Syntax Mode Definition

Syntax Mode Definition

The syntax modes in MonoDevelop are defined using XML. These XMLs can be extended by:

  • Adding the xml file to the Mono.TextEditor assembly as resource
  • Letting an addin (for example language binding) add the xml file/resource via the addin tree (/MonoDevelop/SourceEditor2/SyntaxModes)
  • Put the xml file into the ~/.config/MonoDevelop/syntaxmodes directory, and MonoDevelop will load it automatically (C:\Users\$USER\AppData\Roaming\MonoDevelop\syntaxmodes on Windows Vista, and C:\Documents and Settings\Users\$USER\Application Data\MonoDevelop\syntaxmodes on Windows XP). This is where files that you add via the GUI in the preferences dialog are copied.

Adding syntax mode via the addin tree

There are two options how a syntax mode xml can be provided:

  • Per file name. Give the path relative to the addin dll

<Templates file="RELATIVE_PATH_OF_THE_XML"/>

  • As resource embedded in the addin dll

<Templates resource="NAME_OF_THE_RESOURCE"/>

The syntax mode extension path is ”/MonoDevelop/SourceEditor2/SyntaxModes”.

I would recommend giving us the syntax mode. I’ll put it into the texteditor dll and then monodevelop has more languages it supports.

Syntax Mode Xml

Each syntax mode xml needs to contain one SyntaxMode tag. All other nodes are placed into this tag. The SyntaxMode tag defines a name for the mode (e.g. the language it highlights in human readable form) and the mime type the syntax mode applies to:

<SyntaxMode name = "C#" mimeTypes="text/x-csharp">


Note: It can be specified more than one mime type, seperated by ‘;’.

Mime Types

It may be that you have to add the mime type, because it is unknown. MonoDevelop has an own mime type definition method using the addin tree. How the mime type system works should be part of a seperate article. However to make it short here an example of the il mime type definiton:

<Extension path = "/MonoDevelop/Core/MimeTypes">
  <MimeType id="text/x-ilasm" _description="il files" isText="true">
    <File pattern="*.il" />

When adding own mime types just add your type to this addin file (or to your addin):


The EolSpan Tag

The EolSpan tag is a short form of the Span tag. The difference is that it has only a begin string and it ends at end of line. The tag content is the begin string. All attributes that are valid for the Span tag can be applied to EolSpan tags too.

Example for C# line comments:

<EolSpan color = "comment.line" rule="Comment" tagColor="comment.tag.line">//</EolSpan>

The eol span looks in a source file like this: ss-eolSpan.png

The Keywords Tag

The Keywords tag specifies a list of keywords to be highlighted. The Keywords tag has following attributes:

Attribute Required Description
color yes The color of the keywords.
ignorecase no If true, the case of the keywords is ignored. If the tag is not specified the ignorecase from the rules in which the keywords are defined are taken.

The Keywords are defined by Word tags that are childs of the Keywords tag.

Example from VB.NET syntax mode:

<Keywords color = "keyword.selection">


If inside key words are some non letter/digit chars used it may be required to specify special delimiters for that syntax mode. Delimiters are the chars between the keywords. The standard delimiters are: &()\<\>{}[]~!%^\*-+=|\\\\\#/:;\\"' ,\\t.?. Each rule can specify different delimiters. Delimiters are specified using the Delimiters tag and a string.

For example:

<Delimiters>&amp;&lt;&gt;~!@%^*()-+=|\#/{}[]:;"' ,    ?</Delimiters>


At the point of writing following colors can be used for the keywords. Note that due to the MonoDevelop styles it is currently not possible to define own colors (But you can request some). The syntax mode definitions should make rich use of these color definitions. It’s up to the syntax styles if the highlighted source looks more colorful or not.

