/// <summary>
/// Generate the code that we will use to access this array. Loop symantics in this framework are basically "foreach" rather than "for" - so
/// we return an object that can be used to reference each array element.
/// </summary>
/// <param name="env"></param>
/// <param name="context"></param>
/// <param name="indexName"></param>
/// <param name="popVariableContext"></param>
/// <returns></returns>
public Tuple <Expression, IDeclaredParameter> AddLoop(IGeneratedQueryCode env, ICodeContext context, CompositionContainer container)
{
///
/// First, we will need to know the length of this array
///
var lenExpression = Expression.ArrayLength(_arrayExpression);
var lenTranslation = ExpressionToCPP.GetExpression(lenExpression, env, context, container);
///
/// Next, generate the expression that forms the basis of the index lookup. We don't
/// translate this - that only gets to happen when one is actually looking at a final result.
///
var loopVariable = DeclarableParameter.CreateDeclarableParameterExpression(typeof(int));
var indexExpression = Expression.MakeBinary(ExpressionType.ArrayIndex, _arrayExpression, loopVariable);
///
/// Now the for loop statement!
///
env.Add(new StatementForLoop(loopVariable, lenTranslation));
///
/// Return the index expression - the thing that can be used to replace all expressions and
/// reference the item we are looping over.
///
return(Tuple.Create <Expression, IDeclaredParameter>(indexExpression, loopVariable));
}
/// <summary>
/// We have an enumerable range expression. Process it! :-)
/// </summary>
/// <param name="expr"></param>
/// <param name="gc"></param>
/// <param name="cc"></param>
/// <param name="container"></param>
/// <param name="ReGetIArrayInfo"></param>
/// <returns></returns>
private IArrayInfo ProcessEnumerableRangeExpression(Expression expr, IGeneratedQueryCode gc, ICodeContext cc, CompositionContainer container, Func <Expression, IArrayInfo> ReGetIArrayInfo)
{
var er = expr as EnumerableRangeExpression;
var minVal = ExpressionToCPP.GetExpression(er.LowBoundary, gc, cc, container);
var maxVal = ExpressionToCPP.GetExpression(er.HighBoundary, gc, cc, container);
return(new EnumerableRangeArrayInfo(minVal, maxVal));
}
/// <summary>
/// We only support a sub-class of expressions for now - so we'd better make sure we are protected!
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected override Expression VisitConditional(ConditionalExpression expression)
{
// We can support complex sub-expressions so long as they don't leak out of the
// comparison.
if (expression.Type.IsClass &&
(
CheckForSubQueries.CheckExpression(expression.IfFalse) ||
CheckForSubQueries.CheckExpression(expression.IfTrue))
)
{
throw new NotSupportedException(string.Format("Complex true/false clauses in a conditional expression are not supported: '{0}'", expression.ToString()));
}
// If this is a class as a result, then we can't do much extra processing here. So skip.
if (expression.Type.IsClass)
{
return(base.VisitConditional(expression));
}
// Run the code for the test, and then create the if/then/else that will support it.
var testExpression = base.Visit(expression.Test);
var testExpressionEvaluation = ExpressionToCPP.GetExpression(testExpression, GeneratedCode, CodeContext, MEFContainer);
var testBoolInCode = testExpressionEvaluation is DeclarableParameter p ? p : DeclarableParameter.CreateDeclarableParameterExpression(typeof(bool));
if (testBoolInCode != testExpressionEvaluation)
{
GeneratedCode.Add(testBoolInCode);
GeneratedCode.Add(new Statements.StatementAssign(testBoolInCode, testExpressionEvaluation));
}
// The result
var conditionalResult = DeclarableParameter.CreateDeclarableParameterExpression(expression.Type);
GeneratedCode.Add(conditionalResult);
// Do the if true statement
var topScope = GeneratedCode.CurrentScope;
GeneratedCode.Add(new Statements.StatementFilter(testBoolInCode));
var iftrueExpression = Visit(expression.IfTrue);
GeneratedCode.Add(new Statements.StatementAssign(conditionalResult, ExpressionToCPP.GetExpression(iftrueExpression, GeneratedCode, CodeContext, MEFContainer)));
GeneratedCode.CurrentScope = topScope;
// Do the if false statement
GeneratedCode.Add(new Statements.StatementFilter(ExpressionToCPP.GetExpression(Expression.Not(testBoolInCode), GeneratedCode, CodeContext, MEFContainer)));
var ifFalseExpression = Visit(expression.IfFalse);
GeneratedCode.Add(new Statements.StatementAssign(conditionalResult, ExpressionToCPP.GetExpression(ifFalseExpression, GeneratedCode, CodeContext, MEFContainer)));
GeneratedCode.CurrentScope = topScope;
// Consider this expression now transformed, so return the result, not
// the conditional expression itself.
return(conditionalResult);
}
/// <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);
}
