# Extending &kate;

## Introduction

Like any advanced text editor, &kate; offers a variety of ways to extend its functionality. You can write simple scripts to add functionality with JavaScript, add enhanced functionality to the editor component with Editor Component Plugins, or add even more functionality to the editor itself with &kate; Application Plugins written in C++ or &pate; Plugins written in Python. Finally, once you have extended &kate;, you are welcome to join us and share your enhancements with the world!

## Scripting with JavaScript

Since &kappname; 3.4 in &kde; 4.4 the &kappname; editor component is easily extensible by writing scripts. The scripting language is ECMAScript (widely known as JavaScript). &kappname; supports two kinds of scripts: indentation and command line scripts.

### Indentation Scripts

Indentation scripts - also referred as indenters - automatically indent the source code while typing text. As an example, after hitting the return key the indentation level often increases.

The following sections describe step by step how to create the skeleton for a simple indenter. As a first step, create a new `*.js` file called ⪚ `javascript.js` in the local home folder `$KDEHOME/share/apps/katepart/script/indentation`.

#### The Indentation Script Header

The header of the file `javascript.js` is embedded in a comment and is of the following form:

    /* kate-script
     * name: JavaScript
     * author: Example Name <example.name@some.address.org>
     * license: BSD
     * revision: 1
     * kate-version: 3.4
     * required-syntax-style: javascript
     * indent-languages: javascript
     * priority: 0
     * i18n-catalog: mycatalog
     *
     * A line without a colon ':' stops header parsing. That is, you can add optional
     * text here such as a detailed license.
     */

Each entry is explained in detail now:

- `kate-script` [required]: This text string has to appear in the first line of the `*.js` file, otherwise &kappname; skips the script.

- `name` [required]: This is the indenter name that appears in the menu Tools Indentation and in the configuration dialog.

- `author` [optional]: The author's name and contact information.

- `license` [optional]: Short form of the license, such as BSD or LGPLv3.

- `revision` [required]: The revision of the script. This number should be increased whenever the script is modified.

- `kate-version` [required]: Minimum required &kappname; version.

- `required-syntax-style` [optional]: Comma separated list of required syntax highlighting styles. This is important for indenters that rely on specific highlight information in the document. If a required syntax style is specified, the indenter is available only when the appropriate highlighter is active. This prevents undefined behavior caused by using the indenter without the expected highlighting schema. For instance, the Ruby indenter makes use of this in the files `ruby.js` and `ruby.xml`.

- `indent-languages` [optional]: Comma separated list of syntax styles the indenter can indent correctly, ⪚: c++, java.

- `priority` [optional]: If several indenters are suited for a certain highlighted file, the priority decides which indenter is chosen as default indenter.

- `i18n-catalog` [optional]: Additional message catalog (`po` file) loaded for translation of 3rd-party indenters.

&kappname; reads all pairs of the form `key`:`value` until it cannot find a colon anymore. This implies that the header can contain arbitrary text such as a license as shown in the example.

#### The Indenter Source Code

Having specified the header this section explains how the indentation scripting itself works. The basic skeleton of the body looks like this:

    // required katepart js libraries, e.g. range.js if you use Range
    require ("range.js");

    triggerCharacters = "{}/:;";
    function indent(line, indentWidth, ch)
    {
        // called for each newline (ch == '\n') and all characters specified in
        // the global variable triggerCharacters. When calling ToolsAlign
        // the variable ch is empty, i.e. ch == ''.
        //
        // see also: Scripting API
        return -2;
    }

The function `indent()` has three parameters:

- `line`: the line that has to be indented

- `indentWidth`: the indentation width in number of spaces

- `ch`: either a newline character (`ch == '\n'`), the trigger character specified in `triggerCharacters` or empty if the user invoked the action Tools Align.

The return value of the `indent()` function specifies how the line will be indented. If the return value is a simple integer number, it is interpreted as follows:

- return value `-2`: do nothing

- return value `-1`: keep indentation (searches for previous non-blank line)

- return value `0`: numbers >= 0 specify the indentation depth in spaces

Alternatively, an array of two elements can be returned:

- `return [ indent, align ];`

In this case, the first element is the indentation depth as above with the same meaning of the special values. However, the second element is an absolute value representing a column for alignment. If this value is higher than the indent value, the difference represents a number of spaces to be added after the indentation of the first parameter. Otherwise, the second number is ignored. Using tabs and spaces for indentation is often referred to as mixed mode.

