DevirtualizePrototypeMethodsTest.java

/*
 * Copyright 2009 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.javascript.jscomp;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import com.google.javascript.rhino.jstype.JSType;
import java.util.ArrayList;
import java.util.List;

/**
 * Tests for {@link DevirtualizePrototypeMethods}
 *
 */
public final class DevirtualizePrototypeMethodsTest extends CompilerTestCase {
  private static final String EXTERNAL_SYMBOLS =
      "var extern;extern.externalMethod";
  private final List<String> typeInformation;

  public DevirtualizePrototypeMethodsTest() {
    super(EXTERNAL_SYMBOLS);
    typeInformation = new ArrayList<>();
  }

  @Override
  protected int getNumRepetitions() {
    // run pass once.
    return 1;
  }

  @Override
  protected void setUp() throws Exception {
    super.setUp();
    disableTypeCheck();
  }

  /**
   * Combine source strings using ';' as the separator.
   */
  private static String semicolonJoin(String ... parts) {
    return Joiner.on(";").join(parts);
  }

  /**
   * Inputs for prototype method tests.
   */
  private static class RewritePrototypeMethodTestInput {
    static final String INPUT =
        LINE_JOINER.join(
            "/** @constructor */",
            "function a() { this.x = 3; }",
            "/** @return {number} */",
            "a.prototype.foo = function() { return this.x; };",
            "/** @param {number} p\n@return {number} */",
            "a.prototype.bar = function(p) { return this.x; };",
            "a.prototype.baz = function() {};",
            "var o = new a;",
            "o.foo();",
            "o.bar(2);",
            "o.baz()");

    static final String EXPECTED =
        LINE_JOINER.join(
            "/** @constructor */",
            "function a(){ this.x = 3; }",
            "var JSCompiler_StaticMethods_foo = ",
            "function(JSCompiler_StaticMethods_foo$self) {",
            "  return JSCompiler_StaticMethods_foo$self.x",
            "};",
            "var JSCompiler_StaticMethods_bar = ",
            "function(JSCompiler_StaticMethods_bar$self, p) {",
            "  return JSCompiler_StaticMethods_bar$self.x",
            "};",
            "var JSCompiler_StaticMethods_baz = ",
            "function(JSCompiler_StaticMethods_baz$self) {",
            "};",
            "var o = new a;",
            "JSCompiler_StaticMethods_foo(o);",
            "JSCompiler_StaticMethods_bar(o, 2);",
            "JSCompiler_StaticMethods_baz(o)");

    static final ImmutableList<String> EXPECTED_TYPE_CHECKING_OFF =
        ImmutableList.of(
            "FUNCTION a = null",
            "NAME JSCompiler_StaticMethods_foo$self = null",
            "FUNCTION JSCompiler_StaticMethods_foo = null",
            "NAME JSCompiler_StaticMethods_bar$self = null",
            "FUNCTION JSCompiler_StaticMethods_bar = null",
            "FUNCTION JSCompiler_StaticMethods_baz = null",
            "NEW a = null",
            "CALL JSCompiler_StaticMethods_foo = null",
            "CALL JSCompiler_StaticMethods_bar = null",
            "CALL JSCompiler_StaticMethods_baz = null");

    static final ImmutableList<String> EXPECTED_TYPE_CHECKING_ON =
        ImmutableList.of(
            "FUNCTION a = function (new:a): undefined",
            "NAME JSCompiler_StaticMethods_foo$self = a",
            "FUNCTION JSCompiler_StaticMethods_foo = function (a): number",
            "NAME JSCompiler_StaticMethods_bar$self = a",
            "FUNCTION JSCompiler_StaticMethods_bar = function (a, number): number",
            "FUNCTION JSCompiler_StaticMethods_baz = function (a): undefined",
            "NEW a = a",
            "CALL JSCompiler_StaticMethods_foo = number",
            "CALL JSCompiler_StaticMethods_bar = number",
            "CALL JSCompiler_StaticMethods_baz = undefined");

