Module:String: Difference between revisions

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    --[[
    --[[


    This module is intended to provide access to basic string functions.
    This module is intended to provide access to basic string functions.


    Most of the functions provided here can be invoked with named parameters,  
    Most of the functions provided here can be invoked with named parameters,
    unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will  
    unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will
    automatically remove any leading or trailing whitespace from the parameter.
    automatically remove any leading or trailing whitespace from the parameter.
    Depending on the intended use, it may be advantageous to either preserve or
    Depending on the intended use, it may be advantageous to either preserve or
    remove such whitespace.
    remove such whitespace.


    Global options
    Global options
         ignore_errors: If set to 'true' or 1, any error condition will result in  
         ignore_errors: If set to 'true' or 1, any error condition will result in
             an empty string being returned rather than an error message.
             an empty string being returned rather than an error message.
           
     
         error_category: If an error occurs, specifies the name of a category to  
         error_category: If an error occurs, specifies the name of a category to
             include with the error message.  The default category is
             include with the error message.  The default category is
             [Category:Errors reported by Module String].
             [Category:Errors reported by Module String].
           
     
         no_category: If set to 'true' or 1, no category will be added if an error
         no_category: If set to 'true' or 1, no category will be added if an error
             is generated.
             is generated.
           
     
    Unit tests for this module are available at Module:String/tests.
    Unit tests for this module are available at Module:String/tests.
    ]]
    ]]
    Line 39: Line 39:


    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'} )
        local s = new_args['s'] or '';
    local s = new_args['s'] or ''
        return mw.ustring.len( s )
    return mw.ustring.len( s )
    end
    end


    Line 61: Line 61:
         i: The fist index of the substring to return, defaults to 1.
         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.
         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
    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  
    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  
    counting from the end of the string.  Hence, a value of -1 is the same as
    selecting the last character of the string.
    selecting the last character of the string.


    If the requested indices are out of range for the given string, an error is  
    If the requested indices are out of range for the given string, an error is
    reported.
    reported.
    ]]
    ]]
    function str.sub( frame )
    function str.sub( frame )
        local new_args = str._getParameters( frame.args, { 's', 'i', 'j' } );
    local new_args = str._getParameters( frame.args, { 's', 'i', 'j' } )
        local s = new_args['s'] or '';
    local s = new_args['s'] or ''
        local i = tonumber( new_args['i'] ) or 1;
    local i = tonumber( new_args['i'] ) or 1
        local j = tonumber( new_args['j'] ) or -1;
    local j = tonumber( new_args['j'] ) or -1
       
     
        local len = mw.ustring.len( s );
    local len = mw.ustring.len( s )


        -- Convert negatives for range checking
    -- Convert negatives for range checking
        if i < 0 then
    if i < 0 then
            i = len + i + 1;
    i = len + i + 1
        end
    end
        if j < 0 then
    if j < 0 then
            j = len + j + 1;
    j = len + j + 1
        end
    end
       
     
        if i > len or j > len or i < 1 or j < 1 then
    if i > len or j > len or i < 1 or j < 1 then
            return str._error( 'String subset index out of range' );
    return str._error( 'String subset index out of range' )
        end
    end
        if j < i then
    if j < i then
            return str._error( 'String subset indices out of order' );
    return str._error( 'String subset indices out of order' )
        end
    end
       
     
        return mw.ustring.sub( s, i, j )
    return mw.ustring.sub( s, i, j )
    end
    end


    Line 101: Line 101:
    ]]
    ]]
    function str.sublength( frame )
    function str.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 )
        return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )
    return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )
    end
     
    --[[
    _match
     
    This function returns a substring from the source string that matches a
    specified pattern. It is exported for use in other modules
     
    Usage:
    strmatch = require("Module:String")._match
    sresult = strmatch( s, pattern, start, match, plain, nomatch )
     
    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.
     
    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
     
    ]]
    -- This sub-routine is exported for use in other modules
    function str._match( s, pattern, start, match_index, plain_flag, nomatch )
    if s == '' then
    return str._error( 'Target string is empty' )
    end
    if pattern == '' then
    return str._error( 'Pattern string is empty' )
    end
    start = tonumber(start) or 1
    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
    end


    Line 109: Line 202:
    match
    match


    This function returns a substring from the source string that matches a  
    This function returns a substring from the source string that matches a
    specified pattern.
    specified pattern.


