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This is Info file elisp, produced by Makeinfo-1.47 from the input file elisp.texi. This file documents GNU Emacs Lisp. This is edition 1.03 of the GNU Emacs Lisp Reference Manual, for Emacs Version 18. Published by the Free Software Foundation, 675 Massachusetts Avenue, Cambridge, MA 02139 USA Copyright (C) 1990 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. File: elisp, Node: Deletion, Next: User-Level Deletion, Prev: Commands for Insertion, Up: Text Deletion of Text ================ All of the deletion functions operate on the current buffer, and all return a value of `nil'. In addition to these functions, you can also delete text using the "kill" functions that save it in the kill ring for the user; some of these functions save text in the kill ring in some cases but not in the usual case. *Note The Kill Ring::. -- Function: erase-buffer This function deletes the entire text of the current buffer, leaving it empty. If the buffer is read-only, it signals a `buffer-read-only' error. Otherwise the text is deleted with no confirmation required. The value is always `nil'. As a safety measure, this function is not interactively callable. -- Command: delete-region START END This function deletes the text in the current buffer in the region defined by START and END. The value is `nil'. -- Command: delete-char COUNT &optional KILLP This function deletes COUNT characters directly after point, or before point if COUNT is negative. If KILLP is non-`nil', then it saves the deleted characters in the kill ring. In an interactive call, COUNT is the numeric prefix argument, and KILLP is the unprocessed prefix argument. Therefore, if a prefix argument is supplied, the text is saved in the kill ring. If no prefix argument is supplied, then one character is deleted, but not saved in the kill ring. The value returned is always `nil'. -- Command: delete-backward-char COUNT &optional KILLP This function deletes COUNT characters directly before point, or after point if COUNT is negative. If KILLP is non-`nil', then it saves the deleted characters in the kill ring. In an interactive call, COUNT is the numeric prefix argument, and KILLP is the unprocessed prefix argument. Therefore, if a prefix argument is supplied, the text is saved in the kill ring. If no prefix argument is supplied, then one character is deleted, but not saved in the kill ring. The value returned is always `nil'. -- Command: backward-delete-char-untabify COUNT &optional KILLP This function deletes COUNT characters backward, changing tabs into spaces. When the next character to be deleted is a tab, it is first replaced with the proper number of spaces to preserve alignment and then one of those spaces is deleted instead of the tab. If KILLP is non-`nil', then the command saves the deleted characters in the kill ring. If COUNT is negative, then tabs are not changed to spaces, and the characters are deleted by calling `delete-backward-char' with COUNT. In an interactive call, COUNT is the numeric prefix argument, and KILLP is the unprocessed prefix argument. Therefore, if a prefix argument is supplied, the text is saved in the kill ring. If no prefix argument is supplied, then one character is deleted, but not saved in the kill ring. The value returned is always `nil'. File: elisp, Node: User-Level Deletion, Next: The Kill Ring, Prev: Deletion, Up: Text 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, assume that `delete-horizontal-space' is called four times, once on each line, with point between the second and third characters on the line. ---------- 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 following line instead. The value is `nil'. 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 white space between the objects on either side of point with either one space or no space as appropriate. It returns `nil'. The appropriate amount of space is none at the beginning or end of the line. Otherwise, it is one space except when point is before a character with close parenthesis syntax or after a character with open parenthesis or expression-prefix syntax. *Note Syntax Class Table::. In the example below, point is at the beginning of the second line when `fixup-whitespace' is called the first time. It is located directly after the `(' for the second invocation. ---------- Buffer: foo ---------- This has too many spaces -!- at the front of this line 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 at the front of this line 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'. File: elisp, Node: The Kill Ring, Next: Undo, Prev: User-Level Deletion, Up: Text The Kill Ring ============= "Kill" functions delete text like the deletion functions, but save it so that the user can reinsert it by "yanking". Most of these functions have `kill-' in their name. By contrast, the functions whose names start with `delete-' normally do not save text for yanking (though they can still be undone); these are "deletion" functions. Most of the kill commands are primarily for interactive use, and are not described here. What we do describe are the functions provided for use in writing such commands. When deleting text for internal purposes within a Lisp function, you should normally use deletion functions, so as not to disturb the kill ring contents. *Note Deletion::. Emacs saves the last several batches of killed text in a list. We