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1 using System;
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2 using System.Collections.Generic;
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3 using System.Linq;
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4 using System.Text;
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5
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6 namespace BLToolkit.Data.Sql
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7 {
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8 public class SqlExpression : ISqlExpression
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9 {
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10 public SqlExpression(Type systemType, string expr, int precedence, params ISqlExpression[] parameters)
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11 {
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12 if (parameters == null) throw new ArgumentNullException("parameters");
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13
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14 foreach (var value in parameters)
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15 if (value == null) throw new ArgumentNullException("parameters");
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16
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17 SystemType = systemType;
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18 Expr = expr;
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19 Precedence = precedence;
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20 Parameters = parameters;
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21 }
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22
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23 public SqlExpression(string expr, int precedence, params ISqlExpression[] parameters)
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24 : this(null, expr, precedence, parameters)
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25 {
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26 }
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27
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28 public SqlExpression(Type systemType, string expr, params ISqlExpression[] parameters)
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29 : this(systemType, expr, Sql.Precedence.Unknown, parameters)
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30 {
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31 }
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32
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33 public SqlExpression(string expr, params ISqlExpression[] parameters)
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34 : this(null, expr, Sql.Precedence.Unknown, parameters)
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35 {
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36 }
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37
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38 public Type SystemType { get; private set; }
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39 public string Expr { get; private set; }
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40
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41 public int Precedence { get; private set; }
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42 public ISqlExpression[] Parameters { get; private set; }
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43
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44 #region Overrides
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45
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46 #if OVERRIDETOSTRING
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47
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48 public override string ToString()
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49 {
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50 return ((IQueryElement)this).ToString(new StringBuilder(), new Dictionary<IQueryElement,IQueryElement>()).ToString();
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51 }
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52
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53 #endif
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54
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55 #endregion
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56
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57 #region ISqlExpressionWalkable Members
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58
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59 [Obsolete]
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60 ISqlExpression ISqlExpressionWalkable.Walk(bool skipColumns, Func<ISqlExpression,ISqlExpression> func)
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61 {
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62 for (var i = 0; i < Parameters.Length; i++)
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63 Parameters[i] = Parameters[i].Walk(skipColumns, func);
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64
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65 return func(this);
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66 }
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67
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68 #endregion
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69
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70 #region IEquatable<ISqlExpression> Members
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71
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72 bool IEquatable<ISqlExpression>.Equals(ISqlExpression other)
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73 {
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74 return Equals(other, DefaultComparer);
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75 }
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76
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77 #endregion
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78
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79 #region ISqlExpression Members
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80
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81 public bool CanBeNull()
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82 {
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83 foreach (var value in Parameters)
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84 if (value.CanBeNull())
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85 return true;
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86
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87 return false;
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88 }
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89
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90 public static Func<ISqlExpression,ISqlExpression,bool> DefaultComparer = (x, y) => true;
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91
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92 public bool Equals(ISqlExpression other, Func<ISqlExpression,ISqlExpression,bool> comparer)
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93 {
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94 if (this == other)
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95 return true;
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96
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97 var expr = other as SqlExpression;
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98
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99 if (expr == null || SystemType != expr.SystemType || Expr != expr.Expr || Parameters.Length != expr.Parameters.Length)
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100 return false;
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101
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102 for (var i = 0; i < Parameters.Length; i++)
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103 if (!Parameters[i].Equals(expr.Parameters[i], comparer))
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104 return false;
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105
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106 return comparer(this, other);
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107 }
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108
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109 #endregion
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110
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111 #region ICloneableElement Members
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112
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113 public ICloneableElement Clone(Dictionary<ICloneableElement, ICloneableElement> objectTree, Predicate<ICloneableElement> doClone)
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114 {
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115 if (!doClone(this))
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116 return this;
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117
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118 ICloneableElement clone;
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119
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120 if (!objectTree.TryGetValue(this, out clone))
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121 {
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122 objectTree.Add(this, clone = new SqlExpression(
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123 SystemType,
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124 Expr,
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125 Precedence,
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126 Parameters.Select(e => (ISqlExpression)e.Clone(objectTree, doClone)).ToArray()));
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127 }
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128
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129 return clone;
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130 }
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131
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132 #endregion
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133
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134 #region IQueryElement Members
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135
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136 public QueryElementType ElementType { get { return QueryElementType.SqlExpression; } }
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137
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138 StringBuilder IQueryElement.ToString(StringBuilder sb, Dictionary<IQueryElement,IQueryElement> dic)
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139 {
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140 var len = sb.Length;
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141 var ss = Parameters.Select(p =>
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142 {
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143 p.ToString(sb, dic);
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144 var s = sb.ToString(len, sb.Length - len);
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145 sb.Length = len;
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146 return (object)s;
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147 });
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148
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149 return sb.AppendFormat(Expr, ss.ToArray());
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150 }
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151
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152 #endregion
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153
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154 #region Public Static Members
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155
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156 public static bool NeedsEqual(IQueryElement ex)
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157 {
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158 switch (ex.ElementType)
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159 {
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160 case QueryElementType.SqlParameter:
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161 case QueryElementType.SqlField :
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162 case QueryElementType.Column : return true;
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163 case QueryElementType.SqlFunction :
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164
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165 var f = (SqlFunction)ex;
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166
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167 switch (f.Name)
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168 {
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169 case "EXISTS" : return false;
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170 }
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171
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172 return true;
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173 }
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174
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175 return false;
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176 }
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177
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178 #endregion
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179 }
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180 }
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