mozilla-history/js/js2/utilities.h

// -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
//
// The contents of this file are subject to the Netscape Public
// License Version 1.1 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of
// the License at http://www.mozilla.org/NPL/
//
// Software distributed under the License is distributed on an "AS
// IS" basis, WITHOUT WARRANTY OF ANY KIND, either express oqr
// implied. See the License for the specific language governing
// rights and limitations under the License.
//
// The Original Code is the JavaScript 2 Prototype.
//
// The Initial Developer of the Original Code is Netscape
// Communications Corporation.  Portions created by Netscape are
// Copyright (C) 1998 Netscape Communications Corporation. All
// Rights Reserved.

#ifndef utilities_h
#define utilities_h

#include "systemtypes.h"
#include <memory>
#include <new>
#include <string>
#include <iterator>
#include <algorithm>
#include <cstdio>
#include <cstdarg>

#ifndef _WIN32	// Microsoft Visual C++ 6.0 bug: standard identifiers should be in std namespace
 using std::size_t;
 using std::ptrdiff_t;
 using std::va_list;
 using std::strlen;
 using std::strcpy;
 using std::FILE;
 using std::getc;
 using std::fgets;
 using std::fputc;
 using std::fputs;
 using std::sprintf;
 using std::snprintf;
 using std::vsnprintf;
 using std::fprintf;
 #define STD std
 #define STATIC_CONST(type, expr) static const type expr
#else
 #define STD
 // Microsoft Visual C++ 6.0 bug: these identifiers should not begin with underscores
 #define snprintf _snprintf
 #define vsnprintf _vsnprintf
 // Microsoft Visual C++ 6.0 bug: constants not supported
 #define STATIC_CONST(type, expr) enum {expr}
#endif
using std::string;
using std::auto_ptr;

#ifdef __GNUC__ // why doesn't g++ support iterator?
namespace std {
	template<class Category, class T, class Distance = ptrdiff_t, class Pointer = T*, class Reference = T&>
	struct iterator {
		typedef T value_type;
		typedef Distance difference_type;
		typedef Pointer pointer;
		typedef Reference reference;
		typedef Category iterator_category;
	};
};
#endif


namespace JavaScript {


//
// Assertions
//

	#ifdef DEBUG
	 void Assert(const char *s, const char *file, int line);

	 #define ASSERT(_expr) ((_expr) ? (void)0 : JavaScript::Assert(#_expr, __FILE__, __LINE__))
	 #define NOT_REACHED(_reasonStr) JavaScript::Assert(_reasonStr, __FILE__, __LINE__)
	 #define DEBUG_ONLY(_stmt) _stmt
	#else
	 #define ASSERT(expr)
	 #define NOT_REACHED(reasonStr)
	 #define DEBUG_ONLY(_stmt)
	#endif


//
// Numerics
//

	template<class N> N min(N v1, N v2) {return v1 <= v2 ? v1 : v2;}
	template<class N> N max(N v1, N v2) {return v1 >= v2 ? v1 : v2;}


//
// Alignment
//

	template<typename T>
	struct AlignmentHelper {
		char ch;
		T t;
	};
	#define ALIGNMENT_OF(T) offsetof(JavaScript::AlignmentHelper<T>, t)


//
// Bit manipulation
//

	#define JS_BIT(n)       ((uint32)1 << (n))
	#define JS_BITMASK(n)   (JS_BIT(n) - 1)

	uint ceilingLog2(uint32 n);
	uint floorLog2(uint32 n);


//
// Unicode UTF-16 characters and strings
//

	// Special char16s
	namespace uni {
		const char16 null = '\0';
		const char16 cr = '\r';
		const char16 lf = '\n';
		const char16 space = ' ';
		const char16 ls = 0x2028;
		const char16 ps = 0x2029;
	}
	const uint16 firstFormatChar = 0x200C;	// Lowest Unicode Cf character
	
	inline char16 widen(char ch) {return static_cast<char16>(static_cast<uchar>(ch));}
	
	// Use char16Value to compare char16's for inequality because an implementation may have char16's
	// be either signed or unsigned.
	inline uint16 char16Value(char16 ch) {return static_cast<uint16>(ch);}

	// A string of UTF-16 characters.  Nulls are allowed just like any other character.
	// The string is not null-terminated.
	// Use wstring if char16 is wchar_t.  Otherwise use basic_string<uint16>.
	//
	// Eventually we'll want to use a custom class better suited for JavaScript that generates less
	// code bloat and separates the concepts of a fixed, read-only string from a mutable buffer that
	// is expanding.  For now, though, we use the standard basic_string.
	typedef std::basic_string<char16> String;


	typedef uint32 char16orEOF;		// A type that can hold any char16 plus one special value: ueof.
	const char16orEOF char16eof = static_cast<char16orEOF>(-1);

	// If c is a char16, return it; if c is char16eof, return the character \uFFFF.
	inline char16 char16orEOFToChar16(char16orEOF c) {return static_cast<char16>(c);}

#ifndef _WIN32
	// Return a String containing the characters of the null-terminated C string cstr
	// (without the trailing null).
	inline String widenCString(const char *cstr)
	{
		size_t len = strlen(cstr);
		const uchar *ucstr = reinterpret_cast<const uchar *>(cstr);
		return String(ucstr, ucstr+len);
	}


	// Widen and append length characters starting at chars to the end of str.
	inline void appendChars(String &str, const char *chars, size_t length)
	{
		const uchar *uchars = reinterpret_cast<const uchar *>(chars);
		str.append(uchars, uchars + length);
	}

	// Widen and append characters between begin and end to the end of str.
	inline void appendChars(String &str, const char *begin, const char *end)
	{
		ASSERT(begin <= end);
		str.append(reinterpret_cast<const uchar *>(begin), reinterpret_cast<const uchar *>(end));
	}

	// Widen and insert length characters starting at chars into the given position of str.
	inline void insertChars(String &str, String::size_type pos, const char *chars, size_t length)
	{
		ASSERT(pos <= str.size());
		const uchar *uchars = reinterpret_cast<const uchar *>(chars);
		str.insert(str.begin() + pos, uchars, uchars + length);
	}
#else // Microsoft VC6 bug: String constructor and append limited to char16 iterators
	String widenCString(const char *cstr);
	void appendChars(String &str, const char *chars, size_t length);
	inline void appendChars(String &str, const char *begin, const char *end)
	{
		ASSERT(begin <= end);
		appendChars(str, begin, static_cast<size_t>(end - begin));
	}
	void insertChars(String &str, String::size_type pos, const char *chars, size_t length);
#endif
	void insertChars(String &str, String::size_type pos, const char *cstr);


	String &operator+=(String &str, const char *cstr);
	String operator+(const String &str, const char *cstr);
	String operator+(const char *cstr, const String &str);
	inline String &operator+=(String &str, char c) {return str += widen(c);}
	inline void clear(String &s) {s.resize(0);}


	class CharInfo {
		uint32 info;					// Word from table a.

