General TypeInfo and IdentifierContext cleanup

* Assert computeType and TypeInfo.skipType do not modify the token stream
* Rename TokenInfoTest to TypeInfoTest
* Move skipMetadata to util.dart
* Address comments in https://dart-review.googlesource.com/c/sdk/+/53300

Change-Id: Id2dbe54c5bc688db268e18b0a491367115f7b091
Reviewed-on: https://dart-review.googlesource.com/53640
Commit-Queue: Dan Rubel <danrubel@google.com>
Reviewed-by: Peter von der Ahé <ahe@google.com>

pkg/front_end/lib/src/fasta/parser/identifier_context_impl.dart

@@ -15,9 +15,9 @@ import 'parser.dart' show Parser;
 import 'type_info.dart'
     show insertSyntheticIdentifierAfter, isValidTypeReference;
 
-import 'util.dart' show optional;
+import 'util.dart' show optional, skipMetadata;
 
-/// See [IdentifierContext].classOrNamedMixin
+/// See [IdentifierContext.classOrNamedMixinDeclaration].
 class ClassOrNamedMixinIdentifierContext extends IdentifierContext {
   const ClassOrNamedMixinIdentifierContext()
       : super('classOrNamedMixinDeclaration',
@@ -53,7 +53,7 @@ class ClassOrNamedMixinIdentifierContext extends IdentifierContext {
   }
 }
 
-/// See [IdentifierContext].dottedName
+/// See [IdentifierContext.dottedName].
 class DottedNameIdentifierContext extends IdentifierContext {
   const DottedNameIdentifierContext() : super('dottedName');
 
@@ -95,7 +95,7 @@ class DottedNameIdentifierContext extends IdentifierContext {
   }
 }
 
-/// See [IdentifierContext].expression
+/// See [IdentifierContext.expression].
 class ExpressionIdentifierContext extends IdentifierContext {
   const ExpressionIdentifierContext()
       : super('expression', isScopeReference: true);
@@ -145,6 +145,7 @@ class ExpressionIdentifierContext extends IdentifierContext {
   }
 }
 
+/// See [IdentifierContext.fieldDeclaration].
 class FieldDeclarationIdentifierContext extends IdentifierContext {
   const FieldDeclarationIdentifierContext()
       : super('fieldDeclaration', inDeclaration: true);
@@ -175,7 +176,7 @@ class FieldDeclarationIdentifierContext extends IdentifierContext {
   }
 }
 
-/// See [IdentifierContext].fieldInitializer
+/// See [IdentifierContext.fieldInitializer].
 class FieldInitializerIdentifierContext extends IdentifierContext {
   const FieldInitializerIdentifierContext()
       : super('fieldInitializer', isContinuation: true);
@@ -234,7 +235,7 @@ class ImportPrefixIdentifierContext extends IdentifierContext {
   }
 }
 
-/// See [IdentifierContext].libraryName
+/// See [IdentifierContext.libraryName].
 class LibraryIdentifierContext extends IdentifierContext {
   const LibraryIdentifierContext()
       : super('libraryName', inLibraryOrPartOfDeclaration: true);
@@ -276,7 +277,7 @@ class LibraryIdentifierContext extends IdentifierContext {
   }
 }
 
-/// See [IdentifierContext].localVariableDeclaration
+/// See [IdentifierContext.localVariableDeclaration].
 class LocalVariableDeclarationIdentifierContext extends IdentifierContext {
   const LocalVariableDeclarationIdentifierContext()
       : super('localVariableDeclaration', inDeclaration: true);
@@ -308,6 +309,7 @@ class LocalVariableDeclarationIdentifierContext extends IdentifierContext {
   }
 }
 
+/// See [IdentifierContext.methodDeclaration].
 class MethodDeclarationIdentifierContext extends IdentifierContext {
   const MethodDeclarationIdentifierContext()
       : super('methodDeclaration', inDeclaration: true);
@@ -383,7 +385,7 @@ class TypedefDeclarationIdentifierContext extends IdentifierContext {
   }
 }
 
