tree: add more?

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Pavel Korytov 2024-09-07 00:35:23 +03:00
parent 91d7185480
commit 8d6a888221
2 changed files with 229 additions and 5 deletions

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@ -1,4 +1,5 @@
#+HUGO_SECTION: posts
#+PROPERTY: header-args:emacs-lisp :tangle load-tree.el
#+HUGO_BASE_DIR: ../
#+TITLE: Determining package dependency tree in Emacs
#+DATE: 2024-07-11
@ -15,7 +16,7 @@ The post describes how to determine package dependency tree, using the built-in
* Prior work
Somehow it has been particularly hard to find anything on that topic.
I started with advising =require= (yes, Emacs allows to do that), but then I had found the built-in [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Where-Defined.html#index-load_002dhistory][load-history]]. The variable is an alist, with each item describing one loaded library, including =require= and =provide= forms:
I started with advising =require= (yes, Emacs allows to do that), but then I had found the built-in [[https://www.gnu.org/software/emacs/manual/html_node/emacs-lisp/Where-Defined.html#index-load_002dhistory][load-history]]. The variable is an alist, with each item describing one loaded library, including =require= and =provide= forms:
#+begin_example
(("<file-name>/foo.el" (require . bar) (require . baz) (provide . foo)) ...)
#+end_example
@ -32,7 +33,7 @@ Let the key be the feature symbol, and the value the list of features which requ
Also, I'll extract the iteration over =load-history= into a macro because I want to reuse it later.
#+begin_src elisp
#+begin_src emacs-lisp
(defmacro my/load-history--iter-load-history (&rest body)
"Iterate through `load-history'.
@ -70,7 +71,7 @@ which it was required."
This graph can be converted to the tree by taking one feature as a root and traversing every possible path, excluding loops. This will create a lot of duplicate nodes, but it's fine for our purposes.
#+begin_src elisp
#+begin_src emacs-lisp
(defun my/load-history--get-feature-tree (feature-name feature-hash &optional found-features)
"Get the tree of features with FEATURE-NAME as the root.
@ -96,7 +97,7 @@ and the cdr being a list cons cell of the same kind."
(remhash feature-name found-features)))
#+end_src
This feature tree is already interesting, but for me it's also helpful to find the subset of the tree managed by [[https://github.com/jwiegley/use-package][use-package]]. For instance, I used this to figure out why opening an elisp buffer loads =org-mode= (spolier: [[https://github.com/abo-abo/lispy/blob/fe44efd21573868638ca86fc8313241148fabbe3/lispy.el#L143][lispy]] -> [[https://github.com/abo-abo/zoutline/blob/32857c6c4b9b0bcbed14d825a10b91a98d5fed0a/zoutline.el#L26][zoutline]] -> org).
This feature tree is already interesting, but for me it's also helpful to find the subset of the tree managed by [[https://github.com/jwiegley/use-package][use-package]]. For instance, I used this to figure out why opening an emacs-lisp buffer loads =org-mode= (spolier: [[https://github.com/abo-abo/lispy/blob/fe44efd21573868638ca86fc8313241148fabbe3/lispy.el#L143][lispy]] -> [[https://github.com/abo-abo/zoutline/blob/32857c6c4b9b0bcbed14d825a10b91a98d5fed0a/zoutline.el#L26][zoutline]] -> org).
Fortunately, =use-package= has built-in [[https://github.com/jwiegley/use-package?tab=readme-ov-file#gathering-statistics][statistics functionality]]. To turn it on, set the following variable:
#+begin_src emacs-lisp
@ -165,7 +166,7 @@ I'll also make a derived mode from =outline-mode= to redefine =q= and =TAB= and
Now, putting all of this together.
The completing-read function prompts the user either with a [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Named-Features.html#index-features-1][list of features]] or with the list of use-package packages.
The completing-read function prompts the user either with a [[https://www.gnu.org/software/emacs/manual/html_node/emacs-lisp/Named-Features.html#index-features-1][list of features]] or with the list of use-package packages.