		// Unicode character attribute lookup tables
		static const uint8 x[];
		static const uint8 y[];
		static const uint32 a[];
	
	  public:
		// Enumerated Unicode general category types
		enum Type {
		    Unassigned            = 0,	// Cn
		    UppercaseLetter       = 1,	// Lu
		    LowercaseLetter       = 2,	// Ll
		    TitlecaseLetter       = 3,	// Lt
		    ModifierLetter        = 4,	// Lm
		    OtherLetter           = 5,	// Lo
		    NonSpacingMark        = 6,	// Mn
		    EnclosingMark         = 7,	// Me
		    CombiningSpacingMark  = 8,	// Mc
		    DecimalDigitNumber    = 9,	// Nd
		    LetterNumber          = 10,	// Nl
		    OtherNumber           = 11,	// No
		    SpaceSeparator        = 12,	// Zs
		    LineSeparator         = 13,	// Zl
		    ParagraphSeparator    = 14,	// Zp
		    Control               = 15,	// Cc
		    Format                = 16,	// Cf
		    PrivateUse            = 18,	// Co
		    Surrogate             = 19,	// Cs
		    DashPunctuation       = 20,	// Pd
		    StartPunctuation      = 21,	// Ps
		    EndPunctuation        = 22,	// Pe
		    ConnectorPunctuation  = 23,	// Pc
		    OtherPunctuation      = 24,	// Po
		    MathSymbol            = 25,	// Sm
		    CurrencySymbol        = 26,	// Sc
		    ModifierSymbol        = 27,	// Sk
		    OtherSymbol           = 28	// So
		};

		enum Group {
		    NonIdGroup,			// 0  May not be part of an identifier
		    FormatGroup,		// 1  Format control
		    IdGroup,			// 2  May start or continue a JS identifier (includes $ and _)
		    IdContinueGroup,	// 3  May continue a JS identifier  [(IdContinueGroup & -2) == IdGroup]
		    WhiteGroup,			// 4  White space character (but not line break)
		    LineBreakGroup		// 5  Line break character  [(LineBreakGroup & -2) == WhiteGroup]
		};

		CharInfo() {}
		CharInfo(char16 c): info(a[y[x[static_cast<uint16>(c)>>6]<<6 | c&0x3F]]) {}
		CharInfo(const CharInfo &ci): info(ci.info) {}

		friend Type cType(const CharInfo &ci) {return static_cast<Type>(ci.info & 0x1F);}
		friend Group cGroup(const CharInfo &ci) {return static_cast<Group>(ci.info >> 16 & 7);}

		friend bool isAlpha(const CharInfo &ci)
		{
			return ((1<<UppercaseLetter | 1<<LowercaseLetter | 1<<TitlecaseLetter | 1<<ModifierLetter | 1<<OtherLetter)
					 >> cType(ci) & 1) != 0;
		}

		friend bool isAlphanumeric(const CharInfo &ci)
		{
			return ((1<<UppercaseLetter | 1<<LowercaseLetter | 1<<TitlecaseLetter | 1<<ModifierLetter | 1<<OtherLetter |
					 1<<DecimalDigitNumber | 1<<LetterNumber)
					>> cType(ci) & 1) != 0;
		}

		// Return true if this character can start a JavaScript identifier
		friend bool isIdLeading(const CharInfo &ci) {return cGroup(ci) == IdGroup;}
		// Return true if this character can continue a JavaScript identifier
		friend bool isIdContinuing(const CharInfo &ci) {return (cGroup(ci) & -2) == IdGroup;}

		// Return true if this character is a Unicode decimal digit (Nd) character
		friend bool isDecimalDigit(const CharInfo &ci) {return cType(ci) == DecimalDigitNumber;}
		// Return true if this character is a Unicode white space or line break character
		friend bool isSpace(const CharInfo &ci) {return (cGroup(ci) & -2) == WhiteGroup;}
		// Return true if this character is a Unicode line break character (LF, CR, LS, or PS)
		friend bool isLineBreak(const CharInfo &ci) {return cGroup(ci) == LineBreakGroup;}
		// Return true if this character is a Unicode format control character (Cf)
		friend bool isFormat(const CharInfo &ci) {return cGroup(ci) == FormatGroup;}

		friend bool isUpper(const CharInfo &ci) {return cType(ci) == UppercaseLetter;}
		friend bool isLower(const CharInfo &ci) {return cType(ci) == LowercaseLetter;}

		friend char16 toUpper(char16 c);
		friend char16 toLower(char16 c);
	};
	
	inline bool isASCIIDecimalDigit(char16 c) {return c >= '0' && c <= '9';}
	bool isASCIIHexDigit(char16 c, uint &digit);

	const char16 *skipWhiteSpace(const char16 *str, const char16 *strEnd);


//
// Algorithms
//

	// Assign zero to every element between first inclusive and last exclusive.
	// This is equivalent ot fill(first, last, 0) but may be more efficient.
	template<class ForwardIterator>
	inline void zero(ForwardIterator first, ForwardIterator last)
	{
		while (first != last) {
			*first = 0;
			++first;
		}
	}


	// Assign zero to n elements starting at first.
	// This is equivalent ot fill_n(first, n, 0) but may be more efficient.
	template<class ForwardIterator, class Size>
	inline void zero_n(ForwardIterator first, Size n)
	{
		while (n) {
			*first = 0;
			++first;
			--n;
		}
	}

	// Same as find(first, last, value) but may be more efficient because it doesn't
	// use a reference for value.
	template<class InputIterator, class T>
	inline InputIterator findValue(InputIterator first, InputIterator last, T value)
	{
		while (first != last && !(*first == value))
			++first;
		return first;
	}


//
// Zones
//

	// A zone is a region of memory from which objects can be allocated individually.
	// The memory in a zone is deallocated when the zone is deallocated or its clear
	// method called.

	class Zone {
		union Header {
			Header *next;				// Next block header in linked list
			char padding[basicAlignment]; // Padding to ensure following block is fully aligned
		};								// Block data follows header
		
		Header *headers;				// Linked list of allocated blocks
		char *freeBegin;				// Pointer to free bytes left in current block
		char *freeEnd;					// Pointer to end of free bytes left in current block
		size_t blockSize;				// Size of individual arena blocks
		
	  public:
		explicit Zone(size_t blockSize = 1024);
	  private:
	    Zone(const Zone&);				// No copy constructor
	    void operator=(const Zone&);	// No assignment operator
	  public:
		void clear();
		~Zone() {clear();}
		
	  private:
		void *newBlock(size_t size);
	  public:
		void *allocate(size_t size);
		void *allocateUnaligned(size_t size);
	};


//
// Arenas
//

#ifndef _WIN32
	// Pretend that obj points to a value of class T and call obj's destructor.
	template<class T>
	void classDestructor(void *obj)
	{
		static_cast<T *>(obj)->~T();
	}
#else	// Microsoft Visual C++ 6.0 bug workaround
	template<class T>
	struct DestructorHolder {
		static void destroy(void *obj) {static_cast<T *>(obj)->~T();}
	};
#endif

	// An arena is a region of memory from which objects either derived from ArenaObject or allocated
	// using a ArenaAllocator can be allocated.  Deleting these objects individually runs the destructors,
	// if any, but does not deallocate the memory.  On the other hand, the entire arena can be deallocated
	// as a whole.
	//
	// One may also allocate other objects in an arena by using the Arena specialization of the global
	// operator new.  However, be careful not to delete any such objects explicitly!
	//
	// Destructors can be registered for objects (or parts of objects) allocated in the arena.  These
	// destructors are called, in reverse order of being registered, at the time the arena is deallocated
	// or cleared.  When registering destructors for an object O be careful not to delete O manually because that
	// would run its destructor twice.
	class Arena: public Zone {
		struct DestructorEntry;

