str.h

#ifndef STR_H_H
#define STR_H_H
#define MAX_NUM 20
#define MAX_REL_NAME 20
#define MAX_ATTR_NAME 20
#define MAX_ERROR_MESSAGE 20
#define MAX_DATA 50

/*
文件: str.h
内容: the definition of sqls' structs
*/
#include<stdlib.h>
#include<string.h>
#include "RC.h"

//属性结构体
typedef struct {
	char* relName;     // relation name (may be NULL) 表名
	char* attrName;    // attribute name              属性名
}RelAttr;

typedef enum {
	EQual,			//"="			0
	LEqual,			//"<="          1         
	NEqual,			//"<>"			2       
	LessT,			//"<"			3            
	GEqual,			//">="			4         
	GreatT,			//">"           5    
	NO_OP
}CompOp;

//属性值类型
typedef enum {
	chars,
	ints,
	floats
}AttrType;
//属性值
typedef struct _Value Value;
struct _Value {
	AttrType type;     // type of value               
	void* data;    // value    
};

typedef struct  _Condition Condition;
struct  _Condition {
	int     bLhsIsAttr;   // TRUE if left-hand side is an attribute
	Value   lhsValue;		// left-hand side value if bLhsIsAttr = FALSE 
	RelAttr lhsAttr;      // left-hand side attribute                     
	CompOp  op;           // comparison operator                          
	int     bRhsIsAttr;   // TRUE if right-hand side is an attribute
						  //   and not a value
	RelAttr rhsAttr;      // right-hand side attribute if bRhsIsAttr = TRUE
	Value   rhsValue;     // right-hand side value if bRhsIsAttr = FALSE 

};

//struct of select
typedef struct {
	int nSelAttrs;              	//Length of attrs in Select clause
	RelAttr* selAttrs[MAX_NUM];			//attrs in Select clause
	int nRelations;								//Length of relations in Fro clause
	char* relations[MAX_NUM];			//relations in From clause
	int nConditions;							//Length of conditions in Where clause 
	Condition conditions[MAX_NUM];//conditions in Where clause
}selects;

//struct of insert 
typedef struct {
	char* relName;				//Relation to insert into 
	int nValues;					//Length of values
	Value values[MAX_NUM];//values to insert
}inserts;

//struct of delete 
typedef struct {
	char* relName;										//Relation to delete from
	int nConditions;									//Length of conditions in Where clause 
	Condition conditions[MAX_NUM];	//conditions in Where clause
}deletes;

//struct of update 
typedef struct {
	char* relName;					//Relation to update
	char* attrName;					//Attribute to update
	Value value;						//update value
	int nConditions;				//Length of conditions in Where clause 
	Condition conditions[MAX_NUM];	// conditions in Where clause
}updates;

//struct of AttrInfo  
typedef struct _AttrInfo AttrInfo;
struct _AttrInfo {
	char* attrName;		//Attribute name
	AttrType attrType;		//Type of attribute
	int attrLength;		//Length of attribute
};
//struct of craete_table
typedef struct {
	char* relName;		//Relation name
	int attrCount;		//Length of attribute 
	AttrInfo attributes[MAX_NUM];	//attributes 
}createTable;

//struct of drop_table  
typedef struct {
	char* relName;		//Relation name
}dropTable;

//struct of create_index  
typedef struct {
	char* indexName;	// Index name
	char* relName;		// Relation name
	char* attrName;		// Attribute name
}createIndex;

//struct of  drop_index  
typedef struct {
	char* indexName;		// Index name

}dropIndex;

//union of sql_structs
union sqls {
	selects sel;
	inserts ins;
	deletes del;
	updates upd;
	createTable cret;
	dropTable drt;
	createIndex crei;
	dropIndex dri;
	char* errors;
};


// struct of flag and sql_struct
typedef struct {
	int flag;	/*match to the sqls 0--error;1--select;2--insert;3--update;4--delete;5--create table;6--drop table;7--create index;8--drop index;9--help;10--exit;*/
	union sqls sstr;
}sqlstr;

#ifdef __cplusplus
extern "C" {
	sqlstr* get_sqlstr();
	RC parse(char* st, sqlstr* sqln);
};
#endif
#endif