This is Info file ../../info/lispref.info, produced by Makeinfo version 1.68 from the input file lispref.texi. Edition History: GNU Emacs Lisp Reference Manual Second Edition (v2.01), May 1993 GNU Emacs Lisp Reference Manual Further Revised (v2.02), August 1993 Lucid Emacs Lisp Reference Manual (for 19.10) First Edition, March 1994 XEmacs Lisp Programmer's Manual (for 19.12) Second Edition, April 1995 GNU Emacs Lisp Reference Manual v2.4, June 1995 XEmacs Lisp Programmer's Manual (for 19.13) Third Edition, July 1995 XEmacs Lisp Reference Manual (for 19.14 and 20.0) v3.1, March 1996 XEmacs Lisp Reference Manual (for 19.15 and 20.1, 20.2) v3.2, April, May 1997 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc. Copyright (C) 1994, 1995 Sun Microsystems, Inc. Copyright (C) 1995, 1996 Ben Wing. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is 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 section entitled "GNU General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English.  File: lispref.info, Node: Sorting, Next: Columns, Prev: Auto Filling, Up: Text Sorting Text ============ The sorting functions described in this section all rearrange text in a buffer. This is in contrast to the function `sort', which rearranges the order of the elements of a list (*note Rearrangement::.). The values returned by these functions are not meaningful. - Function: sort-subr REVERSE NEXTRECFUN ENDRECFUN &optional STARTKEYFUN ENDKEYFUN This function is the general text-sorting routine that divides a buffer into records and sorts them. Most of the commands in this section use this function. To understand how `sort-subr' works, consider the whole accessible portion of the buffer as being divided into disjoint pieces called "sort records". The records may or may not be contiguous; they may not overlap. A portion of each sort record (perhaps all of it) is designated as the sort key. Sorting rearranges the records in order by their sort keys. Usually, the records are rearranged in order of ascending sort key. If the first argument to the `sort-subr' function, REVERSE, is non-`nil', the sort records are rearranged in order of descending sort key. The next four arguments to `sort-subr' are functions that are called to move point across a sort record. They are called many times from within `sort-subr'. 1. NEXTRECFUN is called with point at the end of a record. This function moves point to the start of the next record. The first record is assumed to start at the position of point when `sort-subr' is called. Therefore, you should usually move point to the beginning of the buffer before calling `sort-subr'. This function can indicate there are no more sort records by leaving point at the end of the buffer. 2. ENDRECFUN is called with point within a record. It moves point to the end of the record. 3. STARTKEYFUN is called to move point from the start of a record to the start of the sort key. This argument is optional; if it is omitted, the whole record is the sort key. If supplied, the function should either return a non-`nil' value to be used as the sort key, or return `nil' to indicate that the sort key is in the buffer starting at point. In the latter case, ENDKEYFUN is called to find the end of the sort key. 4. ENDKEYFUN is called to move point from the start of the sort key to the end of the sort key. This argument is optional. If STARTKEYFUN returns `nil' and this argument is omitted (or `nil'), then the sort key extends to the end of the record. There is no need for ENDKEYFUN if STARTKEYFUN returns a non-`nil' value. As an example of `sort-subr', here is the complete function definition for `sort-lines': ;; Note that the first two lines of doc string ;; are effectively one line when viewed by a user. (defun sort-lines (reverse beg end) "Sort lines in region alphabetically. Called from a program, there are three arguments: REVERSE (non-nil means reverse order), and BEG and END (the region to sort)." (interactive "P\nr") (save-restriction (narrow-to-region beg end) (goto-char (point-min)) (sort-subr reverse 'forward-line 'end-of-line))) Here `forward-line' moves point to the start of the next record, and `end-of-line' moves point to the end of record. We do not pass the arguments STARTKEYFUN and ENDKEYFUN, because the entire record is used as the sort key. The `sort-paragraphs' function is very much the same, except that its `sort-subr' call looks like this: (sort-subr reverse (function (lambda () (skip-chars-forward "\n \t\f"))) 'forward-paragraph) - Command: sort-regexp-fields REVERSE RECORD-REGEXP KEY-REGEXP START END This command sorts the region between START and END alphabetically as specified by RECORD-REGEXP and KEY-REGEXP. If REVERSE is a negative integer, then sorting is in reverse order. Alphabetical sorting means that two sort keys are compared by comparing the first characters of each, the second characters of each, and so on. If a mismatch is found, it means that the sort keys are unequal; the sort key whose character is less at the point of first mismatch is the lesser sort key. The individual characters are compared according to their numerical values. Since Emacs uses the ASCII character set, the ordering in that set determines alphabetical order. The value of the RECORD-REGEXP argument specifies how to divide the buffer into sort records. At the end of each record, a search is done for this regular expression, and the text that matches it is the next record. For example, the regular expression `^.