1 ;;; map.el --- Map manipulation functions -*- lexical-binding: t; -*-
3 ;; Copyright (C) 2015-2016 Free Software Foundation, Inc.
5 ;; Author: Nicolas Petton <nicolas@petton.fr>
6 ;; Keywords: convenience, map, hash-table, alist, array
10 ;; Maintainer: emacs-devel@gnu.org
12 ;; This file is part of GNU Emacs.
14 ;; GNU Emacs is free software: you can redistribute it and/or modify
15 ;; it under the terms of the GNU General Public License as published by
16 ;; the Free Software Foundation, either version 3 of the License, or
17 ;; (at your option) any later version.
19 ;; GNU Emacs is distributed in the hope that it will be useful,
20 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
21 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 ;; GNU General Public License for more details.
24 ;; You should have received a copy of the GNU General Public License
25 ;; along with this program. If not, see <http://www.gnu.org/licenses/>.
29 ;; map.el provides map-manipulation functions that work on alists,
30 ;; hash-table and arrays. All functions are prefixed with "map-".
32 ;; Functions taking a predicate or iterating over a map using a
33 ;; function take the function as their first argument. All other
34 ;; functions take the map as their first argument.
37 ;; - Add support for char-tables
38 ;; - Maybe add support for gv?
39 ;; - See if we can integrate text-properties
40 ;; - A macro similar to let-alist but working on any type of map could
47 (pcase-defmacro map (&rest args)
48 "Build a `pcase' pattern matching map elements.
50 ARGS is a list of elements to be matched in the map.
52 Each element of ARGS can be of the form (KEY PAT), in which case KEY is
53 evaluated and searched for in the map. The match fails if for any KEY
54 found in the map, the corresponding PAT doesn't match the value
55 associated to the KEY.
57 Each element can also be a SYMBOL, which is an abbreviation of a (KEY
58 PAT) tuple of the form (\\='SYMBOL SYMBOL).
60 Keys in ARGS not found in the map are ignored, and the match doesn't
63 ,@(map--make-pcase-bindings args)))
65 (defmacro map-let (keys map &rest body)
66 "Bind the variables in KEYS to the elements of MAP then evaluate BODY.
68 KEYS can be a list of symbols, in which case each element will be
69 bound to the looked up value in MAP.
71 KEYS can also be a list of (KEY VARNAME) pairs, in which case
72 KEY is an unquoted form.
74 MAP can be a list, hash-table or array."
75 (declare (indent 2) (debug t))
76 `(pcase-let ((,(map--make-pcase-patterns keys) ,map))
80 (defmacro map--dispatch (map-var &rest args)
81 "Evaluate one of the forms specified by ARGS based on the type of MAP.
83 The following keyword types are meaningful: `:list',
84 `:hash-table' and `:array'.
86 An error is thrown if MAP is neither a list, hash-table nor array.
88 Return RESULT if non-nil or the result of evaluation of the form."
89 (declare (debug t) (indent 1))
90 `(cond ((listp ,map-var) ,(plist-get args :list))
91 ((hash-table-p ,map-var) ,(plist-get args :hash-table))
92 ((arrayp ,map-var) ,(plist-get args :array))
93 (t (error "Unsupported map: %s" ,map-var)))))
95 (defun map-elt (map key &optional default)
96 "Lookup KEY in MAP and return its associated value.
97 If KEY is not found, return DEFAULT which defaults to nil.
99 If MAP is a list, `eql' is used to lookup KEY.
101 MAP can be a list, hash-table or array."
105 (gv-letplace (mgetter msetter) `(gv-delay-error ,map)
107 ;; Eval them once and for all in the right order.
108 ((key key) (default default))
109 `(if (listp ,mgetter)
110 ;; Special case the alist case, since it can't be handled by the
111 ;; map--put function.
112 ,(gv-get `(alist-get ,key (gv-synthetic-place
116 ,(funcall do `(map-elt ,mgetter ,key ,default)
117 (lambda (v) `(map--put ,mgetter ,key ,v)))))))))
119 :list (alist-get key map default)
120 :hash-table (gethash key map default)
121 :array (if (and (>= key 0) (< key (seq-length map)))
125 (defmacro map-put (map key value)
126 "Associate KEY with VALUE in MAP and return VALUE.
127 If KEY is already present in MAP, replace the associated value
130 MAP can be a list, hash-table or array."
131 `(setf (map-elt ,map ,key) ,value))
133 (defun map-delete (map key)
134 "Delete KEY from MAP and return MAP.
135 No error is signaled if KEY is not a key of MAP. If MAP is an
136 array, store nil at the index KEY.
138 MAP can be a list, hash-table or array."
140 :list (setf (alist-get key map nil t) nil)
141 :hash-table (remhash key map)
142 :array (and (>= key 0)
143 (<= key (seq-length map))
147 (defun map-nested-elt (map keys &optional default)
148 "Traverse MAP using KEYS and return the looked up value or DEFAULT if nil.
150 Map can be a nested map composed of alists, hash-tables and arrays."
151 (or (seq-reduce (lambda (acc key)
158 (defun map-keys (map)
159 "Return the list of keys in MAP.
161 MAP can be a list, hash-table or array."
162 (map-apply (lambda (key _) key) map))
164 (defun map-values (map)
165 "Return the list of values in MAP.
167 MAP can be a list, hash-table or array."
168 (map-apply (lambda (_ value) value) map))
170 (defun map-pairs (map)
171 "Return the elements of MAP as key/value association lists.
