// <summary>
// Collapses outerProject(outerProjection(innerProject(innerNew)))
// </summary>
private static DbExpression CollapseNestedProjection(DbExpression expression)
{
var outerProject = (DbProjectExpression)expression;
var outerProjection = outerProject.Projection;
var innerProject = (DbProjectExpression)outerProject.Input.Expression;
var innerNew = (DbNewInstanceExpression)innerProject.Projection;
// get membername -> expression bindings for the inner select so that we know how map property
// references to the inner projection
var bindings = new Dictionary <string, DbExpression>(innerNew.Arguments.Count);
var innerResultTypeUsage = innerNew.ResultType;
var innerResultType = (RowType)innerResultTypeUsage.EdmType;
for (var ordinal = 0; ordinal < innerResultType.Members.Count; ordinal++)
{
bindings[innerResultType.Members[ordinal].Name] = innerNew.Arguments[ordinal];
}
// initialize an expression visitor that knows how to map arguments to the outer projection
// to the inner projection source
var collapser = new ProjectionCollapser(bindings, outerProject.Input);
// replace all property references to the inner projection
var replacementOuterProjection = collapser.CollapseProjection(outerProjection);
// make sure the collapsing was successful; if not, give up on simplification
if (collapser.IsDoomed)
{
return(null);
}
// set replacement value so that the expression replacer infrastructure can substitute
// the collapsed projection in the expression tree
// continue collapsing projection until the pattern no longer matches
var replacementOuterProject = innerProject.Input.Project(replacementOuterProjection);
return(replacementOuterProject);
}
/// <summary>
/// Collapses outerProject(outerProjection(innerProject(innerNew)))
/// </summary>
private static DbExpression CollapseNestedProjection(DbExpression expression)
{
DbProjectExpression outerProject = (DbProjectExpression)expression;
DbExpression outerProjection = outerProject.Projection;
DbProjectExpression innerProject = (DbProjectExpression)outerProject.Input.Expression;
DbNewInstanceExpression innerNew = (DbNewInstanceExpression)innerProject.Projection;
// get membername -> expression bindings for the inner select so that we know how map property
// references to the inner projection
Dictionary<string, DbExpression> bindings = new Dictionary<string, DbExpression>(innerNew.Arguments.Count);
TypeUsage innerResultTypeUsage = innerNew.ResultType;
RowType innerResultType = (RowType)innerResultTypeUsage.EdmType;
for (int ordinal = 0; ordinal < innerResultType.Members.Count; ordinal++)
{
bindings[innerResultType.Members[ordinal].Name] = innerNew.Arguments[ordinal];
}
// initialize an expression visitor that knows how to map arguments to the outer projection
// to the inner projection source
ProjectionCollapser collapser = new ProjectionCollapser(bindings, outerProject.Input);
// replace all property references to the inner projection
var replacementOuterProjection = collapser.CollapseProjection(outerProjection);
// make sure the collapsing was successful; if not, give up on simplification
if (collapser.IsDoomed) { return null; }
// set replacement value so that the expression replacer infrastructure can substitute
// the collapsed projection in the expression tree
// continue collapsing projection until the pattern no longer matches
DbProjectExpression replacementOuterProject = innerProject.Input.Project(replacementOuterProjection);
return replacementOuterProject;
}
