SONARPY-917 Match / case statement: support wildcard and group patterns (#991)

Author: andrea-guarino-sonarsource

python-frontend/src/main/java/org/sonar/plugins/python/api/tree/BaseTreeVisitor.java

@@ -518,6 +518,16 @@ public void visitSequencePattern(SequencePattern sequencePattern) {
 
   @Override
   public void visitStarPattern(StarPattern starPattern) {
-    scan(starPattern.capturePattern());
+    scan(starPattern.pattern());
+  }
+
+  @Override
+  public void visitWildcardPattern(WildcardPattern wildcardPattern) {
+    // noop
+  }
+
+  @Override
+  public void visitGroupPattern(GroupPattern groupPattern) {
+    scan(groupPattern.pattern());
   }
 }

python-frontend/src/main/java/org/sonar/plugins/python/api/tree/GroupPattern.java

@@ -0,0 +1,36 @@
+/*
+ * SonarQube Python Plugin
+ * Copyright (C) 2011-2021 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.plugins.python.api.tree;
+
+/**
+ * Group Pattern
+ * <pre> case ({@link #pattern()}): ...</pre>
+ *
+ * See https://docs.python.org/3/reference/compound_stmts.html#group-patterns
+ */
+public interface GroupPattern extends Pattern {
+
+  Token leftPar();
+
+  Pattern pattern();
+
+  Token rightPar();
+
+}

python-frontend/src/main/java/org/sonar/plugins/python/api/tree/StarPattern.java

@@ -32,5 +32,8 @@
  */
 public interface StarPattern extends Pattern {
 
-  CapturePattern capturePattern();
+  /**
+   * Return value can only be either {@link CapturePattern} or {@link WildcardPattern}
+   */
+  Pattern pattern();
 }

python-frontend/src/main/java/org/sonar/plugins/python/api/tree/Tree.java

@@ -100,6 +100,8 @@ enum Kind {
 
     GLOBAL_STMT(GlobalStatement.class),
 
+    GROUP_PATTERN(GroupPattern.class),
+
     GUARD(Guard.class),
 
     IF_STMT(IfStatement.class),
@@ -169,6 +171,8 @@ enum Kind {
 
     WHILE_STMT(WhileStatement.class),
 
+    WILDCARD_PATTERN(WildcardPattern.class),
+
     WITH_ITEM(WithItem.class),
 
     WITH_STMT(WithStatement.class),

python-frontend/src/main/java/org/sonar/plugins/python/api/tree/TreeVisitor.java

@@ -190,4 +190,8 @@ public interface TreeVisitor {
   void visitSequencePattern(SequencePattern sequencePattern);
 
   void visitStarPattern(StarPattern starPattern);
+
+  void visitWildcardPattern(WildcardPattern wildcardPattern);
+
+  void visitGroupPattern(GroupPattern groupPattern);
 }

python-frontend/src/main/java/org/sonar/plugins/python/api/tree/WildcardPattern.java

@@ -0,0 +1,32 @@
+/*
+ * SonarQube Python Plugin
+ * Copyright (C) 2011-2021 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.plugins.python.api.tree;
+
+/**
+ * Group Pattern
+ * <pre>case _: ...</pre>
+ *
+ * See https://docs.python.org/3/reference/compound_stmts.html#wildcard-patterns
+ */
+public interface WildcardPattern extends Pattern {
+
+  Token wildcard();
+
+}

python-frontend/src/main/java/org/sonar/python/api/PythonGrammar.java

@@ -166,6 +166,8 @@ public enum PythonGrammar implements GrammarRuleKey {
   MAYBE_STAR_PATTERN,
   MAYBE_SEQUENCE_PATTERN,
   OPEN_SEQUENCE_PATTERN,
+  WILDCARD_PATTERN,
+  GROUP_PATTERN,
 
