Modify SourceFile to store whether a file is strong, weak or externs.

This is necessary to support eliding weak sources passed under the --weakdep flag from the output.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209794908

src/com/google/javascript/jscomp/Compiler.java

@@ -1787,7 +1787,7 @@ Node parseInputs() {
         }
 
         if (NodeUtil.isFromTypeSummary(n)) {
-          input.setIsExtern(true);
+          input.setIsExtern();
           externsRoot.addChildToBack(n);
         } else {
           jsRoot.addChildToBack(n);
@@ -1991,7 +1991,7 @@ private boolean hoistIfExtern(CompilerInput input) {
       // If the input file is explicitly marked as an externs file, then move it out of the main
       // JS root and put it with the other externs.
       externsRoot.addChildToBack(n);
-      input.setIsExtern(true);
+      input.setIsExtern();
 
       input.getModule().remove(input);
 

src/com/google/javascript/jscomp/CompilerInput.java

@@ -33,6 +33,7 @@
 import com.google.javascript.jscomp.parsing.parser.FeatureSet;
 import com.google.javascript.rhino.InputId;
 import com.google.javascript.rhino.Node;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -70,6 +71,15 @@ public class CompilerInput extends DependencyInfo.Base implements SourceAst {
   private transient AbstractCompiler compiler;
   private transient ModulePath modulePath;
 
+  // TODO(tjgq): Whether a CompilerInput is an externs file is determined by the `isExtern`
+  // constructor argument and the `setIsExtern` method. Both are necessary because, while externs
+  // files passed under the --externs flag are not required to contain an @externs annotation,
+  // externs files passed under any other flag must have one, and the presence of the latter can
+  // only be known once the file has been parsed. To add to the confusion, note that CompilerInput
+  // doesn't actually store the extern bit itself, but instead mutates the SourceFile associated
+  // with the AST node. Once (when?) we enforce that extern files always contain an @externs
+  // annotation, we can store the extern bit in the AST node, and make SourceFile immutable.
+
   public CompilerInput(SourceAst ast) {
     this(ast, ast.getSourceFile().getName(), false);
   }
@@ -86,10 +96,8 @@ public CompilerInput(SourceAst ast, InputId inputId, boolean isExtern) {
     this.ast = ast;
     this.id = inputId;
 
-    // TODO(nicksantos): Add a precondition check here. People are passing
-    // in null, but they should not be.
-    if (ast != null && ast.getSourceFile() != null) {
-      ast.getSourceFile().setIsExtern(isExtern);
+    if (isExtern) {
+      setIsExtern();
     }
   }
 
@@ -498,11 +506,12 @@ public boolean isExtern() {
     return ast.getSourceFile().isExtern();
   }
 
-  void setIsExtern(boolean isExtern) {
+  void setIsExtern() {
+    // TODO(tjgq): Add a precondition check here. People are passing in null, but they shouldn't be.
     if (ast == null || ast.getSourceFile() == null) {
       return;
     }
-    ast.getSourceFile().setIsExtern(isExtern);
+    ast.getSourceFile().setKind(SourceKind.EXTERN);
   }
 
   public int getLineOffset(int lineno) {

src/com/google/javascript/jscomp/SourceFile.java

@@ -25,6 +25,7 @@
 import com.google.common.io.CharStreams;
 import com.google.common.io.Resources;
 import com.google.javascript.rhino.StaticSourceFile;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
@@ -57,6 +58,7 @@
  * @author nicksantos@google.com (Nick Santos)
  */
 public class SourceFile implements StaticSourceFile, Serializable {
+
   private static final long serialVersionUID = 1L;
   private static final String UTF8_BOM = "\uFEFF";
 
@@ -74,7 +76,7 @@ public interface Generator {
   private static final int SOURCE_EXCERPT_REGION_LENGTH = 5;
 
   private final String fileName;
-  private boolean isExternFile = false;
+  private SourceKind kind;
 
   // The fileName may not always identify the original file - for example,
   // supersourced Java inputs, or Java inputs that come from Jar files. This
@@ -94,8 +96,9 @@ public interface Generator {
    * @param fileName The file name of the source file. It does not necessarily need to correspond to
    *     a real path. But it should be unique. Will appear in warning messages emitted by the
    *     compiler.
+   * @param kind The source kind.
    */
-  public SourceFile(String fileName) {
+  public SourceFile(String fileName, SourceKind kind) {
     if (isNullOrEmpty(fileName)) {
       throw new IllegalArgumentException("a source must have a name");
     }
@@ -145,9 +148,6 @@ private void resetLineOffsets() {
     lineOffsets = null;
   }
 
-  //////////////////////////////////////////////////////////////////////////////
-  // Implementation
-
   /**
    * Gets all the code in this source file.
    * @throws IOException
@@ -156,7 +156,6 @@ public String getCode() throws IOException {
     return code;
   }
 
-
   /**
    * Gets a reader for the code in this source file.
    */
@@ -210,15 +209,21 @@ public String getName() {
     return fileName;
   }
 
