From 441d9c8cc0795ef9f27648e54aa5f612599048af Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sun, 25 Oct 2020 12:27:07 +0100
Subject: [PATCH] Change `src/core/{glyphlist, unicode}.js` to use standard
 `import`/`export` statements

While the *built* `pdf.worker.js` file still works correctly with these changes, despite these two files being excluded by Babel[1], the development viewer does not because of issues with SystemJS[2] and/or its Babel-plugin (both of which are old).
Furthermore, note also that excluding these two files from Babel-processing isn't *generally* necessary since e.g. the `gulp mozcentral` command works anyway. The explanation is rather that it's actually the source-map generation which fails for these huge sequences when building the `pdf.worker.js` file.

However, not using standard `import`/`export` statements in all files means we also need to use SystemJS when e.e. running the unit-tests. This is very unfortunate, since SystemJS (or its old Babel-version) doesn't support modern ECMAScript features such as e.g. optional chaining and nullish coalescing.

Unfortunately it also seems that https://bugzilla.mozilla.org/show_bug.cgi?id=1247687, which tracks the implementation of worker-modules in Firefox, has stalled since there hasn't been any updates for six months now.

To hopefully address all of the above, this patch is the first in a series that attempts to further reduce our reliance on SystemJS.

---
[1] The only difference being how the dependencies are handled, in the Webpack-bundled file.

[2] Parsing takes way too long and consumes too much memory, thus rendering the development viewer essentially unusable.
---
 src/core/glyphlist.js |  5 ++---
 src/core/unicode.js   | 14 ++++++++------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/core/glyphlist.js b/src/core/glyphlist.js
index 2bf4423a8..071d3ee8d 100644
--- a/src/core/glyphlist.js
+++ b/src/core/glyphlist.js
@@ -15,7 +15,7 @@
 /* no-babel-preset */
 /* eslint-disable no-var */
 
-var getLookupTableFactory = require("./core_utils.js").getLookupTableFactory;
+import { getLookupTableFactory } from "./core_utils.js";
 
 var getGlyphsUnicode = getLookupTableFactory(function (t) {
   t.A = 0x0041;
@@ -4550,5 +4550,4 @@ var getDingbatsGlyphsUnicode = getLookupTableFactory(function (t) {
   t[".notdef"] = 0x0000;
 });
 
-exports.getGlyphsUnicode = getGlyphsUnicode;
-exports.getDingbatsGlyphsUnicode = getDingbatsGlyphsUnicode;
+export { getGlyphsUnicode, getDingbatsGlyphsUnicode };
diff --git a/src/core/unicode.js b/src/core/unicode.js
index 118a713b1..043b8c097 100644
--- a/src/core/unicode.js
+++ b/src/core/unicode.js
@@ -15,7 +15,7 @@
 /* no-babel-preset */
 /* eslint-disable no-var */
 
-var getLookupTableFactory = require("./core_utils.js").getLookupTableFactory;
+import { getLookupTableFactory } from "./core_utils.js";
 
 // Some characters, e.g. copyrightserif, are mapped to the private use area
 // and might not be displayed using standard fonts. Mapping/hacking well-known
@@ -1635,8 +1635,10 @@ function reverseIfRtl(chars) {
   return s;
 }
 
-exports.mapSpecialUnicodeValues = mapSpecialUnicodeValues;
-exports.reverseIfRtl = reverseIfRtl;
-exports.getUnicodeRangeFor = getUnicodeRangeFor;
-exports.getNormalizedUnicodes = getNormalizedUnicodes;
-exports.getUnicodeForGlyph = getUnicodeForGlyph;
+export {
+  mapSpecialUnicodeValues,
+  reverseIfRtl,
+  getUnicodeRangeFor,
+  getNormalizedUnicodes,
+  getUnicodeForGlyph,
+};