+$', which matches lines with at least one character besides a newline, would make each such line into a sort record. *Note Regular Expressions::, for a description of the syntax and meaning of regular expressions. The value of the KEY-REGEXP argument specifies what part of each record is the sort key. The KEY-REGEXP could match the whole record, or only a part. In the latter case, the rest of the record has no effect on the sorted order of records, but it is carried along when the record moves to its new position. The KEY-REGEXP argument can refer to the text matched by a subexpression of RECORD-REGEXP, or it can be a regular expression on its own. If KEY-REGEXP is: `\DIGIT' then the text matched by the DIGITth `\(...\)' parenthesis grouping in RECORD-REGEXP is the sort key. `\&' then the whole record is the sort key. a regular expression then `sort-regexp-fields' searches for a match for the regular expression within the record. If such a match is found, it is the sort key. If there is no match for KEY-REGEXP within a record then that record is ignored, which means its position in the buffer is not changed. (The other records may move around it.) For example, if you plan to sort all the lines in the region by the first word on each line starting with the letter `f', you should set RECORD-REGEXP to `^.*$' and set KEY-REGEXP to `\'. The resulting expression looks like this: (sort-regexp-fields nil "^.*$" "\\" (region-beginning) (region-end)) If you call `sort-regexp-fields' interactively, it prompts for RECORD-REGEXP and KEY-REGEXP in the minibuffer. - Command: sort-lines REVERSE START END This command alphabetically sorts lines in the region between START and END. If REVERSE is non-`nil', the sort is in reverse order. - Command: sort-paragraphs REVERSE START END This command alphabetically sorts paragraphs in the region between START and END. If REVERSE is non-`nil', the sort is in reverse order. - Command: sort-pages REVERSE START END This command alphabetically sorts pages in the region between START and END. If REVERSE is non-`nil', the sort is in reverse order. - Command: sort-fields FIELD START END This command sorts lines in the region between START and END, comparing them alphabetically by the FIELDth field of each line. Fields are separated by whitespace and numbered starting from 1. If FIELD is negative, sorting is by the -FIELDth field from the end of the line. This command is useful for sorting tables. - Command: sort-numeric-fields FIELD START END This command sorts lines in the region between START and END, comparing them numerically by the FIELDth field of each line. The specified field must contain a number in each line of the region. Fields are separated by whitespace and numbered starting from 1. If FIELD is negative, sorting is by the -FIELDth field from the end of the line. This command is useful for sorting tables. - Command: sort-columns REVERSE &optional BEG END This command sorts the lines in the region between BEG and END, comparing them alphabetically by a certain range of columns. The column positions of BEG and END bound the range of columns to sort on. If REVERSE is non-`nil', the sort is in reverse order. One unusual thing about this command is that the entire line containing position BEG, and the entire line containing position END, are included in the region sorted. Note that `sort-columns' uses the `sort' utility program, and so cannot work properly on text containing tab characters. Use `M-x `untabify'' to convert tabs to spaces before sorting.  File: lispref.info, Node: Columns, Next: Indentation, Prev: Sorting, Up: Text Counting Columns ================ The column functions convert between a character position (counting characters from the beginning of the buffer) and a column position (counting screen characters from the beginning of a line). A character counts according to the number of columns it occupies on the screen. This means control characters count as occupying 2 or 4 columns, depending upon the value of `ctl-arrow', and tabs count as occupying a number of columns that depends on the value of `tab-width' and on the column where the tab begins. *Note Usual Display::. Column number computations ignore the width of the window and the amount of horizontal scrolling. Consequently, a column value can be arbitrarily high. The first (or leftmost) column is numbered 0. - Function: current-column This function returns the horizontal position of point, measured in columns, counting from 0 at the left margin. The column position is the sum of the widths of all the displayed representations of the characters between the start of the current line and point. For an example of using `current-column', see the description of `count-lines' in *Note Text Lines::. - Function: move-to-column COLUMN &optional FORCE This function moves point to COLUMN in the current line. The calculation of COLUMN takes into account the widths of the displayed representations of the characters between the start of the line and point. If column COLUMN is beyond the end of the line, point moves to the end of the line. If COLUMN is negative, point moves to the beginning of the line. If it is impossible to move to column COLUMN because that is in the middle of a multicolumn character such as a tab, point moves to the end of that character. However, if FORCE is non-`nil', and COLUMN is in the middle of a tab, then `move-to-column' converts the tab into spaces so that it can move precisely to column COLUMN. Other multicolumn characters can cause anomalies despite FORCE, since there is no way to split them. The argument FORCE also has an effect if the line isn't long enough to reach column COLUMN; in that case, it says to add whitespace at the end of the line to reach that column. If COLUMN is not an integer, an error is signaled. The return value is the column number actually moved to.  