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3.2 Folding Macros and Environments

A popular complaint about markup languages like TeX and LaTeX is that there is too much clutter in the source text and that one cannot focus well on the content. There are macros where you are only interested in the content they are enclosing, like font specifiers where the content might already be fontified in a special way by font locking. Or macros the content of which you only want to see when actually editing it, like footnotes or citations. Similarly you might find certain environments or comments distracting when trying to concentrate on the body of your document.

With AUCTeX’s folding functionality you can collapse those items and replace them by a fixed string, the content of one of their arguments, or a mixture of both. If you want to make the original text visible again in order to view or edit it, move point sideways onto the placeholder (also called display string) or left-click with the mouse pointer on it. The macro or environment will unfold automatically, stay open as long as point is inside of it and collapse again once you move point out of it. (Note that folding of environments currently does not work in every AUCTeX mode.)

In order to use this feature, you have to activate TeX-fold-mode which will activate the auto-reveal feature and the necessary commands to hide and show macros and environments. You can activate the mode in a certain buffer by typing the command M-x TeX-fold-mode <RET> or using the keyboard shortcut C-c C-o C-f. If you want to use it every time you edit a LaTeX document, add it to a hook:

(add-hook 'LaTeX-mode-hook (lambda ()
                             (TeX-fold-mode 1)))

If it should be activated in all AUCTeX modes, use TeX-mode-hook instead of LaTeX-mode-hook.

Once the mode is active there are several commands available to hide and show macros, environments and comments:

Command: TeX-fold-buffer

(C-c C-o C-b) Hide all foldable items in the current buffer according to the setting of TeX-fold-type-list.

If you want to have this done automatically every time you open a file, add it to a hook and make sure the function is called after font locking is set up for the buffer. The following code should accomplish this:

(add-hook 'find-file-hook #'TeX-fold-buffer t)

The command can be used any time to refresh the whole buffer and fold any new macros and environments which were inserted after the last invocation of the command.

User Option: TeX-fold-type-list

List of symbols determining the item classes to consider for folding. This can be macros, environments and comments. Per default only macros and environments are folded.

User Option: TeX-fold-force-fontify

In order for all folded content to get the right faces, the whole buffer has to be fontified before folding is carried out. TeX-fold-buffer therefore will force fontification of unfontified regions. As this will prolong the time folding takes, you can prevent forced fontification by customizing the variable TeX-fold-force-fontify.

User Option: TeX-fold-auto

By default, a macro inserted with TeX-insert-macro (C-c C-m) will not be folded. Set this variable to a non-nil value to aumatically fold macros as soon as they are inserted.

User Option: TeX-fold-preserve-comments

By default items found in comments will be folded. If your comments often contain unfinished code this might lead to problems. Give this variable a non-nil value and foldable items in your comments will be left alone.

User Option: TeX-fold-unfold-around-mark

When this variable is non-nil and there is an active regione, text around the mark will be kept unfolded.

Command: TeX-fold-region

(C-c C-o C-r) Hide all configured macros in the marked region.

Command: TeX-fold-paragraph

(C-c C-o C-p) Hide all configured macros in the paragraph containing point.

Command: TeX-fold-macro

(C-c C-o C-m) Hide the macro on which point currently is located. If the name of the macro is found in TeX-fold-macro-spec-list, the respective display string will be shown instead. If it is not found, the name of the macro in sqare brackets or the default string for unspecified macros (TeX-fold-unspec-macro-display-string) will be shown, depending on the value of the variable TeX-fold-unspec-use-name.

Command: TeX-fold-env

(C-c C-o C-e) Hide the environment on which point currently is located. The behavior regarding the display string is analogous to TeX-fold-macro and determined by the variables TeX-fold-env-spec-list and TeX-fold-unspec-env-display-string respectively.

Command: TeX-fold-math

Hide the math macro on which point currently is located. If the name of the macro is found in TeX-fold-math-spec-list, the respective display string will be shown instead. If it is not found, the name of the macro in sqare brackets or the default string for unspecified macros (TeX-fold-unspec-macro-display-string) will be shown, depending on the value of the variable TeX-fold-unspec-use-name.

Command: TeX-fold-comment

(C-c C-o C-c) Hide the comment point is located on.

