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This function is generally useful. * lisp/emacs-lisp/syntax.el (syntax-propertize-wholelines): Add docstring.
718 lines
31 KiB
EmacsLisp
718 lines
31 KiB
EmacsLisp
;;; syntax.el --- helper functions to find syntactic context -*- lexical-binding: t -*-
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;; Copyright (C) 2000-2021 Free Software Foundation, Inc.
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: internal
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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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;; The main exported function is `syntax-ppss'. You might also need
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;; to call `syntax-ppss-flush-cache' or to add it to
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;; before-change-functions'(although this is automatically done by
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;; syntax-ppss when needed, but that might fail if syntax-ppss is
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;; called in a context where before-change-functions is temporarily
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;; let-bound to nil).
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;;; Todo:
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;; - do something about the case where the syntax-table is changed.
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;; This typically happens with tex-mode and its `$' operator.
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;; - new functions `syntax-state', ... to replace uses of parse-partial-state
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;; with something higher-level (similar to syntax-ppss-context).
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;; - interaction with mmm-mode.
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;;; Code:
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;; Note: PPSS stands for `parse-partial-sexp state'
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(eval-when-compile (require 'cl-lib))
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;;; Applying syntax-table properties where needed.
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(defvar syntax-propertize-function nil
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;; Rather than a -functions hook, this is a -function because it's easier
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;; to do a single scan than several scans: with multiple scans, one cannot
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;; assume that the text before point has been propertized, so syntax-ppss
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;; gives unreliable results (and stores them in its cache to boot, so we'd
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;; have to flush that cache between each function, and we couldn't use
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;; syntax-ppss-flush-cache since that would not only flush the cache but also
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;; reset syntax-propertize--done which should not be done in this case).
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"Mode-specific function to apply `syntax-table' text properties.
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It is the work horse of `syntax-propertize', which is called by things like
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Font-Lock and indentation.
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It is given two arguments, START and END: the start and end of the text to
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which `syntax-table' might need to be applied. Major modes can use this to
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override the buffer's syntax table for special syntactic constructs that
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cannot be handled just by the buffer's syntax-table.
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The specified function may call `syntax-ppss' on any position
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before END, but if it calls `syntax-ppss' on some
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position and later modifies the buffer on some earlier position,
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then it is its responsibility to call `syntax-ppss-flush-cache' to flush
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the now obsolete ppss info from the cache.
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Note: When this variable is a function, it must apply _all_ the
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`syntax-table' properties needed in the given text interval.
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Using both this function and other means to apply these
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properties won't work properly.")
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(defvar syntax-propertize-chunk-size 500)
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(defvar-local syntax-propertize-extend-region-functions
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'(syntax-propertize-wholelines)
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"Special hook run just before proceeding to propertize a region.
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This is used to allow major modes to help `syntax-propertize' find safe buffer
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positions as beginning and end of the propertized region. Its most common use
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is to solve the problem of /identification/ of multiline elements by providing
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a function that tries to find such elements and move the boundaries such that
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they do not fall in the middle of one.
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Each function is called with two arguments (START and END) and it should return
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either a cons (NEW-START . NEW-END) or nil if no adjustment should be made.
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These functions are run in turn repeatedly until they all return nil.
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Put first the functions more likely to cause a change and cheaper to compute.")
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;; Mark it as a special hook which doesn't use any global setting
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;; (i.e. doesn't obey the element t in the buffer-local value).
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(cl-defstruct (ppss
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(:constructor make-ppss)
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(:copier nil)
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(:type list))
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(depth nil :documentation "Depth in parens.")
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(innermost-start
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nil :documentation
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"Character address of start of innermost containing list; nil if none.")
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(last-complete-sexp-start
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nil :documentation
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"Character address of start of last complete sexp terminated.")
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(string-terminator nil :documentation "\
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Non-nil if inside a string.
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\(it is the character that will terminate the string, or t if the
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string should be terminated by a generic string delimiter.)")
