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denoland-deno/js/flatbuffers.ts
2018-10-24 08:54:34 -07:00

54 lines
1.8 KiB
TypeScript

// Copyright 2018 the Deno authors. All rights reserved. MIT license.
import { flatbuffers } from "flatbuffers";
import * as util from "./util";
// Re-export some types.
export type Offset = flatbuffers.Offset;
export class ByteBuffer extends flatbuffers.ByteBuffer {}
export interface Builder extends flatbuffers.Builder {
inUse: boolean;
}
const globalBuilder = new flatbuffers.Builder() as Builder;
globalBuilder.inUse = false;
// This is a wrapper around the real Builder .
// The purpose is to reuse a single ArrayBuffer for every message.
// We can do this because the "control" messages sent to the privileged
// side are guaranteed to be used during the call to libdeno.send().
export function createBuilder(): Builder {
// tslint:disable-next-line:no-any
const gb = globalBuilder as any;
util.assert(!gb.inUse);
let bb = globalBuilder.dataBuffer();
// Only create a new backing ArrayBuffer if the previous one had grown very
// large in capacity. This should only happen rarely.
if (bb.capacity() > 1024) {
util.log(`realloc flatbuffer ArrayBuffer because it was ${bb.capacity()}`);
bb = ByteBuffer.allocate(1024);
}
gb.bb = bb;
// Remaining space in the ByteBuffer.
gb.space = globalBuilder.dataBuffer().capacity();
// Minimum alignment encountered so far.
gb.minalign = 1;
// The vtable for the current table.
gb.vtable = null;
// The amount of fields we're actually using.
gb.vtable_in_use = 0;
// Whether we are currently serializing a table.
gb.isNested = false;
// Starting offset of the current struct/table.
gb.object_start = 0;
// List of offsets of all vtables.
gb.vtables = [];
// For the current vector being built.
gb.vector_num_elems = 0;
// False omits default values from the serialized data
gb.force_defaults = false;
gb.inUse = true;
return gb as Builder;
}