SONARPY-918 Add capture pattern

Author: andreaguarino

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

@@ -500,4 +500,9 @@ public void visitAsPattern(AsPattern asPattern) {
   public void visitGuard(Guard guard) {
     scan(guard.condition());
   }
+
+  @Override
+  public void visitCapturePattern(CapturePattern capturePattern) {
+    scan(capturePattern.name());
+  }
 }

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

@@ -0,0 +1,25 @@
+/*
+ * 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;
+
+public interface CapturePattern extends Pattern {
+
+  Name name();
+}

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

@@ -58,6 +58,8 @@ enum Kind {
 
     CALL_EXPR(CallExpression.class),
 
+    CAPTURE_PATTERN(CapturePattern.class),
+
     CASE_BLOCK(CaseBlock.class),
 
     CLASSDEF(ClassDef.class),

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

@@ -182,4 +182,6 @@ public interface TreeVisitor {
   void visitAsPattern(AsPattern asPattern);
 
   void visitGuard(Guard guard);
+
+  void visitCapturePattern(CapturePattern capturePattern);
 }

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

@@ -459,7 +459,7 @@ public static void compoundStatements(LexerfulGrammarBuilder b) {
     b.rule(GUARD).is("if", NAMED_EXPR_TEST);
 
     b.rule(PATTERN).is(b.firstOf(AS_PATTERN, CLOSED_PATTERN));
-    b.rule(CLOSED_PATTERN).is(LITERAL_PATTERN);
+    b.rule(CLOSED_PATTERN).is(b.firstOf(LITERAL_PATTERN, CAPTURE_PATTERN));
     b.rule(AS_PATTERN).is(CLOSED_PATTERN, "as", CAPTURE_PATTERN);
     b.rule(CAPTURE_PATTERN).is(NAME);
 

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

@@ -0,0 +1,56 @@
+/*
+ * 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.Collections;
+import java.util.List;
+import org.sonar.plugins.python.api.tree.CapturePattern;
+import org.sonar.plugins.python.api.tree.Name;
+import org.sonar.plugins.python.api.tree.Tree;
+import org.sonar.plugins.python.api.tree.TreeVisitor;
+
+public class CapturePatternImpl extends PyTree implements CapturePattern {
+
+  private final Name name;
+
+  public CapturePatternImpl(Name name) {
+    this.name = name;
+  }
+
+  @Override
+  public Name name() {
+    return name;
+  }
+
+  @Override
+  public void accept(TreeVisitor visitor) {
+    visitor.visitCapturePattern(this);
+  }
+
+  @Override
+  public Kind getKind() {
+    return Kind.CAPTURE_PATTERN;
+  }
+
+  @Override
+  List<Tree> computeChildren() {
+    return Collections.singletonList(name);
+  }
+}

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

@@ -823,14 +823,11 @@ public Guard guard(AstNode guardNode) {
     return new GuardImpl(ifKeyword, condition);
   }
 
-  private static Pattern pattern(AstNode pattern) {
-    // TODO: consider OR Patterns and other kind of patterns
+  public static Pattern pattern(AstNode pattern) {
     if (pattern.is(PythonGrammar.CLOSED_PATTERN)) {
-      return literalPattern(pattern.getFirstChild());
-    } else if (pattern.is(PythonGrammar.AS_PATTERN)) {
-      return asPattern(pattern);
+      return closedPattern(pattern);
     }
-    throw new IllegalStateException(String.format("Pattern %s not recognized.", pattern.getName()));
+    return asPattern(pattern);
   }
 
   private static AsPattern asPattern(AstNode asPattern) {
@@ -840,6 +837,16 @@ private static AsPattern asPattern(AstNode asPattern) {
     return new AsPatternImpl(pattern, asKeyword, alias);
   }
 
