Constructs a {@link ParseTreePatternMatcher} or from a {@link Lexer} and {@link 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.
For repeated use of a tree pattern, compile it to a {@link ParseTreePattern} using this method.
Used to convert the tree pattern string into a series of tokens. The input stream is reset.
Used to collect to the grammar file name, token names, rule names for used to parse the pattern into a parse tree.
Compare {@code pattern} matched as rule {@code patternRuleIndex} against {@code tree} and return a {@link ParseTreeMatch} object that contains the matched elements, or the node at which the match failed.
Compare {@code pattern} matched against {@code tree} and return a {@link ParseTreeMatch} object that contains the matched elements, or thenode at which the match failed. Pass in a compiled pattern instead of a string representation of a tree pattern.
Recursively walk {@code tree} against {@code patternTree}, filling {@code match.}{@link ParseTreeMatch#labels labels}.
Does {@code pattern} matched as rule {@code patternRuleIndex} match {@code tree}?
Does {@code pattern} matched as rule patternRuleIndex match tree? Pass in a compiled pattern instead of a string representation of a tree pattern.
Set the delimiters used for marking rule and token tags within concrete syntax used by the tree pattern parser.
Split {@code <ID> = <e:expr> ;} into 4 chunks for tokenizing by {@link #tokenize}.
A tree pattern matching mechanism for ANTLR {@link ParseTree}s.
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 {@link ParseTree} with placeholders for the {@code ID} and {@code expr} subtree. Then the {@link #match} routines can compare an actual {@link 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}).
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}.
The {@link #matches} routines return {@code true} or {@code false} based upon a match for the tree rooted at the parameter sent in. The {@link #match} routines return a {@link 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 {@link ParseTreeMatch#mismatchedNode} set to the first tree node that did not match.
For efficiency, you can compile a tree pattern in string form to a {@link ParseTreePattern} object.
See {@code TestParseTreeMatcher} for lots of examples. {@link ParseTreePattern} has two static helper methods: {@link ParseTreePattern#findAll} and {@link ParseTreePattern#match} that are easy to use but not super efficient because they create new {@link ParseTreePatternMatcher} objects each time and have to compile the pattern in string form before using it.
The lexer and parser that you pass into the {@link 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 {@link 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.
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 {@link ATN}) that allows imaginary tokens representing rules ({@code <expr>}) to match entire rules. We call these <em>bypass alternatives</em>.
Delimiters are {@code <} and {@code >}, with {@code \} as the escape string by default, but you can set them to whatever you want using {@link #setDelimiters}. You must escape both start and stop strings {@code \<} and {@code \>}.