Merge branch 'sharpen'

reference/antlr4

@@ -1 +1 @@
-Subproject commit 5fb64ac91e36209b99e37a6356e66c41f5e50aab
+Subproject commit 8083e0b659bb318eb4454591648a01d28e07f03e

runtime/CSharp/Antlr4.Runtime/Atn/LexerATNSimulator.cs

@@ -472,7 +472,7 @@ namespace Antlr4.Runtime.Atn
                     PredictionContext newContext = context.GetParent(i);
                     // "pop" return state
                     ATNState returnState = atn.states[returnStateNumber];
-                    ATNConfig c = ATNConfig.Create(returnState, config.Alt, newContext);
+                    ATNConfig c = config.Transform(returnState, newContext, false);
                     currentAltReachedAcceptState = Closure(input, c, configs, currentAltReachedAcceptState, speculative);
                 }
                 return currentAltReachedAcceptState;

runtime/CSharp/Antlr4.Runtime/Atn/ParserATNSimulator.cs

@@ -1319,7 +1319,8 @@ namespace Antlr4.Runtime.Atn
         /// .</li>
         /// <li>Remove all configurations which predict an alternative greater than
         /// 1, for which another configuration that predicts alternative 1 is in the
-        /// same ATN state. This transformation is valid for the following reasons:
+        /// same ATN state with the same prediction context. This transformation is
+        /// valid for the following reasons:
         /// <ul>
         /// <li>The closure block cannot contain any epsilon transitions which bypass
         /// the body of the closure, so all states reachable via alternative 1 are
@@ -1333,6 +1334,35 @@ namespace Antlr4.Runtime.Atn
         /// </ul>
         /// </li>
         /// </ol>
+        /// <p>
+        /// The prediction context must be considered by this filter to address
+        /// situations like the following.
+        /// </p>
+        /// <code>
+        /// <pre>
+        /// grammar TA;
+        /// prog: statement* EOF;
+        /// statement: letterA | statement letterA 'b' ;
+        /// letterA: 'a';
+        /// </pre>
+        /// </code>
+        /// <p>
+        /// If the above grammar, the ATN state immediately before the token
+        /// reference
+        /// <code>'a'</code>
+        /// in
+        /// <code>letterA</code>
+        /// is reachable from the left edge
+        /// of both the primary and closure blocks of the left-recursive rule
+        /// <code>statement</code>
+        /// . The prediction context associated with each of these
+        /// configurations distinguishes between them, and prevents the alternative
+        /// which stepped out to
+        /// <code>prog</code>
+        /// (and then back in to
+        /// <code>statement</code>
+        /// from being eliminated by the filter.
+        /// </p>
         /// </summary>
         /// <param name="configs">
         /// The configuration set computed by
@@ -1349,7 +1379,7 @@ namespace Antlr4.Runtime.Atn
         [return: NotNull]
         protected internal virtual ATNConfigSet ApplyPrecedenceFilter(ATNConfigSet configs, ParserRuleContext globalContext, PredictionContextCache contextCache)
         {
-            HashSet<int> statesFromAlt1 = new HashSet<int>();
+            IDictionary<int, PredictionContext> statesFromAlt1 = new Dictionary<int, PredictionContext>();
             ATNConfigSet configSet = new ATNConfigSet();
             foreach (ATNConfig config in configs)
             {
@@ -1364,7 +1394,7 @@ namespace Antlr4.Runtime.Atn
                     // the configuration was eliminated
                     continue;
                 }
-                statesFromAlt1.Add(config.State.stateNumber);
+                statesFromAlt1.Put(config.State.stateNumber, config.Context);
                 if (updatedContext != config.SemanticContext)
                 {
                     configSet.Add(config.Transform(config.State, updatedContext, false), contextCache);
@@ -1381,7 +1411,8 @@ namespace Antlr4.Runtime.Atn
                     // already handled
                     continue;
                 }
-                if (statesFromAlt1.Contains(config_1.State.stateNumber))
+                PredictionContext context = statesFromAlt1.Get(config_1.State.stateNumber);
+                if (context != null && context.Equals(config_1.Context))
                 {
                     // eliminated
                     continue;
@@ -1785,9 +1816,9 @@ namespace Antlr4.Runtime.Atn
             return config.Transform(t.target, newContext, false);
         }
 
-        private sealed class _IComparer_1741 : IComparer<ATNConfig>
+        private sealed class _IComparer_1771 : IComparer<ATNConfig>
         {
-            public _IComparer_1741()
+            public _IComparer_1771()
             {
             }
 
@@ -1807,7 +1838,7 @@ namespace Antlr4.Runtime.Atn
             }
         }
 
-        private static readonly IComparer<ATNConfig> StateAltSortComparator = new _IComparer_1741();
+        private static readonly IComparer<ATNConfig> StateAltSortComparator = new _IComparer_1771();
 
         private BitSet IsConflicted(ATNConfigSet configset, PredictionContextCache contextCache)
         {

runtime/CSharp/Antlr4.Runtime/ParserInterpreter.cs

@@ -143,10 +143,20 @@ namespace Antlr4.Runtime
                     {
                         // pop; return from rule
                         if (_ctx.IsEmpty())
+                        {
+                            if (startRuleStartState.isPrecedenceRule)
+                            {
+                                ParserRuleContext result = _ctx;
+                                Tuple<ParserRuleContext, int> parentContext = _parentContextStack.Pop();
+                                UnrollRecursionContexts(parentContext.Item1);
+                                return result;
+                            }
+                            else
                             {
                                 ExitRule();
                                 return rootContext;
                             }
+                        }
                         VisitRuleStopState(p);
                         break;
                     }

runtime/CSharp/Antlr4.Runtime/Recognizer`2.cs

@@ -229,6 +229,8 @@ namespace Antlr4.Runtime
         /// your token objects because you don't have to go modify your lexer
         /// so that it creates a new Java type.
         /// </remarks>
+        [Obsolete]
+        [System.ObsoleteAttribute(@"This method is not called by the ANTLR 4 Runtime. Specific implementations of IAntlrErrorStrategy may provide a similar feature when necessary. For example, seeDefaultErrorStrategy.GetTokenErrorDisplay(IToken) .")]
         public virtual string GetTokenErrorDisplay(IToken t)
         {
             if (t == null)