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Diffstat (limited to 'configs/shared/emacs/.emacs.d/elpa/memoize-20180614.1230/memoize.el')
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diff --git a/configs/shared/emacs/.emacs.d/elpa/memoize-20180614.1230/memoize.el b/configs/shared/emacs/.emacs.d/elpa/memoize-20180614.1230/memoize.el new file mode 100644 index 0000000000..d45c5e4029 --- /dev/null +++ b/configs/shared/emacs/.emacs.d/elpa/memoize-20180614.1230/memoize.el @@ -0,0 +1,189 @@ +;;; memoize.el --- Memoization functions -*- lexical-binding: t; -*- + +;; This is free and unencumbered software released into the public domain. + +;; Author: Christopher Wellons <mosquitopsu@gmail.com> +;; URL: https://github.com/skeeto/emacs-memoize +;; Package-Version: 20180614.1230 +;; Version: 1.1 + +;;; Commentary: + +;; `memoize' accepts a symbol or a function. When given a symbol, the +;; symbol's function definition is memoized and installed overtop of +;; the original function definition. When given a function, it returns +;; a memoized version of that function. + +;; (memoize 'my-expensive-function) + +;; `defmemoize' defines a memoized function directly, behaving just +;; like `defun'. + +;; (defmemoize my-expensive-function (x) +;; (if (zerop n) +;; 1 +;; (* n (my-expensive-function (1- n))))) + +;; Memoizing an interactive function will render that function +;; non-interactive. It would be easy to fix this problem when it comes +;; to non-byte-compiled functions, but recovering the interactive +;; definition from a byte-compiled function is more complex than I +;; care to deal with. Besides, interactive functions are always used +;; for their side effects anyway. + +;; There's no way to memoize nil returns, but why would your expensive +;; functions do all that work just to return nil? :-) + +;; Memoization takes up memory, which should be freed at some point. +;; Because of this, all memoization has a timeout from when the last +;; access was. The default timeout is set by +;; `memoize-default-timeout'. It can be overriden by using the +;; `memoize' function, but the `defmemoize' macro will always just use +;; the default timeout. + +;; If you wait to byte-compile the function until *after* it is +;; memoized then the function and memoization wrapper both get +;; compiled at once, so there's no special reason to do them +;; separately. But there really isn't much advantage to compiling the +;; memoization wrapper anyway. + +;;; Code: + +(require 'cl-lib) + +(defvar memoize-default-timeout "2 hours" + "The amount of time after which to remove a memoization. +This represents the time after last use of the memoization after +which the value is expired. Setting this to nil means to never +expire, which will cause a memory leak, but may be acceptable for +very careful uses.") + +(defun memoize (func &optional timeout) + "Memoize FUNC: a closure, lambda, or symbol. + +If argument is a symbol then install the memoized function over +the original function. The TIMEOUT value, a timeout string as +used by `run-at-time' will determine when the value expires, and +will apply after the last access (unless another access +happens)." + (cl-typecase func + (symbol + (when (get func :memoize-original-function) + (user-error "%s is already memoized" func)) + (put func :memoize-original-documentation (documentation func)) + (put func 'function-documentation + (concat (documentation func) " (memoized)")) + (put func :memoize-original-function (symbol-function func)) + (fset func (memoize--wrap (symbol-function func) timeout)) + func) + (function (memoize--wrap func timeout)))) + +(defun memoize-restore (func) + "Restore the original, non-memoized definition of FUNC. +FUNC should be a symbol which has been memoized with `memoize'." + (unless (get func :memoize-original-function) + (user-error "%s is not memoized" func)) + (fset func (get func :memoize-original-function)) + (put func :memoize-original-function nil) + (put func 'function-documentation + (get func :memoize-original-documentation)) + (put func :memoize-original-documentation nil)) + +(defun memoize--wrap (func timeout) + "Return the memoized version of FUNC. +TIMEOUT specifies how long the values last from last access. A +nil timeout will cause the values to never expire, which will +cause a memory leak as memoize is use, so use the nil value with +care." + (let ((table (make-hash-table :test 'equal)) + (timeouts (make-hash-table :test 'equal))) + (lambda (&rest args) + (let ((value (gethash args table))) + (unwind-protect + (or value (puthash args (apply func args) table)) + (let ((existing-timer (gethash args timeouts)) + (timeout-to-use (or timeout memoize-default-timeout))) + (when existing-timer + (cancel-timer existing-timer)) + (when timeout-to-use + (puthash args + (run-at-time timeout-to-use nil + (lambda () + (remhash args table))) timeouts)))))))) + +(defmacro defmemoize (name arglist &rest body) + "Create a memoize'd function. NAME, ARGLIST, DOCSTRING and BODY +have the same meaning as in `defun'." + (declare (indent defun)) + `(progn + (defun ,name ,arglist + ,@body) + (memoize (quote ,name)))) + +(defun memoize-by-buffer-contents (func) + "Memoize the given function by buffer contents. +If argument is a symbol then install the memoized function over +the original function." + (cl-typecase func + (symbol + (put func 'function-documentation + (concat (documentation func) " (memoized by buffer contents)")) + (fset func (memoize-by-buffer-contents--wrap (symbol-function func))) + func) + (function (memoize-by-buffer-contents--wrap func)))) + +(defun memoize-by-buffer-contents--wrap (func) + "Return the memoization based on the buffer contents of FUNC. + +This form of memoization will be based off the current buffer +contents. A different memoization is stored for all buffer +contents, although old contents and no-longer-existant buffers +will get garbage collected." + ;; We need 3 tables here to properly garbage collect. First is the + ;; table for the memoization itself, `memoization-table'. It holds a + ;; cons of the content hash and the function arguments. + ;; + ;; Buffer contents change often, though, so we want these entries to + ;; be automatically garbage collected when the buffer changes or the + ;; buffer goes away. To keep the entries around, we need to tie the + ;; content hash to the buffer, so that the content hash string + ;; doesn't go away until the buffer does. We do that with the + ;; `buffer-to-contents-table'. + ;; + ;; But even if the buffer content does change, we need to expire the + ;; memoization entries for that particular buffer content. So we + ;; have a `contents-to-memoization-table' that we use to tie the + ;; content hash to the memoization conses used as keys in the + ;; `memoization-table'. + ;; + ;; If a buffer's value changes, we make sure the next time we put a + ;; new value at the `buffer-to-contents-table', which causes the + ;; hash string to disappear. This causes the hash-string to + ;; disappear from the `contents-to-memoization-table', which causes + ;; the memoizations based on that content string to disappear from + ;; the `memoization-table'. + (let ((memoization-table (make-hash-table :test 'equal :weakness 'key)) + (buffer-to-contents-table (make-hash-table :weakness 'key)) + (contents-to-memoization-table (make-hash-table :weakness 'key))) + (lambda (&rest args) + (let* ((bufhash (secure-hash 'md5 (buffer-string))) + (memokey (cons bufhash args)) + (value (gethash memokey memoization-table))) + (or value + (progn + (puthash (current-buffer) bufhash buffer-to-contents-table) + (puthash bufhash memokey contents-to-memoization-table) + (puthash memokey (apply func args) memoization-table))))))) + +(defmacro defmemoize-by-buffer-contents (name arglist &rest body) + "Create a memoize'd-by-buffer-contents function. NAME, ARGLIST, +DOCSTRING and BODY have the same meaning as in `defun'." + (declare (indent defun)) + `(progn + (defun ,name ,arglist + ,@body) + (memoize-by-buffer-contents (quote ,name)))) + +(provide 'memoize) + +;;; memoize.el ends here |