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CodeMirror: User Manual
{ } CodeMirror
/* User manual and
reference guide */
Overview
CodeMirror is a code-editor component that can be embedded in
Web pages. The code library provides only the editor
component, no accompanying buttons, auto-completion, or other IDE
functionality. It does provide a rich API on top of which such
functionality can be straightforwardly implemented. See
the add-ons included in the distribution,
and
the CodeMirror
UI project, for reusable implementations of extra features.
CodeMirror works with language-specific modes. Modes are
JavaScript programs that help color (and optionally indent) text
written in a given language. The distribution comes with a number
of modes (see the mode/ directory), and it isn't hard
to write new ones for other languages.
Basic Usage
The easiest way to use CodeMirror is to simply load the script
and style sheet found under lib/ in the distribution,
plus a mode script from one of the mode/ directories
and a theme stylesheet from theme/. (See
also the compression helper.) For
example:
<script src="lib/codemirror.js"></script>
<link rel="stylesheet" href="../lib/codemirror.css">
<script src="mode/javascript/javascript.js"></script>
Having done this, an editor instance can be created like
this:
var myCodeMirror = CodeMirror(document.body);
The editor will be appended to the document body, will start
empty, and will use the mode that we loaded. To have more control
over the new editor, a configuration object can be passed
to CodeMirror as a second argument:
var myCodeMirror = CodeMirror(document.body, {
value: "function myScript(){return 100;}\n",
mode: "javascript"
});
This will initialize the editor with a piece of code already in
it, and explicitly tell it to use the JavaScript mode (which is
useful when multiple modes are loaded).
See below for a full discussion of the
configuration options that CodeMirror accepts.
In cases where you don't want to append the editor to an
element, and need more control over the way it is inserted, the
first argument to the CodeMirror function can also
be a function that, when given a DOM element, inserts it into the
document somewhere. This could be used to, for example, replace a
textarea with a real editor:
var myCodeMirror = CodeMirror(function(elt) {
myTextArea.parentNode.replaceChild(elt, myTextArea);
}, {value: myTextArea.value});
However, for this use case, which is a common way to use
CodeMirror, the library provides a much more powerful
shortcut:
var myCodeMirror = CodeMirror.fromTextArea(myTextArea);
This will, among other things, ensure that the textarea's value
is updated when the form (if it is part of a form) is submitted.
See the API reference for a full
description of this method.
Configuration
Both the CodeMirror function and
its fromTextArea method take as second (optional)
argument an object containing configuration options. Any option
not supplied like this will be taken
from CodeMirror.defaults, an object containing the
default options. You can update this object to change the defaults
on your page.
Options are not checked in any way, so setting bogus option
values is bound to lead to odd errors.
These are the supported options:
value (string)- The starting value of the editor.
mode (string or object)- The mode to use. When not given, this will default to the
first mode that was loaded. It may be a string, which either
simply names the mode or is
a MIME type
associated with the mode. Alternatively, it may be an object
containing configuration options for the mode, with
a
name property that names the mode (for
example {name: "javascript", json: true}). The demo
pages for each mode contain information about what configuration
parameters the mode supports. You can ask CodeMirror which modes
and MIME types are loaded with
the CodeMirror.listModes
and CodeMirror.listMIMEs functions.
theme (string)- The theme to style the editor with. You must make sure the
CSS file defining the corresponding
.cm-s-[name]
styles is loaded (see
the theme directory in the
distribution). The default is "default", for which
colors are included in codemirror.css. It is
possible to use multiple theming classes at once—for
example "foo bar" will assign both
the cm-s-foo and the cm-s-bar classes
to the editor.
indentUnit (integer)- How many spaces a block (whatever that means in the edited
language) should be indented. The default is 2.
smartIndent (boolean)- Whether to use the context-sensitive indentation that the
mode provides (or just indent the same as the line before).
Defaults to true.
tabSize (integer)- The width of a tab character. Defaults to 4.
indentWithTabs (boolean)- Whether, when indenting, the first N*
tabSize
spaces should be replaced by N tabs. Default is false.
electricChars (boolean)- Configures whether the editor should re-indent the current
line when a character is typed that might change its proper
indentation (only works if the mode supports indentation).
Default is true.
autoClearEmptyLines (boolean)- When turned on (default is off), this will
automatically clear lines consisting only of whitespace when the
cursor leaves them. This is mostly useful to prevent auto
indentation from introducing trailing whitespace in a file.
keyMap (string)- Configures the keymap to use. The default
is
"default", which is the only keymap defined
in codemirror.js itself. Extra keymaps are found in
the keymap directory. See
the section on keymaps for more
information.
extraKeys (object)- Can be used to specify extra keybindings for the editor,
alongside the ones defined
by
keyMap. Should be
either null, or a valid keymap value.
lineWrapping (boolean)- Whether CodeMirror should scroll or wrap for long lines.
