summaryrefslogtreecommitdiff
path: root/src/ltable.js
blob: 87f8c6aa3f052c2754a9476893a87da91686124f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
"use strict";

const defs    = require('./defs.js');
const { lua_assert } = require('./llimits.js');
const ldebug  = require('./ldebug.js');
const lobject = require('./lobject.js');
const lstring = require('./lstring.js');
const lstate  = require('./lstate.js');
const CT      = defs.constant_types;

/* used to prevent conflicts with lightuserdata keys */
let lightuserdata_hashes = new WeakMap();
const get_lightuserdata_hash = function(v) {
    let hash = lightuserdata_hashes.get(v);
    if (!hash) {
        /* Hash should be something unique that is a valid WeakMap key
           so that it ends up in dead_weak when removed from a table */
        hash = {};
        lightuserdata_hashes.set(v, hash);
    }
    return hash;
};

const table_hash = function(L, key) {
    switch(key.type) {
        case CT.LUA_TNIL:
            return ldebug.luaG_runerror(L, defs.to_luastring("table index is nil", true));
        case CT.LUA_TNUMFLT:
            if (isNaN(key.value))
                return ldebug.luaG_runerror(L, defs.to_luastring("table index is NaN", true));
            /* fall through */
        case CT.LUA_TNUMINT: /* takes advantage of floats and integers being same in JS */
        case CT.LUA_TBOOLEAN:
        case CT.LUA_TTABLE:
        case CT.LUA_TLCL:
        case CT.LUA_TLCF:
        case CT.LUA_TCCL:
        case CT.LUA_TUSERDATA:
        case CT.LUA_TTHREAD:
            return key.value;
        case CT.LUA_TSHRSTR:
        case CT.LUA_TLNGSTR:
            return lstring.luaS_hashlongstr(key.tsvalue());
        case CT.LUA_TLIGHTUSERDATA: {
            let v = key.value;
            switch(typeof v) {
                case "string":
                    /* possible conflict with LUA_TSTRING.
                       prefix this string with "*" so they don't clash */
                    return "*" + v;
                case "number":
                    /* possible conflict with LUA_TNUMBER.
                       turn into string and prefix with "#" to avoid clash with other strings */
                    return "#" + v;
                case "boolean":
                    /* possible conflict with LUA_TBOOLEAN. use strings ?true and ?false instead */
                    return v?"?true":"?false";
                case "function":
                    /* possible conflict with LUA_TLCF.
                       indirect via a weakmap */
                    return get_lightuserdata_hash(v);
                case "object":
                    /* v could be a lua_State, CClosure, LClosure, Table or Userdata from this state as returned by lua_topointer */
                    if ((v instanceof lstate.lua_State && v.l_G === L.l_G) ||
                        v instanceof Table ||
                        v instanceof lobject.Udata ||
                        v instanceof lobject.LClosure ||
                        v instanceof lobject.CClosure) {
                        /* indirect via a weakmap */
                        return get_lightuserdata_hash(v);
                    }
                    /* fall through */
                default:
                    return v;
            }
        }
        default:
            throw new Error("unknown key type: " + key.type);
    }
};

class Table {
    constructor(L) {
        this.id = L.l_G.id_counter++;
        this.strong = new Map();
        this.dead_strong = new Map();
        this.dead_weak = void 0; /* initialised when needed */
        this.f = void 0; /* first entry */
        this.l = void 0; /* last entry */
        this.metatable = null;
        this.flags = ~0;
    }
}

const invalidateTMcache = function(t) {
    t.flags = 0;
};

const add = function(t, hash, key, value) {
    t.dead_strong.clear();
    t.dead_weak = void 0;
    let prev = null;
    let entry = {
        key: key,
        value: value,
        p: prev = t.l,
        n: void 0
    };
    if (!t.f) t.f = entry;
    if (prev) prev.n = entry;
    t.strong.set(hash, entry);
    t.l = entry;
};

const is_valid_weakmap_key = function(k) {
    return typeof k === 'object' ? k !== null : typeof k === 'function';
};