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(comment-depth nil :documentation "\
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nil if outside a comment, t if inside a non-nestable comment,
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else an integer (the current comment nesting).")
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(quoted-p nil :documentation "t if following a quote character.")
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(min-depth
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nil :documentation "The minimum depth in parens encountered during this scan.")
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(comment-style nil :documentation "Style of comment, if any.")
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(comment-or-string-start
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nil :documentation
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"Character address of start of comment or string; nil if not in one.")
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(open-parens
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nil :documentation
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"List of positions of currently open parens, outermost first.")
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(two-character-syntax nil :documentation "\
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When the last position scanned holds the first character of a
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\(potential) two character construct, the syntax of that position,
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otherwise nil. That construct can be a two character comment
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delimiter or an Escaped or Char-quoted character."))
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(defun syntax-propertize-wholelines (start end)
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"Extend the region delimited by START and END to whole lines.
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This function is useful for
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`syntax-propertize-extend-region-functions';
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see Info node `(elisp) Syntax Properties'."
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(goto-char start)
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(cons (line-beginning-position)
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(progn (goto-char end)
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(if (bolp) (point) (line-beginning-position 2)))))
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(defun syntax-propertize-multiline (beg end)
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"Let `syntax-propertize' pay attention to the syntax-multiline property."
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(when (and (> beg (point-min))
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(get-text-property (1- beg) 'syntax-multiline))
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(setq beg (or (previous-single-property-change beg 'syntax-multiline)
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(point-min))))
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;;
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(when (get-text-property end 'syntax-multiline)
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(setq end (or (text-property-any end (point-max)
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'syntax-multiline nil)
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(point-max))))
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(cons beg end))
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(defun syntax-propertize--shift-groups-and-backrefs (re n)
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(let ((new-re (replace-regexp-in-string
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"\\\\(\\?\\([0-9]+\\):"
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(lambda (s)
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(replace-match
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(number-to-string
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(+ n (string-to-number (match-string 1 s))))
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t t s 1))
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re t t))
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(pos 0))
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(while (string-match "\\\\\\([0-9]+\\)" new-re pos)
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(setq pos (+ 1 (match-beginning 1)))
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(when (save-match-data
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;; With \N, the \ must be in a subregexp context, i.e.,
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;; not in a character class or in a \{\} repetition.
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(subregexp-context-p new-re (match-beginning 0)))
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(let ((shifted (+ n (string-to-number (match-string 1 new-re)))))
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(when (> shifted 9)
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(error "There may be at most nine back-references"))
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(setq new-re (replace-match (number-to-string shifted)
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t t new-re 1)))))
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new-re))
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(defmacro syntax-propertize-precompile-rules (&rest rules)
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"Return a precompiled form of RULES to pass to `syntax-propertize-rules'.
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The arg RULES can be of the same form as in `syntax-propertize-rules'.
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The return value is an object that can be passed as a rule to
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`syntax-propertize-rules'.
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I.e. this is useful only when you want to share rules among several
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`syntax-propertize-function's."
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(declare (debug syntax-propertize-rules))
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;; Precompile? Yeah, right!
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;; Seriously, tho, this is a macro for 2 reasons:
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;; - we could indeed do some pre-compilation at some point in the future,
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;; e.g. fi/when we switch to a DFA-based implementation of
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;; syntax-propertize-rules.
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;; - this lets Edebug properly annotate the expressions inside RULES.
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`',rules)
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(defmacro syntax-propertize-rules (&rest rules)
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"Make a function that applies RULES for use in `syntax-propertize-function'.
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The function will scan the buffer, applying the rules where they match.
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The buffer is scanned a single time, like \"lex\" would, rather than once
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per rule.
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Each RULE can be a symbol, in which case that symbol's value should be,
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at macro-expansion time, a precompiled set of rules, as returned
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by `syntax-propertize-precompile-rules'.