call it the "kill ring" because, in yanking, the elements are considered to be in a cyclic order. The list is kept in the variable `kill-ring', and can be operated on with the usual functions for lists; there are also specialized functions, described in this section, which treat it as a ring. Some people think use of the word "kill" in Emacs is unfortunate, since it refers to processes which specifically *do not* destroy the entities "killed". This is in sharp contrast to ordinary life, in which death is permanent and "killed" entities do not come back to life. Therefore, other metaphors have been proposed. For example, the term "cut ring" makes sense to people who, in pre-computer days, used scissors and paste to cut up and rearrange manuscripts. However, it would be difficult to change now. * Menu: * Data in Kill Ring:: What text looks like in the kill ring. * Kill Functions:: Functions that kill text. * Yank Commands:: Commands that access the kill ring. * Kill Ring Internals:: Variables that hold kill-ring data. File: elisp, Node: Data in Kill Ring, Next: Kill Functions, Prev: The Kill Ring, Up: The Kill Ring Data Structures in the Kill Ring -------------------------------- Killed text is kept as strings in a list. A short kill ring, for example, might look like this: ("some text" "a different piece of text" "yet more text") Functions that push more text into the list make the text in question into a string (using `buffer-substring'), add the string to the front of the list, and then look at the length of the list. If the length is longer than the value of `kill-ring-max', the last entry in the list is dropped off when the new entry is put on. The `kill-ring-yank-pointer' global variable points to the kill ring entry that a "yank" function will copy. Several functions move this pointer from one entry to another, and a user can thereby specify which entry to copy. Here is a diagram that shows the variable `kill-ring-yank-pointer' pointing to the second entry in the kill ring `("some text" "a different piece of text" "yet more text")'. kill-ring kill-ring-yank-pointer | | | ___ ___ ---> ___ ___ ___ ___ --> |___|___|------> |___|___|--> |___|___|--> nil | | | | | | | | -->"yet more text" | | | --> "a different piece of text" | --> "some text" (This circumstance occurs after `C-y' (`yank') is immediately followed by `M-y' (`yank-pop').) Both `kill-ring' and `kill-ring-yank-pointer' are Lisp variables whose values are normally lists. The word "pointer" in the name of the `kill-ring-yank-pointer' indicates that the variable's purpose is to identify one element of the list that will be used by default by the next yank command. The value of `kill-ring-yank-pointer' is always `eq' to one of the links in the kill ring list. The element it identifies is the CAR of that link. Moving `kill-ring-yank-pointer' to a different link is called "rotating the kill ring". The functions that do this treat the kill ring (which is a list) as ring; that is to say, a change that would otherwise move the pointer past the end of the list (which would be useless) instead moves the pointer to the first link on the list. Likewise, moving back from the first link goes to the last one. `kill-region' is the primitive method of killing text. Any command that calls this function is a "kill command" (and should probably have the word "kill" in its name). `kill-region' puts the newly killed text in a new element at the beginning of the `kill-ring' list, and then sets `kill-ring-yank-pointer' to point to the first link of the list, which contains the first element. Consequently, the next `yank' command will yank the text just killed. In this situation, `kill-ring' and `kill-ring-yank-pointer' are `eq' to each other. When kill commands are interwoven with other commands, the killed portions of text are put into separate entries in the kill ring. But when two or more kill commands are executed in sequence, the text killed by the second (or third, etc.) kill command is appended to the text killed by the first command so as to make one entry in the kill ring. The `kill-region' function uses the `last-command' variable to keep track of whether the previous was a kill command, and in such cases appends the killed text to the most recent entry. File: elisp, Node: Kill Functions, Next: Yank Commands, Prev: Data in Kill Ring, Up: The Kill Ring Functions for Killing --------------------- -- Command: kill-region START END This function kills the text in the region defined by START and END. The text is deleted but saved in the kill ring. The value is always `nil'. In an interactive call, START and END are point and the mark. -- Command: kill-line &optional COUNT This function kills the rest of the line following point, not including the newline. If point is directly before a newline, or if there is only whitespace between point and the newline, then it kills the whitespace and newline. If COUNT is supplied, then the command kills that many lines (*including* the newline). (This makes executing `(kill-line 2)' different from executing `(kill-line)' twice.) If COUNT is negative, then `kill-line' kills lines backwards. In an interactive call, COUNT is the raw prefix argument (which then gets converted to a number if non-`nil'). The value is always `nil'. -- Command: zap-to-char COUNT CHARACTER In Emacs version 18, this function kills the text from point up to *but not including* the