#+begin_src emacs-lisp
(defun my/completing-read-features-or-packages ()
@ -236,3 +237,49 @@ managed by `use-package'."
#+end_src
* Usage and results
So we have two entrypoints:
- =M-x my/load-history-feature-dependents= to list features / packages that depend on the selected one;
- =M-x my/load-history-feature-dependencies= to list features / packages that the selected one depends on.
For instance, running =C-u M-x my/load-history-feature-dependents= on =dired= on my config yields the following:
#+begin_example
,* dired
,** counsel...
,** doc-view...
,** telega...
,** diredfl...
,** dired-subtree...
,** all-the-icons-dired...
,** dired-git-info...
,** avy-dired...
,** org-contacts...
,** org-ref...
,** notmuch...
,** magit...
,** code-review...
,** lyrics-fetcher...
#+end_example
Apparently, [[https://github.com/abo-abo/swiper/blob/master/counsel.el#L48][counsel is responsible]] for loading =dired= at startup. The package isn't merely autoloaded because I call =counsel-mode=.
If you're developing a package, here's one way to work around that. Instead of requiring every feature at the start of the package like this:
#+begin_src emacs-lisp
(require 'dired)
#+end_src
Use =eval-when-compile=:
#+begin_src emacs-lisp
(eval-when-compile
(require 'dired))
#+end_src
And =require= the feature where it's needed:
#+begin_src emacs-lisp
(defun my-function-with-dired ()
"Do something important with dired."
(interactive)
(require 'dired))
#+end_src
I'd guess =counsel= doesn't do this because it depends on =dired= too heavily.

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org/load-tree.el Normal file
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(defmacro my/load-history--iter-load-history (&rest body)
"Iterate through `load-history'.
The following are bound in BODY in the process:
- file-item is one item in `load-history' providing a feature, given
that it's not \"-autoloads\";
- provide-symbol is the feature name, provided by the item;
- requires is the list of feature, required by the item."
`(dolist (file-item load-history)
(let (provide-symbol requires)
(dolist (symbol-item (cdr file-item))
(pcase (car-safe symbol-item)
('require (push (cdr symbol-item) requires))
('provide (setq provide-symbol (cdr symbol-item)))))
(when (and provide-symbol
(not (string-match-p
(rx "-autoloads" eos)
(symbol-name provide-symbol))))
,@body))))
(defun my/load-history--get-feature-required-by ()
"Get the hashmap of which features were required by which.
The key is the feature name; the value is the list of features in
which it was required."
(let ((feature-required-by (make-hash-table)))
(my/load-history--iter-load-history
(dolist (require-symbol requires)
(puthash require-symbol
(cons provide-symbol
(gethash require-symbol feature-required-by))
feature-required-by)))
feature-required-by))
(defun my/load-history--get-feature-tree (feature-name feature-hash &optional found-features)
"Get the tree of features with FEATURE-NAME as the root.
FEATURE-HASH is the hashmap with features as keys and lists of
features as values.
FOUND-FEATURES is the recursive paratemer to avoid infinite loop.
The output is a cons cell, with the car being the feature name
and the cdr being a list cons cell of the same kind."
(unless found-features
(setq found-features (make-hash-table)))
(puthash feature-name t found-features)
(prog1
(cons feature-name
(mapcar
(lambda (dependent-feature-name)
(if (gethash dependent-feature-name found-features)
(cons dependent-feature-name 'loop)
(my/load-history--get-feature-tree
dependent-feature-name feature-hash found-features)))
(gethash feature-name feature-hash)))
(remhash feature-name found-features)))
(setq use-package-compute-statistics t)
(defun my/load-history--narrow-tree-by-use-package (tree)
"Leave only features managed by `use-package' in TREE."
