SONARPY-908 Basic support of match / case statement (#969)

Author: andrea-guarino-sonarsource

python-checks/src/test/resources/checks/stringLiteralDuplication.py

@@ -103,3 +103,16 @@ def type_hints_should_be_excluded():
     a: "httpx.Response"
     b: "httpx.Response"
     c: "httpx.Response"
+
+def literal_patterns_should_be_excluded(value1, value2, value3):
+    match value1:
+        case "This is a duplicated pattern":
+            print("This is a duplicated literal")  # Noncompliant
+
+    match value2:
+        case "This is a duplicated pattern":
+            print("This is a duplicated literal")
+
+    match value3:
+        case "This is a duplicated pattern":
+            print("This is a duplicated literal")

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

@@ -471,4 +471,27 @@ public void visitFormattedExpression(FormattedExpression formattedExpression) {
   public void visitFormatSpecifier(FormatSpecifier formatSpecifier) {
     scan(formatSpecifier.formatExpressions());
   }
+
+  @Override
+  public void visitMatchStatement(MatchStatement matchStatement) {
+    scan(matchStatement.subjectExpression());
+    scan(matchStatement.caseBlocks());
+  }
+
+  @Override
+  public void visitCaseBlock(CaseBlock caseBlock) {
+    scan(caseBlock.patterns());
+    scan(caseBlock.guard());
+    scan(caseBlock.body());
+  }
+
+  @Override
+  public void visitLiteralPattern(LiteralPattern literalPattern) {
+    // noop
+  }
+
+  @Override
+  public void visitGuard(Guard guard) {
+    scan(guard.condition());
+  }
 }

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

@@ -0,0 +1,47 @@
+/*
+ * 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;
+
+
+import java.util.List;
+import javax.annotation.CheckForNull;
+
+/**
+ * Case block
+ *
+ * <pre>
+ *   {@link #caseKeyword()} {@link #patterns()} {@link #guard()}:
+ *     {@link #body()}
+ * </pre>
+ *
+ * See https://docs.python.org/3/reference/compound_stmts.html#grammar-token-python-grammar-case_block
+ */
+public interface CaseBlock extends Tree {
+
+  Token caseKeyword();
+
+  List<Pattern> patterns();
+
+  @CheckForNull
+  Guard guard();
+
+  StatementList body();
+
+}

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

@@ -0,0 +1,35 @@
+/*
+ * 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;
+
+/**
+ * Guard
+ *
+ * <pre> {@link #ifKeyword()} {@link #condition()}</pre>
+ *
+ * See https://docs.python.org/3/reference/compound_stmts.html#guards
+ */
+public interface Guard extends Tree {
+
+  Token ifKeyword();
+
+  Expression condition();
+
+}

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

@@ -0,0 +1,50 @@
+/*
+ * 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;
+
+/**
+ * Literal Pattern
+ *
+ * <pre>
+ *   case "foo":
+ *     ...
+ *   case 42:
+ *     ...
+ *   case True:
+ *     ...
+ *   case None:
+ *     ...
+ * </pre>
+ *
+ * See https://docs.python.org/3/reference/compound_stmts.html#literal-patterns
+ */
+public interface LiteralPattern extends Pattern {
+
+  String valueAsString();
+
+  LiteralKind literalKind();
+
+  enum LiteralKind {
+    STRING,
+    NUMBER,
+    BOOLEAN,
+    NONE
+  }
+}

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

@@ -0,0 +1,42 @@
+/*
+ * 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;
+
+
+import java.util.List;
+
+/**
+ * Match statement
+ *
+ * <pre>
+ *   {@link #matchKeyword()} {@link #subjectExpression()} :
+ *     {@link #caseBlocks()}
+ * </pre>
+ *
+ * See https://docs.python.org/3/reference/compound_stmts.html#the-match-statement
+ */
+public interface MatchStatement extends Statement {
+
+  Token matchKeyword();
+
+  Expression subjectExpression();
+
+  List<CaseBlock> caseBlocks();
+}

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

@@ -0,0 +1,24 @@
+/*
+ * 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 Pattern extends Tree {
+
+}

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

@@ -56,6 +56,8 @@ enum Kind {
 
     CALL_EXPR(CallExpression.class),
 
+    CASE_BLOCK(CaseBlock.class),
+
     CLASSDEF(ClassDef.class),
 
     CONDITIONAL_EXPR(ConditionalExpression.class),
@@ -94,6 +96,8 @@ enum Kind {
 
     GLOBAL_STMT(GlobalStatement.class),
 
+    GUARD(Guard.class),
+
     IF_STMT(IfStatement.class),
 
     IMPORT_FROM(ImportFrom.class),
@@ -106,6 +110,10 @@ enum Kind {
 
     LIST_LITERAL(ListLiteral.class),
 
+    LITERAL_PATTERN(LiteralPattern.class),
+
+    MATCH_STMT(MatchStatement.class),
+
     NAME(Name.class),
 
