content: 
  import React from 'react'
  import SlateTypes from 'slate-prop-types'
  import Types from 'prop-types'
  
  /**
   * Default placeholder.
   *
   * @type {Component}
   */
  
  class DefaultPlaceholder extends React.Component {
  
    /**
     * Property types.
     *
     * @type {Object}
     */
  
    static propTypes = {
      editor: Types.object.isRequired,
      isSelected: Types.bool.isRequired,
      node: SlateTypes.node.isRequired,
      parent: SlateTypes.node.isRequired,
      readOnly: Types.bool.isRequired,
      state: SlateTypes.state.isRequired,
    }
  
    /**
     * Render.
     *
     * @return {Element}
     */
  
    render() {
      const { editor, state } = this.props
      if (!editor.props.placeholder) return null
      if (state.document.getBlocks().size > 1) return null
  
      const style = {
        pointerEvents: 'none',
        display: 'inline-block',
        width: '0',
        maxWidth: '100%',
        whiteSpace: 'nowrap',
        opacity: '0.333',
      }
  
      return (
        <span contentEditable={false} style={style}>
          {editor.props.placeholder}
        </span>
      )
    }
  
  }
  
  /**
   * Export.
   *
   * @type {Component}
   */
  
  export default DefaultPlaceholder
  