Consider the following example: Assume using tabs to indent, and tab width is set to 4. Here, <tab> represents a tab and '.' a space:

    1: <tab><tab>foobar("hello",
    2: <tab><tab>......."world");

When indenting line 2, the `indent()` function returns [8, 15]. As result, two tabs are inserted to indent to column 8, and 7 spaces are added to align the second parameter under the first, so that it stays aligned if the file is viewed with a different tab width.

A default &kde; installation ships &kappname; with several indenters. The corresponding JavaScript source code can be found in `$KDEDIR/share/apps/katepart/script/indentation`.

Developing an indenter requires reloading the scripts to see whether the changes behave appropriately. Instead of restarting the application, simply switch to the command line and invoke the command `reload-scripts`.

If you develop useful scripts please consider contributing to the &kappname; Project by contacting the mailing list.

### Command Line Scripts

As it is hard to satisfy everyone's needs, &kappname; supports little helper tools for quick text manipulation through the built-in command line. For instance, the command `sort` is implemented as a script. This section explains how to create `*.js` files to extend &kappname; with arbitrary helper scripts.

Command line scripts are located in the same folder as indentation scripts. So as a first step, create a new `*.js` file called `myutils.js` in the local home folder `$KDEHOME/share/apps/katepart/script/commands`.

#### The Command Line Script Header

The header of each command line script is embedded in a comment and is of the following form:

    /* kate-script
     * author: Example Name <example.name@some.address.org>
     * license: BSD
     * revision: 1
     * kate-version: 3.4
     * functions: sort, format-paragraph
     * i18n-catalog: mycatalog
     *
     * A line without a colon ':' stops header parsing. That is, you can add optional
     * text here such as a detailed license.
     */

Each entry is explained in detail now:

- `kate-script` [required]: This text string has to appear in the first line of the `*.js` file, otherwise &kappname; skips the script.

- `author` [optional]: The author's name and contact information.

- `license` [optional]: Short form of the license, such as BSD or LGPLv3.

- `revision` [required]: The revision of the script. This number should be increased whenever the script is modified.

- `kate-version` [required]: Minimum required &kappname; version.

- `functions` [required]: Comma separated list of commands in the script.

- `i18n-catalog` [optional]: Additional message catalog (`po` file) loaded for translation of 3rd-party scripts.

&kappname; reads all pairs of the form `key`:`value` until it cannot find a colon anymore. This implies that the header can contain arbitrary text such as a license as shown in the example. The value of the key functions is a comma separated list of command line commands. This means a single script contains an arbitrary number of command line commands. Each function is available through &kappname;'s built-in command line.

#### The Script Source Code

All functions specified in the header have to be implemented in the script. For instance, the script file from the example above needs to implement the two functions `sort` and `format-paragraph`. All functions have the following syntax:

    // required katepart js libraries, e.g. range.js if you use Range
    require ("range.js");

    function <name>(arg1, arg2, ...)
    {
        // ... implementation, see also: Scripting API
    }

Arguments in the command line are passed to the function as `arg1`, `arg2`, etc. In order to provide documentation for each command, simply implement the '`help`' function as follows:

    function help(cmd)
    {
        if (cmd == "sort") {
            return i18n("Sort the selected text.");
        } else if (cmd == "...") {
            // ...
        }
    }

Executing `help sort` in the command line then calls this help function with the argument `cmd` set to the given command, &ie; `cmd == "sort"`. &kappname; then presents the returned text as documentation to the user. Make sure to translate the strings.

##### Binding Shortcuts

In order to be able to assign shortcuts, the script needs to provide a function called `action` as follows:

    function action(cmd)
    {
        var a = new Object();
        if (cmd == "sort") {
            a.text = i18n("Sort Selected Text");
            a.icon = "";
            a.category = "";
            a.interactive = false;
            a.shortcut = "";
        } else if (cmd == "moveLinesDown") {
            // same for next action
        }
        return a;
    }

The parameter `cmd` of the function specifies the command for which a shortcut is requested. There are several fields you have to specify in the returned javascript object:

- `a.text` [required]: The text appears in the menu Tools Scripts. Make sure to use `i18n` for translation.