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Otherwise, RULE should have the form (REGEXP HIGHLIGHT1 ... HIGHLIGHTn), where
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REGEXP is an expression (evaluated at time of macro-expansion) that returns
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a regexp, and where HIGHLIGHTs have the form (NUMBER SYNTAX) which means to
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apply the property SYNTAX to the chars matched by the subgroup NUMBER
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of the regular expression, if NUMBER did match.
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SYNTAX is an expression that returns a value to apply as `syntax-table'
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property. Some expressions are handled specially:
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- if SYNTAX is a string, then it is converted with `string-to-syntax';
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- if SYNTAX has the form (prog1 EXP . EXPS) then the value returned by EXP
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will be applied to the buffer before running EXPS and if EXP is a string it
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is also converted with `string-to-syntax'.
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The SYNTAX expression is responsible to save the `match-data' if needed
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for subsequent HIGHLIGHTs.
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Also SYNTAX is free to move point, in which case RULES may not be applied to
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some parts of the text or may be applied several times to other parts.
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Note: There may be at most nine back-references in the REGEXPs of
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all RULES in total."
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(declare (debug (&rest &or symbolp ;FIXME: edebug this eval step.
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(form &rest
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(numberp
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[&or stringp ;FIXME: Use &wrap
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("prog1" [&or stringp def-form] def-body)
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def-form])))))
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(let ((newrules nil))
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(while rules
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(if (symbolp (car rules))
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(setq rules (append (symbol-value (pop rules)) rules))
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(push (pop rules) newrules)))
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(setq rules (nreverse newrules)))
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(let* ((offset 0)
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(branches '())
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;; We'd like to use a real DFA-based lexer, usually, but since Emacs
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;; doesn't have one yet, we fallback on building one large regexp
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;; and use groups to determine which branch of the regexp matched.
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(re
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(mapconcat
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(lambda (rule)
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(let* ((orig-re (eval (car rule) t))
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(re orig-re))
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(when (and (assq 0 rule) (cdr rules))
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;; If there's more than 1 rule, and the rule want to apply
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;; highlight to match 0, create an extra group to be able to
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;; tell when *this* match 0 has succeeded.
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(cl-incf offset)
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(setq re (concat "\\(" re "\\)")))
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(setq re (syntax-propertize--shift-groups-and-backrefs re offset))
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(let ((code '())
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(condition
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(cond
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((assq 0 rule) (if (zerop offset) t
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`(match-beginning ,offset)))
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((and (cdr rule) (null (cddr rule)))
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`(match-beginning ,(+ offset (car (cadr rule)))))
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(t
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`(or ,@(mapcar
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(lambda (case)
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`(match-beginning ,(+ offset (car case))))
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(cdr rule))))))
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(nocode t)
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(offset offset))
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;; If some of the subgroup rules include Elisp code, then we
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;; need to set the match-data so it's consistent with what the
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;; code expects. If not, then we can simply use shifted
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;; offset in our own code.
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(unless (zerop offset)
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(dolist (case (cdr rule))
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(unless (stringp (cadr case))
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(setq nocode nil)))
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(unless nocode
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(push `(let ((md (match-data 'ints)))
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;; Keep match 0 as is, but shift everything else.
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(setcdr (cdr md) (nthcdr ,(* (1+ offset) 2) md))
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(set-match-data md))
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code)
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(setq offset 0)))
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;; Now construct the code for each subgroup rules.
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(dolist (case (cdr rule))
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(cl-assert (null (cddr case)))
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(let* ((gn (+ offset (car case)))
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(action (nth 1 case))
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(thiscode
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(cond
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((stringp action)
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`((put-text-property
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(match-beginning ,gn) (match-end ,gn)
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'syntax-table
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',(string-to-syntax action))))
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((eq (car-safe action) 'ignore)
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(cdr action))
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((eq (car-safe action) 'prog1)
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(if (stringp (nth 1 action))
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`((put-text-property
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(match-beginning ,gn) (match-end ,gn)
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'syntax-table
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',(string-to-syntax (nth 1 action)))
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,@(nthcdr 2 action))
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`((let ((mb (match-beginning ,gn))
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(me (match-end ,gn)))
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,(macroexp-let2 nil syntax (nth 1 action)
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`(progn
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(if ,syntax
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(put-text-property
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mb me 'syntax-table ,syntax))
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,@(nthcdr 2 action)))))))
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(t
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`((let ((mb (match-beginning ,gn))
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(me (match-end ,gn))
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(syntax ,action))
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(if syntax
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(put-text-property
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mb me 'syntax-table syntax))))))))
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(if (or (not (cddr rule)) (zerop gn))
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(setq code (nconc (nreverse thiscode) code))
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(push `(if (match-beginning ,gn)
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;; Try and generate clean code with no
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;; extraneous progn.
