Added support of operational transformation

1 files changed, 80 insertions, 0 deletions

diff --git a/lib/ot/wrapped-operation.js b/lib/ot/wrapped-operation.js
new file mode 100644
index 00000000..91050f4e
--- /dev/null
+++ b/lib/ot/wrapped-operation.js
@@ -0,0 +1,80 @@
+if (typeof ot === 'undefined') {
+  // Export for browsers
+  var ot = {};
+}
+
+ot.WrappedOperation = (function (global) {
+  'use strict';
+
+  // A WrappedOperation contains an operation and corresponing metadata.
+  function WrappedOperation (operation, meta) {
+    this.wrapped = operation;
+    this.meta    = meta;
+  }
+
+  WrappedOperation.prototype.apply = function () {
+    return this.wrapped.apply.apply(this.wrapped, arguments);
+  };
+
+  WrappedOperation.prototype.invert = function () {
+    var meta = this.meta;
+    return new WrappedOperation(
+      this.wrapped.invert.apply(this.wrapped, arguments),
+      meta && typeof meta === 'object' && typeof meta.invert === 'function' ?
+        meta.invert.apply(meta, arguments) : meta
+    );
+  };
+
+  // Copy all properties from source to target.
+  function copy (source, target) {
+    for (var key in source) {
+      if (source.hasOwnProperty(key)) {
+        target[key] = source[key];
+      }
+    }
+  }
+
+  function composeMeta (a, b) {
+    if (a && typeof a === 'object') {
+      if (typeof a.compose === 'function') { return a.compose(b); }
+      var meta = {};
+      copy(a, meta);
+      copy(b, meta);
+      return meta;
+    }
+    return b;
+  }
+
+  WrappedOperation.prototype.compose = function (other) {
+    return new WrappedOperation(
+      this.wrapped.compose(other.wrapped),
+      composeMeta(this.meta, other.meta)
+    );
+  };
+
+  function transformMeta (meta, operation) {
+    if (meta && typeof meta === 'object') {
+      if (typeof meta.transform === 'function') {
+        return meta.transform(operation);
+      }
+    }
+    return meta;
+  }
+
+  WrappedOperation.transform = function (a, b) {
+    var transform = a.wrapped.constructor.transform;
+    var pair = transform(a.wrapped, b.wrapped);
+    return [
+      new WrappedOperation(pair[0], transformMeta(a.meta, b.wrapped)),
+      new WrappedOperation(pair[1], transformMeta(b.meta, a.wrapped))
+    ];
+  };
+
+  return WrappedOperation;
+
+}(this));
+
+// Export for CommonJS
+if (typeof module === 'object') {
+  module.exports = ot.WrappedOperation;
+}
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