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https://github.com/radian-software/prescient.el

☄️ Simple but effective sorting and filtering for Emacs.
https://github.com/radian-software/prescient.el

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☄️ Simple but effective sorting and filtering for Emacs.

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README 

        
**prescient.el:** simple but effective sorting and filtering for

Emacs.



## Summary



`prescient.el` is a library which sorts and filters lists of

candidates, such as appear when you use a package like [Ivy] or

[Company]. Extension packages such as `ivy-prescient.el` and

`company-prescient.el` adapt the library for usage with various

frameworks.



`prescient.el` also provides a completion style (`prescient`) for

filtering candidates via Emacs's generic completion, such as in

[Icomplete], [Vertico], and [Corfu]. These last two have extension

packages to correctly set up filtering and sorting.



As compared to other packages which accomplish similar tasks,

including [IDO], [Ivy], [Helm], [Smex], [Flx], [Historian], and

[Company-Statistics], `prescient.el` aims to be simpler, more

predictable, and faster.



## Installation



`prescient.el` is available on MELPA as six separate packages (one

for the library, and the rest for integrating with other frameworks):



* [`prescient`](https://melpa.org/#/prescient)

* [`corfu-prescient`](https://melpa.org/#/corfu-prescient)

* [`company-prescient`](https://melpa.org/#/company-prescient)

* [`ivy-prescient`](https://melpa.org/#/ivy-prescient)

* [`selectrum-prescient`](https://melpa.org/#/selectrum-prescient)

* [`vertico-prescient`](https://melpa.org/#/vertico-prescient)



The easiest way to install these packages is using

[`straight.el`][straight.el]:



    (straight-use-package 'prescient)

    (straight-use-package 'corfu-prescient)

    (straight-use-package 'company-prescient)

    (straight-use-package 'ivy-prescient)

    (straight-use-package 'selectrum-prescient)

    (straight-use-package 'vertico-prescient)



However, you may install using any other package manager if you

prefer.



## Usage



`prescient.el` and the extension packages provide modes that configure

filtering and/or sorting in their respective framework. These modes

can have their own settings, such as ways to set up filtering but

not sorting, which are described in a following section.



* To cause Emacs to use the `prescient` completion style for

  filtering, add `prescient` to the user option `completion-styles`.



* To cause [Corfu] to use `prescient.el` sorting and filtering, enable

  `corfu-prescient-mode`.



* To cause [Company] to use `prescient.el` sorting, enable

  `company-prescient-mode`.



* To cause [Ivy] to use `prescient.el` sorting and filtering, enable

  `ivy-prescient-mode`.



* To cause [Selectrum] to use `prescient.el` sorting and filtering,

  enable `selectrum-prescient-mode`.



* To cause [Vertico] to use `prescient.el` sorting and filtering,

  enable `vertico-prescient-mode`.



* To cause your usage statistics to be saved between Emacs sessions,

  enable `prescient-persist-mode`.



Please note that **you must load Counsel before `ivy-prescient.el`**.

This is because loading Counsel results in a number of changes being

made to the user options of Ivy, which `ivy-prescient.el` must then

undo.



## Algorithm



`prescient.el` takes as input a list of candidates, and a query that

you type.



When filtering, the query is first split on spaces into subqueries

(two consecutive spaces match a literal space). Each subquery filters

the candidates according to the filter methods listed in

`prescient-filter-method`. By default, a subquery must match as either

a substring of the candidate, a regexp, or an initialism (e.g. `ffap`

matches `find-file-at-point`, and so does `fa`). A candidate must

match all subqueries to pass the filter and subqueries can be matched

in any order.



When sorting, the last few candidates you selected are displayed

first, followed by the most frequently selected ones, and then the

remaining candidates are sorted by length.



If you would like `prescient.el` to forget about a candidate, use the

command `prescient-forget`.



## Configuration and other features



* `prescient-history-length`: The number of recently selected

  candidates that are remembered and displayed at the top of the list.



