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GNU Info File | 1995-09-01 | 49.8 KB | 1,179 lines

This is Info file ../../info/xemacs.info, produced by Makeinfo-1.63 from the input file xemacs.texi. This file documents the XEmacs editor. Copyright (C) 1985, 1986, 1988 Richard M. Stallman. Copyright (C) 1991, 1992, 1993, 1994 Lucid, Inc. Copyright (C) 1993, 1994 Sun Microsystems, Inc. Copyright (C) 1995 Amdahl Corporation. 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 also that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" are included exactly as in the original, and 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 the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" may be included in a translation approved by the author instead of in the original English. File: xemacs.info, Node: Active Regions, Prev: X Cut Buffers, Up: Using X Selections Active Regions -------------- By default, both the text you select in an Emacs buffer using the click-and-drag mechanism and text you select by setting point and the mark is highlighted. You can use Emacs region commands as well as the Cut and Copy commands on the highlighted region you selected with the mouse. If you prefer, you can make a distinction between text selected with the mouse and text selected with point and the mark by setting the variable `zmacs-regions' to `nil'. In that case: * The text selected with the mouse becomes both the X selection and the Emacs selected region. You can use menu-bar commands as well as Emacs region commands on it. * The text selected with point and the mark is not highlighted. You can only use Emacs region commands on it, not the menu-bar items. Active regions originally come from Zmacs, the Lisp Machine editor. The idea behind them is that commands can only operate on a region when the region is in an "active" state. Put simply, you can only operate on a region that is highlighted. The variable `zmacs-regions' checks whether LISPM-style active regions should be used. This means that commands that operate on the region (the area between point and the mark) only work while the region is in the active state, which is indicated by highlighting. Most commands causes the region to not be in the active state; for example, `C-w' only works immediately after activating the region. More specifically: * Commands that operate on the region only work if the region is active. * Only a very small set of commands causes the region to become active-- those commands whose semantics are to mark an area, such as `mark-defun'. * The region is deactivated after each command that is executed, except that motion commands do not change whether the region is active or not. `set-mark-command' (`C-SPC') pushes a mark and activates the region. Moving the cursor with normal motion commands (`C-n', `C-p', etc.) will cause the region between point and the recently-pushed mark to be highlighted. It will remain highlighted until some non-motion comand is executed. `exchange-point-and-mark' (`C-x C-x') activates the region. So if you mark a region and execute a command that operates on it, you can reactivate the same region with `C-x C-x' (or perhaps `C-x C-x C-x C-x') to operate on it again. Generally, commands that push marks as a means of navigation, such as `beginning-of-buffer' (`M-<') and `end-of-buffer' (`M->'), do not activate the region. However, commands that push marks as a means of marking an area of text, such as `mark-defun' (`M-C-h'), `mark-word' (`M-@'), and `mark-whole-buffer' (`C-x h'), do activate the region. When `zmacs-regions' is `t', there is no distinction between the primary X selection and the active region selected by point and the mark. To see this, set the mark (C-SPC) and move the cursor with any cursor-motion command: the region between point and mark is highlighted, and you can watch it grow and shrink as you move the cursor. Any other commands besides cursor-motion commands (such as inserting or deleting text) will cause the region to no longer be active; it will no longer be highlighted, and will no longer be the primary selection. Errors also remove highlighting from a region. Commands that require a region (such as `C-w') signal an error if the region is not active. Certain commands cause the region to be in its active state. The most common ones are `push-mark' (C-SPC) and `exchange-point-and-mark' (`C-x C-x'). When `zmacs-regions' is `t', programs can be non-intrusive on the state of the region by setting the variable `zmacs-region-stays' to a non-`nil' value. If you are writing a new Emacs command that is conceptually a "motion" command and should not interfere with the current highlightedness of the region, then you may set this variable. It is reset to `nil' after each user command is executed. When `zmacs-regions' is `t', programs can make the region between point and mark go into the active (highlighted) state by using the function `zmacs-activate-region'. Only a small number of commands should ever do this. When `zmacs-regions' is `t', programs can deactivate the region between point and the mark by using `zmacs-deactivate-region'. Note: you should not have to call this function; the command loop calls it when appropriate. File: xemacs.info, Node: Accumulating Text, Next: Rectangles, Prev: Using X Selections, Up: Top Accumulating Text ================= Usually you copy or move text by killing it and yanking it, but there are other ways that are useful for copying one block of text in many places, or for copying many scattered blocks of text into one place. If you like, you can accumulate blocks of text from scattered locations either into a buffer or into a file. The relevant commands are described here. You can also use Emacs registers for storing and accumulating text. *Note Registers::. `M-x append-to-buffer' Append region to contents of specified buffer (`append-to-buffer'). `M-x prepend-to-buffer' Prepend region to contents of specified buffer. `M-x copy-to-buffer' Copy region into specified buffer, deleting that buffer's old