Support unnamed class compilation unit (#615)

* feat: add UnnamedClassCompilationUnit declaration in parser

* feat: support unnamed class compilation unit (with spec deviation)

* test: add test for Unnamed Class Compilation Unit printing

* chore: update signature

* style: fix prettier issue

packages/java-parser/api.d.ts

@@ -1973,9 +1973,11 @@ export interface TypeDeclarationCstNode extends CstNode {
 }
 
 export type TypeDeclarationCtx = {
+  Semicolon?: IToken[];
   classDeclaration?: ClassDeclarationCstNode[];
   interfaceDeclaration?: InterfaceDeclarationCstNode[];
-  Semicolon?: IToken[];
+  fieldDeclaration?: FieldDeclarationCstNode[];
+  methodDeclaration?: MethodDeclarationCstNode[];
 };
 
 export interface ModuleDeclarationCstNode extends CstNode {

packages/java-parser/src/productions/classes.js

@@ -1,6 +1,7 @@
 "use strict";
 
 const { isRecognitionException, tokenMatcher } = require("chevrotain");
+const { classBodyTypes } = require("./utils/class-body-types");
 
 function defineRules($, t) {
   // https://docs.oracle.com/javase/specs/jls/se16/html/jls-8.html#jls-ClassDeclaration
@@ -110,18 +111,6 @@ function defineRules($, t) {
     $.CONSUME(t.RCurly);
   });
 
-  const classBodyTypes = {
-    unknown: 0,
-    fieldDeclaration: 1,
-    methodDeclaration: 2,
-    classDeclaration: 3,
-    interfaceDeclaration: 4,
-    semiColon: 5,
-    instanceInitializer: 6,
-    staticInitializer: 7,
-    constructorDeclaration: 8
-  };
-
   // https://docs.oracle.com/javase/specs/jls/se16/html/jls-8.html#jls-ClassBodyDeclaration
   $.RULE("classBodyDeclaration", () => {
     const nextRuleType = $.BACKTRACK_LOOKAHEAD(

packages/java-parser/src/productions/packages-and-modules.js

@@ -1,8 +1,16 @@
 "use strict";
 const { isRecognitionException, tokenMatcher, EOF } = require("chevrotain");
+const { classBodyTypes } = require("./utils/class-body-types");
 
 function defineRules($, t) {
-  // https://docs.oracle.com/javase/specs/jls/se16/html/jls-7.html#CompilationUnit
+  /**
+   * Spec Deviation: As OrdinaryCompilationUnit and UnnamedClassCompilationUnit
+   * both can have multiple class or interface declarations, both were combined
+   * in the ordinaryCompilationUnit rule
+   *
+   * https://docs.oracle.com/javase/specs/jls/se21/html/jls-7.html#jls-7.3
+   * https://docs.oracle.com/javase/specs/jls/se21/preview/specs/unnamed-classes-instance-main-methods-jls.html
+   */
   $.RULE("compilationUnit", () => {
     // custom optimized backtracking lookahead logic
     const isModule = $.BACKTRACK_LOOKAHEAD($.isModuleCompilationUnit);
@@ -95,18 +103,40 @@ function defineRules($, t) {
     ]);
   });
 
-  // https://docs.oracle.com/javase/specs/jls/se16/html/jls-7.html#jls-TypeDeclaration
+  /**
+   * Spec Deviation: As OrdinaryCompilationUnit and UnnamedClassCompilationUnit
+   * both can have multiple class or interface declarations, both were combined
+   * in the ordinaryCompilationUnit rule
+   *
+   * As a result, the typeDeclaration combine TopLevelClassOrInterfaceDeclaration and includes fields and method declarations as well
+   * to handle unnamed class compilation unit
+   *
+   * https://docs.oracle.com/javase/specs/jls/se21/html/jls-7.html#jls-TopLevelClassOrInterfaceDeclaration
+   * https://docs.oracle.com/javase/specs/jls/se21/preview/specs/unnamed-classes-instance-main-methods-jls.html
+   */
   $.RULE("typeDeclaration", () => {
     // TODO: consider extracting the prefix modifiers here to avoid backtracking
-    const isClassDeclaration = this.BACKTRACK_LOOKAHEAD($.isClassDeclaration);
+    const nextRuleType = $.BACKTRACK_LOOKAHEAD(
+      $.identifyClassBodyDeclarationType
+    );
 
