/// <summary>
/// Visits a let expression
/// </summary>
/// <param name="letExpression"></param>
protected virtual void VisitLetExpression(LetExpression letExpression)
{
if (letExpression.BindingExpression != null)
{
VisitExpression(letExpression.BindingExpression);
}
if (letExpression.Expression != null)
{
VisitExpression(letExpression.Expression);
}
}
/// <summary>
/// Visits a let expression
/// </summary>
/// <param name="letExpression"></param>
protected virtual void VisitLetExpression(LetExpression letExpression)
{
if (letExpression.BindingExpression != null)
{
VisitExpression(letExpression.BindingExpression);
}
if (letExpression.Expression != null)
{
VisitExpression(letExpression.Expression);
}
}
/// <summary>
/// Provides the parse tree associated to the expression stored in the buffer
/// </summary>
/// <param name="expressionLevel">the current level of the expression</param>
/// <returns></returns>
private Expression Expression(int expressionLevel)
{
Expression retVal = null;
if (expressionLevel == 0 && LookAhead("LET"))
{
int start = Index;
Match("LET");
string boundVariable = Identifier();
string assignOp = LookAhead(AssignOps);
if (assignOp != null)
{
Match(assignOp);
Expression bindinExpression = Expression(0);
if (bindinExpression != null)
{
Match("IN");
Expression expression = Expression(0);
if (expression != null)
{
retVal = new LetExpression(Root, RootLog, boundVariable, bindinExpression, expression, start,
Index);
}
else
{
RootLog.AddError("Cannot parse expression after IN keyword");
}
}
else
{
RootLog.AddError("Cannot parse expression after " + boundVariable + " " + assignOp + " ");
}
}
else
{
RootLog.AddError("<- or => expected after " + boundVariable);
}
}
else
{
switch (expressionLevel)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
//
// Binary expressions
//
retVal = Expression(expressionLevel + 1);
if (retVal != null)
{
retVal = ExpressionContinuation(expressionLevel, retVal);
}
break;
case 6:
// Continuation, either by . operator, or by function call
retVal = Continuation(Expression(expressionLevel + 1));
break;
case 7:
//
// List operations
//
retVal = EvaluateListExpression();
if (retVal == null)
{
//
// Unary expressions
//
retVal = EvaluateUnaryExpression();
}
break;
}
}
return retVal;
}
/// <summary>
/// Visits a let expression
/// </summary>
/// <param name="letExpression"></param>
protected virtual void VisitLetExpression(LetExpression letExpression)
{
if (letExpression.BindingExpression != null)
{
VisitInterpreterTreeNode(letExpression.BindingExpression);
}
if (letExpression.Expression != null)
{
VisitInterpreterTreeNode(letExpression.Expression);
}
}