Module:String: Difference between revisions

    m>Dragons flight
    (add support for finding the position of a string or pattern inside another string.)
    m>Dragons flight
    (Update to allow for unnamed parameters. This is necessary because some string function need to preserve leading / trailing whitespace in order to work properly.)
    Line 27: Line 27:


    Returns the first index in "source" that is a match to "target".  Indexing is 1-based,
    Returns the first index in "source" that is a match to "target".  Indexing is 1-based,
    and the function returns -1 if the "target" string is not present in "source".  Both
    and the function returns -1 if the "target" string is not present in "source".
    strings have any leading or trailing whitespace removed before searching.


    Important Note: If the "target" string is empty / missing, this function returns a
    Important Note: If the "target" string is empty / missing, this function returns a
    Line 35: Line 34:
    ]====]
    ]====]
    function str.str_find( frame )
    function str.str_find( frame )
         local source_str = frame.args.source or '';
         local new_args = str._getParameters( frame.args, {'source', 'target'} );
         local target_str = frame.args.target or '';
        local source_str = new_args['source'] or '';
        if target_str == '' then
         local target_str = new_args['target'] or '';
     
    if target_str == '' then
             return 1;
             return 1;
         end     
         end     
    Line 55: Line 56:
    string.
    string.


    Parameters:
    Usage:
    {{#invoke:String|find|source_str|target_string|start_index|plain_flag}}
    OR
    {{#invoke:String|find|source=source_str|target=target_str|start=start_index|plain=plain_flag}}
     
    Parameters
         source: The string to search
         source: The string to search
         target: The string or pattern to find within source
         target: The string or pattern to find within source
    Line 61: Line 67:
         plain: Boolean flag indicating that target should be understood as plain
         plain: Boolean flag indicating that target should be understood as plain
             text and not as a Lua style regular expression, defaults to true
             text and not as a Lua style regular expression, defaults to true
           
     
    If invoked using named parameters, Mediawiki will automatically remove any leading or
    trailing whitespace from the parameter.  In some circumstances this is desirable, in
    other cases one may want to preserve the whitespace.
     
    This function returns the first index >= "start" where "target" can be found  
    This function returns the first index >= "start" where "target" can be found  
    within "source".  Indices are 1-based.  If "target" is not found, then this  
    within "source".  Indices are 1-based.  If "target" is not found, then this  
    Line 67: Line 77:
    function also returns 0.
    function also returns 0.


    Both "source" and "target" will be trimmed so that any leading or trailing
    This function should be safe for UTF-8 strings.
    whitespace is removed prior to searching.  This function should be safe for
    UTF-8 strings.
    ]====]
    ]====]
    function str.find( frame )
    function str.find( frame )
         local source_str = frame.args.source or '';
         local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } );
         local pattern = frame.args.target or '';
        local source_str = new_args['source'] or '';
         local start_pos = tonumber(frame.args.start) or 1;
         local pattern = new_args['target'] or '';
         local plain = frame.args.plain or true;
         local start_pos = tonumber(new_args['start']) or 1;
         local plain = new_args['plain'] or true;
              
              
         if source_str == '' or pattern == '' then
         if source_str == '' or pattern == '' then
    Line 97: Line 106:
         return start
         return start
    end
    end
    --[====[
    Helper function that populates the argument list given that user may need to use a mix of
    named and unnamed parameters.  This is relevant because named parameters are not
    identical to unnamed parameters due to string trimming, and when dealing with strings
    we sometimes want to either preserve or remove that whitespace depending on the application.
    ]====]
    function str._getParameters( frame_args, arg_list )
        local new_args = {};
        local index = 1;
        local value;
       
        for i,arg in ipairs( arg_list ) do
            value = frame_args[arg]
            if value == nil then
                value = frame_args[index];
                index = index + 1;
            end
            new_args[arg] = value;
        end
       
        return new_args;
    end       
    return str
    return str
    Retrieved from "https://nonbinary.wiki/wiki/Module:String"