DataExpression.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / Filter / DataExpression.cs / 1 / DataExpression.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
// [....] 
//----------------------------------------------------------------------------- 

namespace System.Data { 
    using System;
    using System.Diagnostics;
    using System.Collections.Generic;
    using System.ComponentModel; 
    using System.Data.SqlTypes;
    using System.Data.Common; 
 
    internal sealed class DataExpression : IFilter {
        internal string originalExpression = null;  // original, unoptimized string 

        private bool parsed = false;
        private bool bound = false;
        private ExpressionNode expr = null; 
        private DataTable table = null;
        private readonly StorageType _storageType; 
        private readonly Type _dataType;  // This set if the expression is part of ExpressionCoulmn 
        private DataColumn[] dependency = DataTable.zeroColumns;
 
        internal DataExpression(DataTable table, string expression) : this(table, expression, null) {
        }

        internal DataExpression(DataTable table, string expression, Type type) { 
            ExpressionParser parser = new ExpressionParser(table);
            parser.LoadExpression(expression); 
 
            originalExpression = expression;
            expr = null; 

            if (expression != null) {
                _storageType = DataStorage.GetStorageType(type);
                _dataType = type; 
                expr = parser.Parse();
                parsed = true; 
                if (expr != null && table != null) { 
                    this.Bind(table);
                } 
                else {
                    bound = false;
                }
            } 
        }
 
        internal string Expression { 
            get {
                return (originalExpression != null ? originalExpression : ""); // 
            }
        }

        internal ExpressionNode ExpressionNode { 
            get {
                return expr; 
            } 
        }
 
        internal bool HasValue {
            get {
                return (null != expr);
            } 
        }
 
        internal void Bind(DataTable table) { 
            this.table = table;
 
            if (table == null)
                return;

            if (expr != null) { 
                Debug.Assert(parsed, "Invalid calling order: Bind() before Parse()");
                List list = new List(); 
                expr.Bind(table, list); 
                expr = expr.Optimize();
                this.table = table; 
                bound = true;
                dependency = list.ToArray();
            }
        } 

        internal bool DependsOn(DataColumn column) { 
            if (expr != null) { 
                return expr.DependsOn(column);
            } 
            else {
                return false;
            }
        } 

        internal object Evaluate() { 
            return Evaluate((DataRow)null, DataRowVersion.Default); 
        }
 
        internal object Evaluate(DataRow row, DataRowVersion version) {
            object result;

            if (!bound) { 
                this.Bind(this.table);
            } 
            if (expr != null) { 
                result = expr.Eval(row, version);
                // if the type is a SqlType (StorageType.Uri < _storageType), convert DBNull values. 
                if (result != DBNull.Value || StorageType.Uri < _storageType) {
                    // we need to convert the return value to the column.Type;
                    try {
                        if (StorageType.Object != _storageType) { 
                            result = SqlConvert.ChangeType2(result, _storageType, _dataType, table.FormatProvider);
                        } 
                    } 
                    catch (Exception e) {
                        // 
                        if (!ADP.IsCatchableExceptionType(e)) {
                            throw;
                        }
                        ExceptionBuilder.TraceExceptionForCapture(e); 

                        // 
 
                        throw ExprException.DatavalueConvertion(result, _dataType, e);
                    } 
                }
            }
            else {
                result = null; 
            }
            return result; 
        } 

        internal object Evaluate(DataRow[] rows) { 
            return Evaluate(rows, DataRowVersion.Default);
        }

 
        internal object Evaluate(DataRow[] rows, DataRowVersion version) {
            if (!bound) { 
                this.Bind(this.table); 
            }
            if (expr != null) { 
                List recordList = new List();
                foreach(DataRow row in rows) {
                    if (row.RowState == DataRowState.Deleted)
                        continue; 
                    if (version == DataRowVersion.Original && row.oldRecord == -1)
                        continue; 
                    recordList.Add(row.GetRecordFromVersion(version)); 
                }
                int[]  records = recordList.ToArray(); 
                return expr.Eval(records);
            }
            else {
                return DBNull.Value; 
            }
        } 
 
        public bool Invoke(DataRow row, DataRowVersion version) {
            if (expr == null) 
                return true;

            if (row == null) {
                throw ExprException.InvokeArgument(); 
            }
            object val = expr.Eval(row, version); 
            bool result; 
            try {
                result = ToBoolean(val); 
            }
            catch (EvaluateException) {
                throw ExprException.FilterConvertion(Expression);
            } 
            return result;
        } 
 
        internal DataColumn[] GetDependency() {
            Debug.Assert(dependency != null, "GetDependencies: null, we should have created an empty list"); 
            return dependency;
        }

        internal bool IsTableAggregate() { 
            if (expr != null)
                return expr.IsTableConstant(); 
            else 
                return false;
        } 

        internal static bool IsUnknown(object value) {
            return DataStorage.IsObjectNull(value);
        } 

        internal bool HasLocalAggregate() { 
            if (expr != null) 
                return expr.HasLocalAggregate();
            else 
                return false;
        }

        internal bool HasRemoteAggregate() { 
            if (expr != null)
                return expr.HasRemoteAggregate(); 
            else 
                return false;
        } 

        internal static bool ToBoolean(object value) {
            if (IsUnknown(value))
                return false; 
            if (value is bool)
                return(bool)value; 
            if (value is SqlBoolean){ 
                return (((SqlBoolean)value).IsTrue);
            } 
//check for SqlString is not added, value for true and false should be given with String, not with SqlString
            if (value is string) {
                try {
                    return Boolean.Parse((string)value); 
                }
                catch (Exception e) { 
                    // 
                    if (!ADP.IsCatchableExceptionType(e)) {
                        throw; 
                    }
                    ExceptionBuilder.TraceExceptionForCapture(e);
                    //
                    throw ExprException.DatavalueConvertion(value, typeof(bool), e); 
                }
            } 
 
            throw ExprException.DatavalueConvertion(value, typeof(bool), null);
        } 
    }


} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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DataExpression.cs source code in C# .NET

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