EmitByteArg() private method

private EmitByteArg ( Instruction instruction, int arg ) : int
instruction Instruction
arg int
return int
Esempio n. 1
0
        private static void Field(Compiler c, bool allowAssignment)
        {
            // Initialize it with a fake value so we can keep parsing and minimize the
            // number of cascaded errors.
            int field = 255;

            ClassCompiler enclosingClass = c.GetEnclosingClass();

            if (enclosingClass == null)
            {
                c.Error("Cannot reference a field outside of a class definition.");
            }
            else if (enclosingClass.IsStaticMethod)
            {
                c.Error("Cannot use an instance field in a static method.");
            }
            else
            {
                // Look up the field, or implicitly define it.
                string fieldName = c._parser.Source.Substring(c._parser.Previous.Start, c._parser.Previous.Length);
                field = enclosingClass.Fields.IndexOf(fieldName);
                if (field < 0)
                {
                    enclosingClass.Fields.Add(fieldName);
                    field = enclosingClass.Fields.IndexOf(fieldName);
                }

                if (field >= MaxFields)
                {
                    c.Error(string.Format("A class can only have {0} fields.", MaxFields));
                }
            }

            // If there's an "=" after a field name, it's an assignment.
            bool isLoad = true;
            if (c.Match(TokenType.Eq))
            {
                if (!allowAssignment) c.Error("Invalid assignment.");

                // Compile the right-hand side.
                c.Expression();
                isLoad = false;
            }

            // If we're directly inside a method, use a more optimal instruction.
            if (c._parent != null && c._parent._enclosingClass == enclosingClass)
            {
                c.EmitByteArg(isLoad ? Instruction.LOAD_FIELD_THIS : Instruction.STORE_FIELD_THIS,
                            field);
            }
            else
            {
                c.LoadThis();
                c.EmitByteArg(isLoad ? Instruction.LOAD_FIELD : Instruction.STORE_FIELD, field);
            }
        }