/// <summary>
/// Evaluates a parsed expression using the specified interpreter input.
/// </summary>
public static Datum Evaluate(Parser.Expression ParsedExpression, ProgramInput Input)
{
// Assign all input variables to a position on the stack of the root scope. (Seperates names and values)
IVariableStack<Expression> typestack;
IMutableVariableStack<Value> datastack;
Scope scope;
Input.PrepareRootScope(out scope, out datastack, out typestack);
// Prepare
Expression exp = Expression.Prepare(ParsedExpression, scope, Input);
Expression exptype;
exp.TypeCheck(typestack, SpaghettiStack<Expression>.Empty(typestack.NextFreeIndex), out exp, out exptype);
// Evaluate
return new Datum(exp.Evaluate(datastack), exptype);
}
private static void _PrepareLambda(
List<KeyValuePair<Parser.Expression, string>> Arguments,
Parser.Expression Inner, Scope Scope, ProgramInput Input,
out Expression ArgumentType, out Expression PreparedInner)
{
// 0 arg function
if (Arguments.Count == 0)
{
ArgumentType = TupleExpression.Empty;
PreparedInner = Prepare(Inner, Scope, Input);
return;
}
// 1 arg function
Dictionary<string, int> vars;
int argloc = Scope.NextFreeIndex;
Scope nscope = new Scope()
{
NextFreeIndex = argloc + 1,
Variables = vars = new Dictionary<string, int>(),
Parent = Scope
};
if (Arguments.Count == 1)
{
var kvp = Arguments[0];
if (kvp.Value != null)
{
vars.Add(kvp.Value, argloc);
}
ArgumentType = Prepare(kvp.Key, Scope, Input);
PreparedInner = Prepare(Inner, nscope, Input);
return;
}
// 2+ arg function
Expression[] types = new Expression[Arguments.Count];
for (int t = 0; t < types.Length; t++)
{
types[t] = Prepare(Arguments[t].Key, Scope, Input);
}
nscope.NextFreeIndex += types.Length;
for (int t = 0; t < Arguments.Count; t++)
{
string argname = Arguments[t].Value;
if (argname != null)
{
vars.Add(argname, t + argloc + 1);
}
}
ArgumentType = Expression.Tuple(types);
PreparedInner = Expression.BreakTuple(
argloc + 1,
Arguments.Count,
Expression.Variable(argloc),
Prepare(Inner, nscope, Input));
}
/// <summary>
/// Prepares a parsed expression for use.
/// </summary>
public static Expression Prepare(Parser.Expression Expression, Scope Scope, ProgramInput Input)
{
// Function call
Parser.FunctionCallExpression fce = Expression as Parser.FunctionCallExpression;
if (fce != null)
{
Expression func = Prepare(fce.Function, Scope, Input);
if (fce.Arguments.Count == 0)
{
return new FunctionCallExpression(func, TupleExpression.Empty);
}
if (fce.Arguments.Count == 1)
{
return new FunctionCallExpression(func, Prepare(fce.Arguments[0], Scope, Input));
}
Expression[] args = new Expression[fce.Arguments.Count];
for (int t = 0; t < args.Length; t++)
{
args[t] = Prepare(fce.Arguments[t], Scope, Input);
}
return new FunctionCallExpression(func, new TupleExpression(args));
}
// Procedure
Parser.ProcedureExpression pe = Expression as Parser.ProcedureExpression;
if (pe != null)
{
return ProcedureExpression.Prepare(pe, Scope, Input);
}
// Variable
Parser.VariableExpression ve = Expression as Parser.VariableExpression;
if (ve != null)
{
return PrepareVariable(ve.Name, Scope);
}
// Integer liteal
Parser.IntegerLiteralExpression ile = Expression as Parser.IntegerLiteralExpression;
if (ile != null)
{
return new ValueExpression(Input.GetIntegerLiteral(ile.Value), Input.IntegerLiteralType);
}
// Accessor
Parser.AccessorExpression ae = Expression as Parser.AccessorExpression;
if (ae != null)
{
return new AccessorExpression(Prepare(ae.Object, Scope, Input), ae.Property);
}
// Function definition
Parser.FunctionDefineExpression fde = Expression as Parser.FunctionDefineExpression;
if (fde != null)
{
Expression argtype;
Expression inner;
_PrepareLambda(fde.Arguments, fde.Definition, Scope, Input, out argtype, out inner);
return new FunctionDefineExpression(Scope.NextFreeIndex, argtype, inner);
}
// Function type
Parser.FunctionTypeExpression fte = Expression as Parser.FunctionTypeExpression;
if (fte != null)
{
// Notice that this is almost exactly the same as a function definition? weird type system, eh?
Expression argtype;
Expression inner;
_PrepareLambda(fte.ArgumentTypes, fte.ReturnType, Scope, Input, out argtype, out inner);
return new FunctionDefineExpression(Scope.NextFreeIndex, argtype, inner);
}
throw new NotImplementedException();
}