[RFC] Turn \[...\] constructs into full-fledged elements

[Nicolas Goaziou <mail@nicolasgoaziou.fr>]

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Hello,

I wasn't initially for such a change, but the more I think about it the
more I think it makes sense.

The point is to make \[...\] an element, which means that:

  - it cannot be inlined anymore, i.e., it has to start on a new line,
  - it cannot be filled anymore.

So basically, \[...\] will be closer to LaTeX definition.

WDYT?


Regards,

-- 
Nicolas Goaziou                                                0x80A93738

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From 8dba4429684684ce29ce2a984a075550313b7027 Mon Sep 17 00:00:00 2001
From: Nicolas Goaziou <mail@nicolasgoaziou.fr>
Date: Sat, 9 May 2015 11:29:48 +0200
Subject: [PATCH] Make \[...\] an element instead of an object

* lisp/org-element.el (org-element--set-regexps): Update regexp.
(org-element--latex-begin-environment):
(org-element--latex-end-environment): Remove variable.  Change it into
a function.
(org-element-latex-environment-parser):
(org-element-paragraph-parser): Use function.
(org-element-latex-fragment-parser): Remove \[...\] constructs.

* lisp/org.el (org-latex-regexps): Update regexp for \[...\].

* testing/lisp/test-org-element.el (test-org-element/latex-environment-parser):
  Add a test.
(test-org-element/latex-fragment-parser): Remove a test.

With this change \[...\] are considered elements and cannot be inlined
anymore.  As a consequence, they will not be filled anymore and stop
paragraphs.  However such inline constructs are no longer recognized.
---
 lisp/org-element.el              | 40 +++++++++++++++++++---------------------
 lisp/org.el                      |  2 +-
 testing/lisp/test-org-element.el | 12 +++++++-----
 3 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/lisp/org-element.el b/lisp/org-element.el
index 9037b37..31af3bc 100644
--- a/lisp/org-element.el
+++ b/lisp/org-element.el
@@ -172,7 +172,7 @@ specially in `org-element--object-lex'.")
 		;; Horizontal rules.
 		"-\\{5,\\}[ \t]*$" "\\|"
 		;; LaTeX environments.
-		"\\\\begin{\\([A-Za-z0-9*]+\\)}" "\\|"
+		"\\\\\\(begin{\\([A-Za-z0-9*]+\\)}\\|\\[\\)" "\\|"
 		;; Clock lines.
 		(regexp-quote org-clock-string) "\\|"
 		;; Lists.
@@ -2122,16 +2122,17 @@ CONTENTS is nil."
 ;;;; Latex Environment
 
 (defconst org-element--latex-begin-environment
-  "^[ \t]*\\\\begin{\\([A-Za-z0-9*]+\\)}"
+  "^[ \t]*\\\\\\(?:begin{\\([A-Za-z0-9*]+\\)}\\|\\[\\)"
   "Regexp matching the beginning of a LaTeX environment.
-The environment is captured by the first group.
+The environment is captured by the first group.  See also
+`org-element--latex-end-environment'.")
 
-See also `org-element--latex-end-environment'.")
-
-(defconst org-element--latex-end-environment
-  "\\\\end{%s}[ \t]*$"
-  "Format string matching the ending of a LaTeX environment.
-See also `org-element--latex-begin-environment'.")
+(defun org-element--latex-end-environment (environment)
+  "Build regexp matching the end of a LaTeX environment.
+See also `org-element--latex-begin-environment'."
+  (if environment
+      (format "\\\\end{%s}[ \t]*$" (regexp-quote environment))
+    "\\][ \t]*$"))
 
