Mercurial > hg > xemacs-beta
diff man/xemacs/indent.texi @ 0:376386a54a3c r19-14
Import from CVS: tag r19-14
author | cvs |
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date | Mon, 13 Aug 2007 08:45:50 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/man/xemacs/indent.texi Mon Aug 13 08:45:50 2007 +0200 @@ -0,0 +1,187 @@ + +@node Indentation, Text, Major Modes, Top +@chapter Indentation +@cindex indentation + +@c WideCommands +@table @kbd +@item @key{TAB} +Indent current line ``appropriately'' in a mode-dependent fashion. +@item @key{LFD} +Perform @key{RET} followed by @key{TAB} (@code{newline-and-indent}). +@item M-^ +Merge two lines (@code{delete-indentation}). This would cancel out +the effect of @key{LFD}. +@item C-M-o +Split line at point; text on the line after point becomes a new line +indented to the same column that it now starts in (@code{split-line}). +@item M-m +Move (forward or back) to the first non-blank character on the current +line (@code{back-to-indentation}). +@item C-M-\ +Indent several lines to same column (@code{indent-region}). +@item C-x @key{TAB} +Shift block of lines rigidly right or left (@code{indent-rigidly}). +@item M-i +Indent from point to the next prespecified tab stop column +(@code{tab-to-tab-stop}). +@item M-x indent-relative +Indent from point to under an indentation point in the previous line. +@end table + +@kindex TAB +@cindex indentation + Most programming languages have some indentation convention. For Lisp +code, lines are indented according to their nesting in parentheses. The +same general idea is used for C code, though details differ. + + Use the @key{TAB} command to indent a line whatever the language. +Each major mode defines this command to perform indentation appropriate +for the particular language. In Lisp mode, @key{TAB} aligns a line +according to its depth in parentheses. No matter where in the line you +are when you type @key{TAB}, it aligns the line as a whole. In C mode, +@key{TAB} implements a subtle and sophisticated indentation style that +knows about many aspects of C syntax. + +@kindex TAB + In Text mode, @key{TAB} runs the command @code{tab-to-tab-stop}, which +indents to the next tab stop column. You can set the tab stops with +@kbd{M-x edit-tab-stops}. + +@menu +* Indentation Commands:: Various commands and techniques for indentation. +* Tab Stops:: You can set arbitrary "tab stops" and then + indent to the next tab stop when you want to. +* Just Spaces:: You can request indentation using just spaces. +@end menu + +@node Indentation Commands, Tab Stops, Indentation, Indentation +@section Indentation Commands and Techniques +@c ??? Explain what Emacs has instead of space-indent-flag. + + If you just want to insert a tab character in the buffer, you can type +@kbd{C-q @key{TAB}}. + +@kindex M-m +@findex back-to-indentation + To move over the indentation on a line, type @kbd{Meta-m} +(@code{back-to-indentation}). This command, given anywhere on a line, +positions point at the first non-blank character on the line. + + To insert an indented line before the current line, type @kbd{C-a C-o +@key{TAB}}. To make an indented line after the current line, use +@kbd{C-e @key{LFD}}. + +@kindex C-M-o +@findex split-line + @kbd{C-M-o} (@code{split-line}) moves the text from point to the end of +the line vertically down, so that the current line becomes two lines. +@kbd{C-M-o} first moves point forward over any spaces and tabs. Then it +inserts after point a newline and enough indentation to reach the same +column point is on. Point remains before the inserted newline; in this +regard, @kbd{C-M-o} resembles @kbd{C-o}. + +@kindex M-\ +@kindex M-^ +@findex delete-horizontal-space +@findex delete-indentation + To join two lines cleanly, use the @kbd{Meta-^} +(@code{delete-indentation}) command to delete the indentation at the +front of the current line, and the line boundary as well. Empty spaces +are replaced by a single space, or by no space if at the beginning of a +line, before a close parenthesis, or after an open parenthesis. +To delete just the indentation of a line, go to the beginning of the +line and use @kbd{Meta-\} (@code{delete-horizontal-space}), which +deletes all spaces and tabs around the