- `a.icon` [optional]: The icon appears next to the text in the menu. All &kde; icon names can be used here.

- `a.category` [optional]: If a category is specified, the script appears in a submenu. Make sure to use `i18n` for translation.

- `a.interactive` [optional]: If the script needs user input, set this to `true`.

- `a.shortcut` [optional]: The shortcut given here is the default shortcut. Example: Ctrl+Alt+t. See the Qt documentation for further details.

Developing a command line script requires reloading the scripts to see whether the changes behave appropriately. Instead of restarting the application, simply switch to the command line and invoke the command `reload-scripts`.

If you develop useful scripts please consider contributing to the &kappname; Project by contacting the mailing list.

### Scripting API

The scripting API presented here is available to all scripts, &ie; indentation scripts and command line commands. The `Cursor` and `Range` classes are provided by library files in `$KDEDIR/share/apps/katepart/libraries`. If you want to use them in your script, which needs to use some of the `Document` or `View` functions, please include the necessary library by using:

    // required katepart js libraries, e.g. range.js if you use Range
    require ("range.js");

To extend the standard scripting API with your own functions and prototypes simply create a new file in &kde;'s local configuration folder `$KDEHOME/share/apps/katepart/libraries` and include it into your script using:

    require ("myscriptnamehere.js");

To extend existing prototypes like `Cursor` or `Range`, the recommended way is to not modify the global `*.js` files. Instead, change the `Cursor` prototype in JavaScript after the `cursor.js` is included into your script via `require`.

#### Cursors and Ranges

As &kappname; is a text editor, all the scripting API is based on cursors and ranges whenever possible. A Cursor is a simple `(line, column)` tuple representing a text position in the document. A Range spans text from a starting cursor position to an ending cursor position. The API is explained in detail in the next sections.

##### The Cursor Prototype

    Cursor();

- Constructor. Returns a Cursor at position `(0, 0)`.

  Example: `var cursor = new Cursor();`

    Cursor(int line, int column);

- Constructor. Returns a Cursor at position (line, column).

  Example: `var cursor = new Cursor(3, 42);`

    Cursor(Cursor other);

- Copy constructor. Returns a copy of the cursor `other`.

  Example: `var copy = new Cursor(other);`

    Cursor Cursor.clone();

- Returns a clone of the cursor.

  Example: `var clone = cursor.clone();`

    Cursor.setPosition(int line, int column);

- Sets the cursor position to `line` and `column`.

  Since: &kde; 4.11

    bool Cursor.isValid();

- Check whether the cursor is valid. The cursor is invalid, if line and/or column are set to `-1`.

  Example: `var valid = cursor.isValid();`

    Cursor Cursor.invalid();

- Returns a new invalid cursor located at `(-1, -1)`.

  Example: `var invalidCursor = cursor.invalid();`

    int Cursor.compareTo(Cursor other);

- Compares this cursor to the cursor `other`. Returns

  - `-1`, if this cursor is located before the cursor `other`,

  - `0`, if both cursors equal and

  - `+1`, if this cursor is located after the cursor `other`.

    bool Cursor.equals(Cursor other);

- Returns `true`, if this cursor and the cursor `other` are equal, otherwise `false`.

    String Cursor.toString();

- Returns the cursor as a string of the form `Cursor(line, column)`.

##### The Range Prototype

    Range();

- Constructor. Calling `new Range()` returns a Range at (0, 0) - (0, 0).

    Range(Cursor start, Cursor end);

- Constructor. Calling `new Range(`start`, `end`)` returns the Range (`start`, `end`).

    Range(int startLine, int startColumn, int endLine, int endColumn);

- Constructor. Calling `new Range(`startLine`, `startColumn`, `endLine`, `endColumn`)` returns the Range from (`startLine`, `startColumn`) to (`endLine`, `endColumn`).

    Range(Range other);

- Copy constructor. Returns a copy of Range `other`.

    Range Range.clone();

- Returns a clone of the range.

