man RefDB::Makestyle (3): methods used by refdb-ms (RefDB style generator)

SUMMARY

Makestyle.pm - a module used by refdb-ms (RefDB MakeStyle) --- a utility that generates RefDB bibliography styles.

Provides "Element" and "Attribute" classes for use in generating RefDB styles.

DEPENDENCIES

The following perl modules are required by this library:

Scalar::Util
Provides a method of querying an object to determine its base class.
Term::Clui
Provides user interface.
For input it provides mechanisms for selection from menus, direct input and for yes/no question-answer prompts.
For output it provides for console output or display in the default editor.
This module, by default, records user choices in a hidden database. This behaviour is turned off.
Term::Clui::edit uses a console editor for display. It uses the editor specified by the EDITOR variable. If this variable is not set it falls back to the 'vi' editor.
Text::Wrap
Provides word-wrap for console display.
File::Temp
Provides useful methods for filename generation.
The OO methods are not used because, at the time of writing, the version shipped with some *nix-like OSes does not yet include the OO interface.

UNIVERSAL METHODS

These methods are supplied by a hidden base class.

get_classname
Returns classname of object.
_is_valid_value
Default method for determining validity of simple (scalar) user input. Checks that value is defined and not an empty string and not filled with whitespace.
Is overridden by derived classes with more stringent input requirements.

_input_choice

User selects from a menu.

Returns user's selection.

Parameters: (0 = class), 1 = prompt, 2... = options.

Common usage:

        my $value = undef;
        while ( 1 ) {
                $value = $self->_input_choice( "Select value:" , <@list> );
                if ( $value ) { last; }
                print "Invalid choice.  Sorry, please try again.\n";
        }

_input_ask

User enters a value.

Returns user's input.

Parameters: (0 = class), 1 = prompt, 2 = default.

Common usage:

        my $value = undef;
        while ( 1 ) {
                $value = $self->_input_ask( "Enter value:" , <$default> );
                if ( $self->_is_valid_value( $value ) ) { last; }
        }

_input_confirm
User is asked a question to which s/he answers y/n.
Returns boolean.
Parameters: (0 = class), 1 = question.
Note: If multi-line question, then after answer only the first line is left on screen. The first line should be a short question with subsequent lines holding further information.
Common usage:
```
        if (_input_confirm( "Short question?\n\nMore\nmulti-line\ntext." ) ) {
                # do stuff
        }
```
_display
Displays screen text with word wrapping.
Parameters: (0 = class), 1 = display string.
Common usage:
```
        _display( <$scalar> );
```
_view
Displays large volume of text in default editor and then returns viewer to original screen.
Parameters: (0 = class), 1 = title , 2 = help text.
Common usage:
```
        _view( <$title> , <$help_text> );
```
_entitize
Takes string and replaces '&', '<' and '>' with xml entity equivalents.

ATTRIBUTE CLASSES

These classes model the XML attributes found in the Refdb "citestylex" DTD.

Attributes: Public Interface

Attributes: Data Members

        %self = (
                name          =>  "ATTRIBUTE" ,
                enumeration   =>  [ "value_0" , "value_1" , ... ] ,
                default       =>  "value_x" , 
                prompt        =>  "This is the purpose and/or use of the attribute." ,
                value         =>  "User selected/entered value>" ,
                summary       =>  0 | 1 ,
        )

name
Attribute name as per the Refdb "citestylex" DTD. Always uppercase.
enumeration
List of possible values for attribute. If empty then attribute takes user-entered value, eg. DISPLAYAUTHOR, which takes a number.
default
The default value. If "enumeration" is present, the default will always be one of the items in it. If no default then leave as "undef" --- this is the 'default' value after object construction.
prompt
The text string that is used by client methods to prompt users when entering data.
summary
Boolean determining whether attribute is included in summary form.
value
The attribute value as selected or input by the user.

Attributes: Constructors

In following method signatures replace ATTRIBUTE with the relevant attribute class name.

