1 /** 2 * Compiler implementation of the 3 * $(LINK2 http://www.dlang.org, D programming language). 4 * 5 * Copyright: Copyright (C) 2018-2020 by The D Language Foundation, All Rights Reserved 6 * Authors: $(LINK2 http://www.digitalmars.com, Walter Bright) 7 * License: $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0) 8 * Source: $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/backend/barrayf.d, backend/barray.d) 9 * Documentation: https://dlang.org/phobos/dmd_backend_barray.html 10 */ 11 12 module dmd.backend.barray; 13 14 import core.stdc.stdio; 15 import core.stdc.stdlib; 16 import core.stdc..string; 17 18 nothrow: 19 20 extern (C++): void err_nomem(); 21 22 /************************************* 23 * A reusable array that ratchets up in capacity. 24 */ 25 struct Barray(T) 26 { 27 /********************** 28 * Set useable length of array. 29 * Params: 30 * length = minimum number of elements in array 31 */ 32 void setLength(size_t length) 33 { 34 static void enlarge(ref Barray barray, size_t length) 35 { 36 pragma(inline, false); 37 auto newcap = (barray.capacity == 0) ? length : length + (length >> 1); 38 barray.capacity = (newcap + 15) & ~15; 39 T* p = cast(T*)realloc(barray.array.ptr, barray.capacity * T.sizeof); 40 if (length && !p) 41 { 42 version (unittest) 43 assert(0); 44 else 45 err_nomem(); 46 } 47 barray.array = p[0 .. length]; 48 } 49 50 if (length <= capacity) 51 array = array.ptr[0 .. length]; // the fast path 52 else 53 enlarge(this, length); // the slow path 54 } 55 56 57 /******************* 58 * Append element t to array. 59 * Params: 60 * t = element to append 61 */ 62 void push(T t) 63 { 64 const i = length; 65 setLength(i + 1); 66 array[i] = t; 67 } 68 69 /********************** 70 * Move the last element from the array into [i]. 71 * Reduce the array length by one. 72 * Params: 73 * i = index of element to remove 74 */ 75 void remove(size_t i) 76 { 77 const len = length - 1; 78 if (i != len) 79 { 80 array[i] = array[len]; 81 } 82 setLength(len); 83 } 84 85 /****************** 86 * Release all memory used. 87 */ 88 ~this() 89 { 90 free(array.ptr); 91 array = null; 92 capacity = 0; 93 } 94 95 alias array this; 96 T[] array; 97 98 private: 99 size_t capacity; 100 } 101 102 unittest 103 { 104 Barray!int a; 105 a.setLength(10); 106 assert(a.length == 10); 107 a.setLength(4); 108 assert(a.length == 4); 109 foreach (i, ref v; a[]) 110 v = cast(int) i * 2; 111 foreach (i, ref const v; a[]) 112 assert(v == i * 2); 113 a.remove(3); 114 assert(a.length == 3); 115 a.push(50); 116 a.remove(1); 117 assert(a[1] == 50); 118 }