Module:String: Difference between revisions

    m>Dragons flight
    (fix pattern escape in replace function)
    m>Dragons flight
    (adds updated match support with wider parameter choices, whitespace handling, etc.)
    Line 96: Line 96:
    end
    end


    --[[
    This function implements that features of {{str sub old}} and is kept in order
    to maintain these older templates.
    ]]
    function str.sublength( frame )
    function str.sublength( frame )
         local i = tonumber( frame.args.i ) or 0
         local i = tonumber( frame.args.i ) or 0
    Line 102: Line 106:
    end
    end


    --[[
    match
    This function returns a substring from the source string that matches a
    specified pattern.
    Usage:
    {{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag}}
    OR
    {{#invoke:String|pos|s=source_string|pattern=pattern_string|start=start_index
        |match=match_number|plain=plain_flag}}
    Parameters
        s: The string to search
        pattern: The pattern or string to find within the string
        start: The index within the source string to start the search.  The first
            character of the string has index 1.  Defaults to 1.
        match: In some cases it may be possible to make multiple matches on a single
            string.  This specifies which match to return, where the first match is
            match= 1.  If a negative number is specified then a match is returned
            counting from the last match.  Hence match = -1 is the same as requesting
            the last match.  Defaults to 1.
        plain_flag: A flag indicating that the pattern should be understood as plain
            text.  Defaults to false.
    If invoked using named parameters, Mediawiki will automatically remove any leading or
    trailing whitespace from each string.  In some circumstances this is desirable, in
    other cases one may want to preserve the whitespace.
    If the match_number or start_index are out of range for the string being queried, then
    this function generates an error.  An error is also generated if no match is found.
    If one adds the parameter ignore_errors=true, then the error will be suppressed and
    an empty string will be returned on any failure.
    For information on constructing Lua patterns, a form of [regular expression], see:
    * http://www.lua.org/manual/5.1/manual.html#5.4.1
    * http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
    * http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns
    ]]
    function str.match( frame )
    function str.match( frame )
         return mw.ustring.match( frame.args.s, frame.args.pattern, tonumber( frame.args.i ) )
         local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain'} );
        local s = new_args['s'] or '';
        local start = tonumber( new_args['start'] ) or 1;
        local plain_flag = str._getBoolean( new_args['plain'] or false );
        local pattern = new_args['pattern'] or '';
        local match_index = math.floor( tonumber(new_args['match']) or 1 );
       
        if s == '' then
            return str._error( 'Target string is empty' );
        end
        if pattern == '' then
            return str._error( 'Pattern string is empty' );
        end
        if math.abs(start) < 1 or math.abs(start) > mw.ustring.len( s ) then
            return str._error( 'Requested start is out of range' );
        end
        if match_index == 0 then
            return str._error( 'Match index is out of range' );
        end
        if plain_flag then
            pattern = str._escapePattern( pattern );
        end
       
        local result
        if match_index == 1 then
            -- Find first match is simple case
            result = mw.ustring.match( s, pattern, start )
        else
            if start > 1 then
                s = mw.ustring.sub( s, start );
            end
           
            local iterator = mw.ustring.gmatch(s, pattern);
            if match_index > 0 then
                -- Forward search
                for w in iterator do
                    match_index = match_index - 1;
                    if match_index == 0 then
                        result = w;
                        break;
                    end
                end   
            else
                -- Reverse search
                local result_table = {};
                local count = 1;
                for w in iterator do
                    result_table[count] = w;
                    count = count + 1;
                end
               
                result = result_table[ count + match_index ];           
            end
        end       
       
        if result == nil then
            return str._error( 'Match not found' );
        else
            return result;
        end
    end
    end


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