/*
-* Matt McCutchen's Big Integer Library
-*/
-
-/*
-* 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
+ * 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_H
+#define NUMBERLIKEARRAY_H
// An essential memory-management constant.
// I wish this were built into C++ just as it is in Java.
#endif
/*
-* A NumberlikeArray<Blk> object holds a dynamically
-* allocated array of Blk. 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;
-*/
+ * A NumberlikeArray<Blk> object holds a dynamically
+ * allocated array of Blk. 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;
+ */
template <class Blk>
class NumberlikeArray {
public:
-
+
typedef unsigned int Index; // Type for the index of a block in the array
static const unsigned int N; // The number of bits in a block, defined below.
-
+
// 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 *blk; // Dynamically allocated array of the blocks
-
+
/*
- * 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 fine.
- */
-
+ * 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 fine.
+ */
+
// MANAGEMENT
NumberlikeArray(Index c) : cap(c), len(0) { // Creates a NumberlikeArray with a capacity
blk = (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.
- */
+ * 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 = NULL;
}
~NumberlikeArray() { // Destructor
delete [] blk; // 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 { return !operator ==(x); }
-
+
};
/*
-* =================================
-* 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.
-*/
+ * =================================
+ * 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>
const unsigned int NumberlikeArray<Blk>::N = 8 * sizeof(Blk);
Matt McCutchen's Web Site / bigint / bigint.git / blobdiff