add antlr source code and ReadMeHEADmain

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diff --git a/antlr4-cpp-runtime-4.9.2-source/runtime/src/tree/xpath/XPath.h b/antlr4-cpp-runtime-4.9.2-source/runtime/src/tree/xpath/XPath.h
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+/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
+ */
+
+#pragma once
+
+#include "antlr4-common.h"
+
+namespace antlr4 {
+namespace tree {
+namespace xpath {
+
+  /// Represent a subset of XPath XML path syntax for use in identifying nodes in
+  /// parse trees.
+  ///
+  /// <para>
+  /// Split path into words and separators {@code /} and {@code //} via ANTLR
+  /// itself then walk path elements from left to right. At each separator-word
+  /// pair, find set of nodes. Next stage uses those as work list.</para>
+  ///
+  /// <para>
+  /// The basic interface is
+  /// <seealso cref="XPath#findAll ParseTree.findAll"/>{@code (tree, pathString, parser)}.
+  /// But that is just shorthand for:</para>
+  ///
+  /// <pre>
+  /// <seealso cref="XPath"/> p = new <seealso cref="XPath#XPath XPath"/>(parser, pathString);
+  /// return p.<seealso cref="#evaluate evaluate"/>(tree);
+  /// </pre>
+  ///
+  /// <para>
+  /// See {@code org.antlr.v4.test.TestXPath} for descriptions. In short, this
+  /// allows operators:</para>
+  ///
+  /// <dl>
+  /// <dt>/</dt> <dd>root</dd>
+  /// <dt>//</dt> <dd>anywhere</dd>
+  /// <dt>!</dt> <dd>invert; this must appear directly after root or anywhere
+  /// operator</dd>
+  /// </dl>
+  ///
+  /// <para>
+  /// and path elements:</para>
+  ///
+  /// <dl>
+  /// <dt>ID</dt> <dd>token name</dd>
+  /// <dt>'string'</dt> <dd>any string literal token from the grammar</dd>
+  /// <dt>expr</dt> <dd>rule name</dd>
+  /// <dt>*</dt> <dd>wildcard matching any node</dd>
+  /// </dl>
+  ///
+  /// <para>
+  /// Whitespace is not allowed.</para>
+
+  class ANTLR4CPP_PUBLIC XPath {
+  public:
+    static const std::string WILDCARD; // word not operator/separator
+    static const std::string NOT; // word for invert operator
+
+    XPath(Parser *parser, const std::string &path);
+    virtual ~XPath() {}
+
+    // TODO: check for invalid token/rule names, bad syntax
+    virtual std::vector<std::unique_ptr<XPathElement>> split(const std::string &path);
+
+    static std::vector<ParseTree *> findAll(ParseTree *tree, std::string const& xpath, Parser *parser);
+
+    /// Return a list of all nodes starting at {@code t} as root that satisfy the
+    /// path. The root {@code /} is relative to the node passed to
+    /// <seealso cref="#evaluate"/>.
+    virtual std::vector<ParseTree *> evaluate(ParseTree *t);
+
+  protected:
+    std::string _path;
+    Parser *_parser;
+
+    /// Convert word like {@code *} or {@code ID} or {@code expr} to a path
+    /// element. {@code anywhere} is {@code true} if {@code //} precedes the
+    /// word.
+    virtual std::unique_ptr<XPathElement> getXPathElement(Token *wordToken, bool anywhere);
+  };
+
+} // namespace xpath
+} // namespace tree
+} // namespace antlr4