parse.c

#include "str.h"
#include "yacc_sql.tab.h"

selects * get_selects();
Condition * get_Condition();
RelAttr * get_RelAttr();
Value * get_Value();
union sqls * get_sqls();
sqlstr * get_sqlstr();
RC parse(char* st, sqlstr* sqln);


int i;
//allocate struct of condition
Condition *get_Condition() {
	Condition *condition;
	condition = (Condition *)malloc(sizeof(Condition));
	condition->lhsAttr = *get_RelAttr();
	condition->rhsAttr = *get_RelAttr();
	condition->lhsValue = *get_Value();
	condition->rhsValue = *get_Value();
	condition->bLhsIsAttr = -1;
	condition->bRhsIsAttr = -1;
	return condition;
}
//allocate struct of relattr
RelAttr *get_RelAttr() {
	RelAttr * relAttr;
	relAttr = (RelAttr*)malloc(sizeof(RelAttr));
	relAttr->relName = (char *)malloc(sizeof(char) * MAX_REL_NAME);
	memset(relAttr->relName, 0, sizeof(char)* MAX_REL_NAME);
	relAttr->attrName = (char *)malloc(sizeof(char) * MAX_ATTR_NAME);
	memset(relAttr->attrName, 0, sizeof(char)* MAX_ATTR_NAME);
	return relAttr;
}
//allocate struct of value,the default type is int
Value * get_Value() {
	Value * value = (Value *)malloc(sizeof(Value));
	value->data = (void *)malloc(sizeof(char)*MAX_DATA);
	memset(value->data, 0, sizeof(char) * MAX_DATA);
	value->type = ints;
	return value;
}
//allocate struct of select
selects *get_selects() {
	selects *se;
	se = (selects *)malloc(sizeof(selects));
	(se)->nSelAttrs = 0;
	for (i = 0; i < MAX_NUM; i++) {
		(se)->selAttrs[i] = get_RelAttr();
	}
	(se)->nRelations = 0;
	for (i = 0; i < MAX_NUM; i++) {
		(se)->relations[i] = (char*)malloc(sizeof(char));
		memset(se->relations[i], 0, sizeof(char));
	}
	(se)->nConditions = 0;
	for (i = 0; i < MAX_NUM; i++) {
		(se)->conditions[i] = *get_Condition();
	}
	return se;
}
//allocate union of sqls
union sqls *get_sqls() {
	union sqls *sql;
	sql = (union sqls *)malloc(sizeof(union sqls));
	(sql)->sel = *get_selects();
	(sql)->errors = (char *)malloc(sizeof(char)*MAX_ERROR_MESSAGE);
	memset(sql->errors, 0, sizeof(char) * MAX_ERROR_MESSAGE);
	return sql;
}
sqlstr *get_sqlstr() {
	sqlstr *sq;
	sq = (sqlstr *)malloc(sizeof(sqlstr));
	(sq)->flag = 0;
	(sq)->sstr = *get_sqls();
	return sq;
}

extern int hust_parse(sqlstr *sqls);
extern

RC parse(char* st, sqlstr* sqln) {

	yy_switch_to_buffer(yy_scan_string(st)); //sql语句进入缓存


	hust_parse(sqln);				//解析得到SQL语句，存在语句相应的结构体中 并返回
	/*判断flag的值，非零值返回CORRECT，为0时说明解析过程中出现语法错误，返回SQL_SYNTAX*/
	if (sqln->flag == 0)
		return SQL_SYNTAX;
	else
		return SUCCESS;

}