    private RewritePrototypeMethodTestInput() {}
  }

  public void testRewritePrototypeMethods1() throws Exception {
    // type checking off
    disableTypeCheck();
    checkTypes(RewritePrototypeMethodTestInput.INPUT,
               RewritePrototypeMethodTestInput.EXPECTED,
               RewritePrototypeMethodTestInput.EXPECTED_TYPE_CHECKING_OFF);
  }

  public void testRewritePrototypeMethods2() throws Exception {
    // type checking on
    enableTypeCheck();
    checkTypes(RewritePrototypeMethodTestInput.INPUT,
               RewritePrototypeMethodTestInput.EXPECTED,
               RewritePrototypeMethodTestInput.EXPECTED_TYPE_CHECKING_ON);
  }

  public void testRewriteChained() throws Exception {
    String source =
        LINE_JOINER.join(
            "A.prototype.foo = function(){return this.b};",
            "B.prototype.bar = function(){};",
            "o.foo().bar()");

    String expected =
        LINE_JOINER.join(
            "var JSCompiler_StaticMethods_foo = ",
            "function(JSCompiler_StaticMethods_foo$self) {",
            "  return JSCompiler_StaticMethods_foo$self.b",
            "};",
            "var JSCompiler_StaticMethods_bar = ",
            "function(JSCompiler_StaticMethods_bar$self) {",
            "};",
            "JSCompiler_StaticMethods_bar(JSCompiler_StaticMethods_foo(o))");
    test(source, expected);
  }

  /**
   * Inputs for declaration used as an r-value tests.
   */
  private static class NoRewriteDeclarationUsedAsRValue {
    static final String DECL = "a.prototype.foo = function() {}";
    static final String CALL = "o.foo()";

    private NoRewriteDeclarationUsedAsRValue() {}
  }

  public void testRewriteDeclIsExpressionStatement() throws Exception {
    test(semicolonJoin(NoRewriteDeclarationUsedAsRValue.DECL,
                       NoRewriteDeclarationUsedAsRValue.CALL),
         "var JSCompiler_StaticMethods_foo =" +
         "function(JSCompiler_StaticMethods_foo$self) {};" +
         "JSCompiler_StaticMethods_foo(o)");
  }

  public void testNoRewriteDeclUsedAsAssignmentRhs() throws Exception {
    testSame(semicolonJoin("var c = " + NoRewriteDeclarationUsedAsRValue.DECL,
                           NoRewriteDeclarationUsedAsRValue.CALL));
  }

  public void testNoRewriteDeclUsedAsCallArgument() throws Exception {
    testSame(semicolonJoin("f(" + NoRewriteDeclarationUsedAsRValue.DECL + ")",
                           NoRewriteDeclarationUsedAsRValue.CALL));
  }

  /**
   * Inputs for restrict-to-global-scope tests.
   */
  private static class NoRewriteIfNotInGlobalScopeTestInput {
    static final String INPUT =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype.foo = function() {return this.x};",
            "var o = new a;",
            "o.foo()");

    private NoRewriteIfNotInGlobalScopeTestInput() {}
  }

  public void testRewriteInGlobalScope() throws Exception {
    String expected =
        LINE_JOINER.join(
            "function a(){}",
            "var JSCompiler_StaticMethods_foo = ",
            "function(JSCompiler_StaticMethods_foo$self) {",
            "  return JSCompiler_StaticMethods_foo$self.x",
            "};",
            "var o = new a;",
            "JSCompiler_StaticMethods_foo(o);");

    test(NoRewriteIfNotInGlobalScopeTestInput.INPUT, expected);
  }

  public void testNoRewriteIfNotInGlobalScope1() throws Exception {
    setAcceptedLanguage(CompilerOptions.LanguageMode.ECMASCRIPT_2015);
    testSame("if(true){" + NoRewriteIfNotInGlobalScopeTestInput.INPUT + "}");
  }

  public void testNoRewriteIfNotInGlobalScope2() throws Exception {
    testSame("function enclosingFunction() {" +
             NoRewriteIfNotInGlobalScopeTestInput.INPUT +
             "}");
  }

