private LambdaExpression Parameterize(Expression query, out object[] arguments) { IQueryProvider provider = this.FindProvider(query); if (provider == null) { throw new ArgumentException("Cannot deduce query provider from query"); } var ep = provider as IEntityProvider; Func <Expression, bool> fn = ep != null ? (Func <Expression, bool>)ep.CanBeEvaluatedLocally : null; List <ParameterExpression> parameters = new List <ParameterExpression>(); List <object> values = new List <object>(); var body = PartialEvaluator.Eval(query, fn, c => { bool isQueryRoot = c.Value is IQueryable; if (!isQueryRoot && ep != null && !ep.CanBeParameter(c)) { return(c); } var p = Expression.Parameter(c.Type, "p" + parameters.Count); parameters.Add(p); values.Add(c.Value); // if query root then parameterize but don't replace in the tree if (isQueryRoot) { return(c); } return(p); }); if (body.Type != typeof(object)) { body = Expression.Convert(body, typeof(object)); } arguments = values.ToArray(); if (arguments.Length < 5) { return(Expression.Lambda(body, parameters.ToArray())); } else { arguments = new object[] { arguments }; return(ExplicitToObjectArray.Rewrite(body, parameters)); } }
internal IQueryProvider FindProvider(Expression expression, object[] args) { Expression root = this.FindProviderInExpression(expression) as ConstantExpression; if (root == null && args != null && args.Length > 0) { Expression replaced = ExpressionReplacer.ReplaceAll( expression, this.query.Parameters.ToArray(), args.Select((a, i) => Expression.Constant(a, this.query.Parameters[i].Type)).ToArray() ); root = this.FindProviderInExpression(replaced); } if (root != null) { ConstantExpression cex = root as ConstantExpression; if (cex == null) { cex = PartialEvaluator.Eval(root) as ConstantExpression; } if (cex != null) { IQueryProvider provider = cex.Value as IQueryProvider; if (provider == null) { IQueryable query = cex.Value as IQueryable; if (query != null) { provider = query.Provider; } } return(provider); } } return(null); }