-  /** Returns whether this is an extern. */
+  /** Returns the source kind. */
   @Override
-  public boolean isExtern() {
-    return isExternFile;
+  public SourceKind getKind() {
+    return kind;
   }
 
-  /** Sets that this is an extern. */
-  void setIsExtern(boolean newVal) {
-    isExternFile = newVal;
+  /**
+   * Sets the source kind.
+   *
+   * <p>TODO(tjgq): Move the extern bit into the AST, so we can make the kind immutable. This is
+   * currently not possible because for some files the extern bit is not determined by the contents
+   * (e.g. files passed under the --externs flag and missing an externs annotation).
+   */
+  void setKind(SourceKind kind) {
+    this.kind = kind;
   }
 
   @Override
@@ -537,7 +542,7 @@ static class Preloaded extends SourceFile {
     private static final long serialVersionUID = 1L;
 
     Preloaded(String fileName, String originalPath, String code) {
-      super(fileName);
+      super(fileName, SourceKind.STRONG);
       super.setOriginalPath(originalPath);
       super.setCode(code);
     }
@@ -556,7 +561,7 @@ static class Generated extends SourceFile {
 
     // Not private, so that LazyInput can extend it.
     Generated(String fileName, String originalPath, Generator generator) {
-      super(fileName);
+      super(fileName, SourceKind.STRONG);
       super.setOriginalPath(originalPath);
       this.generator = generator;
     }
@@ -597,7 +602,7 @@ static class OnDisk extends SourceFile {
     private transient Charset inputCharset = UTF_8;
 
     OnDisk(Path path, String originalPath, Charset c) {
-      super(path.toString());
+      super(path.toString(), SourceKind.STRONG);
       this.path = path;
       setOriginalPath(originalPath);
       if (c != null) {
@@ -670,7 +675,7 @@ private void writeObject(java.io.ObjectOutputStream out) throws Exception {
       out.writeObject(inputCharset != null ? inputCharset.name() : null);
       out.writeObject(path != null ? path.toUri() : null);
     }
-    
+
     @GwtIncompatible("ObjectInputStream")
     private void readObject(java.io.ObjectInputStream in) throws Exception {
       in.defaultReadObject();
@@ -702,9 +707,9 @@ static class AtUrl extends SourceFile {
     private String inputCharset = UTF_8.name();
 
     AtUrl(URL url, String originalPath, Charset c) {
-      super(originalPath);
-      this.url = url;
+      super(originalPath, SourceKind.STRONG);
       super.setOriginalPath(originalPath);
+      this.url = url;
       if (c != null) {
         this.setCharset(c);
       }

src/com/google/javascript/jscomp/SyntheticAst.java

@@ -21,6 +21,7 @@
 import com.google.javascript.rhino.IR;
 import com.google.javascript.rhino.InputId;
 import com.google.javascript.rhino.Node;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 
 /**
  * An AST generated totally by the compiler.
@@ -37,13 +38,13 @@ public final class SyntheticAst implements SourceAst {
 
   SyntheticAst(String sourceName) {
     this.inputId = new InputId(sourceName);
-    this.sourceFile = new SourceFile(sourceName);
+    this.sourceFile = new SourceFile(sourceName, SourceKind.STRONG);
     clearAst();
   }
 
   public SyntheticAst(Node root) {
     this.inputId = new InputId(root.getSourceFileName());
-    this.sourceFile = new SourceFile(root.getSourceFileName());
+    this.sourceFile = new SourceFile(root.getSourceFileName(), SourceKind.STRONG);
     this.root = checkNotNull(root);
   }
 

src/com/google/javascript/rhino/Node.java

@@ -47,6 +47,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Objects;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 import com.google.javascript.rhino.jstype.JSType;
 import java.io.IOException;
 import java.io.ObjectInput;
@@ -1334,7 +1335,7 @@ public final void setStaticSourceFile(@Nullable StaticSourceFile file) {
 
   /** Sets the source file to a non-extern file of the given name. */
   public final void setSourceFileForTesting(String name) {
-    this.putProp(STATIC_SOURCE_FILE, new SimpleSourceFile(name, false));
+    this.putProp(STATIC_SOURCE_FILE, new SimpleSourceFile(name, SourceKind.STRONG));
   }
 
   // TODO(johnlenz): make this final

src/com/google/javascript/rhino/SimpleSourceFile.java

@@ -45,11 +45,11 @@
  */
 public final class SimpleSourceFile implements StaticSourceFile {
   private final String name;
-  private final boolean extern;
+  private final SourceKind kind;
 
-  public SimpleSourceFile(String name, boolean extern) {
+  public SimpleSourceFile(String name, SourceKind kind) {
     this.name = name;
-    this.extern = extern;
+    this.kind = kind;
   }
 
   @Override
@@ -58,8 +58,8 @@ public String getName() {
   }
 
   @Override
-  public boolean isExtern() {
-    return extern;
+  public SourceKind getKind() {
+    return kind;
   }
 