		DestructorEntry *destructorEntries; // Linked list of destructor registrations, ordered from most to least recently registered
		
	  public:
		explicit Arena(size_t blockSize = 1024): Zone(blockSize), destructorEntries(0) {}
	  private:
		void runDestructors();
	  public:
		void clear() {runDestructors(); Zone::clear();}
		~Arena() {runDestructors();}
		
	  private:
		void newDestructorEntry(void (*destructor)(void *), void *object);
	  public:
		// Ensure that object's destructor is called at the time the arena is deallocated or cleared.
		// The destructors will be called in reverse order of being registered.
		// registerDestructor might itself runs out of memory, in which case it immediately
		// calls object's destructor before throwing bad_alloc.
#ifndef _WIN32
		template<class T> void registerDestructor(T *object) {newDestructorEntry(&classDestructor<T>, object);}
#else
		template<class T> void registerDestructor(T *object) {newDestructorEntry(&DestructorHolder<T>::destroy, object);}
#endif
	};

	
	// Objects derived from this class will be contained in the Arena passed to the new operator.
	struct ArenaObject {
		void *operator new(size_t size, Arena &arena) {return arena.allocate(size);}
		void *operator new[](size_t size, Arena &arena) {return arena.allocate(size);}
	  #ifndef __MWERKS__	// Metrowerks 5.3 bug: These aren't supported yet
		void operator delete(void *, Arena &) {}
		void operator delete[](void *, Arena &) {}
	  #endif
	  private:
		void operator delete(void *, size_t) {}
		void operator delete[](void *) {}
	};


	// Objects allocated by passing this class to standard containers will be contained in the Arena
	// passed to the ArenaAllocator's constructor.
	template<class T>
	class ArenaAllocator {
		Arena &arena;

	  public:
		typedef T value_type;
		typedef size_t size_type;
		typedef ptrdiff_t difference_type;
		typedef T *pointer;
		typedef const T *const_pointer;
		typedef T &reference;
		typedef const T &const_reference;
		
		static pointer address(reference r) {return &r;}
		static const_pointer address(const_reference r) {return &r;}
		
		ArenaAllocator(Arena &arena): arena(arena) {}
		template<class U> ArenaAllocator(const ArenaAllocator<U> &u): arena(u.arena) {}
		
		pointer allocate(size_type n, const void *hint = 0) {return static_cast<pointer>(arena.allocate(n*sizeof(T)));}
		static void deallocate(pointer, size_type) {}
		
		static void construct(pointer p, const T &val) {new(p) T(val);}
		static void destroy(pointer p) {p->~T();}
		
#ifdef __GNUC__ // why doesn't g++ support numeric_limits<T>?
        static size_type max_size() {return size_type(-1) / sizeof(T);}
#else
		static size_type max_size() {return std::numeric_limits<size_type>::max() / sizeof(T);}
#endif
		
		template<class U> struct rebind {typedef ArenaAllocator<U> other;};
	};


	String &newArenaString(Arena &arena);
	String &newArenaString(Arena &arena, const String &str);


//
// Pools
//

	// A Pool holds a collection of objects of the same type.  These objects can be
	// allocated and deallocated inexpensively.
	// To allocate a T, use new(pool) T(...), where pool has type Pool<T>.
	// To deallocate a T, use pool.destroy(t), where t has type T*.
	template <typename T>
	class Pool: public Zone {
		struct FreeList {
			FreeList *next;				// Next item in linked list of freed objects
		};
		STATIC_CONST(size_t, entrySize = sizeof(T) >= sizeof(FreeList *) ? sizeof(T) : sizeof(FreeList *));
		
		FreeList *freeList;				// Head of linked list of freed objects
		
	  public:
		// clumpSize is the number of T's that are allocated at a time.
		explicit Pool(size_t clumpSize): Zone(clumpSize * entrySize), freeList(0) {}

		// Allocate memory for a single T.  Use this with a placement new operator to create a new T.
		void *allocate() {if (freeList) {FreeList *p = freeList; freeList = p->next; return p;} return allocateUnaligned(entrySize);}
		void deallocate(void *t) {FreeList *p = static_cast<FreeList *>(t); p->next = freeList; freeList = p;}

		void destroy(T *t) {ASSERT(t); t->~T(); deallocate(t);}
	};


//
// Array auto_ptr's
//

	// An ArrayAutoPtr holds a pointer to an array initialized by new T[x].
	// A regular auto_ptr cannot be used here because it deletes its pointer using
	// delete rather than delete[].
	// An appropriate operator[] is also provided.
	template <typename T>
	class ArrayAutoPtr {
		T *ptr;
		
	  public:
		explicit ArrayAutoPtr(T *p = 0): ptr(p) {}
		ArrayAutoPtr(ArrayAutoPtr &a): ptr(a.ptr) {a.ptr = 0;}
		ArrayAutoPtr &operator=(ArrayAutoPtr &a) {reset(a.release());}
		~ArrayAutoPtr() {delete[] ptr;}
		
		T &operator*() const {return *ptr;}
		T &operator->() const {return *ptr;}
		template<class N> T &operator[](N i) const {return ptr[i];}
		T *get() const {return ptr;}
		T *release() {T *p = ptr; ptr = 0; return p;}
		void reset(T *p = 0) {delete[] ptr; ptr = p;}
	};
	
	typedef ArrayAutoPtr<char> CharAutoPtr;


//
// Growable Arrays
//

	// A Buffer initially points to inline storage of initialSize elements of type T.
	// The Buffer can be expanded via the expand method to increase its size by allocating
	// storage from the heap.
	template <typename T, size_t initialSize>
	class Buffer {
	  public:
		T *buffer;						// Pointer to the current buffer
		size_t size;					// Current size of the buffer
	  private:
		T initialBuffer[initialSize];	// Initial buffer
	  public:
	
		Buffer(): buffer(initialBuffer), size(initialSize) {}
		~Buffer() {if (buffer != initialBuffer) delete[] buffer;}
		
		void expand(size_t newSize);
	};

	// Expand the buffer to size newSize, which must be greater than the current size.
	// The buffer's contents are not preserved.
	template <typename T, size_t initialSize>
	inline void Buffer<T, initialSize>::expand(size_t newSize) {
		ASSERT(newSize > size);
		if (buffer != initialBuffer) {
			delete[] buffer;
			buffer = 0;	// For exception safety if the allocation below fails.
		}
		buffer = new T[newSize];
		size = newSize;
	}


	// See ArrayBuffer below.
	template <typename T>
	class RawArrayBuffer {
		T *const cache;					// Pointer to a fixed-size cache for holding the buffer if it's small enough
	  protected:
		T *buffer;						// Pointer to the current buffer
		size_t length;					// Logical size of the buffer
		size_t bufferSize;				// Physical size of the buffer
	  #ifdef DEBUG
		size_t maxReservedSize;			// Maximum size reserved so far
	  #endif

	  public:
		RawArrayBuffer(T *cache, size_t cacheSize): cache(cache), buffer(cache), length(0), bufferSize(cacheSize)
			{DEBUG_ONLY(maxReservedSize = 0);}
	  private:
	    RawArrayBuffer(const RawArrayBuffer&);	// No copy constructor
	    void operator=(const RawArrayBuffer&);	// No assignment operator
	  public:
	    ~RawArrayBuffer() {if (buffer != cache) delete[] buffer;}

	  private:
		void enlarge(size_t newLength);
	  public:

		// Methods that do not expand the buffer cannot throw exceptions.
	    size_t size() const {return length;}
		operator bool() const {return length != 0;}
		bool operator !() const {return length == 0;}

		T &front() {ASSERT(length); return *buffer;}
		const T &front() const {ASSERT(length); return *buffer;}
		T &back() {ASSERT(length); return buffer[length-1];}
		const T &back() const {ASSERT(length); return buffer[length-1];}
	    T *contents() const {return buffer;}

		void reserve(size_t nElts);
		T *reserve_back(size_t nElts = 1);
		T *advance_back(size_t nElts = 1);
		T *reserve_advance_back(size_t nElts = 1);

		void fast_push_back(const T &elt);
		void push_back(const T &elt);
	    void append(const T *elts, size_t nElts);
	    void append(const T *begin, const T *end) {ASSERT(end >= begin); append(begin, static_cast<size_t>(end - begin));}

		T &pop_back() {ASSERT(length); return buffer[--length];}
	};


	// Enlarge the buffer so that it can hold at least newLength elements.
	// May throw an exception, in which case the buffer is left unchanged.
	template <typename T>
	void RawArrayBuffer<T>::enlarge(size_t newLength) {
		size_t newBufferSize = bufferSize * 2;
		if (newBufferSize < newLength)
			newBufferSize = newLength;

        auto_ptr<T> newBuffer(new T[newBufferSize]);
        T *oldBuffer = buffer;
        std::copy(oldBuffer, oldBuffer + length, newBuffer.get());
        buffer = newBuffer.release();
        if (oldBuffer != cache)
            delete[] oldBuffer;
        bufferSize = newBufferSize;
	}

	// Ensure that there is room to hold nElts elements in the buffer, without expanding the
	// buffer's logical length.
	// May throw an exception, in which case the buffer is left unchanged.
	template <typename T>
	inline void RawArrayBuffer<T>::reserve(size_t nElts) {
		if (bufferSize < nElts)
			enlarge(nElts);
	  #ifdef DEBUG
		if (maxReservedSize < nElts)
			maxReservedSize = nElts;
	  #endif
	}

	// Ensure that there is room to hold nElts more elements in the buffer, without expanding the
	// buffer's logical length.  Return a pointer to the first element just past the logical length.
	// May throw an exception, in which case the buffer is left unchanged.
	template <typename T>
	inline T *RawArrayBuffer<T>::reserve_back(size_t nElts) {
		reserve(length + nElts);
		return buffer[length];
	}

	// Advance the logical length by nElts, assuming that the memory has previously been reserved.
	// Return a pointer to the first new element.
	template <typename T>
	inline T *RawArrayBuffer<T>::advance_back(size_t nElts) {
		ASSERT(length + nElts <= maxReservedSize);
		T *p = buffer + length;
		length += nElts;
		return p;
	}

	// Combine the effects of reserve_back and advance_back.
	template <typename T>
	inline T *RawArrayBuffer<T>::reserve_advance_back(size_t nElts) {
		reserve(length + nElts);
		T *p = buffer + length;
		length += nElts;
		return p;
	}

	// Same as push_back but assumes that the memory has previously been reserved.
	// May throw an exception if copying elt throws one, in which case the buffer is left unchanged.
	template <typename T>
	inline void RawArrayBuffer<T>::fast_push_back(const T &elt) {
		ASSERT(length < maxReservedSize);
		buffer[length] = elt;
		++length;
	}

	// Append elt to the back of the buffer.
	// May throw an exception, in which case the buffer is left unchanged.
	template <typename T>
	inline void RawArrayBuffer<T>::push_back(const T &elt) {
		*reserve_back() = elt;
		++length;
	}

	// Append nElts elements elts to the back of the array buffer.
	// May throw an exception, in which case the buffer is left unchanged.
	template <typename T>
	void RawArrayBuffer<T>::append(const T *elts, size_t nElts)
	{
	    size_t newLength = length + nElts;
	    if (newLength > bufferSize)
	    	enlarge(newLength);
	    std::copy(elts, elts + nElts, buffer + length);
	    length = newLength;
	}


	// An ArrayBuffer represents an array of elements of type T.  The ArrayBuffer contains
	// storage for a fixed size array of cacheSize elements; if this size is exceeded, the
	// ArrayBuffer allocates the array from the heap.  Elements can be appended to the back
	// of the array using append.  An ArrayBuffer can also act as a stack: elements can be
	// pushed and popped from the back.
	//
	// All ArrayBuffer operations are atomic with respect to exceptions -- either they
	// succeed or they do not affect the ArrayBuffer's existing elements and length.
	// If T has a constructor, it must have a constructor with no arguments; that constructor
	// is called at the time memory for the ArrayBuffer is allocated, just like when
	// allocating a regular C++ array.
	template <typename T, size_t cacheSize>
	class ArrayBuffer: public RawArrayBuffer<T> {
	    T cacheArray[cacheSize];
	  public:
	    ArrayBuffer(): RawArrayBuffer<T>(cacheArray, cacheSize) {}
	};


//
// Array Queues
//

	// See ArrayQueue below.
	template <typename T>
	class RawArrayQueue {
		T *const cache;					// Pointer to a fixed-size cache for holding the buffer if it's small enough
	  protected:
	    T *buffer;						// Pointer to the current buffer
	    T *bufferEnd;					// Pointer to the end of the buffer
	    T *f;							// Front end of the circular buffer, used for reading elements; buffer <= f < bufferEnd
	    T *b;							// Back end of the circular buffer, used for writing elements; buffer < b <= bufferEnd
	    size_t length;					// Number of elements used in the circular buffer
	    size_t bufferSize;				// Physical size of the buffer
	  #ifdef DEBUG
		size_t maxReservedSize;			// Maximum size reserved so far
	  #endif

	  public:
		RawArrayQueue(T *cache, size_t cacheSize):
			cache(cache), buffer(cache), bufferEnd(cache + cacheSize), f(cache), b(cache), length(0), bufferSize(cacheSize)
			{DEBUG_ONLY(maxReservedSize = 0);}
	  private:
	    RawArrayQueue(const RawArrayQueue&);	// No copy constructor
	    void operator=(const RawArrayQueue&);	// No assignment operator
	  public:
		~RawArrayQueue() {if (buffer != cache) delete[] buffer;}

	  private:
		void enlarge(size_t newLength);
	  public:

		// Methods that do not expand the buffer cannot throw exceptions.
		size_t size() const {return length;}
		operator bool() const {return length != 0;}
		bool operator !() const {return length == 0;}

		T &front() {ASSERT(length); return *f;}
		const T &front() const {ASSERT(length); return *f;}
		T &back() {ASSERT(length); return b[-1];}
		const T &back() const {ASSERT(length); return b[-1];}