Some attributes have a maximum number of instances that can exist within a given PubType (see method select_value below). When a class is asked to create an object in excess of the designed maximum for that class the constructor returns a scalar holding an error message. This enables a simple test (using "ref" function) to determine whether the constructor returned an object/blessed variable or scalar.

        my $at = ATTRIBUTE->new();

Attributes: Setters

        $at->set_name        ( "<name>"    );
        $at->set_default     ( "<default>" );
        $at->set_prompt      ( "<prompt>"  );
        $at->add_enumeration ( LIST        );
        $at->set_summary     ( 0 | 1       );

Attributes: Getters

        $at->get_name();
        $at->get_default();
        $at->get_prompt();
        $at->get_enumeration();  # returns list with default value first
        $at->get_enum_string();  # returns single text string
        $at->get_summary();
        $at->get_value();

Attributes: Other methods

$at->select_value();
If enumeration exists then user selects from list. The default is always the first option in the list.
If there is no enumeration the user enters the value directly. The default value is given and can be selected by simply pressing "Enter".
Some attributes are set automatically depending on how many objects of this class have been created. In those classes this method has no effect. This applies to the Role_AuthorList, Role_PubDate, Role_Title, Role_UserDef, Role_Link and Role_Misc classes.
The "citestylex" DTD design envisages a maximum number of objects of these classes being constructed --- the number varying between 3 and 5 depending on the class. See ``Attributes: Constructors'' for what happens when the class is asked to create an object in excess of the designed maximum.
$at->get_xml_fragment();
Returns minimal xml fragment indicating the attribute name and value:
```
        ATTRIBUTE="VALUE"
```

Attributes: List of Classes

To see a list of attribute classes use the "document-dtd-entities" utility that shipped with this program. It extracts attribute and element properties from this script, assembles and formats them into a single html document.

ELEMENT CLASSES

These classes model the XML elements found in the Refdb "citestylex" DTD.

Elements: Public Interface

Elements: Data members

        %self = (
                name          =>  "ELEMENT" ,
                prompt        =>  "This is the purpose of this element." ,
                help          =>  "This is help on how to use this element." ,
                display       =>  undef | "name" | "content" ,
                summary       =>  undef | "name" | "left" | "right" | "content" ,
                
                attributes    =>  {
                        mandatory     =>  [ "Attribute_Class_0" , "Attribute_Class_1" , ... ] ,
                        optional      =>  [ "Attribute_Class_0" , "Attribute_Class_1" , ... ] ,
                        selected      =>  [ "Attribute_0" , "Attribute_1" , ... ] ,
                        man_complete  =>  undef | 1 ,
                        opt_complete  =>  undef | 1 ,
                } ,
                copyable      =>  1 | undef , 
                
                content       =>  {
                        allowed       =>  undef | 1 ,
                        suggestion    =>  "Possible value" ,
                        value         =>  "User input" ,
                        complete      =>  undef | 1 ,
                
                } ,
                model_order   =>  [
                        
                        [ Element_Class_0 , "? | + | 1" ] ,
                        [ Element_Class_1 , "? | + | 1" ] ,
                        ... ,
                ] ,
                model_noorder =>  {
                        element_list =>  [ Element_Class_0 , Element_Class_1 , ... ] ,
                        separator    =>  "Separator" ,
                } ,
                children      =>  {
                        elements     =>  [ Element_0 , Element_1 , ... ] ,
                        complete     =>  boolean ,
        )

