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