Defaults to
false (scroll).
lineNumbers (boolean)- Whether to show line numbers to the left of the editor.
firstLineNumber (integer)- At which number to start counting lines. Default is 1.
lineNumberFormatter (function(integer))- A function used to format line numbers. The function is passed the current line number. Default prints the line number verbatim.
gutter (boolean)- Can be used to force a 'gutter' (empty space on the left of
the editor) to be shown even when no line numbers are active.
This is useful for setting markers.
fixedGutter (boolean)- When enabled (off by default), this will make the gutter
stay visible when the document is scrolled horizontally.
readOnly (boolean)- This disables editing of the editor content by the user. If
the special value
"nocursor" is given (instead of
simply true), focusing of the editor is also
disallowed.
onChange (function)- When given, this function will be called every time the
content of the editor is changed. It will be given the editor
instance as first argument, and an
{from, to, text, next}
object containing information about the changes
that occurred as second argument. from
and to are the positions (in the pre-change
coordinate system) where the change started and
ended (for example, it might be {ch:0, line:18} if the
position is at the beginning of line #19). text
is an array of strings representing the text that replaced the changed
range (split by line). If multiple changes happened during a single
operation, the object will have a next property pointing to
another change object (which may point to another, etc).
onCursorActivity (function)- Will be called when the cursor or selection moves, or any
change is made to the editor content.
onViewportChange (function)- When given, will be called whenever
the view port of the editor changes
(due to scrolling, editing, or any other factor). It will be
passed three arguments, the editor instance, the start of the
viewport, and its end.
onGutterClick (function)- When given, will be called whenever the editor gutter (the
line-number area) is clicked. Will be given the editor instance
as first argument, the (zero-based) number of the line that was
clicked as second argument, and the raw
mousedown
event object as third argument.
onFocus, onBlur (function)- The given functions will be called whenever the editor is
focused or unfocused.
onScroll (function)- When given, will be called whenever the editor is
scrolled.
onUpdate (function)- Will be called whenever CodeMirror updates its DOM display.
matchBrackets (boolean)- Determines whether brackets are matched whenever the cursor
is moved next to a bracket.
cursorBlinkRate (number)- Half-period in milliseconds used for cursor blinking. The default blink
rate is 530ms.
workTime, workDelay (number)- Highlighting is done by a pseudo background-thread that will
work for
workTime milliseconds, and then use
timeout to sleep for workDelay milliseconds. The
defaults are 200 and 300, you can change these options to make
the highlighting more or less aggressive.
pollInterval (number)- Indicates how quickly CodeMirror should poll its input
textarea for changes. Most input is captured by events, but some
things, like IME input on some browsers, doesn't generate events
that allow CodeMirror to properly detect it. Thus, it polls.
Default is 100 milliseconds.
undoDepth (integer)- The maximum number of undo levels that the editor stores.
Defaults to 40.
tabindex (integer)- The tab
index to assign to the editor. If not given, no tab index
will be assigned.
autofocus (boolean)- Can be used to make CodeMirror focus itself on
initialization. Defaults to off.
When
fromTextArea is
used, and no explicit value is given for this option, it will be
set to true when either the source textarea is focused, or it
has an autofocus attribute and no other element is
focused.
dragDrop (boolean)- Controls whether drag-and-drop is enabled. On by default.
onDragEvent (function)- When given, this will be called when the editor is handling
a
dragenter, dragover,
or drop event. It will be passed the editor instance
and the event object as arguments. The callback can choose to
handle the event itself, in which case it should
return true to indicate that CodeMirror should not
do anything further.
onKeyEvent (function)- This provides a rather low-level hook into CodeMirror's key
handling. If provided, this function will be called on
every
keydown, keyup,
and keypress event that CodeMirror captures. It
will be passed two arguments, the editor instance and the key
event. This key event is pretty much the raw key event, except
that a stop() method is always added to it. You
could feed it to, for example, jQuery.Event to
further normalize it.
This function can inspect the key
event, and handle it if it wants to. It may return true to tell
CodeMirror to ignore the event. Be wary that, on some browsers,
stopping a keydown does not stop
the keypress from firing, whereas on others it
does. If you respond to an event, you should probably inspect
its type property and only do something when it
is keydown (or keypress for actions
that need character data).