contents. `M-x insert-buffer' Insert contents of specified buffer into current buffer at point. `M-x append-to-file' Append region to the end of the contents of specified file. To accumulate text into a buffer, use the command `M-x append-to-buffer', which inserts a copy of the region into the buffer BUFFERNAME, at the location of point in that buffer. If there is no buffer with the given name, one is created. If you append text to a buffer that has been used for editing, the copied text goes to the place where point is. Point in that buffer is left at the end of the copied text, so successive uses of `append-to-buffer' accumulate the text in the specified buffer in the same order as they were copied. Strictly speaking, this command does not always append to the text already in the buffer; but if this command is the only command used to alter a buffer, it does always append to the existing text because point is always at the end. `M-x prepend-to-buffer' is similar to `append-to-buffer', but point in the other buffer is left before the copied text, so successive prependings add text in reverse order. `M-x copy-to-buffer' is similar, except that any existing text in the other buffer is deleted, so the buffer is left containing just the text newly copied into it. You can retrieve the accumulated text from that buffer with `M-x insert-buffer', which takes BUFFERNAME as an argument. It inserts a copy of the text in buffer BUFFERNAME into the selected buffer. You could alternatively select the other buffer for editing, perhaps moving text from it by killing or with `append-to-buffer'. *Note Buffers::, for background information on buffers. Instead of accumulating text within Emacs in a buffer, you can append text directly into a file with `M-x append-to-file', which takes FILE-NAME as an argument. It adds the text of the region to the end of the specified file. The file is changed immediately on disk. This command is normally used with files that are not being visited in Emacs. Using it on a file that Emacs is visiting can produce confusing results, because the file's text inside Emacs does not change while the file itself changes. File: xemacs.info, Node: Rectangles, Next: Registers, Prev: Accumulating Text, Up: Top Rectangles ========== The rectangle commands affect rectangular areas of text: all characters between a certain pair of columns, in a certain range of lines. Commands are provided to kill rectangles, yank killed rectangles, clear them out, or delete them. Rectangle commands are useful with text in multicolumnar formats, like code with comments at the right, or for changing text into or out of such formats. To specify the rectangle a command should work on, put the mark at one corner and point at the opposite corner. The specified rectangle is called the "region-rectangle" because it is controlled about the same way the region is controlled. Remember that a given combination of point and mark values can be interpreted either as specifying a region or as specifying a rectangle; it is up to the command that uses them to choose the interpretation. `M-x delete-rectangle' Delete the text of the region-rectangle, moving any following text on each line leftward to the left edge of the region-rectangle. `M-x kill-rectangle' Similar, but also save the contents of the region-rectangle as the "last killed rectangle". `M-x yank-rectangle' Yank the last killed rectangle with its upper left corner at point. `M-x open-rectangle' Insert blank space to fill the space of the region-rectangle. The previous contents of the region-rectangle are pushed rightward. `M-x clear-rectangle' Clear the region-rectangle by replacing its contents with spaces. The rectangle operations fall into two classes: commands deleting and moving rectangles, and commands for blank rectangles. There are two ways to get rid of the text in a rectangle: you can discard the text (delete it) or save it as the "last killed" rectangle. The commands for these two ways are `M-x delete-rectangle' and `M-x kill-rectangle'. In either case, the portion of each line that falls inside the rectangle's boundaries is deleted, causing following text (if any) on the line to move left. Note that "killing" a rectangle is not killing in the usual sense; the rectangle is not stored in the kill ring, but in a special place that only records the most recently killed rectangle (that is, does not append to a killed rectangle). Different yank commands have to be used and only one rectangle is stored, because yanking a rectangle is quite different from yanking linear text and yank-popping commands are difficult to make sense of. Inserting a rectangle is the opposite of deleting one. You specify where to put the upper left corner by putting point there. The rectangle's first line is inserted at point, the rectangle's second line is inserted at a point one line vertically down, and so on. The number of lines affected is determined by the height of the saved rectangle. To insert the last killed rectangle, type `M-x yank-rectangle'. This can be used to convert single-column lists into double-column lists; kill the second half of the list as a rectangle and then yank it beside the first line of the list. There are two commands for working with blank rectangles: `M-x clear-rectangle' erases existing text, and `M-x open-rectangle' inserts a blank rectangle. Clearing a rectangle is equivalent to deleting it and then inserting a blank rectangle of the same size. Rectangles can also be copied into and out of registers. *Note Rectangle Registers: RegRect. File: xemacs.info, Node: Registers, Next: Display, Prev: Rectangles, Up: Top Registers ********* Emacs "registers" are places in which you can save text or positions for later use. Text saved in a register can be copied into the buffer once or many times; a position saved in a register is used by moving point to that position. Rectangles can also be copied into and out of registers (*note Rectangles::.). Each register has a name, which is a single character. A register can store