world/book/node_modules/honkit/lib/models/hash.js

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.hash = void 0;
exports.hashString = hashString;
// v8 has an optimization for storing 31-bit signed numbers.
// Values which have either 00 or 11 as the high order bits qualify.
// This function drops the highest order bit in a signed number, maintaining
// the sign bit.
function smi(i32) {
    return ((i32 >>> 1) & 0x40000000) | (i32 & 0xbfffffff);
}
const defaultValueOf = Object.prototype.valueOf;
// If possible, use a WeakMap.
const usingWeakMap = typeof WeakMap === "function";
let weakMap;
if (usingWeakMap) {
    weakMap = new WeakMap();
}
let objHashUID = 0;
let UID_HASH_KEY = "__immutablehash__";
if (typeof Symbol === "function") {
    // @ts-expect-error ts-migrate(2322) FIXME: Type 'symbol' is not assignable to type 'string'.
    UID_HASH_KEY = Symbol(UID_HASH_KEY);
}
const STRING_HASH_CACHE_MIN_STRLEN = 16;
const STRING_HASH_CACHE_MAX_SIZE = 255;
let STRING_HASH_CACHE_SIZE = 0;
let stringHashCache = {};
const hash = function hash(o) {
    switch (typeof o) {
        case "boolean":
            // The hash values for built-in constants are a 1 value for each 5-byte
            // shift region expect for the first, which encodes the value. This
            // reduces the odds of a hash collision for these common values.
            return o ? 0x42108421 : 0x42108420;
        case "number":
            return hashNumber(o);
        case "string":
            return o.length > STRING_HASH_CACHE_MIN_STRLEN ? cachedHashString(o) : hashString(o);
        case "object":
        case "function":
            if (o === null) {
                return 0x42108422;
            }
            if (typeof o.hashCode === "function") {
                // Drop any high bits from accidentally long hash codes.
                return smi(o.hashCode(o));
            }
            if (o.valueOf !== defaultValueOf && typeof o.valueOf === "function") {
                o = o.valueOf(o);
            }
            return hashJSObj(o);
        case "undefined":
            return 0x42108423;
        default:
            if (typeof o.toString === "function") {
                return hashString(o.toString());
            }
            throw new Error(`Value type ${typeof o} cannot be hashed.`);
    }
};
exports.hash = hash;
// Compress arbitrarily large numbers into smi hashes.
function hashNumber(n) {
    if (n !== n || n === Infinity) {
        return 0;
    }
    let hash = n | 0;
    if (hash !== n) {
        hash ^= n * 0xffffffff;
    }
    while (n > 0xffffffff) {
        n /= 0xffffffff;
        hash ^= n;
    }
    return smi(hash);
}
function cachedHashString(string) {
    let hashed = stringHashCache[string];
    if (hashed === undefined) {
        hashed = hashString(string);
        if (STRING_HASH_CACHE_SIZE === STRING_HASH_CACHE_MAX_SIZE) {
            STRING_HASH_CACHE_SIZE = 0;
            stringHashCache = {};
        }
        STRING_HASH_CACHE_SIZE++;
        stringHashCache[string] = hashed;
    }
    return hashed;
}
// http://jsperf.com/hashing-strings
function hashString(string) {
    // This is the hash from JVM
    // The hash code for a string is computed as
    // s[0] * 31 ^ (n - 1) + s[1] * 31 ^ (n - 2) + ... + s[n - 1],
    // where s[i] is the ith character of the string and n is the length of
    // the string. We "mod" the result to make it between 0 (inclusive) and 2^31
    // (exclusive) by dropping high bits.
    let hashed = 0;
    for (let ii = 0; ii < string.length; ii++) {
        hashed = (31 * hashed + string.charCodeAt(ii)) | 0;
    }
    return smi(hashed);
}
function hashJSObj(obj) {
    let hashed;
    if (usingWeakMap) {
        hashed = weakMap.get(obj);
        if (hashed !== undefined) {
            return hashed;
        }
    }
    hashed = obj[UID_HASH_KEY];
    if (hashed !== undefined) {
        return hashed;
    }
    if (!canDefineProperty) {
        hashed = obj.propertyIsEnumerable && obj.propertyIsEnumerable[UID_HASH_KEY];
        if (hashed !== undefined) {
            return hashed;
        }
        hashed = getIENodeHash(obj);
        if (hashed !== undefined) {
            return hashed;
        }
    }
    hashed = ++objHashUID;
    if (objHashUID & 0x40000000) {
        objHashUID = 0;
    }
    if (usingWeakMap) {
        weakMap.set(obj, hashed);
    }
    else if (isExtensible !== undefined && isExtensible(obj) === false) {
        throw new Error("Non-extensible objects are not allowed as keys.");
    }
    else if (canDefineProperty) {
        Object.defineProperty(obj, UID_HASH_KEY, {
            enumerable: false,
            configurable: false,
            writable: false,
            value: hashed
        });
    }
    else if (obj.propertyIsEnumerable !== undefined &&
        obj.propertyIsEnumerable === obj.constructor.prototype.propertyIsEnumerable) {
        // Since we can't define a non-enumerable property on the object
        // we'll hijack one of the less-used non-enumerable properties to
        // save our hash on it. Since this is a function it will not show up in
        // `JSON.stringify` which is what we want.
        obj.propertyIsEnumerable = function () {
            return this.constructor.prototype.propertyIsEnumerable.apply(this, arguments);
        };
        obj.propertyIsEnumerable[UID_HASH_KEY] = hashed;
    }
    else if (obj.nodeType !== undefined) {
        // At this point we couldn't get the IE `uniqueID` to use as a hash
        // and we couldn't use a non-enumerable property to exploit the
        // dontEnum bug so we simply add the `UID_HASH_KEY` on the node
        // itself.
        obj[UID_HASH_KEY] = hashed;
    }
    else {
        throw new Error("Unable to set a non-enumerable property on object.");
    }
    return hashed;
}
// Get references to ES5 object methods.
const isExtensible = Object.isExtensible;
// True if Object.defineProperty works as expected. IE8 fails this test.
const canDefineProperty = (function () {
    try {
        Object.defineProperty({}, "@", {});
        return true;
    }
    catch (e) {
        return false;
    }
})();
// IE has a `uniqueID` property on DOM nodes. We can construct the hash from it
// and avoid memory leaks from the IE cloneNode bug.
function getIENodeHash(node) {
    if (node && node.nodeType > 0) {
        switch (node.nodeType) {
            case 1: // Element
                return node.uniqueID;
            case 9: // Document
                return node.documentElement && node.documentElement.uniqueID;
        }
    }
}