specified character. Thus, if the cursor is at the beginning of this sentence and the character is `s', `Thu' is deleted. If the argument is 2, `Thus, if the cur' is deleted, up to but not including the `s' in `cursor'. In Emacs version 19, this function will kill all text in the region from point up to and including the next COUNT occurrences of CHARACTER. Thus, in the example shown in the previous paragraph, the terminating `s' *will* be removed. The version 18 implementation kills text to the end of the buffer if the specified character is not found, but the version 19 implementation will simply signal an error. The function scans backward from point if COUNT is negative. The value is always `nil'. -- Command: copy-region-as-kill START END This function saves the region defined by START and END on the kill ring, but does not delete the text from the buffer. It returns `nil'. In an interactive call, START and END are point and the mark. File: elisp, Node: Yank Commands, Next: Kill Ring Internals, Prev: Kill Functions, Up: The Kill Ring Functions for Yanking --------------------- -- Command: yank &optional ARG This function inserts the text in the first entry in the kill ring directly before point. After the yank, the mark is positioned at the beginning and point is positioned after the end of the inserted text. If ARG is a list (which occurs interactively when the user types `C-u' with no digits), then `yank' inserts the text as described above, but puts point before the yanked text and puts the mark after it. If ARG is a number, then `yank' inserts the ARGth most recently killed text. `yank' does not alter the contents of the kill ring or rotate it. It returns `nil'. -- Command: yank-pop ARG This function replaces the just-yanked text with another batch of killed text--another element of the kill ring. This command is allowed only immediately after a `yank' or a `yank-pop'. At such a time, the region contains text that was just inserted by the previous `yank'. `yank-pop' deletes that text and inserts in its place a different stretch of killed text. The text that is deleted is not inserted into the kill ring, since it is already in the kill ring somewhere. If ARG is `nil', then the existing region contents are replaced with the previous element of the kill ring. If ARG is numeric, then the ARG'TH previous kill is the replacement. If ARG is negative, a more recent kill is the replacement. The sequence of kills in the kill ring wraps around, so that after the oldest one comes the newest one, and before the newest one goes the oldest. The value is always `nil'. File: elisp, Node: Kill Ring Internals, Prev: Yank Commands, Up: The Kill Ring Internals of the Kill Ring -------------------------- This section describes the lower levels of the kill ring. -- Variable: kill-ring List of killed text sequences, most recently killed first. -- Variable: kill-ring-yank-pointer This variable's value indicates which element of the kill ring is the "front" of the ring. More precisely, the value is a sublist of the value of `kill-ring', and its CAR is the kill string at the front of the ring. Rotating the ring works by changing `kill-ring-yank-pointer', and does not actually change the value of `kill-ring'. Commands which do change the kill ring also copy the new kill ring value into this variable. The effect is to rotate the ring so that the newly killed text is at front. -- Command: rotate-yank-pointer COUNT This function rotates the kill ring COUNT positions, which means setting `kill-ring-yank-pointer' to some other link in the kill ring list. It returns the new value of `kill-ring-yank-pointer'. -- User Option: kill-ring-max The value of this variable is the maximum length to which the kill ring can grow, before elements are thrown away on a first-in, first-out basis. The default value for `kill-ring-max' is 30. File: elisp, Node: Undo, Next: Filling, Prev: The Kill Ring, Up: Text Most buffers have an "undo stack" which records all changes made to the buffer's text so that they can be undone. (In general, all buffers have undo stacks except special-purpose buffers for which Emacs assumes that undoing is not useful.) The size of an undo stack is limited, so large changes or a large number of changes cannot be undone. Undoing an old change is itself a change, and is added to the undo stack. However, you are not limited to undoing just the single most recent change; you can keep undoing older and older changes, even as the undo's themselves are being added to the stack. -- Command: undo &optional ARG This is a user-level command to undo some previous changes. It uses `undo-more' and `undo-start'. By repeating this command you can undo earlier and earlier changes, until the information in the undo stack is used up. A numeric argument serves as a repeat count. The value is unpredictable. -- Function: undo-boundary This function places a boundary between units of undo. The undo command stops at such a boundary, and successive undo commands will undo to earlier and earlier boundaries. The return value is `nil'. The editor command loop automatically creates an undo boundary between keystroke commands. Thus, each undo normally undoes the effects of one command. Calling this function explicitly is useful for splitting the effects of a command into more than one unit. For example, `query-replace' calls this function after each replacement so that the