108 lines
4 KiB
C
108 lines
4 KiB
C
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#ifndef __STRING_TABLE_H
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#define __STRING_TABLE_H
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///////////////////////////////////////////////////////////////////////////////
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// Class: StringTable
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//
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// This class implements a simple hash table for storing text strings.
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// The purpose of the table is to store strings and then verify later
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// if the table contains a given string. Since there is no data associated
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// with the string, the stored strings act as both key and data. Therefore,
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// there is no requirement for string retrieval. Only existence checks
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// are required.
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// The structure maintains a fixed-length array of pointers, each pointing
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// to a linked list structure (List). These lists are used to handle the
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// problem of hash collisions (sometimes known as "separate chaining").
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//
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// Note that these classes do not contain all the stuff that is usually
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// considered necessary in C++ classes. Things like copy constructors,
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// assignment operator, type conversion etc are excluded. The classes
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// are very specialized for the Font Folder application and these things
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// would be considered "fat". Should this hash table class be later used
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// in a situation where these things are needed, they can be added then.
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//
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// The public interfaces to the table are:
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//
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// Initialize - Initialize a new string table.
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// Add - Add a new string to a table.
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// Exists - Determine if a string exists in a table.
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// Count - Return the number of strings in a table.
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//
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// Destruction of the object automatically releases all memory associated
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// with the table.
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//
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// BrianAu - 4/11/96
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///////////////////////////////////////////////////////////////////////////////
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#include <windows.h>
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#include <tchar.h>
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//
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// Hash table containing text strings.
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//
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class StringTable {
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private:
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//
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// Linked list for hash collisions.
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//
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class List {
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private:
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//
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// Element in hash collision list.
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//
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class Element {
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public:
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LPTSTR m_pszText; // Pointer to string text.
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Element *m_pNext; // Pointer to next in list.
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Element(void);
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~Element(void);
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BOOL Initialize(LPCTSTR pszItem);
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BOOL operator == (const Element& ele) const;
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BOOL operator != (const Element& ele) const;
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#ifdef DEBUG
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void DebugOut(void) const;
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#endif
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};
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Element *m_pHead; // Ptr to head of list;
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DWORD m_dwCount; // Count of elements in list.
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public:
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List(void);
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~List(void);
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BOOL Add(LPCTSTR pszText, BOOL bAllowDuplicates = TRUE);
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BOOL Exists(LPCTSTR pszText) const;
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DWORD Count(void) const { return m_dwCount; }
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#ifdef DEBUG
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void DebugOut(void) const;
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#endif
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};
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CRITICAL_SECTION m_cs; // Protect from concurrent access.
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List **m_apLists; // Array of ptrs to collision lists.
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DWORD m_dwItemCount; // Number of items in table.
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DWORD m_dwHashBuckets; // Number of pointers in hash array.
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BOOL m_bCaseSensitive; // Key strings treated case-sensitive?
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BOOL m_bAllowDuplicates; // Allow duplicate strings?
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DWORD Hash(LPCTSTR pszText) const;
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LPTSTR StringTable::CreateUpperCaseString(LPCTSTR pszText) const;
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BOOL Exists(DWORD dwHashCode, LPCTSTR pszText);
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public:
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StringTable(void);
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~StringTable(void);
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BOOL Initialize(DWORD dwHashBuckets,
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BOOL bCaseSensitive = TRUE,
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BOOL bAllowDuplicates = FALSE);
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BOOL IsInitialized(void);
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void Destroy(void);
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BOOL Add(LPCTSTR pszText);
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BOOL Exists(LPCTSTR pszText);
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DWORD Count(void) const { return m_dwItemCount; }
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#ifdef DEBUG
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void DebugOut(void) const;
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#endif
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};
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#endif
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