[bigint/bigint.git] / NumberlikeArray.hh

/*
* Matt McCutchen's Big Integer Library
* http://mysite.verizon.net/mccutchen/bigint/
*/

/*
* This mechanism prevents files from being included twice.
* Each file gets its own `id' (here `NUMBERLIKEARRAY').
* When `#include'd, this file checks whether its `id' has
* already been flagged.  If not, it flags the `id' and
* loads the declarations.
*/
#ifndef NUMBERLIKEARRAY
#define NUMBERLIKEARRAY

// An essential memory-management constant.
// I wish this were built into C++ just as it is in Java.
#ifndef NULL
#define NULL 0
#endif

/*
* A NumberlikeArray<Block> object holds a dynamically
* allocated array of Blocks.  It provides certain basic
* memory management features needed by both BigUnsigned
* and BigUnsignedInABase, which are both derived from it.
*
* NumberlikeArray provides no information hiding, so make
* sure you know what you are doing if you use it directly.
* Classes derived from it will probably wish to pass on
* some members of NumberlikeArray to their clients while
* keeping some safe for themselves.  These classes should
* use protected inheritance and manually make some members
* public with declarations like this:
*
* public:
*     NumberlikeArray< whatever >::getLength;
*/

/*debug*/
#include <iostream>

template <class Blk>
class NumberlikeArray {
	public:
	
	typedef unsigned int Index; // Type for the index of a block in the array
	
	// FIELDS
	Index cap; // The current allocated capacity of this NumberlikeArray (in blocks)
	Index len; // The actual length of the value stored in this NumberlikeArray (in blocks)
	Blk *blk2; // Dynamically allocated array of the blocks
	
	static Blk x; // trash that [] can return for out-of-range requests
	
	void dump() const {
		std::cout << "Dumping NumberlikeArray @ " << (void *)(this) << '\n';
		std::cout << "Length " << (len) << ", capacity " << (cap) << '\n';
		for (unsigned int i = 0; i < len; i++) {
			std::cout << "Block " << i << ":" << blk2[i] << '\n';
		}
	}
	
	struct BoundsCheckingBlk {
		const NumberlikeArray *na;
		BoundsCheckingBlk(NumberlikeArray *na) {
			this->na = na;
		}
		Blk & operator [](Index index) const {
			if (index >= na->len) {
				std::cout << "== Out-of-bounds access to block " << index << ".  Affected NumberlikeArray: ==\n";
				na->dump();
				std::cout << "== End of dump. ==" << std::endl;
				return x;
			} else
				return na->blk2[index];
		} // dangerous because it allows ``always writable'', but OK for now
		/*const Blk & operator [](Index index) const {
			if (index >= na->len)
				std::cout << "OUT OF BOUNDS!  Length " << (na->len) << ", accessed " << index << std::endl;
			else
				return na->blk[index];
		}*/
		/*operator Blk * () {
			return na->blk2;
		}*/
	};
	
	BoundsCheckingBlk blk;
	
	/*
	* Change made on 2005.01.06:
	*
	* If a zero-length NumberlikeArray is desired, no array is actually allocated.
	* Instead, `blk' is set to `NULL', and `cap' and `len' are zero as usual.
	*
	* `blk' is never dereferenced if the array has zero length.  Furthermore,
	* `delete NULL;' does nothing and causes no error. Therefore, we can use
	* `NULL' as if it were a zero-length array from `new'.
	*
	* This is a great convenience because the only code that need be changed
	* is the array allocation code.  All other code will still work file.
	*/
	
	// MANAGEMENT
	NumberlikeArray(Index c) : cap(c), len(0), blk(this) { // Creates a NumberlikeArray with a capacity
		blk2 = (cap > 0) ? (new Blk[cap]) : NULL;
	}
	void allocate(Index c); // Ensures the array has at least the indicated capacity, maybe discarding contents
	void allocateAndCopy(Index c); // Ensures the array has at least the indicated capacity, preserving its contents
	