Keymaps
Keymaps are ways to associate keys with functionality. A keymap
is an object mapping strings that identify the keys to functions
that implement their functionality.
Keys are identified either by name or by character.
The CodeMirror.keyNames object defines names for
common keys and associates them with their key codes. Examples of
names defined here are Enter, F5,
and Q. These can be prefixed
with Shift-, Cmd-, Ctrl-,
and Alt- (in that order!) to specify a modifier. So
for example, Shift-Ctrl-Space would be a valid key
identifier.
Alternatively, a character can be specified directly by
surrounding it in single quotes, for example '$'
or 'q'. Due to limitations in the way browsers fire
key events, these may not be prefixed with modifiers.
The CodeMirror.keyMap object associates keymaps
with names. User code and keymap definitions can assign extra
properties to this object. Anywhere where a keymap is expected, a
string can be given, which will be looked up in this object. It
also contains the "default" keymap holding the
default bindings.
The values of properties in keymaps can be either functions of
a single argument (the CodeMirror instance), strings, or
false. Such strings refer to properties of the
CodeMirror.commands object, which defines a number of
common commands that are used by the default keybindings, and maps
them to functions. If the property is set to false,
CodeMirror leaves handling of the key up to the browser. A key
handler function may throw CodeMirror.Pass to indicate
that it has decided not to handle the key, and other handlers (or
the default behavior) should be given a turn.
Keys mapped to command names that start with the
characters "go" (which should be used for
cursor-movement actions) will be fired even when an
extra Shift modifier is present (i.e. "Up":
"goLineUp" matches both up and shift-up). This is used to
easily implement shift-selection.
Keymaps can defer to each other by defining
a fallthrough property. This indicates that when a
key is not found in the map itself, one or more other maps should
be searched. It can hold either a single keymap or an array of
keymaps.
When a keymap contains a nofallthrough property
set to true, keys matched against that map will be
ignored if they don't match any of the bindings in the map (no
further child maps will be tried, and the default effect of
inserting a character will not occur).
Customized Styling
Up to a certain extent, CodeMirror's look can be changed by
modifying style sheet files. The style sheets supplied by modes
simply provide the colors for that mode, and can be adapted in a
very straightforward way. To style the editor itself, it is
possible to alter or override the styles defined
in codemirror.css.
Some care must be taken there, since a lot of the rules in this
file are necessary to have CodeMirror function properly. Adjusting
colors should be safe, of course, and with some care a lot of
other things can be changed as well. The CSS classes defined in
this file serve the following roles:
CodeMirror- The outer element of the editor. This should be used for the
editor width, borders and positioning. Can also be used to set
styles that should hold for everything inside the editor (such
as font and font size), or to set a background.
CodeMirror-scroll- This determines the editor's height, and whether the editor
scrolls (
overflow: auto + fixed height). By
default, it does. Giving this height: auto; overflow:
visible; will cause the editor to resize to fit its
content.
CodeMirror-focused- Whenever the editor is focused, the top element gets this
class. This is used to hide the cursor and give the selection a
different color when the editor is not focused.
CodeMirror-gutter- Use this for giving a background or a border to the editor
gutter. Don't set any padding here,
use
CodeMirror-gutter-text for that. By default,
the gutter is 'fluid', meaning it will adjust its width to the
maximum line number or line marker width. You can also set a
fixed width if you want.
CodeMirror-gutter-text- Used to style the actual line numbers. For the numbers to
line up, you must make sure that the font in the gutter is the
same as the one in the rest of the editor, so you should
probably only set font style and size in
the
CodeMirror class.
CodeMirror-lines- The visible lines. If this has vertical
padding,
CodeMirror-gutter should have the same
padding.
CodeMirror-cursor- The cursor is a block element that is absolutely positioned.
You can make it look whichever way you want.
CodeMirror-selected- The selection is represented by
span elements
with this class.
CodeMirror-matchingbracket,
CodeMirror-nonmatchingbracket- These are used to style matched (or unmatched) brackets.
So note carefully that, in order to resize the
editor, you should set a width on
the wrapper
(class CodeMirror) element, and a height on
the scroller
(class CodeMirror-scroll) element.
The actual lines, as well as the cursor, are represented
by pre elements. By default no text styling (such as
bold) that might change line height is applied. If you do want
such effects, you'll have to give CodeMirror pre a
fixed height.
If your page's style sheets do funky things to
all div or pre elements (you probably
shouldn't do that), you'll have to define rules to cancel these
effects out again for elements under the CodeMirror
class.