cursor. + +@kindex C-M-\ +@kindex C-x TAB +@findex indent-region +@findex indent-rigidly + There are also commands for changing the indentation of several lines at +once. @kbd{Control-Meta-\} (@code{indent-region}) gives each line which +begins in the region the ``usual'' indentation by invoking @key{TAB} at the +beginning of the line. A numeric argument specifies the column to indent +to. Each line is shifted left or right so that its first non-blank +character appears in that column. @kbd{C-x @key{TAB}} +(@code{indent-rigidly}) moves all the lines in the region right by its +argument (left, for negative arguments). The whole group of lines moves +rigidly sideways, which is how the command gets its name.@refill + +@findex indent-relative + @kbd{M-x indent-relative} indents at point based on the previous line +(actually, the last non-empty line.) It inserts whitespace at point, moving +point, until it is underneath an indentation point in the previous line. +An indentation point is the end of a sequence of whitespace or the end of +the line. If point is farther right than any indentation point in the +previous line, the whitespace before point is deleted and the first +indentation point then applicable is used. If no indentation point is +applicable even then, @code{tab-to-tab-stop} is run (see next section). + + @code{indent-relative} is the definition of @key{TAB} in Indented Text +mode. @xref{Text}. + +@node Tab Stops, Just Spaces, Indentation Commands, Indentation +@section Tab Stops + +@kindex M-i +@findex tab-to-tab-stop + For typing in tables, you can use Text mode's definition of @key{TAB}, +@code{tab-to-tab-stop}. This command inserts indentation before point, +enough to reach the next tab stop column. Even if you are not in Text mode, +this function is associated with @kbd{M-i} anyway. + +@findex edit-tab-stops +@findex edit-tab-stops-note-changes +@kindex C-c C-c (Edit Tab Stops) +@vindex tab-stop-list + You can arbitrarily set the tab stops used by @kbd{M-i}. They are +stored as a list of column-numbers in increasing order in the variable +@code{tab-stop-list}. + + The convenient way to set the tab stops is using @kbd{M-x edit-tab-stops}, +which creates and selects a buffer containing a description of the tab stop +settings. You can edit this buffer to specify different tab stops, and +then type @kbd{C-c C-c} to make those new tab stops take effect. In the +tab stop buffer, @kbd{C-c C-c} runs the function +@code{edit-tab-stops-note-changes} rather than the default +@code{save-buffer}. @code{edit-tab-stops} records which buffer was current +when you invoked it, and stores the tab stops in that buffer. Normally +all buffers share the same tab stops and changing them in one buffer +affects all. If you make @code{tab-stop-list} local in one +buffer @code{edit-tab-stops} in that buffer edits only the local +settings. + + Below is the text representing ordinary tab stops every eight columns: + +@example + : : : : : : +0 1 2 3 4 +0123456789012345678901234567890123456789012345678 +To install changes, type C-c C-c +@end example + + The first line contains a colon at each tab stop. The remaining lines +help you see where the colons are and tell you what to do. + + Note that the tab stops that control @code{tab-to-tab-stop} have nothing +to do with displaying tab characters in the buffer. @xref{Display Vars}, +for more information on that. + +@node Just Spaces,, Tab Stops, Indentation +@section Tabs vs. Spaces + +@vindex indent-tabs-mode + Emacs normally uses both tabs and spaces to indent lines. If you prefer, +all indentation can be made from spaces only. To request this, set +@code{indent-tabs-mode} to @code{nil}. This is a per-buffer variable; +altering the variable affects only the current buffer, but there is a +default value which you can change as well. @xref{Locals}. + +@findex tabify +@findex untabify + There are also commands to convert tabs to spaces or vice versa, always +preserving the columns of all non-blank text. @kbd{M-x tabify} scans the +region for sequences of spaces, and converts sequences of at least three +spaces to tabs if that is possible without changing indentation. @kbd{M-x +untabify} changes all tabs in the region to corresponding numbers of spaces.