Module:String: Difference between revisions

    From Nonbinary Wiki
    (as copied directly from en:Module:String)
    (Reverting until it can be figured out why this update broke Template:Strlen and Template:git)
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    --[[ 
    local p = {}


    This module is intended to provide access to basic string functions.
    function p.length( frame )
        local arg1 = frame.args[1]
        return string.len( arg1 )
    end   


    Most of the functions provided here can be invoked with named parameters,
    function p.sub( frame )
    unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will
         local arg1 = frame.args[1]
    automatically remove any leading or trailing whitespace from the parameter. 
         local arg2 = tonumber( frame.args[2] )
    Depending on the intended use, it may be advantageous to either preserve or
         local arg3 = tonumber( frame.args[3] )
    remove such whitespace.
         if arg2 and arg3 then
     
             local first = arg2 + 1
    Global options
             local last  = arg2 + arg3
        ignore_errors: If set to 'true' or 1, any error condition will result in
             return string.sub( arg1, first, last )
            an empty string being returned rather than an error message. 
         else
           
             return ""
        error_category: If an error occurs, specifies the name of a category to
            include with the error message.  The default category is 
            [Category:Errors reported by Module String].
           
        no_category: If set to 'true' or 1, no category will be added if an error
            is generated.
           
    Unit tests for this module are available at Module:String/tests.
    ]]
     
    local str = {}
     
    --[[
    len
     
    This function returns the length of the target string.
     
    Usage:
    {{#invoke:String|len|target_string|}}
    OR
    {{#invoke:String|len|s=target_string}}
     
    Parameters
        s: The string whose length to report
     
    If invoked using named parameters, Mediawiki will automatically remove any leading or
    trailing whitespace from the target string. 
    ]]
    function str.len( frame )
         local new_args = str._getParameters( frame.args, {'s'} );
        local s = new_args['s'] or '';
        return mw.ustring.len( s )
    end
     
    --[[
    sub
     
    This function returns a substring of the target string at specified indices.
     
    Usage:
    {{#invoke:String|sub|target_string|start_index|end_index}}
    OR
    {{#invoke:String|sub|s=target_string|i=start_index|j=end_index}}
     
    Parameters
        s: The string to return a subset of
        i: The fist index of the substring to return, defaults to 1.
        j: The last index of the string to return, defaults to the last character.
       
    The first character of the string is assigned an index of 1.  If either i or j
    is a negative value, it is interpreted the same as selecting a character by
    counting from the end of the string.  Hence, a value of -1 is the same as
    selecting the last character of the string.
     
    If the requested indices are out of range for the given string, an error is
    reported.
    ]]
    function str.sub( frame )
         local new_args = str._getParameters( frame.args, { 's', 'i', 'j' } );
        local s = new_args['s'] or '';
        local i = tonumber( new_args['i'] ) or 1;
         local j = tonumber( new_args['j'] ) or -1;
       
        local len = mw.ustring.len( s );
     
        -- Convert negatives for range checking
         if i < 0 then
             i = len + i + 1;
        end
        if j < 0 then
             j = len + j + 1;
        end
       
        if i > len or j > len or i < 1 or j < 1 then
             return str._error( 'String subset index out of range' );
        end
         if j < i then
             return str._error( 'String subset indices out of order' );
         end
         end
       
    end
        return mw.ustring.sub( s, i, j )
    end


    --[[
    --[[
    Line 100: Line 23:
    to maintain these older templates.
    to maintain these older templates.
    ]]
    ]]
    function str.sublength( frame )
    function p.sublength( frame )
         local i = tonumber( frame.args.i ) or 0
         local i = tonumber( frame.args.i ) or 0
         local len = tonumber( frame.args.len )
         local len = tonumber( frame.args.len )
    Line 106: Line 29:
    end
    end


    --[[
    return p
    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|nomatch_output}}
    OR
    {{#invoke:String|pos|s=source_string|pattern=pattern_string|start=start_index
        |match=match_number|plain=plain_flag|nomatch=nomatch_output}}
     
    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: A flag indicating that the pattern should be understood as plain
            text.  Defaults to false.
        nomatch: If no match is found, output the "nomatch" value rather than an error.
     
    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 )
        local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain', 'nomatch'} );
        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 );
        local nomatch = new_args['nomatch'];
       
        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
            if nomatch == nil then
                return str._error( 'Match not found' );
            else
                return nomatch;
            end
        else
            return result;
        end
    end
     
    --[[
    pos
     
    This function returns a single character from the target string at position pos.
     
    Usage:
    {{#invoke:String|pos|target_string|index_value}}
    OR
    {{#invoke:String|pos|target=target_string|pos=index_value}}
     
    Parameters
        target: The string to search
        pos: The index for the character to return
     
    If invoked using named parameters, Mediawiki will automatically remove any leading or
    trailing whitespace from the target string.  In some circumstances this is desirable, in
    other cases one may want to preserve the whitespace.
     
    The first character has an index value of 1.
     
    If one requests a negative value, this function will select a character by counting backwards
    from the end of the string.  In other words pos = -1 is the same as asking for the last character.
     
    A requested value of zero, or a value greater than the length of the string returns an error.
    ]]
    function str.pos( frame )
        local new_args = str._getParameters( frame.args, {'target', 'pos'} );
        local target_str = new_args['target'] or '';
        local pos = tonumber( new_args['pos'] ) or 0;
     
        if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) then
            return str._error( 'String index out of range' );
        end   
       
        return mw.ustring.sub( target_str, pos, pos );
    end
     
    --[[
    str_find
     
    This function duplicates the behavior of {{str_find}}, including all of its quirks.
    This is provided in order to support existing templates, but is NOT RECOMMENDED for
    new code and templates.  New code is recommended to use the "find" function instead.
     