	/*
	* Default constructor.
	*
	* If a class derived from NumberlikeArray knows at initializer time what size array
	* it wants, it can call the first constructor listed above in an initializer.
	*
	* Otherwise, this default constructor will be implicitly invoked, pointing `blk' to
	* `NULL', a fake zero-length block array.  The derived class can allocate the desired
	* array itself and overwrite `blk'; it need not `delete [] blk' first.
	*
	* This change fixes a memory leak reported by Milan Tomic on 2005.01.06.
	* Integer-type-to-BigUnsigned (and BigInteger) conversion constructors have always
	* allocated their own array of length 0 or 1 after seeing whether the input is zero.
	* But when the NumberlikeArray transition occurred, these constructors contained an
	* implicit initializer call to the old NumberlikeArray default constructor, which
	* created a real `new'-allocated zero-length array.  This array would then be lost,
	* causing a small but annoying memory leak.
	*/
	NumberlikeArray() : cap(0), len(0), blk(this) {
		blk2 = NULL;
	}
	NumberlikeArray(const NumberlikeArray<Blk> &x); // Copy constructor
	void operator=(const NumberlikeArray<Blk> &x); // Assignment operator
	NumberlikeArray(const Blk *b, Index l); // Constructor from an array of blocks
	~NumberlikeArray() { // Destructor
		delete [] blk2; // Does nothing and causes no error if `blk' is null.
	}
	
	// PICKING APART
	// These accessors can be used to get the pieces of the value
	Index getCapacity() const { return cap; }
	Index getLength() const { return len; }
	Blk getBlock(Index i) const { return blk[i]; };
	bool isEmpty() const { return len == 0; }
	
	// Equality comparison: checks if arrays have same length and matching values
	// Derived classes may wish to override these if differing arrays can
	// sometimes be considered equivalent.
	bool operator ==(const NumberlikeArray<Blk> &x) const;
	bool operator !=(const NumberlikeArray<Blk> &x) const;
	
};

/*
* BELOW THIS POINT are template definitions; above are declarations.
*
* Definitions would ordinarily belong in a file NumberlikeArray.cc so that they would
* be compiled once into NumberlikeArray.o and then linked.
*
* However, because of the way templates are usually implemented,
* template ``definitions'' are treated as declarations by the compiler.
* When someone uses an instance of the template, definitions are generated,
* and the linker is smart enough to toss duplicate definitions for the same
* instance generated by different files.
*
* Thus, the template ``definitions'' for NumberlikeArray must appear in this header file
* so other files including NumberlikeArray will be able to generate real definitions.
*/

template <class Blk>
Blk NumberlikeArray<Blk>::x = 0;

// MANAGEMENT

// This routine is called to ensure the array is at least a
// certain size before another value is written into it.
template <class Blk>
void NumberlikeArray<Blk>::allocate(Index c) {
	// If the requested capacity is more than the current capacity...
	if (c > cap) {
		// Delete the old number array
		delete [] blk2;
		// Allocate the new array
		cap = c;
		blk2 = new Blk[cap];
	}
}

// This routine is called to ensure the array is at least a
// certain size without losing its contents.
template <class Blk>
void NumberlikeArray<Blk>::allocateAndCopy(Index c) {
	// If the requested capacity is more than the current capacity...
	if (c > cap) {
		Blk *oldBlk = blk2;
		// Allocate the new number array
		cap = c;
		blk2 = new Blk[cap];
		// Copy number blocks
		Index i;
		for (i = 0; i < len; i++)
			blk[i] = oldBlk[i];
		// Delete the old array
		delete [] oldBlk;
	}
}

// Copy constructor
template <class Blk>
NumberlikeArray<Blk>::NumberlikeArray(const NumberlikeArray<Blk> &x) : len(x.len), blk(this) {
	// Create array
	cap = len;
	blk2 = new Blk[cap];
	// Copy blocks
	Index i;
	for (i = 0; i < len; i++)
		blk[i] = x.blk[i];
}

// Assignment operator
template <class Blk>
void NumberlikeArray<Blk>::operator=(const NumberlikeArray<Blk> &x) {
	// Calls like a = a have no effect
	if (this == &x)
		return;
	// Copy length
	len = x.len;
	// Expand array if necessary
	allocate(len);
	// Copy number blocks
	Index i;
	for (i = 0; i < len; i++)
		blk[i] = x.blk[i];
}

