138 lines
3.2 KiB
D
138 lines
3.2 KiB
D
module ecs.string_intern;
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import ecs.hash_map;
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import ecs.traits : isForeachDelegateWithI;
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import std.experimental.allocator;
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import std.experimental.allocator.mallocator;
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import std.traits : Parameters;
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private __gshared static HashMap!(const(char)[], StringIntern) gStringInterns;
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struct StringIntern {
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private const(char)* strPtr;
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this(const(char)[] fromStr) {
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opAssign(fromStr);
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}
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void reset() {
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strPtr=null;
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}
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size_t length() {
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if (strPtr is null) {
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return 0;
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}
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return *cast(size_t*)(strPtr - 8);
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}
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const(char)[] str() {
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if (strPtr is null) {
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return null;
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}
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return strPtr[0 .. length];
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}
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const(char)[] cstr() {
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if (strPtr is null) {
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return "\0";
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}
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return strPtr[0 .. length + 1];
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}
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bool opEquals()(auto ref const StringIntern s) {
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return strPtr == s.strPtr;
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}
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bool opEquals()(auto ref const(char[]) s) {
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return str() == s;
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}
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void opAssign(const(char)[] fromStr) {
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if (fromStr.length == 0) {
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return;
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}
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StringIntern defaultValue;
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StringIntern internedStr = gStringInterns.get(fromStr, defaultValue);
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if (internedStr.length == 0) {
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internedStr.strPtr = allocStr(fromStr).ptr;
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gStringInterns.add(internedStr.str, internedStr);
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}
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strPtr = internedStr.strPtr;
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}
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const(char)[] opSlice() {
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if (strPtr is null) {
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return null;
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}
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return strPtr[0 .. length];
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}
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private const(char)[] allocStr(const(char)[] fromStr) {
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char[] data = Mallocator.instance.makeArray!(char)(fromStr.length + size_t.sizeof + 1);
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size_t* len = cast(size_t*) data.ptr;
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*len = fromStr.length;
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data[size_t.sizeof .. $ - 1] = fromStr;
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data[$ - 1] = '\0';
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return data[size_t.sizeof .. $ - 1];
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}
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}
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unittest {
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static assert(StringIntern.sizeof == size_t.sizeof);
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const(char)[] chA = ['a', 'a'];
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char[] chB = ['o', 't', 'h', 'e', 'r'];
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const(char)[] chC = ['o', 't', 'h', 'e', 'r'];
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string chD = "other";
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StringIntern strA;
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StringIntern strB = StringIntern("");
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StringIntern strC = StringIntern("a");
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StringIntern strD = "a";
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StringIntern strE = "aa";
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StringIntern strF = chA;
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StringIntern strG = chB;
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assert(strA == strB);
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assert(strA != strC);
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assert(strC == strD);
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assert(strD != strE);
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assert(strE == strF);
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assert(strD.length == 1);
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assert(strE.length == 2);
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assert(strG.length == 5);
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strA = "other";
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assert(strA == "other");
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assert(strA == chB);
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assert(strA == chC);
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assert(strA == chD);
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assert(strA.str.ptr[strA.str.length] == '\0');
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assert(strA.cstr[$ - 1] == '\0');
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foreach (char c; strA) {
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}
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foreach (int i, char c; strA) {
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}
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foreach (ubyte i, char c; strA) {
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}
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foreach (c; strA) {
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}
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}
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unittest {
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import ecs.hash_map : HashMap;
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HashMap!(StringIntern, StringIntern) map;
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map.add(StringIntern("aaa"), StringIntern("bbb"));
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map.add(StringIntern("aaa"), StringIntern("bbb"));
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assert(map.length == 1);
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assert(map.get(StringIntern("aaa")) == StringIntern("bbb"));
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}
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