mirror of https://github.com/Wilfred/difftastic/
133 lines
3.8 KiB
EmacsLisp
133 lines
3.8 KiB
EmacsLisp
;;; 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: 0.6
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;; Keywords: hash table, hash map, hash
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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 utility library for Emacs.
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;;
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;; See documentation on https://github.com/Wilfred/ht.el
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;;; Todo:
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;; * Full unit tests
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;;; Code:
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(eval-when-compile (require 'cl))
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(defun ht-create ()
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"Create an empty hash table."
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(make-hash-table :test 'equal))
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(defun ht-from-alist (alist)
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"Create a hash table with initial values according to ALIST."
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(let ((h (ht-create)))
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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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;; 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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"Returns 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-from-plist (plist)
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"Create a hash table with initial values according to PLIST."
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(let ((h (ht-create)))
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(dolist (pair (ht/group-pairs plist) h)
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(let ((key (first pair))
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(value (second pair)))
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(ht-set h key value)))))
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(defun ht-from-alist (alist)
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"Create a hash table with initial values according to ALIST."
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(let ((h (ht-create)))
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(dolist (pair 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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(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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(defun ht-remove (table key)
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"Remove KEY from TABLE."
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(remhash key table))
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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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(defun ht-keys (table)
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"Return a list of all the keys in TABLE."
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(let ((keys))
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(maphash (lambda (key value) (setq keys (cons key keys))) table)
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keys))
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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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(let ((values))
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(maphash (lambda (key value) (setq values (cons value values))) table)
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values))
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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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(let ((items))
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(maphash (lambda (key value) (setq items (cons (list key value) items))) table)
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items))
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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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(provide 'ht)
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;;; ht.el ends here
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