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