public static Expression AnalyzeBinaryExpr(SymplBinaryExpr expr,
AnalysisScope scope)
{
// The language has the following special logic to handle And and Or
// x And y == if x then y
// x Or y == if x then x else (if y then y)
if (expr.Operation == ExpressionType.And)
{
return(AnalyzeIfExpr(
new SymplIfExpr(
expr.Left, expr.Right, null),
scope));
}
else if (expr.Operation == ExpressionType.Or)
{
// Use (LetStar (tmp expr) (if tmp tmp)) to represent (if expr expr)
// to remore duplicate evaluation.
// So x Or y is translated into
// (Let* (tmp1 x)
// (If tmp1 tmp1
// (Let* (tmp2 y) (If tmp2 tmp2))))
//
IdOrKeywordToken tmp2 = new IdOrKeywordToken(
// Real implementation needs to ensure unique ID in scope chain.
"__tmpLetVariable2");
var tmpExpr2 = new SymplIdExpr(tmp2);
var binding2 = new LetBinding(tmp2, expr.Right);;
var ifExpr2 = new SymplIfExpr(
tmpExpr2, tmpExpr2, null);
var letExpr2 = new SymplLetStarExpr(
new[] { binding2 },
new[] { ifExpr2 });
IdOrKeywordToken tmp1 = new IdOrKeywordToken(
// Real implementation needs to ensure unique ID in scope chain.
"__tmpLetVariable1");
var tmpExpr1 = new SymplIdExpr(tmp1);
LetBinding binding1 = new LetBinding(tmp1, expr.Left);;
SymplExpr ifExpr1 = new SymplIfExpr(
tmpExpr1, tmpExpr1, letExpr2);
return(AnalyzeLetStarExpr(
new SymplLetStarExpr(
new[] { binding1 },
new[] { ifExpr1 }
),
scope
));
}
return(Expression.Dynamic(
scope.GetRuntime().GetBinaryOperationBinder(expr.Operation),
typeof(object),
AnalyzeExpr(expr.Left, scope),
AnalyzeExpr(expr.Right, scope)
));
}
public static Expression AnalyzeIfExpr(SymplIfExpr expr,
AnalysisScope scope)
{
Expression alt = null;
if (expr.Alternative != null)
{
alt = AnalyzeExpr(expr.Alternative, scope);
}
else
{
alt = Expression.Constant(false);
}
return(Expression.Condition(
WrapBooleanTest(AnalyzeExpr(expr.Test, scope)),
Expression.Convert(AnalyzeExpr(expr.Consequent, scope),
typeof(object)),
Expression.Convert(alt, typeof(object))));
}
