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GNU Info File | 1994-08-02 | 48.5 KB | 1,155 lines

This is Info file ../info/emacs, produced by Makeinfo-1.54 from the input file emacs.texi. File: emacs, Node: Fill Prefix, Prev: Fill Commands, Up: Filling The Fill Prefix --------------- To fill a paragraph in which each line starts with a special marker (which might be a few spaces, giving an indented paragraph), use the "fill prefix" feature. The fill prefix is a string which Emacs expects every line to start with, and which is not included in filling. `C-x .' Set the fill prefix (`set-fill-prefix'). `M-q' Fill a paragraph using current fill prefix (`fill-paragraph'). `M-x fill-individual-paragraphs' Fill the region, considering each change of indentation as starting a new paragraph. `M-x fill-nonuniform-paragraphs' Fill the region, considering only paragraph-separator lines as starting a new paragraph. To specify a fill prefix, move to a line that starts with the desired prefix, put point at the end of the prefix, and give the command `C-x .' (`set-fill-prefix'). That's a period after the `C-x'. To turn off the fill prefix, specify an empty prefix: type `C-x .' with point at the beginning of a line. When a fill prefix is in effect, the fill commands remove the fill prefix from each line before filling and insert it on each line after filling. The fill prefix is also inserted on new lines made automatically by Auto Fill mode. Lines that do not start with the fill prefix are considered to start paragraphs, both in `M-q' and the paragraph commands; this is just right if you are using paragraphs with hanging indentation (every line indented except the first one). Lines which are blank or indented once the prefix is removed also separate or start paragraphs; this is what you want if you are writing multi-paragraph comments with a comment delimiter on each line. For example, if `fill-column' is 40 and you set the fill prefix to `;; ', then `M-q' in the following text ;; This is an ;; example of a paragraph ;; inside a Lisp-style comment. produces this: ;; This is an example of a paragraph ;; inside a Lisp-style comment. The `C-o' command inserts the fill prefix on new lines it creates, when you use it at the beginning of a line (*note Blank Lines::.). Conversely, the command `M-^' deletes the prefix (if it occurs) after the newline that it deletes (*note Indentation::.). You can use `M-x fill-individual-paragraphs' to set the fill prefix for each paragraph automatically. This command divides the region into paragraphs, treating every change in the amount of indentation as the start of a new paragraph, and fills each of these paragraphs. Thus, all the lines in one "paragraph" have the same amount of indentation. That indentation serves as the fill prefix for that paragraph. `M-x fill-nonuniform-paragraphs' is a similar command that divides the region into paragraphs in a different way. It considers only paragraph-separating lines (as defined by `paragraph-separate') as starting a new paragraph. Since this means that the lines of one paragraph may have different amounts of indentation, the fill prefix used is the smallest amount of indentation of any of the lines of the paragraph. The fill prefix is stored in the variable `fill-prefix'. Its value is a string, or `nil' when there is no fill prefix. This is a per-buffer variable; altering the variable affects only the current buffer, but there is a default value which you can change as well. *Note Locals::. File: emacs, Node: Case, Next: Text Mode, Prev: Filling, Up: Text Case Conversion Commands ======================== Emacs has commands for converting either a single word or any arbitrary range of text to upper case or to lower case. `M-l' Convert following word to lower case (`downcase-word'). `M-u' Convert following word to upper case (`upcase-word'). `M-c' Capitalize the following word (`capitalize-word'). `C-x C-l' Convert region to lower case (`downcase-region'). `C-x C-u' Convert region to upper case (`upcase-region'). The word conversion commands are the most useful. `M-l' (`downcase-word') converts the word after point to lower case, moving past it. Thus, repeating `M-l' converts successive words. `M-u' (`upcase-word') converts to all capitals instead, while `M-c' (`capitalize-word') puts the first letter of the word into upper case and the rest into lower case. All these commands convert several words at once if given an argument. They are especially convenient for converting a large amount of text from all upper case to mixed case, because you can move through the text using `M-l', `M-u' or `M-c' on each word as appropriate, occasionally using `M-f' instead to skip a word. When given a negative argument, the word case conversion commands apply to the appropriate number of words before point, but do not move point. This is convenient when you have just typed a word in the wrong case: you can give the case conversion command and continue typing. If a word case conversion command is given in the middle of a word, it applies only to the part of the word which follows point. This is just like what `M-d' (`kill-word') does. With a negative argument, case conversion applies only to the part of the word before point. The other case conversion commands are `C-x C-u' (`upcase-region') and `C-x C-l' (`downcase-region'), which convert everything between point and mark to the specified case. Point and mark do not move. The region case conversion commands `upcase-region' and `downcase-region' are normally disabled. This means that they ask for confirmation if you try to use them. When you confirm, you may enable the command, which means it will not ask for confirmation again. *Note Disabling::. File: emacs, Node: Text Mode, Next: Outline Mode, Prev: Case, Up: Text Text Mode ========= When you edit files of text in a human language, it's more convenient to use Text mode rather than Fundamental mode. Invoke `M-x text-mode' to enter Text mode. In Text mode, TAB runs the function `tab-to-tab-stop', which allows you to use arbitrary tab stops set with `M-x edit-tab-stops' (*note Tab Stops::.). Features concerned with comments in programs are turned off except when explicitly invoked. The syntax table is changed so that periods are not considered part of a word, while apostrophes, backspaces and underlines are. A similar variant mode is Indented Text mode, intended for editing text in which most lines are indented. This mode defines TAB to run `indent-relative' (*note Indentation::.), and makes Auto Fill indent the lines it creates. The result is that normally a line made by Auto Filling, or by LFD, is indented just like the previous line. In Indented Text mode, only blank lines separate paragraphs--indented lines continue the current paragraph. Use `M-x indented-text-mode' to select this mode. Text mode, and all the modes based on it, define `M-TAB' as the command `ispell-complete-word', which performs completion of the partial word in the buffer before point, using the spelling dictionary as the space of possible words. *Note Spelling::. Entering Text mode or Indented Text mode runs the hook `text-mode-hook'. Other major modes related to Text mode also run this hook, followed by hooks of their own; this includes Nroff mode, TeX mode, Outline mode and Mail mode. Hook functions on `text-mode-hook' can look at the value of `major-mode' to see which of these modes is actually being entered. *Note Hooks::. * Menu: Emacs provides two other modes for editing text that is to be passed through a text formatter to produce fancy formatted printed output. * Nroff Mode:: The major mode for editing input to the formatter nroff. * TeX Mode:: The major modes for editing input to the formatter TeX. Another mode is used for editing outlines. It allows you to view the text at various levels of detail. You can view either the outline headings alone or both headings and text; you can also hide some of the headings at lower levels from view to make the high level structure more visible. * Outline Mode::The major mode for editing outlines. File: emacs, Node: Outline Mode, Next: TeX Mode, Prev: Text Mode, Up: Text Outline Mode ============ Outline mode is a major mode much like Text mode but intended for editing outlines. It allows you to make parts of the text temporarily invisible so that you can see just the overall structure of the outline. Type `M-x outline-mode' to switch to Outline mode as the major mode of the current buffer. Type `M-x outline-minor-mode' to enable Outline mode as a minor mode in the current buffer. When Outline minor mode is enabled, the `C-c' commands of Outline mode replace those of the major mode. When a line is invisible in outline mode, it does not appear on the screen. The screen appears exactly as if the invisible line were deleted, except that an ellipsis (three periods in a row) appears at the end of the previous visible line (only one ellipsis no matter how many invisible lines follow). All editing commands treat the text of the invisible line as part of the previous visible line. For example, `C-n' moves onto the next visible line. Killing an entire visible line, including its terminating newline, really kills all the following invisible lines along with it; yanking it all back yanks the invisible lines and they remain invisible. Entering Outline mode runs the hook `text-mode-hook' followed by the hook `outline-mode-hook' (*note Hooks::.). * Menu: * Format: Outline Format. What the text of an outline looks like. * Motion: Outline Motion. Special commands for moving through outlines. * Visibility: Outline Visibility. Commands to control what is visible. File: emacs, Node: Outline Format, Next: Outline Motion, Up: Outline Mode Format of Outlines ------------------ Outline mode assumes that the lines in the buffer are of two types: "heading lines" and "body lines". A heading line represents a topic in the outline. Heading lines start with one or more stars; the number of stars determines the depth of the heading in the outline structure. Thus, a heading line with one star is a major topic; all the heading lines with two stars between it and the next one-star heading are its subtopics; and so on. Any line that is not a heading line is a body line. Body lines belong with the preceding heading line. Here is an example: * Food This is the body, which says something about the topic of food. ** Delicious Food This is the body of the second-level header. ** Distasteful Food This could have a body too, with several lines. *** Dormitory Food * Shelter A second first-level topic with its header line. A heading line together with all following body lines is called collectively an "entry". A heading line together with all following deeper heading lines and their body lines is called a "subtree". You can customize the criterion for distinguishing heading lines by setting the variable `outline-regexp'. Any line whose beginning has a match for this regexp is considered a heading line. Matches that start within a line (not at the beginning) do not count. The length of the matching text determines the level of the heading; longer matches make a more deeply nested level. Thus, for example, if a text formatter has commands `@chapter', `@section' and `@subsection' to divide the document into chapters and sections, you could make those lines count as heading lines by setting `outline-regexp' to `"@chap\\|@\$sub\$*section"'. Note the trick: the two words `chapter' and `section' are equally long, but by defining the regexp to match only `chap' we ensure that the length of the text matched on a chapter heading is shorter, so that Outline mode will know that sections are contained in chapters. This works as long as no other command starts with `@chap'. Outline mode makes a line invisible by changing the newline before it into an ASCII control-M (code 015). Most editing commands that work on lines treat an invisible line as part of the previous