173 MAP can be a list, hash-table or array."
174 (map-apply #'cons map))
176 (defun map-length (map)
177 "Return the length of MAP.
179 MAP can be a list, hash-table or array."
180 (length (map-keys map)))
182 (defun map-copy (map)
183 "Return a copy of MAP.
185 MAP can be a list, hash-table or array."
188 :hash-table (copy-hash-table map)
189 :array (seq-copy map)))
191 (defun map-apply (function map)
192 "Apply FUNCTION to each element of MAP and return the result as a list.
193 FUNCTION is called with two arguments, the key and the value.
195 MAP can be a list, hash-table or array."
196 (funcall (map--dispatch map
197 :list #'map--apply-alist
198 :hash-table #'map--apply-hash-table
199 :array #'map--apply-array)
203 (defun map-keys-apply (function map)
204 "Return the result of applying FUNCTION to each key of MAP.
206 MAP can be a list, hash-table or array."
207 (map-apply (lambda (key _)
208 (funcall function key))
211 (defun map-values-apply (function map)
212 "Return the result of applying FUNCTION to each value of MAP.
214 MAP can be a list, hash-table or array."
215 (map-apply (lambda (_ val)
216 (funcall function val))
219 (defun map-filter (pred map)
220 "Return an alist of key/val pairs for which (PRED key val) is non-nil in MAP.
222 MAP can be a list, hash-table or array."
223 (delq nil (map-apply (lambda (key val)
224 (if (funcall pred key val)
229 (defun map-remove (pred map)
230 "Return an alist of the key/val pairs for which (PRED key val) is nil in MAP.
232 MAP can be a list, hash-table or array."
233 (map-filter (lambda (key val) (not (funcall pred key val)))
237 "Return non-nil if MAP is a map (list, hash-table or array)."
242 (defun map-empty-p (map)
243 "Return non-nil if MAP is empty.
245 MAP can be a list, hash-table or array."
248 :array (seq-empty-p map)
249 :hash-table (zerop (hash-table-count map))))
251 (defun map-contains-key (map key &optional testfn)
252 "Return non-nil if MAP contain KEY, nil otherwise.
253 Equality is defined by TESTFN if non-nil or by `equal' if nil.
255 MAP can be a list, hash-table or array."
256 (seq-contains (map-keys map) key testfn))
258 (defun map-some (pred map)
259 "Return a non-nil if (PRED key val) is non-nil for any key/value pair in MAP.
261 MAP can be a list, hash-table or array."
263 (map-apply (lambda (key value)
264 (let ((result (funcall pred key value)))
266 (throw 'map--break result))))
270 (defun map-every-p (pred map)
271 "Return non-nil if (PRED key val) is non-nil for all elements of the map MAP.
273 MAP can be a list, hash-table or array."
275 (map-apply (lambda (key value)
276 (or (funcall pred key value)
277 (throw 'map--break nil)))
281 (defun map-merge (type &rest maps)
282 "Merge into a map of type TYPE all the key/value pairs in MAPS.
284 MAP can be a list, hash-table or array."
287 (map-apply (lambda (key value)
288 (setf (map-elt result key) value))
290 (map-into result type)))
292 (defun map-merge-with (type function &rest maps)
293 "Merge into a map of type TYPE all the key/value pairs in MAPS.
294 When two maps contain the same key, call FUNCTION on the two
295 values and use the value returned by it.
296 MAP can be a list, hash-table or array."
299 (map-apply (lambda (key value)
300 (setf (map-elt result key)
301 (if (map-contains-key result key)
302 (funcall function (map-elt result key) value)
305 (map-into result type)))
307 (defun map-into (map type)
308 "Convert the map MAP into a map of type TYPE.
310 TYPE can be one of the following symbols: list or hash-table.
311 MAP can be a list, hash-table or array."
313 (`list (map-pairs map))
314 (`hash-table (map--into-hash-table map))
315 (_ (error "Not a map type name: %S" type))))
317 (defun map--put (map key v)
319 :list (let ((p (assoc key map)))
321 (error "No place to change the mapping for %S" key)))
322 :hash-table (puthash key v map)
323 :array (aset map key v)))
325 (defun map--apply-alist (function map)
326 "Private function used to apply FUNCTION over MAP, MAP being an alist."
327 (seq-map (lambda (pair)
333 (defun map--apply-hash-table (function map)
334 "Private function used to apply FUNCTION over MAP, MAP being a hash-table."
336 (maphash (lambda (key value)
337 (push (funcall function key value) result))
341 (defun map--apply-array (function map)
342 "Private function used to apply FUNCTION over MAP, MAP being an array."
344 (seq-map (lambda (elt)
346 (funcall function index elt)
347 (setq index (1+ index))))
350 (defun map--into-hash-table (map)
351 "Convert MAP into a hash-table."
352 (let ((ht (make-hash-table :size (map-length map)
354 (map-apply (lambda (key value)
355 (setf (map-elt ht key) value))
359 (defun map--make-pcase-bindings (args)
360 "Return a list of pcase bindings from ARGS to the elements of a map."
361 (seq-map (lambda (elt)
363 `(app (pcase--flip map-elt ,(car elt)) ,(cadr elt))
364 `(app (pcase--flip map-elt ',elt) ,elt)))
367 (defun map--make-pcase-patterns (args)
368 "Return a list of `(map ...)' pcase patterns built from ARGS."
370 (seq-map (lambda (elt)
371 (if (and (consp elt) (eq 'map (car elt)))
372 (map--make-pcase-patterns elt)