* `prescient-frequency-decay`: `prescient.el` keeps a "frequency" for

  each selected candidate, which is incremented by one each time you

  select the candidate. To keep things tidy, frequencies are

  multiplied by this variable's value each time you select a new

  candidate, so they decrease over time.



* `prescient-frequency-threshold`: Once the frequency for an

  infrequently used command falls below the value of this variable,

  `prescient.el` forgets about it.



* `prescient-save-file`: Where to save statistics that are persisted

  between Emacs sessions when `prescient-persist-mode` is active. The

  default value follows the conventions of

  [`no-littering`][no-littering].



* `prescient-filter-method`: A list of algorithms to use for filtering

  candidates. The default is `literal`, `regexp`, and `initialism` as

  described above, but you can also use substring matching, initialism

  matching, regexp matching, fuzzy matching, prefix matching, anchored

  matching, literal-prefix matching, or any combination of those. See

  the docstring for full details.



* `prescient-filter-alist`: An alist of symbol-function pairs that

  associate a symbol in `prescient-filter-method` with a function that

  creates a regexp for matching a candidate. You can add to this alist

  to define your own custom filter methods, and use them by adding the

  appropriate symbol to `prescient-filter-method`.



* `prescient-sort-full-matches-first`: Whether `prescient.el` sorts

  candidates that are fully matched before candidates that are

  partially matched. This user option affects:

  - `corfu-prescient.el`

  - `company-prescient.el` for Company backends that used the

    `prescient` completion style for filtering

  - `selectrum-prescient.el`

  - `vertico-prescient.el`



* `prescient-sort-length-enable`: Whether to sort the candidates by

  length in addition to recency and frequency.



* `prescient-tiebreaker`: Function to use for breaking ties in recency

  instead of length.



* `prescient-use-char-folding`: Whether the `literal` and

  `literal-prefix` filter methods use character folding.



* `prescient-use-case-folding`: Whether filtering methods use case

  folding (in non-Emacs terms, whether they are case insensitive).

  This can be one of `nil`, `t`, or `smart` (the default). If `smart`,

  then case folding is disabled when upper-case characters are used.



* Quickly adjusting filtering: Commands are available to temporarily

  toggle filter methods on or off while you're completing candidates.

  These commands are similar in usage to Isearch's own toggling

  commands, except that multiple filtering methods can be active at

  the same time.



  For example, to toggle regexp filtering on or off (perhaps you're

  searching for a long/complex candidate), you can press `M-s r`. If

  you wish to use *only* regexp filtering, you can use `C-u M-s r` to

  unconditionally turn on regexp filtering and turn off all other

  methods. This toggling is a buffer-local effect, and does not change

  the default filtering behavior. For that, customize

  `prescient-filter-method`.



  `selectrum-prescient.el` and `vertico-prescient.el` will both bind

  commands to toggle filter methods in the current completion buffer.

  `corfu-prescient.el` will bind the commands while the Corfu pop-up

  is active. While the integration mode is enabled, `M-s` is bound to

  `prescient-toggle-map` in the completion buffer or Corfu pop-up, and

  is used as a prefix key to access the commands.



  | Key     | Command                           |

  |---------|-----------------------------------|

  | `M-s a` | `prescient-toggle-anchored`       |

  | `M-s f` | `prescient-toggle-fuzzy`          |

  | `M-s i` | `prescient-toggle-initialism`     |

  | `M-s l` | `prescient-toggle-literal`        |

  | `M-s p` | `prescient-toggle-prefix`         |

  | `M-s P` | `prescient-toggle-literal-prefix` |

  | `M-s r` | `prescient-toggle-regexp`         |

  | `M-s '` | `prescient-toggle-char-fold`      |

  | `M-s c` | `prescient-toggle-case-fold`      |



  When defining custom filter methods, you can create new bindings

  using `prescient-create-and-bind-toggle-command`, which takes an

  unquoted filter symbol and a string that can be used by `kbd`. For

  example,



  ```emacs-lisp

  (prescient-create-and-bind-toggle-command my-foo "M-f")

  ```



  will bind a command for toggling the `my-foo` filter to `M-s M-f`.



