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[Emacs-diffs] master 52da972: Some generic support for multi-mode indent
From: |
Christoph Wedler |
Subject: |
[Emacs-diffs] master 52da972: Some generic support for multi-mode indentation. |
Date: |
Sun, 14 Jun 2015 14:48:23 +0000 |
branch: master
commit 52da972751d50c2bf27315c7cad96a185b5eb103
Author: Christoph Wedler <address@hidden>
Commit: Christoph Wedler <address@hidden>
Some generic support for multi-mode indentation.
* lisp/progmodes/prog-mode.el (prog-indentation-context): New
variable.
(prog-first-column, prog-widen): New convenience functions.
---
ChangeLog.2 | 7 ++++
lisp/progmodes/prog-mode.el | 66 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 73 insertions(+), 0 deletions(-)
diff --git a/ChangeLog.2 b/ChangeLog.2
index b8e1e38..5935503 100644
--- a/ChangeLog.2
+++ b/ChangeLog.2
@@ -1,3 +1,10 @@
+2015-06-14 Christoph Wedler <address@hidden>
+
+ Some generic support for multi-mode indentation.
+ * lisp/progmodes/prog-mode.el (prog-indentation-context): New
+ variable.
+ (prog-first-column, prog-widen): New convenience functions.
+
2015-06-13 Glenn Morris <address@hidden>
Tweaks for getting repository version; a bit more like it was for bzr.
diff --git a/lisp/progmodes/prog-mode.el b/lisp/progmodes/prog-mode.el
index 0d9fabd..cb8aaad 100644
--- a/lisp/progmodes/prog-mode.el
+++ b/lisp/progmodes/prog-mode.el
@@ -48,6 +48,51 @@
map)
"Keymap used for programming modes.")
+(defvar prog-indentation-context nil
+ "Non-nil while indenting embedded code chunks.
+There are languages where part of the code is actually written in
+a sub language, e.g., a Yacc/Bison or ANTLR grammar also consists
+of plain C code. This variable enables the major mode of the
+main language to use the indentation engine of the sub mode for
+lines in code chunks written in the sub language.
+
+When a major mode of such a main language decides to delegate the
+indentation of a line/region to the indentation engine of the sub
+mode, it is supposed to bind this variable to non-nil around the call.
+
+The non-nil value looks as follows
+ \(FIRST-COLUMN (START . END) PREVIOUS-CHUNKS)
+
+FIRST-COLUMN is the column the indentation engine of the sub mode
+should usually choose for top-level language constructs inside
+the code chunk (instead of 0).
+
+START to END is the region of the code chunk. See function
+`prog-widen' for additional info.
+
+PREVIOUS-CHUNKS, if non-nil, provides the indentation engine of
+the sub mode with the virtual context of the code chunk. Valid
+values are:
+
+ - A string containing code which the indentation engine can
+ consider as standing in front of the code chunk. To cache the
+ string's calculated syntactic information for repeated calls
+ with the same string, it is valid and expected for the inner
+ mode to add text-properties to the string.
+
+ A typical use case is for grammars with code chunks which are
+ to be indented like function bodies - the string would contain
+ a corresponding function header.
+
+ - A function called with the start position of the current
+ chunk. It will return either the region of the previous chunk
+ as \(PREV-START . PREV-END) or nil if there is no further
+ previous chunk.
+
+ A typical use case are literate programming sources - the
+ function would successively return the code chunks of the
+ previous macro definitions for the same name.")
+
(defun prog-indent-sexp (&optional defun)
"Indent the expression after point.
When interactively called with prefix, indent the enclosing defun
@@ -61,6 +106,27 @@ instead."
(end (progn (forward-sexp 1) (point))))
(indent-region start end nil))))
+(defun prog-first-column ()
+ "Return the indentation column normally used for top-level constructs."
+ (or (car prog-indentation-context) 0))
+
+(defun prog-widen ()
+ "Remove restrictions (narrowing) from current code chunk or buffer.
+This function can be used instead of `widen' in any function used
+by the indentation engine to make it respect the value
+`prog-indentation-context'.
+
+This function (like 'widen') is useful inside a
+`save-restriction' to make the indentation correctly work when
+narrowing is in effect."
+ (let ((chunk (cadr prog-indentation-context)))
+ (if chunk
+ ;; no widen necessary here, as narrow-to-region changes (not
+ ;; just narrows) existing restrictions
+ (narrow-to-region (car chunk) (or (cdr chunk) (point-max)))
+ (widen))))
+
+
(defvar-local prettify-symbols-alist nil
"Alist of symbol prettifications.
Each element looks like (SYMBOL . CHARACTER), where the symbol
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