Themes are also simply CSS files, which define colors for
various syntactic elements. See the files in
the theme directory.
Programming API
A lot of CodeMirror features are only available through its API.
This has the disadvantage that you need to do work to enable them,
and the advantage that CodeMirror will fit seamlessly into your
application.
Whenever points in the document are represented, the API uses
objects with line and ch properties.
Both are zero-based. CodeMirror makes sure to 'clip' any positions
passed by client code so that they fit inside the document, so you
shouldn't worry too much about sanitizing your coordinates. If you
give ch a value of null, or don't
specify it, it will be replaced with the length of the specified
line.
getValue() → string- Get the current editor content. You can pass it an optional
argument to specify the string to be used to separate lines
(defaults to
"\n").
setValue(string)- Set the editor content.
getSelection() → string- Get the currently selected code.
replaceSelection(string)- Replace the selection with the given string.
setSize(width, height)- Programatically set the size of the editor (overriding the
applicable CSS
rules).
width and height height
can be either numbers (interpreted as pixels) or CSS units
("100%", for example). You can
pass null for either of them to indicate that that
dimension should not be changed.
focus()- Give the editor focus.
scrollTo(x, y)- Scroll the editor to a given (pixel) position. Both
arguments may be left as
null
or undefined to have no effect.
getScrollInfo()- Get an
{x, y, width, height} object that
represents the current scroll position and scrollable area size
of the editor.
scrollIntoView(pos)- Scrolls the given
{line, ch} position into
view. If no argument is given, this will scroll the cursor into
view.
setOption(option, value)- Change the configuration of the editor.
option
should the name of an option,
and value should be a valid value for that
option.
getOption(option) → value- Retrieves the current value of the given option for this
editor instance.
getMode() → object- Gets the mode object for the editor. Note that this is
distinct from
getOption("mode"), which gives you
the mode specification, rather than the resolved, instantiated
mode object.
cursorCoords(start, mode) → object- Returns an
{x, y, yBot} object containing the
coordinates of the cursor. If mode
is "local", they will be relative to the top-left
corner of the editable document. If it is "page" or
not given, they are relative to the top-left corner of the
page. yBot is the coordinate of the bottom of the
cursor. start is a boolean indicating whether you
want the start or the end of the selection.
charCoords(pos, mode) → object- Like
cursorCoords, but returns the position of
an arbitrary characters. pos should be
a {line, ch} object.
coordsChar(object) → pos- Given an
{x, y} object (in page coordinates),
returns the {line, ch} position that corresponds to
it.
defaultTextHeight() → number- Returns the line height of the default font for the editor.
undo()- Undo one edit (if any undo events are stored).
redo()- Redo one undone edit.
historySize() → object- Returns an object with
{undo, redo} properties,
both of which hold integers, indicating the amount of stored
undo and redo operations.
clearHistory()- Clears the editor's undo history.
getHistory() → object- Get a (JSON-serializeable) representation of the undo history.
setHistory(object)- Replace the editor's undo history with the one provided,
which must be a value as returned
by
getHistory. Note that
this will have entirely undefined results if the editor content
isn't also the same as it was when getHistory was
called.
indentLine(line, dir)- Reset the given line's indentation to the indentation
prescribed by the mode. If the second argument is given,
indentation will be increased (if
dir is true) or
decreased (if false) by an indent
unit instead.
getTokenAt(pos) → object- Retrieves information about the token the current mode found
before the given position (a
{line, ch} object). The
returned object has the following properties:
start- The character (on the given line) at which the token starts.
end- The character at which the token ends.
string- The token's string.
className- The class the mode assigned
to the token. (Can be null when no class was assigned.)
state- The mode's state at the end of this token.
markText(from, to, className, options) → object- Can be used to mark a range of text with a specific CSS
class name.
from and to should
be {line, ch} objects. The options
parameter is optional. When given, it should be an object that
may contain the following configuration options:
inclusiveLeft- Determines whether
text inserted on the left of the marker will end up inside
or outside of it.
inclusiveRight- Like
inclusiveLeft,
but for the right side.
startStyle- Can be used to specify
an extra CSS class to be applied to the leftmost span that
is part of the marker.
endStyle- Equivalent
to
startStyle, but for the rightmost span.
