initial commit for github

doc/input/oo-ddl.md

@@ -0,0 +1,63 @@
+# Object-oriented representation of the DDL (OO-DDL) {#page_oo_ddl}
+
+# Introduction
+To facilitate the handling of DDL hierarchies there is an object-oriented
+approach of representation, called OO-DDL.
+
+Within the class structure of OO-DDL every node type inside the DDL definition
+is representated by an own class.
+
+**Note:** 
+
+These classes are associated by using the GoF design patterns "Visitor",
+"Decorator", and "Factory Method". 
+The main classes are described in the following section.
+
+# Structure of classes
+The basic interface of nearly all classes of the OO-DDL is `ddl::IDDL`.
+The root element of every DDL structure is an instance of
+`ddl::cDDLDescription`. For example a DDL Definition File may be
+represented by `cDDLDescription`. This object holds references to the main
+parts like the header (`ddl::cDDLHeader`) or the datatypes
+(`ddl::IDDLDataType`). For further information on all available OO-DDL
+classes see the SDK documentation of `ddl::IDDL`.
+
+Every link between DDL-representing objects is realized as pointer to the
+according object. So lots of string comparisons for matching e.g. child
+elements could be removed.
+
+# Building up - using ddl::IDDLFactoryMethod
+For all creation tasks concerning OO-DDL implementations of the interface
+`IDDLFactoryMethod` are used. A basic implementation of `IDDLFactoryMethod`
+is `ddl::cDDLImporter`.
+
+# Processing DDL - using ddl::IDDLVisitor
+For every task of processing DDL implementations of `ddl::IDDLVisitor` are
+used. Utilizing this interface the DDL-representing hierarchy can be walked
+through and appropriate actions may be taken. The basic implementation of
+`IDDLVisitor` is `ddl::cDDLPrinter`.
+
+# The Correlation Between OO-DDL and DDL.
+Every tag and some attributes in the DDL have a correspondent in the OO-DDL. 
+The following table shows the OO-DDL classes with their matching DDL tag or attribute:
+
+|DDL Tag/Attribute|OO-DDL Class|
+|--- |--- |
+|`<adtf:ddl>`|cDDLDescription|
+|`<header>`|cDDLHeader|
+|`<ext_declaration>`|cDDLExtDeclaration|
+|`<baseunit>`|cDDLBaseunit|
+|`<prefix>`|cDDLPrefix|
+|`<unit>`|cDDLUnit|
+|`<refUnit>`|cDDLRefUnit|
+|`<datatype>`|cDDLDataType|
+|`<enum>`|cDDLEnum|
+|`<struct>`|cDDLComplex|
+|`<element>`|cDDLElement|
+|alignment=xxx|cDDLAlignment|
+|byteorder=xxx|cDDLByteorder|
+|`<stream>`|cDDLStream|
+|`<struct>` (within a `<stream>` tag)|cDDLStreamStruct|
+
+
+