From 2ccacf03f56137821aa45bd93a42c1a302522993 Mon Sep 17 00:00:00 2001
From: David Anson <david@dlaa.me>
Date: Mon, 4 Mar 2019 19:54:23 -0800
Subject: [PATCH] MD037 should try to ignore escaped emphasis markers (fixes
 #168).

---
 lib/md037.js                     | 17 ++++++++++-------
 test/escaped-emphasis-markers.md | 29 +++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 7 deletions(-)
 create mode 100644 test/escaped-emphasis-markers.md

diff --git a/lib/md037.js b/lib/md037.js
index ebf80868..44582381 100644
--- a/lib/md037.js
+++ b/lib/md037.js
@@ -11,18 +11,21 @@ module.exports = {
   "function": function MD037(params, onError) {
     shared.forEachInlineChild(params, "text", function forToken(token) {
       let left = true;
-      let match = /(?:^|\s)(\*\*?|__?)\s.+\1/.exec(token.content);
+      let match = /(?:^|\s)(\*\*?|__?)\s.*[^\\]\1/.exec(token.content);
       if (!match) {
         left = false;
-        match = /(\*\*?|__?).+\s\1(?:\s|$)/.exec(token.content);
+        match = /(?:^|[^\\])(\*\*?|__?).+\s\1(?:\s|$)/.exec(token.content);
       }
       if (match) {
-        const text = match[0].trim();
+        const fullText = match[0];
         const line = params.lines[token.lineNumber - 1];
-        const column = line.indexOf(text) + 1;
-        const length = text.length;
-        shared.addErrorContext(onError, token.lineNumber,
-          text, left, !left, [ column, length ]);
+        if (line.indexOf(fullText) !== -1) {
+          const text = fullText.trim();
+          const column = line.indexOf(text) + 1;
+          const length = text.length;
+          shared.addErrorContext(onError, token.lineNumber,
+            text, left, !left, [ column, length ]);
+        }
       }
     });
   }
diff --git a/test/escaped-emphasis-markers.md b/test/escaped-emphasis-markers.md
new file mode 100644
index 00000000..319dc294
--- /dev/null
+++ b/test/escaped-emphasis-markers.md
@@ -0,0 +1,29 @@
+# Heading
+
+Escaped asterisks \* should \* be ignored by MD037.
+
+Escaped asterisks \* should * be ignored by MD037.
+
+Escaped asterisks * should \* be ignored by MD037.
+
+Escaped asterisks \** should ** be ignored by MD037.
+
+Escaped asterisks *\* should ** be ignored by MD037.
+
+Escaped asterisks ** should \** be ignored by MD037.
+
+Escaped asterisks ** should *\* be ignored by MD037.
+
+Escaped underscores \_ should \_ be ignored by MD037.
+
+Escaped underscores \_ should _ be ignored by MD037.
+
+Escaped underscores _ should \_ be ignored by MD037.
+
+Escaped underscores \__ should __ be ignored by MD037.
+
+Escaped underscores _\_ should __ be ignored by MD037.
+
+Escaped underscores __ should \__ be ignored by MD037.
+
+Escaped underscores __ should _\_ be ignored by MD037.