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,(if (null (cdr thiscode))
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(car thiscode)
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`(progn ,@thiscode)))
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code))))
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(push (cons condition (nreverse code))
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branches))
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(cl-incf offset (regexp-opt-depth orig-re))
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re))
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rules
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"\\|")))
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`(lambda (start end)
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(goto-char start)
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(while (and (< (point) end)
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(re-search-forward ,re end t))
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(cond ,@(nreverse branches))))))
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(defun syntax-propertize-via-font-lock (keywords)
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"Propertize for syntax using font-lock syntax.
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KEYWORDS obeys the format used in `font-lock-syntactic-keywords'.
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The return value is a function (with two parameters, START and
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END) suitable for `syntax-propertize-function'."
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(lambda (start end)
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(with-no-warnings
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(let ((font-lock-syntactic-keywords keywords))
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(font-lock-fontify-syntactic-keywords-region start end)
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;; In case it was eval'd/compiled.
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(setq keywords font-lock-syntactic-keywords)))))
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(defvar-local syntax-ppss-table nil
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"Syntax-table to use during `syntax-ppss', if any.")
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(defvar-local syntax-propertize--inhibit-flush nil
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"If non-nil, `syntax-ppss-flush-cache' only flushes the ppss cache.
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Otherwise it flushes both the ppss cache and the properties
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set by `syntax-propertize'")
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(defun syntax-propertize (pos)
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"Ensure that syntax-table properties are set until POS (a buffer point)."
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(when (< syntax-propertize--done pos)
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(if (memq syntax-propertize-function '(nil ignore))
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(setq syntax-propertize--done (max (point-max) pos))
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;; (message "Needs to syntax-propertize from %s to %s"
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;; syntax-propertize--done pos)
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(setq-local parse-sexp-lookup-properties t)
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(when (< syntax-propertize--done (point-min))
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;; *Usually* syntax-propertize is called via syntax-ppss which
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;; takes care of adding syntax-ppss-flush-cache to b-c-f, but this
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;; is not *always* the case, so since we share a single "flush" function
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;; between syntax-ppss and syntax-propertize, we also have to make
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;; sure the flush function is installed here (bug#29767).
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(add-hook 'before-change-functions
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#'syntax-ppss-flush-cache 99 t))
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(save-excursion
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(with-silent-modifications
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(with-syntax-table (or syntax-ppss-table (syntax-table))
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(make-local-variable 'syntax-propertize--done) ;Just in case!
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(let* ((start (max (min syntax-propertize--done (point-max))
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(point-min)))
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(end (max pos
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(min (point-max)
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(+ start syntax-propertize-chunk-size))))
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(first t)
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(repeat t))
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(while repeat
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(setq repeat nil)
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(run-hook-wrapped
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'syntax-propertize-extend-region-functions
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(lambda (f)
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(let ((new (funcall f start end))
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;; Avoid recursion!
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(syntax-propertize--done most-positive-fixnum))
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(if (or (null new)
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(and (>= (car new) start) (<= (cdr new) end)))
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nil
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(setq start (car new))
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(setq end (cdr new))
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;; If there's been a change, we should go through the
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;; list again since this new position may
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;; warrant a different answer from one of the funs we've
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;; already seen.