either a piece of text, a position, or a rectangle, but only one thing at any given time. Whatever you store in a register remains there until you store something else in that register. * Menu: * RegPos:: Saving positions in registers. * RegText:: Saving text in registers. * RegRect:: Saving rectangles in registers. `M-x view-register RET R' Display a description of what register R contains. `M-x view-register' reads a register name as an argument and then displays the contents of the specified register. File: xemacs.info, Node: RegPos, Next: RegText, Prev: Registers, Up: Registers Saving Positions in Registers ============================= Saving a position records a spot in a buffer so you can move back there later. Moving to a saved position re-selects the buffer and moves point to the spot. `C-x r SPC R' Save the location of point in register R (`point-to-register'). `C-x r j R' Jump to the location saved in register R (`register-to-point'). To save the current location of point in a register, choose a name R and type `C-x r SPC R'. The register R retains the location thus saved until you store something else in that register. The command `C-x r j R' moves point to the location recorded in register R. The register is not affected; it continues to record the same location. You can jump to the same position using the same register as often as you want. File: xemacs.info, Node: RegText, Next: RegRect, Prev: RegPos, Up: Registers Saving Text in Registers ======================== When you want to insert a copy of the same piece of text many times, it can be impractical to use the kill ring, since each subsequent kill moves the piece of text further down on the ring. It becomes hard to keep track of the argument needed to retrieve the same text with `C-y'. An alternative is to store the text in a register with `C-x r s' (`copy-to-register') and then retrieve it with `C-x r g' (`insert-register'). `C-x r s R' Copy region into register R (`copy-to-register'). `C-x r g R' Insert text contents of register R (`insert-register'). `C-x r s R' stores a copy of the text of the region into the register named R. Given a numeric argument, `C-x r s' deletes the text from the buffer as well. `C-x r g R' inserts the text from register R in the buffer. By default it leaves point before the text and places the mark after it. With a numeric argument, it puts point after the text and the mark before it. File: xemacs.info, Node: RegRect, Prev: RegText, Up: Registers Saving Rectangles in Registers ============================== A register can contain a rectangle instead of lines of text. The rectangle is represented as a list of strings. *Note Rectangles::, for basic information on rectangles and how to specify rectangles in a buffer. `C-x r r R' Copy the region-rectangle into register R(`copy-rectangle-to-register'). With a numeric argument, delete it as well. `C-x r g R' Insert the rectangle stored in register R (if it contains a rectangle) (`insert-register'). The `C-x r g' command inserts linear text if the register contains that, or inserts a rectangle if the register contains one. File: xemacs.info, Node: Display, Next: Search, Prev: Registers, Up: Top Controlling the Display *********************** Since only part of a large buffer fits in the window, Emacs tries to show the part that is likely to be interesting. The display control commands allow you to specify which part of the text you want to see. `C-l' Clear frame and redisplay, scrolling the selected window to center point vertically within it (`recenter'). `C-v' Scroll forward (a windowful or a specified number of lines) (`scroll-up'). `M-v' Scroll backward (`scroll-down'). `ARG C-l' Scroll so point is on line ARG (`recenter'). `C-x <' Scroll text in current window to the left (`scroll-left'). `C-x >' Scroll to the right (`scroll-right'). `C-x $' Make deeply indented lines invisible (`set-selective-display'). * Menu: * Scrolling:: Moving text up and down in a window. * Horizontal Scrolling:: Moving text left and right in a window. * Selective Display:: Hiding lines with lots of indentation. * Display Vars:: Information on variables for customizing display. File: xemacs.info, Node: Scrolling, Next: Horizontal Scrolling, Prev: Display, Up: Display Scrolling ========= If a buffer contains text that is too large to fit entirely within the window that is displaying the buffer, Emacs shows a contiguous section of the text. The section shown always contains point. "Scrolling" means moving text up or down in the window so that different parts of the text are visible. Scrolling forward means that text moves up, and new text appears at the bottom. Scrolling backward moves text down and new text appears at the top. Scrolling happens automatically if you move point past the bottom or top of the window. You can also explicitly request scrolling with the commands in this section. `C-l' Clear frame and redisplay, scrolling the selected window to center point vertically within it (`recenter'). `C-v' Scroll forward (a windowful or a specified number of lines) (`scroll-up'). `M-v' Scroll backward (`scroll-down'). `ARG C-l' Scroll so point is on line ARG (`recenter'). The most basic scrolling command is `C-l' (`recenter') with no argument. It clears the entire frame and redisplays all windows. In addition, it scrolls the selected window so that point is halfway down from the top of the window. The scrolling commands `C-v' and `M-v' let you move all the text in the window up or down a few lines. `C-v' (`scroll-up') with an argument shows you that many more lines at the bottom of the window, moving the text and point up together as `C-l' might. `C-v' with a negative argument shows you more lines at the top of the window. `Meta-v' (`scroll-down') is like `C-v', but moves in the opposite direction. To read the buffer a windowful at a time, use `C-v' with no argument. `C-v' takes the last two lines at the bottom of the window and puts them at the top, followed by nearly a whole windowful of lines not previously visible. Point moves