/// <name>EndBlock</name>
/// <type>Method</type>
/// <summary>
/// End block code generator.
/// </summary>
private void EndBlock()
{
Structure s = structureStack.Pop();
if (s.Type == StructType.ELSE_STRUCT && nextOperator.Lexeme == "endif")
{
// End of an else block
FillAddress(s.JumpLocation, jvm.ProgramCounter);
}
else if (s.Type == StructType.IF_STRUCT && nextOperator.Lexeme == "else")
{
// End of an if block but start of else block
Structure elseStruct = new Structure(StructType.ELSE_STRUCT);
elseStruct.JumpLocation = jvm.ProgramCounter;
jvm.Emit(Opcode.GOTO, 0);
structureStack.Push(elseStruct);
FillAddress(s.JumpLocation, jvm.ProgramCounter);
}
else if (s.Type == StructType.IF_STRUCT && nextOperator.Lexeme == "endif")
{
// End of an if block with no else block
FillAddress(s.JumpLocation, jvm.ProgramCounter);
}
else if (s.Type == StructType.WHILE_STRUCT && nextOperator.Lexeme == "endwhile")
{
// End of a while block
jvm.Emit(Opcode.GOTO, s.ConditionLocation - jvm.ProgramCounter);
FillAddress(s.JumpLocation, jvm.ProgramCounter);
}
else if (s.Type == StructType.PROC_STRUCT && nextOperator.Lexeme == "endproc")
{
// End of a procedure
jvm.Emit(Opcode.ASTORE_0);
jvm.Emit(Opcode.RET, (byte)0);
symbolTable["$MAIN"].Address = jvm.ProgramCounter;
}
else if (s.Type == StructType.PROGRAM_STRUCT && nextOperator.Lexeme == "endprogram")
{
// End of the program
jvm.Emit(Opcode.RETURN);
status = Status.EXIT;
}
else
{
Compiler.ThrowCompilerException("Structure type does not match control block");
}
}
/// <name>BeginCondition</name>
/// <type>Method</type>
/// <summary>
/// Begin condition code generator.
/// </summary>
private void BeginCondition()
{
if (nextOperator.Lexeme == "if")
{
// Start of if block, push the new structure onto the stack
Structure ifStruct = new Structure(StructType.IF_STRUCT);
ifStruct.ConditionLocation = jvm.ProgramCounter;
Advance();
// Handle the conditional part of the statement
CompileCondition();
// Now set the return location to the beginning of the branch
ifStruct.JumpLocation = jvm.ProgramCounter - 3;
structureStack.Push(ifStruct);
}
else
{
// Start of while block, push the new structure onto the stack
Structure whileStruct = new Structure(StructType.WHILE_STRUCT);
whileStruct.ConditionLocation = jvm.ProgramCounter;
Advance();
// Handle the conditional part of the statement
CompileCondition();
// Now set the return location to the beginning of the branch
whileStruct.JumpLocation = jvm.ProgramCounter - 3;
structureStack.Push(whileStruct);
}
}