		T &pop_front() {ASSERT(length); --length; T &elt = *f++; if (f == bufferEnd) f = buffer; return elt;}
		size_t pop_front(size_t nElts, T *&begin, T *&end);
		T &pop_back() {ASSERT(length); --length; T &elt = *--b; if (b == buffer) b = bufferEnd; return elt;}

		void reserve_back();
		void reserve_back(size_t nElts);
		T *advance_back();
		T *advance_back(size_t nElts, size_t &nEltsAdvanced);

		void fast_push_back(const T &elt);
		void push_back(const T &elt);

		// Same as append but assumes that memory has previously been reserved.
		// Does not throw exceptions.  T::operator= must not throw exceptions.
		template <class InputIter> void fast_append(InputIter begin, InputIter end) {
			size_t nElts = static_cast<size_t>(std::distance(begin, end));
			ASSERT(length + nElts <= maxReservedSize);
			while (nElts) {
				size_t nEltsAdvanced;
				T *dst = advance_back(nElts, nEltsAdvanced);
				nElts -= nEltsAdvanced;
				while (nEltsAdvanced--) {
					*dst = *begin; ++dst; ++begin;
				}
			}
		}

		// Append elements from begin to end to the back of the queue.  T::operator= must not throw exceptions.
		// reserve_back may throw an exception, in which case the queue is left unchanged.
		template <class InputIter> void append(InputIter begin, InputIter end) {
			size_t nElts = static_cast<size_t>(std::distance(begin, end));
			reserve_back(nElts);
			while (nElts) {
				size_t nEltsAdvanced;
				T *dst = advance_back(nElts, nEltsAdvanced);
				nElts -= nEltsAdvanced;
				while (nEltsAdvanced--) {
					*dst = *begin; ++dst; ++begin;
				}
			}
		}
	};

	// Pop between one and nElts elements from the front of the queue.  Set begin and end
	// to an array of the first n elements, where n is the return value.  The popped elements
	// may be accessed until the next non-const operation.
	// Does not throw exceptions.
	template <typename T>
	size_t RawArrayQueue<T>::pop_front(size_t nElts, T *&begin, T *&end) {
		ASSERT(nElts <= length);
		begin = f;
		size_t eltsToEnd = static_cast<size_t>(bufferEnd - f);
		if (nElts < eltsToEnd) {
			length -= nElts;
			f += nElts;
			end = f;
			return nElts;
		} else {
			length -= eltsToEnd;
			end = bufferEnd;
			f = buffer;
			return eltsToEnd;
		}
	}

	// Enlarge the buffer so that it can hold at least newLength elements.
	// May throw an exception, in which case the queue is left unchanged.
	template <typename T>
	void RawArrayQueue<T>::enlarge(size_t newLength) {
		size_t newBufferSize = bufferSize * 2;
		if (newBufferSize < newLength)
			newBufferSize = newLength;

        auto_ptr<T> newBuffer(new T[newBufferSize]);
        T *oldBuffer = buffer;
		size_t eltsToEnd = static_cast<size_t>(bufferEnd - f);
		if (eltsToEnd <= length)
	        std::copy(f, f + eltsToEnd, newBuffer.get());
		else {
	        std::copy(f, bufferEnd, newBuffer.get());
	        std::copy(oldBuffer, b, newBuffer.get() + eltsToEnd);
		}
        buffer = newBuffer.release();
        f = buffer;
        b = buffer + length;
        if (oldBuffer != cache)
            delete[] oldBuffer;
        bufferSize = newBufferSize;
	}

	// Ensure that there is room to hold one more element at the back of the queue, without expanding the
	// queue's logical length.
	// May throw an exception, in which case the queue is left unchanged.
	template <typename T>
	inline void RawArrayQueue<T>::reserve_back() {
		if (length == bufferSize)
			enlarge(length + 1);
	  #ifdef DEBUG
		if (maxReservedSize <= length)
			maxReservedSize = length + 1;
	  #endif
	}

	// Ensure that there is room to hold nElts more elements at the back of the queue, without expanding the
	// queue's logical length.
	// May throw an exception, in which case the queue is left unchanged.
	template <typename T>
	inline void RawArrayQueue<T>::reserve_back(size_t nElts) {
		nElts += length;
		if (bufferSize < nElts)
			enlarge(nElts);
	  #ifdef DEBUG
		if (maxReservedSize < nElts)
			maxReservedSize = nElts;
	  #endif
	}

	// Advance the back of the queue by one element, assuming that the memory has previously been reserved.
	// Return a pointer to that new element.
	// Does not throw exceptions.
	template <typename T>
	inline T *RawArrayQueue<T>::advance_back() {
		ASSERT(length < maxReservedSize);
	  	++length;
	  	if (b == bufferEnd)
	  		b = buffer;
	  	return b++;
	}

	// Advance the back of the queue by between one and nElts elements and return a pointer to them,
	// assuming that the memory has previously been reserved.
	// nEltsAdvanced gets the actual number of elements advanced.
	// Does not throw exceptions.
	template <typename T>
	T *RawArrayQueue<T>::advance_back(size_t nElts, size_t &nEltsAdvanced) {
		size_t newLength = length + nElts;
		ASSERT(newLength <= maxReservedSize);
		if (nElts) {
			T *b2 = b;
			if (b2 == bufferEnd)
				b2 = buffer;

			size_t room = static_cast<size_t>(bufferEnd - b2);
			if (nElts > room) {
				nElts = room;
				newLength = length + nElts;
			}
			length = newLength;
			nEltsAdvanced = nElts;
			b = b2 + nElts;
			return b2;
		} else {
			nEltsAdvanced = 0;
			return 0;
		}
	}

	// Same as push_back but assumes that the memory has previously been reserved.
	// May throw an exception if copying elt throws one, in which case the queue is left unchanged.
	template <typename T>
	inline void RawArrayQueue<T>::fast_push_back(const T &elt) {
		ASSERT(length < maxReservedSize);
		T *b2 = b;
	  	if (b2 == bufferEnd)
	  		b2 = buffer;
	  	*b2 = elt;
		b = b2 + 1;
		++length;
	}

	// Append elt to the back of the queue.
	// May throw an exception, in which case the queue is left unchanged.
	template <typename T>
	inline void RawArrayQueue<T>::push_back(const T &elt) {
		reserve_back();
		T *b2 = b == bufferEnd ? buffer : b;
		*b2 = elt;
		b = b2 + 1;
		++length;
	}


	// An ArrayQueue represents an array of elements of type T that can be written at its
	// back end and read at its front or back end.  In addition, arrays of multiple elements may be
	// written at the back end or read at the front end.  The ArrayQueue contains storage for a fixed size
	// array of cacheSize elements; if this size is exceeded, the ArrayQueue allocates the
	// array from the heap.
	template <typename T, size_t cacheSize>
	class ArrayQueue: public RawArrayQueue<T> {
	    T cacheArray[cacheSize];
	  public:
	    ArrayQueue(): RawArrayQueue<T>(cacheArray, cacheSize) {}
	};


//
// Linked Lists
//

	// In some cases it is desirable to manipulate ordinary C-style linked lists as though
	// they were STL-like sequences.  These classes define STL forward iterators that walk
	// through singly-linked lists of objects threaded through fields named 'next'.  The type
	// parameter E must be a class that has a member named 'next' whose type is E* or const E*.

