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5.6.5 Automatic Extraction of New Things

The automatic TeX information extractor works by searching for regular expressions in the TeX files, and storing the matched information. You can add support for new constructs to the parser, something that is needed when you add new commands to define symbols.

For example, in the file ‘macro.tex’ I define the following macro.


AUCTeX will automatically figure out that ‘newmacro’ is a macro that takes five arguments. However, it is not smart enough to automatically see that each time we use the macro, two new macros are defined. We can specify this information in a style hook file.

;;; macro.el --- Special code for my own macro file.

;;; Code:

(defvar TeX-newmacro-regexp
    (1 2) TeX-auto-multi)
  "Matches \newmacro definitions.")

(defvar TeX-auto-multi nil
  "Temporary for parsing \\newmacro definitions.")

(defun TeX-macro-cleanup ()
  "Move symbols from `TeX-auto-multi' to `TeX-auto-symbol'."
  (mapcar (lambda (list)
	    (mapcar (lambda (symbol)
		      (setq TeX-auto-symbol
			    (cons symbol TeX-auto-symbol)))

(defun TeX-macro-prepare ()
  "Clear `Tex-auto-multi' before use."
  (setq TeX-auto-multi nil))

(add-hook 'TeX-auto-prepare-hook 'TeX-macro-prepare)
(add-hook 'TeX-auto-cleanup-hook 'TeX-macro-cleanup)

 (lambda ()
   (TeX-auto-add-regexp TeX-newmacro-regexp)
   (TeX-add-symbols '("newmacro"
		      (TeX-arg-macro "Capitalized macro: \\")
		      "BibTeX entry: "

;;; macro.el ends here

When this file is first loaded, it adds a new entry to TeX-newmacro-regexp, and defines a function to be called before the parsing starts, and one to be called after the parsing is done. It also declares a variable to contain the data collected during parsing. Finally, it adds a style hook which describes the ‘newmacro’ macro, as we have seen it before.

So the general strategy is: Add a new entry to TeX-newmacro-regexp. Declare a variable to contain intermediate data during parsing. Add hook to be called before and after parsing. In this case, the hook before parsing just initializes the variable, and the hook after parsing collects the data from the variable, and adds them to the list of symbols found.

Variable: TeX-auto-regexp-list

List of regular expressions matching TeX macro definitions.

The list has the following format ((REGEXP MATCH TABLE) …), that is, each entry is a list with three elements.

REGEXP. Regular expression matching the macro we want to parse.

MATCH. A number or list of numbers, each representing one parenthesized subexpression matched by REGEXP.

TABLE. The symbol table to store the data. This can be a function, in which case the function is called with the argument MATCH. Use TeX-match-buffer to get match data. If it is not a function, it is presumed to be the name of a variable containing a list of match data. The matched data (a string if MATCH is a number, a list of strings if MATCH is a list of numbers) is put in front of the table.

Variable: TeX-auto-prepare-hook nil

List of functions to be called before parsing a TeX file.

Variable: TeX-auto-cleanup-hook nil

List of functions to be called after parsing a TeX file.

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This document was generated by Mosè Giordano on October 29, 2014 using texi2html 1.82.