name
Element name as given in the Refdb "citestylex" DTD. Unique.
prompt
Brief statement of the element's purpose and/or function.
help
More detailed instructions on how to use this element.
display
Determines whether, and how, to display the element in brief form (used for the ``progress report''. If defined, the element is displayed. If set to ``name'' the element name is displayed. If set to ``content'' the element contents are displayed.
summary
Determines whether, and how, to display the element in summary form. If defined, the element is displayed. If set to ``name'' the element name is displayed. If set to ``content'' the element contents are displayed.
attributes
Attributes of this element. First two lists are of 'legal' attributes: mandatory and optional. Third list is of added attribute objects --- initially empty. Fourth and fifth hash values are flags indicating whether attributes have been added.
content
Some elements hold #PCDATA content. The hash key "allowed" determines whether element accepts input --- false/undef means it does not, true means it does. The hash key "suggested" holds a suggested value the user may use. The hash key "value" holds the actual user input. The hash key "complete" is a flag indicating whether content has been entered.
copyable
Some elements cannot be copied, either because they have mandatory attributes which require user input or because they only occur once per citstyle.
model_order
With model_noorder this data member determines the content model for children elements. All of the 64 elements fall into one of three content models regarding children elements: 1. No children elements, 2. An ordered list and 3. An unordered list.
This data member is "undef" in cases (1) and (3).
It holds the content model for the thirty elements which have content model (2) --- an ordered list:
```
        ( e[?|+|1] , e[?|+|1] , ... )
```
where 'e' is the element and the symbols indicate 0-1, 1 or more, and exactly 1 occurrence, respectively.
This data member holds an array of arrays. Each secondary array has two items: the element class and the number of objects that can be children.
model_noorder
With model_order this data member determines the content model for children elements. All of the 64 elements fall into one of three content models regarding children elements: 1. No children elements, 2. An ordered list and 3. An unordered list.
This data member is "undef" in cases (1) and (2).
It holds the content model for the four elements (AUTHORONLY, INTEXTDEF, PUBTYPE and YEARONLY) which have content model (3) --- an unordered list:
```
        ( ( e | e | ... ) , e? )+
```
where 'e' is an element, '?' is 0 or 1 occurrence and '+' is 1 or more occurrances.
This data member holds a hash where the first key points to an array holding the list of alterate elements in the content model inner brackets. The second key points to the element represented in the content model as 'e+' (in every case it is SEPARATOR).
children
This data member holds a hash. The first hash key (``elements'') points to an array holding the children elements added by the user. The second hash key (``complete'') is a boolean indicating whether all children have been added.

Elements: Constructors

In following method signatures replace ELEMENT with the relevant element class name.

        my $el = ELEMENT->new();

Elements: Setters

        $el->set_name( "<name>" );
        $el->set_prompt( "<prompt>" );
        $el->set_help( "<help>" );
        $el->set_display( undef | "name" | "content" );
        $el->set_summary( undef | "name" | "left" | "right" | "content" );
        $el->set_attributes( %hash );
        $el->set_mandatory_attributes_complete( "1" | undef );
        $el->set_optional_attributes_complete( "1" | undef );
        $el->set_content( %hash );
        $el->set_content_complete( "1" | undef );
        $el->set_order( @ArrayOfArrays );
        $el->set_noorder( %hash );
        $el->set_complete( "1" | "0" | undef );
        $el->_set_value( "<value>" );

Elements: Getters

        $el->get_name();
        $el->get_prompt();
        $el->get_help();
        $el->get_display();
        $el->get_summary();
        $el->get_attr_mandatory();  # list:   $self->{attributes}->{mandatory}
        $el->get_attr_optional();   # list:   $self->{attributes}->{optional}
        $el->get_attr_selected();   # list:   $self->{attributes}->{selected}
        $el->get_suggestion();      # scalar: $self->{content}->{suggestion}
        $el->get_value();           # scalar: $self->{content}->{value}
        $el->get_order();           # AoA:    $self->{model_order}
        $el->get_noorder_list();    # list:   $self->{model_noorder}->{element_list}
        $el->get_noorder_separator; # scalar: $self->{model_noorder}->{separator}
        $el->get_children();        # list:   $self->{children}->{element}
        $el->get_last_child();      # object: $self->{children}->{element}[<last>]