/* Move out of 'strong' part and into 'dead' part. */
const mark_dead = function(t, hash) {
    let e = t.strong.get(hash);
    if (e) {
        e.key.setdeadvalue();
        e.value = void 0;
        let next = e.n;
        let prev = e.p;
        e.p = void 0; /* no need to know previous item any more */
        if(prev) prev.n = next;
        if(next) next.p = prev;
        if(t.f === e) t.f = next;
        if(t.l === e) t.l = prev;
        t.strong.delete(hash);
        if (is_valid_weakmap_key(hash)) {
            if (!t.dead_weak) t.dead_weak = new WeakMap();
            t.dead_weak.set(hash, e);
        } else {
            /* can't be used as key in weakmap */
            t.dead_strong.set(hash, e);
        }
    }
};

const luaH_new = function(L) {
    return new Table(L);
};

const getgeneric = function(t, hash) {
    let v = t.strong.get(hash);
    return v ? v.value : lobject.luaO_nilobject;
};

const luaH_getint = function(t, key) {
    lua_assert(typeof key == "number" && (key|0) === key);
    return getgeneric(t, key);
};

const luaH_getstr = function(t, key) {
    lua_assert(key instanceof lstring.TString);
    return getgeneric(t, lstring.luaS_hashlongstr(key));
};

const luaH_get = function(L, t, key) {
    lua_assert(key instanceof lobject.TValue);
    if (key.ttisnil() || (key.ttisfloat() && isNaN(key.value)))
        return lobject.luaO_nilobject;
    return getgeneric(t, table_hash(L, key));
};

const setgeneric = function(t, hash, key) {
    let v = t.strong.get(hash);
    if (v)
        return v.value;

    let kv = key.value;
    if ((key.ttisfloat() && (kv|0) === kv)) { /* does index fit in an integer? */
        /* insert it as an integer */
        key = new lobject.TValue(CT.LUA_TNUMINT, kv);
    } else {
        key = new lobject.TValue(key.type, kv);
    }
    let tv = new lobject.TValue(CT.LUA_TNIL, null);
    add(t, hash, key, tv);
    return tv;
};

const luaH_setint = function(t, key, value) {
    lua_assert(typeof key == "number" && (key|0) === key && value instanceof lobject.TValue);
    let hash = key; /* table_hash known result */
    if (value.ttisnil()) {
        mark_dead(t, hash);
        return;
    }
    let v = t.strong.get(hash);
    if (v) {
        let tv = v.value;
        tv.setfrom(value);
    } else {
        let k = new lobject.TValue(CT.LUA_TNUMINT, key);
        let v = new lobject.TValue(value.type, value.value);
        add(t, hash, k, v);
    }
};

const luaH_set = function(L, t, key) {
    lua_assert(key instanceof lobject.TValue);
    let hash = table_hash(L, key);
    return setgeneric(t, hash, key);
};

const luaH_delete = function(L, t, key) {
    lua_assert(key instanceof lobject.TValue);
    let hash = table_hash(L, key);
    return mark_dead(t, hash);
};

/*
** Try to find a boundary in table 't'. A 'boundary' is an integer index
** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
*/
const luaH_getn = function(t) {
    let i = 0;
    let j = t.strong.size + 1; /* use known size of Map to bound search */
    /* now do a binary search between them */
    while (j - i > 1) {
        let m = Math.floor((i+j)/2);
        if (luaH_getint(t, m).ttisnil()) j = m;
        else i = m;
    }
    return i;
};

const luaH_next = function(L, table, keyI) {
    let keyO = L.stack[keyI];

    let entry;
    if (keyO.type === CT.LUA_TNIL) {
        entry = table.f;
        if (!entry)
            return false;
    } else {
        /* First find current key */
        let hash = table_hash(L, keyO);
        /* Look in main part of table */
        entry = table.strong.get(hash);
        if (entry) {
            entry = entry.n;
            if (!entry)
                return false;
        } else {
            /* Try dead keys */
            entry = (table.dead_weak && table.dead_weak.get(hash)) || table.dead_strong.get(hash);
            if (!entry)
                /* item not in table */
                return ldebug.luaG_runerror(L, defs.to_luastring("invalid key to 'next'"));
            /* Iterate until either out of keys, or until finding a non-dead key */
            do {
                entry = entry.n;
                if (!entry)
                    return false;
            } while (entry.key.ttisdeadkey());
        }
    }
    lobject.setobj2s(L, keyI, entry.key);
    lobject.setobj2s(L, keyI+1, entry.value);
    return true;
};

module.exports.invalidateTMcache = invalidateTMcache;
module.exports.luaH_delete  = luaH_delete;
module.exports.luaH_get     = luaH_get;
module.exports.luaH_getint  = luaH_getint;
module.exports.luaH_getn    = luaH_getn;
module.exports.luaH_getstr  = luaH_getstr;
module.exports.luaH_set     = luaH_set;
module.exports.luaH_setint  = luaH_setint;
module.exports.luaH_new     = luaH_new;
module.exports.luaH_next    = luaH_next;
module.exports.Table        = Table;