Add lexing, parsing and some semantic checking for constant buffers.

Parsing.jai

@@ -883,6 +883,26 @@ property_block :: (parse_state : *Parse_State, identifier_token : *Token = null)
 	return node;
 }
 
+constant_buffer :: (parse_state : *Parse_State, identifier_token : *Token = null) -> *AST_Node {
+	node : *AST_Node;
+	source_location : Source_Range;
+	source_location.begin = parse_state.current;
+	consume(parse_state, .TOKEN_LEFTBRACE, "Expect '{' after 'constant_buffer' keyword");
+	buffer := field_list(parse_state, .Semicolon);
+
+	node = make_node(parse_state, .CBuffer);
+	if identifier_token {
+		node.name = identifier_token.ident_value;
+	}
+	add_child(node, buffer);
+
+	consume(parse_state, .TOKEN_RIGHTBRACE, "Expect '}' after 'constant_buffer' block");
+	source_location.end = parse_state.previous;
+	node.source_location = source_location;
+
+	return node;
+}
+
 struct_declaration :: (parse_state : *Parse_State, identifier_token : *Token) -> *AST_Node {
 	source_location := generate_source_location_from_token(parse_state, identifier_token);
 	
@@ -914,6 +934,8 @@ const_declaration :: (parse_state : *Parse_State, identifier_token : *Token) ->
 		return function_declaration(parse_state, identifier_token, .None);
 	} else if match(parse_state, .TOKEN_PROPERTIES) {
 		return property_block(parse_state, identifier_token);
+	} else if match(parse_state, .TOKEN_CONSTANT_BUFFER) {
+		return constant_buffer(parse_state, identifier_token);
 	}
 	return error_node(parse_state, tprint("Couldn't parse constant declaration at token %\n", parse_state.current.*));
 }