  Example: `var clone = range.clone();`

    bool Range.isEmpty();

- Returns `true`, if the start and end cursors are equal.

  Example: `var empty = range.isEmpty();`

  Since: &kde; 4.11

    bool Range.isValid();

- Returns `true`, if both start and end cursor are valid, otherwise `false`.

  Example: `var valid = range.isValid();`

    Range Range.invalid();

- Returns the Range from (-1, -1) to (-1, -1).

    bool Range.contains(Cursor cursor);

- Returns `true`, if this range contains the cursor position, otherwise `false`.

    bool Range.contains(Range other);

- Returns `true`, if this range contains the Range `other`, otherwise `false`.

    bool Range.containsColumn(int column);

- Returns `true`, if `column` is in the half open interval `[start.column, end.column)`, otherwise `false`.

    bool Range.containsLine(int line);

- Returns `true`, if `line` is in the half open interval `[start.line, end.line)`, otherwise `false`.

    bool Range.overlaps(Range other);

- Returns `true`, if this range and the range `other` share a common region, otherwise `false`.

    bool Range.overlapsLine(int line);

- Returns `true`, if `line` is in the interval `[start.line, end.line]`, otherwise `false`.

    bool Range.overlapsColumn(int column);

- Returns `true`, if `column` is in the interval `[start.column, end.column]`, otherwise `false`.

    bool Range.onSingleLine();

- Returns `true`, if the range starts and ends at the same line, &ie; if `Range.start.line == Range.end.line`.

  Since: &kde; 4.9

    bool Range.equals(Range other);

- Returns `true`, if this range and the Range `other` are equal, otherwise `false`.

    String Range.toString();

- Returns the range as a string of the form `Range(Cursor(line, column), Cursor(line, column))`.

#### Global Functions

This section lists all global functions.

##### Reading & Including Files

    String read(String file);

- Will search the given `file` relative to the `katepart/script/files` directory and return its content as a string.

    void require(String file);

- Will search the given `file` relative to the `katepart/script/libraries` directory and evaluate it. `require` is internally guarded against multiple inclusions of the same `file`.

  Since: &kde; 4.10

##### Debugging

    void debug(String text);

- Prints `text` to `stdout` in the console launching the application.

##### Translation

In order to support full localization, there are several functions to translate strings in scripts, namely `i18n`, `i18nc`, `i18np` and `i18ncp`. These functions behave exactly like &kde;'s translation functions.

The translation functions translate the wrapped strings through &kde;'s translation system to the language used in the application. Strings in scripts being developed in the official &kappname; sources are automatically extracted and translatable. In other words, as a &kappname; developer you do not have to bother with message extraction and translation. However, for 3rd-party scripts developed outside of &kde;, you have to extract and translate the messages yourself. Along with your scripts you have to also distribute a translation catalog, that includes all translated strings. Further, your script header then must explicitly state the catalog to load by specifying `i18n-catalog`.

    void i18n(String text, arg1, ...);

- Translates `text` into the language used by the application. The arguments `arg1`, ..., are optional and used to replace the placeholders `%1`, `%2`, etc.

    void i18nc(String context, String text, arg1, ...);

- Translates `text` into the language used by the application. Additionally, the string `context` is visible to translators so they can provide a better translation. The arguments `arg1`, ..., are optional and used to replace the placeholders `%1`, `%2`, etc.

    void i18np(String singular, String plural, int number, arg1, ...);

- Translates either `singular` or `plural` into the language used by the application, depending on the given `number`. The arguments `arg1`, ..., are optional and used to replace the placeholders `%1`, `%2`, etc.

    void i18ncp(String context, String singular, String plural, int number, arg1, ...);

- Translates either `singular` or `plural` into the language used by the application, depending on the given `number`. Additionally, the string `context` is visible to translators so they can provide a better translation. The arguments `arg1`, ..., are optional and used to replace the placeholders `%1`, `%2`, etc.

#### The View API

Whenever a script is being executed, there is a global variable `view` representing the current active editor view. The following is a list of all available View functions.

    Cursor view.cursorPosition()

- Returns the current cursor position in the view.

    void view.setCursorPosition(int line, int column);
    void view.setCursorPosition(Cursor cursor);

- Set the current cursor position to either (line, column) or to the given cursor.

