305 lines
8.8 KiB
EmacsLisp
305 lines
8.8 KiB
EmacsLisp
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;;; ht.el --- The missing hash table library for Emacs
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;; Copyright (C) 2013 Wilfred Hughes
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;; Author: Wilfred Hughes <me@wilfred.me.uk>
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;; Version: 2.2
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;; Package-Version: 20160806.1753
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;; Keywords: hash table, hash map, hash
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;; Package-Requires: ((dash "2.12.0"))
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;; This program is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with this program. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; The missing hash table library for Emacs.
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;;
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;; See documentation at https://github.com/Wilfred/ht.el
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;;; Code:
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(require 'dash)
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(defmacro ht (&rest pairs)
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"Create a hash table with the key-value pairs given.
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Keys are compared with `equal'.
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\(fn (KEY-1 VALUE-1) (KEY-2 VALUE-2) ...)"
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(let* ((table-symbol (make-symbol "ht-temp"))
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(assignments
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(mapcar
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(lambda (pair) `(ht-set! ,table-symbol ,@pair))
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pairs)))
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`(let ((,table-symbol (ht-create)))
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,@assignments
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,table-symbol)))
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(defun ht-create (&optional test)
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"Create an empty hash table.
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TEST indicates the function used to compare the hash
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keys. Default is `equal'. It can be `eq', `eql', `equal' or a
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user-supplied test created via `define-hash-table-test'."
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(make-hash-table :test (or test 'equal)))
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(defun ht<-alist (alist &optional test)
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"Create a hash table with initial values according to ALIST.
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TEST indicates the function used to compare the hash
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keys. Default is `equal'. It can be `eq', `eql', `equal' or a
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user-supplied test created via `define-hash-table-test'."
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(let ((h (ht-create test)))
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;; the first key-value pair in an alist gets precedence, so we
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;; start from the end of the list:
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(dolist (pair (reverse alist) h)
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(let ((key (car pair))
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(value (cdr pair)))
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(ht-set! h key value)))))
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(defalias 'ht-from-alist 'ht<-alist)
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;; based on the excellent -partition from dash.el, but we aim to be self-contained
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(defun ht/group-pairs (list)
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"Return a new list with the items in LIST grouped into pairs.
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Errors if LIST doesn't contain an even number of elements."
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(let ((result)
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(sublist)
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(len 0))
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(while list
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;; take the head of LIST and push onto SUBLIST
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(setq sublist (cons (car list) sublist))
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(setq list (cdr list))
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(setq len (1+ len))
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(when (= len 2)
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;; push this two-item list onto RESULT
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(setq result (cons (nreverse sublist) result))
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(setq sublist nil)
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(setq len 0)))
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(when sublist (error "Expected an even number of elements"))
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(nreverse result)))
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(defun ht<-plist (plist &optional test)
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"Create a hash table with initial values according to PLIST.
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TEST indicates the function used to compare the hash
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keys. Default is `equal'. It can be `eq', `eql', `equal' or a
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user-supplied test created via `define-hash-table-test'."
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(let ((h (ht-create test)))
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(dolist (pair (ht/group-pairs plist) h)
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(let ((key (car pair))
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(value (cadr pair)))
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(ht-set! h key value)))))
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(defalias 'ht-from-plist 'ht<-plist)
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(defun ht-get (table key &optional default)
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"Look up KEY in TABLE, and return the matching value.
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If KEY isn't present, return DEFAULT (nil if not specified)."
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(gethash key table default))
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(defun ht-set! (table key value)
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"Associate KEY in TABLE with VALUE."
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(puthash key value table)
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nil)
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(defalias 'ht-set 'ht-set!)
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(defun ht-update! (table from-table)
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"Update TABLE according to every key-value pair in FROM-TABLE."
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(maphash
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(lambda (key value) (puthash key value table))
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from-table)
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nil)
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(defalias 'ht-update 'ht-update!)
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(defun ht-merge (&rest tables)
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"Crete a new tables that includes all the key-value pairs from TABLES.
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If multiple have tables have the same key, the value in the last
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table is used."
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(let ((merged (ht-create)))
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(mapc (lambda (table) (ht-update! merged table)) tables)
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merged))
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(defun ht-remove! (table key)
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"Remove KEY from TABLE."
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(remhash key table))
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(defalias 'ht-remove 'ht-remove!)
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(defun ht-clear! (table)
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"Remove all keys from TABLE."
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(clrhash table)
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nil)
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(defalias 'ht-clear 'ht-clear!)
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(defun ht-map (function table)
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"Apply FUNCTION to each key-value pair of TABLE, and make a list of the results.
