doomemacs/modules/tools/lookup/README.org

#+title:    :tools lookup
#+subtitle: Navigate your labyrinthine code and docs
#+created:  January 04, 2018
#+since:    2.0.9

* Description :unfold:
This module adds code navigation and documentation lookup tools to help you
quickly look up definitions, references, documentation, dictionary definitions
or synonyms.

- Jump-to-definition and find-references implementations that just work.
- Powerful xref integration for languages that support it.
- Search online providers like [[https://devdocs.io][devdocs.io]], [[https://stackoverflow.com][stackoverflow]], [[https://google.com][google]], [[https://duckduckgo.com][duckduckgo]], or
  [[https://youtube.com][youtube]] (duckduckgo and google have live suggestions).
- Integration with [[https://github.com/Kapeli/feeds][Dash.app docsets]].
- Support for online (and offline) dictionaries and thesauruses.

** Maintainers
- [[doom-user:][@hlissner]]

[[doom-contrib-maintainer:][Become a maintainer?]]

** Module flags
- +dictionary ::
  Enable word definition and thesaurus lookup functionality.
- +docsets ::
  Enable integration with Dash.app docsets.
- +offline ::
  Install and prefer offline dictionary/thesaurus (with [[doom-module:+dictionary]]).

** Packages
- [[doom-package:dumb-jump]]
- [[doom-package:helm-xref]] if [[doom-module::completion helm]]
- [[doom-package:ivy-xref]] if [[doom-module::completion ivy]]
- [[doom-package:request]]
- if [[doom-module:+docsets]]
  - [[doom-package:dash-docs]]
  - [[doom-package:counsel-dash]] if [[doom-module::completion ivy]]
  - [[doom-package:helm-dash]] if [[doom-module::completion helm]]
- if [[doom-module:+dictionary]]
  - if macOS
    - [[doom-package:osx-dictionary]]
  - else
    - [[doom-package:define-word]]
    - [[doom-package:powerthesaurus]]
    - if [[doom-module:+offline]]
      - [[doom-package:wordnut]]
      - [[doom-package:synosaurus]]

** Hacks
/No hacks documented for this module./

** TODO Changelog
# This section will be machine generated. Don't edit it by hand.
/This module does not have a changelog yet./

* Installation
[[id:01cffea4-3329-45e2-a892-95a384ab2338][Enable this module in your ~doom!~ block.]]

This module has several optional dependencies:

- ~ripgrep~ as a last-resort fallback for jump-to-definition/find-references.
- ~sqlite3~ for Dash docset support (if you have [[doom-module:+docsets]] enabled)
- ~wordnet~ for offline dictionary and thesaurus support (if you have
  [[doom-module:+dictionary]] and [[doom-module:+offline]] enabled).

** MacOS
#+begin_src sh
brew install ripgrep wordnet

# An older version of sqlite is included in MacOS. If it causes you problems (and
# folks have reported it will), install it through homebrew:
brew install sqlite
# Note that it's keg-only, meaning it isn't symlinked to /usr/local/bin. You'll
# have to add it to PATH yourself (or symlink it into your PATH somewhere). e.g.
export PATH="/usr/local/opt/sqlite/bin:$PATH"
#+end_src

** Arch Linux
#+begin_src sh
sudo pacman -S sqlite ripgrep
yay -S wordnet-cli
#+end_src

** NixOS
#+begin_src nix
environment.systemPackages = with pkgs; [
  ripgrep
  sqlite
  wordnet
];
#+end_src

* Usage
** Jump to definition
Use ~+lookup/definition~ (bound to [[kbd:][gd]] in normal mode) to jump to the definition
of the symbol at point.

This module provides a goto-definition implementation that will try the
following sources before giving up:

1. Whatever ~:definition~ function is registered for the current buffer with the
   ~:lookup~ setting (see "Configuration" section).
2. Any available xref backends.
3. [[doom-package:dumb-jump]] (a text search with aides to reduce false positives).
3. An ordinary project-wide text search with =ripgrep=.
5. If ~evil-mode~ is active, use ~evil-goto-definition~, which preforms a simple
   text search within the current buffer.

If there are multiple results, you will be prompted to select one.

** Find references
Use ~+lookup/references~ (bound to [[kbd:][gD]] in normal mode) to see a list of
references for the symbol at point from throughout your project.

Like ~+lookup/definition~, this tries a number of sources before giving up. It
will try:

1. Whatever ~:references~ function is registered for the current buffer with the
   ~:lookup~ setting (see [[*Configuration][Configuration]]).
2. Any available [[doom-package:xref]] backends.
3. An ordinary project-wide text search with ripgrep.

If there are multiple results, you will be prompted to select one.

** Look up documentation
~+lookup/documentation~ (bound to [[kbd:][K]] in normal mode) will open documentation for
the symbol at point.

Depending on your configuration, this will try a list of sources:

1. Whatever ~:documentation~ function is registered for the current buffer with
   the ~:lookup~ setting (see "Configuration" section).
2. Any Dash.app docsets, if any are installed for the current major mode.
3. devdocs.io, if it has a docset for the current mode.
4. An online search; using the last engine used (it will prompt you the first
   time, or if ~current-prefix-arg~ is non-nil).