user can undo individual replacements one by one. -- Function: undo-more COUNT This function is used to undo COUNT additional units of undo. It is not safe if the buffer has been changed in any fashion other than undo since the last call to `undo-start'. Multiple calls to `undo-more' have a cumulative effect, undoing farther back in time. The return value is `nil'. -- Function: undo-start This function prepares to undo one or more units of undo describing the most recent changes to the current buffer. It does not actually undo anything (or change the buffer at all); only `undo-more' does that. It returns `nil'. One use of this function is to break a sequence of undo's, so a subsequent call to `undo-more' will undo the recent run of undoing, rather than extend it into the past. The command `undo' calls `undo-start' whenever the previous command was not an `undo'. -- Command: buffer-enable-undo &optional BUFFER-OR-NAME This function assigns an undo stack for buffer BUFFER-OR-NAME, so that subsequent changes can be undone. If no argument is supplied, then the current buffer is used. If the buffer already has an undo stack, nothing is changed. This function returns `nil'. In an interactive call, BUFFER-OR-NAME is the current buffer. You cannot specify any other buffer. -- Function: buffer-flush-undo BUFFER This function deassigns the undo stack of the buffer BUFFER, so that it will not take up space. As a result, it is no longer possible to undo either previous changes or any subsequent changes. If the buffer already has no undo stack, then this function has no effect. This function returns `nil'. It cannot be called interactively. File: elisp, Node: Filling, Next: Auto Filling, Prev: Undo, Up: Text Filling ======= "Filling" means adjusting the lengths of lines (by moving words between them) so that they are nearly (but no greater than) a specified maximum width. Additionally, lines can be "justified", which means that spaces are inserted between words to make the line exactly the specified width. The width is controlled by the variable `fill-column'. For ease of reading, lines should be no longer than 70 or so columns. You can use Auto Fill mode (*note Auto Filling::.) to fill text automatically as you insert it, but changes to existing text may leave it improperly filled. Then you must fill the text explicitly. Most of the functions in this section return values that are not meaningful. -- Command: fill-paragraph JUSTIFY-FLAG This function fills the paragraph at or after point. If JUSTIFY-FLAG is non-`nil', each line is justified as well. -- Command: fill-region START END &optional JUSTIFY-FLAG This function fills each of the paragraphs in the region from start to end. It justifies as well if JUSTIFY-FLAG is non-`nil'. (In an interactive call, this is true if there is a prefix argument.) The variable `paragraph-separate' controls how to distinguish paragraphs. -- Command: fill-individual-paragraphs START END &optional JUSTIFY-FLAG MAIL-FLAG This function fills each paragraph in the region according to its individual fill prefix. Thus, if the lines of a paragraph are indented with spaces, the filled paragraph will continue to be indented in the same fashion. The first two arguments, START and END, are the beginning and end of the region that will be filled. The third and fourth arguments, JUSTIFY-FLAG and MAIL-FLAG, are optional. If JUSTIFY-FLAG is non-`nil', the paragraphs are justified as well as filled. If MAIL-FLAG is non-`nil', the function is told that it is operating on a mail message and therefore should not fill the header lines. -- Command: fill-region-as-paragraph START END &optional JUSTIFY-FLAG This function considers a region of text as a paragraph and fills it. If the region was made up of many paragraphs, the blank lines between paragraphs are removed. This function justifies as well as filling when JUSTIFY-FLAG is non-`nil'. In an interactive call, any prefix argument requests justification. -- Command: justify-current-line This function inserts spaces between the words of the current line so that the line ends exactly at `fill-column'. It returns `nil'. -- User Option: fill-column This buffer-local variable specifies the maximum width of filled lines. Its value should be an integer, which is a number of columns. All the filling, justification and centering commands are affected by this variable, including Auto Fill mode (*note Auto Filling::.). As a practical matter, if you are writing text for other people to read, you should set `fill-column' to no more than 70. Otherwise the line will be too long for people to read comfortably, and this can make the text seem clumsy. -- Variable: default-fill-column The value of this variable is the default value for `fill-column' in buffers that do not override it. This is the same as `(default-value 'fill-column)'. The default value for `default-fill-column' is 70. File: elisp, Node: Auto Filling, Next: Sorting, Prev: Filling, Up: Text Auto Filling ============ "Filling" breaks text into lines that are no more than a specified number of columns wide. Filled lines end between words, and therefore may have to be shorter than the maximum width. Auto Fill mode is a minor mode in which Emacs fills lines automatically as text as inserted. This section describes the hook and the two variables used by Auto Fill mode. For a description of functions that you can call manually to fill and