Add a better initial source

Author: kddnewton

src/index.tsx

@@ -1,6 +1,7 @@
 import React, { Suspense, useState } from "react";
 import { createRoot } from "react-dom/client";
 
+import initialSource from "./initialSource";
 import Editor from "./Editor";
 const Tree = React.lazy(() => import("./Tree"));
 
@@ -13,7 +14,7 @@ const TreeFallback: React.FC<TreeFallbackProps> = ({ cols }) => (
 );
 
 const App: React.FC = () => {
-  const [source, setSource] = useState<string>("1 + 2");
+  const [source, setSource] = useState<string>(initialSource);
   const cols = 80;
 
   return (

src/initialSource.ts

@@ -0,0 +1,61 @@
+const initialSource = `# frozen_string_literal: true
+
+require "json"
+require "pp"
+require "prettyprint"
+require "ripper"
+require "stringio"
+
+require_relative "syntax_tree/formatter"
+require_relative "syntax_tree/node"
+require_relative "syntax_tree/parser"
+require_relative "syntax_tree/prettyprint"
+require_relative "syntax_tree/version"
+require_relative "syntax_tree/visitor"
+require_relative "syntax_tree/visitor/json_visitor"
+require_relative "syntax_tree/visitor/pretty_print_visitor"
+
+module SyntaxTree
+  # This holds references to objects that respond to both #parse and #format
+  # so that we can use them in the CLI.
+  HANDLERS = {}
+  HANDLERS.default = SyntaxTree
+
+  # This is a hook provided so that plugins can register themselves as the
+  # handler for a particular file type.
+  def self.register_handler(extension, handler)
+    HANDLERS[extension] = handler
+  end
+
+  # Parses the given source and returns the syntax tree.
+  def self.parse(source)
+    parser = Parser.new(source)
+    response = parser.parse
+    response unless parser.error?
+  end
+
+  # Parses the given source and returns the formatted source.
+  def self.format(source)
+    formatter = Formatter.new(source, [])
+    parse(source).format(formatter)
+
+    formatter.flush
+    formatter.output.join
+  end
+
+  # Returns the source from the given filepath taking into account any potential
+  # magic encoding comments.
+  def self.read(filepath)
+    encoding =
+      File.open(filepath, "r") do |file|
+        header = file.readline
+        header += file.readline if header.start_with?("#!")
+        Ripper.new(header).tap(&:parse).encoding
+      end
+
+    File.read(filepath, encoding: encoding)
+  end
+end
+`;
+
+export default initialSource;