The method will return an object with two methods,
clear(), which removes the mark,
and find(), which returns a {from, to}
(both document positions), indicating the current position of
the marked range, or undefined if the marker is no
longer in the document.
setBookmark(pos) → object- Inserts a bookmark, a handle that follows the text around it
as it is being edited, at the given position. A bookmark has two
methods
find() and clear(). The first
returns the current position of the bookmark, if it is still in
the document, and the second explicitly removes the
bookmark.
findMarksAt(pos) → array- Returns an array of all the bookmarks and marked ranges
present at the given position.
setMarker(line, text, className) → lineHandle- Add a gutter marker for the given line. Gutter markers are
shown in the line-number area (instead of the number for this
line). Both
text and className are
optional. Setting text to a Unicode character like
● tends to give a nice effect. To put a picture in the gutter,
set text to a space and className to
something that sets a background image. If you
specify text, the given text (which may contain
HTML) will, by default, replace the line number for that line.
If this is not what you want, you can include the
string %N% in the text, which will be replaced by
the line number.
clearMarker(line)- Clears a marker created
with
setMarker. line can be either a
number or a handle returned by setMarker (since a
number may now refer to a different line if something was added
or deleted).
setLineClass(line, className, backgroundClassName) → lineHandle- Set a CSS class name for the given line.
line
can be a number or a line handle (as returned
by setMarker or this
function). className will be used to style the text
for the line, and backgroundClassName to style its
background (which lies behind the selection).
Pass null to clear the classes for a line.
hideLine(line) → lineHandle- Hide the given line (either by number or by handle). Hidden
lines don't show up in the editor, and their numbers are skipped
when line numbers are enabled.
Deleting a region around them does delete them, and coping a
region around will include them in the copied text.
showLine(line) → lineHandle- The inverse of
hideLine—re-shows a previously
hidden line, by number or by handle.
onDeleteLine(line, func)- Register a function that should be called when the line is
deleted from the document.
lineInfo(line) → object- Returns the line number, text content, and marker status of
the given line, which can be either a number or a handle
returned by
setMarker. The returned object has the
structure {line, handle, text, markerText, markerClass,
lineClass, bgClass}.
getLineHandle(num) → lineHandle- Fetches the line handle for the given line number.
getViewport() → object- Returns a
{from, to} object indicating the
start (inclusive) and end (exclusive) of the currently displayed
part of the document. In big documents, when most content is
scrolled out of view, CodeMirror will only render the visible
part, and a margin around it. See also
the onViewportChange
option.
addWidget(pos, node, scrollIntoView)- Puts
node, which should be an absolutely
positioned DOM node, into the editor, positioned right below the
given {line, ch} position.
When scrollIntoView is true, the editor will ensure
that the entire node is visible (if possible). To remove the
widget again, simply use DOM methods (move it somewhere else, or
call removeChild on its parent).
matchBrackets()- Force matching-bracket-highlighting to happen.
lineCount() → number- Get the number of lines in the editor.
getCursor(start) → objectstart is a boolean indicating whether the start
or the end of the selection must be retrieved. If it is not
given, the current cursor pos, i.e. the side of the selection
that would move if you pressed an arrow key, is chosen.
A {line, ch} object will be returned.somethingSelected() → boolean- Return true if any text is selected.
setCursor(pos)- Set the cursor position. You can either pass a
single
{line, ch} object, or the line and the
character as two separate parameters.
setSelection(start, end)- Set the selection range.
start
and end should be {line, ch} objects.
getLine(n) → string- Get the content of line
n.
setLine(n, text)- Set the content of line
n.
removeLine(n)- Remove the given line from the document.
getRange(from, to) → string
- Get the text between the given points in the editor, which
should be
{line, ch} objects. An optional third
argument can be given to indicate the line separator string to
use (defaults to "\n").
replaceRange(string, from, to)- Replace the part of the document between
from
and to with the given string. from
and to must be {line, ch}
objects. to can be left off to simply insert the
string at position from.
posFromIndex(index) → object- Calculates and returns a
{line, ch} object for a
zero-based index who's value is relative to the start of the
editor's text. If the index is out of range of the text then
the returned object is clipped to start or end of the text
respectively.
indexFromPos(object) → number- The reverse of
posFromIndex.
The following are more low-level methods:
operation(func) → result- CodeMirror internally buffers changes and only updates its
DOM structure after it has finished performing some operation.