justify text, see *Note Filling::. -- Variable: auto-fill-hook The value of this variable should be a function (of no arguments) to be called after self-inserting a space at a column beyond `fill-column'. It may be `nil', in which case nothing special is done. The default value for `auto-fill-hook' is `do-auto-fill', a function whose sole purpose is to implement the usual strategy for breaking a line. Since `auto-fill-hook' is not called by the `run-hooks' function, it will be renamed `auto-fill-function' in Version 19. File: elisp, Node: Sorting, Next: Indentation, Prev: Auto Filling, Up: Text Sorting Text ============ The sorting commands described in this section all rearrange text in a buffer. This is in contrast to the function `sort', which rearranges the order of the elements of a list (*note Rearrangement::.). The values returned by these commands are not meaningful. -- Command: sort-regexp-fields REVERSE RECORD-REGEXP KEY-REGEXP START END This command sorts the region between START and END alphabetically as specified by RECORD-REGEXP and KEY-REGEXP. If REVERSE is a negative integer, then sorting is in reverse order. Alphabetical sorting means that two sort keys are compared by comparing the first characters of each, the second characters of each, and so on. If a mismatch is found, it means that the sort keys are unequal; the sort key whose character is less at the point of first mismatch is the lesser sort key. The individual characters are compared according to their numerical values. Since Emacs uses the ASCII character set, the ordering in that set determines alphabetical order. The value of the RECORD-REGEXP argument specifies the textual units or "records" that should be sorted. At the end of each record, a search is done for this regular expression, and the text that matches it is the next record. For example, the regular expression `^.+$', which matches lines with at least one character besides a newline, would make each such line into a sort record. *Note Regular Expressions::, for a description of the syntax and meaning of regular expressions. The value of the KEY-REGEXP argument specifies what part of each record is to be compared against the other records. The KEY-REGEXP could match the whole record, or only a part. In the latter case, the rest of the record has no effect on the sorted order of records, but it is carried along when the record moves to its new position. The KEY-REGEXP argument can refer to the text matched by a subexpression of RECORD-REGEXP, or it can be a regular expression on its own. If KEY-REGEXP is: `\DIGIT' then the text matched by the DIGITth `$...$' parenthesis grouping in RECORD-REGEXP is used for sorting. `\&' then the whole record is used for sorting. a regular expression then the function searches for a match for the regular expression within the record. If such a match is found, it is used for sorting. If a match for KEY-REGEXP is not found within a record then that record is ignored, which means its position in the buffer is not changed. (The other records may move around it.) For example, if you plan to sort all the lines in the region by the first word on each line starting with the letter `f', you should set RECORD-REGEXP to `^.*$' and set KEY-REGEXP to `\<f\w*\>'. The resulting expression looks like this: (sort-regexp-fields nil "^.*$" "\\<f\\w*\\>" (region-beginning) (region-end)) If you call `sort-regexp-fields' interactively, you are prompted for RECORD-REGEXP and KEY-REGEXP in the minibuffer. -- Command: sort-subr REVERSE NEXTRECFUN ENDRECFUN &optional STARTKEYFUN ENDKEYFUN This command is the general text sorting routine that divides a buffer into records and sorts them. The functions `sort-lines', `sort-paragraphs', `sort-pages', `sort-fields', `sort-regexp-fields' and `sort-numeric-fields' all use `sort-subr'. To understand how `sort-subr' works, consider the whole accessible portion of the buffer as being divided into disjoint pieces called "sort records". A portion of each sort record (perhaps all of it) is designated as the sort key. The records are rearranged in the buffer in order by their sort keys. The records may or may not be contiguous. Usually, the records are rearranged in order of ascending sort key. If the first argument to the `sort-subr' function, REVERSE, is non-`nil', the sort records are rearranged in order of descending sort key. The next four arguments to `sort-subr' are functions that are called to move point across a sort record. They are called many times from within `sort-subr'. 1. NEXTRECFUN is called with point at the end of a record. This function moves point to the start of the next record. The first record is assumed to start at the position of point when `sort-subr' is called. (Therefore, you should usually move point to the beginning of the buffer before calling `sort-subr'.) 2. ENDRECFUN is called with point within a record. It moves point to the end of the record. 