File : sax-models.ads
-- This package implements the content models as described in the DTDs.
-- They are not strictly part of the SAX 2.0 standard, however they are
-- used to simply the handling in users' applications.
with Unicode.CES;
package Sax.Models is
type Content_Spec is
(Character_Data, -- Characters, but no child node (#PCDATA)
Element_Ref, -- A specific child
Any_Of, -- child is one of many choices
Sequence, -- a sequence of elements (order is imposed)
Repeat, -- A repeated element
Empty, -- Element must be empty (EMPTY)
Anything -- Content is not described, and can be anything (ANY)
);
type Element_Model;
type Element_Model_Ptr is access Element_Model;
type Element_Model_Array is array (Natural range <>) of Element_Model_Ptr;
type Element_Model_Array_Ptr is access Element_Model_Array;
type Element_Model (Content : Content_Spec) is record
case Content is
when Character_Data | Empty | Anything => null;
when Element_Ref =>
Name : Unicode.CES.Byte_Sequence_Access; -- Name of the element
when Any_Of | Sequence =>
List : Element_Model_Array_Ptr; -- all the possible choices
when Repeat =>
Min : Natural;
Max : Positive;
Elem : Element_Model_Ptr;
end case;
end record;
-- Type used to describe the model used for an element, as described in
-- the DTD (see 3.2.* in XML specifications). For instance, the following
-- model "(#PCDATA|emph)*" is translated to:
-- (Content => Repeat,
-- Min => 0,
-- Max => Positive'Last,
-- Elem => (Content => Any_Of,
-- Choices => (0 => (Content => Character_Data),
-- 1 => (Content => Element,
-- Name => "emp"))))
procedure Free (Model : in out Element_Model_Ptr);
-- Free the memory allocated for the model.
function To_String (Model : Element_Model) return Unicode.CES.Byte_Sequence;
-- Return the string to put in an XML file to describe Model
-- Invalid_Content_Model is raised if Model can not be described in a
-- DTD.
function Is_Mixed (M : Element_Model_Ptr) return Boolean;
-- Return True if M represents a Mixed content model (3.2.2 in XML
-- specifications).
Invalid_Content_Model : exception;
-- Raised by To_String, when the model is invalid
--------------------------
-- Validating the model --
--------------------------
-- The model can be used as a non-deterministic state machine, so that
-- it can be used for validation
type Model_State is private;
private
type Model_Item;
type Model_List is access Model_Item;
type Model_Item is record
State : Element_Model_Ptr;
Next : Model_List;
end record;
type Model_State is record
Possible_States : Model_List;
end record;
end Sax.Models;