// Constructor from an array of blocks
template <class Blk>
NumberlikeArray<Blk>::NumberlikeArray(const Blk *b, Index l) : cap(l), len(l), blk(this) {
	// Create array
	blk2 = new Blk[cap];
	// Copy blocks
	Index i;
	for (i = 0; i < len; i++)
		blk[i] = b[i];
}


// EQUALITY TEST
// This uses == to compare Blks for equality.
// Therefore, Blks must have an == operator with the desired semantics.
template <class Blk>
bool NumberlikeArray<Blk>::operator ==(const NumberlikeArray<Blk> &x) const {
	// Different lengths imply different objects.
	if (len != x.len)
		return false;
	else {
		// Compare matching blocks one by one.
		Index i;
		for (i = 0; i < len; i++)
			if (blk[i] != x.blk[i])
				return false;
		// If no blocks differed, the objects are equal.
		return true;
	}
}

#endif
Commit	Line	Data
05780f4b MM	1	/*
	2	* Matt McCutchen's Big Integer Library
	3	* http://mysite.verizon.net/mccutchen/bigint/
	4	*/
	5
b3fe29df MM	6	/*
	7	* This mechanism prevents files from being included twice.
	8	* Each file gets its own `id' (here `NUMBERLIKEARRAY').
	9	* When `#include'd, this file checks whether its `id' has
	10	* already been flagged. If not, it flags the `id' and
	11	* loads the declarations.
	12	*/
05780f4b MM	13	#ifndef NUMBERLIKEARRAY
	14	#define NUMBERLIKEARRAY
	15
b3fe29df MM	16	// An essential memory-management constant.
	17	// I wish this were built into C++ just as it is in Java.
	18	#ifndef NULL
	19	#define NULL 0
	20	#endif
	21
05780f4b MM	22	/*
	23	* A NumberlikeArray<Block> object holds a dynamically
	24	* allocated array of Blocks. It provides certain basic
	25	* memory management features needed by both BigUnsigned
	26	* and BigUnsignedInABase, which are both derived from it.
	27	*
	28	* NumberlikeArray provides no information hiding, so make
	29	* sure you know what you are doing if you use it directly.
	30	* Classes derived from it will probably wish to pass on
	31	* some members of NumberlikeArray to their clients while
	32	* keeping some safe for themselves. These classes should
	33	* use protected inheritance and manually make some members
	34	* public with declarations like this:
	35	*
	36	* public:
	37	* NumberlikeArray< whatever >::getLength;
	38	*/
	39
2f145f11 MM	40	/debug/
	41	#include <iostream>
	42
05780f4b MM	43	template <class Blk>
	44	class NumberlikeArray {
	45	public:
	46
	47	typedef unsigned int Index; // Type for the index of a block in the array
	48
	49	// FIELDS
	50	Index cap; // The current allocated capacity of this NumberlikeArray (in blocks)
	51	Index len; // The actual length of the value stored in this NumberlikeArray (in blocks)
2f145f11 MM	52	Blk *blk2; // Dynamically allocated array of the blocks
	53
	54	static Blk x; // trash that [] can return for out-of-range requests
	55
	56	void dump() const {
	57	std::cout << "Dumping NumberlikeArray @ " << (void *)(this) << '\n';
	58	std::cout << "Length " << (len) << ", capacity " << (cap) << '\n';
	59	for (unsigned int i = 0; i < len; i++) {
	60	std::cout << "Block " << i << ":" << blk2[i] << '\n';
	61	}
	62	}
	63
	64	struct BoundsCheckingBlk {
	65	const NumberlikeArray *na;
	66	BoundsCheckingBlk(NumberlikeArray *na) {
	67	this->na = na;
	68	}
	69	Blk & operator [](Index index) const {
	70	if (index >= na->len) {
	71	std::cout << "== Out-of-bounds access to block " << index << ". Affected NumberlikeArray: ==\n";
	72	na->dump();
	73	std::cout << "== End of dump. ==" << std::endl;
	74	return x;
	75	} else
	76	return na->blk2[index];
	77	} // dangerous because it allows ``always writable'', but OK for now
	78	/*const Blk & operator [](Index index) const {
	79	if (index >= na->len)