Elements: Other methods

$el->content_is_complete();
Returns boolean indicating whether element content has been entered.
Indicated by a data member which is set after "enter_value()" method called.
$el->enter_value();
User enters element value if element can legally hold one. User may be presented with a suggested value.
If the element cannot accept a value nothing happens --- no error message/value is generated.
$el->is_content_allowed();
Returns boolean indicating whether the element can hold content.
$el->children_are_complete();
Returns boolean indicating whether all children have been added.
Simply returns $self->{children}->{complete} and relies on other subroutines having set it appropriately.
$el->max_attribute_index();
Returns maximum index value of selected attributes list: -1 if empty list.
$el->max_child_index();
Returns maximum index value of element children list: -1 if empty list.
$el->is_last_element();
Determines whether element index is the last element in the list of children in the ordered child model: $self->{model_order}.
Parameters: [ 0 = class ] , 1 = array index.
$el->is_last_child();
Determines whether child index is the last element in the list of children: $self->{children}->{elements}.
Parameters: [ 0 = class ] , 1 = array index.
$el->is_creatable();
Returns a boolean indicating whether this element class can legally create another object.
Intended to be called as a class method.
$el->list_selectable_attributes();
Returns a list of all optional attributes available for selection. List consists of all attributes listed in 'optional' list minus all attributes already selected.
$el->_build_attribute_help();
Helper method for method "add_attributes_optional". Takes as parameter a list of attributes for which help screen is being built. Includes "name" and "prompt" for each attribute.
$el->has_mandatory_attributes();
Returns boolean indicating whether element has mandatory attributes.
$el->_is_closed_tag();
Returns boolean indicating whether element can be represented by closed tag. Requires no possible child elements and no current content.
$el->get_xml_brief_tag();
Returns opening xml tag for element.
Shows only mandatory attributes.
$el->get_xml_open_tag();
Returns opening xml tag for element.
Parameters: [ 0 = class ] , 1 = show attributes (bool) , 2 = show content (bool).
Designed to be used in conjunction with "get_xml_close_tag" method. If element has no potential child elements and no content, then will return closed tag, eg. <ELEMENT/>.
$el->get_xml_close_tag();
Returns closing xml tag for element.
Designed to be used in conjunction with "get_xml_open_tag" method. If element has no potential child elements and no content, then will return no closing tag since "get_xml_open_tag" will have returned a closed tag, eg. <ELEMENT/>.
$el->generate_full_xml();
Generates full xml for element.
Displays all attributes and element content. If no possible child elements and no current element content, will display closed tag, eg. <ELEMENT/>.
Method is recursive.
Parameters (receives): [ 0 = class ] , 1 = element count , 2 = indent/tab count and 3 = output.
Returns: 0 = element count and 1 = output.
$el->get_a_child();
Returns a single child element matching supplied array index. Returns "undef" if index out of bounds.
Parameter: [ 0 = class ] , 1 = index.

$el->show_progress();

Generates abbreviated xml for element and element children. Designed to show user's ``progress'' to date.

Displays only opening tags. Child elements are displayed only where element is not set to ``complete''.

Only mandatory attributes are displayed.

Method is recursive.

Parameters (receives): [ 0 = class ] , 1 = output , 2 = stop flag.

Returns: 0 = output.

Algorithm (recursive):

        if self is a stop element
                set stop flag = true
        endif
        add self to output
        if stop flag == true  and  children are complete
                return 'output'
        else
                repeat for all children
                        recurse (returns 'output')
                endrepeat
                return 'output'
        endif
        if matching element
                set stop flag = true
        endif
        add to output
        if stop flag true
                if is complete
                        if has children
                                recurse
                        else
                                add fragment to output
                        endif
                else  # not complete
                        
        if has children
                repeat for all children
                        recurse (returns 'retval')
                        set output = 'retval'
                endrepeat
        endif
        return output

