public override void GenerateCode(Emit.ILGenerator ilg, ExecutionContext ec)
{
/*
* Check for two things:
* 1) Is it an argument?
* 2) Is it a local variable (or global)
*/
var arg = ec.GetParameter(varName);
if (arg != null)
{
//This is an argument - we need to store it in its index.
ilg.Emit(Emit.OpCodes.Starg, arg.Position);
return;
}
var varDec = ec.GetVariable(varName);
if (varDec == null)
{
//The person wants this to be a local variable. It has not been declared, so we must do it for them.
varDec = ilg.DeclareLocal(e.GetEvaluatedType(ec));
ec.AddVariable(varName, varDec);
}
e.Push(ilg, ec);
ilg.Emit(Emit.OpCodes.Stloc, varDec); //Store the result of the expression.
}
public override void Push(Emit.ILGenerator ilg, ExecutionContext ec)
{
/*
* Check for three things:
* 1) Is it an argument?
* 2) Is it a local variable (or global)
* 3) Is it a function call without parantheses?
*/
var arg = ec.GetParameter(name);
if (arg != null)
{
//This is an argument - push its index onto the stack!
ilg.Emit(Emit.OpCodes.Ldarg, arg.Position);
return;
}
var varDec = ec.GetVariable(name);
if (varDec != null)
{
//This is a local variable! Push it onto the stack.
ilg.Emit(Emit.OpCodes.Ldloc, varDec);
return;
}
var funcDec = Function.Get(name);
if (funcDec != null)
{
if (funcDec.MethodInfo.ReturnType != typeof(void))
{
ilg.Emit(Emit.OpCodes.Call, funcDec.MethodInfo); //Only functions without parameters can be called currently - changes to the grammar are needed to improve on this and will likely become their own type of expression
return;
}
else
{
throw new Exception("Attempting to use a void type as an expression.");
}
}
//At this point, we have an unrecognized identifier
throw new Exception("Use of undeclared identifier in expression.");
}
public override Type GetEvaluatedType(ExecutionContext ec)
{
var arg = ec.GetParameter(name);
if (arg != null)
{
return arg.Type;
}
var varDec = ec.GetVariable(name);
if (varDec != null)
{
return varDec.LocalType;
}
var funcDec = Function.Get(name);
if (funcDec != null)
{
return funcDec.MethodInfo.ReturnType;
}
//At this point, we have an unrecognized identifier
throw new Exception("Use of undeclared identifier in expression.");
}