   @Override

src/com/google/javascript/rhino/StaticSourceFile.java

@@ -44,15 +44,39 @@
  * @author nicksantos@google.com (Nick Santos)
  */
 public interface StaticSourceFile {
+
+  /** Source kinds. */
+  public enum SourceKind {
+    /** A file whose contents are necessary both for type checking and emitting code. */
+    STRONG,
+    /** A file whose contents are necessary for type checking only. */
+    WEAK,
+    /** A file whose contents are extern declarations. */
+    EXTERN
+  }
+
   /**
    * The name of the file. Must be unique across all files in the compilation.
    */
   String getName();
 
-  /**
-   * Returns whether this is an externs file.
-   */
-  boolean isExtern();
+  /** The source kind. */
+  SourceKind getKind();
+
+  /** Whether the source kind is STRONG. */
+  default boolean isStrong() {
+    return getKind() == SourceKind.STRONG;
+  }
+
+  /** Whether the source kind is WEAK. */
+  default boolean isWeak() {
+    return getKind() == SourceKind.WEAK;
+  }
+
+  /** Whether the source kind is EXTERN. */
+  default boolean isExtern() {
+    return getKind() == SourceKind.EXTERN;
+  }
 
   /**
    * Returns the offset of the given line number relative to the file start.

test/com/google/javascript/jscomp/AstValidatorTest.java

@@ -28,6 +28,7 @@
 import com.google.javascript.rhino.JSTypeExpression;
 import com.google.javascript.rhino.Node;
 import com.google.javascript.rhino.SimpleSourceFile;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 import com.google.javascript.rhino.Token;
 
 /**
@@ -139,7 +140,7 @@ public void testValidScript() {
     Node n = new Node(Token.SCRIPT);
     expectInvalid(n, Check.SCRIPT);
     n.setInputId(new InputId("something_input"));
-    n.setStaticSourceFile(new SimpleSourceFile("something", false));
+    n.setStaticSourceFile(new SimpleSourceFile("something", SourceKind.STRONG));
     expectValid(n, Check.SCRIPT);
     expectInvalid(n, Check.STATEMENT);
     expectInvalid(n, Check.EXPRESSION);
@@ -534,7 +535,7 @@ public void testValidFeatureInScript() {
 
     Node n = new Node(Token.SCRIPT);
     n.setInputId(new InputId("something_input"));
-    n.setStaticSourceFile(new SimpleSourceFile("something", false));
+    n.setStaticSourceFile(new SimpleSourceFile("something", SourceKind.STRONG));
     expectValid(n, Check.SCRIPT);
 
     n.addChildToFront(IR.let(IR.name("a"), IR.number(3)));
@@ -604,7 +605,7 @@ private Node parseScriptWithoutCheckingLanguageLevel(String code) {
     Node script = n.getFirstChild();
     assertNode(script).hasType(Token.SCRIPT);
     script.setInputId(new InputId("something_input"));
-    script.setStaticSourceFile(new SimpleSourceFile("something", false));
+    script.setStaticSourceFile(new SimpleSourceFile("something", SourceKind.STRONG));
     return script;
   }
 }

test/com/google/javascript/jscomp/CompilerTestCase.java

@@ -35,6 +35,7 @@
 import com.google.javascript.jscomp.type.ReverseAbstractInterpreter;
 import com.google.javascript.jscomp.type.SemanticReverseAbstractInterpreter;
 import com.google.javascript.rhino.Node;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 import com.google.javascript.rhino.testing.BaseJSTypeTestCase;
 import java.io.IOException;
 import java.io.InputStream;
@@ -2316,7 +2317,7 @@ protected static final class Externs implements TestPart {
       externs = files;
       if (files != null) {
         for (SourceFile s : files) {
-          s.setIsExtern(true);
+          s.setKind(SourceKind.EXTERN);
         }
       }
     }

test/com/google/javascript/jscomp/parsing/AttachJsdocsTest.java

@@ -23,6 +23,7 @@
 import com.google.javascript.rhino.JSDocInfo;
 import com.google.javascript.rhino.Node;
 import com.google.javascript.rhino.SimpleSourceFile;
+import com.google.javascript.rhino.StaticSourceFile.SourceKind;
 import com.google.javascript.rhino.Token;
 import com.google.javascript.rhino.testing.BaseJSTypeTestCase;
 import com.google.javascript.rhino.testing.TestErrorReporter;
@@ -795,11 +796,10 @@ private Node parse(String source, String... warnings) {
             null,
             true,
             StrictMode.SLOPPY);
-    Node script = ParserRunner.parse(
-        new SimpleSourceFile("input", false),
-        source,
-        config,
-        testErrorReporter).ast;
+    Node script =
+        ParserRunner.parse(
+                new SimpleSourceFile("input", SourceKind.STRONG), source, config, testErrorReporter)
+            .ast;
 
     // verifying that all warnings were seen
     testErrorReporter.assertHasEncounteredAllErrors();