From 483597c82a90c4b860bef8ec977b75d20f3564e9 Mon Sep 17 00:00:00 2001
From: David Anson <david@dlaa.me>
Date: Tue, 16 Jun 2015 17:50:55 -0700
Subject: [PATCH] Cache result of forEachLine for ~4% time reduction.

---
 .eslintrc    |  2 +-
 lib/rules.js | 53 +++++++++++++++++++++++++++++-----------------------
 2 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/.eslintrc b/.eslintrc
index 753ca56d..4fcecdaf 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -12,7 +12,7 @@
     "rules": {
         "no-alert": 2,
         "no-array-constructor": 2,
-        "no-bitwise": 2,
+        "no-bitwise": 0,
         "no-caller": 2,
         "no-catch-shadow": 2,
         "no-comma-dangle": 2,
diff --git a/lib/rules.js b/lib/rules.js
index bdff6a1e..14ee4c87 100644
--- a/lib/rules.js
+++ b/lib/rules.js
@@ -38,22 +38,32 @@ function filterTokens(params, type, callback) {
 
 // Calls the provided function for each line (with context)
 function forEachLine(params, callback) {
-  // Identify lines in code blocks
-  var codeLines = [];
-  filterTokens(params, "code_block", function forToken(token) {
-    for (var i = token.map[0]; i < token.map[1]; i++) {
-      codeLines.push(i);
-    }
-  });
-  // Identify lines in code fences (with info about transitions)
-  var inFence = false;
+  if (!params.forEachLine) {
+    var lineMetadata = new Array(params.lines.length);
+    var inFence = false;
+    // Find fenced code by pattern (parser ignores "``` close fence")
+    params.lines.forEach(function forLine(line, lineIndex) {
+      var metadata = 0;
+      if (/^(```|~~~)/.test(line)) {
+        metadata = inFence ? -2 : 2;
+        inFence = !inFence;
+      } else if (inFence) {
+        metadata = 1;
+      }
+      lineMetadata[lineIndex] = metadata;
+    });
+    // Find code blocks normally
+    filterTokens(params, "code_block", function forToken(token) {
+      for (var i = token.map[0]; i < token.map[1]; i++) {
+        lineMetadata[i] = 1;
+      }
+    });
+    params.forEachLine = lineMetadata;
+  }
+  // Invoke callback
   params.lines.forEach(function forLine(line, lineIndex) {
-    var onFence = /^(```|~~~)/.test(line);
-    if (onFence) {
-      inFence = !inFence;
-    }
-    var inCodeBlock = (codeLines.indexOf(lineIndex) !== -1);
-    callback(line, lineIndex, inFence || inCodeBlock, onFence);
+    var metadata = params.forEachLine[lineIndex];
+    callback(line, lineIndex, !!metadata, (metadata >> 1));
   });
 }
 
@@ -581,13 +591,11 @@ module.exports = [
     "desc": "Fenced code blocks should be surrounded by blank lines",
     "tags": [ "code", "blank_lines" ],
     "func": function MD031(params, errors) {
-      forEachLine(params, function forLine(line, lineIndex, inCode, onFence) {
-        if (onFence &&
-            ((inCode && (lineIndex - 1 >= 0) &&
-              params.lines[lineIndex - 1].length) ||
-             (!inCode && (lineIndex + 1 < params.lines.length) &&
-              params.lines[lineIndex + 1].length))) {
-          errors.push(lineIndex + 1);
+      var lines = params.lines;
+      forEachLine(params, function forLine(line, i, inCode, onFence) {
+        if (((onFence > 0) && (i - 1 >= 0) && lines[i - 1].length) ||
+            ((onFence < 0) && (i + 1 < lines.length) && lines[i + 1].length)) {
+          errors.push(i + 1);
         }
       });
     }
@@ -610,7 +618,6 @@ module.exports = [
           }
           inList = listMarker;
         }
-        inList = inList && !onFence;
         prevLine = line;
       });
     }