FromTableSubQuerySource.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;
using System.Linq;

using Deveel.Data.Sql.Expressions;

namespace Deveel.Data.Sql.Query {
    public class FromTableSubQuerySource : IFromTableSource {
        private ObjectName[] columnNames;

        internal FromTableSubQuerySource(bool caseInsensitive, string uniqueKey, SqlQueryExpression queryExpression,
            QueryExpressionFrom fromSet, ObjectName alias) {
            UniqueName = uniqueKey;
            QueryExpression = queryExpression;
            QueryFrom = fromSet;
            AliasName = alias;
            IgnoreCase = caseInsensitive;
        }

        public bool MatchesReference(string catalog, string schema, string table) {
            if (schema == null && table == null)
                return true;

            if (AliasName != null) {
                string ts = AliasName.Parent.Name;
                string tt = AliasName.Name;
                if (schema == null)
                    return StringCompare(tt, table);
                if (StringCompare(tt, table) && StringCompare(ts, schema))
                    return true;
            }

            // No way to determine if there is a match
            return false;
        }

        public SqlQueryExpression QueryExpression { get; private set; }

        public QueryExpressionFrom QueryFrom { get; private set; }

        public ObjectName AliasName { get; private set; }

        public bool IgnoreCase { get; private set; }

        public string UniqueName { get; private set; }

        public ObjectName[] ColumnNames {
            get {
                EnsureColumnNames();
                return columnNames;
            }
        }

        private void EnsureColumnNames() {
            if (columnNames == null) {
                columnNames = QueryFrom.GetResolvedColumns();

                // Are the variables aliased to a table name?
                if (AliasName != null) {
                    for (int i = 0; i < columnNames.Length; ++i) {
                        columnNames[i] = new ObjectName(AliasName, columnNames[i].Name);
                    }
                }
            }
        }

        private bool StringCompare(string str1, string str2) {
            var comparison = IgnoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal;
            return String.Equals(str1, str2, comparison);
        }

        private bool Matches(ObjectName name, string catalog, string schema, string table, string column) {
            var tableName = name.Parent;
            var schemaName = tableName == null ? null : tableName.Parent;
            var catalogName = schemaName == null ? null : schemaName.Parent;
            var columnName = name.Name;

            if (column == null)
                return true;
            if (!StringCompare(columnName, column))
                return false;

            if (table == null)
                return true;
            if (tableName == null)
                return false;

            string tname = tableName.Name;
            if (tname != null && !StringCompare(tname, table))
                return false;

            if (schema == null)
                return true;

            string sname = schemaName != null ? schemaName.Name : null;
            if (sname != null && !StringCompare(sname, schema))
                return false;

            string cname = catalogName != null ? catalogName.Name : null;
            if (cname != null && !StringCompare(cname, catalog))
                return false;

            return true;
        }

        public int ResolveColumnCount(string catalog, string schema, string table, string column) {
            EnsureColumnNames();

            if (String.IsNullOrEmpty(catalog) && 
                String.IsNullOrEmpty(schema) && 
                String.IsNullOrEmpty(table) && 
                String.IsNullOrEmpty(column))
                return columnNames.Length;

            return columnNames.Count(v => Matches(v, catalog, schema, table, column));

        }

        public ObjectName ResolveColumn(string catalog, string schema, string table, string column) {
            EnsureColumnNames();

            var result = columnNames.FirstOrDefault(v => Matches(v, catalog, schema, table, column));
            if (result == null)
                throw new InvalidOperationException("Couldn't resolve to a column.");

            return result;
        }
    }
}