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const {Number:NumberT} = require('./Number');
const utils = require('./utils');
class ArrayT {
constructor(type, length, lengthType = 'count') {
this.type = type;
this.length = length;
this.lengthType = lengthType;
}
decode(stream, parent) {
let length;
const { pos } = stream;
const res = [];
let ctx = parent;
if (this.length != null) {
length = utils.resolveLength(this.length, stream, parent);
}
if (this.length instanceof NumberT) {
// define hidden properties
Object.defineProperties(res, {
parent: { value: parent },
_startOffset: { value: pos },
_currentOffset: { value: 0, writable: true },
_length: { value: length }
});
ctx = res;
}
if ((length == null) || (this.lengthType === 'bytes')) {
const target = (length != null) ?
stream.pos + length
: (parent != null ? parent._length : undefined) ?
parent._startOffset + parent._length
:
stream.length;
while (stream.pos < target) {
res.push(this.type.decode(stream, ctx));
}
} else {
for (let i = 0, end = length; i < end; i++) {
res.push(this.type.decode(stream, ctx));
}
}
return res;
}
size(array, ctx) {
if (!array) {
return this.type.size(null, ctx) * utils.resolveLength(this.length, null, ctx);
}
let size = 0;
if (this.length instanceof NumberT) {
size += this.length.size();
ctx = {parent: ctx};
}
for (let item of array) {
size += this.type.size(item, ctx);
}
return size;
}
encode(stream, array, parent) {
let ctx = parent;
if (this.length instanceof NumberT) {
ctx = {
pointers: [],
startOffset: stream.pos,
parent
};
ctx.pointerOffset = stream.pos + this.size(array, ctx);
this.length.encode(stream, array.length);
}
for (let item of array) {
this.type.encode(stream, item, ctx);
}
if (this.length instanceof NumberT) {
let i = 0;
while (i < ctx.pointers.length) {
const ptr = ctx.pointers[i++];
ptr.type.encode(stream, ptr.val);
}
}
}
}
module.exports = ArrayT;