-/// See [IdentifierContext].typeReference
+/// See [IdentifierContext.typeReference].
 class TypeReferenceIdentifierContext extends IdentifierContext {
   const TypeReferenceIdentifierContext()
       : super('typeReference',
@@ -415,7 +417,7 @@ class TypeReferenceIdentifierContext extends IdentifierContext {
       // annotation is not allowed before type arguments.
       parser.reportRecoverableErrorWithToken(
           next, fasta.templateUnexpectedToken);
-      token = skipMetadata(next);
+      token = skipMetadata(token);
       next = token.next;
     }
 
@@ -490,25 +492,3 @@ bool looksLikeStartOfNextStatement(Token token) => isOneOfOrEof(token, const [
 bool looksLikeStartOfNextTopLevelDeclaration(Token token) =>
     token.isTopLevelKeyword ||
     isOneOfOrEof(token, const ['const', 'get', 'final', 'set', 'var', 'void']);
-
-Token skipMetadata(Token token) {
-  assert(optional('@', token));
-  Token next = token.next;
-  if (next.isIdentifier) {
-    token = next;
-    next = token.next;
-    while (optional('.', next)) {
-      token = next;
-      next = token.next;
-      if (next.isIdentifier) {
-        token = next;
-        next = token.next;
-      }
-    }
-    if (optional('(', next)) {
-      token = next.endGroup;
-      next = token.next;
-    }
-  }
-  return token;
-}

pkg/front_end/lib/src/fasta/parser/util.dart

@@ -53,3 +53,26 @@ int lengthOfSpan(Token begin, Token end) {
   if (end == null) return lengthForToken(begin);
   return end.offset + end.length - begin.offset;
 }
+
+Token skipMetadata(Token token) {
+  token = token.next;
+  assert(optional('@', token));
+  Token next = token.next;
+  if (next.isIdentifier) {
+    token = next;
+    next = token.next;
+    while (optional('.', next)) {
+      token = next;
+      next = token.next;
+      if (next.isIdentifier) {
+        token = next;
+        next = token.next;
+      }
+    }
+    if (optional('(', next)) {
+      token = next.endGroup;
+      next = token.next;
+    }
+  }
+  return token;
+}

pkg/front_end/test/fasta/parser/type_info_test.dart

@@ -13,12 +13,12 @@ import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 main() {
   defineReflectiveSuite(() {
-    defineReflectiveTests(TokenInfoTest);
+    defineReflectiveTests(TypeInfoTest);
   });
 }
 
 @reflectiveTest
-class TokenInfoTest {
+class TypeInfoTest {
   void test_noType() {
     final Token start = scanString('before ;').tokens;
 
@@ -790,12 +790,18 @@ void compute(
     String expectedAfter,
     List<String> expectedCalls,
     List<ExpectedError> expectedErrors) {
+  int expectedGtGtAndNullEndCount = countGtGtAndNullEnd(start);
   TypeInfo typeInfo = computeType(start, required);
   expect(typeInfo, expectedInfo, reason: source);
+  expect(countGtGtAndNullEnd(start), expectedGtGtAndNullEndCount,
+      reason: 'computeType should not modify the token stream');
+
   if (typeInfo is ComplexTypeInfo) {
     expect(typeInfo.start, start.next, reason: source);
     expect(typeInfo.couldBeExpression, isFalse);
     expectEnd(expectedAfter, typeInfo.skipType(start));
+    expect(countGtGtAndNullEnd(start), expectedGtGtAndNullEndCount,
+        reason: 'TypeInfo.skipType should not modify the token stream');
 
     TypeInfoListener listener;
     assertResult(Token actualEnd) {
@@ -838,6 +844,18 @@ Token scan(String source) {
   return new SyntheticToken(TokenType.EOF, 0)..setNext(start);
 }
 
+int countGtGtAndNullEnd(Token token) {
+  int count = 0;
+  while (!token.isEof) {
+    if ((optional('<', token) && token.endGroup == null) ||
+        optional('>>', token)) {
+      ++count;
+    }
+    token = token.next;
+  }
+  return count;
+}
+
 class TypeInfoListener implements Listener {
   List<String> calls = <String>[];
   List<ExpectedError> errors;