     NONLOCAL_STMT(NonlocalStatement.class),

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

@@ -172,4 +172,12 @@ public interface TreeVisitor {
   void visitFormattedExpression(FormattedExpression formattedExpression);
 
   void visitFormatSpecifier(FormatSpecifier formatSpecifier);
+
+  void visitMatchStatement(MatchStatement matchStatement);
+
+  void visitCaseBlock(CaseBlock caseBlock);
+
+  void visitLiteralPattern(LiteralPattern literalPattern);
+
+  void visitGuard(Guard guard);
 }

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

@@ -29,6 +29,7 @@
 import static org.sonar.python.api.PythonTokenType.DEDENT;
 import static org.sonar.python.api.PythonTokenType.INDENT;
 import static org.sonar.python.api.PythonTokenType.NEWLINE;
+import static org.sonar.python.api.PythonTokenType.NUMBER;
 
 public enum PythonGrammar implements GrammarRuleKey {
   FACTOR,
@@ -83,6 +84,8 @@ public enum PythonGrammar implements GrammarRuleKey {
   OR_EXPR,
 
   NAMED_EXPR_TEST,
+  STAR_NAMED_EXPRESSIONS,
+  STAR_NAMED_EXPRESSION,
   FORMATTED_EXPR,
   F_STRING_CONTENT,
   FORMAT_SPECIFIER,
@@ -146,6 +149,17 @@ public enum PythonGrammar implements GrammarRuleKey {
   WITH_STMT,
   WITH_ITEM,
 
+  MATCH_STMT,
+  SUBJECT_EXPR,
+  CASE_BLOCK,
+  GUARD,
+
+  PATTERNS,
+  LITERAL_PATTERN,
+
+  SIGNED_NUMBER,
+  COMPLEX_NUMBER,
+
   FUNCDEF,
   DECORATORS,
   DECORATOR,
@@ -193,6 +207,11 @@ public static void grammar(LexerfulGrammarBuilder b) {
     b.rule(AUGASSIGN).is(b.firstOf("+=", "-=", "*=", "/=", "//=", "%=", "**=", ">>=", "<<=", "&=", "^=", "|=", "@="));
 
     b.rule(NAMED_EXPR_TEST).is(TEST, b.optional(PythonPunctuator.WALRUS_OPERATOR, TEST));
+    b.rule(STAR_NAMED_EXPRESSIONS).is(STAR_NAMED_EXPRESSION, b.zeroOrMore(",", STAR_NAMED_EXPRESSION), b.optional(","));
+    b.rule(STAR_NAMED_EXPRESSION).is(b.firstOf(
+      STAR_EXPR,
+      NAMED_EXPR_TEST
+    ));
     b.rule(TEST).is(b.firstOf(
       b.sequence(OR_TEST, b.optional("if", OR_TEST, "else", TEST)),
       LAMBDEF));
@@ -401,6 +420,7 @@ public static void compoundStatements(LexerfulGrammarBuilder b) {
       FOR_STMT,
       TRY_STMT,
       WITH_STMT,
+      MATCH_STMT,
       FUNCDEF,
       CLASSDEF,
       ASYNC_STMT));
@@ -430,6 +450,33 @@ public static void compoundStatements(LexerfulGrammarBuilder b) {
     ));
     b.rule(WITH_ITEM).is(TEST, b.optional("as", EXPR));
 
+    b.rule(MATCH_STMT).is("match", SUBJECT_EXPR, ":", NEWLINE, INDENT, b.oneOrMore(CASE_BLOCK), DEDENT);
+    b.rule(SUBJECT_EXPR).is(STAR_NAMED_EXPRESSIONS);
+    b.rule(CASE_BLOCK).is("case", PATTERNS, b.optional(GUARD), ":", SUITE);
+    b.rule(GUARD).is("if", NAMED_EXPR_TEST);
+
+    // TODO: this should be either OR_PATTERN or AS_PATTERN
+    b.rule(PATTERNS).is(LITERAL_PATTERN);
+
+    b.rule(LITERAL_PATTERN).is(b.firstOf(
+      COMPLEX_NUMBER,
+      SIGNED_NUMBER,
+      b.oneOrMore(PythonTokenType.STRING),
+      PythonKeyword.NONE,
+      "True",
+      "False"
+    ));
+
+    b.rule(COMPLEX_NUMBER).is(b.firstOf(
+      b.sequence(SIGNED_NUMBER, "+" , NUMBER),
+      b.sequence(SIGNED_NUMBER, "-", NUMBER))
+    );
+
+    b.rule(SIGNED_NUMBER).is(b.firstOf(
+      NUMBER,
+      b.sequence("-", NUMBER)
+    ));
+
     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);