	80	std::cout << "OUT OF BOUNDS! Length " << (na->len) << ", accessed " << index << std::endl;
	81	else
	82	return na->blk[index];
	83	}*/
	84	/operator Blk () {
	85	return na->blk2;
	86	}*/
	87	};
	88
	89	BoundsCheckingBlk blk;
	90
b3fe29df MM	91	/*
	92	* Change made on 2005.01.06:
	93	*
	94	* If a zero-length NumberlikeArray is desired, no array is actually allocated.
	95	* Instead, `blk' is set to `NULL', and `cap' and `len' are zero as usual.
	96	*
	97	* `blk' is never dereferenced if the array has zero length. Furthermore,
	98	* `delete NULL;' does nothing and causes no error. Therefore, we can use
	99	* `NULL' as if it were a zero-length array from `new'.
	100	*
	101	* This is a great convenience because the only code that need be changed
	102	* is the array allocation code. All other code will still work file.
	103	*/
05780f4b MM	104
05780f4b MM	105	// MANAGEMENT
2f145f11 MM	106	NumberlikeArray(Index c) : cap(c), len(0), blk(this) { // Creates a NumberlikeArray with a capacity
2f145f11 MM	107	blk2 = (cap > 0) ? (new Blk[cap]) : NULL;
05780f4b MM	108	}
	109	void allocate(Index c); // Ensures the array has at least the indicated capacity, maybe discarding contents
	110	void allocateAndCopy(Index c); // Ensures the array has at least the indicated capacity, preserving its contents
	111
b3fe29df MM	112	/*
	113	* Default constructor.
	114	*
	115	* If a class derived from NumberlikeArray knows at initializer time what size array
	116	* it wants, it can call the first constructor listed above in an initializer.
	117	*
	118	* Otherwise, this default constructor will be implicitly invoked, pointing `blk' to
	119	* `NULL', a fake zero-length block array. The derived class can allocate the desired
	120	* array itself and overwrite `blk'; it need not `delete [] blk' first.
	121	*
	122	* This change fixes a memory leak reported by Milan Tomic on 2005.01.06.
	123	* Integer-type-to-BigUnsigned (and BigInteger) conversion constructors have always
	124	* allocated their own array of length 0 or 1 after seeing whether the input is zero.
	125	* But when the NumberlikeArray transition occurred, these constructors contained an
	126	* implicit initializer call to the old NumberlikeArray default constructor, which
	127	* created a real `new'-allocated zero-length array. This array would then be lost,
	128	* causing a small but annoying memory leak.
	129	*/
2f145f11 MM	130	NumberlikeArray() : cap(0), len(0), blk(this) {
2f145f11 MM	131	blk2 = NULL;
05780f4b MM	132	}
	133	NumberlikeArray(const NumberlikeArray<Blk> &x); // Copy constructor
	134	void operator=(const NumberlikeArray<Blk> &x); // Assignment operator
	135	NumberlikeArray(const Blk *b, Index l); // Constructor from an array of blocks
	136	~NumberlikeArray() { // Destructor
2f145f11	137	delete [] blk2; // Does nothing and causes no error if `blk' is null.
05780f4b MM	138	}
	139
	140	// PICKING APART
	141	// These accessors can be used to get the pieces of the value
	142	Index getCapacity() const { return cap; }
	143	Index getLength() const { return len; }
	144	Blk getBlock(Index i) const { return blk[i]; };
	145	bool isEmpty() const { return len == 0; }
	146
	147	// Equality comparison: checks if arrays have same length and matching values
	148	// Derived classes may wish to override these if differing arrays can
	149	// sometimes be considered equivalent.
	150	bool operator ==(const NumberlikeArray<Blk> &x) const;
	151	bool operator !=(const NumberlikeArray<Blk> &x) const;
	152
	153	};
	154
	155	/*
	156	* BELOW THIS POINT are template definitions; above are declarations.
	157	*