  public void testNoRewriteNamespaceFunctions() throws Exception {
    String source = "function a(){}; a.foo = function() {return this.x}; a.foo()";
    testSame(source);
  }

  public void testRewriteIfDuplicates() throws Exception {
    test(
        LINE_JOINER.join(
            "function A(){}; A.prototype.getFoo = function() { return 1; }; ",
            "function B(){}; B.prototype.getFoo = function() { return 1; }; ",
            "var x = Math.random() ? new A() : new B();",
            "alert(x.getFoo());"),
        LINE_JOINER.join(
            "function A(){}; ",
            "var JSCompiler_StaticMethods_getFoo=",
            "function(JSCompiler_StaticMethods_getFoo$self){return 1};",
            "function B(){};",
            "B.prototype.getFoo=function(){return 1};",
            "var x = Math.random() ? new A() : new B();",
            "alert(JSCompiler_StaticMethods_getFoo(x));"));
  }

  public void testRewriteIfDuplicatesWithThis() throws Exception {
    test(
        LINE_JOINER.join(
            "function A(){}; A.prototype.getFoo = ",
            "function() { return this._foo + 1; }; ",
            "function B(){}; B.prototype.getFoo = ",
            "function() { return this._foo + 1; }; ",
            "var x = Math.random() ? new A() : new B();",
            "alert(x.getFoo());"),
        LINE_JOINER.join(
            "function A(){}; ",
            "var JSCompiler_StaticMethods_getFoo=",
            "function(JSCompiler_StaticMethods_getFoo$self){",
            "  return JSCompiler_StaticMethods_getFoo$self._foo + 1",
            "};",
            "function B(){};",
            "B.prototype.getFoo=function(){return this._foo + 1};",
            "var x = Math.random() ? new A() : new B();",
            "alert(JSCompiler_StaticMethods_getFoo(x));"));
  }

  public void testNoRewriteIfDuplicates() throws Exception {
    testSame(
        LINE_JOINER.join(
            "function A(){}; A.prototype.getFoo = function() { return 1; }; ",
            "function B(){}; B.prototype.getFoo = function() { return 2; }; ",
            "var x = Math.random() ? new A() : new B();",
            "alert(x.getFoo());"));
  }

  /**
   * Inputs for object literal tests.
   */
  private static class NoRewritePrototypeObjectLiteralsTestInput {
    static final String REGULAR = "b.prototype.foo = function() { return 1; }";
    static final String OBJ_LIT = "a.prototype = {foo : function() { return 2; }}";
    static final String CALL = "o.foo()";

    private NoRewritePrototypeObjectLiteralsTestInput() {}
  }

  public void testRewritePrototypeNoObjectLiterals() throws Exception {
    test(
        semicolonJoin(
            NoRewritePrototypeObjectLiteralsTestInput.REGULAR,
            NoRewritePrototypeObjectLiteralsTestInput.CALL),
        LINE_JOINER.join(
            "var JSCompiler_StaticMethods_foo = ",
            "function(JSCompiler_StaticMethods_foo$self) { return 1; };",
            "JSCompiler_StaticMethods_foo(o)"));
  }

  public void testRewritePrototypeObjectLiterals1() throws Exception {
    test(
        semicolonJoin(
            NoRewritePrototypeObjectLiteralsTestInput.OBJ_LIT,
            NoRewritePrototypeObjectLiteralsTestInput.CALL),
        LINE_JOINER.join(
            "a.prototype={};",
            "var JSCompiler_StaticMethods_foo=",
            "function(JSCompiler_StaticMethods_foo$self){ return 2; };",
            "JSCompiler_StaticMethods_foo(o)"));
  }

  public void testNoRewritePrototypeObjectLiterals2() throws Exception {
    testSame(semicolonJoin(NoRewritePrototypeObjectLiteralsTestInput.OBJ_LIT,
                           NoRewritePrototypeObjectLiteralsTestInput.REGULAR,
                           NoRewritePrototypeObjectLiteralsTestInput.CALL));
  }

  public void testNoRewriteExternalMethods1() throws Exception {
    testSame("a.externalMethod()");
  }

  public void testNoRewriteExternalMethods2() throws Exception {
    testSame("A.prototype.externalMethod = function(){}; o.externalMethod()");
  }

  public void testNoRewriteCodingConvention() throws Exception {
    // no rename, leading _ indicates exported symbol
    testSame("a.prototype._foo = function() {};");
  }

  public void testRewriteNoVarArgs() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype.foo = function(args) {return args};",
            "var o = new a;",
            "o.foo()");

