private static SwitchExpression CompileState <OutputT>(TransducerState <Char, OutputT> state, ParameterExpression reader, ParameterExpression output, LabelTarget @return, Int32 depth)
{
var idx = 0;
var cases = new SwitchCase[state.TransitionTable.Count];
foreach (KeyValuePair <Char, TransducerState <Char, OutputT> > statePair in state.TransitionTable)
{
cases[idx++] = Expression.SwitchCase(
CompileState(statePair.Value, reader, output, @return, depth + 1),
Expression.Constant((Char?)statePair.Key)
);
}
return(Expression.Switch(
GExpression.MethodCall <ICodeReader>(reader, r => r.Peek(depth), depth),
state.IsTerminal
? Expression.Block(
GExpression.MethodCall <ICodeReader>(reader, r => r.Advance(0), depth + 1),
Expression.Assign(output, Expression.Constant(state.Output)),
Expression.Return(@return, Expression.Constant(true))
)
: (Expression)Expression.Return(@return, Expression.Constant(false)),
cases
));
}
private static SwitchExpression CompileState <TTokenType, OutputT>(TransducerState <Token <TTokenType>, OutputT> state, ParameterExpression reader, ParameterExpression output, LabelTarget @return, Int32 depth)
where TTokenType : notnull
{
var idx = 0;
var cases = new SwitchCase[state.TransitionTable.Count];
foreach (KeyValuePair <Token <TTokenType>, TransducerState <Token <TTokenType>, OutputT> > statePair in state.TransitionTable)
{
cases[idx++] = Expression.SwitchCase(
CompileState(statePair.Value, reader, output, @return, depth + 1),
Expression.Constant(statePair.Key)
);
}
return(Expression.Switch(
GExpression.MethodCall <ITokenReader <TTokenType> >(reader, r => r.Lookahead(depth), depth),
state.IsTerminal
? Expression.Block(
GExpression.MethodCall <ITokenReader <TTokenType> >(reader, r => r.Skip(0), depth + 1),
Expression.Assign(output, Expression.Constant(state.Output)),
Expression.Return(@return, Expression.Constant(true))
)
: (Expression)Expression.Constant(false),
cases
));
}
