/// <summary>
/// Internal expression resolver.
/// </summary>
/// <param name="expr"></param>
/// <param name="ce"></param>
/// <param name="cc"></param>
/// <param name="container"></param>
/// <returns></returns>
/// <remarks>
/// Cache and do cache lookup of expressions to try to short-circuit the expression resolution.
/// </remarks>
public static IValue InternalGetExpression(Expression expr, IGeneratedQueryCode ce, ICodeContext cc, CompositionContainer container)
{
// If we are looking at a null expression, then we resolve to a null value
if (expr == null)
{
return(null);
}
// If this is a known sub-expression, then we should return
// the cached value.
if (ce != null)
{
var v = ce.LookupSubexpression(expr);
if (v != null)
{
return(v);
}
}
// We are going to do the visit. Create the resolver we are going to use
// and configure it.
if (cc == null)
{
cc = new CodeContext();
}
var visitor = new ExpressionToCPP(ce, cc);
visitor.MEFContainer = container;
if (container != null)
{
container.SatisfyImportsOnce(visitor);
}
// Do the visit
visitor.Visit(expr);
// Cache the result.
if (ce != null)
{
ce.RememberSubexpression(expr, visitor.Result);
}
return(visitor.Result);
}