to the new top of the window if it was in the text scrolled off the top. `M-v' with no argument moves backward with similar overlap. The number of lines of overlap across a `C-v' or `M-v' is controlled by the variable `next-screen-context-lines'; by default, it is two. Another way to scroll is using `C-l' with a numeric argument. `C-l' does not clear the frame when given an argument; it only scrolls the selected window. With a positive argument N, `C-l' repositions text to put point N lines down from the top. An argument of zero puts point on the very top line. Point does not move with respect to the text; rather, the text and point move rigidly on the frame. `C-l' with a negative argument puts point that many lines from the bottom of the window. For example, `C-u - 1 C-l' puts point on the bottom line, and `C-u - 5 C-l' puts it five lines from the bottom. Just `C-u' as argument, as in `C-u C-l', scrolls point to the center of the frame. Scrolling happens automatically if point has moved out of the visible portion of the text when it is time to display. Usually scrolling is done to put point vertically centered within the window. However, if the variable `scroll-step' has a non-zero value, an attempt is made to scroll the buffer by that many lines; if that is enough to bring point back into visibility, that is what happens. File: xemacs.info, Node: Horizontal Scrolling, Prev: Scrolling, Up: Display Horizontal Scrolling ==================== `C-x <' Scroll text in current window to the left (`scroll-left'). `C-x >' Scroll to the right (`scroll-right'). The text in a window can also be scrolled horizontally. This means that each line of text is shifted sideways in the window, and one or more characters at the beginning of each line are not displayed at all. When a window has been scrolled horizontally in this way, text lines are truncated rather than continued (*note Continuation Lines::.), with a `$' appearing in the first column when there is text truncated to the left, and in the last column when there is text truncated to the right. The command `C-x <' (`scroll-left') scrolls the selected window to the left by N columns with argument N. With no argument, it scrolls by almost the full width of the window (two columns less, to be precise). `C-x >' (`scroll-right') scrolls similarly to the right. The window cannot be scrolled any farther to the right once it is displaying normally (with each line starting at the window's left margin); attempting to do so has no effect. File: xemacs.info, Node: Selective Display, Next: Display Vars, Prev: Display, Up: Display Selective Display ================= Emacs can hide lines indented more than a certain number of columns (you specify how many columns). This allows you to get an overview of a part of a program. To hide lines, type `C-x $' (`set-selective-display') with a numeric argument N. (*Note Arguments::, for information on giving the argument.) Lines with at least N columns of indentation disappear from the screen. The only indication of their presence are three dots (`...'), which appear at the end of each visible line that is followed by one or more invisible ones. The invisible lines are still present in the buffer, and most editing commands see them as usual, so it is very easy to put point in the middle of invisible text. When this happens, the cursor appears at the end of the previous line, after the three dots. If point is at the end of the visible line, before the newline that ends it, the cursor appears before the three dots. The commands `C-n' and `C-p' move across the invisible lines as if they were not there. To make everything visible again, type `C-x $' with no argument. File: xemacs.info, Node: Display Vars, Prev: Selective Display, Up: Display Variables Controlling Display ============================= This section contains information for customization only. Beginning users should skip it. The variable `mode-line-inverse-video' controls whether the mode line is displayed in inverse video (assuming the terminal supports it); `nil' means don't do so. *Note Mode Line::. If the variable `inverse-video' is non-`nil', Emacs attempts to invert all the lines of the display from what they normally are. When you reenter Emacs after suspending, Emacs normally clears the screen and redraws the entire display. On some terminals with more than one page of memory, it is possible to arrange the termcap entry so that the `ti' and `te' strings (output to the terminal when Emacs is entered and exited, respectively) switch between pages of memory so as to use one page for Emacs and another page for other output. In that case, you might want to set the variable `no-redraw-on-reenter' to non-`nil' so that Emacs will assume, when resumed, that the screen page it is using still contains what Emacs last wrote there. The variable `echo-keystrokes' controls the echoing of multi-character keys; its value is the number of seconds of pause required to cause echoing to start, or zero, meaning don't echo at all. *Note Echo Area::. If the variable `ctl-arrow' is `nil', control characters in the buffer are displayed with octal escape sequences, all except newline and tab. If its value is `t', then control characters will be printed with an up-arrow, for example `^A'. If its value is not `t' and not `nil', then characters whose code is greater than 160 (that is, the space character (32) with its high bit set) will be assumed to be printable, and will be displayed without alteration. This is the default when running under X Windows, since XEmacs assumes an ISO/8859-1 character set (also known as "Latin1"). The `ctl-arrow' variable may also be set to an integer, in which case all characters whose codes are greater than or equal to that value will be assumed to be printable. Altering the value of `ctl-arrow' makes it local to the current buffer; until that time, the default value is in effect. *Note Locals::. Normally, a tab character in the buffer is displayed as whitespace which extends to the next display tab stop position, and