121 lines
3.6 KiB
C++
121 lines
3.6 KiB
C++
#ifndef __StringHeap_H
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#define __StringHeap_H
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/*
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* Copyright (c) 2002-2009 Stephen Williams (steve@icarus.com)
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*
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* This source code is free software; you can redistribute it
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* and/or modify it in source code form under the terms of the GNU
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* General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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# include <string>
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using namespace std;
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class perm_string {
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public:
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perm_string() : text_(0) { }
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perm_string(const perm_string&that) : text_(that.text_) { }
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~perm_string() { }
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perm_string& operator = (const perm_string&that)
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{ text_ = that.text_; return *this; }
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const char*str() const { return text_; }
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operator const char* () const { return str(); }
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// This is an escape for making perm_string objects out of
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// literals. For example, perm_string::literal("Label"); Please
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// do *not* cheat and pass arbitrary const char* items here.
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static perm_string literal(const char*t) { return perm_string(t); }
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private:
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friend class StringHeap;
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friend class StringHeapLex;
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perm_string(const char*t) : text_(t) { };
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private:
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const char*text_;
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};
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extern bool operator == (perm_string a, perm_string b);
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extern bool operator == (perm_string a, const char* b);
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extern bool operator != (perm_string a, perm_string b);
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extern bool operator != (perm_string a, const char* b);
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extern bool operator > (perm_string a, perm_string b);
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extern bool operator < (perm_string a, perm_string b);
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extern bool operator >= (perm_string a, perm_string b);
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extern bool operator <= (perm_string a, perm_string b);
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/*
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* The string heap is a way to permanently allocate strings
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* efficiently. They only take up the space of the string characters
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* and the terminating nul, there is no malloc overhead.
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*/
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class StringHeap {
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public:
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StringHeap();
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~StringHeap();
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const char*add(const char*);
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perm_string make(const char*);
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private:
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enum { HEAPCELL = 0x10000 };
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char*cell_base_;
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unsigned cell_ptr_;
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unsigned cell_count_;
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private: // not implemented
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StringHeap(const StringHeap&);
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StringHeap& operator= (const StringHeap&);
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};
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/*
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* A lexical string heap is a string heap that makes an effort to
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* return the same pointer for identical strings. This saves further
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* space by not allocating duplicate strings, so in a system with lots
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* of identifiers, this can theoretically save more space.
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*/
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class StringHeapLex : private StringHeap {
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public:
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StringHeapLex();
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~StringHeapLex();
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const char*add(const char*);
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perm_string make(const char*);
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perm_string make(const string&);
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unsigned add_count() const;
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unsigned add_hit_count() const;
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void cleanup();
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private:
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enum { HASH_SIZE = 4096 };
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const char*hash_table_[HASH_SIZE];
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unsigned add_count_;
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unsigned hit_count_;
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private: // not implemented
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StringHeapLex(const StringHeapLex&);
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StringHeapLex& operator= (const StringHeapLex&);
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};
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#endif
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