dirconfig-ensure)))
 
 (defun projectile-filtering-patterns ()
   (cons (projectile-patterns-to-ignore)
@@ -2176,6 +2188,15 @@ Unignored files/directories are not included."
   "Return the absolute path to the project's dirconfig file."
   (expand-file-name projectile-dirconfig-file (projectile-project-root)))
 
+(cl-defstruct projectile-dirconfig
+  "Parsed contents of a project's dirconfig file.
+KEEP is the list of subdirectories to restrict the project to (as
+returned with a trailing slash).  IGNORE and ENSURE are the lists
+of files or directories to ignore and to forcibly include,
+respectively.  All slots default to nil, which represents \"no
+file present or no entries of this kind\"."
+  (keep nil) (ignore nil) (ensure nil))
+
 (defun projectile--warn-glob-in-keep-entry (entry dirconfig)
   "Warn that ENTRY in DIRCONFIG looks like a glob pattern after a `+'.
 The `+' prefix is for subdirectories only; the parser silently coerces
@@ -2190,7 +2211,7 @@ or move the pattern to a `-'/`!' rule."
 
 (defun projectile--parse-dirconfig-file-uncached ()
   "Parse the dirconfig file without caching.
-Returns a list of (KEEP IGNORE ENSURE) or nil if the file doesn't exist."
+Return a `projectile-dirconfig' or nil if the file doesn't exist."
   (let (keep ignore ensure (dirconfig (projectile-dirconfig-file)))
     (when (projectile-file-exists-p dirconfig)
       (with-temp-buffer
@@ -2216,20 +2237,19 @@ Returns a list of (KEEP IGNORE ENSURE) or nil if the file doesn't exist."
         (dolist (entry trimmed-keep)
           (when (string-match-p "[*?[]" entry)
             (projectile--warn-glob-in-keep-entry entry dirconfig)))
-        (list (mapcar #'file-name-as-directory trimmed-keep)
-              (mapcar #'string-trim
-                      (delete "" (reverse ignore)))
-              (mapcar #'string-trim
-                      (delete "" (reverse ensure))))))))
+        (make-projectile-dirconfig
+         :keep (mapcar #'file-name-as-directory trimmed-keep)
+         :ignore (mapcar #'string-trim (delete "" (reverse ignore)))
+         :ensure (mapcar #'string-trim (delete "" (reverse ensure))))))))
 
 (defun projectile-parse-dirconfig-file ()
-  "Parse project ignore file and return directories to ignore and keep.
+  "Parse project ignore file and return its rules.
 
-The return value is a list of three elements: the car is the list
-of directories to keep, the cadr is the list of files or
-directories to ignore, and the caddr is the list of files or
-directories to ensure (i.e. forcibly include even when otherwise
-ignored).
+The return value is a `projectile-dirconfig' struct with three
+slots: KEEP (subdirectories to restrict the project to), IGNORE
+(files or directories to skip), and ENSURE (files or directories
+to forcibly include even when otherwise ignored).  When the file
+does not exist, the return value is nil.
 
 Lines are dispatched on their first non-whitespace character:
 