display tab stops come at intervals equal to eight spaces. The number of spaces per tab is controlled by the variable `tab-width', which is made local by changing it, just like `ctl-arrow'. Note that how the tab character in the buffer is displayed has nothing to do with the definition of TAB as a command. If you set the variable `selective-display-ellipses' to `nil', the three dots at the end of a line that precedes invisible lines do not appear. There is no visible indication of the invisible lines. This variable becomes local automatically when set. File: xemacs.info, Node: Search, Next: Fixit, Prev: Display, Up: Top Searching and Replacement ************************* Like other editors, Emacs has commands for searching for occurrences of a string. The principal search command is unusual in that it is "incremental": it begins to search before you have finished typing the search string. There are also non-incremental search commands more like those of other editors. Besides the usual `replace-string' command that finds all occurrences of one string and replaces them with another, Emacs has a fancy replacement command called `query-replace' which asks interactively which occurrences to replace. * Menu: * Incremental Search:: Search happens as you type the string. * Non-Incremental Search:: Specify entire string and then search. * Word Search:: Search for sequence of words. * Regexp Search:: Search for match for a regexp. * Regexps:: Syntax of regular expressions. * Search Case:: To ignore case while searching, or not. * Replace:: Search, and replace some or all matches. * Other Repeating Search:: Operating on all matches for some regexp. File: xemacs.info, Node: Incremental Search, Next: Non-Incremental Search, Prev: Search, Up: Search Incremental Search ================== An incremental search begins searching as soon as you type the first character of the search string. As you type in the search string, Emacs shows you where the string (as you have typed it so far) is found. When you have typed enough characters to identify the place you want, you can stop. Depending on what you do next, you may or may not need to terminate the search explicitly with a RET. `C-s' Incremental search forward (`isearch-forward'). `C-r' Incremental search backward (`isearch-backward'). `C-s' starts an incremental search. `C-s' reads characters from the keyboard and positions the cursor at the first occurrence of the characters that you have typed. If you type `C-s' and then `F', the cursor moves right after the first `F'. Type an `O', and see the cursor move to after the first `FO'. After another `O', the cursor is after the first `FOO' after the place where you started the search. Meanwhile, the search string `FOO' has been echoed in the echo area. The echo area display ends with three dots when actual searching is going on. When search is waiting for more input, the three dots are removed. (On slow terminals, the three dots are not displayed.) If you make a mistake in typing the search string, you can erase characters with DEL. Each DEL cancels the last character of the search string. This does not happen until Emacs is ready to read another input character; first it must either find, or fail to find, the character you want to erase. If you do not want to wait for this to happen, use `C-g' as described below. When you are satisfied with the place you have reached, you can type RET (or C-m), which stops searching, leaving the cursor where the search brought it. Any command not specially meaningful in searches also stops the search and is then executed. Thus, typing `C-a' exits the search and then moves to the beginning of the line. RET is necessary only if the next command you want to type is a printing character, DEL, ESC, or another control character that is special within searches (`C-q', `C-w', `C-r', `C-s', or `C-y'). Sometimes you search for `FOO' and find it, but were actually looking for a different occurance of it. To move to the next occurrence of the search string, type another `C-s'. Do this as often as necessary. If you overshoot, you can cancel some `C-s' characters with DEL. After you exit a search, you can search for the same string again by typing just `C-s C-s': the first `C-s' is the key that invokes incremental search, and the second `C-s' means "search again". If the specified string is not found at all, the echo area displays the text `Failing I-Search'. The cursor is after the place where Emacs found as much of your string as it could. Thus, if you search for `FOOT', and there is no `FOOT', the cursor may be after the `FOO' in `FOOL'. At this point there are several things you can do. If you mistyped the search string, correct it. If you like the place you have found, you can type RET or some other Emacs command to "accept what the search offered". Or you can type `C-g', which removes from the search string the characters that could not be found (the `T' in `FOOT'), leaving those that were found (the `FOO' in `FOOT'). A second `C-g' at that point cancels the search entirely, returning point to where it was when the search started. If a search is failing and you ask to repeat it by typing another `C-s', it starts again from the beginning of the buffer. Repeating a failing backward search with `C-r' starts again from the end. This is called "wrapping around". `Wrapped' appears in the search prompt once this has happened. The `C-g' "quit" character does special things during searches; just what it does depends on the status of the search. If the search has found what you specified and is waiting for input, `C-g' cancels the entire search. The cursor moves back to where you started the search. If `C-g' is typed when there are characters in the search string that have not been found--because Emacs is still searching for them, or because it has failed to find them--then the search string characters which have not been found are discarded from the search string. The search is now successful and waiting for more input, so a second `C-g' cancels the