Module:String: Difference between revisions

    m>Dragons flight
    (add description and whitespace handling option for len)
    m>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" );
    Retrieved from "https://nonbinary.wiki/wiki/Module:String"