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authorBo Xu <bo_xu@foxitsoftware.com>2014-12-02 13:06:22 -0800
committerBo Xu <bo_xu@foxitsoftware.com>2014-12-02 13:06:22 -0800
commit7504b3d87d6143661746d85c3c3e4052939b4e52 (patch)
tree3baa8695a001c3226719409b666db31c3153f039 /third_party/bigint/NumberlikeArray.hh
parent4643533ca3dabe945fd174caf892a3ccb6cf2fd6 (diff)
downloadpdfium-7504b3d87d6143661746d85c3c3e4052939b4e52.tar.xz
Initial check in of big integer library, v2010.04.30
R=tsepez@chromium.org Review URL: https://codereview.chromium.org/773443004
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+#ifndef NUMBERLIKEARRAY_H
+#define NUMBERLIKEARRAY_H
+
+// Make sure we have NULL.
+#ifndef NULL
+#define NULL 0
+#endif
+
+/* A NumberlikeArray<Blk> object holds a heap-allocated array of Blk with a
+ * length and a capacity and provides basic memory management features.
+ * BigUnsigned and BigUnsignedInABase both subclass it.
+ *
+ * NumberlikeArray provides no information hiding. Subclasses should use
+ * nonpublic inheritance and manually expose members as desired using
+ * declarations like this:
+ *
+ * public:
+ * NumberlikeArray< the-type-argument >::getLength;
+ */
+template <class Blk>
+class NumberlikeArray {
+public:
+
+ // Type for the index of a block in the array
+ typedef unsigned int Index;
+ // The number of bits in a block, defined below.
+ static const unsigned int N;
+
+ // The current allocated capacity of this NumberlikeArray (in blocks)
+ Index cap;
+ // The actual length of the value stored in this NumberlikeArray (in blocks)
+ Index len;
+ // Heap-allocated array of the blocks (can be NULL if len == 0)
+ Blk *blk;
+
+ // Constructs a ``zero'' NumberlikeArray with the given capacity.
+ NumberlikeArray(Index c) : cap(c), len(0) {
+ blk = (cap > 0) ? (new Blk[cap]) : NULL;
+ }
+
+ /* Constructs a zero NumberlikeArray without allocating a backing array.
+ * A subclass that doesn't know the needed capacity at initialization
+ * time can use this constructor and then overwrite blk without first
+ * deleting it. */
+ NumberlikeArray() : cap(0), len(0) {
+ blk = NULL;
+ }
+
+ // Destructor. Note that `delete NULL' is a no-op.
+ ~NumberlikeArray() {
+ delete [] blk;
+ }
+
+ /* Ensures that the array has at least the requested capacity; may
+ * destroy the contents. */
+ void allocate(Index c);
+
+ /* Ensures that the array has at least the requested capacity; does not
+ * destroy the contents. */
+ void allocateAndCopy(Index c);
+
+ // Copy constructor
+ NumberlikeArray(const NumberlikeArray<Blk> &x);
+
+ // Assignment operator
+ void operator=(const NumberlikeArray<Blk> &x);
+
+ // Constructor that copies from a given array of blocks
+ NumberlikeArray(const Blk *b, Index blen);
+
+ // ACCESSORS
+ 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 both objects have the same length and
+ * equal (==) array elements to that length. Subclasses may wish to
+ * override. */
+ bool operator ==(const NumberlikeArray<Blk> &x) const;
+
+ bool operator !=(const NumberlikeArray<Blk> &x) const {
+ return !operator ==(x);
+ }
+};
+
+/* BEGIN TEMPLATE DEFINITIONS. They are present here so that source files that
+ * include this header file can generate the necessary real definitions. */
+
+template <class Blk>
+const unsigned int NumberlikeArray<Blk>::N = 8 * sizeof(Blk);
+
+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 [] blk;
+ // Allocate the new array
+ cap = c;
+ blk = new Blk[cap];
+ }
+}
+
+template <class Blk>
+void NumberlikeArray<Blk>::allocateAndCopy(Index c) {
+ // If the requested capacity is more than the current capacity...
+ if (c > cap) {
+ Blk *oldBlk = blk;
+ // Allocate the new number array
+ cap = c;
+ blk = new Blk[cap];
+ // Copy number blocks
+ Index i;
+ for (i = 0; i < len; i++)
+ blk[i] = oldBlk[i];
+ // Delete the old array
+ delete [] oldBlk;
+ }
+}
+
+template <class Blk>
+NumberlikeArray<Blk>::NumberlikeArray(const NumberlikeArray<Blk> &x)
+ : len(x.len) {
+ // Create array
+ cap = len;
+ blk = new Blk[cap];
+ // Copy blocks
+ Index i;
+ for (i = 0; i < len; i++)
+ blk[i] = x.blk[i];
+}
+
+template <class Blk>
+void NumberlikeArray<Blk>::operator=(const NumberlikeArray<Blk> &x) {
+ /* Calls like a = a have no effect; catch them before the aliasing
+ * causes a problem */
+ 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];
+}
+
+template <class Blk>
+NumberlikeArray<Blk>::NumberlikeArray(const Blk *b, Index blen)
+ : cap(blen), len(blen) {
+ // Create array
+ blk = new Blk[cap];
+ // Copy blocks
+ Index i;
+ for (i = 0; i < len; i++)
+ blk[i] = b[i];
+}
+
+template <class Blk>
+bool NumberlikeArray<Blk>::operator ==(const NumberlikeArray<Blk> &x) const {
+ if (len != x.len)
+ // Definitely unequal.
+ return false;
+ else {
+ // Compare corresponding blocks one by one.
+ Index i;
+ for (i = 0; i < len; i++)
+ if (blk[i] != x.blk[i])
+ return false;
+ // No blocks differed, so the objects are equal.
+ return true;
+ }
+}
+
+#endif