	template <class E>
	class ListIterator: public std::iterator<std::forward_iterator_tag, E> {
		E *element;

	  public:
		ListIterator() {}
		explicit ListIterator(E *e): element(e) {}

		E &operator*() const {return *element;}
		E *operator->() const {return element;}
		ListIterator &operator++() {element = element->next; return *this;}
		ListIterator operator++(int) {ListIterator i(*this); element = element->next; return i;}
		friend bool operator==(const ListIterator &i, const ListIterator &j) {return i.element == j.element;}
		friend bool operator!=(const ListIterator &i, const ListIterator &j) {return i.element != j.element;}
	};

	
	template <class E>
  #ifndef _WIN32 // Microsoft VC6 bug: std::iterator should support five template arguments
	class ConstListIterator: public std::iterator<std::forward_iterator_tag, E, ptrdiff_t, const E*, const E&> {
  #else
	class ConstListIterator: public std::iterator<std::forward_iterator_tag, E, ptrdiff_t> {
  #endif
		const E *element;

	  public:
		ConstListIterator() {}
		ConstListIterator(const ListIterator<E> &i): element(&*i) {}
		explicit ConstListIterator(const E *e): element(e) {}

		const E &operator*() const {return *element;}
		const E *operator->() const {return element;}
		ConstListIterator &operator++() {element = element->next; return *this;}
		ConstListIterator operator++(int) {ConstListIterator i(*this); element = element->next; return i;}
		friend bool operator==(const ConstListIterator &i, const ConstListIterator &j) {return i.element == j.element;}
		friend bool operator!=(const ConstListIterator &i, const ConstListIterator &j) {return i.element != j.element;}
	};


//
// Doubly Linked Lists
//

	// A ListQueue provides insert and delete operations on a doubly-linked list of objects
	// threaded through fields named 'next' and 'prev'.  The type parameter E must be a class
	// derived from ListQueueEntry.
	// The ListQueue does not own its elements.  They must be deleted explicitly if needed.
	
	struct ListQueueEntry {
		ListQueueEntry *next;			// Next entry in linked list
		ListQueueEntry *prev;			// Previous entry in linked list
	
	  #ifdef DEBUG
		ListQueueEntry(): next(0), prev(0) {}
	  #endif
	};

	template <class E>
	struct ListQueue: private ListQueueEntry {
		ListQueue() {next = this; prev = this;}
	
		operator bool() const {return next != static_cast<const ListQueueEntry *>(this);}	// Return true if the ListQueue is nonempty
		bool operator !() const {return next == static_cast<const ListQueueEntry *>(this);}	// Return true if the ListQueue is empty

		E &front() const {ASSERT(operator bool()); return *static_cast<E *>(next);}
		E &back() const {ASSERT(operator bool()); return *static_cast<E *>(prev);}

		void push_front(E &elt) {ASSERT(!elt.next && !elt.prev); elt.next = next; elt.prev = this; next->prev = &elt; next = &elt;}
		void push_back(E &elt) {ASSERT(!elt.next && !elt.prev); elt.next = this; elt.prev = prev; prev->next = &elt; prev = &elt;}
		E &pop_front() {ASSERT(operator bool()); E *elt = static_cast<E *>(next); next = elt->next; next->prev = this;
						DEBUG_ONLY(elt->next = 0; elt->prev = 0;) return *elt;}
		E &pop_back() {ASSERT(operator bool()); E *elt = static_cast<E *>(prev); prev = elt->prev; prev->next = this;
					   DEBUG_ONLY(elt->next = 0; elt->prev = 0;) return *elt;}
	};


//
// Bit Sets
//

	template<size_t size>
	class BitSet {
		STATIC_CONST(size_t, nWords = (size+31)>>5);
		STATIC_CONST(uint32, lastWordMask = (2u<<((size-1)&31)) - 1);
		uint32 words[nWords];		// Bitmap of bits.  The first word contains bits 0(LSB)...31(MSB), the second contains bits 32...63, etc.

	  public:
		void clear() {zero(words, words+nWords);}
		BitSet() {clear();}
		// Construct a BitSet out of an array of alternating low (inclusive) and high (exclusive) ends of ranges of set bits.
		// The array is terminated by a 0,0 range.
		template<typename In> explicit BitSet(In a) {clear(); size_t low, high; while (low = *a++, (high = *a++) != 0) setRange(low, high);}
		
		bool operator[](size_t i) const {ASSERT(i < size); return static_cast<bool>(words[i>>5]>>(i&31) & 1);}
		bool none() const;
		bool operator==(const BitSet &s) const;
		bool operator!=(const BitSet &s) const;

		void set(size_t i) {ASSERT(i < size); words[i>>5] |= 1u<<(i&31);}
		void reset(size_t i) {ASSERT(i < size); words[i>>5] &= ~(1u<<(i&31));}
		void flip(size_t i) {ASSERT(i < size); words[i>>5] ^= 1u<<(i&31);}
		void setRange(size_t low, size_t high);
		void resetRange(size_t low, size_t high);
		void flipRange(size_t low, size_t high);
	};
	
	// Return true if all bits are clear.
	template<size_t size>
	inline bool BitSet<size>::none() const {
		if (nWords == 1)
			return !words[0];
		else {
			const uint32 *w = words;
			while (w != words + nWords)
				if (*w++)
					return false;
			return true;
		}
	}
	
	// Return true if the BitSets are equal.
	template<size_t size>
	inline bool BitSet<size>::operator==(const BitSet &s) const {
		if (nWords == 1)
			return words[0] == s.words[0];
		else
			return std::equal(words, s.words);
	}

	// Return true if the BitSets are not equal.
	template<size_t size>
	inline bool BitSet<size>::operator!=(const BitSet &s) const {
		return !operator==(s);
	}
	
	// Set all bits between low inclusive and high exclusive.
	template<size_t size>
	void BitSet<size>::setRange(size_t low, size_t high) {
		ASSERT(low <= high && high <= size);
		if (low != high)
			if (nWords == 1)
				words[0] |= (2u<<(high-1)) - (1u<<low);
			else {
				--high;
				uint32 *w = words + (low>>5);
				uint32 *wHigh = words + (high>>5);
				uint32 l = 1u << (low&31);
				uint32 h = 2u << (high&31);
				if (w == wHigh)
					*w |= h - l;
				else {
					*w++ |= -l;
					while (w != wHigh)
						*w++ = static_cast<uint32>(-1);
					*w |= h - 1;
				}
			}
	}

	// Clear all bits between low inclusive and high exclusive.
	template<size_t size>
	void BitSet<size>::resetRange(size_t low, size_t high) {
		ASSERT(low <= high && high <= size);
		if (low != high)
			if (nWords == 1)
				words[0] &= (1u<<low) - 1 - (2u<<(high-1));
			else {
				--high;
				uint32 *w = words + (low>>5);
				uint32 *wHigh = words + (high>>5);
				uint32 l = 1u << (low&31);
				uint32 h = 2u << (high&31);
				if (w == wHigh)
					*w &= l - 1 - h;
				else {
					*w++ &= l - 1;
					while (w != wHigh)
						*w++ = 0;
					*w &= -h;
				}
			}
	}
	
