File sniffers allow the framework to distinguish between different file types that use the same file extension. A file sniffer is expected to look at the actual file content to determine if the file is supported.

The file sniffer implementation should return a SniffInfo instance where the IsSupported is set to true if the file is of the expected type.

The file sniffer may also attempt to automatically detect the encoding and the source (and target) language of the file. When detecting such things, the file sniffer also specifies a confidence level for the detection, which allows applications to determine whether they may need to ask the user for additional information or not.

The file type manager invokes the Sniff(String, Language, Codepage, INativeTextLocationMessageReporter, ISettingsGroup) method on a file sniffer associated with a file type definition to determine if the file is of a type that can be processed.

The file sniffer implementation must be stateless and thread safe, since for performance reasons the file sniffer may be cached and re-used across multiple files, possibly also in a multi-threaded environment. The easiest way to accomplish this is by ensuring that the Sniff(String, Language, Codepage, INativeTextLocationMessageReporter, ISettingsGroup) implementation does not modify any class member fields and to avoid using static variables.

The file sniffer is also recommended (but not required) to implement IFileTypeDefinitionAware. If this interface is implemented, it will be used by the framework to communicate the file type definition used to instantiate the sniffer.

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