line because, strictly speaking, it *is* part of that line, since there is no longer a newline in between. When you save the file in Outline mode, control-M characters are saved as newlines, so the invisible lines become ordinary lines in the file. But saving does not change the visibility status of a line inside Emacs. File: emacs, Node: Outline Motion, Next: Outline Visibility, Prev: Outline Format, Up: Outline Mode Outline Motion Commands ----------------------- There are some special motion commands in Outline mode that move backward and forward to heading lines. `C-c C-n' Move point to the next visible heading line (`outline-next-visible-heading'). `C-c C-p' Move point to the previous visible heading line (`outline-previous-visible-heading'). `C-c C-f' Move point to the next visible heading line at the same level as the one point is on (`outline-forward-same-level'). `C-c C-b' Move point to the previous visible heading line at the same level (`outline-backward-same-level'). `C-c C-u' Move point up to a lower-level (more inclusive) visible heading line (`outline-up-heading'). `C-c C-n' (`next-visible-heading') moves down to the next heading line. `C-c C-p' (`previous-visible-heading') moves similarly backward. Both accept numeric arguments as repeat counts. The names emphasize that invisible headings are skipped, but this is not really a special feature. All editing commands that look for lines ignore the invisible lines automatically. More powerful motion commands understand the level structure of headings. `C-c C-f' (`outline-forward-same-level') and `C-c C-b' (`outline-backward-same-level') move from one heading line to another visible heading at the same depth in the outline. `C-c C-u' (`outline-up-heading') moves backward to another heading that is less deeply nested. File: emacs, Node: Outline Visibility, Prev: Outline Motion, Up: Outline Mode Outline Visibility Commands --------------------------- The other special commands of outline mode are used to make lines visible or invisible. Their names all start with `hide' or `show'. Most of them fall into pairs of opposites. They are not undoable; instead, you can undo right past them. Making lines visible or invisible is simply not recorded by the undo mechanism. `M-x hide-body' Make all body lines in the buffer invisible. `M-x show-all' Make all lines in the buffer visible. `C-c C-h' Make everything under this heading invisible, not including this heading itself (`hide-subtree'). `C-c C-s' Make everything under this heading visible, including body, subheadings, and their bodies (`show-subtree'). `M-x hide-leaves' Make the body of this heading line, and of all its subheadings, invisible. `M-x show-branches' Make all subheadings of this heading line, at all levels, visible. `C-c C-i' Make immediate subheadings (one level down) of this heading line visible (`show-children'). `M-x hide-entry' Make this heading line's body invisible. `M-x show-entry' Make this heading line's body visible. Two commands that are exact opposites are `M-x hide-entry' and `M-x show-entry'. They are used with point on a heading line, and apply only to the body lines of that heading. The subtopics and their bodies are not affected. Two more powerful opposites are `C-c C-h' (`hide-subtree') and `C-c C-s' (`show-subtree'). Both expect to be used when point is on a heading line, and both apply to all the lines of that heading's "subtree": its body, all its subheadings, both direct and indirect, and all of their bodies. In other words, the subtree contains everything following this heading line, up to and not including the next heading of the same or higher rank. Intermediate between a visible subtree and an invisible one is having all the subheadings visible but none of the body. There are two commands for doing this, depending on whether you want to hide the bodies or make the subheadings visible. They are `M-x hide-leaves' and `M-x show-branches'. A little weaker than `show-branches' is `C-c C-i' (`show-children'). It makes just the direct subheadings visible--those one level down. Deeper subheadings remain invisible, if they were invisible. Two commands have a blanket effect on the whole file. `M-x hide-body' makes all body lines invisible, so that you see just the outline structure. `M-x show-all' makes all lines visible. These commands can be thought of as a pair of opposites even though `M-x show-all' applies to more than just body lines. You can turn off the use of ellipses at the ends of visible lines by setting `selective-display-ellipses' to `nil'. Then there is no visible indication of the presence of invisible lines. File: emacs, Node: TeX Mode, Next: Nroff Mode, Prev: Outline Mode, Up: Text TeX Mode ======== TeX is a powerful text formatter written by Donald Knuth; it is also free, like GNU Emacs. LaTeX is a simplified input format for TeX, implemented by TeX macros; it comes with TeX. SliTeX is a special form of LaTeX. Emacs has a special TeX mode for editing TeX input files. It provides facilities for checking the balance of delimiters and for invoking TeX on all or part of the file. TeX mode has three variants, Plain TeX mode, LaTeX mode, and SliTeX mode (these three distinct major modes differ only slightly). They are designed for editing the three different formats. The command `M-x tex-mode' looks at the contents of the buffer to determine whether the contents appear to be either LaTeX input or SliTeX input; it then selects the appropriate mode. If it can't tell which is right (e.g., the buffer is empty), the variable `tex-default-mode' controls which mode is used. When `M-x tex-mode' does not guess right, you can use the commands `M-x plain-tex-mode', `M-x latex-mode', and `M-x slitex-mode' to select explicitly the particular variants of TeX mode. * Menu: * Editing: TeX Editing. Special commands for editing in TeX mode. * LaTeX: LaTeX Editing. Additional commands for LaTeX input files. * Printing: TeX Print. Commands for printing part of