From 2b8208b1e2fa461cbd598791ee85d912b92b894d Mon Sep 17 00:00:00 2001
From: Eric Anderson <eanders@microsoft.com>
Date: Tue, 14 Jul 2020 16:32:12 -0700
Subject: [PATCH] Perf: Move multiline xml text encoding out of domToText
 (#4046)

* Move multiline xml text encoding out of domToText
---
 core/field_multilineinput.js | 27 +++++++++++++++++++++++++++
 core/xml.js                  | 11 -----------
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/core/field_multilineinput.js b/core/field_multilineinput.js
index 4b5ccd741..d87c3e3ad 100644
--- a/core/field_multilineinput.js
+++ b/core/field_multilineinput.js
@@ -69,6 +69,33 @@ Blockly.FieldMultilineInput.fromJson = function(options) {
   return new Blockly.FieldMultilineInput(text, undefined, options);
 };
 
+/**
+ * Serializes this field's value to XML. Should only be called by Blockly.Xml.
+ * @param {!Element} fieldElement The element to populate with info about the
+ *    field's state.
+ * @return {!Element} The element containing info about the field's state.
+ * @package
+ */
+Blockly.FieldMultilineInput.prototype.toXml = function(fieldElement) {
+  // Replace '\n' characters with html-escaped equivalent '&#10'. This is
+  // needed so the plain-text representation of the xml produced by
+  // `Blockly.Xml.domToText` will appear on a single line (this is a limitation
+  // of the plain-text format).
+  fieldElement.textContent = this.getValue().replace(/\n/g, '&#10;');
+  return fieldElement;
+};
+
+/**
+ * Sets the field's value based on the given XML element. Should only be
+ * called by Blockly.Xml.
+ * @param {!Element} fieldElement The element containing info about the
+ *    field's state.
+ * @package
+ */
+Blockly.FieldMultilineInput.prototype.fromXml = function(fieldElement) {
+  this.setValue(fieldElement.textContent.replace(/&#10;/g, '\n'));
+};
+
 /**
  * Create the block UI for this field.
  * @package
diff --git a/core/xml.js b/core/xml.js
index 45b3e0ca6..81f49fa1b 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -311,17 +311,6 @@ Blockly.Xml.cloneShadow_ = function(shadow, opt_noId) {
  */
 Blockly.Xml.domToText = function(dom) {
   var text = Blockly.utils.xml.domToText(dom);
-  // Replace line breaks in text content with '&#10;' to make them single line.
-  // E.g. <foo>hello\nworld</foo> -> <foo>hello&#10;world</foo>
-  // Do not replace line breaks between tags.
-  // E.g. ...</foo>\n</bar> is unchanged.
-  // Can't use global flag on regexp since backtracking is needed.
-  var regexp = /(<[^/](?:[^>]*[^/])?>[^<]*)\n([^<]*<\/)/;
-  var oldText;
-  do {
-    oldText = text;
-    text = text.replace(regexp, '$1&#10;$2');
-  } while (text != oldText);
   // Unpack self-closing tags.  These tags fail when embedded in HTML.
   // <block name="foo"/> -> <block name="foo"></block>
   return text.replace(/<(\w+)([^<]*)\/>/g, '<$1$2></$1>');