    String expected =
        LINE_JOINER.join(
            "function a(){}",
            "var JSCompiler_StaticMethods_foo = ",
            "  function(JSCompiler_StaticMethods_foo$self, args) {return args};",
            "var o = new a;",
            "JSCompiler_StaticMethods_foo(o)");

    test(source, expected);
  }

  public void testNoRewriteVarArgs() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype.foo = function(var_args) {return arguments};",
            "var o = new a;",
            "o.foo()");
    testSame(source);
  }

  /**
   * Inputs for invalidating reference tests.
   */
  private static class NoRewriteNonCallReferenceTestInput {
    static final String BASE =
        "function a(){}\na.prototype.foo = function() {return this.x};\nvar o = new a;";

    private NoRewriteNonCallReferenceTestInput() {}
  }

  public void testRewriteCallReference() throws Exception {
    String expected =
        LINE_JOINER.join(
            "function a(){}",
            "var JSCompiler_StaticMethods_foo = ",
            "function(JSCompiler_StaticMethods_foo$self) {",
            "  return JSCompiler_StaticMethods_foo$self.x",
            "};",
            "var o = new a;",
            "JSCompiler_StaticMethods_foo(o);");

    test(NoRewriteNonCallReferenceTestInput.BASE + "o.foo()", expected);
  }

  public void testNoRewriteNoReferences() throws Exception {
    testSame(NoRewriteNonCallReferenceTestInput.BASE);
  }

  public void testNoRewriteNonCallReference() throws Exception {
    testSame(NoRewriteNonCallReferenceTestInput.BASE + "o.foo && o.foo()");
  }

  /**
   * Inputs for nested definition tests.
   */
  private static class NoRewriteNestedFunctionTestInput {
    static final String PREFIX = "a.prototype.foo = function() {";
    static final String SUFFIX = "o.foo()";
    static final String INNER = "a.prototype.bar = function() {}; o.bar()";
    static final String EXPECTED_PREFIX =
        "var JSCompiler_StaticMethods_foo=" +
        "function(JSCompiler_StaticMethods_foo$self){";
    static final String EXPECTED_SUFFIX =
        "JSCompiler_StaticMethods_foo(o)";

    private NoRewriteNestedFunctionTestInput() {}
  }

  public void testRewriteNoNestedFunction() throws Exception {
    test(semicolonJoin(
             NoRewriteNestedFunctionTestInput.PREFIX + "}",
             NoRewriteNestedFunctionTestInput.SUFFIX,
             NoRewriteNestedFunctionTestInput.INNER),
         semicolonJoin(
             NoRewriteNestedFunctionTestInput.EXPECTED_PREFIX + "}",
             NoRewriteNestedFunctionTestInput.EXPECTED_SUFFIX,
             "var JSCompiler_StaticMethods_bar=" +
             "function(JSCompiler_StaticMethods_bar$self){}",
             "JSCompiler_StaticMethods_bar(o)"));
  }

  public void testNoRewriteNestedFunction() throws Exception {
    test(NoRewriteNestedFunctionTestInput.PREFIX +
         NoRewriteNestedFunctionTestInput.INNER + "};" +
         NoRewriteNestedFunctionTestInput.SUFFIX,
         NoRewriteNestedFunctionTestInput.EXPECTED_PREFIX +
         NoRewriteNestedFunctionTestInput.INNER + "};" +
         NoRewriteNestedFunctionTestInput.EXPECTED_SUFFIX);
  }

  public void testRewriteImplementedMethod() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype.foo = function(args) {return args};",
            "var o = new a;",
            "o.foo()");
    String expected =
        LINE_JOINER.join(
            "function a(){}",
            "var JSCompiler_StaticMethods_foo = ",
            "  function(JSCompiler_StaticMethods_foo$self, args) {return args};",
            "var o = new a;",
            "JSCompiler_StaticMethods_foo(o)");
    test(source, expected);
  }