File: lispref.info, Node: Indentation, Next: Case Changes, Prev: Columns, Up: Text Indentation =========== The indentation functions are used to examine, move to, and change whitespace that is at the beginning of a line. Some of the functions can also change whitespace elsewhere on a line. Columns and indentation count from zero at the left margin. * Menu: * Primitive Indent:: Functions used to count and insert indentation. * Mode-Specific Indent:: Customize indentation for different modes. * Region Indent:: Indent all the lines in a region. * Relative Indent:: Indent the current line based on previous lines. * Indent Tabs:: Adjustable, typewriter-like tab stops. * Motion by Indent:: Move to first non-blank character.  File: lispref.info, Node: Primitive Indent, Next: Mode-Specific Indent, Up: Indentation Indentation Primitives ---------------------- This section describes the primitive functions used to count and insert indentation. The functions in the following sections use these primitives. - Function: current-indentation This function returns the indentation of the current line, which is the horizontal position of the first nonblank character. If the contents are entirely blank, then this is the horizontal position of the end of the line. - Command: indent-to COLUMN &optional MINIMUM This function indents from point with tabs and spaces until COLUMN is reached. If MINIMUM is specified and non-`nil', then at least that many spaces are inserted even if this requires going beyond COLUMN. Otherwise the function does nothing if point is already beyond COLUMN. The value is the column at which the inserted indentation ends. - User Option: indent-tabs-mode If this variable is non-`nil', indentation functions can insert tabs as well as spaces. Otherwise, they insert only spaces. Setting this variable automatically makes it local to the current buffer.  File: lispref.info, Node: Mode-Specific Indent, Next: Region Indent, Prev: Primitive Indent, Up: Indentation Indentation Controlled by Major Mode ------------------------------------ An important function of each major mode is to customize the key to indent properly for the language being edited. This section describes the mechanism of the key and how to control it. The functions in this section return unpredictable values. - Variable: indent-line-function This variable's value is the function to be used by (and various commands) to indent the current line. The command `indent-according-to-mode' does no more than call this function. In Lisp mode, the value is the symbol `lisp-indent-line'; in C mode, `c-indent-line'; in Fortran mode, `fortran-indent-line'. In Fundamental mode, Text mode, and many other modes with no standard for indentation, the value is `indent-to-left-margin' (which is the default value). - Command: indent-according-to-mode This command calls the function in `indent-line-function' to indent the current line in a way appropriate for the current major mode. - Command: indent-for-tab-command This command calls the function in `indent-line-function' to indent the current line; except that if that function is `indent-to-left-margin', it calls `insert-tab' instead. (That is a trivial command that inserts a tab character.) - Command: newline-and-indent This function inserts a newline, then indents the new line (the one following the newline just inserted) according to the major mode. It does indentation by calling the current `indent-line-function'. In programming language modes, this is the same thing does, but in some text modes, where inserts a tab, `newline-and-indent' indents to the column specified by `left-margin'. - Command: reindent-then-newline-and-indent This command reindents the current line, inserts a newline at point, and then reindents the new line (the one following the newline just inserted). This command does indentation on both lines according to the current major mode, by calling the current value of `indent-line-function'. In programming language modes, this is the same thing does, but in some text modes, where inserts a tab, `reindent-then-newline-and-indent' indents to the column specified by `left-margin'.  File: lispref.info, Node: Region Indent, Next: Relative Indent, Prev: Mode-Specific Indent, Up: Indentation Indenting an Entire Region -------------------------- This section describes commands that indent all the lines in the region. They return unpredictable values. - Command: indent-region START END TO-COLUMN This command indents each nonblank line starting between START (inclusive) and END (exclusive). If TO-COLUMN is `nil', `indent-region' indents each nonblank line by calling the current mode's indentation function, the value of `indent-line-function'. If TO-COLUMN is non-`nil', it should be an integer specifying the number of columns of indentation; then this function gives each line exactly that much indentation, by either adding or deleting whitespace. If there is a fill prefix, `indent-region' indents each line by making it start with the fill prefix. - Variable: indent-region-function The value of this variable is a function that can be used by `indent-region' as a short cut. You should design the function so that it will produce the same results as indenting the lines of the region one by one, but presumably faster. If the value is `nil', there is no short cut, and `indent-region' actually works line by line. A short-cut function is useful in modes such as C mode and Lisp mode, where the `indent-line-function' must scan from the beginning of the function definition: applying it to each line would be quadratic in time. The short cut can update the scan information as it moves through the lines indenting them; this takes linear time. In a mode where indenting a line individually is fast, there is no need for a short cut. `indent-region' with a non-`nil' argument TO-COLUMN has a different meaning