/// <summary>
/// Compiles state into <see cref="SwitchCase"/> expression.
/// </summary>
/// <param name="context">Context with compilation info.</param>
/// <returns>Compiled state.</returns>
internal SwitchCase Compile(AutomatonBuilderContext context)
{
var stateBody = compileStateBody(context);
stateBody = context.MakeVoid(stateBody);
return Expression.SwitchCase(stateBody, Expression.Constant(Id));
}
internal AutomatonBuilder()
{
_context = new AutomatonBuilderContext();
_rootState = _context.CreateNewState();
_lastTargetState = _rootState;
}
internal Expression BuildParser(AutomatonBuilderContext context)
{
return buildBodyParser(context);
}
private Expression compileStateBody(AutomatonBuilderContext context)
{
if (_director != null)
{
//we can directly compile the action
if (_targetState == null)
//action without target state
return _director(context);
else
return Expression.Block(
_director(context),
context.GoToState(_targetState)
);
}
//compile byte switch table
var byteCases = new List<SwitchCase>();
foreach (var byteTargetPair in _byteTargets)
{
var gotoStateExpression = context.GoToState(byteTargetPair.Value);
var byteTargetCase = Expression.SwitchCase(gotoStateExpression, Expression.Constant(byteTargetPair.Key));
byteCases.Add(byteTargetCase);
}
//compile byte action table
foreach (var byteActionPair in _byteActions)
{
var actionExpression = byteActionPair.Value(context);
var byteActionCase = Expression.SwitchCase(context.MakeVoid(actionExpression), Expression.Constant(byteActionPair.Key));
byteCases.Add(byteActionCase);
}
if (_defaultByteTarget == null)
{
return Expression.Switch(context.InputVariable, byteCases.ToArray());
}
else
{
//we are in state with default target
return Expression.Switch(context.InputVariable, context.GoToState(_defaultByteTarget), byteCases.ToArray());
}
}
/// <summary> /// Template method which builds parser for the header. /// </summary> internal abstract Expression buildBodyParser(AutomatonBuilderContext context);