 (defun org-element-latex-environment-parser (limit affiliated)
   "Parse a LaTeX environment.
@@ -2150,9 +2151,8 @@ Assume point is at the beginning of the latex environment."
     (let ((case-fold-search t)
 	  (code-begin (point)))
       (looking-at org-element--latex-begin-environment)
-      (if (not (re-search-forward (format org-element--latex-end-environment
-					  (regexp-quote (match-string 1)))
-				  limit t))
+      (if (not (re-search-forward
+		(org-element--latex-end-environment (match-string 1)) limit t))
 	  ;; Incomplete latex environment: parse it as a paragraph.
 	  (org-element-paragraph-parser limit affiliated)
 	(let* ((code-end (progn (forward-line) (point)))
@@ -2254,8 +2254,7 @@ Assume point is at the beginning of the paragraph."
 		       ((looking-at org-element--latex-begin-environment)
 			(save-excursion
 			  (re-search-forward
-			   (format org-element--latex-end-environment
-				   (regexp-quote (match-string 1)))
+			   (org-element--latex-end-environment (match-string 1))
 			   limit t)))
 		       ((looking-at "[ \t]*#\\+\\(\\S-+\\)\\[.*\\]:")
 			(member-ignore-case (match-string 1)
@@ -2961,13 +2960,12 @@ Assume point is at the beginning of the LaTeX fragment."
 				    '(?\s ?\t ?\n ?, ?.)))
 			 (looking-at "\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|$\\)")
 			 (point)))
-		(case (char-after (1+ (point)))
-		  (?\( (search-forward "\\)" nil t))
-		  (?\[ (search-forward "\\]" nil t))
-		  (otherwise
-		   ;; Macro.
-		   (and (looking-at "\\\\[a-zA-Z]+\\*?\\(\\(\\[[^][\n{}]*\\]\\)\\|\\({[^{}\n]*}\\)\\)*")
-			(match-end 0))))))
+		(if (eq (char-after (1+ (point))) ?\()
+		    (search-forward "\\)" nil t)
+		  ;; Macro.
+		  (and (looking-at "\\\\[a-zA-Z]+\\*?\\(\\(\\[[^][\n{}]*\\]\\)\
+\\|\\({[^{}\n]*}\\)\\)*")
+		       (match-end 0)))))
 	     (post-blank (if (not after-fragment) (throw 'no-object nil)
 			   (goto-char after-fragment)
 			   (skip-chars-forward " \t")))
diff --git a/lisp/org.el b/lisp/org.el
index ac9d06d..1fbc8c9 100755
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -543,7 +543,7 @@ An entry can be toggled between COMMENT and normal with
     ("$1" "\\([^$]\\|^\\)\\(\\$[^ 	\r\n,;.$]\\$\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|$\\)" 2 nil)
     ("$"  "\\([^$]\\|^\\)\\(\\(\\$\\([^ 	\r\n,;.$][^$\n\r]*?\\(\n[^$\n\r]*?\\)\\{0,2\\}[^ 	\r\n,.$]\\)\\$\\)\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|$\\)" 2 nil)
     ("\\(" "\\\\([^\000]*?\\\\)" 0 nil)
-    ("\\[" "\\\\\\[[^\000]*?\\\\\\]" 0 nil)
+    ("\\[" "^[ \t]*\\\\\\[[^\000]*?\\\\\\][ \t]*$" 0 nil)
     ("$$" "\\$\\$[^\000]*?\\$\\$" 0 nil))
   "Regular expressions for matching embedded LaTeX.")
 
diff --git a/testing/lisp/test-org-element.el b/testing/lisp/test-org-element.el
index d7eb8e4..a0ac8e6 100644
--- a/testing/lisp/test-org-element.el
+++ b/testing/lisp/test-org-element.el
@@ -1375,9 +1375,15 @@ Paragraph"
 
 (ert-deftest test-org-element/latex-environment-parser ()
   "Test `latex-environment' parser."
+  ;; Standard test.
   (should
    (org-test-with-temp-text "\\begin{equation}\ne^{i\\pi}+1=0\n\\end{equation}"
      (org-element-map (org-element-parse-buffer) 'latex-environment 'identity)))
+  ;; Allow shorthand for "equation*" environment.
+  (should
+   (eq 'latex-environment
+       (org-test-with-temp-text "\\[e^{i\\pi}+1=0\n\\]"
+	 (org-element-type (org-element-at-point)))))
   ;; Allow nested environments.
   (should
    (equal
@@ -1420,7 +1426,7 @@ e^{i\\pi}+1=0
   (should-not
    (eq 'latex-environment
        (org-test-with-temp-text "\\begin{env*}{arg}something\\end{env}"
-				(org-element-type (org-element-at-point)))))
+	 (org-element-type (org-element-at-point)))))
   ;; LaTeX environments must be on separate lines.
   (should-not
    (eq 'latex-environment
@@ -1476,10 +1482,6 @@ e^{i\\pi}+1=0
    (eq 'latex-fragment
        (org-test-with-temp-text "\\(a\\)"
 	 (org-element-type (org-element-context)))))
-  (should
-   (eq 'latex-fragment
-       (org-test-with-temp-text "\\[a\\]"
-	 (org-element-type (org-element-context)))))
   ;; Test fragment at the beginning of an item.
   (should
    (eq 'latex-fragment
-- 
2.4.0