Query.cpp
资源名称:CppPrimer.rar [点击查看]
上传用户:qdkongtiao
上传日期:2022-06-29
资源大小:356k
文件大小:3k
源码类别:
书籍源码
开发平台:
Visual C++
- /*
- * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
- * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
- * copyright and warranty notices given in that book:
- *
- * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
- *
- *
- * "The authors and publisher have taken care in the preparation of this book,
- * but make no expressed or implied warranty of any kind and assume no
- * responsibility for errors or omissions. No liability is assumed for
- * incidental or consequential damages in connection with or arising out of the
- * use of the information or programs contained herein."
- *
- * Permission is granted for this code to be used for educational purposes in
- * association with the book, given proper citation if and when posted or
- * reproduced.Any commercial use of this code requires the explicit written
- * permission of the publisher, Addison-Wesley Professional, a division of
- * Pearson Education, Inc. Send your request for permission, stating clearly
- * what code you would like to use, and in what specific way, to the following
- * address:
- *
- * Pearson Education, Inc.
- * Rights and Contracts Department
- * 75 Arlington Street, Suite 300
- * Boston, MA 02216
- * Fax: (617) 848-7047
- */
- #include "Query.h"
- #include "TextQuery.h"
- #include <set>
- #include <algorithm>
- #include <iostream>
- using std::set;
- using std::ostream;
- using std::inserter;
- using std::set_difference;
- using std::set_union;
- using std::set_intersection;
- // returns lines not in its operand's result set
- set<TextQuery::line_no>
- NotQuery::eval(const TextQuery& file) const
- {
- // virtual call through the Query handle to eval
- set<TextQuery::line_no> has_val = query.eval(file);
- set<line_no> ret_lines;
- // for each line in the input file, check whether that line is in has_val
- // if not, add that line number to ret_lines
- for (TextQuery::line_no n = 0; n != file.size(); ++n)
- if (has_val.find(n) == has_val.end())
- ret_lines.insert(n);
- return ret_lines;
- }
- // returns intersection of its operands' result sets
- set<TextQuery::line_no>
- AndQuery::eval(const TextQuery& file) const
- {
- // virtual calls through the Query handle to get result sets for the operands
- set<line_no> left = lhs.eval(file),
- right = rhs.eval(file);
- set<line_no> ret_lines; // destination to hold results
- // writes intersection of two ranges to a destination iterator
- // destination iterator in this call adds elements to ret
- set_intersection(left.begin(), left.end(),
- right.begin(), right.end(),
- inserter(ret_lines, ret_lines.begin()));
- return ret_lines;
- }
- // returns union of its operands' result sets
- set<TextQuery::line_no>
- OrQuery::eval(const TextQuery& file) const
- {
- // virtual calls through the Query handle to get result sets for the operands
- set<line_no> right = rhs.eval(file),
- ret_lines = lhs.eval(file); // destination to hold results
- // inserts the lines from right that aren't already in ret_lines
- ret_lines.insert(right.begin(), right.end());
- return ret_lines;
- }