diff --git a/test/projectile-test.el b/test/projectile-test.el
index 7e1e2a1..30ddaa3 100644
--- a/test/projectile-test.el
+++ b/test/projectile-test.el
@@ -534,22 +534,23 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
     (spy-on 'insert-file-contents :and-call-fake
             (lambda (filename)
               (save-excursion (insert "\n-exclude\n+include\n#may-be-a-comment\nno-prefix\n left-wspace\nright-wspace\t\n"))))
-    (expect (projectile-parse-dirconfig-file) :to-equal '(("include/")
-                                                          ("exclude"
-							   "#may-be-a-comment"
-							   "no-prefix"
-							   "left-wspace"
-							   "right-wspace")
-                                                          nil))
+    (expect (projectile-parse-dirconfig-file)
+            :to-equal (make-projectile-dirconfig
+                       :keep '("include/")
+                       :ignore '("exclude"
+                                 "#may-be-a-comment"
+                                 "no-prefix"
+                                 "left-wspace"
+                                 "right-wspace")))
     ;; same test - but with comment lines enabled using prefix '#'
     (let ((projectile-dirconfig-comment-prefix ?#))
-      (expect (projectile-parse-dirconfig-file) :to-equal '(("include/")
-							    ("exclude"
-							     "no-prefix"
-							     "left-wspace"
-							     "right-wspace")
-							    nil)))
-    )
+      (expect (projectile-parse-dirconfig-file)
+              :to-equal (make-projectile-dirconfig
+                         :keep '("include/")
+                         :ignore '("exclude"
+                                   "no-prefix"
+                                   "left-wspace"
+                                   "right-wspace")))))
   (it "skips leading whitespace before dispatching on the prefix"
     (spy-on 'file-exists-p :and-return-value t)
     (spy-on 'insert-file-contents :and-call-fake
@@ -560,9 +561,10 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
                         " !indented-ensure\n"
                         "  no-prefix-indented\n"))))
     (expect (projectile-parse-dirconfig-file)
-            :to-equal '(("indented-include/")
-                        ("indented-exclude" "no-prefix-indented")
-                        ("indented-ensure"))))
+            :to-equal (make-projectile-dirconfig
+                       :keep '("indented-include/")
+                       :ignore '("indented-exclude" "no-prefix-indented")
+                       :ensure '("indented-ensure"))))
   (it "treats indented comment-prefix lines as comments"
     (spy-on 'file-exists-p :and-return-value t)
     (spy-on 'insert-file-contents :and-call-fake
@@ -572,7 +574,7 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
                         "-keep-this\n"))))
     (let ((projectile-dirconfig-comment-prefix ?#))
       (expect (projectile-parse-dirconfig-file)
-              :to-equal '(nil ("keep-this") nil))))
+              :to-equal (make-projectile-dirconfig :ignore '("keep-this")))))
   (it "warns when a + keep entry contains glob metacharacters"
     (spy-on 'file-exists-p :and-return-value t)
     (spy-on 'insert-file-contents :and-call-fake
@@ -613,9 +615,10 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
                   "stale-pattern\n"))
         (spy-on 'projectile-project-root :and-return-value root)
         (expect (projectile-parse-dirconfig-file)
-                :to-equal '(("/src/")
-                            ("/build" "stale-pattern")
-                            ("/build/keepme")))))))
+                :to-equal (make-projectile-dirconfig
+                           :keep '("/src/")
+                           :ignore '("/build" "stale-pattern")
+                           :ensure '("/build/keepme")))))))
   (it "round-trips non-ASCII paths through the parser"
     (projectile-test-with-sandbox
      (projectile-test-with-files
@@ -627,9 +630,9 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
                   "+/プロジェクト\n"))
         (spy-on 'projectile-project-root :and-return-value root)
         (expect (projectile-parse-dirconfig-file)
-                :to-equal '(("/プロジェクト/")
-                            ("héllo/wörld")
-                            nil))))))
+                :to-equal (make-projectile-dirconfig
+                           :keep '("/プロジェクト/")
+                           :ignore '("héllo/wörld")))))))
   (it "tolerates a trailing line without a final newline"
     (projectile-test-with-sandbox
      (projectile-test-with-files
@@ -638,7 +641,7 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
         (with-temp-file (expand-file-name ".projectile" root)
           (insert "-foo\n-bar"))
         (spy-on 'projectile-project-root :and-return-value root)
-        (expect (cadr (projectile-parse-dirconfig-file))
+        (expect (projectile-dirconfig-ignore (projectile-parse-dirconfig-file))
                 :to-equal '("foo" "bar")))))))
 
 (describe "dirconfig cache"
@@ -667,14 +670,14 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
              (dirconfig (expand-file-name ".projectile" root)))
         (with-temp-file dirconfig (insert "-foo\n"))
         (spy-on 'projectile-project-root :and-return-value root)
-        (expect (cadr (projectile-parse-dirconfig-file))
+        (expect (projectile-dirconfig-ignore (projectile-parse-dirconfig-file))
                 :to-equal '("foo"))
         ;; Force a distinct mtime — file-attribute-modification-time has
         ;; second-level resolution on some filesystems.
         (set-file-times dirconfig (time-add (current-time) 5))
         (with-temp-file dirconfig (insert "-bar\n"))
         (set-file-times dirconfig (time-add (current-time) 5))
-        (expect (cadr (projectile-parse-dirconfig-file))
+        (expect (projectile-dirconfig-ignore (projectile-parse-dirconfig-file))
                 :to-equal '("bar"))))))
   (it "returns nil and does not cache when the dirconfig file is absent"
     (projectile-test-with-sandbox
@@ -766,11 +769,12 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
 (describe "projectile-get-project-directories"
   (it "gets the list of project directories"
     (spy-on 'projectile-project-root :and-return-value "/my/root/")
-    (spy-on 'projectile-parse-dirconfig-file :and-return-value '(nil))
+    (spy-on 'projectile-parse-dirconfig-file :and-return-value nil)
     (expect (projectile-get-project-directories "/my/root") :to-equal '("/my/root")))
   (it "gets the list of project directories with dirs to keep"
     (spy-on 'projectile-project-root :and-return-value "/my/root/")
-    (spy-on 'projectile-parse-dirconfig-file :and-return-value '(("foo" "bar/baz")))
+    (spy-on 'projectile-parse-dirconfig-file
+            :and-return-value (make-projectile-dirconfig :keep '("foo" "bar/baz")))
     (expect (projectile-get-project-directories "/my/root/") :to-equal '("/my/root/foo" "/my/root/bar/baz"))))
 
 (describe "projectile-dir-files"