Data.TCache.IndexText

Implements full text indexation (indexText) and text search(contains), as an addition to the query language implemented in IndexQuery it also can index the lists of elements in a field (with indexList) so that it is possible to ask for the registers that contains a given element in the given field (with containsElem)

An example of full text search i before and after an update in the text field

data Doc= Doc{title, body :: String} deriving (Read,Show, Typeable)
instance Indexable Doc where
  key Doc{title=t}= t

instance Serializable Doc  where
  serialize= pack . show
  deserialize= read . unpack

main= do
  indexText  body T.pack
  let doc= Doc{title=  title, body=  "hola que tal estamos"}
  rdoc <- atomically $ newDBRef doc
  r1 <- atomically $ select title $ body `'contains'\` "hola que tal"
  print r1

atomically $ writeDBRef rdoc  doc{ body=  que tal}
  r <- atomically $ select title $ body  `'contains'\` "hola que tal"
  print r
  if  r1 == [title doc] then print "OK" else print "FAIL"
  if  r== [] then print "OK" else print "FAIL"

Documentation

indexText

Arguments

:: (IResource a, Typeable a, Typeable b)

=> (a -> b)

field to index

-> (b -> Text)

method to convert the field content to lazy Text (for example pack in case of String fields). This permits to index non Textual fields

-> IO ()

start a trigger to index the contents of a register field

indexList

Arguments

:: (IResource a, Typeable a, Typeable b)

=> (a -> b)

field to index

-> (b -> [Text])

method to convert a field element to Text (for example `pack . show` in case of elemets with Show instances)

-> IO ()

trigger the indexation of list fields with elements convertible to Text

contains

Arguments

:: (IResource a, Typeable a, Typeable b)

=> (a -> b)

field to search in

-> String

text to search

-> STM [DBRef a]

return the DBRefs whose fields include all the words of length three or more in the requested text contents

containsElem :: (IResource a, Typeable a, Typeable b) => (a -> b) -> String -> STM [DBRef a]

return the DBRefs of the registers whose field (first parameter, usually a container) contains the requested value.