Qt 4.4: C++ Source Code Analyzer Example

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# C++ Source Code Analyzer Example

Files:

- xmlpatterns/xquery/globalVariables/globals.cpp
- xmlpatterns/xquery/globalVariables/reportGlobals.xq
- xmlpatterns/xquery/globalVariables/globalVariables.pro

The C++ source code analyzer example shows how to write a real world XQuery query.

## Overview

Sometimes it is of use to analyze C++ code, in order to find common mistakes & patterns. For that one can use search & text utilites like `grep` on UNIX, or try to write ones own C++ parser and subsequently do search there.

But what if there were a simpler but still as correct approach?

g++, the open source C++ compiler, has an extension called GCC-XML that outputs the declarations in a compilation unit(a C++ file) in XML. Since that "C++ to XML" conversion is done with GCC itself, it means the parsing of the C++ code is done with one of the best C++ parsers on this planet.

Once the C++ is in XML, a query can swiftly navigate it to produce a report.

## Global variables

Usually one wants to avoid global mutable variables in C++, since they have a state globally and therefore often is a source to bugs, especially related to threading.

For instance, in globals.cpp, the global, mutable integers as well as the global class instances should preferrably be avoided:

     int mutablePrimitive1;
     int mutablePrimitive2;
     const int constPrimitive1 = 4;
     const int constPrimitive2 = 3;

     class ComplexClass
     {
     public:
         ComplexClass();
         ComplexClass(const ComplexClass &);
         ~ComplexClass();
     };

     ComplexClass mutableComplex1;
     ComplexClass mutableComplex2;
     const ComplexClass constComplex1;
     const ComplexClass constComplex2;

     int main()
     {
         int localVariable;
         localVariable = 0;
         return localVariable;
     }