If you need to perform a lot of operations on a CodeMirror
instance, you can call this method with a function argument. It
will call the function, buffering up all changes, and only doing
the expensive update after the function returns. This can be a
lot faster. The return value from this method will be the return
value of your function.
compoundChange(func) → result- Will call the given function (and return its result),
combining all changes made while that function executes into a
single undo event.
refresh()- If your code does something to change the size of the editor
element (window resizes are already listened for), or unhides
it, you should probably follow up by calling this method to
ensure CodeMirror is still looking as intended.
getInputField() → textarea- Returns the hidden textarea used to read input.
getWrapperElement() → node- Returns the DOM node that represents the editor, and
controls its width. Remove this from your tree to delete an
editor instance. Set it's
width style when
resizing.
getScrollerElement() → node- Returns the DOM node that is responsible for the vertical
sizing and horizontal scrolling of the editor. You can change
the
height style of this element to resize an
editor. (You might have to call
the refresh method
afterwards.)
getGutterElement() → node- Fetches the DOM node that represents the editor gutter.
getStateAfter(line) → state- Returns the mode's parser state, if any, at the end of the
given line number. If no line number is given, the state at the
end of the document is returned. This can be useful for storing
parsing errors in the state, or getting other kinds of
contextual information for a line.
The CodeMirror object itself provides
several useful properties. Firstly, its version
property contains a string that indicates the version of the
library. For releases, this simply
contains "major.minor" (for
example "2.33". For beta versions, " B"
(space, capital B) is added at the end of the string, for
development snapshots, " +" (space, plus) is
added.
The CodeMirror.fromTextArea
method provides another way to initialize an editor. It takes a
textarea DOM node as first argument and an optional configuration
object as second. It will replace the textarea with a CodeMirror
instance, and wire up the form of that textarea (if any) to make
sure the editor contents are put into the textarea when the form
is submitted. A CodeMirror instance created this way has three
additional methods:
save()- Copy the content of the editor into the textarea.
toTextArea()- Remove the editor, and restore the original textarea (with
the editor's current content).
getTextArea() → textarea- Returns the textarea that the instance was based on.
If you want to define extra methods in terms
of the CodeMirror API, it is possible to
use CodeMirror.defineExtension(name, value). This
will cause the given value (usually a method) to be added to all
CodeMirror instances created from then on.
If your extention just needs to run some
code whenever a CodeMirror instance is initialized,
use CodeMirror.defineInitHook. Give it a function as
its only argument, and from then on, that function will be called
(with the instance as argument) whenever a new CodeMirror instance
is initialized.
Add-ons
The lib/util directory in the distribution
contains a number of reusable components that implement extra
editor functionality. In brief, they are:
dialog.js- Provides a very simple way to query users for text input.
Adds an
openDialog method to CodeMirror instances,
which can be called with an HTML fragment that provides the
prompt (should include an input tag), and a
callback function that is called when text has been entered.
Depends on lib/util/dialog.css.
searchcursor.js- Adds the
getSearchCursor(query, start, caseFold) →
cursor method to CodeMirror instances, which can be used
to implement search/replace functionality. query
can be a regular expression or a string (only strings will match
across lines—if they contain newlines). start
provides the starting position of the search. It can be
a {line, ch} object, or can be left off to default
to the start of the document. caseFold is only
relevant when matching a string. It will cause the search to be
case-insensitive. A search cursor has the following methods:
findNext(), findPrevious() → boolean- Search forward or backward from the current position.
The return value indicates whether a match was found. If
matching a regular expression, the return value will be the
array returned by the
match method, in case you
want to extract matched groups.
from(), to() → object- These are only valid when the last call
to
findNext or findPrevious did
not return false. They will return {line, ch}
objects pointing at the start and end of the match.
replace(text)- Replaces the currently found match with the given text
and adjusts the cursor position to reflect the
replacement.
search.js- Implements the search commands. CodeMirror has keys bound to
these by default, but will not do anything with them unless an
implementation is provided. Depends
on
searchcursor.js, and will make use
of openDialog when
available to make prompting for search queries less ugly.
foldcode.js- Helps with code folding.
See the demo for an example.
Call
CodeMirror.newFoldFunction with a range-finder
helper function to create a function that will, when applied to
a CodeMirror instance and a line number, attempt to fold or
unfold the block starting at the given line. A range-finder is a
language-specific function that also takes an instance and a
line number, and returns an end line for the block, or null if
no block is started on that line. This file
provides CodeMirror.braceRangeFinder, which finds
blocks in brace languages (JavaScript, C, Java,
etc), CodeMirror.indentRangeFinder, for languages
where indentation determines block structure (Python, Haskell),
and CodeMirror.tagRangeFinder, for XML-style
languages.
runmode.js- Can be used to run a CodeMirror mode over text without
actually opening an editor instance.
See the demo for an
example.
overlay.js- Mode combinator that can be used to extend a mode with an
'overlay' — a secondary mode is run over the stream, along with
the base mode, and can color specific pieces of text without
interfering with the base mode.