** Search a specific documentation backend
You can perform a documentation lookup on any backends directly:

+ Dash Docsets: ~+lookup/in-docsets~, or ~:dash QUERY~ for evil users.
+ Online (generic): ~+lookup/online~ or ~+lookup/online-select~ (bound to [[kbd:][SPC /
  o]]), or ~:lo[okup] QUERY~ for evil users.

** Dash.app Docset integration
You can install dash docsets with ~M-x dash-docs-install-docset~ and search
them offline with ~M-x +lookup/in-docsets~, or with ~+lookup/documentation~ in
modes that don't have a specialized :documentation lookup handler.

* Configuration
** Associating lookup handlers with major modes
~set-lookup-handlers! MODES &key DEFINITION REFERENCES DOCUMENTATION FILE
XREF-BACKEND ASYNC~

Use ~set-lookup-handlers!~ to register lookup targets for MODES (a major or
minor mode symbol or list thereof). PLIST accepts the following optional
properties:

- ~:definition FN~ ::
  Run when jumping to a symbol's definition. Used by ~+lookup/definition~.
- ~:references FN~ ::
  Run when looking for usage references of a symbol in the current project. Used
  by ~+lookup/references~.
- ~:documentation FN~ ::
  Run when looking up documentation for a symbol. Used by
  ~+lookup/documentation~.
- ~:file FN~ ::
  Run when looking up the file for a symbol/string. Typically a file path. Used
  by ~+lookup/file~.
- ~:xref-backend FN~ ::
  Defines an [[doom-package:xref]] backend, which implicitly provides ~:definition~ and
  ~:references~ handlers. If you specify them anyway, they will take precedence
  over the xref backend, however.

E.g.
#+begin_src emacs-lisp
;; For python-mode, anaconda-mode offers a backend for all three lookup
;; functions. We can register them like so:
(set-lookup-handlers! 'python-mode
  :definition #'anaconda-mode-find-definitions
  :references #'anaconda-mode-find-references
  :documentation #'anaconda-mode-show-doc)

;; If a language or plugin provides a custom xref backend available for it, use
;; that instead. It will provide the best jump-to-definition and find-references
;; experience. You can specify custom xref backends with:
(set-lookup-handlers! 'js2-mode :xref-backend #'xref-js2-xref-backend)
;; NOTE: xref doesn't provide a :documentation backend.
#+end_src

** Associating Dash docsets with major modes
~set-docsets! MODES &rest DOCSETS...~

Use ~set-docsets!~ to register DOCSETS (one string or list of strings) for MODES
(one major mode symbol or a list of them). It is used by ~+lookup/in-docsets~
and ~+lookup/documentation~.

E.g.
#+begin_src emacs-lisp
(set-docsets! 'js2-mode "JavaScript" "JQuery")
;; Add docsets to minor modes by starting DOCSETS with :add
(set-docsets! 'rjsx-mode :add "React")
;; Or remove docsets from minor modes
(set-docsets! 'nodejs-mode :remove "JQuery")
#+end_src

This determines what docsets to implicitly search for when you use
~+lookup/documentation~ in a mode with no ~:documentation~ handler. Those
docsets must be installed with ~dash-docs-install-docset~.

** Open in eww instead of browser
~+lookup/online~ opens the search results with in ~+lookup-open-url-fn~
(default: ~#'browse-url~). Here is how to change this to EWW (so it opens inside
Emacs):
#+begin_src emacs-lisp
(setq +lookup-open-url-fn #'eww)
#+end_src

#+begin_quote
 󰐃 ~+lookup/in-docsets~ consults ~dash-docs-browser-func~ instead, which is
    already set to ~#'eww~ by default.
#+end_quote

** Open in Xwidget WebKit instead of browser
To open results from ~+lookup/online~ or ~+lookup/in-docsets~ in Xwidget WebKit
instead of your system browser, set ~+lookup-open-url-fn~ and/or
~dash-docs-browser-func~ to ~+lookup-xwidget-webkit-open-url-fn~ (needs Emacs
with Xwidgets support):
#+begin_src emacs-lisp
(setq +lookup-open-url-fn #'+lookup-xwidget-webkit-open-url-fn)
(with-eval-after-load 'dash-docs
  (setq dash-docs-browser-func #'+lookup-xwidget-webkit-open-url-fn))
#+end_src

* Troubleshooting
/There are no known problems with this module./ [[doom-report:][Report one?]]

* Frequently asked questions
/This module has no FAQs yet./ [[doom-suggest-faq:][Ask one?]]

* TODO Appendix
#+begin_quote
 󱌣 /This module's appendix is incomplete./ [[doom-contrib-module:][Write more?]]
#+end_quote

** Commands
- ~+lookup/definition~
- ~+lookup/references~
- ~+lookup/documentation~
- ~+lookup/online~
- ~+lookup/online-select~
- ~+lookup/in-devdocs~
- ~+lookup/in-docsets~