Upload note code of chapter 5 associated container

Author: SilverMaple

5_STL_associated_container/5_7_2_stl_hashtable.h

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+/*
+ * Copyright (c) 1996-1998
+ * Silicon Graphics Computer Systems, Inc.
+ *
+ * Permission to use, copy, modify, distribute and sell this software
+ * and its documentation for any purpose is hereby granted without fee,
+ * provided that the above copyright notice appear in all copies and
+ * that both that copyright notice and this permission notice appear
+ * in supporting documentation.  Silicon Graphics makes no
+ * representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ *
+ * Copyright (c) 1994
+ * Hewlett-Packard Company
+ *
+ * Permission to use, copy, modify, distribute and sell this software
+ * and its documentation for any purpose is hereby granted without fee,
+ * provided that the above copyright notice appear in all copies and
+ * that both that copyright notice and this permission notice appear
+ * in supporting documentation.  Hewlett-Packard Company makes no
+ * representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ */
+
+/* NOTE: This is an internal header file, included by other STL headers.
+ *   You should not attempt to use it directly.
+ */
+
+#ifndef __SGI_STL_HASH_FUN_H
+#define __SGI_STL_HASH_FUN_H
+
+#include <stddef.h>
+
+__STL_BEGIN_NAMESPACE
+
+// 以下都是用仿函数实现hash function，重载不同数据类型
+
+template <class _Key> struct hash { };
+
+// 为字符串进行散列
+inline size_t __stl_hash_string(const char* __s)
+{
+  unsigned long __h = 0; 
+  for ( ; *__s; ++__s)
+    __h = 5*__h + *__s; // 采用元素层次相加
+  
+  return size_t(__h);
+}
+
+__STL_TEMPLATE_NULL struct hash<char*>
+{
+  size_t operator()(const char* __s) const { return __stl_hash_string(__s); }
+};
+
+__STL_TEMPLATE_NULL struct hash<const char*>
+{
+  size_t operator()(const char* __s) const { return __stl_hash_string(__s); }
+};
+
+__STL_TEMPLATE_NULL struct hash<char> {
+  size_t operator()(char __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<unsigned char> {
+  size_t operator()(unsigned char __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<signed char> {
+  size_t operator()(unsigned char __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<short> {
+  size_t operator()(short __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<unsigned short> {
+  size_t operator()(unsigned short __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<int> {
+  size_t operator()(int __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<unsigned int> {
+  size_t operator()(unsigned int __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<long> {
+  size_t operator()(long __x) const { return __x; }
+};
+__STL_TEMPLATE_NULL struct hash<unsigned long> {
+  size_t operator()(unsigned long __x) const { return __x; }
+};
+
+__STL_END_NAMESPACE
+
+#endif /* __SGI_STL_HASH_FUN_H */
+
+// Local Variables:
+// mode:C++
+// End:

5_STL_associated_container/5_7_4_stl_hash_fun.h

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+// file: 5hashtable-test.cpp
+
+// #include <hash_set> // for hashtable
+#include <backward/hashtable.h> // for hashtable in mingw c++
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    // hash-table
+    // <value, key, hash-func, extract-key, equal-key, allocator>
+    // note: hash-table has no default ctor
+
+    __gnu_cxx::hashtable<int,
+                         int,
+                         hash<int>,
+                         _Identity<int>,
+                         equal_to<int>,
+                         allocator<int>>
+        iht(50, hash<int>(), equal_to<int>()); // 指定50个buckets与函数对象
+
+    cout << iht.size() << endl; 
+    cout << iht.bucket_count() << endl;      // 第一个质数
+    cout << iht.max_bucket_count() << endl;  // 最后一个质数
+
+    iht.insert_unique(59);
+    iht.insert_unique(63);
+    iht.insert_unique(108);
+    iht.insert_unique(2);
+    iht.insert_unique(53);
+    iht.insert_unique(55);
+    cout << iht.size() << endl;
+
+    // 声明hashtable迭代器
+    // __gnu_cxx::hashtable<int,
+    //                      int,
+    //                      hash<int>,
+    //                      _Identity<int>,
+    //                      equal_to<int>,
+    //                      allocator<int>>
+    //     ::iterator ite = iht.begin();
+    // 使用auto可以避免上述长串，注意auto做函数返回类型时不会是引用
+    auto ite = iht.begin();
+
+    // 使用迭代器遍历hashtable输出所有节点值
+    for (int i = 0; i < iht.size(); ++i, ++ite)
+        cout << *ite << ' ';
+    cout << endl;
+
+    // 遍历所有buckets，如果节点个数不为0则打印
+    for (int i = 0; i < iht.bucket_count(); ++i) {
+        int n = iht.elems_in_bucket(i);
+        if (n!=0)
+            cout << "bucket[" << i << "] has " << n << " elems." << endl;
+    }
+
+    // 验证bucket(list)的容量就是buckets vector的大小
+    for (int i = 0; i <= 47; ++i) {
+        iht.insert_equal(i);
+    }
+    cout << iht.size() << endl;
+    cout << iht.bucket_count() << endl;
+
+    // 遍历所有buckets，如果节点个数不为0则打印
+    for (int i = 0; i < iht.bucket_count(); ++i) {
+        int n = iht.elems_in_bucket(i);
+        if (n!=0)
+            cout << "bucket[" << i << "] has " << n << " elems." << endl;
+    }
+
+    // 使用迭代器遍历hashtable输出所有节点值
+    ite = iht.begin();
+    for (int i = 0; i < iht.size(); ++i, ++ite)
+        cout << *ite << ' ';
+    cout << endl;
+
+    cout << *(iht.find(2)) << endl;
+    cout << iht.count(2) << endl;
+
+    // template argument deduction/substitution failed
+    // iht.insert_unique(string("jjhou")); 
+}

5_STL_associated_container/5_7_6_hashtable-test.cpp

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+// file: 5hashset-test.cpp
+
+#include <iostream>
+#include <hash_set>
+#include <cstring>
+
+using namespace std;
+
+// 仿函数
+struct eqstr {
+    bool operator() (const char* s1, const char* s2) const {
+        return strcmp(s1, s2) == 0;
+    }
+};
+
+void lookup(const __gnu_cxx::hash_set<const char*, hash<const char*>, eqstr>& Set, 
+            const char* word) {
+    __gnu_cxx::hash_set<const char *, hash<const char *>, eqstr>::const_iterator it = Set.find(word);
+    cout << " " << word << ": " << (it != Set.end() ? "present" : "not present") << endl;
+}
+
+int main() {
+    __gnu_cxx::hash_set<const char *, hash<const char *>, eqstr> Set;
+    Set.insert("kiwi");
+    Set.insert("plum");
+    Set.insert("apple");
+    Set.insert("mango");
+    Set.insert("apricot");
+    Set.insert("banana");
+
+    lookup(Set, "mango");
+    lookup(Set, "apple");
+    lookup(Set, "durian");
+
+    auto ite1 = Set.begin();
+    auto ite2 = Set.end();
+
+    for (; ite1 != ite2; ++ite1)
+        cout << *ite1 << ' ';
+    cout << endl;
+
+    __gnu_cxx::hash_set<int> iSet;
+    iSet.insert(59);
+    iSet.insert(63);
+    iSet.insert(108);
+    iSet.insert(2);
+    iSet.insert(53);
+    iSet.insert(55);
+
+    auto ite11 = iSet.begin();
+    auto ite22 = iSet.end();
+    // 为何已排序：
+    // 因为bucket为193（内置28个质数中大于100的最小质数）
+    // bucket足够多，造成排序假象
+    for (; ite11 != ite22; ++ite11)
+        cout << *ite11 << ' ';
+    cout << endl;
+
+    iSet.clear();
+    iSet.insert(3);
+    iSet.insert(196);
+    iSet.insert(1);
+    iSet.insert(389);
+    iSet.insert(194);
+    iSet.insert(387);
+    ite11 = iSet.begin();
+    for (; ite11 != ite22; ++ite11)
+        cout << *ite11 << ' ';
+    cout << endl;
+}