1 files changed, 141 insertions, 0 deletions
diff --git a/packages/gitbook-core/src/components/Dropdown.js b/packages/gitbook-core/src/components/Dropdown.js
new file mode 100644
index 0000000..f43a6fc
--- /dev/null
+++ b/packages/gitbook-core/src/components/Dropdown.js
@@ -0,0 +1,141 @@
+const React      = require('react');
+const classNames = require('classnames');
+
+const Backdrop = require('./Backdrop');
+
+/**
+ * Dropdown to display a menu
+ *
+ * <Dropdown.Container>
+ *
+ *     <Button />
+ *
+ *     <Dropdown.Menu open={this.state.open}>
+ *         <Dropdown.Item href={...}> ... </Dropdown.Item>
+ *         <Dropdown.Item onClick={...}> ... </Dropdown.Item>
+ *
+ *         <Dropdown.Item> A submenu
+ *              <Dropdown.Menu>
+ *                  <Dropdown.Item href={...}> Subitem </Dropdown.Item>
+ *              </Dropdown.Menu>
+ *         </Dropdown.Item>
+ *
+ *     </Dropdown.Menu>
+ * </Dropdown.Container>
+ */
+
+const DropdownContainer = React.createClass({
+    propTypes: {
+        className:  React.PropTypes.string,
+        span: React.PropTypes.bool,
+        children: React.PropTypes.node
+    },
+
+    render() {
+        let { className, span, children } = this.props;
+
+        className = classNames(
+            'GitBook-Dropdown',
+            className
+        );
+
+        return span ?
+               <span className={className}>{children}</span>
+             : <div className={className}>{children}</div>;
+    }
+});
+
+/**
+ * A dropdown item, which is always a link, and can contain a nested
+ * DropdownMenu.
+ */
+const DropdownItem = React.createClass({
+    propTypes: {
+        children:  React.PropTypes.node,
+        onClick:   React.PropTypes.func,
+        href:      React.PropTypes.string
+    },
+
+    onClick(e) {
+        if (!this.props.href) {
+            e.preventDefault();
+            e.stopPropagation();
+
+            if (this.props.onClick) this.props.onClick();
+        }
+    },
+
+    render() {
+        const {
+            children, href,
+            onClick, // eslint-disable-line no-unused-vars
+            ...otherProps
+        } = this.props;
+
+        let inner = [], submenu = [];
+        submenu = filterChildren(children, isDropdownMenu);
+        inner = filterChildren(children, (child) => !isDropdownMenu(child));
+
+        return (
+            <li className="GitBook-DropdownItem">
+                <a href={href || '#'}
+                   onClick={this.onClick}
+                   {...otherProps} >
+                    {inner}
+                </a>
+                {submenu}
+            </li>
+        );
+    }
+});
+
+/**
+ * @param {Node} children
+ * @param {Function} predicate
+ * @return {Node} children that pass the predicate
+ */
+function filterChildren(children, predicate) {
+    return React.Children.map(
+        children,
+        (child) => predicate(child) ? child : null
+    );
+}
+
+/**
+ * A DropdownMenu to display DropdownItems. Must be inside a
+ * DropdownContainer.
+ */
+const DropdownMenu = React.createClass({
+    propTypes: {
+        className: React.PropTypes.string,
+        children:  React.PropTypes.node,
+        open:      React.PropTypes.bool
+    },
+
+    render() {
+        const { open } = this.props;
+        const className = classNames(
+            'GitBook-DropdownMenu',
+            { 'GitBook-DropdownMenu-open': open }
+        );
+
+        return (
+            <ul className={className}>
+                {this.props.children}
+            </ul>
+        );
+    }
+});
+
+function isDropdownMenu(child) {
+    return (child && child.type && child.type.displayName === 'DropdownMenu');
+}
+
+const Dropdown = {
+    Item: DropdownItem,
+    Menu: DropdownMenu,
+    Container: DropdownContainer,
+    Backdrop
+};
+
+module.exports = Dropdown;