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)); } }
private LambdaExpression Parameterize(Expression query, out object[] arguments) { IQueryProvider provider = this.FindProvider(query); if (provider == null) { throw new ArgumentException(Res.ArgumentQuery); } var ep = provider as IDbContext; // turn all relatively constant expression into actual constants Func <Expression, bool> fnCanBeEvaluated = e => ep != null?ExpressionHelper.CanBeEvaluatedLocally(e) : true; var body = PartialEvaluator.Eval(query, fnCanBeEvaluated); // convert all constants into parameters List <ParameterExpression> parameters; List <object> values; body = Parameterizer.Parameterize(body, out parameters, out values); // make sure the body will return a value typed as 'object'. if (body.Type != typeof(object)) { body = Expression.Convert(body, typeof(object)); } // make a lambda expression with these parameters arguments = values.ToArray(); if (arguments.Length < 5) { return(Expression.Lambda(body, parameters.ToArray())); } else { // too many parameters, use an object array instead. arguments = new object[] { arguments }; return(ExplicitToObjectArray.Rewrite(body, parameters)); } }
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"); } IEntityProvider ep = provider as IEntityProvider; Func <Expression, bool> fnCanBeEvaluated = (ep != null) ? new Func <Expression, bool>(ep.CanBeEvaluatedLocally) : null; List <ParameterExpression> parameters = new List <ParameterExpression>(); List <object> values = new List <object>(); Expression expression = PartialEvaluator.Eval(query, fnCanBeEvaluated, delegate(ConstantExpression c) { bool flag = c.Value is IQueryable; if (!((flag || (ep == null)) || ep.CanBeParameter(c))) { return(c); } ParameterExpression item = Expression.Parameter(c.Type, "p" + parameters.Count); parameters.Add(item); values.Add(c.Value); if (flag) { return(c); } return(item); }); if (expression.Type != typeof(object)) { expression = Expression.Convert(expression, typeof(object)); } arguments = values.ToArray(); if (arguments.Length < 5) { return(Expression.Lambda(expression, parameters.ToArray())); } arguments = new object[] { arguments }; return(ExplicitToObjectArray.Rewrite(expression, parameters)); }
internal static LambdaExpression Rewrite(Expression body, IList <ParameterExpression> parameters) { var visitor = new ExplicitToObjectArray(parameters); return(Expression.Lambda(visitor.Visit(body), visitor.array)); }