Re: [PATCH] extend map-into

[Andrea Corallo]

Stefan Monnier <address@hidden> writes:

>> attached.
>
> Thanks, installed into `master` with minor tweaks (e.g. the NEWS entry
> was misplaced, and I changed the defsubst into a defun because the
> function itself contains a loop so the overhead of the function call is
> unlikely to be significant in proportion).
>
>
>         Stefan

Cool thanks!

Bests
  Andrea

>
>> From 7a1b42b1b58f7b0ee20ef24e9e73bce045a1987b Mon Sep 17 00:00:00 2001
>> From: Andrea Corallo <address@hidden>
>> Date: Sun, 6 Oct 2019 22:43:11 +0200
>> Subject: [PATCH] Extend 'map-into' for better control on hash table creation.
>>
>> ---
>>  etc/NEWS                          |  4 ++++
>>  lisp/emacs-lisp/map.el            | 29 +++++++++++++++++++++--------
>>  test/lisp/emacs-lisp/map-tests.el |  5 ++++-
>>  3 files changed, 29 insertions(+), 9 deletions(-)
>>
>> diff --git a/etc/NEWS b/etc/NEWS
>> index c8cc753..5942a32 100644
>> --- a/etc/NEWS
>> +++ b/etc/NEWS
>> @@ -24,6 +24,10 @@ applies, and please also update docstrings as needed.
>>  
>>  * Installation Changes in Emacs 27.1
>>  
>> +** Extend function 'map-into'.
>> +Add a 'map-into' method to have hash table creation parameters
>> +tweak-able.
>> +
>>  ** Emacs now uses GMP, the GNU Multiple Precision library.
>>  By default, if 'configure' does not find a suitable libgmp, it
>>  arranges for the included mini-gmp library to be built and used.
>> diff --git a/lisp/emacs-lisp/map.el b/lisp/emacs-lisp/map.el
>> index 54e802e..dfc1500 100644
>> --- a/lisp/emacs-lisp/map.el
>> +++ b/lisp/emacs-lisp/map.el
>> @@ -338,7 +338,8 @@ map-every-p
>>      t))
>>  
>>  (defun map-merge (type &rest maps)
>> -  "Merge into a map of type TYPE all the key/value pairs in MAPS."
>> +  "Merge into a map of type TYPE all the key/value pairs in MAPS.
>> +See `map-into' for all supported values of TYPE."
>>    (let ((result (map-into (pop maps) type)))
>>      (while maps
>>        ;; FIXME: When `type' is `list', we get an O(N^2) behavior.
>> @@ -354,7 +355,8 @@ map-merge-with
>>    "Merge into a map of type TYPE all the key/value pairs in MAPS.
>>  When two maps contain the same key (`eql'), call FUNCTION on the two
>>  values and use the value returned by it.
>> -MAP can be a list, hash-table or array."
>> +MAP can be a list, hash-table or array.
>> +See `map-into' for all supported values of TYPE."
>>    (let ((result (map-into (pop maps) type))
>>          (not-found (cons nil nil)))
>>      (while maps
>> @@ -458,17 +460,28 @@ map-do
>>                       (funcall function index elt))
>>                     array))
>>  
>> -(cl-defmethod map-into (map (_type (eql hash-table)))
>> -  "Convert MAP into a hash-table."
>> -  ;; FIXME: Just knowing we want a hash-table is insufficient, since that
>> -  ;; doesn't tell us the test function to use with it!
>> -  (let ((ht (make-hash-table :size (map-length map)
>> -                             :test 'equal)))
>> +(defsubst map--into-hash (map keyword-args)
>> +  "Convert MAP into a hash-table.
>> +KEYWORD-ARGS are forwarded to `make-hash-table'."
>> +  (let ((ht (apply #'make-hash-table keyword-args)))
>>      (map-apply (lambda (key value)
>>                   (setf (map-elt ht key) value))
>>                 map)
>>      ht))
>>  
>> +(cl-defmethod map-into (map (_type (eql hash-table)))
>> +  "Convert MAP into a hash-table."
>> +  (map--into-hash map (list :size (map-length map) :test 'equal)))
>> +
>> +(cl-defmethod map-into (map (args (head hash-table)))
>> +  "Convert MAP into a hash-table.
>> +ARGS is a list where the car is 'hash-table' and the cdr are the 
>> keyword-args
>> + forwarded to `make-hash-table'.
>> +
>> +Example:
>> +    (map-into '((1 . 3)) '(hash-table :test eql))"
>> +  (map--into-hash map (cdr args)))
>> +
>>  (defun map--make-pcase-bindings (args)
>>    "Return a list of pcase bindings from ARGS to the elements of a map."
>>    (seq-map (lambda (elt)
>> diff --git a/test/lisp/emacs-lisp/map-tests.el 
>> b/test/lisp/emacs-lisp/map-tests.el
>> index a54af80..9f61511 100644
>> --- a/test/lisp/emacs-lisp/map-tests.el
>> +++ b/test/lisp/emacs-lisp/map-tests.el
>> @@ -340,7 +340,8 @@ test-map-every-p
>>  
>>  (ert-deftest test-map-into ()
>>    (let* ((alist '((a . 1) (b . 2)))
>> -         (ht (map-into alist 'hash-table)))
>> +         (ht (map-into alist 'hash-table))
>> +         (ht2 (map-into alist '(hash-table :test eq))))
>>      (should (hash-table-p ht))
>>      (should (equal (map-into (map-into alist 'hash-table) 'list)
>>                     alist))
>> @@ -349,6 +350,8 @@ test-map-into
>>                     (map-keys ht)))
>>      (should (equal (map-values (map-into (map-into ht 'list) 'hash-table))
>>                     (map-values ht)))
>> +    (should (equal (map-into ht 'alist) (map-into ht2 'alist)))
>> +    (should (eq (hash-table-test ht2) 'eq))
>>      (should (null (map-into nil 'list)))
>>      (should (map-empty-p (map-into nil 'hash-table)))
>>      (should-error (map-into [1 2 3] 'string))))
>
>

-- 
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