tree compare

src/js/git/treeCompare.js

@@ -0,0 +1,89 @@
+// static class...
+function LevelEngine() {
+
+}
+
+LevelEngine.prototype.compareBranchesWithinTrees = function(treeA, treeB, branches) {
+  var result = true;
+  _.each(branches, function(branchName) {
+    result = result && this.compareBranchWithinTrees(treeA, treeB, branchName);
+  }, this);
+
+  return result;
+};
+
+LevelEngine.prototype.compareBranchWithinTrees = function(treeA, treeB, branchName) {
+  treeA = this.convertTreeSafe(treeA);
+  treeB = this.convertTreeSafe(treeB);
+
+  this.stripTreeFields([treeA, treeB]);
+
+  // we need a recursive comparison function to bubble up the  branch
+  var recurseCompare = function(commitA, commitB) {
+    // this is the short-circuit base case
+    var result = _.isEqual(commitA, commitB);
+    if (!result) {
+      return false;
+    }
+
+    // we loop through each parent ID. we sort the parent ID's beforehand
+    // so the index lookup is valid
+    _.each(commitA.parents, function(pAid, index) {
+      var pBid = commitB.parents[index];
+
+      var childA = treeA.commits[pAid];
+      var childB = treeB.commits[pBid];
+
+      result = result && recurseCompare(childA, childB);
+    }, this);
+    // if each of our children recursively are equal, we are good
+    return result;
+  };
+
+  var branchA = treeA.branches[branchName];
+  var branchB = treeB.branches[branchName];
+
+  return _.isEqual(branchA, branchB) &&
+    recurseCompare(treeA.commits[branchA.target], treeB.commits[branchB.target]);
+};
+
+LevelEngine.prototype.convertTreeSafe = function(tree) {
+  if (typeof tree == 'string') {
+    return JSON.parse(unescape(tree));
+  }
+  return tree;
+};
+
+LevelEngine.prototype.stripTreeFields = function(trees) {
+  var stripFields = ['createTime', 'author', 'commitMessage'];
+  var sortFields = ['children', 'parents'];
+
+  _.each(trees, function(tree) {
+    _.each(tree.commits, function(commit) {
+      _.each(stripFields, function(field) {
+        commit[field] = undefined;
+      });
+      _.each(sortFields, function(field) {
+        if (commit[field]) {
+          commit[field] = commit[field].sort();
+        }
+      });
+    });
+  });
+};
+
+LevelEngine.prototype.compareTrees = function(treeA, treeB) {
+  treeA = this.convertTreeSafe(treeA);
+  treeB = this.convertTreeSafe(treeB);
+
+  // now we need to strip out the fields we don't care about, aka things
+  // like createTime, message, author
+  this.stripTreeFields([treeA, treeB]);
+
+  return _.isEqual(treeA, treeB);
+};
+
+var levelEngine = new LevelEngine();
+
+exports.LevelEngine = LevelEngine;
+