Create Custom Language (Syntax Parsing Engine)

This topic explains the process of creating a custom language.

The following topics are prerequisites to understanding this topic:

This topic contains the following sections:

Once a grammar definition is complete you can use it to parse documents which must conform to that grammatical structure. Here are the steps for doing this:

There are two ways to create a custom language from a grammar:

You can create a custom language for a grammar by passing the Grammar instance to the constructor of the CustomLanguage class, which is derived from LanguageBase. This will create a CustomLanguage instance specifically built to parse documents based on the provided Grammar instance.

The following table contains the members that are publicly exposed on the CustomLanguage class:

You can create a custom language from a grammar by generating a LanguageBase-derived class specifically built to parse documents with a specific grammar definition. Creating a CustomLanguage can be thought of as dynamic creation of a language whereas generating a language class can be thought of as pre-compiling a language. Building the lexical and syntax analyzers can be slow for complex grammars. If the CustomLanguage approach is used, that building phase needs to happen the first time a document is parsed for each run of the application. This may be acceptable for simple languages or when debugging a grammar definition on a developer’s machine, but for a complex language being used on a user’s machine, it may not be. By using the language generation approach, the lexical and syntax analyzers are built once on the developer’s machine. Then information about how to reconstruct the analyzers and Grammar is written out to a generated class file. Each class file generated derives from LanguageBase, has a static property named Instance returning a singleton instance of itself, and a public constructor in case two copies of the language need to be created with different services in their ServicesManager. In addition, the generated class has a Grammar property which returns an identical copy of the Grammar used to generate the language.

One of the options for generating the language class is to give it the “partial” modifier. This allows you to create another file for the derived language so you can override certain members on LanguageBase or add your own. The members that can be overridden on LanguageBase are as follows

You can generate a language by using the LanguageGenerator class in the Infragistics.Documents.Parsing namespace. This class has the following static methods:

The LanguageGenerationParams class used as argument in the GenerateClass methods has several options to customize the language generation process. They are as follows: