The input scanner can be trapped in an infinite loop if the given input
file does not have EOF (and is not ended with a 'whitespace').
The problem is caused by unget(), which keeps rolling back the scanner
pointer without hitting an EOF at the end of the file. This makes getch()
function keep returning the last character of the file and never ends,
and the effect of advance() is always counteracted by unget().
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.
