feature: Add maxLineSizeInBlockForComparison to avoid OOM

Fixes #220

README.md

@@ -196,6 +196,7 @@ The HTML output accepts a Javascript object with configuration. Possible options
   - `matching`: matching level: `'lines'` for matching lines, `'words'` for matching lines and words or `'none'`, default is `none`
   - `matchWordsThreshold`: similarity threshold for word matching, default is 0.25
   - `matchingMaxComparisons`: perform at most this much comparisons for line matching a block of changes, default is `2500`
+  - `maxLineSizeInBlockForComparison`: maximum number os characters of the bigger line in a block to apply comparison, default is `200`
   - `maxLineLengthHighlight`: only perform diff changes highlight if lines are smaller than this, default is `10000`
   - `templates`: object with previously compiled templates to replace parts of the html
   - `rawTemplates`: object with raw not compiled templates to replace parts of the html

src/diff2html.js

@@ -19,6 +19,7 @@
     matching: 'none',
     matchWordsThreshold: 0.25,
     matchingMaxComparisons: 2500,
+    maxLineSizeInBlockForComparison: 200,
     maxLineLengthHighlight: 10000,
     renderNothingWhenEmpty: false
   };

src/line-by-line-printer.js

@@ -94,9 +94,17 @@
         var deleteType;
 
         var comparisons = oldLines.length * newLines.length;
-        var maxComparisons = that.config.matchingMaxComparisons || 2500;
+
-        var doMatching = comparisons < maxComparisons && (that.config.matching === 'lines' ||
+        var maxLineSizeInBlock = Math.max.apply(null,
-          that.config.matching === 'words');
+          [0].concat((oldLines.concat(newLines)).map(
+            function(elem) {
+              return elem.content.length;
+            }
+          )));
+
+        var doMatching = comparisons < that.config.matchingMaxComparisons &&
+          maxLineSizeInBlock < that.config.maxLineSizeInBlockForComparison &&
+          (that.config.matching === 'lines' || that.config.matching === 'words');
 
         if (doMatching) {
           matches = matcher(oldLines, newLines);

src/side-by-side-printer.js

@@ -96,9 +96,14 @@
         var deleteType;
 
         var comparisons = oldLines.length * newLines.length;
-        var maxComparisons = that.config.matchingMaxComparisons || 2500;
+
-        var doMatching = comparisons < maxComparisons && (that.config.matching === 'lines' ||
+        var maxLineSizeInBlock = Math.max.apply(null, (oldLines.concat(newLines)).map(function(elem) {
-          that.config.matching === 'words');
+          return elem.length;
+        }));
+
+        var doMatching = comparisons < that.config.matchingMaxComparisons &&
+          maxLineSizeInBlock < that.config.maxLineSizeInBlockForComparison &&
+          (that.config.matching === 'lines' || that.config.matching === 'words');
 
         if (doMatching) {
           matches = matcher(oldLines, newLines);

test/line-by-line-tests.js

@@ -372,23 +372,23 @@ describe('LineByLinePrinter', function() {
         '        <div class="d2h-code-line d2h-info">@@ -1 +1 @@</div>\n' +
         '    </td>\n' +
         '</tr><tr>\n' +
-        '    <td class="d2h-code-linenumber d2h-del d2h-change">\n' +
+        '    <td class="d2h-code-linenumber d2h-del">\n' +
         '      <div class="line-num1">1</div>\n' +
         '<div class="line-num2"></div>\n' +
         '    </td>\n' +
-        '    <td class="d2h-del d2h-change">\n' +
+        '    <td class="d2h-del">\n' +
-        '        <div class="d2h-code-line d2h-del d2h-change">\n' +
+        '        <div class="d2h-code-line d2h-del">\n' +
         '            <span class="d2h-code-line-prefix">-</span>\n' +
         '            <span class="d2h-code-line-ctn"><del>test</del></span>\n' +
         '        </div>\n' +
         '    </td>\n' +
         '</tr><tr>\n' +
-        '    <td class="d2h-code-linenumber d2h-ins d2h-change">\n' +
+        '    <td class="d2h-code-linenumber d2h-ins">\n' +
         '      <div class="line-num1"></div>\n' +
         '<div class="line-num2">1</div>\n' +
         '    </td>\n' +
-        '    <td class="d2h-ins d2h-change">\n' +
+        '    <td class="d2h-ins">\n' +
-        '        <div class="d2h-code-line d2h-ins d2h-change">\n' +
+        '        <div class="d2h-code-line d2h-ins">\n' +
         '            <span class="d2h-code-line-prefix">+</span>\n' +
         '            <span class="d2h-code-line-ctn"><ins>test1r</ins></span>\n' +
         '        </div>\n' +

test/side-by-side-printer-tests.js

@@ -253,11 +253,11 @@ describe('SideBySidePrinter', function() {
         '        <div class="d2h-code-side-line d2h-info">@@ -1 +1 @@</div>\n' +
         '    </td>\n' +
         '</tr><tr>\n' +
-        '    <td class="d2h-code-side-linenumber d2h-del d2h-change">\n' +
+        '    <td class="d2h-code-side-linenumber d2h-del">\n' +
         '      1\n' +
         '    </td>\n' +
-        '    <td class="d2h-del d2h-change">\n' +
+        '    <td class="d2h-del">\n' +
-        '        <div class="d2h-code-side-line d2h-del d2h-change">\n' +
+        '        <div class="d2h-code-side-line d2h-del">\n' +
         '            <span class="d2h-code-line-prefix">-</span>\n' +
         '            <span class="d2h-code-line-ctn"><del>test</del></span>\n' +
         '        </div>\n' +
@@ -277,11 +277,11 @@ describe('SideBySidePrinter', function() {
         '        <div class="d2h-code-side-line d2h-info"></div>\n' +
         '    </td>\n' +
         '</tr><tr>\n' +
-        '    <td class="d2h-code-side-linenumber d2h-ins d2h-change">\n' +
+        '    <td class="d2h-code-side-linenumber d2h-ins">\n' +
         '      1\n' +
         '    </td>\n' +
-        '    <td class="d2h-ins d2h-change">\n' +
+        '    <td class="d2h-ins">\n' +
-        '        <div class="d2h-code-side-line d2h-ins d2h-change">\n' +
+        '        <div class="d2h-code-side-line d2h-ins">\n' +
         '            <span class="d2h-code-line-prefix">+</span>\n' +
         '            <span class="d2h-code-line-ctn"><ins>test1r</ins></span>\n' +
         '        </div>\n' +