and does not use this variable. - Command: indent-rigidly START END COUNT This command indents all lines starting between START (inclusive) and END (exclusive) sideways by COUNT columns. This "preserves the shape" of the affected region, moving it as a rigid unit. Consequently, this command is useful not only for indenting regions of unindented text, but also for indenting regions of formatted code. For example, if COUNT is 3, this command adds 3 columns of indentation to each of the lines beginning in the region specified. In Mail mode, `C-c C-y' (`mail-yank-original') uses `indent-rigidly' to indent the text copied from the message being replied to. - Function: indent-code-rigidly START END COLUMNS &optional NOCHANGE-REGEXP This is like `indent-rigidly', except that it doesn't alter lines that start within strings or comments. In addition, it doesn't alter a line if NOCHANGE-REGEXP matches at the beginning of the line (if NOCHANGE-REGEXP is non-`nil').  File: lispref.info, Node: Relative Indent, Next: Indent Tabs, Prev: Region Indent, Up: Indentation Indentation Relative to Previous Lines -------------------------------------- This section describes two commands that indent the current line based on the contents of previous lines. - Command: indent-relative &optional UNINDENTED-OK This command inserts whitespace at point, extending to the same column as the next "indent point" of the previous nonblank line. An indent point is a non-whitespace character following whitespace. The next indent point is the first one at a column greater than the current column of point. For example, if point is underneath and to the left of the first non-blank character of a line of text, it moves to that column by inserting whitespace. If the previous nonblank line has no next indent point (i.e., none at a great enough column position), `indent-relative' either does nothing (if UNINDENTED-OK is non-`nil') or calls `tab-to-tab-stop'. Thus, if point is underneath and to the right of the last column of a short line of text, this command ordinarily moves point to the next tab stop by inserting whitespace. The return value of `indent-relative' is unpredictable. In the following example, point is at the beginning of the second line: This line is indented twelve spaces. -!-The quick brown fox jumped. Evaluation of the expression `(indent-relative nil)' produces the following: This line is indented twelve spaces. -!-The quick brown fox jumped. In this example, point is between the `m' and `p' of `jumped': This line is indented twelve spaces. The quick brown fox jum-!-ped. Evaluation of the expression `(indent-relative nil)' produces the following: This line is indented twelve spaces. The quick brown fox jum -!-ped. - Command: indent-relative-maybe This command indents the current line like the previous nonblank line. It calls `indent-relative' with `t' as the UNINDENTED-OK argument. The return value is unpredictable. If the previous nonblank line has no indent points beyond the current column, this command does nothing.  File: lispref.info, Node: Indent Tabs, Next: Motion by Indent, Prev: Relative Indent, Up: Indentation Adjustable "Tab Stops" ---------------------- This section explains the mechanism for user-specified "tab stops" and the mechanisms that use and set them. The name "tab stops" is used because the feature is similar to that of the tab stops on a typewriter. The feature works by inserting an appropriate number of spaces and tab characters to reach the next tab stop column; it does not affect the display of tab characters in the buffer (*note Usual Display::.). Note that the character as input uses this tab stop feature only in a few major modes, such as Text mode. - Command: tab-to-tab-stop This command inserts spaces or tabs up to the next tab stop column defined by `tab-stop-list'. It searches the list for an element greater than the current column number, and uses that element as the column to indent to. It does nothing if no such element is found. - User Option: tab-stop-list This variable is the list of tab stop columns used by `tab-to-tab-stops'. The elements should be integers in increasing order. The tab stop columns need not be evenly spaced. Use `M-x edit-tab-stops' to edit the location of tab stops interactively.  File: lispref.info, Node: Motion by Indent, Prev: Indent Tabs, Up: Indentation Indentation-Based Motion Commands --------------------------------- These commands, primarily for interactive use, act based on the indentation in the text. - Command: back-to-indentation This command moves point to the first non-whitespace character in the current line (which is the line in which point is located). It returns `nil'. - Command: backward-to-indentation ARG This command moves point backward ARG lines and then to the first nonblank character on that line. It returns `nil'. - Command: forward-to-indentation ARG This command moves point forward ARG lines and then to the first nonblank character on that line. It returns `nil'.  