entire search. To search for a control character such as `C-s' or DEL or ESC, you must quote it by typing `C-q' first. This function of `C-q' is analogous to its meaning as an Emacs command: it causes the following character to be treated the way a graphic character would normally be treated in the same context. To search backwards, you can use `C-r' instead of `C-s' to start the search; `C-r' is the key that runs the command (`isearch-backward') to search backward. You can also use `C-r' to change from searching forward to searching backwards. Do this if a search fails because the place you started was too far down in the file. Repeated `C-r' keeps looking for more occurrences backwards. `C-s' starts going forward again. You can cancel `C-r' in a search with DEL. The characters `C-y' and `C-w' can be used in incremental search to grab text from the buffer into the search string. This makes it convenient to search for another occurrence of text at point. `C-w' copies the word after point as part of the search string, advancing point over that word. Another `C-s' to repeat the search will then search for a string including that word. `C-y' is similar to `C-w' but copies the rest of the current line into the search string. The characters `M-p' and `M-n' can be used in an incremental search to recall things which you have searched for in the past. A list of the last 16 things you have searched for is retained, and `M-p' and `M-n' let you cycle through that ring. The character `M-TAB' does completion on the elements in the search history ring. For example, if you know that you have recently searched for the string `POTATOE', you could type `C-s P O M-TAB'. If you had searched for other strings beginning with `PO' then you would be shown a list of them, and would need to type more to select one. You can change any of the special characters in incremental search via the normal keybinding mechanism: simply add a binding to the `isearch-mode-map'. For example, to make the character `C-b' mean "search backwards" while in isearch-mode, do this: (define-key isearch-mode-map "\C-b" 'isearch-repeat-backward) These are the default bindings of isearch-mode: `DEL' Delete a character from the incremental search string (`isearch-delete-char'). `RET' Exit incremental search (`isearch-exit'). `C-q' Quote special characters for incremental search (`isearch-quote-char'). `C-s' Repeat incremental search forward (`isearch-repeat-forward'). `C-r' Repeat incremental search backward (`isearch-repeat-backward'). `C-y' Pull rest of line from buffer into search string (`isearch-yank-line'). `C-w' Pull next word from buffer into search string (`isearch-yank-word'). `C-g' Cancels input back to what has been found successfully, or aborts the isearch (`isearch-abort'). `M-p' Recall the previous element in the isearch history ring (`isearch-ring-retreat'). `M-n' Recall the next element in the isearch history ring (`isearch-ring-advance'). `M-TAB' Do completion on the elements in the isearch history ring (`isearch-complete'). Any other character which is normally inserted into a buffer when typed is automatically added to the search string in isearch-mode. Slow Terminal Incremental Search -------------------------------- Incremental search on a slow terminal uses a modified style of display that is designed to take less time. Instead of redisplaying the buffer at each place the search gets to, it creates a new single-line window and uses that to display the line the search has found. The single-line window appears as soon as point gets outside of the text that is already on the screen. When the search is terminated, the single-line window is removed. Only at this time the window in which the search was done is redisplayed to show its new value of point. The three dots at the end of the search string, normally used to indicate that searching is going on, are not displayed in slow style display. The slow terminal style of display is used when the terminal baud rate is less than or equal to the value of the variable `search-slow-speed', initially 1200. The number of lines to use in slow terminal search display is controlled by the variable `search-slow-window-lines'. Its normal value is 1. File: xemacs.info, Node: Non-Incremental Search, Next: Word Search, Prev: Incremental Search, Up: Search Non-Incremental Search ====================== Emacs also has conventional non-incremental search commands, which require you type the entire search string before searching begins. `C-s RET STRING RET' Search for STRING. `C-r RET STRING RET' Search backward for STRING. To do a non-incremental search, first type `C-s RET' (or `C-s C-m'). This enters the minibuffer to read the search string. Terminate the string with RET to start the search. If the string is not found, the search command gets an error. By default, `C-s' invokes incremental search, but if you give it an empty argument, which would otherwise be useless, it invokes non-incremental search. Therefore, `C-s RET' invokes non-incremental search. `C-r RET' also works this way. Forward and backward non-incremental searches are implemented by the commands `search-forward' and `search-backward'. You can bind these commands to keys. The reason that incremental search is programmed to invoke them as well is that `C-s RET' is the traditional sequence of characters used in Emacs to invoke non-incremental search. Non-incremental searches performed using `C-s RET' do not call `search-forward' right away. They first check if the next character is `C-w', which requests a word search. *Note Word Search::. File: xemacs.info, Node: Word Search, Next: Regexp Search, Prev: Non-Incremental Search, Up: Search Word Search =========== Word search looks for a sequence of words without regard to how the words are separated. More precisely, you type a string of many words, using single spaces to separate them, and the string is found even if there are multiple spaces, newlines or other punctuation between the words. Word search is useful in editing documents formatted