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(unless first (setq repeat t))))
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(setq first nil))))
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;; Flush ppss cache between the original value of `start' and that
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;; set above by syntax-propertize-extend-region-functions.
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(syntax-ppss-flush-cache start)
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;; Move the limit before calling the function, so the function
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;; can use syntax-ppss.
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(setq syntax-propertize--done end)
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;; (message "syntax-propertizing from %s to %s" start end)
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(remove-text-properties start end
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'(syntax-table nil syntax-multiline nil))
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;; Make sure we only let-bind it buffer-locally.
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(make-local-variable 'syntax-propertize--inhibit-flush)
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;; Let-bind `syntax-propertize--done' to avoid infinite recursion!
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(let ((syntax-propertize--done most-positive-fixnum)
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;; Let `syntax-propertize-function' call
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;; `syntax-ppss-flush-cache' without worries.
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(syntax-propertize--inhibit-flush t))
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(funcall syntax-propertize-function start end)))))))))
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;;; Link syntax-propertize with syntax.c.
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(defvar syntax-propertize-chunks
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;; We're not sure how far we'll go. In my tests, using chunks of 2000
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;; brings the overhead to something negligible. Passing ‘charpos’ directly
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;; also works (basically works line-by-line) but results in an overhead which
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;; I thought was a bit too high (like around 50%).
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2000)
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(defun internal--syntax-propertize (charpos)
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;; FIXME: Called directly from C.
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(save-match-data
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(syntax-propertize (min (+ syntax-propertize-chunks charpos) (point-max)))))
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;;; Incrementally compute and memoize parser state.
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(defsubst syntax-ppss-depth (ppss)
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(nth 0 ppss))
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(defun syntax-ppss-toplevel-pos (ppss)
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"Get the latest syntactically outermost position found in a syntactic scan.
|
||
PPSS is a scan state, as returned by `parse-partial-sexp' or `syntax-ppss'.
|
||
An \"outermost position\" means one that it is outside of any syntactic entity:
|
||
outside of any parentheses, comments, or strings encountered in the scan.
|
||
If no such position is recorded in PPSS (because the end of the scan was
|
||
itself at the outermost level), return nil."
|
||
(or (car (nth 9 ppss))
|
||
(nth 8 ppss)))
|
||
|
||
(defsubst syntax-ppss-context (ppss)
|
||
"Say whether PPSS is a string, a comment, or something else.
|
||
If PPSS is a string, the symbol `string' is returned. If it's a
|
||
comment, the symbol `comment' is returned. If it's something
|
||
else, nil is returned."
|
||
(cond
|
||
((nth 3 ppss) 'string)
|
||
((nth 4 ppss) 'comment)
|
||
(t nil)))
|
||
|
||
(defvar syntax-ppss-max-span 20000
|
||
"Threshold below which cache info is deemed unnecessary.
|
||
We try to make sure that cache entries are at least this far apart
|
||
from each other, to avoid keeping too much useless info.")
|
||
|
||
(defvar syntax-begin-function nil
|
||
"Function to move back outside of any comment/string/paren.
|
||
This function should move the cursor back to some syntactically safe
|
||
point (where the PPSS is equivalent to nil).")
|
||
(make-obsolete-variable 'syntax-begin-function nil "25.1")
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Several caches.
|
||
;;
|
||
;; Because `syntax-ppss' is equivalent to (parse-partial-sexp
|
||
;; (POINT-MIN) x), we need either to empty the cache when we narrow
|
||
;; the buffer, which is suboptimal, or we need to use several caches.
|
||
;; We use two of them, one for widened buffer, and one for narrowing.
