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index.js
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index.js
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const globalVar = new Function('return this')(); // eslint-disable-line no-new-func
const HAS_BUFFER = typeof globalVar.Buffer === 'function';
const HAS_BLOB = typeof globalVar.Blob === 'function';
const HAS_ARRAY_BUFFER = typeof globalVar.ArrayBuffer === 'function';
const HAS_DATA_VIEW = typeof globalVar.DataView === 'function';
const HAS_TYPED_ARRAY = typeof globalVar.Int8Array === 'function';
// Overhead of an list item or map key-value pair (undocumented)
const NESTED_ITEM_OVERHEAD = 1;
// Overhead of a map or list object
const COMPOSITE_ITEM_OVERHEAD = 3;
const TypedArrayTypes = [
'Int8Array',
'Uint8Array',
'Uint8ClampedArray',
'Int16Array',
'Uint16Array',
'Int32Array',
'Uint32Array',
'Float32Array',
'Float64Array',
'BigInt64Array',
'BigUint64Array',
];
const isObject = x => typeof x === 'object' && x !== null && !Array.isArray(x) && x.wrapperName !== 'Set';
const isArray = x => Array.isArray(x);
const isNumber = x => typeof x === 'number';
const isString = x => typeof x === 'string';
const isBoolean = x => typeof x === 'boolean';
const isNull = x => x === null;
const isSet = x => typeof x === 'object' && x !== null && x.wrapperName === 'Set';
const isBinary = x => {
if (typeof x === 'object' && x !== null) {
if (HAS_BUFFER && Buffer.isBuffer(x)) return true;
if (HAS_BLOB && x.constructor.name === 'Blob') return true;
if (HAS_ARRAY_BUFFER && x.constructor.name === 'ArrayBuffer') return true;
if (HAS_DATA_VIEW && x.constructor.name === 'DataView') return true;
if (HAS_TYPED_ARRAY && TypedArrayTypes.includes(x.constructor.name)) return true;
}
return false;
};
const calculateObject = x => {
let size = COMPOSITE_ITEM_OVERHEAD;
const keys = Object.getOwnPropertyNames(x);
for (const key of keys) {
const val = x[key];
const keySize = calculateString(key);
const valSize = calculateUnknown(val);
size += keySize + valSize + NESTED_ITEM_OVERHEAD;
}
return size;
};
const calculateArray = x => {
let size = COMPOSITE_ITEM_OVERHEAD;
size += x.reduce((size, nextItem) => size + calculateUnknown(nextItem) + NESTED_ITEM_OVERHEAD, 0);
return size;
};
const calculateString = x => {
if (HAS_BUFFER) {
return Buffer.byteLength(x, 'utf8');
} else {
return new Blob([x]).size;
}
};
const calculateBoolean = () => 1;
const log10 = Math.log(10);
const calculateSignificantDigits = x => {
let n = Math.abs(String(x).replace('.', ''));
if (n === 0) return 0;
while (n !== 0 && n % 10 === 0) {
n /= 10;
}
return Math.floor(Math.log(n) / log10) + 1;
};
const calculateNumber = x => {
if (!Number.isNaN(x) || !Number.isFinite(x)) {
return 0; // FIXME: How much do these take up?
}
return Math.ceil(calculateSignificantDigits(x) / 2) + (x >= 0 ? 1 : 2);
};
const calculateNull = () => 1;
const calculateSet = x => {
let calculator;
switch (x.type) {
case 'String':
calculator = calculateString;
break;
case 'Number':
case 'NumberValue':
calculator = calculateNumber;
break;
case 'Binary':
calculator = calculateBinary;
break;
default: throw new Error('unknown set type ' + x.type);
}
return x.values.reduce((total, nextItem) => total + calculator(nextItem), 0);
};
const calculateBinary = x => {
if (HAS_BUFFER && Buffer.isBuffer(x)) return x.length;
if (HAS_BLOB && (x.constructor.name === 'Blob' || x.constructor.name === 'File')) return x.size;
if (HAS_ARRAY_BUFFER && x.constructor.name === 'ArrayBuffer') return x.byteLength;
if (HAS_DATA_VIEW && x.constructor.name === 'DataView') return x.byteLength;
if (HAS_TYPED_ARRAY && TypedArrayTypes.includes(x.constructor.name)) return x.byteLength;
return 0;
};
const calculateUnknown = x => {
if (isArray(x)) {
return calculateArray(x);
} else if (isSet(x)) {
return calculateSet(x);
} else if (isObject(x)) {
return calculateObject(x);
} else if (isString(x)) {
return calculateString(x);
} else if (isNumber(x)) {
return calculateNumber(x);
} else if (isBoolean(x)) {
return calculateBoolean(x);
} else if (isBinary(x)) {
return calculateBinary(x);
} else if (isNull(x)) {
return calculateNull(x);
}
return 0;
};
module.exports = function calculateDocumentSize (doc) {
if (!isObject(doc)) {
throw new Error('Expected an object for document');
}
let size = 0;
const keys = Object.getOwnPropertyNames(doc);
for (const key of keys) {
const val = doc[key];
const keySize = calculateString(key);
const valSize = calculateUnknown(val);
size += keySize + valSize;
}
return size;
};
Object.assign(module.exports, {
calculateString,
calculateUnknown,
calculateSet,
calculateNull,
calculateBinary,
calculateNumber,
calculateBoolean,
calculateObject,
calculateArray,
});