0031481: Data Exchange - provide parser of STEP EXPRESS schema for generation of new STEP entities

Integration of ExpToCas tool ported to modern state of OCCT:
- new package Express and toolkit TKExpress for EXPRESS data structures and OCCT class generator
- executable ExpToCasExe including lax/yacc parsers, for parsing a Part 21 file and generating classes

Formatting added files from package Express following OCCT Coding Rules

Changes for correspondence generated files to OCCT Code Rules.

Add generation hxx files with declaration of arrays.
If field is a HArray1 method for get length of array and method for get element of array by its index are generated.

Changes for generation parser from Lex and YACC files.

Update description file ReadMe.md

src/Express/Express_Entity.hxx

@@ -0,0 +1,114 @@
+// Copyright (c) 1999-2020 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _Express_Entity_HeaderFile
+#define _Express_Entity_HeaderFile
+
+#include <Express_Item.hxx>
+#include <Standard_OStream.hxx>
+#include <Standard_Type.hxx>
+#include <TColStd_HSequenceOfHAsciiString.hxx>
+#include <NCollection_DataMap.hxx>
+
+class Express_HSequenceOfEntity;
+
+class Express_HSequenceOfField;
+
+class Dico_DictionaryOfInteger;
+
+//! Implements ENTITY item of the EXPRESS
+//! schema, with interface for deferred Item class.
+class Express_Entity : public Express_Item
+{
+
+public:
+
+  //! Create ENTITY item and initialize it
+  //! flags hasCheck and hasFillShared mark if generated class has
+  //! methods Check and FillShared correspondingly.
+  Standard_EXPORT Express_Entity (const Standard_CString theName,
+                                  const Handle(TColStd_HSequenceOfHAsciiString)& theInherit,
+                                  const Handle(Express_HSequenceOfField)& theFields);
+
+  //! Returns sequence of inherited classes (names)
+  Standard_EXPORT const Handle(TColStd_HSequenceOfHAsciiString)& SuperTypes() const;
+
+  //! Returns sequence of inherited items
+  Standard_EXPORT const Handle(Express_HSequenceOfEntity)& Inherit() const;
+
+  //! Returns sequence of fields
+  Standard_EXPORT const Handle(Express_HSequenceOfField)& Fields() const;
+
+  //! Returns number of fields (only own fields if inherited is False
+  //! and including fields of all supertypes if it is True)
+  Standard_EXPORT Standard_Integer NbFields (const Standard_Boolean theInherited = Standard_False) const;
+
+  //! Sets abstruct flag for entity;
+  Standard_EXPORT void SetAbstractFlag (const Standard_Boolean theIsAbstract);
+
+  //! Returns abstract flag.
+  Standard_EXPORT inline Standard_Boolean AbstractFlag() const;
+
+  DEFINE_STANDARD_RTTIEXT(Express_Entity, Express_Item)
+
+protected:
+
+private:
+
+  typedef NCollection_DataMap<TCollection_AsciiString, Standard_Integer, TCollection_AsciiString> DataMapOfStringInteger;
+
+  //! Create HXX/CXX files from item
+  Standard_EXPORT virtual Standard_Boolean GenerateClass() const Standard_OVERRIDE;
+
+  //! Propagates the calls of Use function
+  Standard_EXPORT virtual void PropagateUse() const Standard_OVERRIDE;
+
+  //! Writes includes section of HXX
+  Standard_EXPORT Standard_Boolean writeIncludes (Standard_OStream& theOS) const;
+
+  //! Writes code for reading all fields
+  Standard_EXPORT Standard_Integer writeRWReadCode (Standard_OStream& theOS,
+                                                    const Standard_Integer theStart,
+                                                    const Standard_Integer theOwn) const;
+
+  //! Writes code for writing all fields
+  Standard_EXPORT Standard_Integer writeRWWriteCode (Standard_OStream& theOS,
+                                                     const Standard_Integer theStart,
+                                                     const Standard_Integer theOwn) const;
+
+  //! Writes code for adding shared entities to the graph
+  Standard_EXPORT Standard_Integer writeRWShareCode (Standard_OStream& theOS,
+                                                     const Standard_Integer theStart,
+                                                     const Standard_Integer theOwn) const;
+
+  //! Writes arguments and code for method Init()
+  //! Mode identifies what code is being written:
+  //! 0 - HXX declaration
+  //! 1 - CXX declaration
+  //! 2 - call (argument list)
+  //! 3 - implementation
+  //! 4 - call (argument list for RW)
+  Standard_EXPORT Standard_Integer makeInit (Standard_OStream& theOS,
+                                             const Standard_Integer theShift,
+                                             const Standard_Integer theOwn,
+                                             const Standard_Integer theMode) const;
+
+private:
+
+  Handle(TColStd_HSequenceOfHAsciiString) mySupers;
+  Handle(Express_HSequenceOfEntity) myInherit;
+  Handle(Express_HSequenceOfField) myFields;
+  Standard_Boolean myIsAbstract;
+};
+
+#endif // _Express_Entity_HeaderFile