### Faces



`prescient.el` defines two faces: `prescient-primary-highlight` and

`prescient-secondary-highlight`. The primary highlight is used to

highlight matches in candidates. The secondary highlight is used for

important sections within each matched region. For example, the

`initialism` filter method highlights the entire match with

`prescient-primary-highlight` and each initial in the initialism with

`prescient-secondary-highlight`.



These faces are used by the `prescient` completion style (and so

completion frameworks using that style, such as Corfu and Vertico) and

Selectrum. `ivy-prescient.el` uses Ivy's faces.



The following example shows customizing these faces. I use the

[Zerodark](https://github.com/NicolasPetton/zerodark-theme) color

theme, which includes colors for Ivy, but not for Selectrum. I

inspected the theme source code to see what colors were being used for

Ivy, and copied them to be used for Selectrum as well:



```elisp

(require 'zerodark-theme)



(let ((class '((class color) (min-colors 89))))

  (custom-theme-set-faces

   'zerodark

   `(selectrum-current-candidate

     ((,class (:background "#48384c"

                           :weight bold

                           :foreground "#c678dd"))))

   `(prescient-primary-highlight

     ((,class (:foreground "#da8548"))))

   `(prescient-secondary-highlight

     ((,class (:foreground "#98be65"))))))



(enable-theme 'zerodark)

```



### For the completion style



The following user options are specific to using the `prescient`

completion style:



* `prescient-completion-highlight-matches`: Whether the completion

  style should highlight matches in the filtered candidates using the

  faces `prescient-primary-highlight` and `prescient-secondary-highlight`.



### For Corfu



`corfu-prescient.el` configures filtering locally in buffers in

which `corfu-mode` is active. To do this, it modifies the values of

`completion-styles`, `completion-category-overrides`, and

`completion-category-defaults`. Sorting is configured globally.



The following user options are specific to using `prescient.el` with

Corfu:



* `corfu-prescient-completion-styles`: What the value of

  `completion-styles` is changed to.



* `corfu-prescient-completion-category-overrides`: Overrides that

  should be included in `completion-category-overrides`.



* `corfu-prescient-enable-filtering`: If non-nil when

  `corfu-prescient-mode` is enabled, then

  * `M-s` is bound to `prescient-toggle-map` while the Corfu pop-up is

    active

  * `completion-styles` is changed to the value of

    `corfu-prescient-completion-styles`

  * `completion-category-overrides` is changed to include overrides in

    `corfu-prescient-completion-category-overrides`

  * `completion-category-defaults` is set to `nil`



* `corfu-prescient-enable-sorting`: If non-nil when

  `corfu-prescient-mode` is enabled, then `corfu-sort-function` is

   set to the function `prescient-completion-sort`.



* `corfu-prescient-override-sorting`: If non-nil when

  `corfu-prescient-mode` is enabled, then

  `corfu-sort-override-function` is set to the function

  `prescient-completion-sort` and `corfu-prescient-enable-sorting` is

  made non-nil.



### For Company



The following user options are specific to using `prescient.el`

sorting with Company:



* `company-prescient-sort-length-enable`: By default, the standard

  `prescient.el` sorting algorithm is used for all Company completions

  when `company-prescient-mode` is enabled. However, this algorithm is

  inappropriate in some situations. In particular, some Company

  backends return fuzzy-matched candidates with an intelligent sorting

  pre-applied. In this case, the fallback sorting by length that

  `prescient.el` does will just make a giant mess of things. By

  customizing this user option to nil for such Company backends (see

  [Radian][radian-sort-length-enable] for an example), you can avoid

  the problem. Then `prescient.el` will helpfully move recently and

  frequently used candidates to the top of the completions list, but

  otherwise leave candidate ordering alone.



### For Ivy



The following user options are specific to using `prescient.el` with

Ivy:



* `ivy-prescient-sort-commands`: By default, all commands have their

  candidates sorted. You can override this behavior by customizing

  `ivy-prescient-sort-commands`. See the docstring.



