Method parseDirectives

src/cinder/gl/ShaderPreprocessor.cpp:209–268

- returns directives string and remaining source separately, so that parseTopLevel can start after the directives we've added - lineNumberStart indicates what value a #line directive should have after parsing #include statements

// - returns directives string and remaining source separately, so that parseTopLevel can start after the directives we've added
// - lineNumberStart indicates what value a #line directive should have after parsing #include statements
void ShaderPreprocessor::parseDirectives( const std::string &source, const fs::path &sourcePath, std::string *directives, std::string *sourceBody, int *versionNumber, int *lineNumberStart )
{		
	// go through each line and find the #version directive
	int lineNumber = 1;
	bool hasVersionLine = false;

	for( size_t lineStartPos = 0; lineStartPos < source.size(); /* */ ) {
		size_t lineEndPos = source.find( '\n', lineStartPos );
		if( lineEndPos == std::string::npos )
			break;

		if( findVersionStatement( source.c_str() + lineStartPos, versionNumber ) ) {
			// if no defines, return leaving the directive and sourceBody strings empty,
			// thereby indicating to use the original source without modification;
			if( mDefineDirectives.empty() ) {
				*lineNumberStart = 1;
				return;
			}

			// Copy #version line and everything before it to the directives string, the rest to sourceBody
			*directives = source.substr( 0, lineEndPos + 1 );
			*sourceBody = source.substr( lineEndPos + 1 );
			*lineNumberStart = lineNumber;
			hasVersionLine = true;

			break;
		}

		lineStartPos = lineEndPos + 1;
		lineNumber++;
	}

	// if we don't have a version yet, add a default one that will be at the top
	if( ! hasVersionLine ) {
#if defined( CINDER_GL_ES_3 )
		*directives += "#version " + to_string( mVersion ) + " es\n";
#else
		*directives += "#version " + to_string( mVersion ) + "\n";
#endif

		*sourceBody = source; // sourceBody is the entire source
		*lineNumberStart = 0;
		*versionNumber = mVersion;
	}

	// append any #defines to the directives string
	for( const auto &define : mDefineDirectives ) {
		*directives += "#define " + define.first;
		if( ! define.second.empty() )
			*directives += " " + define.second;

		*directives += "\n";
	}

	// if we've made any modifications, add a #line directive to ensure debug error statements are correct.
	if( ! mDefineDirectives.empty() || ! hasVersionLine ) {
		*directives += getLineDirective( sourcePath, *lineNumberStart, 0, *versionNumber );
		*lineNumberStart += 1;