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(defvar-local syntax-ppss-wide nil
|
||
"Cons of two elements (LAST . CACHE).
|
||
Where LAST is a pair (LAST-POS . LAST-PPS) caching the last invocation
|
||
and CACHE is a list of (POS . PPSS) pairs, in decreasing POS order.
|
||
These are valid when the buffer has no restriction.")
|
||
|
||
(defvar-local syntax-ppss-narrow nil
|
||
"Same as `syntax-ppss-wide' but for a narrowed buffer.")
|
||
|
||
(defvar-local syntax-ppss-narrow-start nil
|
||
"Start position of the narrowing for `syntax-ppss-narrow'.")
|
||
|
||
(define-obsolete-function-alias 'syntax-ppss-after-change-function
|
||
#'syntax-ppss-flush-cache "27.1")
|
||
(defun syntax-ppss-flush-cache (beg &rest ignored)
|
||
"Flush the cache of `syntax-ppss' starting at position BEG."
|
||
;; Set syntax-propertize to refontify anything past beg.
|
||
(unless syntax-propertize--inhibit-flush
|
||
(setq syntax-propertize--done (min beg syntax-propertize--done)))
|
||
;; Flush invalid cache entries.
|
||
(dolist (cell (list syntax-ppss-wide syntax-ppss-narrow))
|
||
(pcase cell
|
||
(`(,last . ,cache)
|
||
(while (and cache (> (caar cache) beg))
|
||
(setq cache (cdr cache)))
|
||
;; Throw away `last' value if made invalid.
|
||
(when (< beg (or (car last) 0))
|
||
;; If syntax-begin-function jumped to BEG, then the old state at BEG can
|
||
;; depend on the text after BEG (which is presumably changed). So if
|
||
;; BEG=(car (nth 10 syntax-ppss-last)) don't reuse that data because the
|
||
;; assumed nil state at BEG may not be valid any more.
|
||
(if (<= beg (or (syntax-ppss-toplevel-pos (cdr last))
|
||
(nth 3 last)
|
||
0))
|
||
(setq last nil)
|
||
(setcar last nil)))
|
||
;; Unregister if there's no cache left. Sadly this doesn't work
|
||
;; because `before-change-functions' is temporarily bound to nil here.
|
||
;; (unless cache
|
||
;; (remove-hook 'before-change-functions #'syntax-ppss-flush-cache t))
|
||
(setcar cell last)
|
||
(setcdr cell cache)))
|
||
))
|
||
|
||
;;; FIXME: Explain this variable. Currently only its last (5th) slot is used.
|
||
;;; Perhaps the other slots should be removed?
|
||
(defvar syntax-ppss-stats
|
||
[(0 . 0) (0 . 0) (0 . 0) (0 . 0) (0 . 0) (2 . 2500)])
|
||
(defun syntax-ppss-stats ()
|
||
(mapcar (lambda (x)
|
||
(condition-case nil
|
||
(cons (car x) (/ (cdr x) (car x)))
|
||
(error nil)))
|
||
syntax-ppss-stats))
|
||
(defun syntax-ppss--update-stats (i old new)
|
||
(let ((pair (aref syntax-ppss-stats i)))
|
||
(cl-incf (car pair))
|
||
(cl-incf (cdr pair) (- new old))))
|
||
|
||
(defun syntax-ppss--data ()
|
||
(if (eq (point-min) 1)
|
||
(progn
|
||
(unless syntax-ppss-wide
|
||
(setq syntax-ppss-wide (cons nil nil)))
|
||
syntax-ppss-wide)
|
||
(unless (eq syntax-ppss-narrow-start (point-min))
|
||
(setq syntax-ppss-narrow-start (point-min))
|
||
(setq syntax-ppss-narrow (cons nil nil)))
|
||
syntax-ppss-narrow))
|
||
|
||
(defun syntax-ppss (&optional pos)
|
||
"Parse-Partial-Sexp State at POS, defaulting to point.
|
||
The returned value is the same as that of `parse-partial-sexp'
|
||
run from `point-min' to POS except that values at positions 2 and 6
|
||
in the returned list (counting from 0) cannot be relied upon.
|
||
Point is at POS when this function returns.
|
||
|
||
It is necessary to call `syntax-ppss-flush-cache' explicitly if
|
||
this function is called while `before-change-functions' is
|
||
temporarily let-bound, or if the buffer is modified without
|
||
running the hook."
