This patch introduces a new extension, GL_GOOGLE_include_directive,
to enable support #include directives. It depends on the extension
GL_GOOGLE_cpp_style_line_directive.
When an include directive is recognized by the preprocessor, it
executes a callback on the filepath argument to obtain the file
contents. That way the compilation client can deal with the file
system, include paths, etc.
Currently only accepts quoted filepaths -- no angle brackets yet.
According to the GLSL spec, the second parameter to #line should be
an integer source string number and __FILE__ will be substituted
with the integer source string number currently processed. This
patch extends the syntax of #line and __FILE__. Now #line accepts
as the second parameter a filename string quoted by double quotation
marks. And if such a #line is set, __FILE__ will be substituted with
the currently set filename string. The implementation is done via
introducing a new extension GL_GOOGLE_cpp_style_line_directive using
the extension framework.
The purpose is to support cpp-style #line directives, which is
required by #include.
The line argument passed into the lineCallback function is the
literal value of the first argument of the #line directive.
lastLine in DoPreprocessing() should be updated taking into
consideration the different definitions for #line between specs.
Add a test to reveal the bug.