	158	* Definitions would ordinarily belong in a file NumberlikeArray.cc so that they would
	159	* be compiled once into NumberlikeArray.o and then linked.
	160	*
	161	* However, because of the way templates are usually implemented,
	162	* template ``definitions'' are treated as declarations by the compiler.
	163	* When someone uses an instance of the template, definitions are generated,
	164	* and the linker is smart enough to toss duplicate definitions for the same
	165	* instance generated by different files.
	166	*
	167	* Thus, the template ``definitions'' for NumberlikeArray must appear in this header file
	168	* so other files including NumberlikeArray will be able to generate real definitions.
	169	*/
	170
2f145f11 MM	171	template <class Blk>
	172	Blk NumberlikeArray<Blk>::x = 0;
	173
05780f4b MM	174	// MANAGEMENT
	175
	176	// This routine is called to ensure the array is at least a
	177	// certain size before another value is written into it.
	178	template <class Blk>
	179	void NumberlikeArray<Blk>::allocate(Index c) {
	180	// If the requested capacity is more than the current capacity...
	181	if (c > cap) {
	182	// Delete the old number array
2f145f11	183	delete [] blk2;
05780f4b MM	184	// Allocate the new array
05780f4b MM	185	cap = c;
2f145f11	186	blk2 = new Blk[cap];
05780f4b MM	187	}
	188	}
	189
	190	// This routine is called to ensure the array is at least a
	191	// certain size without losing its contents.
	192	template <class Blk>
	193	void NumberlikeArray<Blk>::allocateAndCopy(Index c) {
	194	// If the requested capacity is more than the current capacity...
	195	if (c > cap) {
2f145f11	196	Blk *oldBlk = blk2;
05780f4b MM	197	// Allocate the new number array
05780f4b MM	198	cap = c;
2f145f11	199	blk2 = new Blk[cap];
05780f4b MM	200	// Copy number blocks
	201	Index i;
	202	for (i = 0; i < len; i++)
	203	blk[i] = oldBlk[i];
	204	// Delete the old array
	205	delete [] oldBlk;
	206	}
	207	}
	208
	209	// Copy constructor
	210	template <class Blk>
2f145f11	211	NumberlikeArray<Blk>::NumberlikeArray(const NumberlikeArray<Blk> &x) : len(x.len), blk(this) {
05780f4b MM	212	// Create array
05780f4b MM	213	cap = len;
2f145f11	214	blk2 = new Blk[cap];
05780f4b MM	215	// Copy blocks
	216	Index i;
	217	for (i = 0; i < len; i++)
	218	blk[i] = x.blk[i];
	219	}
	220
	221	// Assignment operator
	222	template <class Blk>
	223	void NumberlikeArray<Blk>::operator=(const NumberlikeArray<Blk> &x) {
	224	// Calls like a = a have no effect
	225	if (this == &x)
	226	return;
	227	// Copy length
	228	len = x.len;
	229	// Expand array if necessary
	230	allocate(len);
	231	// Copy number blocks
	232	Index i;
	233	for (i = 0; i < len; i++)
	234	blk[i] = x.blk[i];
	235	}
	236
	237	// Constructor from an array of blocks
	238	template <class Blk>
2f145f11	239	NumberlikeArray<Blk>::NumberlikeArray(const Blk *b, Index l) : cap(l), len(l), blk(this) {
05780f4b	240	// Create array
2f145f11	241	blk2 = new Blk[cap];
05780f4b MM	242	// Copy blocks
	243	Index i;
	244	for (i = 0; i < len; i++)
	245	blk[i] = b[i];
	246	}
	247
	248
	249	// EQUALITY TEST
	250	// This uses == to compare Blks for equality.
	251	// Therefore, Blks must have an == operator with the desired semantics.
	252	template <class Blk>
	253	bool NumberlikeArray<Blk>::operator ==(const NumberlikeArray<Blk> &x) const {
	254	// Different lengths imply different objects.
	255	if (len != x.len)
	256	return false;
	257	else {
	258	// Compare matching blocks one by one.
	259	Index i;
	260	for (i = 0; i < len; i++)
	261	if (blk[i] != x.blk[i])
	262	return false;
	263	// If no blocks differed, the objects are equal.
	264	return true;
	265	}
	266	}
	267
	268	#endif