$el->generate_brief_xml();
Generates abbreviated xml for element. Designed to show user's ``progress'' to date.
Displays only opening tags. Child elements are displayed only where element is not set to ``complete''.
Only mandatory attributes are displayed.
Method is recursive.
Parameters (receives): [ 0 = class ] and 1 = output.
Returns: 0 = output.
$el->get_full_tag();
Returns opening +/- closing xml tag for element.
Displays all attributes and element content. If no possible child elements and no current content, will display single closed tag, eg. <ELEMENT/>.
$el->_test_attributes_mandatory();
Intended as helper method for "is_creatable". Tests that mandatory attributes can be created.
Note: The attributes are not actually added to the element.
Returns boolean. False value indicates failure adding mandatory attributes and the associated element should be detroyed.
$el->add_attributes_mandatory();
Mandatory attributes are immediately added (note: mandatory attributes should have been added during element construction).
Returns boolean. False value indicates failure adding mandatory attributes and the associated element should be detroyed.
Can be run in 'silent' mode with no output from method. There are no guarantees about the 'silence' of attributes' "select_value" method, but all such methods should not generate output.
Parameters: [ 0 = class ] , [ 1 = <text> | 1 ]
$el->add_attributes_optional();
The user selects optional attributes to add. Help is available. Element feedback is presented as the user proceeds.
$el->mandatory_attributes_complete();
Returns boolean indicating whether mandatory attributes have been added.
Indicated by a data member which is set after "add_attributes()" method called.
$el->optional_attributes_complete();
Returns boolean indicating whether optional attributes have been added.
Indicated by a data member which is set after "add_attributes()" method called.
$el->add_attributes();
First adds the mandatory attributes and then gives user chance to add optional attributes.
Returns boolean indicating whether attributes added successfully. Only mechanism of failure occurs when element requires mandatory attribute such as ROLE which cannot be added because maximum number of ROLE attributes already exist for this PUBTYPE.
$el->add_child();
Adds a child to the current element.
Parameters: [ 0 = class ] , 1 = child element (object).

$el->_select_next_child_order();

Helper method for method "select_next_child". Used when element has a modal content model. Help is provided where appropriate.

Returns two element list: 0 = message indicating whether selection was forced by the content model or chosen by user , 1 = element class name.

Note: If user makes no selection, and content model forces none, an "undef" element class name is returned along with an informative message.

When content model is exhausted the content flag --- $self->{children}->{complete} --- is set to true.

The algorithm for this subroutine is the nastiest in the program. I include it here in full for future occasions when I may have to debug.

        if no current child elements
                set OUT_OF_CHILDREN = true
        else
                set OUT_OF_CHILDREN = false
        endif
        begin loop
                if OUT_OF_CHILDREN == true
                        switch require
                                case +
                                        if PREV != element
                                                EXIT: mandatory element
                                        else  # ( PREV_CHILD == element )
                                                ASK: repeat element
                                                if yes
                                                        EXIT: chosen element
                                                else  # ( no )
                                                        if last element
                                                                set children_full flag = true
                                                                EXIT: END
                                                        else  # ( not last element )
                                                                advance element
                                                        endif
                                                endif
                                        endif
                                endcase
                                case 1
                                        if last element
                                                set children_full flag = true
                                        endif
                                        EXIT: mandatory element
                                endcase
                                case ?
                                        ASK: add element
                                        if yes
                                                EXIT: chosen element
                                        else  # ( no repeat )
                                                if last element
                                                        set children_full flag = true
                                                        EXIT: END
                                                else  # ( not last element )
                                                        advance element
                                                endif
                                        endif
                                endcase
                        endswitch
                else  # ( OUT_OF_CHILDREN == false )
                        if child == element
                                switch require
                                        case ? | 1
                                                if last child
                                                        if last element
                                                                set children_full flag = true
                                                                EXIT: END
                                                        else  # ( not last element )
                                                                advance element
                                                                set OUT_OF_CHILDREN = true
                                                        endif
                                                else  # ( not last child )
                                                        if last element
                                                                ERROR: exhausted content model but got $child
                                                        else  # ( not last element )
                                                                advance element
                                                                set PREV_CHILD = null
                                                                advance child
                                                        endif
                                                endif
                                        endcase
                                        case +
                                                if last child
                                                        ASK: repeat element
                                                        if yes
                                                                EXIT: optional element
                                                        else  # ( no repeat )
                                                                if last element
                                                                        set children_full flag = true
                                                                        EXIT: END
                                                                else  # ( not last element )
                                                                        advance element
                                                                        set OUT_OF_CHILDREN = true
                                                                endif
                                                        endif
                                                else  # ( not last child )
                                                        set PREV_CHILD = child
                                                        advance child
                                                endif
                                        endcase
                                endswitch
                        else  # ( child != element )
                                switch require
                                        case +
                                                if last element
                                                        ERROR: expecting $element, got $child
                                                else  # ( not last element )
                                                        if PREV_CHILD == element
                                                                set PREV_CHILD = null
                                                                advance element
                                                        else  # ( PREV_CHILD != element )
                                                                ERROR: expecting $element, got $child
                                                        endif
                                                endif
                                        endcase
                                        case ?
                                                if last element
                                                        ERROR: content model exhausted, no match for $child
                                                else  # ( not last element )
                                                        advance element
                                                endif
                                        endcase
                                        case 1
                                                ERROR: expecting $element, got $child
                                        endcase
                                endswitch
                        endif
                endif
        end loop