	// Invert all bits between low inclusive and high exclusive.
	template<size_t size>
	void BitSet<size>::flipRange(size_t low, size_t high) {
		ASSERT(low <= high && high <= size);
		if (low != high)
			if (nWords == 1)
				words[0] ^= (2u<<(high-1)) - (1u<<low);
			else {
				--high;
				uint32 *w = words + (low>>5);
				uint32 *wHigh = words + (high>>5);
				uint32 l = 1u << (low&31);
				uint32 h = 2u << (high&31);
				if (w == wHigh)
					*w ^= h - l;
				else {
					*w++ ^= -l;
					while (w != wHigh)
						*w++ ^= static_cast<uint32>(-1);
					*w ^= h - 1;
				}
			}
	}


//
// Input
//

	class LineReader {
		FILE *in;						// File from which currently reading
		bool crWasLast;					// True if a CR character was the last one read
	
	  public:
		explicit LineReader(FILE *in): in(in), crWasLast(false) {}

		size_t readLine(string &str);
		size_t readLine(String &wstr);
	};


//
// Output
//

	// Print the characters between begin and end to the given file.  These characters
	// may include nulls.
	size_t printChars(FILE *file, const char *begin, const char *end);

  #ifndef XP_MAC_MPW
	inline size_t printChars(FILE *file, const char *begin, const char *end)
		{ASSERT(end >= begin); return STD::fwrite(begin, 1, static_cast<size_t>(end - begin), file);}
  #endif


	// A Formatter is an abstract base class representing a simplified output stream.
	// One can print text to a Formatter by using << and the various global print... methods below.
	// Formatters accept both char and char16 text and convert as appropriate to their actual stream.
    class Formatter {
	  protected:
		virtual void printChar8(char ch);
		virtual void printChar16(char16 ch);
		virtual void printZStr8(const char *str);
		virtual void printStr8(const char *strBegin, const char *strEnd) = 0;
		virtual void printStr16(const char16 *strBegin, const char16 *strEnd) = 0;
		virtual void printString16(const String &s);
		virtual void printVFormat8(const char *format, va_list args);
	  public:

		Formatter &operator<<(char ch) {printChar8(ch); return *this;}
		Formatter &operator<<(char16 ch) {printChar16(ch); return *this;}
		Formatter &operator<<(const char *str) {printZStr8(str); return *this;}
		Formatter &operator<<(const String &s) {printString16(s); return *this;}
        Formatter &operator<<(uint32 i) {printFormat(*this, "%u", i); return *this;}

		friend void printString(Formatter &f, const char *strBegin, const char *strEnd) {f.printStr8(strBegin, strEnd);}
		friend void printString(Formatter &f, const char16 *strBegin, const char16 *strEnd) {f.printStr16(strBegin, strEnd);}
		friend void printFormat(Formatter &f, const char *format, ...) {va_list args; va_start(args, format); f.printVFormat8(format, args); va_end(args);}
    };
        
    void printNum(Formatter &f, uint32 i, int nDigits, char pad, const char *format);

    void printChar(Formatter &f, char ch, int count);
    void printChar(Formatter &f, char16 ch, int count);
    inline void printDec(Formatter &f, int32 i, int nDigits = 0, char pad = ' ') {printNum(f, (uint32)i, nDigits, pad, "%i");}
    inline void printDec(Formatter &f, uint32 i, int nDigits = 0, char pad = ' ') {printNum(f, i, nDigits, pad, "%u");}
    inline void printHex(Formatter &f, int32 i, int nDigits = 0, char pad = '0') {printNum(f, (uint32)i, nDigits, pad, "%X");}
    inline void printHex(Formatter &f, uint32 i, int nDigits = 0, char pad = '0') {printNum(f, i, nDigits, pad, "%X");}
    void printPtr(Formatter &f, void *p);


	// An AsciiFileFormatter is a Formatter that prints to a standard ASCII file or stream.
	// Characters with Unicode values of 256 or higher are converted to escape sequences.
	// Selected lower characters can also be converted to escape sequences; these are specified by
	// set bits in the BitSet passed to the constructor.
	class AsciiFileFormatter: public Formatter {
		FILE *file;
		BitSet<256> filter;				// Set of first 256 characters that are to be converted to escape sequences
		bool filterEmpty;				// True if filter passes all 256 characters
	  public:
		static BitSet<256> defaultFilter;// Default value of filter when not given in the constructor
		
		explicit AsciiFileFormatter(FILE *file, BitSet<256> *filter = 0);

	  private:
		bool filterChar(char ch) {return filter[static_cast<uchar>(ch)];}
		bool filterChar(char16 ch) {return char16Value(ch) >= 0x100 || filter[char16Value(ch)];}
	  protected:
		void printChar8(char ch);
		void printChar16(char16 ch);
		void printZStr8(const char *str);
		void printStr8(const char *strBegin, const char *strEnd);
		void printStr16(const char16 *strBegin, const char16 *strEnd);
	};

	extern AsciiFileFormatter stdOut;
	extern AsciiFileFormatter stdErr;


	// A StringFormatter is a Formatter that prints to a String.
	class StringFormatter: public Formatter {
		String s;

	  public:
		operator String &() {return s;}
		operator const String &() const {return s;}
		void clear() {JavaScript::clear(s);}
	  protected:
		void printChar8(char ch);
		void printChar16(char16 ch);
		void printZStr8(const char *str);
		void printStr8(const char *strBegin, const char *strEnd);
		void printStr16(const char16 *strBegin, const char16 *strEnd);
		void printString16(const String &str);
	};


//
// Formatted Output
//

	class PrettyPrinter: public Formatter {
	  public:
		STATIC_CONST(uint32, unlimitedLineWidth = 0x7FFFFFFF);
		class Region;
		class Indent;
		class Block;

	  private:
		STATIC_CONST(uint32, infiniteLength = 0x80000000);
		const uint32 lineWidth;			// Current maximum desired line width

		struct BlockInfo {
			uint32 margin;				// Saved margin before this block's beginning
			uint32 lastBreak;			// Saved lastBreak before this block's beginning
			bool fits;					// True if this entire block fits on one line
		};
		// Variables for the back end that prints to the destination
		Formatter &outputFormatter;		// Destination formatter on which the result should be printed
		uint32 outputPos;				// Number of characters printed on current output line
		uint32 lineNum;					// Serial number of current line
		uint32 lastBreak;				// Number of line just after the last break that occurred in this block
		uint32 margin;					// Current left margin in spaces
		ArrayBuffer<BlockInfo, 20> savedBlocks; // Stack of saved information about partially printed blocks

		// Variables for the front end that calculates block sizes
		struct Item: ListQueueEntry {
			enum Kind {text, blockBegin, indentBlockBegin, blockEnd, indent, linearBreak, fillBreak};

			const Kind kind;			// The kind of this text sequence
			bool lengthKnown;			// True if totalLength is known; always true for text, blockEnd, and indent Items
			uint32 length;				// Length of this text sequence, number of spaces for this break, or delta for indent or indentBlockBegin
			uint32 totalLength;			// Total length of this block (for blockBegin) or length of this break plus following clump (for breaks)
										// If lengthKnown is false, this is the serialPos of this Item instead of a length
			bool hasKind(Kind k) const {return kind == k;}
			
			explicit Item(Kind kind): kind(kind), lengthKnown(true) {}
			Item(Kind kind, uint32 length): kind(kind), lengthKnown(true), length(length) {}
			Item(Kind kind, uint32 length, uint32 beginSerialPos):
					kind(kind), lengthKnown(false), length(length), totalLength(beginSerialPos) {}
			
			void computeTotalLength(uint32 endSerialPos) {ASSERT(!lengthKnown); lengthKnown = true; totalLength = endSerialPos - totalLength;}
		};