+  private static Pattern closedPattern(AstNode closedPattern) {
+    AstNode astNode = closedPattern.getFirstChild();
+    if (astNode.is(PythonGrammar.LITERAL_PATTERN)) {
+      return literalPattern(astNode);
+    } else if (astNode.is(PythonGrammar.CAPTURE_PATTERN)) {
+      return new CapturePatternImpl(name(astNode.getFirstChild()));
+    }
+    throw new IllegalStateException(String.format("Pattern %s not recognized.", closedPattern.getName()));
+  }
+
   private static LiteralPattern literalPattern(AstNode literalPattern) {
     LiteralPattern.LiteralKind literalKind;
     if (literalPattern.hasDirectChildren(PythonGrammar.COMPLEX_NUMBER, PythonGrammar.SIGNED_NUMBER)) {

python-frontend/src/test/java/org/sonar/plugins/python/api/tree/BaseTreeVisitorTest.java

@@ -400,4 +400,25 @@ public void guard() {
 
     verify(visitor).visitBinaryExpression(((BinaryExpression) guard.condition()));
   }
+
+  @Test
+  public void as_pattern() {
+    setRootRule(PythonGrammar.AS_PATTERN);
+    AsPattern pattern = ((AsPattern) parse("'foo' as x", PythonTreeMaker::pattern));
+    FirstLastTokenVerifierVisitor visitor = spy(FirstLastTokenVerifierVisitor.class);
+    pattern.accept(visitor);
+
+    verify(visitor).visitLiteralPattern((LiteralPattern) pattern.pattern());
+    verify(visitor).visitName(pattern.alias());
+  }
+
+  @Test
+  public void capture_pattern() {
+    setRootRule(PythonGrammar.CLOSED_PATTERN);
+    CapturePattern pattern = ((CapturePattern) parse("x", PythonTreeMaker::pattern));
+    FirstLastTokenVerifierVisitor visitor = spy(FirstLastTokenVerifierVisitor.class);
+    pattern.accept(visitor);
+
+    verify(visitor).visitName(pattern.name());
+  }
 }

python-frontend/src/test/java/org/sonar/python/parser/compound/statements/CasePatternsTest.java

@@ -47,6 +47,7 @@ public void none() {
 
   @Test
   public void booleans() {
+    setRootRule(PythonGrammar.LITERAL_PATTERN);
     assertThat(p)
       .matches("True")
       .matches("False")
@@ -71,6 +72,13 @@ public void complex_numbers() {
   public void as_patterns() {
     assertThat(p)
       .matches("'foo' as x")
+      .matches("x as y")
       .notMatches("'foo' as x as y");
   }
+
+  @Test
+  public void capture() {
+    assertThat(p)
+      .matches("x");
+  }
 }

python-frontend/src/test/java/org/sonar/python/tree/PythonTreeMakerMatchStatementTest.java

@@ -21,6 +21,7 @@
 
 import org.junit.Test;
 import org.sonar.plugins.python.api.tree.AsPattern;
+import org.sonar.plugins.python.api.tree.CapturePattern;
 import org.sonar.plugins.python.api.tree.CaseBlock;
 import org.sonar.plugins.python.api.tree.Expression;
 import org.sonar.plugins.python.api.tree.Guard;
@@ -157,4 +158,13 @@ public void as_pattern() {
     assertThat(asPattern.alias().name()).isEqualTo("x");
     assertThat(asPattern.children()).extracting(Tree::getKind).containsExactly(Tree.Kind.LITERAL_PATTERN, Tree.Kind.TOKEN, Tree.Kind.NAME);
   }
+
+  @Test
+  public void capture_pattern() {
+    setRootRule(PythonGrammar.CASE_BLOCK);
+    CaseBlock caseBlock = parse("case x: ...", treeMaker::caseBlock);
+    CapturePattern capturePattern = (CapturePattern) caseBlock.pattern();
+    assertThat(capturePattern.name().name()).isEqualTo("x");
+    assertThat(capturePattern.children()).containsExactly(capturePattern.name());
+  }
 }