217 lines
7.9 KiB
EmacsLisp
217 lines
7.9 KiB
EmacsLisp
;;; parse-time.el --- parsing time strings -*- lexical-binding: t -*-
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;; Copyright (C) 1996, 2000-2024 Free Software Foundation, Inc.
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;; Author: Erik Naggum <erik@naggum.no>
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;; Keywords: util
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;; This file is part of GNU Emacs.
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;; GNU Emacs 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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;; GNU Emacs 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 GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; With the introduction of the `encode-time', `decode-time', and
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;; `format-time-string' functions, dealing with time became simpler in
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;; Emacs. However, parsing time strings is still largely a matter of
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;; heuristics and no common interface has been designed.
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;; `parse-time-string' parses a time in a string and returns a list of
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;; values, just like `decode-time', where unspecified elements in the
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;; string are returned as nil (except unspecified DST is returned as -1).
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;; `encode-time' may be applied on these values to obtain an internal
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;; time value.
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;;; Code:
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(require 'cl-lib)
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(require 'iso8601)
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(eval-when-compile (require 'subr-x))
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;; Byte-compiler warnings
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(defvar parse-time-elt)
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(defvar parse-time-val)
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(defsubst parse-time-string-chars (char)
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(cond ((<= ?a char ?z) ?a)
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((<= ?0 char ?9) ?0)
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((eq char ?+) 1)
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((eq char ?-) -1)
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((eq char ?:) ?d)))
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(defun parse-time-tokenize (string)
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"Tokenize STRING into substrings.
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Each substring is a run of \"valid\" characters, i.e., lowercase
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letters, digits, plus or minus signs or colons."
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(let ((start nil)
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(end (length string))
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(all-digits nil)
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(list ())
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(index 0)
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(c nil))
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(while (< index end)
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(while (and (< index end) ;Skip invalid characters.
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(not (setq c (parse-time-string-chars (aref string index)))))
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(cl-incf index))
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(setq start index
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all-digits (eq c ?0))
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(while (and (< (cl-incf index) end) ;Scan valid characters.
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(setq c (parse-time-string-chars (aref string index))))
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(setq all-digits (and all-digits (eq c ?0))))
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(if (<= index end)
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(push (if all-digits (cl-parse-integer string :start start :end index)
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(substring string start index))
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list)))
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(nreverse list)))
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(defvar parse-time-months '(("jan" . 1) ("feb" . 2) ("mar" . 3)
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("apr" . 4) ("may" . 5) ("jun" . 6)
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("jul" . 7) ("aug" . 8) ("sep" . 9)
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("oct" . 10) ("nov" . 11) ("dec" . 12)
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("january" . 1) ("february" . 2)
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("march" . 3) ("april" . 4) ("june" . 6)
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("july" . 7) ("august" . 8)
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("september" . 9) ("october" . 10)
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("november" . 11) ("december" . 12)))
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(defvar parse-time-weekdays '(("sun" . 0) ("mon" . 1) ("tue" . 2)
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("wed" . 3) ("thu" . 4) ("fri" . 5)
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("sat" . 6) ("sunday" . 0) ("monday" . 1)
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("tuesday" . 2) ("wednesday" . 3)
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("thursday" . 4) ("friday" . 5)
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("saturday" . 6)))
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(defvar parse-time-zoneinfo `(("z" 0) ("ut" 0) ("gmt" 0)
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("pst" ,(* -8 3600)) ("pdt" ,(* -7 3600) t)
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("mst" ,(* -7 3600)) ("mdt" ,(* -6 3600) t)
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("cst" ,(* -6 3600)) ("cdt" ,(* -5 3600) t)
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("est" ,(* -5 3600)) ("edt" ,(* -4 3600) t))
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"(zoneinfo seconds-off daylight-savings-time-p)")
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(defvar parse-time-rules
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`(((6) parse-time-weekdays)
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((3) (1 31))
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((4) parse-time-months)
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((5) (100))
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((2 1 0)
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,(lambda () (and (stringp parse-time-elt)
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(= (length parse-time-elt) 8)
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(= (aref parse-time-elt 2) ?:)
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(= (aref parse-time-elt 5) ?:)))
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[0 2] [3 5] [6 8])
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((8 7) parse-time-zoneinfo
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,(lambda () (car parse-time-val))
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,(lambda () (cadr parse-time-val)))
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((8)
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,(lambda ()
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(and (stringp parse-time-elt)
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(= 5 (length parse-time-elt))
