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b3fe29df | 1 | /* |
6e1e0f2f MM |
2 | * This mechanism prevents files from being included twice. |
3 | * Each file gets its own `id' (here `NUMBERLIKEARRAY'). | |
4 | * When `#include'd, this file checks whether its `id' has | |
5 | * already been flagged. If not, it flags the `id' and | |
6 | * loads the declarations. | |
7 | */ | |
05780f4b MM |
8 | #ifndef NUMBERLIKEARRAY |
9 | #define NUMBERLIKEARRAY | |
10 | ||
b3fe29df MM |
11 | // An essential memory-management constant. |
12 | // I wish this were built into C++ just as it is in Java. | |
13 | #ifndef NULL | |
14 | #define NULL 0 | |
15 | #endif | |
16 | ||
05780f4b | 17 | /* |
6e1e0f2f MM |
18 | * A NumberlikeArray<Blk> object holds a dynamically |
19 | * allocated array of Blk. It provides certain basic | |
20 | * memory management features needed by both BigUnsigned | |
21 | * and BigUnsignedInABase, which are both derived from it. | |
22 | * | |
23 | * NumberlikeArray provides no information hiding, so make | |
24 | * sure you know what you are doing if you use it directly. | |
25 | * Classes derived from it will probably wish to pass on | |
26 | * some members of NumberlikeArray to their clients while | |
27 | * keeping some safe for themselves. These classes should | |
28 | * use protected inheritance and manually make some members | |
29 | * public with declarations like this: | |
30 | * | |
31 | * public: | |
32 | * NumberlikeArray< whatever >::getLength; | |
33 | */ | |
05780f4b MM |
34 | |
35 | template <class Blk> | |
36 | class NumberlikeArray { | |
37 | public: | |
5ff40cf5 | 38 | |
05780f4b | 39 | typedef unsigned int Index; // Type for the index of a block in the array |
4efbb076 | 40 | static const unsigned int N; // The number of bits in a block, defined below. |
5ff40cf5 | 41 | |
05780f4b MM |
42 | // FIELDS |
43 | Index cap; // The current allocated capacity of this NumberlikeArray (in blocks) | |
44 | Index len; // The actual length of the value stored in this NumberlikeArray (in blocks) | |
a8b42b68 | 45 | Blk *blk; // Dynamically allocated array of the blocks |
5ff40cf5 | 46 | |
b3fe29df | 47 | /* |
6e1e0f2f MM |
48 | * Change made on 2005.01.06: |
49 | * | |
50 | * If a zero-length NumberlikeArray is desired, no array is actually allocated. | |
51 | * Instead, `blk' is set to `NULL', and `cap' and `len' are zero as usual. | |
52 | * | |
53 | * `blk' is never dereferenced if the array has zero length. Furthermore, | |
54 | * `delete NULL;' does nothing and causes no error. Therefore, we can use | |
55 | * `NULL' as if it were a zero-length array from `new'. | |
56 | * | |
57 | * This is a great convenience because the only code that need be changed | |
58 | * is the array allocation code. All other code will still work fine. | |
59 | */ | |
5ff40cf5 | 60 | |
05780f4b | 61 | // MANAGEMENT |
a8b42b68 MM |
62 | NumberlikeArray(Index c) : cap(c), len(0) { // Creates a NumberlikeArray with a capacity |
63 | blk = (cap > 0) ? (new Blk[cap]) : NULL; | |
05780f4b MM |
64 | } |
65 | void allocate(Index c); // Ensures the array has at least the indicated capacity, maybe discarding contents | |
66 | void allocateAndCopy(Index c); // Ensures the array has at least the indicated capacity, preserving its contents | |
5ff40cf5 | 67 | |
b3fe29df | 68 | /* |
6e1e0f2f MM |
69 | * Default constructor. |
70 | * | |
71 | * If a class derived from NumberlikeArray knows at initializer time what size array | |
72 | * it wants, it can call the first constructor listed above in an initializer. | |
73 | * | |
74 | * Otherwise, this default constructor will be implicitly invoked, pointing `blk' to | |
75 | * `NULL', a fake zero-length block array. The derived class can allocate the desired | |
76 | * array itself and overwrite `blk'; it need not `delete [] blk' first. | |
77 | * | |
78 | * This change fixes a memory leak reported by Milan Tomic on 2005.01.06. | |
79 | * Integer-type-to-BigUnsigned (and BigInteger) conversion constructors have always | |
80 | * allocated their own array of length 0 or 1 after seeing whether the input is zero. | |
81 | * But when the NumberlikeArray transition occurred, these constructors contained an | |
82 | * implicit initializer call to the old NumberlikeArray default constructor, which | |
83 | * created a real `new'-allocated zero-length array. This array would then be lost, | |
84 | * causing a small but annoying memory leak. | |
85 | */ | |
a8b42b68 MM |
86 | NumberlikeArray() : cap(0), len(0) { |
87 | blk = NULL; | |
05780f4b MM |
88 | } |
89 | NumberlikeArray(const NumberlikeArray<Blk> &x); // Copy constructor | |
90 | void operator=(const NumberlikeArray<Blk> &x); // Assignment operator | |
91 | NumberlikeArray(const Blk *b, Index l); // Constructor from an array of blocks | |
92 | ~NumberlikeArray() { // Destructor | |
a8b42b68 | 93 | delete [] blk; // Does nothing and causes no error if `blk' is null. |
05780f4b | 94 | } |
5ff40cf5 | 95 | |
05780f4b MM |
96 | // PICKING APART |
97 | // These accessors can be used to get the pieces of the value | |