	  #ifdef DEBUG
		Region *topRegion;				// Most deeply nested Region
	  #endif
		uint32 nNestedBlocks;			// Number of nested Blocks
		uint32 leftSerialPos;			// The difference rightSerialPos-leftSerialPos is always the number of characters that
		uint32 rightSerialPos;			//   would be output by printing activeItems if they all fit on one line;
										//   only the difference matters -- the absolute values are irrelevant and may wrap around 2^32.
		ArrayQueue<Item *, 20> itemStack; // Stack of enclosing nested Items whose lengths have not yet been determined
										// itemStack always has room for at least nNestedBlocks extra entries so that end Items may be added
										// without throwing an exception.
		Pool<Item> itemPool;			// Pool from which to allocate activeItems
		ListQueue<Item> activeItems;	// Queue of items left to be printed
		ArrayQueue<char16, 256> itemText; // Text of text items in activeItems, in the same order as in activeItems

	  public:
		static uint32 defaultLineWidth;	// Default for lineWidth if not given to the constructor

		explicit PrettyPrinter(Formatter &f, uint32 lineWidth = defaultLineWidth);
	  private:
	    PrettyPrinter(const PrettyPrinter&);	// No copy constructor
	    void operator=(const PrettyPrinter&);	// No assignment operator
	  public:
		~PrettyPrinter();
		
	  private:
		void outputBreak(bool sameLine, uint32 nSpaces);
		bool reduceLeftActiveItems(uint32 rightOffset);
		void reduceRightActiveItems();

		Item &beginIndent(int32 offset);
		void endIndent(Item &i);

		Item &beginBlock(Item::Kind kind, int32 offset);
		void endBlock(Item &i);

		void conditionalBreak(uint32 nSpaces, Item::Kind kind);

	  protected:
		void printStr8(const char *strBegin, const char *strEnd);
		void printStr16(const char16 *strBegin, const char16 *strEnd);
	  public:

		void requiredBreak();
		void linearBreak(uint32 nSpaces) {conditionalBreak(nSpaces, Item::linearBreak);}
		void linearBreak(uint32 nSpaces, bool required);
		void fillBreak(uint32 nSpaces) {conditionalBreak(nSpaces, Item::fillBreak);}
		
		void end();

		friend class Region;
		friend class Indent;
		friend class Block;

		class Region {
		  #ifdef DEBUG
			Region *next;				// Link to next most deeply nested Region
		  #endif
		  protected:
			PrettyPrinter &pp;

			Region(PrettyPrinter &pp): pp(pp) {DEBUG_ONLY(next = pp.topRegion; pp.topRegion = this;)}
		  private:
		    Region(const Region&);			// No copy constructor
		    void operator=(const Region&);	// No assignment operator
		  protected:
		  #ifdef DEBUG
			~Region() {pp.topRegion = next;}
		  #endif
		};
		
		// Use an Indent object to temporarily indent a PrettyPrinter by the offset given to the Indent's constructor.
		// The PrettyPrinter's margin is set back to its original value when the Indent object is destroyed.
		// Using an Indent object is exception-safe; no matter how control leaves an Indent scope, the indent is undone.
		// Scopes of Indent and Block objects must be properly nested.
		class Indent: public Region {
			Item &endItem;				// The Item returned by beginIndent
		  public:
			Indent(PrettyPrinter &pp, int32 offset): Region(pp), endItem(pp.beginIndent(offset)) {}
			~Indent() {pp.endIndent(endItem);}
		};
		
		// Use a Block object to temporarily enter a PrettyPrinter block.  If an offset is provided, line breaks inside
		// the block are indented by that offset relative to the existing indent; otherwise, line breaks inside the block
		// are indented to the current output position.  The block lasts until the Block object is destroyed.
		// Scopes of Indent and Block objects must be properly nested.
		class Block: public Region {
			Item &endItem;				// The Item returned by beginBlock
		  public:
			explicit Block(PrettyPrinter &pp): Region(pp), endItem(pp.beginBlock(Item::blockBegin, 0)) {}
			Block(PrettyPrinter &pp, int32 offset): Region(pp), endItem(pp.beginBlock(Item::indentBlockBegin, offset)) {}
			~Block() {pp.endBlock(endItem);}
		};
	};


//
// Exceptions
//

	// A JavaScript exception (other than out-of-memory, for which we use the standard C++
	// exception bad_alloc).
	struct Exception {
		enum Kind {
			syntaxError,
			stackOverflow
		};
		
		Kind kind;						// The exception's kind
		String message;					// The detailed message
		String sourceFile;				// A description of the source code that caused the error
		uint32 lineNum;					// Number of line that caused the error
		uint32 charNum;					// Character offset within the line that caused the error
		uint32 pos;						// Offset within the input of the error
		String sourceLine;				// The text of the source line

		Exception(Kind kind, const String &message): kind(kind), message(message), lineNum(0), charNum(0) {}
		Exception(Kind kind, const String &message, const String &sourceFile, uint32 lineNum, uint32 charNum, uint32 pos,
				const String &sourceLine):
			kind(kind), message(message), sourceFile(sourceFile), lineNum(lineNum), charNum(charNum), pos(pos), sourceLine(sourceLine) {}
		Exception(Kind kind, const String &message, const String &sourceFile, uint32 lineNum, uint32 charNum, uint32 pos,
				const char16 *sourceLineBegin, const char16 *sourceLineEnd):
			kind(kind), message(message), sourceFile(sourceFile), lineNum(lineNum), charNum(charNum), pos(pos),
			sourceLine(sourceLineBegin, sourceLineEnd) {}

		bool hasKind(Kind k) const {return kind == k;}
		const char *kindString() const;
		String fullMessage() const;
	};


	// Throw a stackOverflow exception if the execution stack has gotten too large.
	inline void checkStackSize() {}
}


inline void *operator new(size_t size, JavaScript::Arena &arena) {return arena.allocate(size);}
#ifndef _WIN32		// Microsoft Visual C++ 6.0 bug: new and new[] aren't distinguished
 inline void *operator new[](size_t size, JavaScript::Arena &arena) {return arena.allocate(size);}
#endif

#ifndef __MWERKS__	// Metrowerks 5.3 bug: Two-argument delete isn't supported yet
 // Global delete operators.  These are only called in the rare cases that a constructor throws an exception
 // and has to undo an operator new.  An explicit delete statement will never invoke these.
 inline void operator delete(void *, JavaScript::Arena &) {}
 #ifndef _WIN32		// Microsoft Visual C++ 6.0 bug: new and new[] aren't distinguished
  inline void operator delete[](void *, JavaScript::Arena &) {}
 #endif
#endif

template <typename T>
inline void *operator new(size_t DEBUG_ONLY(size), JavaScript::Pool<T> &pool) {ASSERT(size == sizeof(T)); return pool.allocate();}
#ifndef __MWERKS__	// Metrowerks 5.3 bug: Two-argument delete isn't supported yet
 template <typename T>
 inline void operator delete(void *t, JavaScript::Pool<T> &pool) {pool.deallocate(t);}
#endif
#endif