a file with TeX. * Getting: TeX Distrib. Getting the latest Unix TeX distribution. File: emacs, Node: TeX Editing, Next: LaTeX Editing, Up: TeX Mode TeX Editing Commands -------------------- Here are the special commands provided in TeX mode for editing the text of the file. `"' Insert, according to context, either ```' or `"' or `''' (`tex-insert-quote'). `LFD' Insert a paragraph break (two newlines) and check the previous paragraph for unbalanced braces or dollar signs (`tex-terminate-paragraph'). `M-x validate-tex-region' Check each paragraph in the region for unbalanced braces or dollar signs. `C-c {' Insert `{}' and position point between them (`tex-insert-braces'). `C-c }' Move forward past the next unmatched close brace (`up-list'). In TeX, the character `"' is not normally used; we use ```' to start a quotation and `''' to end one. To make editing easier under this formatting convention, TeX mode overrides the normal meaning of the key `"' with a command that inserts a pair of single-quotes or backquotes (`tex-insert-quote'). To be precise, this command inserts ```' after whitespace or an open brace, `"' after a backslash, and `''' after any other character. If you need the character `"' itself in unusual contexts, use `C-q' to insert it. Also, `"' with a numeric argument always inserts that number of `"' characters. In TeX mode, `$' has a special syntax code which attempts to understand the way TeX math mode delimiters match. When you insert a `$' that is meant to exit math mode, the position of the matching `$' that entered math mode is displayed for a second. This is the same feature that displays the open brace that matches a close brace that is inserted. However, there is no way to tell whether a `$' enters math mode or leaves it; so when you insert a `$' that enters math mode, the previous `$' position is shown as if it were a match, even though they are actually unrelated. TeX uses braces as delimiters that must match. Some users prefer to keep braces balanced at all times, rather than inserting them singly. Use `C-c {' (`tex-insert-braces') to insert a pair of braces. It leaves point between the two braces so you can insert the text that belongs inside. Afterward, use the command `C-c }' (`up-list') to move forward past the close brace. There are two commands for checking the matching of braces. LFD (`tex-terminate-paragraph') checks the paragraph before point, and inserts two newlines to start a new paragraph. It prints a message in the echo area if any mismatch is found. `M-x validate-tex-region' checks a region, paragraph by paragraph. When it finds a paragraph that contains a mismatch, it displays point at the beginning of the paragraph for a few seconds and pushes a mark at that spot. Scanning continues until the whole buffer has been checked or until you type another key. The positions of the last several paragraphs with mismatches can be found in the mark ring (*note Mark Ring::.). Note that Emacs commands count square brackets and parentheses in TeX mode, not just braces. This is not strictly correct for the purpose of checking TeX syntax. However, parentheses and square brackets are likely to be used in text as matching delimiters and it is useful for the various motion commands and automatic match display to work with them. File: emacs, Node: LaTeX Editing, Next: TeX Print, Prev: TeX Editing, Up: TeX Mode LaTeX Editing Commands ---------------------- LaTeX mode provides a few extra features not applicable to plain TeX. `C-c C-o' Insert `\begin' and `\end' for LaTeX block and position point on a line between them. (`tex-latex-block'). `C-c C-e' Close the last unended block for LaTeX (`tex-close-latex-block'). In LaTeX input, `\begin' and `\end' commands are used to group blocks of text. To insert a `\begin' and a matching `\end' (on a new line following the `\begin'), use `C-c C-o' (`tex-latex-block'). A blank line is inserted between the two, and point is left there. Emacs knows all of the standard LaTeX block names and will permissively complete a partially entered block name (*note Completion::.). You can add your own list of block names to those known by Emacs with the variable `latex-block-names'. For example, to add `theorem', `corollary', and `proof', include the line (setq latex-block-names '("theorem" "corollary" "proof")) to your `.emacs' file. In LaTeX input, `\begin' and `\end' commands must balance. You can use `C-c C-e' (`tex-close-latex-block') to insert automatically a matching `\end' to match the last unmatched `\begin'. The `\end' will be indented to match the corresponding `\begin'. The `\end' will be followed by a newline if point is at the beginning of a line. File: emacs, Node: TeX Print, Next: TeX Distrib, Prev: LaTeX Editing, Up: TeX Mode TeX Printing Commands --------------------- You can invoke TeX as an inferior of Emacs on either the entire contents of the buffer or just a region at a time. Running TeX in this way on just one chapter is a good way to see what your changes look like without taking the time to format the entire file. `C-c C-r' Invoke TeX on the current region, together with the buffer's header (`tex-region'). `C-c C-b' Invoke TeX on the entire current buffer (`tex-buffer'). `C-c TAB' Invoke BibTeX on the current file (`tex-bibtex-file'). `C-c C-f' Invoke TeX on the current file (`tex-file'). `C-c C-l' Recenter the window showing output from the inferior TeX so that the last line can be seen (`tex-recenter-output-buffer'). `C-c C-k' Kill the TeX subprocess (`tex-kill-job'). `C-c C-p' Print the output from the last `C-c C-r', `C-c C-b', or `C-c C-f' command (`tex-print'). `C-c C-v' Preview the output from the last `C-c C-r', `C-c C-b', or `C-c C-f' command (`tex-view'). `C-c C-q' Show the printer queue (`tex-show-print-queue'). You can pass the current buffer through an inferior TeX by means of `C-c C-b' (`tex-buffer'). The formatted output appears in a temporary; to print it, type `C-c C-p' (`tex-print'). Afterward use `C-c