     $.OR([
+      { ALT: () => $.CONSUME(t.Semicolon) },
       {
-        GATE: () => isClassDeclaration,
+        GATE: () => nextRuleType === classBodyTypes.classDeclaration,
         ALT: () => $.SUBRULE($.classDeclaration)
       },
-      { ALT: () => $.SUBRULE($.interfaceDeclaration) },
-      { ALT: () => $.CONSUME(t.Semicolon) }
+      {
+        GATE: () => nextRuleType === classBodyTypes.interfaceDeclaration,
+        ALT: () => $.SUBRULE($.interfaceDeclaration)
+      },
+      {
+        GATE: () => nextRuleType === classBodyTypes.fieldDeclaration,
+        ALT: () => $.SUBRULE($.fieldDeclaration)
+      },
+      {
+        ALT: () => $.SUBRULE($.methodDeclaration)
+      }
     ]);
   });
 

packages/java-parser/src/productions/utils/class-body-types.js

@@ -0,0 +1,17 @@
+"use strict";
+
+const classBodyTypes = {
+  unknown: 0,
+  fieldDeclaration: 1,
+  methodDeclaration: 2,
+  classDeclaration: 3,
+  interfaceDeclaration: 4,
+  semiColon: 5,
+  instanceInitializer: 6,
+  staticInitializer: 7,
+  constructorDeclaration: 8
+};
+
+module.exports = {
+  classBodyTypes
+};

packages/java-parser/test/compilation-unit/unnamed-class-compilation-unit-spec.js

@@ -0,0 +1,96 @@
+"use strict";
+
+const { expect } = require("chai");
+const javaParser = require("../../src/index");
+
+describe("Unnamed Class Compilation Unit", () => {
+  it("should handle UnnamedClassCompilationUnit", () => {
+    const input = `
+      void main() {
+          System.out.println("Hello, World!");
+      }
+    `;
+    javaParser.parse(input, "compilationUnit");
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with only method", () => {
+    const input = `
+      void main() {
+          System.out.println("Hello, World!");
+      }
+    `;
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with fields", () => {
+    const input = `
+      String greeting = "Hello world!";
+      String hourra = "Hourra!";
+
+      void main() {
+          System.out.println(greeting);
+          System.out.println(hourra);
+      }
+    `;
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with class declaration", () => {
+    const input = `
+      class Test { static String greetings() { return "Hello world!"; } }
+
+      void main() {
+          System.out.println(Test.greetings());
+      }
+    `;
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with interface declaration", () => {
+    const input = `
+      interface Test { default String greetings() { return "Hello world!"; } }
+
+      void main() {
+          System.out.println(Test.greetings());
+      }
+    `;
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with semicolons", () => {
+    const input = `
+      ;
+
+      void main() {
+          System.out.println("Hello World!");
+      }
+    `;
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with class member declarations", () => {
+    const input = `
+      String greeting() { return "Hello, World!"; }
+
+      void main() {
+          System.out.println(greeting());
+      }
+    `;
+
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+
+  it("should handle UnnamedClassCompilationUnit with imports", () => {
+    const input = `
+      import com.toto.titi.Test;
+      import com.toto.titi.Toast;
+
+      void main() {
+          System.out.println(Test.greeting());
+      }
+    `;
+
+    expect(() => javaParser.parse(input, "compilationUnit")).to.not.throw();
+  });
+});

packages/prettier-plugin-java/test/unit-test/unnamed-class-compilation-unit/_input.java

@@ -0,0 +1,12 @@
+import com.toto.titi.Test;
+import com.toto.titi.Toast;
+
+class TestClass { static String greetings() { return "Hello world!"; } }
+interface TestInterface { default String greetings() { return "Hello world!"; } }
+
+;
+String greeting() { return "Hello, World!"; }
+
+void main() {
+  System.out.println(Test.greeting());
+}

packages/prettier-plugin-java/test/unit-test/unnamed-class-compilation-unit/_output.java

@@ -0,0 +1,23 @@
+import com.toto.titi.Test;
+import com.toto.titi.Toast;
+
+class TestClass {
+
+  static String greetings() {
+    return "Hello world!";
+  }
+}
+
+interface TestInterface {
+  default String greetings() {
+    return "Hello world!";
+  }
+}
+
+String greeting() {
+  return "Hello, World!";
+}
+
+void main() {
+  System.out.println(Test.greeting());
+}

packages/prettier-plugin-java/test/unit-test/unnamed-class-compilation-unit/unnamed-class-compilation-unit-spec.ts

@@ -0,0 +1,5 @@
+import { testSample } from "../../test-utils";
+
+describe("prettier-java: Unnamed Class Compilation Unit", () => {
+  testSample(__dirname);
+});