by text formatters. If you edit while looking at the printed, formatted version, you can't tell where the line breaks are in the source file. Word search, allows you to search without having to know the line breaks. `C-s RET C-w WORDS RET' Search for WORDS, ignoring differences in punctuation. `C-r RET C-w WORDS RET' Search backward for WORDS, ignoring differences in punctuation. Word search is a special case of non-incremental search. It is invoked with `C-s RET C-w' followed by the search string, which must always be terminated with another RET. Being non-incremental, this search does not start until the argument is terminated. It works by constructing a regular expression and searching for that. *Note Regexp Search::. You can do a backward word search with `C-r RET C-w'. Forward and backward word searches are implemented by the commands `word-search-forward' and `word-search-backward'. You can bind these commands to keys. The reason that incremental search is programmed to invoke them as well is that `C-s RET C-w' is the traditional Emacs sequence of keys for word search. File: xemacs.info, Node: Regexp Search, Next: Regexps, Prev: Word Search, Up: Search Regular Expression Search ========================= A "regular expression" ("regexp", for short) is a pattern that denotes a set of strings, possibly an infinite set. Searching for matches for a regexp is a powerful operation that editors on Unix systems have traditionally offered. In XEmacs, you can search for the next match for a regexp either incrementally or not. Incremental search for a regexp is done by typing `M-C-s' (`isearch-forward-regexp'). This command reads a search string incrementally just like `C-s', but it treats the search string as a regexp rather than looking for an exact match against the text in the buffer. Each time you add text to the search string, you make the regexp longer, and the new regexp is searched for. A reverse regexp search command `isearch-backward-regexp' also exists, but no key runs it. All of the control characters that do special things within an ordinary incremental search have the same functionality in incremental regexp search. Typing `C-s' or `C-r' immediately after starting a search retrieves the last incremental search regexp used: incremental regexp and non-regexp searches have independent defaults. Non-incremental search for a regexp is done by the functions `re-search-forward' and `re-search-backward'. You can invoke them with `M-x' or bind them to keys. You can also call `re-search-forward' by way of incremental regexp search with `M-C-s RET'. File: xemacs.info, Node: Regexps, Next: Search Case, Prev: Regexp Search, Up: Search Syntax of Regular Expressions ============================= Regular expressions have a syntax in which a few characters are special constructs and the rest are "ordinary". An ordinary character is a simple regular expression which matches that character and nothing else. The special characters are `$', `^', `.', `*', `+', `?', `[', `]' and `\'; no new special characters will be defined. Any other character appearing in a regular expression is ordinary, unless a `\' precedes it. For example, `f' is not a special character, so it is ordinary, and therefore `f' is a regular expression that matches the string `f' and no other string. (It does not match the string `ff'.) Likewise, `o' is a regular expression that matches only `o'. Any two regular expressions A and B can be concatenated. The result is a regular expression which matches a string if A matches some amount of the beginning of that string and B matches the rest of the string. As a simple example, you can concatenate the regular expressions `f' and `o' to get the regular expression `fo', which matches only the string `fo'. To do something nontrivial, you need to use one of the following special characters: `. (Period)' is a special character that matches any single character except a newline. Using concatenation, you can make regular expressions like `a.b', which matches any three-character string which begins with `a' and ends with `b'. `*' is not a construct by itself; it is a suffix, which means the preceding regular expression is to be repeated as many times as possible. In `fo*', the `*' applies to the `o', so `fo*' matches one `f' followed by any number of `o's. The case of zero `o's is allowed: `fo*' does match `f'. `*' always applies to the smallest possible preceding expression. Thus, `fo*' has a repeating `o', not a repeating `fo'. The matcher processes a `*' construct by immediately matching as many repetitions as it can find. Then it continues with the rest of the pattern. If that fails, backtracking occurs, discarding some of the matches of the `*'-modified construct in case that makes it possible to match the rest of the pattern. For example, matching `ca*ar' against the string `caaar', the `a*' first tries to match all three `a's; but the rest of the pattern is `ar' and there is only `r' left to match, so this try fails. The next alternative is for `a*' to match only two `a's. With this choice, the rest of the regexp matches successfully. `+' is a suffix character similar to `*' except that it requires that the preceding expression be matched at least once. For example, `ca+r' will match the strings `car' and `caaaar' but not the string `cr', whereas `ca*r' would match all three strings. `?' is a suffix character similar to `*' except that it can match the preceding expression either once or not at all. For example, `ca?r' will match `car' or `cr'; nothing else. `[ ... ]' `[' begins a "character set", which is terminated by a `]'. In the simplest case, the characters between the two form the set. Thus, `[ad]' matches either one `a' or one `d', and `[ad]*' matches any string composed of just `a's and `d's (including the empty string), from which it follows that `c[ad]*r' matches `cr', `car', `cdr', `caddaar', etc. You can include character ranges in a character set by writing two characters with a `-' between them. Thus, `[a-z]' matches any lower-case