    Line 115: Line 208:
    {{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output}}
    {{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output}}
    OR
    OR
    {{#invoke:String|pos|s=source_string|pattern=pattern_string|start=start_index
    {{#invoke:String|match|s=source_string|pattern=pattern_string|start=start_index
         |match=match_number|plain=plain_flag|nomatch=nomatch_output}}
         |match=match_number|plain=plain_flag|nomatch=nomatch_output}}


    Line 123: Line 216:
         start: The index within the source string to start the search.  The first
         start: The index within the source string to start the search.  The first
             character of the string has index 1.  Defaults to 1.
             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  
         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  
             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  
             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
             counting from the last match.  Hence match = -1 is the same as requesting
             the last match.  Defaults to 1.
             the last match.  Defaults to 1.
    Line 133: Line 226:


    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 each string.  In some circumstances this is desirable, in  
    trailing whitespace from each string.  In some circumstances this is desirable, in
    other cases one may want to preserve the whitespace.
    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
    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.
    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  
    If one adds the parameter ignore_errors=true, then the error will be suppressed and
    an empty string will be returned on any failure.
    an empty string will be returned on any failure.


    Line 148: Line 241:


    ]]
    ]]
    -- This is the entry point for #invoke:String|match
    function str.match( frame )
    function str.match( frame )
        local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain', 'nomatch'} );
    local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain', 'nomatch'} )
        local s = new_args['s'] or '';
    local s = new_args['s'] or ''
        local start = tonumber( new_args['start'] ) or 1;
    local start = tonumber( new_args['start'] ) or 1
        local plain_flag = str._getBoolean( new_args['plain'] or false );
    local plain_flag = str._getBoolean( new_args['plain'] or false )
        local pattern = new_args['pattern'] or '';
    local pattern = new_args['pattern'] or ''
        local match_index = math.floor( tonumber(new_args['match']) or 1 );
    local match_index = math.floor( tonumber(new_args['match']) or 1 )
        local nomatch = new_args['nomatch'];
    local nomatch = new_args['nomatch']
       
     
        if s == '' then
    return str._match( s, pattern, start, match_index, plain_flag, nomatch )
            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
    end


    Line 231: Line 269:


    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.  In some circumstances this is desirable, in  
    trailing whitespace from the target string.  In some circumstances this is desirable, in
    other cases one may want to preserve the whitespace.
    other cases one may want to preserve the whitespace.


    The first character has an index value of 1.
    The first character has an index value of 1.


    If one requests a negative value, this function will select a character by counting backwards  
    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.
    from the end of the string.  In other words pos = -1 is the same as asking for the last character.


    Line 242: Line 280:
    ]]
    ]]
    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'} )
        local target_str = new_args['target'] or '';
    local target_str = new_args['target'] or ''
        local pos = tonumber( new_args['pos'] ) or 0;
    local pos = tonumber( new_args['pos'] ) or 0


        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 str._error( 'String index out of range' );
    return str._error( 'String index out of range' )
        end  
    end
       
     
        return mw.ustring.sub( target_str, pos, pos );
    return mw.ustring.sub( target_str, pos, pos )
    end
    end


    Line 257: Line 295:


    This function duplicates the behavior of {{str_find}}, including all of its quirks.
    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  
    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.
    new code and templates.  New code is recommended to use the "find" function instead.


    Line 268: Line 306:
    ]]
    ]]
    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'} )
        local source_str = new_args['source'] or '';
    local source_str = new_args['source'] or ''
        local target_str = new_args['target'] 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


        if target_str == '' then
    return start
            return 1;
        end   
       
        local start = mw.ustring.find( source_str, target_str, 1, true )
        if start == nil then
            start = -1
        end
       
        return start
    end
    end


    Line 303: Line 341:


    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 parameter.  In some circumstances this is desirable, in  
    trailing whitespace from the parameter.  In some circumstances this is desirable, in
    other cases one may want to preserve the whitespace.
    other cases one may want to preserve the whitespace.


    This function returns the first index >= "start" where "target" can be found  
    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  
    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 returns 0.  If either "source" or "target" are missing / empty, this
    function also returns 0.
    function also returns 0.
    Line 314: Line 352:
    ]]
    ]]
    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' } )
        local source_str = new_args['source'] or '';
    local source_str = new_args['source'] or ''
        local pattern = new_args['target'] or '';
    local pattern = new_args['target'] or ''
        local start_pos = tonumber(new_args['start']) or 1;
    local start_pos = tonumber(new_args['start']) or 1
        local plain = new_args['plain'] or true;
    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 source_str == '' or pattern == '' then
        if start == nil then
    return 0
            start = 0
    end
        end
     
       
    plain = str._getBoolean( plain )
        return start
     
    local start = mw.ustring.find( source_str, pattern, start_pos, plain )
    if start == nil then
    start = 0
    end
     
