public override bool Reduce(IVariableMap<Expression> Map, ref Expression Reduced)
{
// Is the source tuple an actual tuple?
TupleExpression te = this.SourceTuple as TupleExpression;
if (te != null)
{
// Now we got this :D
Reduced = this.InnerExpression.Substitute(new SimpleMap<Expression>(this.BreakIndex, te.Parts));
return true;
}
// Wouldn't it be hilarious if the inner expression never even used the tuple's data?
Expression cire = this.InnerExpression.Compress(this.BreakIndex, this.TupleSize);
if (cire != null)
{
Reduced = cire;
return true;
}
// Nope, guess i'll have to do it the normal way :(
Expression tre = this.SourceTuple;
Expression ire = this.InnerExpression;
if (tre.Reduce(Map, ref tre) | ire.Reduce(this._CreateInner(Map), ref ire))
{
Reduced = new TupleBreakExpression(this.BreakIndex, this.TupleSize, tre, ire);
return true;
}
return false;
}
public override Expression Substitute(IVariableMap<Expression> Map)
{
return Expression.Lookup(this.Index, Map);
}
public override bool Reduce(IVariableMap<Expression> Map, ref Expression Reduced)
{
// Only possible way to reduce a variable is to replace it with its value.
Expression possible = null;
if (Map.Lookup(this.Index, ref possible))
{
VariableExpression ve = possible as VariableExpression;
if (ve != null)
{
if (ve.Index == this.Index)
{
return false;
}
}
Reduced = possible;
return true;
}
return false;
}
public override Expression Substitute(IVariableMap<Expression> Map)
{
return this;
}
public override Expression Substitute(IVariableMap<Expression> Map)
{
return new FunctionDefineExpression(
this.ArgumentIndex,
this.ArgumentType.Substitute(Map),
this.Function.Substitute(new SubsetMap<Expression>(0, this.ArgumentIndex, Map)));
}
public override Expression Substitute(IVariableMap<Expression> Map)
{
return new FunctionCallExpression(this.Function.Substitute(Map), this.Argument.Substitute(Map));
}
public override bool Reduce(IVariableMap<Expression> Map, ref Expression Reduced)
{
// Beta reduction (substituting an argument in a function definition)
FunctionDefineExpression fde = this.Function as FunctionDefineExpression;
if (fde != null)
{
Reduced = fde.SubstituteCall(this.Argument);
return true;
}
// Recursive reduction
Expression fre = this.Function;
Expression are = this.Argument;
if (fre.Reduce(Map, ref fre) | are.Reduce(Map, ref are))
{
Reduced = new FunctionCallExpression(fre, are);
return true;
}
return false;
}
/// <summary>
/// Substitutes all variables in the expression with their corresponding expression in the specified map. This guarntees all variables in the stack's range
/// to be removed (If all variables only reference variables below them in stack).
/// </summary>
public virtual Expression Substitute(IVariableMap<Expression> Map)
{
return this;
}
/// <summary>
/// Tries to gradually simplifies the expression. Can possibly access the map to dereference a variable.
/// </summary>
public virtual bool Reduce(IVariableMap<Expression> Map, ref Expression Reduced)
{
return false;
}
/// <summary>
/// Looks up or "dereferences" a variable with the given index in the specified stack.
/// </summary>
public static Expression Lookup(int Index, IVariableMap<Expression> Map)
{
Expression res = null;
if (Map.Lookup(Index, ref res))
{
return res.Substitute(Map);
}
else
{
return Expression.Variable(Index);
}
}
public override Expression Substitute(IVariableMap<Expression> Map)
{
if (this.Parts != null)
{
Expression[] subs = new Expression[this.Parts.Length];
for (int t = 0; t < this.Parts.Length; t++)
{
subs[t] = this.Parts[t].Substitute(Map);
}
return new TupleExpression(subs);
}
else
{
return Empty;
}
}
private IVariableMap<Expression> _CreateInner(IVariableMap<Expression> Source)
{
Expression[] stackappend = new Expression[this.TupleSize];
for (int t = 0; t < stackappend.Length; t++)
{
stackappend[t] = Expression.Variable(this.BreakIndex + t);
}
return new SwitchMap<Expression>(
this.BreakIndex,
Source,
new SimpleMap<Expression>(this.BreakIndex, stackappend));
}
public override Expression Substitute(IVariableMap<Expression> Map)
{
return new TupleBreakExpression(
this.BreakIndex,
this.TupleSize,
this.SourceTuple.Substitute(Map),
this.InnerExpression.Substitute(this._CreateInner(Map)));
}