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(or (= (aref parse-time-elt 0) ?+)
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(= (aref parse-time-elt 0) ?-))))
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,(lambda () (* 60 (+ (cl-parse-integer parse-time-elt :start 3 :end 5)
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(* 60 (cl-parse-integer parse-time-elt :start 1 :end 3)))
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(if (= (aref parse-time-elt 0) ?-) -1 1))))
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((5 4 3)
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,(lambda () (and (stringp parse-time-elt)
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(= (length parse-time-elt) 10)
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(= (aref parse-time-elt 4) ?-)
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(= (aref parse-time-elt 7) ?-)))
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[0 4] [5 7] [8 10])
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((2 1 0)
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,(lambda () (and (stringp parse-time-elt)
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(= (length parse-time-elt) 5)
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(= (aref parse-time-elt 2) ?:)))
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[0 2] [3 5] ,(lambda () 0))
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((2 1 0)
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,(lambda () (and (stringp parse-time-elt)
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(= (length parse-time-elt) 4)
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(= (aref parse-time-elt 1) ?:)))
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[0 1] [2 4] ,(lambda () 0))
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((2 1 0)
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,(lambda () (and (stringp parse-time-elt)
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(= (length parse-time-elt) 7)
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(= (aref parse-time-elt 1) ?:)))
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[0 1] [2 4] [5 7])
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((5) (50 110) ,(lambda () (+ 1900 parse-time-elt)))
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((5) (0 49) ,(lambda () (+ 2000 parse-time-elt))))
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"(slots predicate extractor...)")
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;;;###autoload(put 'parse-time-rules 'risky-local-variable t)
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;;;###autoload
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(defun parse-time-string (string &optional form)
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"Parse the time in STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ).
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STRING should be an ISO 8601 time string, e.g., \"2020-01-15T16:12:21-08:00\",
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or something resembling an RFC 822 (or later) date-time, e.g.,
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\"Wed, 15 Jan 2020 16:12:21 -0800\". This function is
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somewhat liberal in what format it accepts, and will attempt to
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return a \"likely\" value even for somewhat malformed strings.
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The values returned are identical to those of `decode-time', but
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any unknown values other than DST are returned as nil, and an
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unknown DST value is returned as -1.
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See `decode-time' for the meaning of FORM."
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(condition-case ()
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(iso8601-parse string form)
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(wrong-type-argument
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(let ((time (list nil nil nil nil nil nil nil -1 nil))
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(temp (parse-time-tokenize (downcase string))))
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(while temp
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(let ((parse-time-elt (pop temp))
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(rules parse-time-rules)
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(exit nil))
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(while (and rules (not exit))
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(let* ((rule (pop rules))
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(slots (pop rule))
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(predicate (pop rule))
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(parse-time-val))
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(when (and (not (nth (car slots) time)) ;not already set
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(setq parse-time-val
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(cond ((and (consp predicate)
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(not (functionp predicate)))
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(and (numberp parse-time-elt)
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(<= (car predicate) parse-time-elt)
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(or (not (cdr predicate))
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(<= parse-time-elt
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(cadr predicate)))
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parse-time-elt))
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((symbolp predicate)
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(cdr (assoc parse-time-elt
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(symbol-value predicate))))
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((funcall predicate)))))
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(setq exit t)
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(while slots
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(let ((new-val (if rule
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(let ((this (pop rule)))
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(if (vectorp this)
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(cl-parse-integer
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parse-time-elt
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:start (aref this 0)
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:end (aref this 1))
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(funcall this)))
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parse-time-val)))
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(setf (nth (pop slots) time) new-val))))))))
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time))))
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(defun parse-iso8601-time-string (date-string &optional form)
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"Parse an ISO 8601 time string, such as \"2020-01-15T16:12:21-08:00\".
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Fall back on parsing something resembling an RFC 822 (or later) date-time.
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This function is like `parse-time-string' except that it returns
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a Lisp timestamp when successful.
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See `decode-time' for the meaning of FORM."
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(when-let ((time (parse-time-string date-string form)))
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(encode-time time)))
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(provide 'parse-time)
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;;; parse-time.el ends here
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