diff options
Diffstat (limited to 'lisp/emacs-lisp/map.el')
| -rw-r--r-- | lisp/emacs-lisp/map.el | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/lisp/emacs-lisp/map.el b/lisp/emacs-lisp/map.el index 7a48ba47434..b46c74343c0 100644 --- a/lisp/emacs-lisp/map.el +++ b/lisp/emacs-lisp/map.el @@ -8,6 +8,9 @@ ;; Version: 3.3.1 ;; Package-Requires: ((emacs "26")) +;; This is a GNU ELPA :core package. Avoid functionality that is not +;; compatible with the version of Emacs recorded above. + ;; This file is part of GNU Emacs. ;; GNU Emacs is free software: you can redistribute it and/or modify @@ -50,18 +53,20 @@ ARGS is a list of elements to be matched in the map. -Each element of ARGS can be of the form (KEY PAT), in which case KEY is -evaluated and searched for in the map. The match fails if for any KEY -found in the map, the corresponding PAT doesn't match the value -associated with the KEY. +Each element of ARGS can be of the form (KEY PAT [DEFAULT]), +which looks up KEY in the map and matches the associated value +against `pcase' pattern PAT. DEFAULT specifies the fallback +value to use when KEY is not present in the map. If omitted, it +defaults to nil. Both KEY and DEFAULT are evaluated. Each element can also be a SYMBOL, which is an abbreviation of a (KEY PAT) tuple of the form (\\='SYMBOL SYMBOL). When SYMBOL is a keyword, it is an abbreviation of the form (:SYMBOL SYMBOL), useful for binding plist values. -Keys in ARGS not found in the map are ignored, and the match doesn't -fail." +An element of ARGS fails to match if PAT does not match the +associated value or the default value. The overall pattern fails +to match if any element of ARGS fails to match." `(and (pred mapp) ,@(map--make-pcase-bindings args))) @@ -71,12 +76,13 @@ fail." KEYS can be a list of symbols, in which case each element will be bound to the looked up value in MAP. -KEYS can also be a list of (KEY VARNAME) pairs, in which case -KEY is an unquoted form. +KEYS can also be a list of (KEY VARNAME [DEFAULT]) sublists, in +which case KEY and DEFAULT are unquoted forms. MAP can be an alist, plist, hash-table, or array." (declare (indent 2) - (debug ((&rest &or symbolp ([form symbolp])) form body))) + (debug ((&rest &or symbolp ([form symbolp &optional form])) + form body))) `(pcase-let ((,(map--make-pcase-patterns keys) ,map)) ,@body)) @@ -595,11 +601,21 @@ Example: (map-into \\='((1 . 3)) \\='(hash-table :test eql))" (map--into-hash map (cdr type))) +(defmacro map--pcase-map-elt (key default map) + "A macro to make MAP the last argument to `map-elt'. + +This allows using default values for `map-elt', which can't be +done using `pcase--flip'. + +KEY is the key sought in the map. DEFAULT is the default value." + `(map-elt ,map ,key ,default)) + (defun map--make-pcase-bindings (args) "Return a list of pcase bindings from ARGS to the elements of a map." (mapcar (lambda (elt) (cond ((consp elt) - `(app (pcase--flip map-elt ,(car elt)) ,(cadr elt))) + `(app (map--pcase-map-elt ,(car elt) ,(caddr elt)) + ,(cadr elt))) ((keywordp elt) (let ((var (intern (substring (symbol-name elt) 1)))) `(app (pcase--flip map-elt ,elt) ,var))) |