Command: TeX-fold-clearout-buffer

(C-c C-o b) Permanently unfold all macros and environments in the current buffer.

Command: TeX-fold-clearout-region

(C-c C-o r) Permanently unfold all macros and environments in the marked region.

Command: TeX-fold-clearout-paragraph

(C-c C-o p) Permanently unfold all macros and environments in the paragraph containing point.

Command: TeX-fold-clearout-item

(C-c C-o i) Permanently show the macro or environment on which point currently is located. In contrast to temporarily opening the macro when point is moved sideways onto it, the macro will be permanently unfolded and will not collapse again once point is leaving it.

Command: TeX-fold-dwim

(C-c C-o C-o) Hide or show items according to the current context. If there is folded content, unfold it. If there is a marked region, fold all configured content in this region. If there is no folded content but a macro or environment, fold it.

In case you want to use a different prefix than C-c C-o for these commands you can customize the variable TeX-fold-command-prefix. (Note that this will not change the key binding for activating the mode.)

The commands above will only take macros or environments into consideration which are specified in the variables TeX-fold-macro-spec-list or TeX-fold-env-spec-list respectively.

User Option: TeX-fold-macro-spec-list

List of replacement specifiers and macros to fold. The specifier can be a string, an integer or a function symbol.

If you specify a string, it will be used as a display replacement for the whole macro. Numbers in braces, brackets, parens or angle brackets will be replaced by the respective macro argument. For example ‘{1}’ will be replaced by the first mandatory argument of the macro. One can also define alternatives within the specifier which are used if an argument is not found. Alternatives are separated by ‘||’. They are most useful with optional arguments. As an example, the default specifier for ‘\item’ is ‘[1]:||*’ which means that if there is an optional argument, its value is shown followed by a colon. If there is no optional argument, only an asterisk is used as the display string.

If you specify a number as the first element, the content of the respective mandatory argument of a LaTeX macro will be used as the placeholder.

If the first element is a function symbol, the function will be called with all mandatory arguments of the macro and the result of the function call will be used as a replacement for the macro. Such functions typically return a string, but may also return the symbol abort to indicate that the macro should not be folded.

The placeholder is made by copying the text from the buffer together with its properties, i.e. its face as well. If fontification has not happened when this is done (e.g. because of lazy font locking) the intended fontification will not show up. As a workaround you can leave Emacs idle a few seconds and wait for stealth font locking to finish before you fold the buffer. Or you just re-fold the buffer with TeX-fold-buffer when you notice a wrong fontification.

User Option: TeX-fold-env-spec-list

List of display strings or argument numbers and environments to fold. Argument numbers refer to the ‘\begin’ statement. That means if you have e.g. ‘\begin{tabularx}{\linewidth}{XXX} ... \end{tabularx}’ and specify 3 as the argument number, the resulting display string will be “XXX”.

User Option: TeX-fold-math-spec-list

List of display strings and math macros to fold.

The variables TeX-fold-macro-spec-list, TeX-fold-env-spec-list, and TeX-fold-math-spec-list apply to any AUCTeX mode. If you want to make settings which are only applied to LaTeX mode, you can use the mode-specific variables LaTeX-fold-macro-spec-list, LaTeX-fold-env-spec-list, and LaTeX-fold-math-spec-list

User Option: TeX-fold-unspec-macro-display-string

Default display string for macros which are not specified in TeX-fold-macro-spec-list.

User Option: TeX-fold-unspec-env-display-string

Default display string for environments which are not specified in TeX-fold-env-spec-list.

User Option: TeX-fold-unspec-use-name

If non-nil the name of the macro or environment surrounded by square brackets is used as display string, otherwise the defaults specified in TeX-fold-unspec-macro-display-string or TeX-fold-unspec-env-display-string respectively.

When you hover with the mouse pointer over folded content, its original text will be shown in a tooltip or the echo area depending on Tooltip mode being activate. In order to avoid exorbitantly big tooltips and to cater for the limited space in the echo area the content will be cropped after a certain amount of characters defined by the variable TeX-fold-help-echo-max-length.

User Option: TeX-fold-help-echo-max-length

Maximum length of original text displayed in a tooltip or the echo area for folded content. Set it to zero in order to disable this feature.

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