From 8dcfaf32bdd34c01c0b3e90281d979faf6038e22 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sun, 14 Feb 2021 16:24:01 +0100
Subject: [PATCH] [api-minor] Change the `dc:subject` Metadata field to an
 Array

This patch simply extends the existing handling of the `dc:creator` field, which should hopefully suffice here; please refer to https://wwwimages2.adobe.com/content/dam/acom/en/devnet/xmp/pdfs/XMP%20SDK%20Release%20cc-2016-08/XMPSpecificationPart1.pdf#page=34
---
 src/display/metadata.js    | 36 +++++++++++++++++++++---------------
 test/unit/metadata_spec.js |  2 +-
 2 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/src/display/metadata.js b/src/display/metadata.js
index 54ff9f7c2af1fb..9c363205c9e72e 100644
--- a/src/display/metadata.js
+++ b/src/display/metadata.js
@@ -89,22 +89,24 @@ class Metadata {
     return entry.childNodes.filter(node => node.nodeName === "rdf:li");
   }
 
-  _getCreators(entry) {
-    if (entry.nodeName !== "dc:creator") {
-      return false;
-    }
+  _getArray(entry) {
+    const name = entry.nodeName;
+    assert(
+      name === "dc:creator" || name === "dc:subject",
+      `_getArray - unexpected type: "${name}".`
+    );
+
     if (!entry.hasChildNodes()) {
       return true;
     }
-
     // Child must be a Bag (unordered array) or a Seq.
-    const seqNode = entry.childNodes[0];
-    const authors = this._getSequence(seqNode) || [];
+    const [seqNode] = entry.childNodes;
+    const sequence = this._getSequence(seqNode) || [];
+
     this._metadataMap.set(
-      entry.nodeName,
-      authors.map(node => node.textContent.trim())
+      name,
+      sequence.map(node => node.textContent.trim())
     );
-
     return true;
   }
 
@@ -130,11 +132,15 @@ class Metadata {
 
       for (const entry of desc.childNodes) {
         const name = entry.nodeName;
-        if (name === "#text") {
-          continue;
-        }
-        if (this._getCreators(entry)) {
-          continue;
+        switch (name) {
+          case "#text":
+            continue;
+          case "dc:creator":
+          case "dc:subject":
+            if (this._getArray(entry)) {
+              continue;
+            }
+            break;
         }
         this._metadataMap.set(name, entry.textContent.trim());
       }
diff --git a/test/unit/metadata_spec.js b/test/unit/metadata_spec.js
index 7d6b0d3246bdd1..557e957bbb6aad 100644
--- a/test/unit/metadata_spec.js
+++ b/test/unit/metadata_spec.js
@@ -171,7 +171,7 @@ describe("metadata", function () {
       "dc:creator": [""],
       "dc:description": "",
       "dc:format": "application/pdf",
-      "dc:subject": "",
+      "dc:subject": [],
       "dc:title": "",
       "pdf:keywords": "",
       "pdf:pdfversion": "1.7",