3. STARTKEYFUN is called to move point from the start of a record to the start of the sort key. This argument is optional. If supplied, the function should either return a non-`nil' value to be used as the sort key, or return `nil' to indicate that the sort key is in the buffer starting at point. In the latter case, and ENDKEYFUN will be called to find the end of the sort key. 4. ENDKEYFUN is called to move point from the start of the sort key to the end of the sort key. This argument is optional. If STARTKEYFUN returns `nil' and this argument is omitted (or `nil'), then the sort key extends to the end of the record. There is no need for ENDKEYFUN if STARTKEYFUN returns a non-`nil' value. As an example of `sort-subr', here is the complete function definition for `sort-lines': (defun sort-lines (reverse beg end) "Sort lines in region alphabetically; arg means reverse order. Called from a program, there are three arguments: REVERSE (non-nil means reverse order), and BEG and END (the region to sort)." (interactive "P\nr") (save-restriction (narrow-to-region beg end) (goto-char (point-min)) (sort-subr reverse 'forward-line 'end-of-line))) Here `forward-line' moves point to the start of the next record, and `end-of-line' moves point to the end of record. We do not pass the arguments STARTKEYFUN and ENDKEYFUN, because the entire record is used as the sort key. The `sort-paragraphs' function is very much the same, except that its `sort-subr' call looks like this: (sort-subr reverse (function (lambda () (skip-chars-forward "\n \t\f"))) 'forward-paragraph))) -- Command: sort-lines REVERSE START END This command sorts lines in the region between START and END alphabetically. If REVERSE is non-`nil', the sort is in reverse order. -- Command: sort-paragraphs REVERSE START END This command sorts paragraphs in the region between START and END alphabetically. If REVERSE is non-`nil', the sort is in reverse order. -- Command: sort-pages REVERSE START END This command sorts pages in the region between START and END alphabetically. If REVERSE is non-`nil', the sort is in reverse order. -- Command: sort-fields FIELD START END This command sorts lines in the region between START and END, comparing them alphabetically by the FIELDth field of each line. Fields are separated by whitespace and numbered starting from 1. If FIELD is negative, sorting is by the -FIELDth field from the end of the line. This command is useful for sorting tables. -- Command: sort-numeric-fields FIELD START END This command sorts lines in the region between START and END, comparing them numerically by the FIELDth field of each line. Fields are separated by whitespace and numbered starting from 1. The specified field must contain a number in each line of the region. If FIELD is negative, sorting is by the -FIELDth field from the end of the line. This command is useful for sorting tables. -- Command: sort-columns REVERSE &optional BEG END This command sorts the lines in the region between BEG and END, comparing them alphabetically by a certain range of columns. For the purpose of this command, the region includes the entire line that point is in and the entire line containing END. The column positions of BEG and END bound the range of columns to sort on. If REVERSE is non-`nil', the sort is in reverse order. One unusual thing about this command is that the entire line containing point, and the entire line containing the mark, are included in the region sorted. Note that `sort-columns' uses the `sort' utility program, and so cannot work properly on text containing tab characters. Use `M-x `untabify'' to convert tabs to spaces before sorting. The `sort-columns' function doesn't work in VMS, because the subprocess facilities are lacking. File: elisp, Node: Indentation, Next: Columns, Prev: Sorting, Up: Text Indentation =========== The indentation functions are used to examine, move to, and change whitespace that is at the beginning of a line. Some of the functions can also change whitespace elsewhere on a line. Indentation always counts from zero at the left margin. * Menu: * Primitive Indent:: Functions used to count and insert indentation. * Mode-Specific Indent:: Customize indentation for different modes. * Region Indent:: Indent all the lines in a region. * Relative Indent:: Indent the current line based on previous lines. * Indent Tabs:: Adjustable, typewriter-like tab stops. * Motion by Indent:: Move to first non-blank character. File: elisp, Node: Primitive Indent, Next: Mode-Specific Indent, Prev: Indentation, Up: Indentation Indentation Primitives ---------------------- This section describes the primitive functions used to count and insert indentation. The functions in the following sections use these primitives. -- Function: current-indentation This function returns the indentation of the current line, which is the horizontal position of the first nonblank character. If the contents are entirely blank, then this is the horizontal position of the end of the line. -- Command: indent-to COLUMN &optional MINIMUM This function indents from point with tabs and spaces until COLUMN is reached. If MINIMUM is specified and non-`nil', then at least that many spaces are inserted even if this requires going beyond COLUMN. The value is the column at which the inserted indentation ends. -- User Option: indent-tabs-mode If this variable is non-`nil', indentation functions can insert tabs as well as spaces. Otherwise, they insert only spaces. Setting this variable automatically makes it local to the current buffer. File: elisp, Node: Mode-Specific Indent, Next: Region Indent, Prev: Primitive Indent, Up: Indentation Indentation Controlled by Major Mode ------------------------------------ An important function of each major mode is to customize the TAB key to indent properly for the language being edited. This section describes the mechanism of the TAB key and how to