Warning: In a number of places in this subroutine the program can "die". This occurs when a mismatch between the child element model and the actual child elements is detected. If the mismatch truly exists it is a coding error since the algorithm should force child elements to match the content model. If the mismatch is not real the code has erred in analysing the data. Either way, it is an unrecoverable error and the algorithm/code must be corrected.

$el->list_selectable_children_noorder();
Used when selecting child elements when following the unordered model.
Returns a list of all optional elements available for selection. List consists of all elements attributes listed in 'optional' list minus all attributes already selected.
$el->_build_element_help();
Helper method for method "_select_next_child_noorder". Takes as parameter a list of elements for which help screen is being built.
$el->_select_next_child_noorder();
The user selects optional child element to add.
Helper method for 'select_next_child'.
Returns two element list: 0 = message indicating whether selection was forced by the content model or chosen by user , 1 = element class name.
Note: If user chooses to finish child element selection, "undef" element class name is returned along with an informative message.
When child element selection is finished the content flag --- $self->{children}->{complete} --- is set to true.
Help is available.
No option to exit until at least one element has been selected.
Cannot select two "Separator" elements consecutively.
$el->select_next_child();
The user selects a child element to add. Help is available.
Returns two element list: 0 = text indicating whether mandatory or user choice ,
1 = element class name.
Note: If user makes no selection, and content model forces none, an "undef" element class name is returned along with an informative message.
The algorithm for this subroutine is the nastiest in the program. I include it here in full for future occasions when I may have to debug.
$el->is_copyable();
Returns boolean indicating whether element can be copied.
Based on value of $self->{copyable}.
$el->copy();
Attempts to copy element. Returns either a reference to a copied element or an error message.
Can test for success using "ref" function.
Does not copy attributes. Attributes requiring user input during creation are not copyable (this includes Type_PubType, Role_UserDef, Role_Misc and Role_Link).
Does not copy child elements. For that, use the "duplicate" method.
$el->has_attributes();
Returns boolean indicating whether element has attributes.
$el->has_children();
Returns boolean indicating whether element has children.
$el->_push_attribute();
Adds attribute to element.
Parameters: [ 0 = class ] , 1 = attribute object.
$el->duplicate();
Returns either a reference to a duplicate element or an error message.
Copies all attributes, child elements and element content.
$el->duplicate();
Returns either a reference to a duplicate element or an error message.
Copies all attributes, child elements and element content.
$el->is_ordered_child_model();
Returns boolean indicating nature of child element content model.
$el->is_unordered_child_model();
Returns boolean indicating nature of child element content model.
$el->is_childless_model();
Returns boolean indicating nature of child element content model.

$el->get_last_parent();

Return reference to last parent element.

Parameters: [ 0 = class ] , 1 = originator flag (true if not originating element)

Recursive algorithm:

        if child elements
                recurse last child (returns 'retval')
                if 'retval' is element
                        return 'retval'
                else
                        return self
                endif
        else
                if recursed element
                        return undef
                else
                        return self
                endif
        endif

$el->get_last_element();

Return reference to last element.