Defines
CodeMirror.overlayMode, which is used to
create such a mode. See this
demo for a detailed example.
multiplex.js- Mode combinator that can be used to easily 'multiplex'
between several modes.
Defines
CodeMirror.multiplexingMode which, when
given as first argument a mode object, and as other arguments
any number of {open, close, mode [, delimStyle]}
objects, will return a mode object that starts parsing using the
mode passed as first argument, but will switch to another mode
as soon as it encounters a string that occurs in one of
the open fields of the passed objects. When in a
sub-mode, it will go back to the top mode again when
the close string is encountered.
When delimStyle is specified, it will be the token
style returned for the delimiter tokens. The outer mode will not
see the content between the delimiters.
See this demo for an
example.
simple-hint.js- Provides a framework for showing autocompletion hints.
Defines
CodeMirror.simpleHint, which takes a
CodeMirror instance and a hinting function, and pops up a widget
that allows the user to select a completion. Hinting functions
are function that take an editor instance, and return
a {list, from, to} object, where list
is an array of strings (the completions), and from
and to give the start and end of the token that is
being completed. Depends
on lib/util/simple-hint.css.
javascript-hint.js- Defines
CodeMirror.javascriptHint
and CodeMirror.coffeescriptHint, which are simple
hinting functions for the JavaScript and CoffeeScript
modes.
match-highlighter.js- Adds a
matchHighlight method to CodeMirror
instances that can be called (typically from
a onCursorActivity
handler) to highlight all instances of a currently selected word
with the a classname given as a first argument to the method.
Depends on
the searchcursor
add-on. Demo here.
formatting.js- Adds
commentRange, autoIndentRange,
and autoFormatRange methods that, respectively,
comment (or uncomment), indent, or format (add line breaks) a
range of code. Demo here.
closetag.js- Provides utility functions for adding automatic tag closing
to XML modes. See
the demo.
loadmode.js- Defines a
CodeMirror.requireMode(modename,
callback) function that will try to load a given mode and
call the callback when it succeeded. You'll have to
set CodeMirror.modeURL to a string that mode paths
can be constructed from, for
example "mode/%N/%N.js"—the %N's will
be replaced with the mode name. Also
defines CodeMirror.autoLoadMode(instance, mode),
which will ensure the given mode is loaded and cause the given
editor instance to refresh its mode when the loading
succeeded. See the demo.
Writing CodeMirror Modes
Modes typically consist of a single JavaScript file. This file
defines, in the simplest case, a lexer (tokenizer) for your
language—a function that takes a character stream as input,
advances it past a token, and returns a style for that token. More
advanced modes can also handle indentation for the language.
The mode script should
call CodeMirror.defineMode to register itself with
CodeMirror. This function takes two arguments. The first should be
the name of the mode, for which you should use a lowercase string,
preferably one that is also the name of the files that define the
mode (i.e. "xml" is defined xml.js). The
second argument should be a function that, given a CodeMirror
configuration object (the thing passed to
the CodeMirror function) and an optional mode
configuration object (as in
the mode option), returns
a mode object.
Typically, you should use this second argument
to defineMode as your module scope function (modes
should not leak anything into the global scope!), i.e. write your
whole mode inside this function.
The main responsibility of a mode script is parsing
the content of the editor. Depending on the language and the
amount of functionality desired, this can be done in really easy
or extremely complicated ways. Some parsers can be stateless,
meaning that they look at one element (token) of the code
at a time, with no memory of what came before. Most, however, will
need to remember something. This is done by using a state
object, which is an object that is always passed when
reading a token, and which can be mutated by the tokenizer.
Modes that use a state must define
a startState method on their mode object. This is a
function of no arguments that produces a state object to be used
at the start of a document.
The most important part of a mode object is
its token(stream, state) method. All modes must
define this method. It should read one token from the stream it is
given as an argument, optionally update its state, and return a
style string, or null for tokens that do not have to
be styled. For your styles, you can either use the 'standard' ones
defined in the themes (without the cm- prefix), or
define your own and have people include a custom CSS file for your
mode.
The stream object encapsulates a line of code
(tokens may never span lines) and our current position in that
line. It has the following API:
eol() → boolean- Returns true only if the stream is at the end of the
line.
sol() → boolean- Returns true only if the stream is at the start of the
line.
peek() → character- Returns the next character in the stream without advancing
it. Will return an empty string at the end of the line.
next() → character- Returns the next character in the stream and advances it.