control it. The functions in this section return unpredictable values. -- Variable: indent-line-function This variable's value is the function to be used by TAB (and various commands) to indent the current line. The command `indent-according-to-mode' does no more than call this function. In Lisp mode, the value is the symbol `lisp-indent-line'; in C mode, `c-indent-line'; in Fortran mode, `fortran-indent-line'. In Fundamental mode, Text mode, and many other modes with no standard for indentation, the value is `indent-to-left-margin' (which is the default value). -- Command: indent-according-to-mode This command calls the function in `indent-line-function' to indent the current line in a way appropriate for the current major mode. -- Command: indent-for-tab-command This command calls the function in `indent-line-function' to indent the current line, except that if that function is `indent-to-left-margin', `insert-tab' is called instead. -- Variable: left-margin This variable is the column to which the default `indent-line-function' will indent. (That function is `indent-to-left-margin'.) In Fundamental mode, LFD indents to this column. This variable automatically becomes buffer-local when set in any fashion. -- Function: indent-to-left-margin This is the default `indent-line-function', used in Fundamental mode, Text mode, etc. Its effect is to adjust the indentation at the beginning of the current line to the value specified by the variable `left-margin'. This may involve either inserting or deleting whitespace. -- Command: newline-and-indent This function inserts a newline, then indents the new line (the one following the newline just inserted) according to the major mode. Indentation is done using the current `indent-line-function'. In programming language modes, this is the same thing TAB does, but in some text modes, where TAB inserts a tab, `newline-and-indent' indents to the column specified by `left-margin'. -- Command: reindent-then-newline-and-indent This command reindents the current line, inserts a newline at point, and then reindents the new line (the one following the newline just inserted). Indentation of both lines is done according to the current major mode; this means that the current value of `indent-line-function' is called. In programming language modes, this is the same thing TAB does, but in some text modes, where TAB inserts a tab, `reindent-then-newline-and-indent' indents to the column specified by `left-margin'. File: elisp, Node: Region Indent, Next: Relative Indent, Prev: Mode-Specific Indent, Up: Indentation Indenting an Entire Region -------------------------- This section describes commands which indent all the lines in the region. They return unpredictable values. -- Command: indent-region START END TO-COLUMN This command indents each nonblank line starting between START (inclusive) and END (exclusive). If TO-COLUMN is `nil', `indent-region' indents each nonblank line by calling the current mode's indentation function, the value of `indent-line-function'. If TO-COLUMN is non-`nil', it should be an integer specifying the number of columns of indentation; then this function gives each line exactly that much indentation, by either adding or deleting whitespace. -- Variable: indent-region-function The value of this variable is a function that can be used by `indent-region' as a short cut. You should design the function so that it will produce the same results as indenting the lines of the region one by one (but presumably faster). If the value is `nil', there is no short cut, and `indent-region' actually works line by line. A short cut function is useful in modes such as C mode and Lisp mode, where the `indent-line-function' must scan from the beginning of the function: applying it to each line would be quadratic in time. The short cut can update the scan information as it moves through the lines indenting them; this takes linear time. If indenting a line individually is fast, there is no need for a short cut. `indent-region' with a non-`nil' argument has a different definition and does not use this variable. -- Command: indent-rigidly START END COUNT This command indents all lines starting between START (inclusive) and END (exclusive) sideways by `count' columns. This "preserves the shape" of the affected region, moving it as a rigid unit. Consequently, this command is useful not only for indenting regions of unindented text, but also for indenting regions of formatted code. For example, if COUNT is 3, this command adds 3 columns of indentation to each of the lines beginning in the region specified. In Mail mode, `C-c C-y' (`mail-yank-original') uses `indent-rigidly' to indent the text copied from the message being replied to. File: elisp, Node: Relative Indent, Next: Indent Tabs, Prev: Region Indent, Up: Indentation Indentation Relative to Previous Lines -------------------------------------- This section describes two commands which indent the current line based on the contents of previous lines. -- Command: indent-relative &optional UNINDENTED-OK This function inserts whitespace at point, extending to the same column as the next "indent point" of the previous nonblank line. An indent point is a non-whitespace character following whitespace. The next indent point is the first one at a column greater than the current column of point. For example, if point is underneath and to the left of the first non-blank character of a line of text, it moves to that column by inserting whitespace. If the previous nonblank line has no next indent point (i.e., none at a great enough column position), this function either does nothing (if UNINDENTED-OK is non-`nil') or calls `tab-to-tab-stop'. Thus, if point is underneath and to the right of the last column of a short line of text, this function moves point to the next tab stop by inserting whitespace. This command returns an unpredictable value. In the following example, point is at the beginning of the second line: This line is indented twelve spaces. -!