|
||
;; Default values.
|
||
(unless pos (setq pos (point)))
|
||
(syntax-propertize pos)
|
||
;;
|
||
(with-syntax-table (or syntax-ppss-table (syntax-table))
|
||
(let* ((cell (syntax-ppss--data))
|
||
(ppss-last (car cell))
|
||
(ppss-cache (cdr cell))
|
||
(old-ppss (cdr ppss-last))
|
||
(old-pos (car ppss-last))
|
||
(ppss nil)
|
||
(pt-min (point-min)))
|
||
(if (and old-pos (> old-pos pos)) (setq old-pos nil))
|
||
;; Use the OLD-POS if usable and close. Don't update the `last' cache.
|
||
(condition-case nil
|
||
(if (and old-pos (< (- pos old-pos)
|
||
;; The time to use syntax-begin-function and
|
||
;; find PPSS is assumed to be about 2 * distance.
|
||
(let ((pair (aref syntax-ppss-stats 5)))
|
||
(/ (* 2 (cdr pair)) (car pair)))))
|
||
(progn
|
||
(syntax-ppss--update-stats 0 old-pos pos)
|
||
(parse-partial-sexp old-pos pos nil nil old-ppss))
|
||
|
||
(cond
|
||
;; Use OLD-PPSS if possible and close enough.
|
||
((and (not old-pos) old-ppss
|
||
;; If `pt-min' is too far from `pos', we could try to use
|
||
;; other positions in (nth 9 old-ppss), but that doesn't
|
||
;; seem to happen in practice and it would complicate this
|
||
;; code (and the before-change-function code even more).
|
||
;; But maybe it would be useful in "degenerate" cases such
|
||
;; as when the whole file is wrapped in a set
|
||
;; of parentheses.
|
||
(setq pt-min (or (syntax-ppss-toplevel-pos old-ppss)
|
||
(nth 2 old-ppss)))
|
||
(<= pt-min pos) (< (- pos pt-min) syntax-ppss-max-span))
|
||
(syntax-ppss--update-stats 1 pt-min pos)
|
||
(setq ppss (parse-partial-sexp pt-min pos)))
|
||
;; The OLD-* data can't be used. Consult the cache.
|
||
(t
|
||
(let ((cache-pred nil)
|
||
(cache ppss-cache)
|
||
(pt-min (point-min))
|
||
;; I differentiate between PT-MIN and PT-BEST because
|
||
;; I feel like it might be important to ensure that the
|
||
;; cache is only filled with 100% sure data (whereas
|
||
;; syntax-begin-function might return incorrect data).
|
||
;; Maybe that's just stupid.
|
||
(pt-best (point-min))
|
||
(ppss-best nil))
|
||
;; look for a usable cache entry.
|
||
(while (and cache (< pos (caar cache)))
|
||
(setq cache-pred cache)
|
||
(setq cache (cdr cache)))
|
||
(if cache (setq pt-min (caar cache) ppss (cdar cache)))
|
||
|
||
;; Setup the before-change function if necessary.
|
||
(unless (or ppss-cache ppss-last)
|
||
;; Note: combine-change-calls-1 needs to be kept in sync
|
||
;; with this!
|
||
(add-hook 'before-change-functions
|
||
#'syntax-ppss-flush-cache
|
||
;; We should be either the very last function on
|
||
;; before-change-functions or the very first on
|
||
;; after-change-functions.
|
||
99 t))
|
||
|
||
;; Use the best of OLD-POS and CACHE.
|
||
(if (or (not old-pos) (< old-pos pt-min))
|
||
(setq pt-best pt-min ppss-best ppss)
|
||
(syntax-ppss--update-stats 4 old-pos pos)
|
||
(setq pt-best old-pos ppss-best old-ppss))
|
||
|
||
;; Use the `syntax-begin-function' if available.
|
||
;; We could try using that function earlier, but:
|
||
;; - The result might not be 100% reliable, so it's better to use
|
||
;; the cache if available.