98 | Index getCapacity() const { return cap; } | |
99 | Index getLength() const { return len; } | |
100 | Blk getBlock(Index i) const { return blk[i]; }; | |
101 | bool isEmpty() const { return len == 0; } | |
5ff40cf5 | 102 | |
05780f4b MM |
103 | // Equality comparison: checks if arrays have same length and matching values |
104 | // Derived classes may wish to override these if differing arrays can | |
105 | // sometimes be considered equivalent. | |
106 | bool operator ==(const NumberlikeArray<Blk> &x) const; | |
b1f5f69e | 107 | bool operator !=(const NumberlikeArray<Blk> &x) const { return !operator ==(x); } |
5ff40cf5 | 108 | |
05780f4b MM |
109 | }; |
110 | ||
111 | /* | |
6e1e0f2f MM |
112 | * ================================= |
113 | * BELOW THIS POINT are template definitions; above are declarations. | |
114 | * | |
115 | * Definitions would ordinarily belong in a file NumberlikeArray.cc so that they would | |
116 | * be compiled once into NumberlikeArray.o and then linked. | |
117 | * | |
118 | * However, because of the way templates are usually implemented, | |
119 | * template ``definitions'' are treated as declarations by the compiler. | |
120 | * When someone uses an instance of the template, definitions are generated, | |
121 | * and the linker is smart enough to toss duplicate definitions for the same | |
122 | * instance generated by different files. | |
123 | * | |
124 | * Thus, the template ``definitions'' for NumberlikeArray must appear in this header file | |
125 | * so other files including NumberlikeArray will be able to generate real definitions. | |
126 | */ | |
05780f4b | 127 | |
2f145f11 | 128 | template <class Blk> |
4efbb076 | 129 | const unsigned int NumberlikeArray<Blk>::N = 8 * sizeof(Blk); |
2f145f11 | 130 | |
05780f4b MM |
131 | // MANAGEMENT |
132 | ||
133 | // This routine is called to ensure the array is at least a | |
134 | // certain size before another value is written into it. | |
135 | template <class Blk> | |
136 | void NumberlikeArray<Blk>::allocate(Index c) { | |
137 | // If the requested capacity is more than the current capacity... | |
138 | if (c > cap) { | |
139 | // Delete the old number array | |
a8b42b68 | 140 | delete [] blk; |
05780f4b MM |
141 | // Allocate the new array |
142 | cap = c; | |
a8b42b68 | 143 | blk = new Blk[cap]; |
05780f4b MM |
144 | } |
145 | } | |
146 | ||
147 | // This routine is called to ensure the array is at least a | |
148 | // certain size without losing its contents. | |
149 | template <class Blk> | |
150 | void NumberlikeArray<Blk>::allocateAndCopy(Index c) { | |
151 | // If the requested capacity is more than the current capacity... | |
152 | if (c > cap) { | |
a8b42b68 | 153 | Blk *oldBlk = blk; |
05780f4b MM |
154 | // Allocate the new number array |
155 | cap = c; | |
a8b42b68 | 156 | blk = new Blk[cap]; |
05780f4b MM |
157 | // Copy number blocks |
158 | Index i; | |
159 | for (i = 0; i < len; i++) | |
160 | blk[i] = oldBlk[i]; | |
161 | // Delete the old array | |
162 | delete [] oldBlk; | |
163 | } | |
164 | } | |
165 | ||
166 | // Copy constructor | |
167 | template <class Blk> | |
a8b42b68 | 168 | NumberlikeArray<Blk>::NumberlikeArray(const NumberlikeArray<Blk> &x) : len(x.len) { |
05780f4b MM |
169 | // Create array |
170 | cap = len; | |
a8b42b68 | 171 | blk = new Blk[cap]; |
05780f4b MM |
172 | // Copy blocks |
173 | Index i; | |
174 | for (i = 0; i < len; i++) | |
175 | blk[i] = x.blk[i]; | |
176 | } | |
177 | ||
178 | // Assignment operator | |
179 | template <class Blk> | |
180 | void NumberlikeArray<Blk>::operator=(const NumberlikeArray<Blk> &x) { | |
181 | // Calls like a = a have no effect | |
182 | if (this == &x) | |
183 | return; | |
184 | // Copy length | |
185 | len = x.len; | |
186 | // Expand array if necessary | |
187 | allocate(len); | |
188 | // Copy number blocks | |
189 | Index i; | |
190 | for (i = 0; i < len; i++) | |
191 | blk[i] = x.blk[i]; | |
192 | } | |
193 | ||
194 | // Constructor from an array of blocks | |
195 | template <class Blk> | |
a8b42b68 | 196 | NumberlikeArray<Blk>::NumberlikeArray(const Blk *b, Index l) : cap(l), len(l) { |
05780f4b | 197 | // Create array |
a8b42b68 | 198 | blk = new Blk[cap]; |
05780f4b MM |
199 | // Copy blocks |
200 | Index i; | |
201 | for (i = 0; i < len; i++) | |
202 | blk[i] = b[i]; | |
203 | } | |
204 | ||
205 | ||
206 | // EQUALITY TEST | |
207 | // This uses == to compare Blks for equality. | |
208 | // Therefore, Blks must have an == operator with the desired semantics. | |
209 | template <class Blk> | |
210 | bool NumberlikeArray<Blk>::operator ==(const NumberlikeArray<Blk> &x) const { | |
211 | // Different lengths imply different objects. | |
212 | if (len != x.len) | |
213 | return false; | |
214 | else { | |
215 | // Compare matching blocks one by one. | |
216 | Index i; | |
217 | for (i = 0; i < len; i++) | |
218 | if (blk[i] != x.blk[i]) | |
219 | return false; | |
220 | // If no blocks differed, the objects are equal. | |
221 | return true; | |
222 | } | |
223 | } | |
224 | ||
225 | #endif |