  public void testRewriteImplementedMethod2() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype['foo'] = function(args) {return args};",
            "var o = new a;",
            "o.foo()");
    testSame(source);
  }

  public void testRewriteImplementedMethod3() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype.foo = function(args) {return args};",
            "var o = new a;",
            "o['foo']");
    testSame(source);
  }

  public void testRewriteImplementedMethod4() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype['foo'] = function(args) {return args};",
            "var o = new a;",
            "o['foo']");
    testSame(source);
  }

  public void testRewriteImplementedMethod5() throws Exception {
    String source = "(function() {this.foo()}).prototype.foo = function() {extern();};";
    testSame(source);
  }

  public void testRewriteImplementedMethodInObj() throws Exception {
    String source =
        LINE_JOINER.join(
            "function a(){}",
            "a.prototype = {foo: function(args) {return args}};",
            "var o = new a;",
            "o.foo()");
    test(source,
        "function a(){}" +
        "a.prototype={};" +
        "var JSCompiler_StaticMethods_foo=" +
        "function(JSCompiler_StaticMethods_foo$self,args){return args};" +
        "var o=new a;" +
        "JSCompiler_StaticMethods_foo(o)");
  }

  public void testNoRewriteGet1() throws Exception {
    // Getters and setter require special handling.
    testSame("function a(){}; a.prototype = {get foo(){return f}}; var o = new a; o.foo()");
  }

  public void testNoRewriteGet2() throws Exception {
    // Getters and setter require special handling.
    testSame("function a(){}; a.prototype = {get foo(){return 1}}; var o = new a; o.foo");
  }

  public void testNoRewriteSet1() throws Exception {
    // Getters and setter require special handling.
    String source = "function a(){}; a.prototype = {set foo(a){}}; var o = new a; o.foo()";
    testSame(source);
  }

  public void testNoRewriteSet2() throws Exception {
    // Getters and setter require special handling.
    String source = "function a(){}; a.prototype = {set foo(a){}}; var o = new a; o.foo = 1";
    testSame(source);
  }

  public void testNoRewriteNotImplementedMethod() throws Exception {
    testSame("function a(){}; var o = new a; o.foo()");
  }

  public void testWrapper() {
    testSame("(function() {})()");
  }

  private static class ModuleTestInput {
    static final String DEFINITION = "a.prototype.foo = function() {}";
    static final String USE = "x.foo()";

    static final String REWRITTEN_DEFINITION =
        "var JSCompiler_StaticMethods_foo=" +
        "function(JSCompiler_StaticMethods_foo$self){}";
    static final String REWRITTEN_USE =
        "JSCompiler_StaticMethods_foo(x)";

    private ModuleTestInput() {}
  }

  public void testRewriteSameModule1() throws Exception {
    JSModule[] modules = createModuleStar(
        // m1
        semicolonJoin(ModuleTestInput.DEFINITION,
                      ModuleTestInput.USE),
        // m2
        "");

    test(modules, new String[] {
        // m1
        semicolonJoin(ModuleTestInput.REWRITTEN_DEFINITION,
                      ModuleTestInput.REWRITTEN_USE),
        // m2
        "",
      });
  }

  public void testRewriteSameModule2() throws Exception {
    JSModule[] modules = createModuleStar(
        // m1
        "",
        // m2
        semicolonJoin(ModuleTestInput.DEFINITION,
                      ModuleTestInput.USE));

    test(modules, new String[] {
        // m1
        "",
        // m2
        semicolonJoin(ModuleTestInput.REWRITTEN_DEFINITION,
                      ModuleTestInput.REWRITTEN_USE)
      });
  }

  public void testRewriteSameModule3() throws Exception {
    JSModule[] modules = createModuleStar(
        // m1
        semicolonJoin(ModuleTestInput.USE,
                      ModuleTestInput.DEFINITION),
        // m2
        "");