File: lispref.info, Node: Case Changes, Next: Text Properties, Prev: Indentation, Up: Text Case Changes ============ The case change commands described here work on text in the current buffer. *Note Character Case::, for case conversion commands that work on strings and characters. *Note Case Tables::, for how to customize which characters are upper or lower case and how to convert them. - Command: capitalize-region START END This function capitalizes all words in the region defined by START and END. To capitalize means to convert each word's first character to upper case and convert the rest of each word to lower case. The function returns `nil'. If one end of the region is in the middle of a word, the part of the word within the region is treated as an entire word. When `capitalize-region' is called interactively, START and END are point and the mark, with the smallest first. ---------- Buffer: foo ---------- This is the contents of the 5th foo. ---------- Buffer: foo ---------- (capitalize-region 1 44) => nil ---------- Buffer: foo ---------- This Is The Contents Of The 5th Foo. ---------- Buffer: foo ---------- - Command: downcase-region START END This function converts all of the letters in the region defined by START and END to lower case. The function returns `nil'. When `downcase-region' is called interactively, START and END are point and the mark, with the smallest first. - Command: upcase-region START END This function converts all of the letters in the region defined by START and END to upper case. The function returns `nil'. When `upcase-region' is called interactively, START and END are point and the mark, with the smallest first. - Command: capitalize-word COUNT This function capitalizes COUNT words after point, moving point over as it does. To capitalize means to convert each word's first character to upper case and convert the rest of each word to lower case. If COUNT is negative, the function capitalizes the -COUNT previous words but does not move point. The value is `nil'. If point is in the middle of a word, the part of the word before point is ignored when moving forward. The rest is treated as an entire word. When `capitalize-word' is called interactively, COUNT is set to the numeric prefix argument. - Command: downcase-word COUNT This function converts the COUNT words after point to all lower case, moving point over as it does. If COUNT is negative, it converts the -COUNT previous words but does not move point. The value is `nil'. When `downcase-word' is called interactively, COUNT is set to the numeric prefix argument. - Command: upcase-word COUNT This function converts the COUNT words after point to all upper case, moving point over as it does. If COUNT is negative, it converts the -COUNT previous words but does not move point. The value is `nil'. When `upcase-word' is called interactively, COUNT is set to the numeric prefix argument.  File: lispref.info, Node: Text Properties, Next: Substitution, Prev: Case Changes, Up: Text Text Properties =============== Text properties are an alternative interface to extents (*note Extents::.), and are built on top of them. They are useful when you want to view textual properties as being attached to the characters themselves rather than to intervals of characters. The text property interface is compatible with FSF Emacs. Each character position in a buffer or a string can have a "text property list", much like the property list of a symbol (*note Property Lists::.). The properties belong to a particular character at a particular place, such as, the letter `T' at the beginning of this sentence or the first `o' in `foo'--if the same character occurs in two different places, the two occurrences generally have different properties. Each property has a name and a value. Both of these can be any Lisp object, but the name is normally a symbol. The usual way to access the property list is to specify a name and ask what value corresponds to it. Note that FSF Emacs also looks at the `category' property to find defaults for text properties. We consider this too bogus to implement. Copying text between strings and buffers preserves the properties along with the characters; this includes such diverse functions as `substring', `insert', and `buffer-substring'. * Menu: * Examining Properties:: Looking at the properties of one character. * Changing Properties:: Setting the properties of a range of text. * Property Search:: Searching for where a property changes value. * Special Properties:: Particular properties with special meanings. * Saving Properties:: Saving text properties in files, and reading them back.  File: lispref.info, Node: Examining Properties, Next: Changing Properties, Up: Text Properties Examining Text Properties ------------------------- The simplest way to examine text properties is to ask for the value of a particular property of a particular character. For that, use `get-text-property'. Use `text-properties-at' to get the entire property list of a character. *Note Property Search::, for functions to examine the properties of a number of characters at once. These functions handle both strings and buffers. (Keep in mind that positions in a string start from 0, whereas positions in a buffer start from 1.) - Function: get-text-property POS PROP &optional OBJECT This function returns the value of the PROP property of the character after position POS in OBJECT (a buffer or string). The argument OBJECT is optional and defaults to the current buffer. - Function: get-char-property POS PROP &optional OBJECT This function is like `get-text-property', except that it checks all extents, not just text-property extents. - Function: text-properties-at POSITION &optional OBJECT This function returns the entire property list of the character at POSITION in the string or buffer OBJECT. If OBJECT is `nil', it defaults to the current buffer. - Variable: default-text-properties This variable holds a property list giving default values for text properties. Whenever a character does not specify a value for a property, the value stored in this list is used instead. Here is an example: (setq default-text-properties '(foo 69)) ;; Make sure character 1 has no properties of its own. (set-text-properties 1 2 nil) ;; What we get, when we ask, is the default value. (get-text-property 1 'foo) => 69  File: lispref.info, Node: Changing Properties, Next: Property Search, Prev: Examining Properties, Up: Text Properties Changing Text Properties ------------------------ The primitives for changing properties apply to a specified range of text. The function `set-text-properties' (see end of section) sets the entire property list of the text in that range; more often, it is useful to add, change, or delete just certain properties specified by name. Since text properties are considered part of the buffer's contents, and can affect how the buffer looks on the screen, any change in the text properties is considered a buffer modification. Buffer text property changes are undoable (*note Undo::.). - Function: put-text-property START END PROP VALUE &optional OBJECT This function sets the PROP property to VALUE for the text between START and END in the string or buffer OBJECT. If OBJECT is `nil', it defaults to the current buffer. - Function: add-text-properties START END PROPS &optional OBJECT This function modifies the text properties for the text between START and END in the string or buffer OBJECT. If OBJECT is `nil', it defaults to the current buffer. The argument PROPS specifies which properties to change. It should have the form of a property list (*note Property Lists::.): a list whose elements include the property names followed alternately by the corresponding values. The return value is `t' if the function actually changed some property's value; `nil' otherwise (if PROPS is `nil' or its values agree with those in the text). For example, here is how to set the `comment' and `face' properties of a range of text: (add-text-properties START END '(comment t face highlight)) - Function: remove-text-properties START END PROPS &optional OBJECT This function deletes specified text properties from the text between START and END in the string or buffer OBJECT. If OBJECT is `nil', it defaults to the current buffer. The argument PROPS specifies which properties to delete. It should have the form of a property list (*note Property Lists::.): a list whose elements are property names alternating with corresponding values. But only the names matter--the values that accompany them are ignored. For example, here's how to remove the `face' property. (remove-text-properties START END '(face nil)) The return value is `t' if the function actually changed some property's value; `nil' otherwise (if PROPS is `nil' or if no character in the specified text had any of those properties). - Function: set-text-properties START END PROPS &optional OBJECT This function completely replaces the text property list for the text between START and END in the string or buffer OBJECT. If OBJECT is `nil', it defaults to the current buffer. The argument PROPS is the new property list. It should be a list whose elements are property names alternating with corresponding values. After `set-text-properties' returns, all the characters in the specified range have identical properties. If PROPS is `nil', the effect is to get rid of all properties from the specified range of text. Here's an example: (set-text-properties START END nil) See also the function `buffer-substring-without-properties' (*note Buffer Contents::.) which copies text from the buffer but does not copy its properties.  File: lispref.info, Node: Property Search, Next: Special Properties, Prev: Changing Properties, Up: Text Properties Property Search Functions ------------------------- In typical use of text properties, most of the time several or many consecutive characters have the same value for a property. Rather than writing your programs to examine characters one by one, it is much faster to process chunks of text that have the same property value. Here are functions you can use to do this. They use `eq' for comparing property values. In all cases, OBJECT defaults to the current buffer. For high performance, it's very important to use the LIMIT argument to these functions, especially the ones that search for a single property--otherwise, they may spend a long time scanning to the end of the buffer, if the property you are interested in does not change. Remember that a position is always between two characters; the position returned by these functions is between two characters with different properties. - Function: next-property-change POS &optional OBJECT LIMIT The function scans the text forward from position POS in the string or buffer OBJECT till it finds a change in some text property, then returns the position of the change. In other words, it returns the position of the first character beyond POS whose properties are not identical to those of the character just after POS. If LIMIT is non-`nil', then the scan ends at position LIMIT. If there is no property change before that point, `next-property-change' returns LIMIT. The value is `nil' if the properties remain unchanged all the way to the end of OBJECT and LIMIT is `nil'. If the value is non-`nil', it is a position greater than or equal to POS. The value equals POS only when LIMIT equals POS. Here is an example of how to scan the buffer by chunks of text within which all properties are constant: (while (not (eobp)) (let ((plist (text-properties-at (point))) (next-change (or (next-property-change (point) (current-buffer)) (point-max)))) Process text from point to NEXT-CHANGE... (goto-char next-change))) - Function: next-single-property-change POS PROP &optional OBJECT LIMIT The function scans the text forward from position POS in the string or buffer OBJECT till it finds a change in the PROP property, then returns the position of the change. In other words, it returns the position of the first character beyond POS whose PROP property differs from that of the character just after POS. If LIMIT is non-`nil', then the scan ends at position LIMIT. If there is no property change before that point, `next-single-property-change' returns LIMIT. The