最近在看C++ Primer复习C++的语法，看到书中15.9章中的文本查询示例时，觉得设计得非常不错，于是便动手照着实现了一个，修改了很久终于运行成功了，从中也学习到了很多的语法。下面把实现与总结分享给大家：
首先是在10.6.2节中实现的TextQuery类：
TextQuery.h
#ifndef __TestC____TextQuery__
#define __TestC____TextQuery__
#include
#include
#include
#include
TextQuery.cpp
#include "TextQuery.h"
TextQuery::TextQuery(string strArray[], vector
::size_type count) {
lines_of_text.assign(strArray, strArray+count);
}
set
TextQuery::run_query(const string&word) const { set
ret_lines; for (int i=0;i
接下来是查询类的句柄类Query：
Query.h
#ifndef __TestC____Query__
#define __TestC____Query__
#include
#include "TextQuery.h"
class Query_base;
class Query {
friend Query operator~(const Query &);
friend Query operator|(const Query &, const Query &);
friend Query operator&(const Query &, const Query &);
public:
Query(const string &);
Query(const Query &);
virtual ~Query();
Query& operator=(const Query&);
set
eva l(const TextQuery&) const; ostream & display(ostream &) const; private: Query(Query_base *); Query_base *q; size_t *use; void decr_use(); }; inline ostream & operator<<(ostream &os, const Query &q) { return q.display(os); } #endif /* defined(__TestC____Query__) */
Query.cpp
#include "Query.h"
#include "Query_base.h"
Query::Query(const Query &c) : q(c.q), use(c.use) {
++*use;
}
Query::Query(const string &s) : q(new WordQuery(s)), use(new size_t(1)) {
}
Query::Query(Query_base *query) : q(query), use(new size_t(1)) {
}
Query::~Query() {
decr_use();
}
void Query::decr_use() {
if (--*use == 0) {
delete q;
delete use;
}
}
set
Query::eva l(const TextQuery &t) const{
return q->eva l(t);
}
ostream& Query::display(ostream &os) const {
return q->display(os);
}
接下来是最核心的各个查询类Query_base、WordQuery、NotQuery、AndQuery、OrQuery：
Query_base.h
#ifndef __TestC____Query_base__
#define __TestC____Query_base__
#include
#include "TextQuery.h"
#include "Query.h"
class Query_base {
friend class Query;
protected:
typedef TextQuery::line_no line_no;
virtual ~Query_base() {}
private:
virtual set
eva l(const TextQuery&) const = 0; virtual ostream & display(ostream & = cout) const = 0; }; class WordQuery : Query_base { friend class Query; WordQuery(const string &); set
eva l(const TextQuery&) const; ostream & display(ostream & = cout) const; string query_word; }; class NotQuery : public Query_base { friend Query operator~(const Query &); NotQuery(Query); set
eva l(const TextQuery&) const; ostream & display(ostream & = cout) const; const Query query; }; class BinaryQuery : public Query_base { protected: BinaryQuery(Query left, Query right, string op); ostream & display(ostream & = cout) const; const Query lhs, rhs; const string oper; }; class AndQuery : BinaryQuery { friend Query operator&(const Query&, const Query&); AndQuery(Query left, Query right); set
eva l(const TextQuery&) const; }; class OrQuery : BinaryQuery { friend Query operator|(const Query&, const Query&); OrQuery(Query left, Query right); set
eva l(const TextQuery&) const; }; #endif /* defined(__TestC____Query_base__) */
Query_base.cpp
#include "Query_base.h"
/**
* WordQuery
*/
WordQuery::WordQuery(con