C-q' (`tex-show-print-queue') to view the progress of your output towards being printed. If your terminal has the ability to display TeX output files, you can preview the output on the terminal with `C-c C-v' (`tex-view'). You can specify the directory to use for running TeX by setting the variable `tex-directory'. `"."' is the default value. If your environment variable `TEXINPUTS' contains relative directory names, or if your files contains `\input' commands with relative file names, then `tex-directory' *must* be `"."' or you will get the wrong results. Otherwise, it is safe to specify some other directory, such as `/tmp'. If you want to specify which shell commands are used in the inferior TeX, you can do so by setting the values of the variables `tex-run-command', `latex-run-command', `slitex-run-command', `tex-dvi-print-command', `tex-dvi-view-command', and `tex-show-queue-command'. You *must* set the value of `tex-dvi-view-command' for your particular terminal; this variable has no default value. The other variables have default values that may (or may not) be appropriate for your system. Normally, the file name given to these commands comes at the end of the command string; for example, `latex FILENAME'. In some cases, however, the file name needs to be embedded in the command; an example is when you need to provide the file name as an argument to one command whose output is piped to another. You can specify where to put the file name with `*' in the command string. For example, (setq tex-dvi-print-command "dvips -f * | lpr") The terminal output from TeX, including any error messages, appears in a buffer called `*tex-shell*'. If TeX gets an error, you can switch to this buffer and feed it input (this works as in Shell mode; *note Interactive Shell::.). Without switching to this buffer you can scroll it so that its last line is visible by typing `C-c C-l'. Type `C-c C-k' (`tex-kill-job') to kill the TeX process if you see that its output is no longer useful. Using `C-c C-b' or `C-c C-r' also kills any TeX process still running. You can also pass an arbitrary region through an inferior TeX by typing `C-c C-r' (`tex-region'). This is tricky, however, because most files of TeX input contain commands at the beginning to set parameters and define macros, without which no later part of the file will format correctly. To solve this problem, `C-c C-r' allows you to designate a part of the file as containing essential commands; it is included before the specified region as part of the input to TeX. The designated part of the file is called the "header". To indicate the bounds of the header in Plain TeX mode, you insert two special strings in the file. Insert `%**start of header' before the header, and `%**end of header' after it. Each string must appear entirely on one line, but there may be other text on the line before or after. The lines containing the two strings are included in the header. If `%**start of header' does not appear within the first 100 lines of the buffer, `C-c C-r' assumes that there is no header. In LaTeX mode, the header begins with `\documentstyle' and ends with `\begin{document}'. These are commands that LaTeX requires you to use in any case, so nothing special needs to be done to identify the header. The commands (`tex-buffer') and (`tex-region') do all of their work in a temporary directory, and do not have available any of the auxiliary files needed by TeX for cross-references; these commands are generally not suitable for running the final copy in which all of the cross-references need to be correct. When you want the auxiliary files, use `C-c C-f' (`tex-file') which runs TeX on the current buffer's file, in that file's directory. Before TeX runs, you will be asked about saving any modified buffers. Generally, you need to use (`tex-file') twice to get cross-references correct. For LaTeX files, you can use BibTeX to process the auxiliary file for the current buffer's file. BibTeX looks up bibliographic citations in a data base and prepares the cited references for the bibliography section. The command `C-c TAB' (`tex-bibtex-file') runs the shell command (`tex-bibtex-command') to produce a `.bbl' file for the current buffer's file. Generally, you need to do `C-c C-f' (`tex-file') once to generate the `.aux' file, then do `C-c TAB' (`tex-bibtex-file'), and then repeat `C-c C-f' (`tex-file') twice more to get the cross-references correct. Entering any kind of TeX mode runs the hooks `text-mode-hook' and `tex-mode-hook'. Then it runs either `plain-tex-mode-hook' or `latex-mode-hook', whichever is appropriate. For SliTeX files, it calls `slitex-mode-hook'. Starting the TeX shell runs the hook `tex-shell-hook'. *Note Hooks::. File: emacs, Node: TeX Distrib, Prev: TeX Print, Up: TeX Mode Unix TeX Distribution --------------------- TeX for Unix systems can be obtained from the University of Washington for a distribution fee. To order a full distribution, send $200.00 for a 1/2-inch 9-track 1600 bpi (tar or cpio) tape reel, or $210.00 for a 1/4-inch 4-track QIC-24 (tar or cpio) cartridge, payable to the University of Washington to: Northwest Computing Support Center DR-10, Thomson Hall 35 University of Washington Seattle, Washington 98195 Purchase orders are acceptable, but there is an extra charge of $10.00, to pay for processing charges. For overseas orders please add $20.00 to the base cost for shipment via air parcel post, or $30.00 for shipment via courier. The normal distribution is a tar tape, blocked 20, 1600 bpi, on an industry standard 2400 foot half-inch reel. The physical format for the 1/4 inch streamer cartridges uses QIC-11, 8000 bpi, 4-track serpentine recording for the SUN. Also, System V tapes can be written in cpio format, blocked 5120 bytes, ASCII headers. File: emacs, Node: Nroff Mode, Prev: TeX Mode, Up: Text Nroff Mode ========== Nroff mode is a mode like Text mode but modified to handle nroff commands present in the text. Invoke `M-x nroff-mode' to