QDoc: Move `CodeParser::parseHeaderFile` to `ClangCodeParser`

QDoc parses a series of source file in different languages and formats
to find the user-provided documentation.

The base parsing interface for elements that perform this process is
given by the `CodeParser` class, with the concrete implementation of the
process for different languages/formats give by its child classes.

`CodeParser`, as part of its interface, provides certain methods that
are only meaningful when processing specific programming languages
source.

For example, it exposes `CodeParser::parseHeaderFile` whose purpose it
to provide an entry point for parsing C++ header files.

The method is only meaningfully implemented and used in the
`ClangCodeParser` child class, the class that actually implements the
processing of C++ source files.

Hence, the method is now removed from `CodeParser`'s interface and
directly exposed as part of the interface of `ClangCodeParser`, to
reduce the surface of the method and to reduce the dependencies between
`ClangCodeParser` and the `CodeParser` interface, which is generally
expected to be removed in the future.

`CodeParser` are, currently and temporarily, mostly initialized
statically and then retrieved through certain methods of the
`CodeParser` interface.
`CodeParser::parserForHeaderFile` is one such method that would retrieve
a `CodeParser` or child class instance that is able to parse an header
file.

Due to the removal of `parseHeaderFile` from `CodeParser` interface and
the fact that only one specific parser is able, and should be able, to
parse header files, `CodeParser::parserForHeaderFile` was removed.

Its only usage in "main.cpp", where it was called to retrieve the
already available `ClangCodeParser`, was modified to make use of
`ClangCodeParser` directly.

An auxiliary method, `CodeParser::headerFileNameFilter`, previously used
only by `CodeParser::parserForHeaderFile`, which provided a list of
extensions to identify what files could be accepted by a certain parser
as header files, is now removed as dead code.
A non-meaningful reimplementation of the `headerFileNameFilter` method
in `CppCodeParser`, a child class of `CodeParser`, was removed as of
consequence.

Similarly, the same method implementation in `ClangCodeParser` was
removed.
The filtering functionality that the method indirectly provided when
used by `CodeParser::parserForHeaderFile`, which is to be retained for
backward compatibility reasons, was moved to
`processQdocconfFile` in "main.cpp", where the header files that should
be parsed are gathered.
Instead of using the `headerFileNameFilter` method, the data that was
provided by it is now exposed as a static member of `ClangCodeParser`
and accessed directly when filtering is necessary.

Change-Id: Iff9a204627675aa7b34232c114945afceb8313ff
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

1 files changed, 4 insertions, 13 deletions

diff --git a/src/qdoc/clangcodeparser.cpp b/src/qdoc/clangcodeparser.cpp
index d2338ee32..e3984e502 100644
--- a/src/qdoc/clangcodeparser.cpp
+++ b/src/qdoc/clangcodeparser.cpp
@@ -41,6 +41,10 @@
 
 QT_BEGIN_NAMESPACE
 
+const QStringList ClangCodeParser::accepted_header_file_extensions{
+    "ch", "h", "h++", "hh", "hpp", "hxx"
+};
+
 // We're printing diagnostics in ClangCodeParser::printDiagnostics,
 // so avoid clang itself printing them.
 static const auto kClangDontDisplayDiagnostics = 0;
@@ -1240,19 +1244,6 @@ QString ClangCodeParser::language()
 }
 
 /*!
-  Returns a list of extensions for header files.
- */
-QStringList ClangCodeParser::headerFileNameFilter()
-{
-    return QStringList() << "*.ch"
-                         << "*.h"
-                         << "*.h++"
-                         << "*.hh"
-                         << "*.hpp"
-                         << "*.hxx";
-}
-
-/*!
   Returns a list of extensions for source files, i.e. not
   header files.
  */