value is `nil' if the property remains unchanged all the way to the end of OBJECT and LIMIT is `nil'. If the value is non-`nil', it is a position greater than or equal to POS; it equals POS only if LIMIT equals POS. - Function: previous-property-change POS &optional OBJECT LIMIT This is like `next-property-change', but scans back from POS instead of forward. If the value is non-`nil', it is a position less than or equal to POS; it equals POS only if LIMIT equals POS. - Function: previous-single-property-change POS PROP &optional OBJECT LIMIT This is like `next-single-property-change', but scans back from POS instead of forward. If the value is non-`nil', it is a position less than or equal to POS; it equals POS only if LIMIT equals POS. - Function: text-property-any START END PROP VALUE &optional OBJECT This function returns non-`nil' if at least one character between START and END has a property PROP whose value is VALUE. More precisely, it returns the position of the first such character. Otherwise, it returns `nil'. The optional fifth argument, OBJECT, specifies the string or buffer to scan. Positions are relative to OBJECT. The default for OBJECT is the current buffer. - Function: text-property-not-all START END PROP VALUE &optional OBJECT This function returns non-`nil' if at least one character between START and END has a property PROP whose value differs from VALUE. More precisely, it returns the position of the first such character. Otherwise, it returns `nil'. The optional fifth argument, OBJECT, specifies the string or buffer to scan. Positions are relative to OBJECT. The default for OBJECT is the current buffer.  File: lispref.info, Node: Special Properties, Next: Saving Properties, Prev: Property Search, Up: Text Properties Properties with Special Meanings -------------------------------- The predefined properties are the same as those for extents. *Note Extent Properties::.  File: lispref.info, Node: Saving Properties, Prev: Special Properties, Up: Text Properties Saving Text Properties in Files ------------------------------- You can save text properties in files, and restore text properties when inserting the files, using these two hooks: - Variable: write-region-annotate-functions This variable's value is a list of functions for `write-region' to run to encode text properties in some fashion as annotations to the text being written in the file. *Note Writing to Files::. Each function in the list is called with two arguments: the start and end of the region to be written. These functions should not alter the contents of the buffer. Instead, they should return lists indicating annotations to write in the file in addition to the text in the buffer. Each function should return a list of elements of the form `(POSITION . STRING)', where POSITION is an integer specifying the relative position in the text to be written, and STRING is the annotation to add there. Each list returned by one of these functions must be already sorted in increasing order by POSITION. If there is more than one function, `write-region' merges the lists destructively into one sorted list. When `write-region' actually writes the text from the buffer to the file, it intermixes the specified annotations at the corresponding positions. All this takes place without modifying the buffer. - Variable: after-insert-file-functions This variable holds a list of functions for `insert-file-contents' to call after inserting a file's contents. These functions should scan the inserted text for annotations, and convert them to the text properties they stand for. Each function receives one argument, the length of the inserted text; point indicates the start of that text. The function should scan that text for annotations, delete them, and create the text properties that the annotations specify. The function should return the updated length of the inserted text, as it stands after those changes. The value returned by one function becomes the argument to the next function. These functions should always return with point at the beginning of the inserted text. The intended use of `after-insert-file-functions' is for converting some sort of textual annotations into actual text properties. But other uses may be possible. We invite users to write Lisp programs to store and retrieve text properties in files, using these hooks, and thus to experiment with various data formats and find good ones. Eventually we hope users will produce good, general extensions we can install in Emacs. We suggest not trying to handle arbitrary Lisp objects as property names or property values--because a program that general is probably difficult to write, and slow. Instead, choose a set of possible data types that are reasonably flexible, and not too hard to encode. *Note Format Conversion::, for a related feature.  File: lispref.info, Node: Substitution, Next: Registers, Prev: Text Properties, Up: Text Substituting for a Character Code ================================= The following functions replace characters within a specified region based on their character codes. - Function: subst-char-in-region START END OLD-CHAR NEW-CHAR &optional NOUNDO This function replaces all occurrences of the character OLD-CHAR with the character NEW-CHAR in the region of the current buffer defined by START and END. If NOUNDO is non-`nil', then `subst-char-in-region' does not record the change for undo and does not mark the buffer as modified. This feature is used for controlling selective display (*note Selective Display::.). `subst-char-in-region' does not move point and returns `nil'. ---------- Buffer: foo ---------- This is the contents of the buffer before. ---------- Buffer: foo ---------- (subst-char-in-region 1 20 ?i ?X) => nil ---------- Buffer: foo ---------- ThXs Xs the contents of the buffer before. ---------- Buffer: foo ---------- - Function: translate-region START END TABLE This function applies a translation table to the characters in the buffer between positions START and END. The translation table TABLE is a string; `(aref TABLE OCHAR)' gives the translated character corresponding to OCHAR. If the length of TABLE is less than 256, any characters with codes larger than the length of TABLE are not altered by the translation. The return value of `translate-region' is the number of characters that were actually changed by the translation. This does not count characters that were mapped into themselves in the translation table.  