General text colors:

  • text
  • text.punctuation
  • text.preprocessor
  • text.preprocessor.keyword
  • text.markup
  • text.markup.tag

Colors used by comments:

  • comment
  • comment.line
  • comment.block
  • comment.doc
  • comment.tag
  • comment.tag.line
  • comment.tag.block
  • comment.tag.doc
  • comment.keyword
  • comment.keyword.todo

Colors for strings:

  • string
  • string.single
  • string.double
  • string.other

Colors for constants:

  • constant
  • constant.digit
  • constant.language
  • constant.language.void

Colors for keywords:

  • keyword
  • keyword.access
  • keyword.operator
  • keyword.operator.declaration
  • keyword.selection
  • keyword.iteration
  • keyword.jump
  • keyword.context
  • keyword.exceptions
  • keyword.modifier
  • keyword.type
  • keyword.namespace
  • keyword.declaration
  • keyword.parameter
  • keyword.misc

The Match Tag

A match is simply a regular expression that is colorized. An example for this are numbers. The match content is the regular expression to match and the match has only one attribute: color (See the Keywords section for a list of colors).

Note that you’ll find ‘CSharpNumber’ as content of the Match tags. This is a hard coded regular expression for C# numbers. Its faster than using the regex engine of C#. Unfortunately the regex engine only works on strings and not on custom character sequences. Therefore the perfomance penalty of regexes can be too high in some cases.

The Property Tag

A property is a key/value pair. The Property tag inside a syntax mode specifies language specific properties that are used by some of MonoDevelop’s commands. They don’t directly influence the syntax highlighting.

At the point of writing following properties can be defined:

Property Description
LineComment The tag that starts a single line (comment to end of line) comment.
BlockCommentStart The tag that starts a block comment.
BlockCommentEnd The tag that ends a block comment.
StringQuote The quotation mark

Note that a property is always a list. Multiple line comments can be defined by specifying more than one LineComment property.

In C# syntax a property in the MonoDevelop syntax mode is: KeyValuePair<string, List<string>>

Example properties from the C# backend binding:

<Property name="LineComment">//</Property>
<Property name="BlockCommentStart">/*</Property>
<Property name="BlockCommentEnd">*/</Property>
<Property name="StringQuote">"</Property>
<Property name="StringQuote">'</Property>

The Rule Tag

The Rule tag needs to be placed inside the SyntaxMode tag. Each Rule tag defines an own set of delimiters, keywords, spans and matches that can be used for highlighting specific parts of the buffer. The different rules that ar being used to highlight different parts of the buffer are defined using the Span tag.

A Rule tag has following attributes:

Name Required Description
name yes  The name to identify this rule
color no  The default color of this rule, if it is not specified default color will be ‘text’
ignorecase no If true, the case of the keywords specified in this rule are ignored. If the tag is not specified the ignorecase from the syntax mode in which the rule is defined will be taken. Note that Keywords tags may be override this setting.

Example rule from C# mode:

<Rule name = "Comment">
    <Keywords color="comment.keyword.todo" ignorecase="True">

These rule is applied to comments. In the editor it looks like:


The Span Tag

A span is a part of the buffer that is highlighted differently using a begin and an end string. The begin and end strings are specfied as childs of the Span tag.

A Span tag can have following attributes:

Name Required Description
rule no The rule that is valid inside the span. If no rule is specified the current rule is taken. If no keywords should be highlighted point to an empty rule.
color no The default color of the span content (‘text’ is default color).
tagcolor no The color of the begin and end string (default is the span color).
escape no A string that is taken as escape inside the span. This escape string may contain the end string. For example \” is the escape string for C# strings.
stopateol no If true an end of line stops the span, otherwise it will be a multiple line span. The default is ‘false’.

Note that the order in which the spans are defined is important. When there is a span that starts with a prefix of an other span’s begin string it needs to be specified before the other span. Otherwise the other span would always be taken.

Example for C# block comments:

<Span color = "comment.block" rule="Comment" tagColor="comment.tag.block">

The comment block span in the editor is like: ss-blockSpan.png

Begin and End tags

The Begin and End tags can specify a ‘flag’ attribute that can give a bit more information about where the tags are valid.

  • startsLine: If true, the tag must be at column 1
  • firstNonWs: If true only whitespaces in the line where the tag are allowed before the tag.