blog dds: 2006.09.21 - UML Class Diagrams from C++ Code

2006.09.21

UML Class Diagrams from C++ Code

I needed a UML class diagram of the classes I use in the implementation of CScout refactoring browser. I drew the last such diagram on paper about four years ago, so it was definitely out of date. I always say that whenever possible documentation should be automatically generated from the code, so I decided to automate the task.

An appropriate tool for this job is UMLGraph. Unfortunately for the task at hand, its input is following the Java syntax. Getting the appropriate data from the C++ code, didn't require more than 10 minutes of work. In this particular C++ code I only used single inheritance, and the subclass and superclass always appeared on the same line. Taking advantage of these two facts I could simply locate the lines containing public :, and convert them into a corresponding Java class definition. Thus

class Mysql: public Sql {
	// ...
}

would become

class Mysql extends Sql {}

The following pipeline was enough to take inheritance specifications from the C++ code and transform them into UMLGraph's Java syntax.

grep -h ":.*public" *.h |
sed 's/class //;s/://;s/public //;s/{//;s/  */ /g' |
awk '{print "class " $1 " extends " $2 " {}"}'

Here is a part of the final result.
UML class diagram

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