add unwrap transform

lib/models/node.js

@@ -922,12 +922,52 @@ const Node = {
     })
 
     return node.normalize()
-  }
+  },
 
   /**
-   * Unwrap the node
+   * Unwrap all of the block nodes in a `range` from a parent node of `type.`
+   *
+   * @param {Selection} range
+   * @param {String} type
+   * @return {Node} node
    */
 
+  unwrapAtRange(range, type) {
+    range = range.normalize(this)
+    let node = this
+    let blocks = node.getBlockNodesAtRange(range)
+
+    // Iterate each of the block nodes, unwrapping them.
+    blocks.forEach((block) => {
+      let wrapper = node.getParentNode(block)
+      while (wrapper && wrapper.type != type) {
+        wrapper = node.getParentNode(wrapper)
+      }
+
+      // If no wrapper was found, do skip this block.
+      if (!wrapper) return
+
+      // Take the child nodes of the wrapper, and move them to the block.
+      const isDirectChild = node.nodes.has(wrapper.key)
+      let parent = isDirectChild ? node : node.getParentNode(wrapper)
+
+      // Replace the wrapper in the parent's nodes with the block.
+      const nodes = parent.nodes.takeUntil(node => node == wrapper)
+        .set(block.key, block)
+        .concat(parent.nodes.skipUntil(node => node == wrapper).rest())
+
+      // Update the parent.
+      if (isDirectChild) {
+        node = node.merge({ nodes })
+      } else {
+        parent = parent.merge({ nodes })
+        node = node.updateNode(parent)
+      }
+    })
+
+    return node.normalize()
+  }
+
 }
 
 /**

lib/models/state.js

@@ -353,6 +353,22 @@ class State extends Record(DEFAULTS) {
     return state
   }
 
+  /**
+   * Unwrap the block nodes in the current selection from a parent of `type`.
+   *
+   * @param {String} type
+   * @return {State} state
+   */
+
+  unwrap(type) {
+    let state = this
+    let { document, selection } = state
+    selection = selection.normalize(document)
+    document = document.unwrapAtRange(selection, type)
+    state = state.merge({ document, selection })
+    return state
+  }
+
 }
 
 /**