    test(modules, new String[] {
        // m1
        semicolonJoin(ModuleTestInput.REWRITTEN_USE,
                      ModuleTestInput.REWRITTEN_DEFINITION),
        // m2
        ""
      });
  }

  public void testRewriteDefinitionBeforeUse() throws Exception {
    JSModule[] modules = createModuleStar(
        // m1
        ModuleTestInput.DEFINITION,
        // m2
        ModuleTestInput.USE);

    test(modules, new String[] {
        // m1
        ModuleTestInput.REWRITTEN_DEFINITION,
        // m2
        ModuleTestInput.REWRITTEN_USE
      });
  }

  public void testNoRewriteUseBeforeDefinition() throws Exception {
    JSModule[] modules = createModuleStar(
        // m1
        ModuleTestInput.USE,
        // m2
        ModuleTestInput.DEFINITION);

    testSame(modules);
  }

  /**
   * Verifies that the compiler pass's output matches the expected
   * output, and that nodes are annotated with the expected jstype
   * information.
   */
  private void checkTypes(String source,
                          String expected,
                          List<String> expectedTypes) {
    typeInformation.clear();
    test(source, expected);
    assertEquals(expectedTypes, typeInformation);
  }

  @Override
  protected CompilerPass getProcessor(Compiler compiler) {
    return new TypeInformationGatherer(
        compiler, new DevirtualizePrototypeMethods(compiler), typeInformation);
  }

  /**
   * Wrapper that gathers function, call, and self variable type strings after
   * the pass under test runs.  For use to test passes that modify JSType
   * annotations.
   */
  private static class TypeInformationGatherer
      implements CompilerPass {
    private final Compiler compiler;
    private final CompilerPass passUnderTest;
    private final List<String> typeInformation;

    TypeInformationGatherer(Compiler compiler,
                                    CompilerPass passUnderTest,
                                    List<String> typeInformation) {
      this.compiler = compiler;
      this.passUnderTest = passUnderTest;
      this.typeInformation = typeInformation;
    }

    @Override
    public void process(Node externs, Node root) {
      passUnderTest.process(externs, root);
      NodeTraversal.traverseEs6(compiler, externs, new GatherCallback());
      NodeTraversal.traverseEs6(compiler, root, new GatherCallback());
    }

    public String getNameString(Node n) {
      Token type = n.getToken();
      if (type == Token.NAME) {
        return n.getString();
      } else if (type == Token.GETPROP) {
        String left = getNameString(n.getFirstChild());
        if (left == null) {
          return null;
        }
        return left + "." + n.getLastChild().getString();
      } else if (type == Token.GETELEM) {
        String left = getNameString(n.getFirstChild());
        if (left == null) {
          return null;
        }
        return left + "[" + n.getLastChild().getString() + "]";
      } else if (type == Token.THIS) {
        return "this";
      } else if (type == Token.FUNCTION){
        return "{ANON FUNCTION}";
      } else {
        // I wonder if we should just die on this.
        return null;
      }
    }

    private class GatherCallback extends AbstractPostOrderCallback {
      @Override
      public void visit(NodeTraversal traversal, Node node, Node parent) {
        Node nameNode = null;
        if (node.isFunction()) {
          if (parent.isName()) {
            nameNode = parent;
          } else if (parent.isAssign()) {
            nameNode = parent.getFirstChild();
          } else {
            nameNode = node.getFirstChild();
          }
        } else if (node.isCall() || node.isNew()) {
          nameNode = node.getFirstChild();
        }

        if (nameNode != null) {
          JSType type = node.getJSType();
          typeInformation.add(
              Joiner.on("")
                  .join(
                      node.getToken(), " ", getNameString(nameNode), " = ", String.valueOf(type)));
        }

        if (node.isGetProp()) {
          Node child = node.getFirstChild();
          if (child.isName() && child.getString().endsWith("$self")) {
            JSType type = child.getJSType();
            typeInformation.add(
                Joiner.on("")
                    .join(child.getToken(), " ", child.getString(), " = ", String.valueOf(type)));
          }
        }
      }
    }
  }
}