Updated spec_parser such that it runs with ANTLR v4

Change-Id: Ib0711ebc125f4fadb5a526c3538d5c3a35f11234
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/97320
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>

tools/spec_parser/SpecParser.java

@@ -4,13 +4,52 @@
 
 import java.io.*;
 import java.util.*;
-import org.antlr.runtime.*;
+import org.antlr.v4.runtime.*;
+import org.antlr.v4.runtime.dfa.*;
+import org.antlr.v4.runtime.atn.*;
 
 class ParsingResult {
   public int numberOfFileArguments;
   public int numberOfFailures;
 }
 
+class DartErrorListener implements ANTLRErrorListener {
+  public void reportAmbiguity(
+      Parser recognizer,
+      DFA dfa,
+      int startIndex,
+      int stopIndex,
+      boolean exact,
+      BitSet ambigAlts,
+      ATNConfigSet configs) {}
+
+  public void reportAttemptingFullContext(
+      Parser recognizer,
+      DFA dfa,
+      int startIndex,
+      int stopIndex,
+      BitSet conflictingAlts,
+      ATNConfigSet configs) {}
+
+  public void reportContextSensitivity(
+      Parser recognizer,
+      DFA dfa,
+      int startIndex,
+      int stopIndex,
+      int prediction,
+      ATNConfigSet configs) {}
+
+  public void syntaxError(
+      Recognizer<?,?> recognizer,
+      Object offendingSymbol,
+      int line,
+      int charPositionInLine,
+      String msg,
+      RecognitionException e) {
+    if (!DartParser.errorHasOccurred) DartParser.prepareForErrors();
+  }
+}
+
 /// Class for `main` which will parse files given as command line arguments.
 public class SpecParser {
   private static void normalExit() {
@@ -83,8 +122,11 @@ public class SpecParser {
         continue;
       }
       if (verbose) System.err.println("Parsing file: " + filePath);
-      DartParser parser = new DartParser(new CommonTokenStream(
-          new DartLexer(new ANTLRFileStream(filePath))));
+      DartLexer lexer = new DartLexer(new ANTLRFileStream(filePath));
+      DartParser parser = new DartParser(new CommonTokenStream(lexer));
+      ANTLRErrorListener errorListener = new DartErrorListener();
+      lexer.addErrorListener(errorListener);
+      parser.addErrorListener(errorListener);
       if (!parser.parseLibrary(filePath)) result.numberOfFailures++;
     }
     return result;