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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 "Exceptions.h"
namespace antlr4 {
namespace tree {
namespace pattern {
/// <summary>
/// A tree pattern matching mechanism for ANTLR <seealso cref="ParseTree"/>s.
/// <p/>
/// Patterns are strings of source input text with special tags representing
/// token or rule references such as:
/// <p/>
/// {@code <ID> = <expr>;}
/// <p/>
/// Given a pattern start rule such as {@code statement}, this object constructs
/// a <seealso cref="ParseTree"/> with placeholders for the {@code ID} and {@code expr}
/// subtree. Then the <seealso cref="#match"/> routines can compare an actual
/// <seealso cref="ParseTree"/> from a parse with this pattern. Tag {@code <ID>} matches
/// any {@code ID} token and tag {@code <expr>} references the result of the
/// {@code expr} rule (generally an instance of {@code ExprContext}.
/// <p/>
/// Pattern {@code x = 0;} is a similar pattern that matches the same pattern
/// except that it requires the identifier to be {@code x} and the expression to
/// be {@code 0}.
/// <p/>
/// The <seealso cref="#matches"/> routines return {@code true} or {@code false} based
/// upon a match for the tree rooted at the parameter sent in. The
/// <seealso cref="#match"/> routines return a <seealso cref="ParseTreeMatch"/> object that
/// contains the parse tree, the parse tree pattern, and a map from tag name to
/// matched nodes (more below). A subtree that fails to match, returns with
/// <seealso cref="ParseTreeMatch#mismatchedNode"/> set to the first tree node that did not
/// match.
/// <p/>
/// For efficiency, you can compile a tree pattern in string form to a
/// <seealso cref="ParseTreePattern"/> object.
/// <p/>
/// See {@code TestParseTreeMatcher} for lots of examples.
/// <seealso cref="ParseTreePattern"/> has two static helper methods:
/// <seealso cref="ParseTreePattern#findAll"/> and <seealso cref="ParseTreePattern#match"/> that
/// are easy to use but not super efficient because they create new
/// <seealso cref="ParseTreePatternMatcher"/> objects each time and have to compile the
/// pattern in string form before using it.
/// <p/>
/// The lexer and parser that you pass into the <seealso cref="ParseTreePatternMatcher"/>
/// constructor are used to parse the pattern in string form. The lexer converts
/// the {@code <ID> = <expr>;} into a sequence of four tokens (assuming lexer
/// throws out whitespace or puts it on a hidden channel). Be aware that the
/// input stream is reset for the lexer (but not the parser; a
/// <seealso cref="ParserInterpreter"/> is created to parse the input.). Any user-defined
/// fields you have put into the lexer might get changed when this mechanism asks
/// it to scan the pattern string.
/// <p/>
/// Normally a parser does not accept token {@code <expr>} as a valid
/// {@code expr} but, from the parser passed in, we create a special version of
/// the underlying grammar representation (an <seealso cref="ATN"/>) that allows imaginary
/// tokens representing rules ({@code <expr>}) to match entire rules. We call
/// these <em>bypass alternatives</em>.
/// <p/>
/// Delimiters are {@code <} and {@code >}, with {@code \} as the escape string
/// by default, but you can set them to whatever you want using
/// <seealso cref="#setDelimiters"/>. You must escape both start and stop strings
/// {@code \<} and {@code \>}.
/// </summary>
class ANTLR4CPP_PUBLIC ParseTreePatternMatcher {
public:
class CannotInvokeStartRule : public RuntimeException {
public:
CannotInvokeStartRule(const RuntimeException &e);
~CannotInvokeStartRule();
};
// Fixes https://github.com/antlr/antlr4/issues/413
// "Tree pattern compilation doesn't check for a complete parse"
class StartRuleDoesNotConsumeFullPattern : public RuntimeException {
public:
StartRuleDoesNotConsumeFullPattern() = default;
StartRuleDoesNotConsumeFullPattern(StartRuleDoesNotConsumeFullPattern const&) = default;
~StartRuleDoesNotConsumeFullPattern();
StartRuleDoesNotConsumeFullPattern& operator=(StartRuleDoesNotConsumeFullPattern const&) = default;
};
/// Constructs a <seealso cref="ParseTreePatternMatcher"/> or from a <seealso cref="Lexer"/> and
/// <seealso cref="Parser"/> object. The lexer input stream is altered for tokenizing
/// the tree patterns. The parser is used as a convenient mechanism to get
/// the grammar name, plus token, rule names.