    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".
     
    Important Note: If the "target" string is empty / missing, this function returns a
    value of "1", which is generally unexpected behavior, and must be accounted for
    separatetly.
    ]]
    function str.str_find( frame )
        local new_args = str._getParameters( frame.args, {'source', 'target'} );
        local source_str = new_args['source'] or '';
        local target_str = new_args['target'] or '';
     
        if target_str == '' then
            return 1;
        end   
       
        local start = mw.ustring.find( source_str, target_str, 1, true )
        if start == nil then
            start = -1
        end
       
        return start
    end
     
    --[[
    find
     
    This function allows one to search for a target string or pattern within another
    string.
     
    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
        target: The string or pattern to find within source
        start: The index within the source string to start the search, defaults to 1
        plain: Boolean flag indicating that target should be understood as plain
            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
    within "source".  Indices are 1-based.  If "target" is not found, then this
    function returns 0.  If either "source" or "target" are missing / empty, this
    function also returns 0.
     
    This function should be safe for UTF-8 strings.
    ]]
    function str.find( frame )
        local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } );
        local source_str = new_args['source'] or '';
        local pattern = new_args['target'] or '';
        local start_pos = tonumber(new_args['start']) or 1;
        local plain = new_args['plain'] or true;
           
        if source_str == '' or pattern == '' then
            return 0;
        end   
       
        plain = str._getBoolean( plain );
     
        local start = mw.ustring.find( source_str, pattern, start_pos, plain )
        if start == nil then
            start = 0
        end
       
        return start
    end
     
    --[[
    replace
     
    This function allows one to replace a target string or pattern within another
    string.
     
    Usage:
    {{#invoke:String|replace|source_str|pattern_string|replace_string|replacement_count|plain_flag}}
    OR
    {{#invoke:String|replace|source=source_string|pattern=pattern_string|replace=replace_string|
      count=replacement_count|plain=plain_flag}}
     
    Parameters
        source: The string to search
        pattern: The string or pattern to find within source
        replace: The replacement text
        count: The number of occurences to replace, defaults to all.
        plain: Boolean flag indicating that pattern should be understood as plain
            text and not as a Lua style regular expression, defaults to true
    ]]
    function str.replace( frame )
        local new_args = str._getParameters( frame.args, {'source', 'pattern', 'replace', 'count', 'plain' } );
        local source_str = new_args['source'] or '';
        local pattern = new_args['pattern'] or '';
        local replace = new_args['replace'] or '';
        local count = tonumber( new_args['count'] );
        local plain = new_args['plain'] or true;
           
        if source_str == '' or pattern == '' then
            return source_str;
        end   
        plain = str._getBoolean( plain );
     
        if plain then
            pattern = str._escapePattern( pattern );
            replace = mw.ustring.gsub( replace, "%%", "%%%%" ); --Only need to escape replacement sequences.
        end
       
        local result;
     
        if count ~= nil then
            result = mw.ustring.gsub( source_str, pattern, replace, count );
        else
            result = mw.ustring.gsub( source_str, pattern, replace );
        end       
     
        return result;
    end
     
    --[[
        simple function to pipe string.rep to templates.
    ]]
     
    function str.rep( frame )
        local repetitions = tonumber( frame.args[2] )
        if not repetitions then
            return str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args[2] or '' ) .. '"' )
        end
        return string.rep( frame.args[1] or '', repetitions )
    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       
     
    --[[
    Helper function to handle error messages.
    ]]
    function str._error( error_str )
        local frame = mw.getCurrentFrame();
        local error_category = frame.args.error_category or 'Errors reported by Module String';
        local ignore_errors = frame.args.ignore_errors or false;
        local no_category = frame.args.no_category or false;
       
        if str._getBoolean(ignore_errors) then
            return '';
        end
       
        local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>';
        if error_category ~= '' and not str._getBoolean( no_category ) then
            error_str = '[[Category:' .. error_category .. ']]' .. error_str;
        end       
       
        return error_str;
    end
     
    --[[
    Helper Function to interpret boolean strings
    ]]
    function str._getBoolean( boolean_str )
        local boolean_value;
       
        if type( boolean_str ) == 'string' then
            boolean_str = boolean_str:lower();
            if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'
                    or boolean_str == '' then
                boolean_value = false;
            else
                boolean_value = true;
            end   
        elseif type( boolean_str ) == 'boolean' then
            boolean_value = boolean_str;
        else
            error( 'No boolean value found' );
        end   
        return boolean_value
    end
     
    --[[
    Helper function that escapes all pattern characters so that they will be treated
    as plain text.
    ]]
    function str._escapePattern( pattern_str )
        return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" );
    end
     
    return str

    Revision as of 14:15, 7 February 2014

    Documentation for this module may be created at Module:String/doc 

    local p = {}

function p.length( frame )
    local arg1 = frame.args[1]
    return string.len( arg1 )
end    

function p.sub( frame )
    local arg1 = frame.args[1]
    local arg2 = tonumber( frame.args[2] )
    local arg3 = tonumber( frame.args[3] )
    if arg2 and arg3 then
        local first = arg2 + 1
        local last  = arg2 + arg3
        return string.sub( arg1, first, last )
    else
        return ""
    end
end  

--[[
This function implements that features of {{str sub old}} and is kept in order
to maintain these older templates.
]]
function p.sublength( frame )
    local i = tonumber( frame.args.i ) or 0
    local len = tonumber( frame.args.len )
    return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )
end

return p
    Retrieved from "https://nonbinary.wiki/index.php?title=Module:String&oldid=20651"