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podoc:tokenized_like_sql_function

Database Function Description of "tokenized_like"

Name

tokenized_like

Description

This function searches for exact matches of 'keyword' in 'string'.

The input 'string' is tokenized by a space, and each token is comapred to the 'keyword'. True is returned if the token fully matches the keyword. If the 'keyword' did not match any of the tokens of 'string' false is returned.

This function is case sensitive.

There is an alternative second version that has an integer as first argument.

Purpose

Searching for keywords.

Schema

-- This function searches for exact matches of 'keyword' in 'string'.
-- The input 'string' is tokenized by a space, and each token is comapred
-- to the 'keyword'. True is returned if the token fully matches the
-- keyword. If the 'keyword' did not match any of the tokens of 'string'
-- false is returned.
-- This function is case sensitive.
 
CREATE FUNCTION tokenized_like(VARCHAR, VARCHAR) RETURNS bool AS '
declare
  string alias for $1;
  keyword alias for $2;
 
  token varchar;
  character char;
  string_length integer;
  token_length integer;
  token_begin integer;
  index_cursor integer;
  head_cursor integer;
begin
  head_cursor := 1;
  string_length := char_length(string);
 
  while head_cursor < string_length loop
    token_length := 0;
    index_cursor := head_cursor;
    token_begin := head_cursor;
    character := substring(string from index_cursor for 1);
    while index_cursor <= string_length loop
      if ((character = \' \') or (character = \';\') or (index_cursor = string_length)) then
        if (index_cursor = string_length) then
          token_length := token_length + 1;
        end if;
        token := substring(string from token_begin for token_length);
        if (token = keyword) then
          return true;
        end if;
      end if;
      token_length := token_length + 1;
      index_cursor := index_cursor + 1;
      character := substring(string from index_cursor for 1);
    end loop;
 
    index_cursor := head_cursor;
    while index_cursor <= string_length loop
      character := substring(string from index_cursor for 1);
      if ((character = \' \') or (character = \';\') or (index_cursor = string_length)) then
        head_cursor := index_cursor + 1;
        exit;
      end if;
      index_cursor := index_cursor + 1;
    end loop;
  end loop;
 
  return false;
end;
' LANGUAGE 'plpgsql';
-- we define operators for each of our functions so that we can easily integrate
-- them into the current PO search queries
CREATE operator ==== (
  leftarg = VARCHAR,
  rightarg = VARCHAR,
  PROCEDURE = tokenized_like,
  commutator = ====
);
-- This function is exactly like tokenized_like, but its first argument is integer
CREATE FUNCTION tokenized_like(INTEGER, VARCHAR) RETURNS bool AS '
declare
  identifier alias for $1;
  keyword alias for $2;
begin
  return tokenized_like(text(identifier), keyword);
end;
' LANGUAGE 'plpgsql';
-- we define operators for each of our functions so that we can easily integrate
-- them into the current PO search queries
CREATE operator ==== (
  leftarg = INTEGER,
  rightarg = VARCHAR,
  PROCEDURE = tokenized_like,
  commutator = ====
);

History

Used first

Version 2.30

Used last

Still in use

Change history

= Version 2.30 =

-- This function searches for exact matches of 'keyword' in 'string'.
-- The input 'string' is tokenized by a space, and each token is comapred
-- to the 'keyword'. True is returned if the token fully matches the
-- keyword. If the 'keyword' did not match any of the tokens of 'string'
-- false is returned.
-- This function is case sensitive.
 
CREATE FUNCTION tokenized_like(VARCHAR, VARCHAR) RETURNS bool AS '
declare
  string alias for $1;
  keyword alias for $2;
 
  token varchar;
  character char;
  string_length integer;
  token_length integer;
  token_begin integer;
  index_cursor integer;
  head_cursor integer;
begin
  head_cursor := 1;
  string_length := char_length(string);
 
  while head_cursor < string_length loop
    token_length := 0;
    index_cursor := head_cursor;
    token_begin := head_cursor;
    character := substring(string from index_cursor for 1);
    while index_cursor <= string_length loop
      if ((character = \' \') or (character = \';\') or (index_cursor = string_length)) then
        if (index_cursor = string_length) then
          token_length := token_length + 1;
        end if;
        token := substring(string from token_begin for token_length);
        if (token = keyword) then
          return true;
        end if;
      end if;
      token_length := token_length + 1;
      index_cursor := index_cursor + 1;
      character := substring(string from index_cursor for 1);
    end loop;
 
    index_cursor := head_cursor;
    while index_cursor <= string_length loop
      character := substring(string from index_cursor for 1);
      if ((character = \' \') or (character = \';\') or (index_cursor = string_length)) then
        head_cursor := index_cursor + 1;
        exit;
      end if;
      index_cursor := index_cursor + 1;
    end loop;
  end loop;
 
  return false;
end;
' LANGUAGE 'plpgsql';
-- we define operators for each of our functions so that we can easily integrate
-- them into the curret PO search queries
CREATE operator ==== (
  leftarg = VARCHAR,
  rightarg = VARCHAR,
  PROCEDURE = tokenized_like,
  commutator = ====
);
-- This function is exactly like tokenized_like, but its first argument is integer
CREATE FUNCTION tokenized_like(INTEGER, VARCHAR) RETURNS bool AS '
declare
  identifier alias for $1;
  keyword alias for $2;
begin
  return tokenized_like(text(identifier), keyword);
end;
' LANGUAGE 'plpgsql';
-- we define operators for each of our functions so that we can easily integrate
-- them into the curret PO search queries
CREATE operator ==== (
  leftarg = INTEGER,
  rightarg = VARCHAR,
  PROCEDURE = tokenized_like,
  commutator = ====
);
podoc/tokenized_like_sql_function.txt · Last modified: 2007/04/23 10:33 by Luud