Also returns
undefined when no more characters are
available.
eat(match) → charactermatch can be a character, a regular expression,
or a function that takes a character and returns a boolean. If
the next character in the stream 'matches' the given argument,
it is consumed and returned. Otherwise, undefined
is returned.eatWhile(match) → boolean- Repeatedly calls
eat with the given argument,
until it fails. Returns true if any characters were eaten.
eatSpace() → boolean- Shortcut for
eatWhile when matching
white-space.
skipToEnd()- Moves the position to the end of the line.
skipTo(ch) → boolean- Skips to the next occurrence of the given character, if
found on the current line (doesn't advance the stream if the
character does not occur on the line). Returns true if the
character was found.
match(pattern, consume, caseFold) → boolean- Act like a
multi-character
eat—if consume is true
or not given—or a look-ahead that doesn't update the stream
position—if it is false. pattern can be either a
string or a regular expression starting with ^.
When it is a string, caseFold can be set to true to
make the match case-insensitive. When successfully matching a
regular expression, the returned value will be the array
returned by match, in case you need to extract
matched groups.
backUp(n)- Backs up the stream
n characters. Backing it up
further than the start of the current token will cause things to
break, so be careful.
column() → integer- Returns the column (taking into account tabs) at which the
current token starts. Can be used to find out whether a token
starts a new line.
indentation() → integer- Tells you how far the current line has been indented, in
spaces. Corrects for tab characters.
current() → string- Get the string between the start of the current token and
the current stream position.
By default, blank lines are simply skipped when
tokenizing a document. For languages that have significant blank
lines, you can define a blankLine(state) method on
your mode that will get called whenever a blank line is passed
over, so that it can update the parser state.
Because state object are mutated, and CodeMirror
needs to keep valid versions of a state around so that it can
restart a parse at any line, copies must be made of state objects.
The default algorithm used is that a new state object is created,
which gets all the properties of the old object. Any properties
which hold arrays get a copy of these arrays (since arrays tend to
be used as mutable stacks). When this is not correct, for example
because a mode mutates non-array properties of its state object, a
mode object should define a copyState method,
which is given a state and should return a safe copy of that
state.
If you want your mode to provide smart indentation
(through the indentLine
method and the indentAuto
and newlineAndIndent commands, which keys can be
bound to), you must define
an indent(state, textAfter) method on your mode
object.
The indentation method should inspect the given state object,
and optionally the textAfter string, which contains
the text on the line that is being indented, and return an
integer, the amount of spaces to indent. It should usually take
the indentUnit
option into account.
Finally, a mode may define
an electricChars property, which should hold a string
containing all the characters that should trigger the behaviour
described for
the electricChars
option.
So, to summarize, a mode must provide
a token method, and it may
provide startState, copyState,
compareStates, and indent methods. For
an example of a trivial mode, see
the diff mode, for a more involved
example, see the C-like
mode.
Sometimes, it is useful for modes to nest—to have one
mode delegate work to another mode. An example of this kind of
mode is the mixed-mode HTML
mode. To implement such nesting, it is usually necessary to
create mode objects and copy states yourself. To create a mode
object, there are CodeMirror.getMode(options,
parserConfig), where the first argument is a configuration
object as passed to the mode constructor function, and the second
argument is a mode specification as in
the mode option. To copy a
state object, call CodeMirror.copyState(mode, state),
where mode is the mode that created the given
state.
In a nested mode, it is recommended to add an
extra methods, innerMode which, given a state object,
returns a {state, mode} object with the inner mode
and its state for the current position. These are used by utility
scripts such as the autoformatter
and the tag closer to get context
information. Use the CodeMirror.innerMode helper
function to, starting from a mode and a state, recursively walk
down to the innermost mode and state.
To make indentation work properly in a nested parser, it is
advisable to give the startState method of modes that
are intended to be nested an optional argument that provides the
base indentation for the block of code. The JavaScript and CSS
parser do this, for example, to allow JavaScript and CSS code
inside the mixed-mode HTML mode to be properly indented.
Finally, it is possible to associate your mode, or a certain
configuration of your mode, with
a MIME type. For
example, the JavaScript mode associates itself
with text/javascript, and its JSON variant
with application/json. To do this,
call CodeMirror.defineMIME(mime, modeSpec),
where modeSpec can be a string or object specifying a
mode, as in the mode
option.
Sometimes, it is useful to add or override mode
object properties from external code.
The CodeMirror.extendMode can be used to add
properties to mode objects produced for a specific mode. Its first
argument is the name of the mode, its second an object that
specifies the properties that should be added. This is mostly
useful to add utilities that can later be looked
up getMode.