From 2d88ccec2a03f990626a06a4be10c65255436d7e Mon Sep 17 00:00:00 2001
From: Andrew Porritt <aporritt@gogo-robot.com>
Date: Mon, 7 Oct 2019 16:00:52 +0100
Subject: [PATCH 1/2] Add mapDocInPlace to modify the doc without creating
 unnecessary copies

---
 src/doc/doc-utils.js     | 16 ++++++++++++++++
 src/language-js/embed.js | 11 ++++++-----
 src/main/core.js         |  4 ++--
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/src/doc/doc-utils.js b/src/doc/doc-utils.js
index 656617a13a42..f27f4d762e5c 100644
--- a/src/doc/doc-utils.js
+++ b/src/doc/doc-utils.js
@@ -72,6 +72,21 @@ function mapDoc(doc, cb) {
   return cb(doc);
 }
 
+function mapDocInPlace(doc, cb) {
+  if (doc.type === "concat" || doc.type === "fill") {
+    for (let partIndex = 0; partIndex < doc.parts.length; ++partIndex) {
+      doc.parts[partIndex] = mapDocInPlace(doc.parts[partIndex], cb);
+    }
+  } else if (doc.type === "if-break") {
+    doc.breakContents =
+      doc.breakContents && mapDocInPlace(doc.breakContents, cb);
+    doc.flatContents = doc.flatContents && mapDocInPlace(doc.flatContents, cb);
+  } else if (doc.contents) {
+    doc.contents = mapDocInPlace(doc.contents, cb);
+  }
+  return cb(doc);
+}
+
 function findInDoc(doc, fn, defaultValue) {
   let result = defaultValue;
   let hasStopped = false;
@@ -212,6 +227,7 @@ module.exports = {
   traverseDoc,
   findInDoc,
   mapDoc,
+  mapDocInPlace,
   propagateBreaks,
   removeLines,
   stripTrailingHardline
diff --git a/src/language-js/embed.js b/src/language-js/embed.js
index eb3e1e9d3666..76c7318eb53a 100644
--- a/src/language-js/embed.js
+++ b/src/language-js/embed.js
@@ -13,7 +13,7 @@ const {
     group,
     dedentToRoot
   },
-  utils: { mapDoc, stripTrailingHardline }
+  utils: { mapDoc, mapDocInPlace, stripTrailingHardline }
 } = require("../doc");
 
 function embed(path, print, textToDoc, options) {
@@ -110,7 +110,7 @@ function embed(path, print, textToDoc, options) {
           }
 
           if (doc) {
-            doc = escapeTemplateCharacters(doc, false);
+            doc = escapeTemplateCharacters(doc, false, true);
             if (!isFirst && startsWithBlankLine) {
               parts.push("");
             }
@@ -194,7 +194,7 @@ function embed(path, print, textToDoc, options) {
 
   function printMarkdown(text) {
     const doc = textToDoc(text, { parser: "markdown", __inJsTemplate: true });
-    return stripTrailingHardline(escapeTemplateCharacters(doc, true));
+    return stripTrailingHardline(escapeTemplateCharacters(doc, true, true));
   }
 }
 
@@ -207,8 +207,9 @@ function uncook(cookedValue) {
   return cookedValue.replace(/([\\`]|\$\{)/g, "\\$1");
 }
 
-function escapeTemplateCharacters(doc, raw) {
-  return mapDoc(doc, currentDoc => {
+function escapeTemplateCharacters(doc, raw, mapInPlace) {
+  const mapFunc = mapInPlace ? mapDocInPlace : mapDocInPlace;
+  return mapFunc(doc, currentDoc => {
     if (!currentDoc.parts) {
       return currentDoc;
     }
diff --git a/src/main/core.js b/src/main/core.js
index 0f37afe6ae2b..4331dd43128d 100644
--- a/src/main/core.js
+++ b/src/main/core.js
@@ -14,7 +14,7 @@ const {
 const rangeUtil = require("./range-util");
 const privateUtil = require("../common/util");
 const {
-  utils: { mapDoc },
+  utils: { mapDocInPlace },
   printer: { printDocToString },
   debug: { printDocToDebug }
 } = require("../doc");
@@ -89,7 +89,7 @@ function coreFormat(text, opts, addAlignmentSize) {
   const result = printDocToString(
     opts.endOfLine === "lf"
       ? doc
-      : mapDoc(doc, currentDoc =>
+      : mapDocInPlace(doc, currentDoc =>
           typeof currentDoc === "string" && currentDoc.indexOf("\n") !== -1
             ? currentDoc.replace(/\n/g, eol)
             : currentDoc

From cb8b831a216e146d0d28c96b5a24d34f17a789b0 Mon Sep 17 00:00:00 2001
From: Andrew Porritt <aporritt@gogo-robot.com>
Date: Mon, 7 Oct 2019 17:13:01 +0100
Subject: [PATCH 2/2] Remove extra parameter for escapeTemplateCharacters in
 favour of a comment

---
 src/language-js/embed.js | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/language-js/embed.js b/src/language-js/embed.js
index 76c7318eb53a..b122613de3bf 100644
--- a/src/language-js/embed.js
+++ b/src/language-js/embed.js
@@ -110,7 +110,7 @@ function embed(path, print, textToDoc, options) {
           }
 
           if (doc) {
-            doc = escapeTemplateCharacters(doc, false, true);
+            doc = escapeTemplateCharacters(doc, false);
             if (!isFirst && startsWithBlankLine) {
               parts.push("");
             }
@@ -194,7 +194,7 @@ function embed(path, print, textToDoc, options) {
 
   function printMarkdown(text) {
     const doc = textToDoc(text, { parser: "markdown", __inJsTemplate: true });
-    return stripTrailingHardline(escapeTemplateCharacters(doc, true, true));
+    return stripTrailingHardline(escapeTemplateCharacters(doc, true));
   }
 }
 
@@ -207,9 +207,10 @@ function uncook(cookedValue) {
   return cookedValue.replace(/([\\`]|\$\{)/g, "\\$1");
 }
 
-function escapeTemplateCharacters(doc, raw, mapInPlace) {
-  const mapFunc = mapInPlace ? mapDocInPlace : mapDocInPlace;
-  return mapFunc(doc, currentDoc => {
+// Note that this uses mapDocInPlace, and so modifies the
+// original doc object.
+function escapeTemplateCharacters(doc, raw) {
+  return mapDocInPlace(doc, currentDoc => {
     if (!currentDoc.parts) {
       return currentDoc;
     }