    Cursor view.virtualCursorPosition();

- Returns the virtual cursor position with each tab counting the corresponding amount of spaces depending on the current tab width.

    void view.setVirtualCursorPosition(int line, int column);
    void view.setVirtualCursorPosition(Cursor cursor);

- Set the current virtual cursor position to (line, column) or to the given cursor.

    String view.selectedText();

- Returns the selected text. If no text is selected, the returned string is empty.

    bool view.hasSelection();

- Returns `true`, if the view has selected text, otherwise `false`.

    Range view.selection();

- Returns the selected text range. The returned range is invalid if there is no selected text.

    void view.setSelection(Range range);

- Set the selected text to the given range.

    void view.removeSelectedText();

- Remove the selected text. If the view does not have any selected text, this does nothing.

    void view.selectAll();

- Selects the entire text in the document.

    void view.clearSelection();

- Clears the text selection without removing the text.

#### The Document API

Whenever a script is being executed, there is a global variable `document` representing the current active document. The following is a list of all available Document functions.

    String document.fileName();

- Returns the document's filename or an empty string for unsaved text buffers.

    String document.url();

- Returns the document's full url or an empty string for unsaved text buffers.

    String document.mimeType();

- Returns the document's mime type or the mime type `application/octet-stream` if no appropriate mime type could be found.

    String document.encoding();

- Returns the currently used encoding to save the file.

    String document.highlightingMode();

- Returns the global highlighting mode used for the whole document.

    String document.highlightingModeAt(Cursor pos);

- Returns the highlighting mode used at the given position in the document.

    Array document.embeddedHighlightingModes();

- Returns an array of highlighting modes embedded in this document.

    bool document.isModified();

- Returns `true`, if the document has unsaved changes (modified), otherwise `false`.

    String document.text();

- Returns the entire content of the document in a single text string. Newlines are marked with the newline character `\n`.

    String document.text(int fromLine, int fromColumn, int toLine, int toColumn);
    String document.text(Cursor from, Cursor to);
    String document.text(Range range);

- Returns the text in the given range. It is recommended to use the cursor and range based version for better readability of the source code.

    String document.line(int line);

- Returns the given text line as string. The string is empty if the requested line is out of range.

    String document.wordAt(int line, int column);
    String document.wordAt(Cursor cursor);

- Returns the word at the given cursor position.

    Range document.wordRangeAt(int line, int column);
    Range document.wordRangeAt(Cursor cursor);

- Return the range of the word at the given cursor position. The returned range is invalid (see Range.isValid()), if the text position is after the end of a line. If there is no word at the given cursor, an empty range is returned.

  Since: &kde; 4.9

    String document.charAt(int line, int column);
    String document.charAt(Cursor cursor);

- Returns the character at the given cursor position.

    String document.firstChar(int line);

- Returns the first character in the given `line` that is not a whitespace. The first character is at column 0. If the line is empty or only contains whitespace characters, the returned string is empty.

    String document.lastChar(int line);

- Returns the last character in the given `line` that is not a whitespace. If the line is empty or only contains whitespace characters, the returned string is empty.

    bool document.isSpace(int line, int column);
    bool document.isSpace(Cursor cursor);

- Returns `true`, if the character at the given cursor position is a whitespace, otherwise `false`.

    bool document.matchesAt(int line, int column, String text);
    bool document.matchesAt(Cursor cursor, String text);

- Returns `true`, if the given `text` matches at the corresponding cursor position, otherwise `false`.

    bool document.startsWith(int line, String text, bool skipWhiteSpaces);

- Returns `true`, if the line starts with `text`, otherwise `false`. The argument `skipWhiteSpaces` controls whether leading whitespaces are ignored.

    bool document.endsWith(int line, String text, bool skipWhiteSpaces);

- Returns `true`, if the line ends with `text`, otherwise `false`. The argument `skipWhiteSpaces` controls whether trailing whitespaces are ignored.

    bool document.setText(String text);

- Sets the entire document text.

    bool document.clear();

- Removes the entire text in the document.

    bool document.truncate(int line, int column);
    bool document.truncate(Cursor cursor);

