protected virtual void EmitBetweenExpression(BetweenExpression expression)
{
Append("(");
EmitExpression(expression.Expression);
Append(" between ");
EmitExpression(expression.LowerExpression);
Append(" and ");
EmitExpression(expression.UpperExpression);
Append(")");
}
public object Translate(TranslationContext context, ASTNode node)
{
// In(element, interval)...
// In(element, list)
// Translate as:
// exists (select * from (<list>) T where <element equality condition>)
// As long as this is list containment, it can be translated using an Exists(Filter(Collection, Condition(Current = Element)));
var elementNode = node.Children[0];
var collectionNode = node.Children[1];
if (elementNode.ResultType is ListType)
{
throw new NotSupportedException("In translation with an element of type list is not supported because there is no equivalent SQL representation.");
}
if (collectionNode.ResultType is ListType)
{
var selectExpression = new SQLModel.SelectExpression();
selectExpression.SelectClause = new SQLModel.SelectClause();
selectExpression.SelectClause.NonProject = true;
selectExpression.FromClause = new SQLModel.CalculusFromClause(new SQLModel.TableSpecifier(SQLTranslationUtilities.EnsureSelectStatementExpression(context.TranslateNode(collectionNode)), "T"));
selectExpression.WhereClause = new SQLModel.WhereClause();
Model.Expression condition = null;
if (elementNode.ResultType is ObjectType)
{
foreach (var property in ((ObjectType)elementNode.ResultType).Properties)
{
// TODO: O is an assumed alias here, need a way to establish the outer context for comparison of the element....
var propertyCondition = new Model.BinaryExpression(new SQLModel.QualifiedFieldExpression(property.Name, "T"), "iEqual", new SQLModel.QualifiedFieldExpression(property.Name, "O"));
if (condition == null)
{
condition = propertyCondition;
}
else
{
condition = new Model.BinaryExpression(condition, "iAnd", propertyCondition);
}
}
}
else
{
condition = new Model.BinaryExpression(new SQLModel.QualifiedFieldExpression("value", "T"), "iEqual", (Model.Expression)context.TranslateNode(elementNode));
}
selectExpression.WhereClause.Expression = condition;
return selectExpression;
}
else
{
var betweenExpression = new Model.BetweenExpression();
betweenExpression.Expression = (Model.Expression)context.TranslateNode(elementNode);
// TODO: Translate an interval selector....
betweenExpression.LowerExpression = new Model.ValueExpression(1);
betweenExpression.UpperExpression = new Model.ValueExpression(1);
return betweenExpression;
}
}
public object Translate(TranslationContext context, ASTNode node)
{
var requestListType = node.ResultType as ListType;
var requestType = (requestListType == null ? node.ResultType : requestListType.ElementType) as ObjectType;
if (requestType == null)
{
throw new InvalidOperationException(String.Format("Unable to determine request type from source type: '{0}'.", node.ResultType.Name));
}
Model.Expression condition = null;
// Translate Codes
var codes = node.Children.Where(n => n.Name == "codes").FirstOrDefault();
if (codes != null)
{
var codesResult = context.TranslateNode(codes);
// codesResult will be a select statement returning the list of codes
// So the retrieve must include a where condition limiting the code property to the set of codes (same as InValueSet translation)
var codeExpression = SQLTranslationUtilities.ResolvePath(node.GetAttribute<string>("codeProperty"), "T");
var selectExpression = (SQLModel.SelectExpression)codesResult; // This assumes the codes element is a ValueSetRef...
selectExpression.WhereClause.Expression =
new Model.BinaryExpression
(
selectExpression.WhereClause.Expression,
"iAnd",
new Model.BinaryExpression(codeExpression, "iEqual", new SQLModel.QualifiedFieldExpression("Code", "VS"))
);
var codeCondition = new Model.UnaryExpression("iExists", selectExpression);
if (condition != null)
{
condition = new Model.BinaryExpression(condition, "iAnd", codeCondition);
}
else
{
condition = codeCondition;
}
}
// Translate DateRange
var dateRange = node.Children.Where(n => n.Name == "dateRange").FirstOrDefault();
if (dateRange != null)
{
var dateRangeResult = context.TranslateNode(dateRange);
var dateExpression = SQLTranslationUtilities.ResolvePath(node.GetAttribute<string>("dateProperty"), "T");
// dateRangeResult will be an interval-valued expression
// So the retrieve must include a where condition limiting the date range property to the interval (same as In(date, interval) translation)
var dateRangeCondition = new Model.BetweenExpression();
dateRangeCondition.Expression = dateExpression;
// TODO:
//dateRangeCondition.LowerExpression = // dateRangeResult.Low...
//dateRangeCondition.UpperExpression = // dateRangeResult.High...
//if (condition != null)
//{
// condition = new Model.BinaryExpression(condition, "iAnd", dateRangeCondition);
//}
//else
//{
// condition = codeCondition;
//}
}
// For FHIR, there will also potentially need to be profile filters...
// This depends on how the FHIR model is realized within the SQL structures...
var inQueryContext = ((SQLTranslationContext)context).InQueryContext();
// Within a Query Context, a retrieve is part of a FromClause
var tableExpression = new SQLModel.TableExpression(requestType.Name);
if (inQueryContext && (condition == null))
{
return tableExpression;
}
else
{
var selectExpression = new SQLModel.SelectExpression();
selectExpression.SelectClause = new SQLModel.SelectClause();
selectExpression.SelectClause.Distinct = false;
selectExpression.SelectClause.NonProject = true;
selectExpression.FromClause = new SQLModel.CalculusFromClause(new SQLModel.TableSpecifier(tableExpression, "T"));
if (condition != null)
{
selectExpression.WhereClause = new SQLModel.WhereClause();
selectExpression.WhereClause.Expression = condition;
}
return selectExpression;
}
}