-The quick brown fox jumped over the lazy dog. Evaluation of the expression `(indent-relative nil)' produces the following: This line is indented twelve spaces. -!-The quick brown fox jumped over the lazy dog. In this example, point is between the `m' and `p' of `jumped': This line is indented twelve spaces. The quick brown fox jum-!-ped over the lazy dog. Evaluation of the expression `(indent-relative nil)' produces the following: This line is indented twelve spaces. The quick brown fox jum -!-ped over the lazy dog. -- Command: indent-relative-maybe This command indents the current line like the previous nonblank line. The function consists of a call to `indent-relative' with a non-`nil' value passed to the UNINDENTED-OK optional argument. The value is unpredictable. If the previous line has no indentation, the current line is given no indentation (any existing indentation is deleted); if the previous nonblank line has no indent points beyond the column at which point starts, nothing is changed. File: elisp, Node: Indent Tabs, Next: Motion by Indent, Prev: Relative Indent, Up: Indentation Adjustable "Tab Stops" ---------------------- This section explains the mechanism for user-specified "tab stops" and the mechanisms which use and set them. The name "tab stops" is used because the feature is similar to that of the tab stops on a typewriter. The feature works by inserting an appropriate number of spaces and tab characters to reach the designated position, like the other indentation functions; it does not affect the display of tab characters in the buffer (*note Control Char Display::.). Note that the TAB character as input uses this tab stop feature only in a few major modes, such as Text mode. -- Function: tab-to-tab-stop This function inserts spaces or tabs up to the next tab stop column defined by `tab-stop-list'. It searches the list for an element greater than the current column number, and uses that element as the column to indent to. If no such element is found, then nothing is done. -- User Option: tab-stop-list This variable is the list of tab stop columns used by `tab-to-tab-stops'. The elements should be integers in increasing order. The tab stop columns need not be evenly spaced. Use `M-x edit-tab-stops' to edit the location of tab stops interactively. File: elisp, Node: Motion by Indent, Prev: Indent Tabs, Up: Indentation Indentation-Based Motion Commands --------------------------------- These commands, primarily for interactive use, act based on the indentation in the text. -- Command: back-to-indentation This command moves point to the first non-whitespace character in the current line (which is the line in which point is located). It returns `nil'. -- Command: backward-to-indentation ARG This command moves point backward ARG lines and then to the first nonblank character on that line. It returns `nil'. -- Command: forward-to-indentation ARG This command moves point forward ARG lines and then to the first nonblank character on that line. It returns `nil'. File: elisp, Node: Columns, Next: Case Changes, Prev: Indentation, Up: Text Counting Columns ================ The column functions convert between a character position (counting characters from the beginning of the buffer) and a column position (counting screen characters from the beginning of a line). Column number computations ignore the width of the window and the amount of horizontal scrolling. Consequently, a column value can be arbitrarily high. The first (or leftmost) column is numbered 0. A character counts according to the number of columns it occupies on the screen. This means control characters count as occupying 2 or 4 columns, depending upon the value of `ctl-arrow', and tabs count as occupying a number of columns that depends on the value of `tab-width' and on the column where the tab begins. *Note Control Char Display::. -- Function: current-column This function returns the horizontal position of point, measured in columns, counting from 0 at the left margin. The column count is calculated by adding together the widths of all the displayed representations of the characters between the start of the current line and point. For a more complicated example of the use of `current-column', see the description of `count-lines' in *Note Text Lines::. -- Function: move-to-column COLUMN This function moves point to COLUMN in the current line. The calculation of COLUMN takes into account the widths of all the displayed representations of the characters between the start of the line and point. If the argument COLUMN is greater than the column position of the end of the line, point moves to the end of the line. If COLUMN is negative, point moves to the beginning of the line. An error is signaled if COLUMN is not an integer. The return value is the column number actually moved to.