|
||
;; - The function might be slow.
|
||
;; - If this function almost always finds a safe nearby spot,
|
||
;; the cache won't be populated, so consulting it is cheap.
|
||
(when (and syntax-begin-function
|
||
(progn (goto-char pos)
|
||
(funcall syntax-begin-function)
|
||
;; Make sure it's better.
|
||
(> (point) pt-best))
|
||
;; Simple sanity checks.
|
||
(< (point) pos) ; backward-paragraph can fail here.
|
||
(not (memq (get-text-property (point) 'face)
|
||
'(font-lock-string-face font-lock-doc-face
|
||
font-lock-comment-face))))
|
||
(syntax-ppss--update-stats 5 (point) pos)
|
||
(setq pt-best (point) ppss-best nil))
|
||
|
||
(cond
|
||
;; Quick case when we found a nearby pos.
|
||
((< (- pos pt-best) syntax-ppss-max-span)
|
||
(syntax-ppss--update-stats 2 pt-best pos)
|
||
(setq ppss (parse-partial-sexp pt-best pos nil nil ppss-best)))
|
||
;; Slow case: compute the state from some known position and
|
||
;; populate the cache so we won't need to do it again soon.
|
||
(t
|
||
(syntax-ppss--update-stats 3 pt-min pos)
|
||
|
||
;; If `pt-min' is too far, add a few intermediate entries.
|
||
(while (> (- pos pt-min) (* 2 syntax-ppss-max-span))
|
||
(setq ppss (parse-partial-sexp
|
||
pt-min (setq pt-min (/ (+ pt-min pos) 2))
|
||
nil nil ppss))
|
||
(push (cons pt-min ppss)
|
||
(if cache-pred (cdr cache-pred) ppss-cache)))
|
||
|
||
;; Compute the actual return value.
|
||
(setq ppss (parse-partial-sexp pt-min pos nil nil ppss))
|
||
|
||
;; Debugging check.
|
||
;; (let ((real-ppss (parse-partial-sexp (point-min) pos)))
|
||
;; (setcar (last ppss 4) 0)
|
||
;; (setcar (last real-ppss 4) 0)
|
||
;; (setcar (last ppss 8) nil)
|
||
;; (setcar (last real-ppss 8) nil)
|
||
;; (unless (equal ppss real-ppss)
|
||
;; (message "!!Syntax: %s != %s" ppss real-ppss)
|
||
;; (setq ppss real-ppss)))
|
||
|
||
;; Store it in the cache.
|
||
(let ((pair (cons pos ppss)))
|
||
(if cache-pred
|
||
(if (> (- (caar cache-pred) pos) syntax-ppss-max-span)
|
||
(push pair (cdr cache-pred))
|
||
(setcar cache-pred pair))
|
||
(if (or (null ppss-cache)
|
||
(> (- (caar ppss-cache) pos)
|
||
syntax-ppss-max-span))
|
||
(push pair ppss-cache)
|
||
(setcar ppss-cache pair)))))))))
|
||
|
||
(setq ppss-last (cons pos ppss))
|
||
(setcar cell ppss-last)
|
||
(setcdr cell ppss-cache)
|
||
ppss)
|
||
(args-out-of-range
|
||
;; If the buffer is more narrowed than when we built the cache,
|
||
;; we may end up calling parse-partial-sexp with a position before
|
||
;; point-min. In that case, just parse from point-min assuming
|
||
;; a nil state.
|
||
(parse-partial-sexp (point-min) pos))))))
|
||
|
||
;; Debugging functions
|
||
|
||
(defun syntax-ppss-debug ()
|
||
(let ((pt nil)
|
||
(min-diffs nil))
|
||
(dolist (x (append (cdr (syntax-ppss--data)) (list (cons (point-min) nil))))
|
||
(when pt (push (- pt (car x)) min-diffs))
|
||
(setq pt (car x)))
|
||
min-diffs))
|
||
|
||
(provide 'syntax)
|
||
|
||
;;; syntax.el ends here
|