Examples of ParseTreePatternMatcher

org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher
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:

{@code = ;}

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 } matchesany {@code ID} token and tag {@code } 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 patternexcept that it requires the identifier to be {@code x} and the expression tobe {@code 0}.

The {@link #matches} routines return {@code true} or {@code false} basedupon a match for the tree rooted at the parameter sent in. The {@link #match} routines return a {@link ParseTreeMatch} object thatcontains 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 notmatch.

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} thatare easy to use but not super efficient because they create new {@link ParseTreePatternMatcher} objects each time and have to compile thepattern 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 = ;} into a sequence of four tokens (assuming lexerthrows 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-definedfields 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 } as a valid{@code expr} but, from the parser passed in, we create a special version ofthe underlying grammar representation (an {@link ATN}) that allows imaginary tokens representing rules ( {@code }) to match entire rules. We call these bypass alternatives.

Delimiters are {@code <} and {@code>}, with {@code \} as the escape stringby default, but you can set them to whatever you want using {@link #setDelimiters}. You must escape both start and stop strings {@code \<} and {@code \>}.

Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

   * {@link Lexer} rather than trying to deduce it from this parser.
   */
  public ParseTreePattern compileParseTreePattern(String pattern, int patternRuleIndex,
                          Lexer lexer)
  {
    ParseTreePatternMatcher m = new ParseTreePatternMatcher(lexer, this);
    return m.compile(pattern, patternRuleIndex);
  }

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;


public class TestParseTreeMatcher extends BaseTest {
  @Test public void testChunking() throws Exception {
    ParseTreePatternMatcher m = new ParseTreePatternMatcher(null, null);
    assertEquals("[ID, ' = ', expr, ' ;']", m.split("<ID> = <expr> ;").toString());
    assertEquals("[' ', ID, ' = ', expr]", m.split(" <ID> = <expr>").toString());
    assertEquals("[ID, ' = ', expr]", m.split("<ID> = <expr>").toString());
    assertEquals("[expr]", m.split("<expr>").toString());
    assertEquals("['<x> foo']", m.split("\\<x\\> foo").toString());
    assertEquals("['foo <x> bar ', tag]", m.split("foo \\<x\\> bar <tag>").toString());
  }

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

    assertEquals("['<x> foo']", m.split("\\<x\\> foo").toString());
    assertEquals("['foo <x> bar ', tag]", m.split("foo \\<x\\> bar <tag>").toString());
  }


  @Test public void testDelimiters() throws Exception {
    ParseTreePatternMatcher m = new ParseTreePatternMatcher(null, null);
    m.setDelimiters("<<", ">>", "$");
    String result = m.split("<<ID>> = <<expr>> ;$<< ick $>>").toString();
    assertEquals("[ID, ' = ', expr, ' ;<< ick >>']", result);
  }

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

    String result = m.split("<<ID>> = <<expr>> ;$<< ick $>>").toString();
    assertEquals("[ID, ' = ', expr, ' ;<< ick >>']", result);
  }


  @Test public void testInvertedTags() throws Exception {
    ParseTreePatternMatcher m= new ParseTreePatternMatcher(null, null);
    String result = null;
    try {
      m.split(">expr<");
    }
    catch (IllegalArgumentException iae) {
      result = iae.getMessage();
    }
    String expected = "tag delimiters out of order in pattern: >expr<";

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

    String expected = "tag delimiters out of order in pattern: >expr<";
    assertEquals(expected, result);
  }


  @Test public void testUnclosedTag() throws Exception {
    ParseTreePatternMatcher m = new ParseTreePatternMatcher(null, null);
    String result = null;
    try {
      m.split("<expr hi mom");
    }
    catch (IllegalArgumentException iae) {
      result = iae.getMessage();
    }
    String expected = "unterminated tag in pattern: <expr hi mom";

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

    String expected = "unterminated tag in pattern: <expr hi mom";
    assertEquals(expected, result);
  }


  @Test public void testExtraClose() throws Exception {
    ParseTreePatternMatcher m = new ParseTreePatternMatcher(null, null);
    String result = null;
    try {
      m.split("<expr> >");
    }
    catch (IllegalArgumentException iae) {
      result = iae.getMessage();
    }
    String expected = "missing start tag in pattern: <expr> >";

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

      "WS : [ \\r\\n\\t]+ -> skip ;\n";
    boolean ok =
      rawGenerateAndBuildRecognizer("X1.g4", grammar, "X1Parser", "X1Lexer", false);
    assertTrue(ok);


    ParseTreePatternMatcher m = getPatternMatcher("X1");


    List<? extends Token> tokens = m.tokenize("<ID> = <expr> ;");
    String results = tokens.toString();
    String expected = "[ID:3, [@-1,1:1='=',<1>,1:1], expr:7, [@-1,1:1=';',<2>,1:1]]";
    assertEquals(expected, results);
  }

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

      "WS : [ \\r\\n\\t]+ -> skip ;\n";
    boolean ok =
      rawGenerateAndBuildRecognizer("X2.g4", grammar, "X2Parser", "X2Lexer", false);
    assertTrue(ok);


    ParseTreePatternMatcher m = getPatternMatcher("X2");


    ParseTreePattern t = m.compile("<ID> = <expr> ;", m.getParser().getRuleIndex("s"));
    String results = t.getPatternTree().toStringTree(m.getParser());
    String expected = "(s <ID> = (expr <expr>) ;)";
    assertEquals(expected, results);
  }

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

      "WS : [ \\r\\n\\t]+ -> skip ;\n";
    boolean ok =
      rawGenerateAndBuildRecognizer("X2.g4", grammar, "X2Parser", "X2Lexer", false);
    assertTrue(ok);


    ParseTreePatternMatcher m = getPatternMatcher("X2");


    boolean failed = false;
    try {
      m.compile("<ID> = <expr> ; extra", m.getParser().getRuleIndex("s"));
    }
    catch (ParseTreePatternMatcher.StartRuleDoesNotConsumeFullPattern e) {
      failed = true;
    }
    assertTrue(failed);

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Examples of org.antlr.v4.runtime.tree.pattern.ParseTreePatternMatcher

      "WS : [ \\r\\n\\t]+ -> skip ;\n";
    boolean ok =
      rawGenerateAndBuildRecognizer("X2.g4", grammar, "X2Parser", "X2Lexer", false);
    assertTrue(ok);


    ParseTreePatternMatcher m = getPatternMatcher("X2");


    boolean failed = false;
    try {
      m.compile("<ID> ;", m.getParser().getRuleIndex("s"));
    }
    catch (InputMismatchException e) {
      failed = true;
    }
    assertTrue(failed);

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