Package org.teiid.translator.jdbc

Class LocateFunctionModifier

  • Direct Known Subclasses:
    LocateFunctionModifier
    public class LocateFunctionModifier
extends AliasModifier
    A modifier class that can be used to translate the scalar function locate(search_string, source_string) and locate(search_string, source_string, start_index) to a function or expression that can be used at the data source.

    If the default implementation is used, a function name of LOCATE will be used for the function name.

    If the default implementation is used, the expression will not be modified if:

    • locate(search_string, source_string) is used
    • locate(search_string, source_string, start_index) is used and start_index is a literal integer greater then 0
    • the default function parameter order is used or unspecified

    If the default implementation is used, the expression will be modified if:

    • locate(search_string, source_string, start_index) is used and start_index is a literal integer less then 1
    • locate(search_string, source_string, start_index) is used and start_index is not a literal integer
    • the function parameter order is something other than the default

    If the default implementation is used and the expression is modified, it is modified to ensure that any literal integer value less than 1 is made equal to 1 and any non literal value is wrapped by a searched case expression to ensure that a value of less then 1 will be equal to 1 and the parameter order matches that of what the data source expects.

    For example:

    • locate('a', 'abcdef') --> LOCATE('a', 'abcdef')
    • locate('a', 'abcdef', 2) --> LOCATE('a', 'abcdef', 2)
    • locate('a', 'abcdef', 0) --> LOCATE('a', 'abcdef', 1)
    • locate('a', 'abcdef', intCol) --> LOCATE('a', 'abcdef', CASE WHEN intCol < 1 THEN 1 ELSE intCol END)
    Since:
    6.2

    • Field Detail

      • LOCATE

        public static String LOCATE

    • Constructor Detail

      • LocateFunctionModifier

        public LocateFunctionModifier​(LanguageFactory langFactory)
        Translates the scalar function LOCATE() to a source specific scalar function or expression.
        Parameters:
        langFactory - the language factory associated with translation

      • LocateFunctionModifier

        public LocateFunctionModifier​(LanguageFactory langFactory,
                              String functionName,
                              boolean sourceStringFirst)
        Translates the scalar function LOCATE() to a source specific scalar function or expression.
        Parameters:
        langFactory - the language factory associated with translation
        functionName - the function name or alias to be used instead of LOCATE
        sourceStringFirst -

    • Method Detail

      • modify

        public void modify​(Function function)
        Returns a version of function suitable for executing at the data source.

        For example: locate('a', 'abcdefg') ---> LOCATE('a', 'abcdefg')
        locate('a', 'abcdefg', 1) ---> LOCATE('a', 'abcdefg', 1)
        locate('a', 'abcdefg', 1) ---> INSTR('abcdefg', 'a', 1)
        locate('a', 'abcdefg', -5) ---> INSTR('abcdefg', 'a', 1)
        locate('a', 'abcdefg', 1) ---> FINDSTR('a', 'abcdefg', 1)
        locate('a', 'abcdefg', myCol) ---> LOCATE('a', 'abcdefg', CASE WHEN myCol < 1 THEN 1 ELSE myCol END)

        Overrides:
        modify in class AliasModifier
        Parameters:
        function - the LOCATE function that may need to be modified

      • getLanguageFactory

        protected LanguageFactory getLanguageFactory()
        Get the instance of LanguageFactory set during construction.
        Returns:
        the ILanguageFactory instance