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(elisp)User-Level Deletion

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User-Level Deletion Commands
============================

   This section describes higher-level commands for deleting text,
commands intended primarily for the user but useful also in Lisp
programs.

 - Command: delete-horizontal-space
     This function deletes all spaces and tabs around point.  It returns
     `nil'.

     In the following examples, we call `delete-horizontal-space' four
     times, once on each line, with point between the second and third
     characters on the line each time.

          ---------- Buffer: foo ----------
          I -!-thought
          I -!-     thought
          We-!- thought
          Yo-!-u thought
          ---------- Buffer: foo ----------
          
          (delete-horizontal-space)   ; Four times.
               => nil
          
          ---------- Buffer: foo ----------
          Ithought
          Ithought
          Wethought
          You thought
          ---------- Buffer: foo ----------

 - Command: delete-indentation &optional join-following-p
     This function joins the line point is on to the previous line,
     deleting any whitespace at the join and in some cases replacing it
     with one space.  If JOIN-FOLLOWING-P is non-`nil',
     `delete-indentation' joins this line to the following line
     instead.  The function returns `nil'.

     If there is a fill prefix, and the second of the lines being joined
     starts with the prefix, then `delete-indentation' deletes the fill
     prefix before joining the lines.  Note: Margins.

     In the example below, point is located on the line starting
     `events', and it makes no difference if there are trailing spaces
     in the preceding line.

          ---------- Buffer: foo ----------
          When in the course of human
          -!-    events, it becomes necessary
          ---------- Buffer: foo ----------
          
          (delete-indentation)
               => nil
          
          ---------- Buffer: foo ----------
          When in the course of human-!- events, it becomes necessary
          ---------- Buffer: foo ----------

     After the lines are joined, the function `fixup-whitespace' is
     responsible for deciding whether to leave a space at the junction.

 - Function: fixup-whitespace
     This function replaces all the whitespace surrounding point with
     either one space or no space, according to the context.  It
     returns `nil'.

     At the beginning or end of a line, the appropriate amount of space
     is none.  Before a character with close parenthesis syntax, or
     after a character with open parenthesis or expression-prefix
     syntax, no space is also appropriate.  Otherwise, one space is
     appropriate.  Note: Syntax Class Table.

     In the example below, `fixup-whitespace' is called the first time
     with point before the word `spaces' in the first line.  For the
     second invocation, point is directly after the `('.

          ---------- Buffer: foo ----------
          This has too many     -!-spaces
          This has too many spaces at the start of (-!-   this list)
          ---------- Buffer: foo ----------
          
          (fixup-whitespace)
               => nil
          (fixup-whitespace)
               => nil
          
          ---------- Buffer: foo ----------
          This has too many spaces
          This has too many spaces at the start of (this list)
          ---------- Buffer: foo ----------

 - Command: just-one-space
     This command replaces any spaces and tabs around point with a
     single space.  It returns `nil'.

 - Command: delete-blank-lines
     This function deletes blank lines surrounding point.  If point is
     on a blank line with one or more blank lines before or after it,
     then all but one of them are deleted.  If point is on an isolated
     blank line, then it is deleted.  If point is on a nonblank line,
     the command deletes all blank lines following it.

     A blank line is defined as a line containing only tabs and spaces.

     `delete-blank-lines' returns `nil'.