letter. Ranges may be intermixed freely with individual characters, as in `[a-z$%.]', which matches any lower- case letter or `$', `%', or period. Note that inside a character set the usual special characters are not special any more. A completely different set of special characters exists inside character sets: `]', `-', and `^'. To include a `]' in a character set, you must make it the first character. For example, `[]a]' matches `]' or `a'. To include a `-', write `---', which is a range containing only `-'. To include `^', make it other than the first character in the set. `[^ ... ]' `[^' begins a "complement character set", which matches any character except the ones specified. Thus, `[^a-z0-9A-Z]' matches all characters except letters and digits. `^' is not special in a character set unless it is the first character. The character following the `^' is treated as if it were first (`-' and `]' are not special there). Note that a complement character set can match a newline, unless newline is mentioned as one of the characters not to match. `^' is a special character that matches the empty string, but only if at the beginning of a line in the text being matched. Otherwise, it fails to match anything. Thus, `^foo' matches a `foo' that occurs at the beginning of a line. `$' is similar to `^' but matches only at the end of a line. Thus, `xx*$' matches a string of one `x' or more at the end of a line. `\' does two things: it quotes the special characters (including `\'), and it introduces additional special constructs. Because `\' quotes special characters, `\$' is a regular expression that matches only `$', and `\[' is a regular expression that matches only `[', and so on. Note: for historical compatibility, special characters are treated as ordinary ones if they are in contexts where their special meanings make no sense. For example, `*foo' treats `*' as ordinary since there is no preceding expression on which the `*' can act. It is poor practice to depend on this behavior; better to quote the special character anyway, regardless of where is appears. Usually, `\' followed by any character matches only that character. However, there are several exceptions: characters which, when preceded by `\', are special constructs. Such characters are always ordinary when encountered on their own. Here is a table of `\' constructs. `\|' specifies an alternative. Two regular expressions A and B with `\|' in between form an expression that matches anything A or B matches. Thus, `foo\|bar' matches either `foo' or `bar' but no other string. `\|' applies to the largest possible surrounding expressions. Only a surrounding `$ ... $' grouping can limit the grouping power of `\|'. Full backtracking capability exists to handle multiple uses of `\|'. `$ ... $' is a grouping construct that serves three purposes: 1. To enclose a set of `\|' alternatives for other operations. Thus, `$foo\|bar$x' matches either `foox' or `barx'. 2. To enclose a complicated expression for the postfix `*' to operate on. Thus, `ba$na$*' matches `bananana', etc., with any (zero or more) number of `na' strings. 3. To mark a matched substring for future reference. This last application is not a consequence of the idea of a parenthetical grouping; it is a separate feature which happens to be assigned as a second meaning to the same `$ ... $' construct because in practice there is no conflict between the two meanings. Here is an explanation: `\DIGIT' after the end of a `$ ... $' construct, the matcher remembers the beginning and end of the text matched by that construct. Then, later on in the regular expression, you can use `\' followed by DIGIT to mean "match the same text matched the DIGIT'th time by the `$ ... $' construct." The strings matching the first nine `$ ... $' constructs appearing in a regular expression are assigned numbers 1 through 9 in order that the open-parentheses appear in the regular expression. `\1' through `\9' may be used to refer to the text matched by the corresponding `$ ... $' construct. For example, `$.*$\1' matches any newline-free string that is composed of two identical halves. The `$.*$' matches the first half, which may be anything, but the `\1' that follows must match the same exact text. `\`' matches the empty string, provided it is at the beginning of the buffer. `\'' matches the empty string, provided it is at the end of the buffer. `\b' matches the empty string, provided it is at the beginning or end of a word. Thus, `\bfoo\b' matches any occurrence of `foo' as a separate word. `\bballs?\b' matches `ball' or `balls' as a separate word. `\B' matches the empty string, provided it is not at the beginning or end of a word. `\<' matches the empty string, provided it is at the beginning of a word. `\>' matches the empty string, provided it is at the end of a word. `\w' matches any word-constituent character. The editor syntax table determines which characters these are. `\W' matches any character that is not a word-constituent. `\sCODE' matches any character whose syntax is CODE. CODE is a character which represents a syntax code: thus, `w' for word constituent, `-' for whitespace, `(' for open-parenthesis, etc. *Note Syntax::. `\SCODE' matches any character whose syntax is not CODE. Here is a complicated regexp used by Emacs to recognize the end of a sentence together with any whitespace that follows. It is given in Lisp syntax to enable you to distinguish the spaces from the tab characters. In Lisp syntax, the string constant begins and ends with a double-quote. `\"' stands for a double-quote as part of the regexp, `\\' for a backslash as part of the regexp, `\t' for a tab and `\n' for a newline. "[.?!][]\"')]*\$$\\|\t\\| \$[ \t\n]*" This regexp contains four parts: a character set matching period, `?' or `!'; a character set matching close-brackets, quotes or parentheses, repeated any number of times; an alternative in backslash-parentheses that matches end-of-line, a tab or two spaces; and a character set matching whitespace characters, repeated any number of times.