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Module:String: Difference between revisions

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Module:String (view source)

Revision as of 02:06, 25 February 2013

2,745 bytes added ,  25 February 2013
improves commenting, adds whitespace and error handling to sub, improvements to error handling generally.
en>Dragons flight
(add description and whitespace handling option for len)
en>Dragons flight
(improves commenting, adds whitespace and error handling to sub, improvements to error handling generally.)
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--[[ 
This module is intended to provide access to basic string functions.
Most of the functions provided here can be invoked with named parameters,
unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will
automatically remove any leading or trailing whitespace from the parameter. 
Depending on the intended use, it may be advantageous to either preserve or
remove such whitespace.
Global options
    ignore_errors: If set to 'true' or 1, any error condition will result in
        an empty string being returned rather than an error message. 
       
    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].  If set to an empty
        string, no category will be added during an error.   
]]
local str = {}
local str = {}


--[====[
--[[
len
len


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{{#invoke:String|len|target_string|}}
{{#invoke:String|len|target_string|}}
OR
OR
{{#invoke:String|pos|s=target_string}}
{{#invoke:String|len|s=target_string}}


Parameters
Parameters
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If invoked using named parameters, Mediawiki will automatically remove any leading or
If invoked using named parameters, Mediawiki will automatically remove any leading or
trailing whitespace from the target string.   
trailing whitespace from the target string.   
]====]
]]
function str.len( frame )
function str.len( frame )
     local new_args = str._getParameters( frame.args, {'s'} );
     local new_args = str._getParameters( frame.args, {'s'} );
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end
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 )
function str.sub( frame )
     return mw.ustring.sub( frame.args.s, tonumber( frame.args.i ), tonumber( frame.args.j ) )
     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 j < i then
        return str._error( 'String subset indices out of order' );
    end
   
    if i > len or j > len or i < 1 or j < 1 then
        return str._error( 'String subset index out of range' );
    end
   
    return mw.ustring.sub( s, i, j )
end
end


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end
end


--[====[
--[[
pos
pos


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A requested value of zero, or a value greater than the length of the string returns an error.
A requested value of zero, or a value greater than the length of the string returns an error.
]====]
]]
function str.pos( frame )
function str.pos( frame )
     local new_args = str._getParameters( frame.args, {'target', 'pos'} );
     local new_args = str._getParameters( frame.args, {'target', 'pos'} );
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     if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) then
     if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) then
         return '<strong class="error">String index out of range</strong>';
         return str._error( 'String index out of range' );
     end     
     end     
      
      
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end
end


--[====[
--[[
str_find
str_find


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value of "1", which is generally unexpected behavior, and must be accounted for
value of "1", which is generally unexpected behavior, and must be accounted for
separatetly.
separatetly.
]====]
]]
function str.str_find( frame )
function str.str_find( frame )
     local new_args = str._getParameters( frame.args, {'source', 'target'} );
     local new_args = str._getParameters( frame.args, {'source', 'target'} );
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end
end


--[====[
--[[
find
find


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This function should be safe for UTF-8 strings.
This function should be safe for UTF-8 strings.
]====]
]]
function str.find( frame )
function str.find( frame )
     local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } );  
     local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } );  
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end
end


--[====[
--[[
replace
replace


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     plain: Boolean flag indicating that pattern should be understood as plain
     plain: Boolean flag indicating that pattern 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  
]====]
]]
function str.replace( frame )
function str.replace( frame )
     local new_args = str._getParameters( frame.args, {'source', 'pattern', 'replace', 'count', 'plain' } );  
     local new_args = str._getParameters( frame.args, {'source', 'pattern', 'replace', 'count', 'plain' } );  
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end
end


--[====[
--[[
Helper function that populates the argument list given that user may need to use a mix of
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
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
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.
we sometimes want to either preserve or remove that whitespace depending on the application.
]====]
]]
function str._getParameters( frame_args, arg_list )
function str._getParameters( frame_args, arg_list )
     local new_args = {};
     local new_args = {};
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end         
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;
   
    if str._getBoolean(ignore_errors) then
        return '';
    end
   
    local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>';
    if error_category ~= '' then
        error_str = '[[Category:' .. error_category .. ']]' .. error_str;
    end       
   
    return error_str;
end
 
--[[
Helper Function to interpret boolean strings
Helper Function to interpret boolean strings
]====]
]]
function str._getBoolean( boolean_str )
function str._getBoolean( boolean_str )
     local boolean_value;
     local boolean_value;
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end
end


--[====[
--[[
Helper function that escapes all pattern characters so that they will be treated  
Helper function that escapes all pattern characters so that they will be treated  
as plain text.
as plain text.
]====]
]]
function str._escapePattern( pattern_str )
function str._escapePattern( pattern_str )
     return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" );
     return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" );
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