KFileMetaData provides a simple library for extracting the text and metadata from a number of different files. This library is typically used by file indexers to retreive the metadata.
In order to use the library you must implement your own ExtractionResult
class. Instances of this class will be passed to every applicable plugin and
they will populate with the information.
For convenience a SimpleResult class has been provided which stores all the
data in memory and allows it to be introspected later. Most clients should
implement thier own ExtractionResult as the data can get quite large when
extracting the text content from very large files.
This requires us to create a ExtractionPluginManger class, fetch the extractor
plugins which are applicable for that file, and then pass the instance of
ExtractionResult to each Extractor.
A simple test example called dump.cpp has been written.
The Metadata is extracted with the help of Extraction Plugins. Each plugin
provides a list of mimetypes that it supports, and implements the extraction
function which extracts the data and fills it in an ExtractionResult.
Most of the common file types are already provided by the library.
Extractors should typically avoid implementing any logic themselves and should just be wrappers on top of existing libraries.
The ExtractionResult can be filled with (key, value) pairs and plain text. The
keys in these pairs typically correspond to a predefinied property. The list
of properties is defined in the properties.h header. Every plugin should
use the properties defined in this header. If a required property is missing
then it should be added to this framework.
The ExtractionResult should also be given a list of types. These types are
defined in the types.h header. The correspond to a higher level overview
of the files which the user typically expects.
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