include/Predicate.h

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   2  *   Copyright (C) 2007 by www.databasecache.com                           *
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  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  14  *   GNU General Public License for more details.                          *
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  17 #ifndef PREDICATE_H
  18 #define PREDICATE_H
  19 #include<Expression.h>
  20 #include<DataType.h>
  21 class PredicateImpl;
  22 class Predicate;
  23 #ifndef AGGTYPE
  24 enum AggType
  25 {
  26     AGG_MIN = 1,
  27     AGG_MAX,
  28     AGG_SUM,
  29     AGG_AVG,
  30     AGG_COUNT,
  31     AGG_UNKNOWN
  32 };
  33 #define AGGTYPE
  34 #endif
  35
  36
  37 /**
  38 * @class Condition
  39 *
  40 * @brief Represents the condition part of SQL Query.
  41 * Used in SELECT, UPDATE and DELETE statement to retrieve only tuples which satisfy<br/>
  42 * the condition. This represents the root of the logical expression. This logical <br/>
  43 * expression may contain multiple terms(predicates).<br/>
  44 * For example to set this condition f1 == f2 && f1 == 100. <br/>
  45 *    Condition c1;<br/>
  46 *    int val1 = 100;<br/>
  47 *    c1.setTerm("f1", OpEquals, &val1);<br/>
  48 *    Predicate *p1 = c1.getPredicate();<br/>
  49 *    Condition c2;<br/>
  50 *    c2.setTerm("f1", opEquals, "f2");<br/>
  51 *    Predicate *p2 = c2.getPredicate();<br/>
  52 *    Condtion rootCondition;<br/>
  53 *    rootCondition.setTerm(p1, OpAnd, p2);<br/>
  54 *    table->setCondition(rootCondition);<br/>
  55 *
  56 */
  57 class DllExport Condition
  58 {
  59     Predicate *pred;
  60     public:
  61     Condition();
  62     ~Condition();
  63     void reset();
  64
  65     /** gets the current predicate. This is used to create logical expressions with terms or predicates.
  66     *   @return Predicate* predicate
  67     */
  68     Predicate* getPredicate() { return pred; }
  69
  70     /** sets the current predicate. This is set after creating the logical expression and used in the table interface for setting the condition.
  71     *   @param Predicate* predicate
  72     */
  73     void setPredicate(Predicate * predicate) {  pred = predicate; }
  74
  75
  76     /** sets the predicate term of form f1 = f2.
  77     *   @param fName1* field name
  78     *   @param op comparision operator
  79     *   @param fName2* field name
  80     */
  81     void setTerm(const char* fName1, ComparisionOp op, const char *fName2);
  82
  83     /** sets the predicate term of form f1 = 10
  84     *   @param fName1* field name
  85     *   @param op comparision operator(=,!=, >,<,>=,<=)
  86     *   @param opnd* pointer to the  value
  87     */
  88     void setTerm(const char* fName1, ComparisionOp op, void *opnd);
  89
  90     /** sets the predicate term of form f1 =10, using pointer semantics
  91     *   @param fName1* field name
  92     *   @param op comparision operator(=,!=, >,<,>=,<=)
  93     *   @param opnd** pointer to pointer to the  value
  94     */
  95     void setTerm(const char* fName1, ComparisionOp op, void **opnd );
  96     void setTerm(const char* fName1, ComparisionOp op, void **opnd, AggType aggType);
  97
  98
  99     /** sets the predicate term of form f1 = f2 && f1 = 100.
 100     *   @param p1* predicate
 101     *   @param op logical operator (&&, ||, !)
 102     *   @param p2* predicate
 103     */
 104     void setTerm(Predicate *p1, LogicalOp op, Predicate *p2 = NULL);
 105
 106 };
 107
 108 /**
 109 * @class Predicate
 110 *
 111 * @brief Represents a single term in the condition.
 112 * Condition is logical expression composed of terms and logical operators. This
 113 * represents the leaf of the logical expression tree. This is designed using composite
 114 * design pattern
 115 *
 116 *
 117 */
 118 class DllExport Predicate
 119 {
 120     public:
 121     virtual void setTerm(const char* fName1, ComparisionOp op, const char *fName2)=0;
 122
 123     //Operand should be of the same type of the field. This is must
 124     virtual void setTerm(const char* fName1, ComparisionOp op, void *opnd)=0;
 125
 126     //Operand should be of the same type of the field. This is must
 127     virtual void setTerm(const char* fName1, ComparisionOp op, void **opnd)=0;
 128
 129     virtual void setTerm(Predicate *p1, LogicalOp op, Predicate *p2 = NULL)=0;
 130     virtual void setTerm(const char* fName1, ComparisionOp op,bool nullFlag)=0;
 131     virtual void setTerm(Expression *exp, ComparisionOp op, void **opnd) = 0;
 132     virtual void setTerm(Expression *exp, ComparisionOp op, const char *fName2) = 0;
 133     virtual void setTerm(Expression *exp1, ComparisionOp op, Expression *exp2) = 0;
 134     virtual void print(int space)=0;
 135     virtual ~Predicate(){}
 136 };
 137
 138
 139 #endif