Recursive algorithm:

        if child elements
                recurse last child (returns 'retval')
                return 'retval'
        else
                return self
        endif

$el->delete_last_child();
Delete last child of this element.
Returns element.
$el->delete_last_element();
Delete last element.
Return deleted element.
$el->has_incomplete_descendent();
Returns boolean indicating whether any descendent of element is incomplete.

$el->get_last_incomplete();

Return reference to last element in tree that is incomplete.

Returns "undef" if all elements complete.

Recursive algorithm:

        if child elements
                recurse last child (returns 'retval')
                if 'retval' is element
                        return 'retval'
                endif
        else
                if not complete
                        return self
                else
                        return undef
                endif
        endif

$el->is_named();
Returns boolean indicating whether element has display data member set to ``name''.
$el->get_last_named();
Return reference to last element in tree with display data member set to 'name'.
$el->get_style_name();
Finds StyleName element and returns element content.
If unsuccessful, return "undef".
$el->get_most_recent();
Return reference to last element in tree of supplied element class.
If no element found, return "undef".
$el->reset_all_counters();
Resets all role level counters
Called by PubType, AuthorOnly, YearOnly and InTextDef during element creation.
$el->named_in_summary();
Boolean indicating whether to include element in summary.
$el->content_in_summary();
Boolean indicating whether to include raw element content in summary. Currently only applies to SEPARATOR.
$el->has_bracketing_child();
Boolean indicating whether element has any child elements whose content will ``bracket'' this element's content in output. Currently only applies to PRECEEDING and FOLLOWING.

$el->generate_summary();

Generates substantial portion of style summary. Called by UI method 'write_summary'.

Parameters: [ 0 = class ] , 1 = previous output.

Returns: 0 = current output.

Since this method is only called on a complete style, we can make assumptions based on the style following the DTD.

Recursive algorithm.

        switch <element class>
                case 'StyleName'
                        add to output: style name
                endcase
                case 'RefStyle'
                        add to output: header = "Bibliography Style"
                endcase
                case 'PubStyle'
                        add to output: header giving publication type
                endcase
                case 'CitStyle'
                        add to output: header = "Citation Style"
                endcase
                case 'InTextDef'
                        add to output: header = Author and Year
                endcase
                case 'AuthorOnly'
                        add to output: header = Author
                endcase
                case 'YearOnly'
                        add to output: header = Year
                endcase
        endswitch
        if summary flag == name
                if bracketing child element(s)
                        set bracket flag = true
                endif
                if bracket flag == true
                        add to output: opening brackets
                endif
                if bracket flag == true
                        if left bracketing element present
                                print left bracketing element contents
                        endif
                endif
                add to output: left marker
                add to output: element name
                repeat for all attributes
                        if attribute summary flag == true
                                add to output: attribute value (italicised)
                        endif
                endrepeat
                add to output: right marker
        endif
        if have children
                repeat for all children 
                        ** recurse (send output, receive output as 'retval')
                endrepeat
        endif
        return output

Elements: List of Classes

All elements descend from one of three ancestor classes depending on their content model:

_Model_Childless
Elements descended from this class have a content model specifying no children elements.
_Model_Order
Elements descended from this class have a content model of the general form:
```
        ( element_A[?|+] , element_B[?|+] , ... )
```
_Model_Noorder
Elements descended from this class have a content model of the general form:
```
        ( element_A | element_B , ... ) , element_X? )+
```

USER-INTERFACE CLASS

This class holds the user-built bibliography style.

UI: Public Interface

UI: Data members

        %self = (
                help  =>  {
                        
                        <help topic>       =>  <help text> ,
                        ...
                } ,
                cache  =>  {
                        "element_class_A"  =>  element_A ,
                        "element_class_B"  =>  element_B ,
                        ...
                } ,
                root  =>  "undef" | element ,
                
                filename  =>  undef | <filename>,
                
        )

help
Introductory help system.
Is a hash consisting of <``help topic'' : ``help text''> pairs.
cache
Cache for frequently used elements.
First hash key (``cachable'') points to list of cachable elements.
Second has key points to subsidiary hash which holds key:value pairs of element class names and the corresponding element.
root
Location of style's root element.
style_file
Name of style file. Set after successful output.
summary_file
Name of summary file. Set after successful output.

