Merge pull request #6039 from BZngr/PRContextExtensionsNRE

Author: Vogel612

Rubberduck.Parsing/ParserRuleContextExtensions.cs

@@ -35,6 +35,11 @@ public static Selection GetSelection(this ParserRuleContext context)
         /// </summary>
         public static bool Contains(this ParserRuleContext context, ParserRuleContext otherContextInSameParseTree)
         {
+            if (context is null || otherContextInSameParseTree is null)
+            {
+                return false;
+            }
+
             return context.start.TokenIndex <= otherContextInSameParseTree.start.TokenIndex
                    && context.stop.TokenIndex >= otherContextInSameParseTree.stop.TokenIndex;
         }
@@ -44,7 +49,7 @@ public static bool Contains(this ParserRuleContext context, ParserRuleContext ot
         /// </summary>
         public static IEnumerable<IToken> GetTokens(this ParserRuleContext context, CommonTokenStream tokenStream)
         {
-            var sourceInterval = context.SourceInterval;
+            var sourceInterval = context?.SourceInterval ?? Interval.Invalid;
             if (sourceInterval.Equals(Interval.Invalid) || sourceInterval.b < sourceInterval.a)
             {
                 return new List<IToken>();
@@ -58,7 +63,7 @@ public static IEnumerable<IToken> GetTokens(this ParserRuleContext context, Comm
         public static string GetText(this ParserRuleContext context, ICharStream stream)
         {
             // Can be null if the input is empty it seems.
-            if (context.Stop == null)
+            if (context?.Stop == null)
             {
                 return string.Empty;
             }
@@ -86,7 +91,7 @@ public static TContext GetChild<TContext>(this ParserRuleContext context) where
         /// <summary>
         /// Determines if any of the context's ancestors are the generic Type.
         /// </summary>
-        public static bool IsDescendentOf<TContext>(this ParserRuleContext context)
+        public static bool IsDescendentOf<TContext>(this ParserRuleContext context) where TContext: ParserRuleContext
         {
             if (context == null)
             {
@@ -129,7 +134,7 @@ private static bool IsDescendentOf_Recursive(IParseTree context, IParseTree targ
         /// <summary>
         /// Returns the context's first ancestor of the generic Type.
         /// </summary>
-        public static TContext GetAncestor<TContext>(this ParserRuleContext context)
+        public static TContext GetAncestor<TContext>(this ParserRuleContext context) where TContext: ParserRuleContext
         {
             switch (context)
             {
@@ -145,13 +150,13 @@ public static TContext GetAncestor<TContext>(this ParserRuleContext context)
         /// <summary>
         /// Tries to return the context's first ancestor of the generic Type.
         /// </summary>
-        public static bool TryGetAncestor<TContext>(this ParserRuleContext context, out TContext ancestor)
+        public static bool TryGetAncestor<TContext>(this ParserRuleContext context, out TContext ancestor) where TContext : ParserRuleContext
         {
             ancestor = context.GetAncestor<TContext>();
             return ancestor != null;
         }
 
-        private static TContext GetAncestor_Recursive<TContext>(ParserRuleContext context)
+        private static TContext GetAncestor_Recursive<TContext>(ParserRuleContext context) where TContext: ParserRuleContext
         {
             switch (context)
             {
@@ -258,7 +263,7 @@ public static bool TryGetChildContext<TContext>(this ParserRuleContext ctxt, out
         public static VBAParser.EndOfLineContext GetFirstEndOfLine(this VBAParser.EndOfStatementContext endOfStatement)
         {
             //This dedicated method exists for performance reasons on hot-paths.
-            var individualEndOfStatements = endOfStatement.individualNonEOFEndOfStatement();
+            var individualEndOfStatements = endOfStatement?.individualNonEOFEndOfStatement();
 
             if (individualEndOfStatements == null)
             {