enter this mode. It differs from Text mode in only a few ways. All nroff command lines are considered paragraph separators, so that filling will never garble the nroff commands. Pages are separated by `.bp' commands. Comments start with backslash-doublequote. Also, three special commands are provided that are not in Text mode: `M-n' Move to the beginning of the next line that isn't an nroff command (`forward-text-line'). An argument is a repeat count. `M-p' Like `M-n' but move up (`backward-text-line'). `M-?' Prints in the echo area the number of text lines (lines that are not nroff commands) in the region (`count-text-lines'). The other feature of Nroff mode is that you can turn on Electric Nroff mode. This is a minor mode that you can turn on or off with `M-x electric-nroff-mode' (*note Minor Modes::.). When the mode is on, each time you use RET to end a line that contains an nroff command that opens a kind of grouping, the matching nroff command to close that grouping is automatically inserted on the following line. For example, if you are at the beginning of a line and type `. ( b RET', this inserts the matching command `.)b' on a new line following point. Entering Nroff mode runs the hook `text-mode-hook', followed by the hook `nroff-mode-hook' (*note Hooks::.). File: emacs, Node: Programs, Next: Building, Prev: Text, Up: Top Editing Programs **************** Emacs has many commands designed to understand the syntax of programming languages such as Lisp and C. These commands can * Move over or kill balanced expressions or "sexps" (*note Lists::.). * Move over or mark top-level expressions--"defuns", in Lisp; functions, in C (*note Defuns::.). * Show how parentheses balance (*note Matching::.). * Insert, kill or align comments (*note Comments::.). * Follow the usual indentation conventions of the language (*note Program Indent::.). The commands for words, sentences and paragraphs are very useful in editing code even though their canonical application is for editing human language text. Most symbols contain words (*note Words::.); sentences can be found in strings and comments (*note Sentences::.). Paragraphs per se don't exist in code, but the paragraph commands are useful anyway, because programming language major modes define paragraphs to begin and end at blank lines (*note Paragraphs::.). Judicious use of blank lines to make the program clearer will also provide interesting chunks of text for the paragraph commands to work on. The selective display feature is useful for looking at the overall structure of a function (*note Selective Display::.). This feature causes only the lines that are indented less than a specified amount to appear on the screen. * Menu: * Program Modes:: Major modes for editing programs. * Lists:: Expressions with balanced parentheses. * List Commands:: The commands for working with list and sexps. * Defuns:: Each program is made up of separate functions. There are editing commands to operate on them. * Program Indent:: Adjusting indentation to show the nesting. * Matching:: Insertion of a close-delimiter flashes matching open. * Comments:: Inserting, killing, and aligning comments. * Balanced Editing:: Inserting two matching parentheses at once, etc. * Symbol Completion:: Completion on symbol names of your program or language. * Documentation:: Getting documentation of functions you plan to call. * Change Log:: Maintaining a change history for your program. * Tags:: Go direct to any function in your program in one command. Tags remembers which file it is in. * Emerge:: A convenient way of merging two versions of a program. * C Mode:: Special commands of C mode (and C++ mode). * Fortran:: Fortran mode and its special features. * Asm Mode:: Asm mode and its special features. File: emacs, Node: Program Modes, Next: Lists, Up: Programs Major Modes for Programming Languages ===================================== Emacs also has major modes for the programming languages Lisp, Scheme (a variant of Lisp), Awk, C, C++, Perl, Icon, Fortran and Muddle (another variant of Lisp). There is also a major mode for makefiles, called Makefile mode. Ideally, a major mode should be implemented for each programming language that you might want to edit with Emacs; but often the mode for one language can serve for other syntactically similar languages. The language modes that exist are those that someone decided to take the trouble to write. There are several forms of Lisp mode, which differ in the way they interface to Lisp execution. *Note Executing Lisp::. Each of the programming language modes defines the TAB key to run an indentation function that knows the indentation conventions of that language and updates the current line's indentation accordingly. For example, in C mode TAB is bound to `c-indent-line'. LFD is normally defined to do RET followed by TAB; thus, it too indents in a mode-specific fashion. In most programming languages, indentation is likely to vary from line to line. So the major modes for those languages rebind DEL to treat a tab as if it were the equivalent number of spaces (using the command `backward-delete-char-untabify'). This makes it possible to rub out indentation one column at a time without worrying whether it is made up of spaces or tabs. Use `C-b C-d' to delete a tab character before point, in these modes. Programming language modes define paragraphs to be separated only by blank lines, so that the paragraph commands remain useful. Auto Fill mode, if enabled in a programming language major mode, indents the new lines which it creates. Turning on a major mode runs a normal hook called the "mode hook", which is the value of a Lisp variable. For example, turning on C mode runs the hook `c-mode-hook'. Mode hook variables for other programming language modes include `lisp-mode-hook', `emacs-lisp-mode-hook', `lisp-interaction-mode-hook', `scheme-mode-hook' and `muddle-mode-hook'. *Note Hooks::. File: emacs, Node: Lists, Next: List Commands, Prev: Program Modes, Up: Programs Lists and Sexps =============== By convention, Emacs keys for dealing with balanced expressions are usually Control-Meta characters. They tend to be analogous in function to their Control and Meta equivalents. These commands are usually thought of as pertaining to expressions in programming languages, but can be useful with any language in which some sort of parentheses exist (including human languages). These commands fall into two classes. Some deal only with "lists" (parenthetical groupings). They see nothing except parentheses, brackets, braces (whichever ones must balance in the language you are working with), and escape characters that might be used to quote those. The other commands deal with expressions or "sexps". The word `sexp' is derived from "s-expression", the ancient term for an expression in Lisp. But in Emacs, the notion of `sexp' is not limited to Lisp. It refers to an expression in whatever language your program is written in. Each programming language has its own major mode, which customizes the syntax tables so that expressions in that language count as sexps. Sexps typically include symbols, numbers, and string constants, as well as anything contained in parentheses, brackets or braces. In languages that use prefix and infix operators, such as C, it is not possible for all expressions to be sexps. For example, C mode does not recognize `foo + bar' as a sexp, even though it *is* a C expression; it recognizes `foo' as one sexp and `bar' as another, with the `+' as punctuation between them. This is a fundamental ambiguity: both `foo + bar' and `foo' are legitimate choices for the sexp to move over if point is at the `f'. Note that `(foo + bar)' is a single sexp in C mode. Some languages have obscure forms of syntax for expressions that nobody has bothered to make Emacs understand properly. File: emacs, Node: List Commands, Next: Defuns, Prev: Lists, Up: Programs List And Sexp Commands ====================== `C-M-f' Move forward over a sexp (`forward-sexp'). `C-M-b' Move backward over a sexp (`backward-sexp'). `C-M-k' Kill sexp forward (`kill-sexp'). `C-M-u' Move up and backward in list structure (`backward-up-list'). `C-M-d' Move down and forward in list structure (`down-list'). `C-M-n' Move forward over a list (`forward-list'). `C-M-p' Move backward over a list (`backward-list'). `C-M-t' Transpose expressions (`transpose-sexps'). `C-M-@' Put mark after following expression (`mark-sexp'). To move forward over a sexp, use `C-M-f' (`forward-sexp'). If the first significant character after point is an opening delimiter (`(' in Lisp; `(', `[' or `{' in C), `C-M-f' moves past the matching closing delimiter. If the character begins a symbol, string, or number, `C-M-f' moves over that. The command `C-M-b' (`backward-sexp') moves backward over a sexp. The detailed rules are like those above for `C-M-f', but with directions reversed. If there are any prefix characters (single-quote, backquote and comma, in Lisp) preceding the sexp, `C-M-b' moves back over them as well. The sexp commands move across comments as if they were whitespace in most modes. `C-M-f' or `C-M-b' with an argument repeats that operation the specified number of times; with a negative argument, it moves in the opposite direction. Killing a sexp at a time can be done with `C-M-k' (`kill-sexp'). `C-M-k' kills the characters that `C-M-f' would move over. The "list commands" move over lists like the sexp commands but skip blithely over any number of other kinds of sexps (symbols, strings, etc). They are `C-M-n' (`forward-list') and `C-M-p' (`backward-list'). The main reason they are useful is that they usually ignore comments (since the comments usually do not contain any lists). `C-M-n' and `C-M-p' stay at the same level in parentheses, when that's possible. To move *up* one (or N) levels, use `C-M-u' (`backward-up-list'). `C-M-u' moves backward up past one unmatched opening delimiter. A positive argument serves as a repeat count; a negative argument reverses direction of motion and also requests repetition, so it moves forward and up one or more levels. To move *down* in list structure, use `C-M-d' (`down-list'). In Lisp mode, where `(' is the only opening delimiter, this is nearly the same as searching for a `('. An argument specifies the number of levels of parentheses to go down. A somewhat random-sounding command which is nevertheless handy is `C-M-t' (`transpose-sexps'), which drags the previous sexp across the next one. An argument serves as a repeat count, and a negative argument drags backwards (thus canceling out the effect of `C-M-t' with a positive argument). An argument of zero, rather than doing nothing, transposes the sexps ending after point and the mark. To make the region be the next sexp in the buffer, use `C-M-@' (`mark-sexp') which sets mark at the same place that `C-M-f' would move to. `C-M-@' takes arguments like `C-M-f'. In particular, a negative argument is useful for putting the mark at the beginning of the previous sexp. The list and sexp commands' understanding of syntax is completely controlled by the syntax table. Any character can, for example, be declared to be an opening delimiter and act like an open parenthesis. *Note Syntax::. File: emacs, Node: Defuns, Next: Program Indent, Prev: List Commands, Up: Programs Defuns ====== In Emacs, a parenthetical grouping at the top level in the buffer is called a "defun". The name derives from the fact that most top-level lists in a Lisp file are instances of the special form `defun', but any top-level parenthetical grouping counts as a defun in Emacs parlance regardless of what its contents are, and regardless of the programming language in use. For example, in C, the body of a function definition is a defun. `C-M-a' Move to beginning of current or preceding defun (`beginning-of-defun'). `C-M-e' Move to end of current or following defun (`end-of-defun'). `C-M-h' Put region around whole current or following defun (`mark-defun'). The commands to move to the beginning and end of the current defun are `C-M-a' (`beginning-of-defun') and `C-M-e' (`end-of-defun'). If you wish to operate on the current defun, use `C-M-h' (`mark-defun') which puts point at the beginning and mark at the end of the current or next defun. For example, this is the easiest way to get ready to move the defun to a different place in the text. In C mode, `C-M-h' runs the function `mark-c-function', which is almost the same as `mark-defun'; the difference is that it backs up over the argument declarations, function name and returned data type so that the entire C function is inside the region. *Note Marking Objects::. Emacs assumes that any open-parenthesis found in the leftmost column is the start of a defun. Therefore, *never put an open-parenthesis at the left margin in a Lisp file unless it is the start of a top level list. Never put an open-brace or other opening delimiter at the beginning of a line of C code unless it starts the body of a function.* The most likely problem case is when you want an opening delimiter at the start of a line inside a string. To avoid trouble, put an escape character (`\', in C and Emacs Lisp, `/' in some other Lisp dialects) before the opening delimiter. It will not affect the contents of the string. In the remotest past, the original Emacs found defuns by moving upward a level of parentheses until there were no more levels to go up. This always required scanning all the way back to the beginning of the buffer, even for a small function. To speed up the operation, Emacs was changed to assume that any `(' (or other character assigned the syntactic class of opening-delimiter) at the left margin is the start of a defun. This heuristic is nearly always right and avoids the costly scan; however, it mandates the convention described above. File: emacs, Node: Program Indent, Next: Matching, Prev: Defuns, Up: Programs Indentation for Programs ======================== The best way to keep a program properly indented is to use Emacs to re-indent it as you change it. Emacs has commands to indent properly either a single line, a specified number of lines, or all of the lines inside a single parenthetical grouping. * Menu: * Basic Indent:: Indenting a single line. * Multi-line Indent:: Commands to reindent many lines at once. * Lisp Indent:: Specifying how each Lisp function should be indented. * C Indent:: Choosing an indentation style for C code. File: emacs, Node: Basic Indent, Next: Multi-line Indent, Up: Program Indent Basic Program Indentation Commands ---------------------------------- `TAB' Adjust indentation of current line. `LFD' Equivalent to RET followed by TAB (`newline-and-indent'). The basic indentation command is TAB, which gives the current line the correct indentation as determined from the previous lines. The function that TAB runs depends on the major mode; it is `lisp-indent-line' in Lisp mode, `c-indent-line' in C mode, etc. These functions understand different syntaxes for different languages, but they all do about the same thing. TAB in any programming language major mode inserts or deletes whitespace at the beginning of the current line, independent of where point is in the line. If point is inside the whitespace at the beginning of the line, TAB leaves it at the end of that whitespace; otherwise, TAB leaves point fixed with respect to the characters around it. Use `C-q TAB' to insert a tab at point. When entering a large amount of new code, use LFD (`newline-and-indent'), which is equivalent to a RET followed by a TAB. LFD creates a blank line, and then gives it the appropriate indentation. TAB indents the second and following lines of the body of a parenthetical grouping each under the preceding one; therefore, if you alter one line's indentation to be nonstandard, the lines below will tend to follow it. This is the right behavior in cases where the standard result of TAB is unaesthetic. Remember that an open-parenthesis, open-brace or other opening delimiter at the left margin is assumed by Emacs (including the indentation routines) to be the start of a function. Therefore, you must never have an opening delimiter in column zero that is not the beginning of a function, not even inside a string. This restriction is vital for making the indentation commands fast; you must simply accept it. *Note Defuns::, for more information on this. File: emacs, Node: Multi-line Indent, Next: Lisp Indent, Prev: Basic Indent, Up: Program Indent Indenting Several Lines ----------------------- When you wish to re-indent several lines of code which have been altered or moved to a different level in the list structure, you have several commands available. `C-M-q' Re-indent all the lines within one list (`indent-sexp'). `C-u TAB' Shift an entire list rigidly sideways so that its first line is properly indented. `C-M-\' Re-indent all lines in the region (`indent-region'). You can re-indent the contents of a single list by positioning point before the beginning of it and typing `C-M-q' (`indent-sexp' in Lisp mode, `indent-c-exp' in C mode; also bound to other suitable commands in other modes). The indentation of the line the sexp starts on is not changed; therefore, only the relative indentation within the list, and not its position, is changed. To correct the position as well, type a TAB before the `C-M-q'. If the relative indentation within a list is correct but the indentation of its beginning is not, go to the line the list begins on and type `C-u TAB'. When TAB is given a numeric argument, it moves all the lines in the grouping starting on the current line sideways the same amount that the current line moves. It is clever, though, and does not move lines that start inside strings, or C preprocessor lines when in C mode. Another way to specify the range to be re-indented is with point and mark. The command `C-M-\' (`indent-region') applies TAB to every line whose first character is between point and mark.