UI: Constructors

        my $ui = UI->new();

UI: Setters

        $ui->set_root( <element> );
        $ui->set_style_file( "<filename>" );
        $ui->set_summary_file( "<filename>" );

UI: Getters

        $ui->get_help_topics();          # list:   keys   ( $self->{help} )
        $ui->get_help( "<topic>" );      # scalar: value  ( $self->{help}->{<topic>} )
                                         #         takes parameter: help topic
        $ui->get_cachable();             # list:   $self->{cache}->{cachable}
        $ui->get_cached();               # list:   defined( $self->{cache}->{elements} )
        $ui->get_cached_element( "<class>" );
                                         # object: cached element
        $ui->get_root();                 # object: root element
        $ui->get_style_file();           # scalar: style file filename
        $ui->get_summary_file();         # scalar: summary file filename

UI: Other methods

$ui->help_system();
Runs help system --- a menu allowing the selection of a series of
$ui->get_last_parent();
Returns reference to last parent element.
$ui->can_copy_recent();
Returns booelan indicating whether element can copy recent version of itself.
Parameters: [ 0 = class ] , 1 = element class | object
$el->delete_selected_element();
Gives the user the option of deleting element(s).
Depending on the state of the element tree, the user can delete the last element or the last major (``named'') element. A ``named'' element has its 'display' data member set to 'name' --- in general they are the elements corresponding to ris fields.
A ``complete'' element has had all children added and its 'children->complete' data member is set to true (``1'').
Algorithm is:
```
        get last named element
        if element is complete
                repeat until last named element is deleted
                        delete last element
                endrepeat
        else
                delete last element only
        endif
```
$ui->create_element();
Creates element. If element of class already exists, user can duplicate most recent.
$ui->startup_checks();
Currently checks for: write access to current directory.
$ui->get_output_filename();
Returns filename for output file. Uses File::Temp module.
If filename does not exist in current directory, simply return default.
If it does, then user must select new filename. File::Temp is used to provide a suggestion based on the default filename.
Requires the following parameters: [ 0 = class ] , 1 = default filename , 2 = filename template pattern , 3 = filename template suffix , 4 = prompt.
Parameters 2 and 3 are in the format required by File::Temp. Parameter 2 must end in at leat 4 'X's --- these will be replaced with random digits. The suffix is the part of the filename following the part specified by parameter 2. It is not restricted to a DOS-style three letter extension.
Example: Default filename (parameter 1) = 'experimental-style.xml'. Filename template pattern (parameter 2) = 'experimental-XXXX'. Filename template suffix (parameter 3) = '-style.xml'. Prompt (parameter 4) = 'Enter name for style file:'.
$ui->write_style();
Writes style to file. Checks filename doesn't already exist. If so, proposes alternative.
$ui->write_summary();
Writes style summary to file. Checks filename doesn't already exist. If so, proposes alternative.
$ui->get_command_base();
Gets base for refdba commands. Involves checking for access to refdba. Also determines whether username and password required.
If succeeds, returns base command of the form:
```
        refdba [-u <username> -w <password>] -C
```
If fails, returns "undef".
$ui->upload_style();
Uploads style to refdb. If style of same name already exists, attempt to save it to disk.

AUTHOR

David Nebauer, david <at> nebauer <dot> org

COPYRIGHT AND LICENSE

This library is distributed under the same license and conditions as the "RefDB" project <<http://refdb.sourceforge.net/>>.

SUMMARY

DEPENDENCIES

UNIVERSAL METHODS

ATTRIBUTE CLASSES

Attributes: Public Interface

Attributes: List of Classes

ELEMENT CLASSES

Elements: Public Interface

Elements: List of Classes

USER-INTERFACE CLASS

UI: Public Interface

AUTHOR

COPYRIGHT AND LICENSE

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