CppGenerator: same header included multiple times

[phoppermann]

If multiple class attributes are objects of the same class, the corresponding header is included multiple times.
See

xmlpg/src/main/java/edu/nps/moves/xmlpg/CppGenerator.java

Line 192 in 11f88b3

for (int idx = 0; idx < aClass.getClassAttributes().size(); idx++) {

Possible solution: store includes in Set<String>.

[phoppermann]

untested:

            // collect includes to avoid duplicates
            Set<String> includes= new HashSet<String>();
            for (int idx = 0; idx < aClass.getClassAttributes().size(); idx++) {
                ClassAttribute anAttribute = (ClassAttribute) aClass.getClassAttributes().get(idx);

                // If this attribute is a class, we need to do an import on that class
                if (anAttribute.getAttributeKind() == ClassAttribute.ClassAttributeType.CLASSREF) {
                    includes.add("#include <" + anAttribute.getType() + ".h>");
                }

                // If this attribute is a list with class type, we also need to do an import on that class
                if ((anAttribute.getAttributeKind() == ClassAttribute.ClassAttributeType.FIXED_LIST
                        || anAttribute.getAttributeKind() == ClassAttribute.ClassAttributeType.VARIABLE_LIST)
                        && !anAttribute.getUnderlyingTypeIsPrimitive()) {
                   includes.add("#include <" + anAttribute.getType() + ".h>");
                }

                // if this attribute is a variable-length list that holds a class, we need to
                // do an import on the class that is in the list.
                if (anAttribute.getAttributeKind() == ClassAttribute.ClassAttributeType.VARIABLE_LIST) {
                    hasVariableLengthList = true;
                }
            }
            // print collected includes
            for (String include : includes) {
                pw.println(include);
            }