[C++] Rewrite of the preprocessor.

This rewrite fixes a couple of issues with the pre-processor. It now
supports:
- macros in macro bodies
- stringification of parameters [cpp.stringize]
- the concatenation operator [cpp.concat]
- #include MACRO_HERE
- defined() inside macro bodies used in pp-conditions.

Change-Id: Ifdb78041fb6afadf44f939a4bd66ce2832b8601f
Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

src/libs/cplusplus/PreprocessorEnvironment.cpp

@@ -150,7 +150,7 @@ void Environment::reset()
     _hash_count = 401;
 }
 
-bool Environment::isBuiltinMacro(const QByteArray &s)
+bool Environment::isBuiltinMacro(const Internal::ByteArrayRef &s)
 {
     if (s.length() != 8)
         return false;
@@ -236,6 +236,22 @@ Macro *Environment::resolve(const QByteArray &name) const
     return it;
 }
 
+Macro *Environment::resolve(const Internal::ByteArrayRef &name) const
+{
+    if (! _macros)
+        return 0;
+
+    Macro *it = _hash[hashCode(name) % _hash_count];
+    for (; it; it = it->_next) {
+        if (it->name() != name)
+            continue;
+        else if (it->isHidden())
+            return 0;
+        else break;
+    }
+    return it;
+}
+
 unsigned Environment::hashCode(const QByteArray &s)
 {
     unsigned hash_value = 0;
@@ -246,6 +262,16 @@ unsigned Environment::hashCode(const QByteArray &s)
     return hash_value;
 }
 
+unsigned Environment::hashCode(const Internal::ByteArrayRef &s)
+{
+    unsigned hash_value = 0;
+
+    for (int i = 0; i < s.length(); ++i)
+        hash_value = (hash_value << 5) - hash_value + s.at(i);
+
+    return hash_value;
+}
+
 void Environment::rehash()
 {
     if (_hash) {