* `ivy-prescient-retain-classic-highlighting`: By default, the

  highlighting behavior of `ivy-prescient.el` is slightly different

  from Ivy's highlighting for `ivy--regex-ignore-order`. You can

  recover the original behavior by customizing this user option; see

  the docstring for more details.



* `ivy-prescient-enable-filtering`: If set to nil, then

  `ivy-prescient.el` does not apply `prescient.el` filtering to Ivy.

  See the Ivy documentation for information on how Ivy filters by

  default, and how to customize it manually.



* `ivy-prescient-enable-sorting`: If set to nil, then

  `ivy-prescient.el` does not apply `prescient.el` sorting to Ivy. See

  the Ivy documentation for information on how Ivy sorts by default,

  and how to customize it manually.



### For Selectrum



The following user options are specific to using `prescient.el` with

Selectrum:



* `selectrum-prescient-enable-filtering`: If set to nil, then

  `selectrum-prescient.el` does not change filtering of Selectrum. See

  the Selectrum documentation for information on how Selectrum

  configures filtering by default, and how to customize it manually.



  Additionally, when set, the matched part of each candidate is

  highlighted using the faces described above.



* `selectrum-prescient-enable-sorting`: If set to nil, then

  `selectrum-prescient.el` does not change sorting of Selectrum. See

  the Selectrum documentation for information on how Selectrum

  configures sorting by default, and how to customize it manually.



### For Vertico



`vertico-prescient.el` configures filtering locally in the Vertico

buffer. To do this, it modifies the values of `completion-styles`,

`completion-category-overrides`, and `completion-category-defaults`.

Sorting is configured globally.



The following user options are specific to using `prescient.el` with

Vertico:



* `vertico-prescient-completion-styles`: What the value of

  `completion-styles` is changed to.



* `vertico-prescient-completion-category-overrides`: Overrides that

  should be included in `completion-category-overrides`.



* `vertico-prescient-enable-filtering`: If non-nil when

  `vertico-prescient-mode` is enabled, then

  * `M-s` is bound to `prescient-toggle-map`

  * `completion-styles` is changed to the value of

    `vertico-prescient-completion-styles`

  * `completion-category-overrides` is changed to include overrides in

    `vertico-prescient-completion-category-overrides`

  * `completion-category-defaults` is set to `nil`



* `vertico-prescient-enable-sorting`: If non-nil when

  `vertico-prescient-mode` is enabled, then `vertico-sort-function` is

   set to the function `prescient-completion-sort`.



* `vertico-prescient-override-sorting`: If non-nil when

  `vertico-prescient-mode` is enabled, then

  `vertico-sort-override-function` is set to the function

  `prescient-completion-sort` and `vertico-prescient-enable-sorting` is

  made non-nil.



## Contributor guide



Please see [the contributor guide for my

projects](https://github.com/raxod502/contributor-guide).



[corfu]: https://github.com/minad/corfu

[company]: https://github.com/company-mode/company-mode

[company-statistics]: https://github.com/company-mode/company-statistics

[counsel]: https://github.com/abo-abo/swiper#counsel

[flx]: https://github.com/lewang/flx

[helm]: https://github.com/emacs-helm/helm

[historian]: https://github.com/PythonNut/historian.el

[icomplete]: https://www.gnu.org/software/emacs/manual/html_node/emacs/Icomplete.html

[ido]: https://www.gnu.org/software/emacs/manual/ido.html

[ivy]: https://github.com/abo-abo/swiper#ivy

[ivy-release]: https://github.com/abo-abo/swiper/issues/1664

[no-littering]: https://github.com/emacscollective/no-littering

[radian-sort-length-enable]: https://github.com/raxod502/radian/blob/06f2a30258deacb719a195221747ce1d528fc2fe/emacs/radian.el#L2513-L2532

[selectrum]: https://github.com/raxod502/selectrum

[smex]: https://github.com/nonsequitur/smex

[straight.el]: https://github.com/raxod502/straight.el

[vertico]: https://github.com/minad/vertico