From 0bb3ce69353d94f88da4658768fbac2934a035f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Harrtell?=
 <bjornharrtell@users.noreply.github.com>
Date: Thu, 16 May 2019 20:43:31 +0200
Subject: [JS/TS] Size prefix support (#5326)

* WIP size prefix support

* Consider size prefix in overloaded variant

* Work on code gen

* Disabled helper functions in code gen

* Enabled helper functions in code gen

* Fix size prefixed test

* Fix bad function call

* Add SIZE_PREFIX_LENGTH

* Fix review comments
---
 js/flatbuffers.js | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

(limited to 'js')

diff --git a/js/flatbuffers.js b/js/flatbuffers.js
index 41608520..461cd7af 100644
--- a/js/flatbuffers.js
+++ b/js/flatbuffers.js
@@ -48,6 +48,12 @@ flatbuffers.SIZEOF_INT = 4;
  */
 flatbuffers.FILE_IDENTIFIER_LENGTH = 4;
 
+/**
+ * @type {number}
+ * @const
+ */
+flatbuffers.SIZE_PREFIX_LENGTH = 4;
+
 /**
  * @enum {number}
  */
@@ -676,12 +682,14 @@ outer_loop:
  *
  * @param {flatbuffers.Offset} root_table
  * @param {string=} opt_file_identifier
+ * @param {boolean=} opt_size_prefix
  */
-flatbuffers.Builder.prototype.finish = function(root_table, opt_file_identifier) {
+flatbuffers.Builder.prototype.finish = function(root_table, opt_file_identifier, opt_size_prefix) {
+  var size_prefix = opt_size_prefix ? flatbuffers.SIZE_PREFIX_LENGTH : 0;
   if (opt_file_identifier) {
     var file_identifier = opt_file_identifier;
     this.prep(this.minalign, flatbuffers.SIZEOF_INT +
-      flatbuffers.FILE_IDENTIFIER_LENGTH);
+      flatbuffers.FILE_IDENTIFIER_LENGTH + size_prefix);
     if (file_identifier.length != flatbuffers.FILE_IDENTIFIER_LENGTH) {
       throw new Error('FlatBuffers: file identifier must be length ' +
         flatbuffers.FILE_IDENTIFIER_LENGTH);
@@ -690,11 +698,24 @@ flatbuffers.Builder.prototype.finish = function(root_table, opt_file_identifier)
       this.writeInt8(file_identifier.charCodeAt(i));
     }
   }
-  this.prep(this.minalign, flatbuffers.SIZEOF_INT);
+  this.prep(this.minalign, flatbuffers.SIZEOF_INT + size_prefix);
   this.addOffset(root_table);
+  if (size_prefix) {
+    this.addInt32(this.bb.capacity() - this.space);
+  }
   this.bb.setPosition(this.space);
 };
 
+/**
+ * Finalize a size prefixed buffer, pointing to the given `root_table`.
+ *
+ * @param {flatbuffers.Offset} root_table
+ * @param {string=} opt_file_identifier
+ */
+flatbuffers.Builder.prototype.finishSizePrefixed = function (root_table, opt_file_identifier) {
+  this.finish(root_table, opt_file_identifier, true);
+};
+
 /// @cond FLATBUFFERS_INTERNAL
 /**
  * This checks a required field has been set in a given table that has
-- 
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