   SIGNED_NUMBER,
   COMPLEX_NUMBER,
@@ -467,7 +469,7 @@ public static void compoundStatements(LexerfulGrammarBuilder b) {
 
     b.rule(PATTERNS).is(b.firstOf(OPEN_SEQUENCE_PATTERN, PATTERN));
     b.rule(PATTERN).is(b.firstOf(AS_PATTERN, OR_PATTERN));
-    b.rule(CLOSED_PATTERN).is(b.firstOf(LITERAL_PATTERN, CAPTURE_PATTERN, SEQUENCE_PATTERN));
+    b.rule(CLOSED_PATTERN).is(b.firstOf(LITERAL_PATTERN, GROUP_PATTERN, WILDCARD_PATTERN, CAPTURE_PATTERN, SEQUENCE_PATTERN));
     b.rule(AS_PATTERN).is(OR_PATTERN, "as", CAPTURE_PATTERN);
     b.rule(OR_PATTERN).is(CLOSED_PATTERN, b.zeroOrMore("|", CLOSED_PATTERN));
     b.rule(CAPTURE_PATTERN).is(NAME);
@@ -479,8 +481,7 @@ public static void compoundStatements(LexerfulGrammarBuilder b) {
     b.rule(OPEN_SEQUENCE_PATTERN).is(MAYBE_STAR_PATTERN, ",", b.optional(MAYBE_SEQUENCE_PATTERN));
     b.rule(MAYBE_SEQUENCE_PATTERN).is(MAYBE_STAR_PATTERN, b.zeroOrMore(",", MAYBE_STAR_PATTERN), b.optional(","));
     b.rule(MAYBE_STAR_PATTERN).is(b.firstOf(STAR_PATTERN, PATTERN));
-    // TODO: ADD wildcard pattern for "*_"
-    b.rule(STAR_PATTERN).is("*", CAPTURE_PATTERN);
+    b.rule(STAR_PATTERN).is("*", b.firstOf(WILDCARD_PATTERN, CAPTURE_PATTERN));
 
     b.rule(LITERAL_PATTERN).is(b.firstOf(
       COMPLEX_NUMBER,
@@ -501,6 +502,9 @@ public static void compoundStatements(LexerfulGrammarBuilder b) {
       b.sequence("-", NUMBER)
     ));
 
+    b.rule(WILDCARD_PATTERN).is("_");
+    b.rule(GROUP_PATTERN).is("(", PATTERN, ")");
+
     b.rule(FUNCDEF).is(b.optional(DECORATORS), b.optional("async"), "def", FUNCNAME, "(", b.optional(TYPEDARGSLIST), ")", b.optional(FUN_RETURN_ANNOTATION), ":", SUITE);
     b.rule(FUNCNAME).is(NAME);
     b.rule(FUN_RETURN_ANNOTATION).is("-", ">", TEST);

python-frontend/src/main/java/org/sonar/python/tree/GroupPatternImpl.java

@@ -0,0 +1,71 @@
+/*
+ * SonarQube Python Plugin
+ * Copyright (C) 2011-2021 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.python.tree;
+
+import java.util.Arrays;
+import java.util.List;
+import org.sonar.plugins.python.api.tree.GroupPattern;
+import org.sonar.plugins.python.api.tree.Pattern;
+import org.sonar.plugins.python.api.tree.Token;
+import org.sonar.plugins.python.api.tree.Tree;
+import org.sonar.plugins.python.api.tree.TreeVisitor;
+
+public class GroupPatternImpl extends PyTree implements GroupPattern {
+
+  private final Token leftPar;
+  private final Pattern pattern;
+  private final Token rightPar;
+
+  public GroupPatternImpl(Token leftPar, Pattern pattern, Token rightPar) {
+    this.leftPar = leftPar;
+    this.pattern = pattern;
+    this.rightPar = rightPar;
+  }
+
+  @Override
+  public Token leftPar() {
+    return leftPar;
+  }
+
+  @Override
+  public Pattern pattern() {
+    return pattern;
+  }
+
+  @Override
+  public Token rightPar() {
+    return rightPar;
+  }
+
+  @Override
+  public void accept(TreeVisitor visitor) {
+    visitor.visitGroupPattern(this);
+  }
+
+  @Override
+  public Kind getKind() {
+    return Kind.GROUP_PATTERN;
+  }
+
+  @Override
+  List<Tree> computeChildren() {
+    return Arrays.asList(leftPar, pattern, rightPar);
+  }
+}