File: lispref.info, Node: Registers, Next: Transposition, Prev: Substitution, Up: Text Registers ========= A register is a sort of variable used in XEmacs editing that can hold a marker, a string, a rectangle, a window configuration (of one frame), or a frame configuration (of all frames). Each register is named by a single character. All characters, including control and meta characters (but with the exception of `C-g'), can be used to name registers. Thus, there are 255 possible registers. A register is designated in Emacs Lisp by a character that is its name. The functions in this section return unpredictable values unless otherwise stated. - Variable: register-alist This variable is an alist of elements of the form `(NAME . CONTENTS)'. Normally, there is one element for each XEmacs register that has been used. The object NAME is a character (an integer) identifying the register. The object CONTENTS is a string, marker, or list representing the register contents. A string represents text stored in the register. A marker represents a position. A list represents a rectangle; its elements are strings, one per line of the rectangle. - Function: get-register REG This function returns the contents of the register REG, or `nil' if it has no contents. - Function: set-register REG VALUE This function sets the contents of register REG to VALUE. A register can be set to any value, but the other register functions expect only certain data types. The return value is VALUE. - Command: view-register REG This command displays what is contained in register REG. - Command: insert-register REG &optional BEFOREP This command inserts contents of register REG into the current buffer. Normally, this command puts point before the inserted text, and the mark after it. However, if the optional second argument BEFOREP is non-`nil', it puts the mark before and point after. You can pass a non-`nil' second argument BEFOREP to this function interactively by supplying any prefix argument. If the register contains a rectangle, then the rectangle is inserted with its upper left corner at point. This means that text is inserted in the current line and underneath it on successive lines. If the register contains something other than saved text (a string) or a rectangle (a list), currently useless things happen. This may be changed in the future.  File: lispref.info, Node: Transposition, Next: Change Hooks, Prev: Registers, Up: Text Transposition of Text ===================== This subroutine is used by the transposition commands. - Function: transpose-regions START1 END1 START2 END2 &optional LEAVE-MARKERS This function exchanges two nonoverlapping portions of the buffer. Arguments START1 and END1 specify the bounds of one portion and arguments START2 and END2 specify the bounds of the other portion. Normally, `transpose-regions' relocates markers with the transposed text; a marker previously positioned within one of the two transposed portions moves along with that portion, thus remaining between the same two characters in their new position. However, if LEAVE-MARKERS is non-`nil', `transpose-regions' does not do this--it leaves all markers unrelocated.  File: lispref.info, Node: Change Hooks, Prev: Transposition, Up: Text Change Hooks ============ These hook variables let you arrange to take notice of all changes in all buffers (or in a particular buffer, if you make them buffer-local). The functions you use in these hooks should save and restore the match data if they do anything that uses regular expressions; otherwise, they will interfere in bizarre ways with the editing operations that call them. Buffer changes made while executing the following hooks don't themselves cause any change hooks to be invoked. - Variable: before-change-functions This variable holds a list of a functions to call before any buffer modification. Each function gets two arguments, the beginning and end of the region that is about to change, represented as integers. The buffer that is about to change is always the current buffer. - Variable: after-change-functions This variable holds a list of a functions to call after any buffer modification. Each function receives three arguments: the beginning and end of the region just changed, and the length of the text that existed before the change. (To get the current length, subtract the region beginning from the region end.) All three arguments are integers. The buffer that's about to change is always the current buffer. - Variable: before-change-function This obsolete variable holds one function to call before any buffer modification (or `nil' for no function). It is called just like the functions in `before-change-functions'. - Variable: after-change-function This obsolete variable holds one function to call after any buffer modification (or `nil' for no function). It is called just like the functions in `after-change-functions'. - Variable: first-change-hook This variable is a normal hook that is run whenever a buffer is changed that was previously in the unmodified state.