ParseTreePatternMatcher(Lexer *lexer, Parser *parser);
virtual ~ParseTreePatternMatcher();
/// <summary>
/// Set the delimiters used for marking rule and token tags within concrete
/// syntax used by the tree pattern parser.
/// </summary>
/// <param name="start"> The start delimiter. </param>
/// <param name="stop"> The stop delimiter. </param>
/// <param name="escapeLeft"> The escape sequence to use for escaping a start or stop delimiter.
/// </param>
/// <exception cref="IllegalArgumentException"> if {@code start} is {@code null} or empty. </exception>
/// <exception cref="IllegalArgumentException"> if {@code stop} is {@code null} or empty. </exception>
virtual void setDelimiters(const std::string &start, const std::string &stop, const std::string &escapeLeft);
/// <summary>
/// Does {@code pattern} matched as rule {@code patternRuleIndex} match {@code tree}? </summary>
virtual bool matches(ParseTree *tree, const std::string &pattern, int patternRuleIndex);
/// <summary>
/// Does {@code pattern} matched as rule patternRuleIndex match tree? Pass in a
/// compiled pattern instead of a string representation of a tree pattern.
/// </summary>
virtual bool matches(ParseTree *tree, const ParseTreePattern &pattern);
/// <summary>
/// Compare {@code pattern} matched as rule {@code patternRuleIndex} against
/// {@code tree} and return a <seealso cref="ParseTreeMatch"/> object that contains the
/// matched elements, or the node at which the match failed.
/// </summary>
virtual ParseTreeMatch match(ParseTree *tree, const std::string &pattern, int patternRuleIndex);
/// <summary>
/// Compare {@code pattern} matched against {@code tree} and return a
/// <seealso cref="ParseTreeMatch"/> object that contains the matched elements, or the
/// node at which the match failed. Pass in a compiled pattern instead of a
/// string representation of a tree pattern.
/// </summary>
virtual ParseTreeMatch match(ParseTree *tree, const ParseTreePattern &pattern);
/// <summary>
/// For repeated use of a tree pattern, compile it to a
/// <seealso cref="ParseTreePattern"/> using this method.
/// </summary>
virtual ParseTreePattern compile(const std::string &pattern, int patternRuleIndex);
/// <summary>
/// Used to convert the tree pattern string into a series of tokens. The
/// input stream is reset.
/// </summary>
virtual Lexer* getLexer();
/// <summary>
/// Used to collect to the grammar file name, token names, rule names for
/// used to parse the pattern into a parse tree.
/// </summary>
virtual Parser* getParser();
// ---- SUPPORT CODE ----
virtual std::vector<std::unique_ptr<Token>> tokenize(const std::string &pattern);
/// Split "<ID> = <e:expr>;" into 4 chunks for tokenizing by tokenize().
virtual std::vector<Chunk> split(const std::string &pattern);
protected:
std::string _start;
std::string _stop;
std::string _escape; // e.g., \< and \> must escape BOTH!
/// Recursively walk {@code tree} against {@code patternTree}, filling
/// {@code match.}<seealso cref="ParseTreeMatch#labels labels"/>.
///
/// <returns> the first node encountered in {@code tree} which does not match
/// a corresponding node in {@code patternTree}, or {@code null} if the match
/// was successful. The specific node returned depends on the matching
/// algorithm used by the implementation, and may be overridden. </returns>
virtual ParseTree* matchImpl(ParseTree *tree, ParseTree *patternTree, std::map<std::string, std::vector<ParseTree *>> &labels);
/// Is t <expr> subtree?
virtual RuleTagToken* getRuleTagToken(ParseTree *t);
private:
Lexer *_lexer;
Parser *_parser;
void InitializeInstanceFields();
};
} // namespace pattern
} // namespace tree
} // namespace antlr4
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