    return start
    end
    end


    Line 352: Line 390:
         count: The number of occurences to replace, defaults to all.
         count: The number of occurences to replace, defaults to all.
         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' } )
        local source_str = new_args['source'] or '';
    local source_str = new_args['source'] or ''
        local pattern = new_args['pattern'] or '';
    local pattern = new_args['pattern'] or ''
        local replace = new_args['replace'] or '';
    local replace = new_args['replace'] or ''
        local count = tonumber( new_args['count'] );
    local count = tonumber( new_args['count'] )
        local plain = new_args['plain'] or true;
    local plain = new_args['plain'] or true
           
     
        if source_str == '' or pattern == '' then
    if source_str == '' or pattern == '' then
            return source_str;
    return source_str
        end  
    end
        plain = str._getBoolean( plain );
    plain = str._getBoolean( plain )


        if plain then
    if plain then
            pattern = str._escapePattern( pattern );
    pattern = str._escapePattern( pattern )
            replace = mw.ustring.gsub( replace, "%%", "%%%%" ); --Only need to escape replacement sequences.
    replace = mw.ustring.gsub( replace, "%%", "%%%%" ) --Only need to escape replacement sequences.
        end
    end
       
        local result;


        if count ~= nil then
    local result
            result = mw.ustring.gsub( source_str, pattern, replace, count );
        else
            result = mw.ustring.gsub( source_str, pattern, replace );
        end       


        return 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
    end


    --[[  
    --[[
         simple function to pipe string.rep to templates.
         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
    --[[
    escapePattern
    This function escapes special characters from a Lua string pattern. See [1]
    for details on how patterns work.
    [1] https://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
    Usage:
    {{#invoke:String|escapePattern|pattern_string}}
    Parameters
        pattern_string: The pattern string to escape.
    ]]
    function str.escapePattern( frame )
    local pattern_str = frame.args[1]
    if not pattern_str then
    return str._error( 'No pattern string specified' )
    end
    local result = str._escapePattern( pattern_str )
    return result
    end
    --[[
    count
    This function counts the number of occurrences of one string in another.
    ]]
    function str.count(frame)
    local args = str._getParameters(frame.args, {'source', 'pattern', 'plain'})
    local source = args.source or ''
    local pattern = args.pattern or ''
    local plain = str._getBoolean(args.plain or true)
    if plain then
    pattern = str._escapePattern(pattern)
    end
    local _, count = mw.ustring.gsub(source, pattern, '')
    return count
    end
    --[[
    endswith
    This function determines whether a string ends with another string.
    ]]
    function str.endswith(frame)
    local args = str._getParameters(frame.args, {'source', 'pattern'})
    local source = args.source or ''
    local pattern = args.pattern or ''
    if pattern == '' then
    -- All strings end with the empty string.
    return "yes"
    end
    if mw.ustring.sub(source, -mw.ustring.len(pattern), -1) == pattern then
    return "yes"
    else
    return ""
    end
    end
    --[[
    join


    function str.rep( frame )
    Join all non empty arguments together; the first argument is the separator.
        local repetitions = tonumber( frame.args[2] )
    Usage:
        if not repetitions then  
    {{#invoke:String|join|sep|one|two|three}}
            return str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args[2] or '' ) .. '"' )
    ]]
        end
    function str.join(frame)
        return string.rep( frame.args[1] or '', repetitions )
    local args = {}
    local sep
    for _, v in ipairs( frame.args ) do
    if sep then
    if v ~= '' then
    table.insert(args, v)
    end
    else
    sep = v
    end
    end
    return table.concat( args, sep or '' )
    end
    end


    Line 402: Line 519:
    ]]
    ]]
    function str._getParameters( frame_args, arg_list )
    function str._getParameters( frame_args, arg_list )
        local new_args = {};
    local new_args = {}
        local index = 1;
    local index = 1
        local value;
    local value
       
     
        for i,arg in ipairs( arg_list ) do
    for _, arg in ipairs( arg_list ) do
            value = frame_args[arg]
    value = frame_args[arg]
            if value == nil then
    if value == nil then
                value = frame_args[index];
    value = frame_args[index]
                index = index + 1;
    index = index + 1
            end
    end
            new_args[arg] = value;
    new_args[arg] = value
        end
    end
       
     
        return new_args;
    return new_args
    end      
    end


    --[[
    --[[
    Line 422: Line 539:
    ]]
    ]]
    function str._error( error_str )
    function str._error( error_str )
        local frame = mw.getCurrentFrame();
    local frame = mw.getCurrentFrame()
        local error_category = frame.args.error_category or 'Errors reported by Module String';
    local error_category = frame.args.error_category or 'Errors reported by Module String'
        local ignore_errors = frame.args.ignore_errors or false;
    local ignore_errors = frame.args.ignore_errors or false
        local no_category = frame.args.no_category or false;
    local no_category = frame.args.no_category or false
       
