Module:String
Revision as of 18:56, 22 February 2013 by >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.)
Documentation for this module may be created at Module:String/doc
local str = {}
function str.len( frame )
return mw.ustring.len( frame.args.s )
end
function str.sub( frame )
return mw.ustring.sub( frame.args.s, tonumber( frame.args.i ), tonumber( frame.args.j ) )
end
function str.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
function str.match( frame )
return mw.ustring.match( frame.args.s, frame.args.pattern, tonumber( frame.args.i ) )
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
if type( plain ) == 'string' then
plain = plain:lower();
if plain == 'false' or plain == 'no' or plain == '0' then
plain = false;
else
plain = true;
end
end
local start = mw.ustring.find( source_str, pattern, start_pos, plain )
if start == nil then
start = 0
end
return start
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