(when (= (hash-table-count use-package-statistics) 0)
(user-error "use-package-statistics is empty"))
(if (eq (cdr tree) 'loop)
(cons (car tree) nil)
(let (res)
(dolist (child (cdr tree))
(let ((found-p (gethash (car child) use-package-statistics))
(child-narrowed (my/load-history--narrow-tree-by-use-package child)))
(if found-p
(push child-narrowed res)
(dolist (grandchild (cdr child-narrowed))
(push grandchild res)))))
(cons (car tree)
(seq-uniq
(nreverse res)
(lambda (a b)
(eq (car a) (car b))))))))
(defun my/load-history--render-feature-tree-recur (tree &optional level)
"Render the feature tree recursively.
TREE is the output of `my/load-history--get-feature-tree'. LEVEL is
the recursion level."
(unless level (setq level 1))
(insert (make-string level ?*) " " (symbol-name (car tree)))
(if (eq (cdr tree) 'loop)
(insert ": loop\n")
(insert "\n")
(dolist (feature (cdr tree))
(my/load-history--render-feature-tree-recur feature (1+ level)))))
(defvar my/load-history-tree-mode-map
(let ((map (make-sparse-keymap)))
(set-keymap-parent map outline-mode-map)
(define-key map (kbd "q") (lambda () (interactive) (quit-window t)))
(when (fboundp #'evil-define-key*)
(evil-define-key* '(normal motion) map
(kbd "TAB") #'outline-toggle-children
"q" (lambda () (interactive) (quit-window t))))
map))
(define-derived-mode my/load-history-tree-mode outline-mode "Load Tree"
"Display load tree."
(setq-local buffer-read-only t))
(defun my/completing-read-features-or-packages ()
"Read a feature name or a `use-package'-package from the minibuffer.
The choice depends on the value of the prefix argument."
(intern
(if (equal current-prefix-arg '(4))
(completing-read "Package: " (cl-loop for p being the hash-keys of
use-package-statistics
collect p))
(completing-read "Feature: " features))))
(defun my/load-history-feature-dependents (feature-name &optional narrow-use-package)
"Display the tree of features that depend on FEATURE-NAME.
If NARROW-USE-PACKAGE is non-nil, only show the features that are
managed by `use-package'."
(interactive (list (my/completing-read-features-or-packages)
(equal current-prefix-arg '(4))))
(let* ((feature-required-by (my/load-history--get-feature-required-by))
(tree (my/load-history--get-feature-tree feature-name feature-required-by))
(buffer (generate-new-buffer (format "*feature-dependents-%s*" feature-name))))
(when narrow-use-package
(setq tree (my/load-history--narrow-tree-by-use-package tree)))
(with-current-buffer buffer
(my/load-history--render-feature-tree-recur tree)
(my/load-history-tree-mode)
(goto-char (point-min)))
(switch-to-buffer buffer)))
(defun my/load-history--get-feature-requires ()
"Get the hashmap of which features require which.
The key is the feature name; the value is the list of features it
requires."
(let ((feature-requires (make-hash-table)))
(my/load-history--iter-load-history
(dolist (require-symbol requires)
(puthash provide-symbol
(cons require-symbol
(gethash provide-symbol feature-requires))
feature-requires)))
feature-requires))
(defun my/load-history-feature-dependencies (feature-name &optional narrow-use-package)
"Display the tree of features that FEATURE-NAME depends on.
If NARROW-USE-PACKAGE is non-nil, only show the features that are
managed by `use-package'."
(interactive (list (my/completing-read-features-or-packages)
(equal current-prefix-arg '(4))))
(let* ((feature-requires (my/load-history--get-feature-requires))
(tree (my/load-history--get-feature-tree feature-name feature-requires))
(buffer (generate-new-buffer (format "*feature-dependencies-%s*" feature-name))))
(when narrow-use-package
(setq tree (my/load-history--narrow-tree-by-use-package tree)))
(with-current-buffer buffer
(my/load-history--render-feature-tree-recur tree)
(my/load-history-tree-mode)
(goto-char (point-min)))
(switch-to-buffer buffer)))
(require 'dired)
(eval-when-compile
(require 'dired))
(defun my-function-with-dired ()
"Do something important with dired."
(interactive)
(require 'dired))