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FUNCTION is called with two arguments, KEY and VALUE."
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(let (results)
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(maphash
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(lambda (key value)
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(push (funcall function key value) results))
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table)
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results))
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(defmacro ht-amap (form table)
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"Anaphoric version of `ht-map'.
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For every key-value pair in TABLE, evaluate FORM with the
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variables KEY and VALUE bound."
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`(ht-map (lambda (key value) ,form) ,table))
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(defun ht-keys (table)
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"Return a list of all the keys in TABLE."
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(ht-amap key table))
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(defun ht-values (table)
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"Return a list of all the values in TABLE."
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(ht-amap value table))
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(defun ht-items (table)
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"Return a list of two-element lists '(key value) from TABLE."
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(ht-amap (list key value) table))
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(defalias 'ht-each 'maphash
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"Apply FUNCTION to each key-value pair of TABLE.
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Returns nil, used for side-effects only.")
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(defmacro ht-aeach (form table)
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"Anaphoric version of `ht-each'.
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For every key-value pair in TABLE, evaluate FORM with the
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variables key and value bound."
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`(ht-each (lambda (key value) ,form) ,table))
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(defun ht->plist (table)
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"Return a flat list '(key1 value1 key2 value2...) from TABLE.
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Note that hash tables are unordered, so this cannot be an exact
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inverse of `ht<-plist'. The following is not guaranteed:
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\(let ((data '(a b c d)))
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(equalp data
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(ht->plist (ht<-plist data))))"
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(apply 'append (ht-items table)))
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(defalias 'ht-to-plist 'ht->plist)
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(defun ht-copy (table)
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"Return a shallow copy of TABLE (keys and values are shared)."
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(copy-hash-table table))
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(defun ht->alist (table)
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"Return a list of two-element lists '(key . value) from TABLE.
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Note that hash tables are unordered, so this cannot be an exact
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inverse of `ht<-alist'. The following is not guaranteed:
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\(let ((data '((a . b) (c . d))))
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(equalp data
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(ht->alist (ht<-alist data))))"
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(ht-amap (cons key value) table))
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(defalias 'ht-to-alist 'ht->alist)
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(defalias 'ht? 'hash-table-p)
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(defalias 'ht-p 'hash-table-p)
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(defun ht-contains? (table key)
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"Return 't if TABLE contains KEY."
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(not (eq (ht-get table key 'ht--not-found) 'ht--not-found)))
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(defalias 'ht-contains-p 'ht-contains?)
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(defun ht-size (table)
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"Return the actual number of entries in TABLE."
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(hash-table-count table))
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(defun ht-empty? (table)
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"Return true if the actual number of entries in TABLE is zero."
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(zerop (ht-size table)))
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(defun ht-select (function table)
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"Return a hash table containing all entries in TABLE for which
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FUNCTION returns a truthy value.
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FUNCTION is called with two arguments, KEY and VALUE."
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(let ((results (ht-create)))
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(ht-each
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(lambda (key value)
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(when (funcall function key value)
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(ht-set! results key value)))
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table)
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results))
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(defun ht-reject (function table)
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"Return a hash table containing all entries in TABLE for which
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FUNCTION returns a falsy value.
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FUNCTION is called with two arguments, KEY and VALUE."
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(let ((results (ht-create)))
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(ht-each
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(lambda (key value)
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(unless (funcall function key value)
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(ht-set! results key value)))
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table)
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results))
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(defun ht-reject! (function table)
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"Delete entries from TABLE for which FUNCTION returns a falsy value.
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FUNCTION is called with two arguments, KEY and VALUE."
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(ht-each
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(lambda (key value)
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(when (funcall function key value)
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(remhash key table)))
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table)
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nil)
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(defalias 'ht-delete-if 'ht-reject!)
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(defun ht-find (function table)
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"Return (key, value) from TABLE for which FUNCTION returns a truthy value.
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Return nil otherwise.
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FUNCTION is called with two arguments, KEY and VALUE."
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(catch 'break
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(ht-each
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(lambda (key value)
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(when (funcall function key value)
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(throw 'break (list key value))))
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table)))
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(defun ht-equal? (table1 table2)
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"Return t if TABLE1 and TABLE2 have the same keys and values.
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Does not compare equality predicates."
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(let ((keys1 (ht-keys table1))
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(keys2 (ht-keys table2))
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(sentinel (make-symbol "ht-sentinel")))
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(and (equal (length keys1) (length keys2))
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(--all?
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(equal (ht-get table1 it)
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(ht-get table2 it sentinel))
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keys1))))
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(defalias 'ht-equal-p 'ht-equal?)
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(provide 'ht)
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;;; ht.el ends here
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