     
        if str._getBoolean(ignore_errors) then
    if str._getBoolean(ignore_errors) then
            return '';
    return ''
        end
    end
       
     
        local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>';
    local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>'
        if error_category ~= '' and not str._getBoolean( no_category ) then
    if error_category ~= '' and not str._getBoolean( no_category ) then
            error_str = '[[Category:' .. error_category .. ']]' .. error_str;
    error_str = '[[Category:' .. error_category .. ']]' .. error_str
        end      
    end
       
     
        return error_str;
    return error_str
    end
    end


    Line 443: Line 560:
    ]]
    ]]
    function str._getBoolean( boolean_str )
    function str._getBoolean( boolean_str )
        local boolean_value;
    local boolean_value
       
     
        if type( boolean_str ) == 'string' then
    if type( boolean_str ) == 'string' then
            boolean_str = boolean_str:lower();
    boolean_str = boolean_str:lower()
            if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'  
    if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'
                    or boolean_str == '' then
    or boolean_str == '' then
                boolean_value = false;
    boolean_value = false
            else
    else
                boolean_value = true;
    boolean_value = true
            end  
    end
        elseif type( boolean_str ) == 'boolean' then
    elseif type( boolean_str ) == 'boolean' then
            boolean_value = boolean_str;
    boolean_value = boolean_str
        else
    else
            error( 'No boolean value found' );
    error( 'No boolean value found' )
        end  
    end
        return boolean_value
    return boolean_value
    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" )
    end
    end


    return str
    return str

    Latest revision as of 11:43, 21 May 2021

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

    --[[
    
    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].
    
        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
    
    	return mw.ustring.sub( s, i, j )
    end
    
    --[[
    This function implements that features of {{str sub old}} and is kept in order
    to maintain these older templates.
    ]]
    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
    
    --[[
    _match
    
    This function returns a substring from the source string that matches a
    specified pattern. It is exported for use in other modules
    
    Usage:
    strmatch = require("Module:String")._match
    sresult = strmatch( s, pattern, start, match, plain, nomatch )
    
    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.
    
    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
    
    ]]
    -- This sub-routine is exported for use in other modules
    function str._match( s, pattern, start, match_index, plain_flag, nomatch )
    	if s == '' then
    		return str._error( 'Target string is empty' )
    	end
    	if pattern == '' then
    		return str._error( 'Pattern string is empty' )
    	end
    	start = tonumber(start) or 1
    	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
    
    --[[
    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|match|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
    
    ]]
    -- This is the entry point for #invoke:String|match
    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']
    
    	return str._match( s, pattern, start, match_index, plain_flag, nomatch )
    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
    
    --[[
    escapePattern
    
    This function escapes special characters from a Lua string pattern. See [1]
    for details on how patterns work.
    
    [1] https://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
    
    Usage:
    {{#invoke:String|escapePattern|pattern_string}}
    
    Parameters
        pattern_string: The pattern string to escape.
    ]]
    function str.escapePattern( frame )
    	local pattern_str = frame.args[1]
    	if not pattern_str then
    		return str._error( 'No pattern string specified' )
    	end
    	local result = str._escapePattern( pattern_str )
    	return result
    end
    
    --[[
    count
    This function counts the number of occurrences of one string in another.
    ]]
    function str.count(frame)
    	local args = str._getParameters(frame.args, {'source', 'pattern', 'plain'})
    	local source = args.source or ''
    	local pattern = args.pattern or ''
    	local plain = str._getBoolean(args.plain or true)
    	if plain then
    		pattern = str._escapePattern(pattern)
    	end
    	local _, count = mw.ustring.gsub(source, pattern, '')
    	return count
    end
    
    --[[
    endswith
    This function determines whether a string ends with another string.
    ]]
    function str.endswith(frame)
    	local args = str._getParameters(frame.args, {'source', 'pattern'})
    	local source = args.source or ''
    	local pattern = args.pattern or ''
    	if pattern == '' then
    		-- All strings end with the empty string.
    		return "yes"
    	end
    	if mw.ustring.sub(source, -mw.ustring.len(pattern), -1) == pattern then
    		return "yes"
    	else
    		return ""
    	end
    end
    
    --[[
    join
    
    Join all non empty arguments together; the first argument is the separator.
    Usage:
    {{#invoke:String|join|sep|one|two|three}}
    ]]
    function str.join(frame)
    	local args = {}
    	local sep
    	for _, v in ipairs( frame.args ) do
    		if sep then
    			if v ~= '' then
    				table.insert(args, v)
    			end
    		else
    			sep = v
    		end
    	end
    	return table.concat( args, sep or '' )
    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 _, 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