python-frontend/src/main/java/org/sonar/python/tree/PythonTreeMaker.java

@@ -64,6 +64,7 @@
 import org.sonar.plugins.python.api.tree.FormattedExpression;
 import org.sonar.plugins.python.api.tree.FunctionDef;
 import org.sonar.plugins.python.api.tree.GlobalStatement;
+import org.sonar.plugins.python.api.tree.GroupPattern;
 import org.sonar.plugins.python.api.tree.Guard;
 import org.sonar.plugins.python.api.tree.IfStatement;
 import org.sonar.plugins.python.api.tree.ImportFrom;
@@ -859,10 +860,21 @@ public static Pattern closedPattern(AstNode closedPattern) {
       return new CapturePatternImpl(name(astNode.getFirstChild()));
     } else if (astNode.is(PythonGrammar.SEQUENCE_PATTERN)) {
       return sequencePattern(astNode);
+    } else if (astNode.is(PythonGrammar.GROUP_PATTERN)) {
+      return groupPattern(astNode);
+    } else if (astNode.is(PythonGrammar.WILDCARD_PATTERN)) {
+      return wildcardPattern(astNode);
     }
     throw new IllegalStateException(String.format("Pattern %s not recognized.", astNode.getName()));
   }
 
+  private static GroupPattern groupPattern(AstNode groupPattern) {
+    Token leftPar = toPyToken(groupPattern.getFirstChild(PythonPunctuator.LPARENTHESIS).getToken());
+    Pattern pattern = pattern(groupPattern.getFirstChild(PythonGrammar.PATTERN).getFirstChild());
+    Token rightPar = toPyToken(groupPattern.getFirstChild(PythonPunctuator.RPARENTHESIS).getToken());
+    return new GroupPatternImpl(leftPar, pattern, rightPar);
+  }
+
   private static SequencePattern sequencePattern(AstNode sequencePattern) {
     AstNode leftDelimiter = sequencePattern.getFirstChild(PythonPunctuator.LPARENTHESIS, PythonPunctuator.LBRACKET);
     AstNode rightDelimiter = sequencePattern.getFirstChild(PythonPunctuator.RPARENTHESIS, PythonPunctuator.RBRACKET);
@@ -911,10 +923,21 @@ private static Pattern maybeStarPattern(AstNode maybeStarPattern) {
 
   private static StarPattern starPattern(AstNode starPattern) {
     Token starToken = toPyToken(starPattern.getFirstChild(PythonPunctuator.MUL).getToken());
+    Pattern pattern;
     AstNode capturePattern = starPattern.getFirstChild(PythonGrammar.CAPTURE_PATTERN);
-    return new StarPatternImpl(starToken, new CapturePatternImpl(name(capturePattern.getFirstChild())));
+    if (capturePattern != null) {
+      pattern = new CapturePatternImpl(name(capturePattern.getFirstChild()));
+    } else {
+      pattern = wildcardPattern(starPattern.getFirstChild(PythonGrammar.WILDCARD_PATTERN));
+    }
+    return new StarPatternImpl(starToken, pattern);
   }
 
+  private static WildcardPatternImpl wildcardPattern(AstNode wildcardPattern) {
+    return new WildcardPatternImpl(toPyToken(wildcardPattern.getFirstChild().getToken()));
+  }
+
+
   private static LiteralPattern literalPattern(AstNode literalPattern) {
     LiteralPattern.LiteralKind literalKind;
     if (literalPattern.hasDirectChildren(PythonGrammar.COMPLEX_NUMBER, PythonGrammar.SIGNED_NUMBER)) {

python-frontend/src/main/java/org/sonar/python/tree/StarPatternImpl.java

@@ -21,7 +21,7 @@
 
 import java.util.Arrays;
 import java.util.List;
-import org.sonar.plugins.python.api.tree.CapturePattern;
+import org.sonar.plugins.python.api.tree.Pattern;
 import org.sonar.plugins.python.api.tree.StarPattern;
 import org.sonar.plugins.python.api.tree.Token;
 import org.sonar.plugins.python.api.tree.Tree;
@@ -30,16 +30,16 @@
 public class StarPatternImpl extends PyTree implements StarPattern {
 
   private final Token starToken;
-  private final CapturePattern capturePattern;
+  private final Pattern pattern;
 
-  public StarPatternImpl(Token starToken, CapturePattern capturePattern) {
+  public StarPatternImpl(Token starToken, Pattern pattern) {
     this.starToken = starToken;
-    this.capturePattern = capturePattern;
+    this.pattern = pattern;
   }
 
   @Override
-  public CapturePattern capturePattern() {
-    return capturePattern;
+  public Pattern pattern() {
+    return pattern;
   }
 
   @Override
@@ -54,6 +54,6 @@ public Kind getKind() {
 
   @Override
   List<Tree> computeChildren() {
-    return Arrays.asList(starToken, capturePattern);
+    return Arrays.asList(starToken, pattern);
   }
 }