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Diffstat (limited to 'lispref/positions.texi')
| -rw-r--r-- | lispref/positions.texi | 84 |
1 files changed, 5 insertions, 79 deletions
diff --git a/lispref/positions.texi b/lispref/positions.texi index 6691a63c827..1032c85453b 100644 --- a/lispref/positions.texi +++ b/lispref/positions.texi @@ -37,9 +37,9 @@ to allow editing and insertion at different places. Like other positions, point designates a place between two characters (or before the first character, or after the last character), rather -than a particular character. Many terminals display the cursor over the -character that immediately follows point; on such terminals, point is -actually before the character on which the cursor sits. +than a particular character. Usually terminals display the cursor over +the character that immediately follows point; point is actually before +the character on which the cursor sits. @cindex point with narrowing The value of point is a number between 1 and the buffer size plus 1. @@ -119,8 +119,6 @@ or relative to the edges of the selected window. @xref{Point}. * Buffer End Motion:: Moving to the beginning or end of the buffer. * Text Lines:: Moving in terms of lines of text. * Screen Lines:: Moving in terms of lines as displayed. -* Vertical Motion:: Implementation of @code{next-line} and - @code{previous-line}. * List Motion:: Moving by parsing lists and sexps. * Skipping Characters:: Skipping characters belonging to a certain set. @end menu @@ -422,36 +420,6 @@ to use and more reliable (no dependence on goal column, etc.). @c ================ @end ignore -@defvar cache-long-line-scans -This variable determines whether Emacs should use caches to handle long -lines more quickly. This variable is buffer-local, in all buffers. - - Normally, the line-motion functions work by scanning the buffer for -newlines. Columnar operations (like @code{move-to-column} and -@code{compute-motion}) also work by scanning the buffer, summing -character widths as they go. This works well for ordinary text, but if -the buffer's lines are very long (say, more than 500 characters), these -motion functions will take longer to execute. Emacs may also take -longer to update the display. - - If @code{cache-long-line-scans} is non-@code{nil}, these motion -functions cache the results of their scans, and consult the cache to -avoid rescanning regions of the buffer until the text is modified. The -caches are most beneficial when they prevent the most searching---that -is, when the buffer contains long lines and large regions of characters -with the same, fixed screen width. - - When @code{cache-long-line-scans} is non-@code{nil}, processing short -lines will become slightly slower (because of the overhead of consulting -the cache), and the caches will use memory roughly proportional to the -number of newlines and characters whose screen width varies. - - The caches require no explicit maintenance; their accuracy is -maintained internally by the Emacs primitives. Enabling or disabling -the cache should not affect the behavior of any of the motion functions; -it should only affect their performance. -@end defvar - Also see the functions @code{bolp} and @code{eolp} in @ref{Near Point}. These functions do not move point, but test whether it is already at the beginning or end of a line. @@ -532,7 +500,8 @@ the form @code{(@var{hpos} . @var{vpos})}. The argument @var{width} is the number of columns available to display text; this affects handling of continuation lines. Use the value -returned by @code{window-width} for the window of your choice. +returned by @code{window-width} for the window of your choice; +normally, use @code{(window-width @var{window})}. The argument @var{offsets} is either @code{nil} or a cons cell of the form @code{(@var{hscroll} . @var{tab-offset})}. Here @var{hscroll} is @@ -585,49 +554,6 @@ When you use @code{compute-motion} for the minibuffer, you need to use beginning of the first screen line. @xref{Minibuffer Misc}. @end defun -@node Vertical Motion -@comment node-name, next, previous, up -@subsection The User-Level Vertical Motion Commands -@cindex goal column -@cindex vertical text line motion -@findex next-line -@findex previous-line - - A goal column is useful if you want to edit text such as a table in -which you want to move point to a certain column on each line. The goal -column affects the vertical text line motion commands, @code{next-line} -and @code{previous-line}. @xref{Basic,, Basic Editing Commands, emacs, -The GNU Emacs Manual}. - -@defopt goal-column -This variable holds an explicitly specified goal column for vertical -line motion commands. If it is an integer, it specifies a column, and -these commands try to move to that column on each line. If it is -@code{nil}, then the commands set their own goal columns. Any other -value is invalid. -@end defopt - -@defvar temporary-goal-column -This variable holds the temporary goal column during a sequence of -consecutive vertical line motion commands. It is overridden by -@code{goal-column} if that is non-@code{nil}. It is set each time a -vertical motion command is invoked, unless the previous command was also -a vertical motion command. -@end defvar - -@defopt track-eol -This variable controls how the vertical line motion commands operate -when starting at the end of a line. If @code{track-eol} is -non-@code{nil}, then vertical motion starting at the end of a line will -keep to the ends of lines (instead of keeping to a particular column). -This means moving to the end of each line moved onto. The value of -@code{track-eol} has no effect if point is not at the end of a line when -the first vertical motion command is given. - -@code{track-eol} has its effect by telling line motion commands to set -@code{temporary-goal-column} to 9999 instead of to the current column. -@end defopt - @node List Motion @comment node-name, next, previous, up @subsection Moving over Balanced Expressions |