- Truncate the given line at the given column or cursor position. Returns `true` on success, or `false` if the given line is not part of the document range.

    bool document.insertText(int line, int column, String text);
    bool document.insertText(Cursor cursor, String text);

- Inserts the `text` at the given cursor position. Returns `true` on success, or `false`, if the document is in read-only mode.

    bool document.removeText(int fromLine, int fromColumn, int toLine, int toColumn);
    bool document.removeText(Cursor from, Cursor to);
    bool document.removeText(Range range);

- Removes the text in the given range. Returns `true` on success, or `false`, if the document is in read-only mode.

    bool document.insertLine(int line, String text);

- Inserts text in the given line. Returns `true` on success, or `false`, if the document is in read-only mode or the line is not in the document range.

    bool document.removeLine(int line);

- Removes the given text line. Returns `true` on success, or `false`, if the document is in read-only mode or the line is not in the document range.

    bool document.wrapLine(int line, int column);
    bool document.wrapLine(Cursor cursor);

- Wraps the line at the given cursor position. Returns `true` on success, otherwise `false`, ⪚ if line < 0.

  Since: &kde; 4.9

    void document.joinLines(int startLine, int endLine);

- Joins the lines from `startLine` to `endLine`. Two succeeding text lines are always separated with a single space.

    int document.lines();

- Returns the number of lines in the document.

    int document.length();

- Returns the number of characters in the document.

    int document.lineLength(int line);

- Returns the `line`'s length.

    void document.editBegin();

- Starts an edit group for undo/redo grouping. Make sure to always call `editEnd()` as often as you call `editBegin()`. Calling `editBegin()` internally uses a reference counter, &ie;, this call can be nested.

    void document.editEnd();

- Ends an edit group. The last call of `editEnd()` (&ie; the one for the first call of `editBegin()`) finishes the edit step.

    int document.firstColumn(int line);

- Returns the first non-whitespace column in the given `line`. If there are only whitespaces in the line, the return value is `-1`.

    int document.lastColumn(int line);

- Returns the last non-whitespace column in the given `line`. If there are only whitespaces in the line, the return value is `-1`.

    int document.prevNonSpaceColumn(int line, int column);
    int document.prevNonSpaceColumn(Cursor cursor);

- Returns the column with a non-whitespace character starting at the given cursor position and searching backwards.

    int document.nextNonSpaceColumn(int line, int column);
    int document.nextNonSpaceColumn(Cursor cursor);

- Returns the column with a non-whitespace character starting at the given cursor position and searching forwards.

    int document.prevNonEmptyLine(int line);

- Returns the next non-empty line containing non-whitespace characters searching backwards.

    int document.nextNonEmptyLine(int line);

- Returns the next non-empty line containing non-whitespace characters searching forwards.

    bool document.isInWord(String character, int attribute);

- Returns `true`, if the given `character` with the given `attribute` can be part of a word, otherwise `false`.

    bool document.canBreakAt(String character, int attribute);

- Returns `true`, if the given `character` with the given `attribute` is suited to wrap a line, otherwise `false`.

    bool document.canComment(int startAttribute, int endAttribute);

- Returns `true`, if a range starting and ending with the given attributes is suited to be commented out, otherwise `false`.

    String document.commentMarker(int attribute);

- Returns the comment marker for single line comments for a given `attribute`.

    String document.commentStart(int attribute);

- Returns the comment marker for the start of multi-line comments for a given `attribute`.

    String document.commentEnd(int attribute);

- Returns the comment marker for the end of multi-line comments for a given `attribute`.

    int document.attribute(int line, int column);
    int document.attribute(Cursor cursor);

- Returns the attribute at the given cursor position.

    bool document.isAttribute(int line, int column, int attribute);
    bool document.isAttribute(Cursor cursor, int attribute);

- Returns `true`, if the attribute at the given cursor position equals `attribute`, otherwise `false`.

    String document.attributeName(int line, int column);
    String document.attributeName(Cursor cursor);

- Returns the attribute name as human readable text. This is equal to the `itemData` name in the syntax highlighting files.

    bool document.isAttributeName(int line, int column, String name);
    bool document.isAttributeName(Cursor cursor, String name);

- Returns `true`, if the attribute name at a certain cursor position matches the given `name`, otherwise `false`.

    String document.variable(String key);

- Returns the value of the requested document variable `key`. If the document variable does not exist, the return value is an empty string.

    String document.setVariable(String key, String value);

- Set the value of the requested document variable `key`. Returns the value of the set variable.

  See also: Kate document variables

  Since: &kde; 4.8

    int document.firstVirtualColumn(int line);

- Returns the virtual column of the first non-whitespace character in the given line or `-1`, if the line is empty or contains only whitespace characters.

    int document.lastVirtualColumn(int line);

- Returns the virtual column of the last non-whitespace character in the given line or `-1`, if the line is empty or contains only whitespace characters.

    int document.toVirtualColumn(int line, int column);
    int document.toVirtualColumn(Cursor cursor);
    Cursor document.toVirtualCursor(Cursor cursor);

- Converts the given real cursor position to a virtual cursor position, either returning an int or a Cursor object.

    int document.fromVirtualColumn(int line, int virtualColumn);
    int document.fromVirtualColumn(Cursor virtualCursor);
    Cursor document.fromVirtualCursor(Cursor virtualCursor);

- Converts the given virtual cursor position to a real cursor position, either returning an int or a Cursor object.

    Cursor document.anchor(int line, int column, Char character);
    Cursor document.anchor(Cursor cursor, Char character);

- Searches backward for the given character starting from the given cursor. As an example, if '(' is passed as character, this function will return the position of the opening '('. This reference counting, &ie; other '(...)' are ignored.

    Cursor document.rfind(int line, int column, String text, int attribute = -1);
    Cursor document.rfind(Cursor cursor, String text, int attribute = -1);

- Find searching backwards the given text with the appropriate `attribute`. The argument `attribute` is ignored if it is set to `-1`. The returned cursor is invalid, if the text could not be found.

    int document.defStyleNum(int line, int column);
    int document.defStyleNum(Cursor cursor);

- Returns the default style used at the given cursor position.

    bool document.isCode(int line, int column);
    bool document.isCode(Cursor cursor);

- Returns `true`, if the attribute at the given cursor position is not equal to all of the following styles: `dsComment`, `dsString`, `dsRegionMarker`, `dsChar`, `dsOthers`.

    bool document.isComment(int line, int column);
    bool document.isComment(Cursor cursor);

- Returns `true`, if the attribute of the character at the cursor position is `dsComment`, otherwise `false`.

    bool document.isString(int line, int column);
    bool document.isString(Cursor cursor);

- Returns `true`, if the attribute of the character at the cursor position is `dsString`, otherwise `false`.

    bool document.isRegionMarker(int line, int column);
    bool document.isRegionMarker(Cursor cursor);

- Returns `true`, if the attribute of the character at the cursor position is `dsRegionMarker`, otherwise `false`.

    bool document.isChar(int line, int column);
    bool document.isChar(Cursor cursor);

- Returns `true`, if the attribute of the character at the cursor position is `dsChar`, otherwise `false`.

    bool document.isOthers(int line, int column);
    bool document.isOthers(Cursor cursor);

- Returns `true`, if the attribute of the character at the cursor position is `dsOthers`, otherwise `false`.

## Editor Component Extensions

Editor Component Extensions extend KatePart, the Advanced Text Editor component used within many &kde; applications, such as &kate;, &kwrite;, Kile, and KDevelop. Creating an Editor Component Plugin will allow you to extend the editor's functionality in any and all of these programs.

To get started, see the KTextEditor Plugin Tutorial on &kde; TechBase. For even more, see the Advanced Tutorial, also on TechBase.

You can find the complete API documentation in the &kde; API Reference.

## &kate; (C++) Application Plugins

Kate Application Plugins extend the functionality of the &kate; editor itself in any way you can imagine, using the same programming language &kate; is written in, C++.

To get started, see the Writing a &kate; Plugin tutorial on the &kate; website. There is also a classic Hello, world! example plugin included with the &kate; source code.

## &pate; Python Plugins

&pate; Plugins also allow you to extend the functionality of &kate; in any way you like, using the Python programming language.

To get started, see the Python plugin developer guide on the &kate; website.

You can also access the API reference in the &pate; Configuration screen.