#146 : alternate non terminals

b3b00 · Jan 2, 2020 · aa1130a · aa1130a
1 parent 3236506
commit aa1130a
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Showing 2 changed files with 54 additions and 6 deletions.
diff --git a/ParserTests/EBNFTests.cs b/ParserTests/EBNFTests.cs
@@ -203,7 +203,7 @@ public int TestTerminal(List<Token<GroupTestToken>> options, Token<GroupTestToke
     }
 
 
-    public class AlternateChoiceTest
+    public class AlternateChoiceTestTerminal
     {
         [Production("choice : [ a | b | c]")]
         public string Choice(Token<OptionTestToken> c)
@@ -228,6 +228,34 @@ public string C(Token<OptionTestToken> c)
 
     }
 
+    public class AlternateChoiceTestNonTerminal
+    {
+        [Production("choice : [ A | B | C]")]
+        public string Choice(Token<OptionTestToken> c)
+        {
+            return c.Value;
+        }
+
+        [Production("C : c")]
+        public string C(Token<OptionTestToken> t)
+        {
+            return $"C({t.Value})";
+        }
+
+        [Production("B : b")]
+        public string B(Token<OptionTestToken> t)
+        {
+            return $"B({t.Value})";
+        }
+
+        [Production("A : a")]
+        public string A(Token<OptionTestToken> t)
+        {
+            return $"A({t.Value})";
+        }
+
+    }
+
     public class Bugfix104Test
     {
         [Production("testNonTerm : sub (COMMA[d] unreachable)? ")]
@@ -729,10 +757,10 @@ public void TestBug104()
         }
 
         [Fact]
-        public void TestAlternateChoice()
+        public void TestAlternateChoiceTerminal()
         {
             var startingRule = $"choice";
-            var parserInstance = new AlternateChoiceTest();
+            var parserInstance = new AlternateChoiceTestTerminal();
             var builder = new ParserBuilder<OptionTestToken, string>();
             var builtParser = builder.BuildParser(parserInstance, ParserType.EBNF_LL_RECURSIVE_DESCENT, startingRule);
             Assert.False(builtParser.IsError);
@@ -746,6 +774,25 @@ public void TestAlternateChoice()
             parseResult = builtParser.Result.Parse("d", "choice");
             Assert.False(parseResult.IsOk);
         }
+
+        [Fact]
+        public void TestAlternateChoiceNonTerminal()
+        {
+            var startingRule = $"choice";
+            var parserInstance = new AlternateChoiceTestNonTerminal();
+            var builder = new ParserBuilder<OptionTestToken, string>();
+            var builtParser = builder.BuildParser(parserInstance, ParserType.EBNF_LL_RECURSIVE_DESCENT, startingRule);
+            Assert.False(builtParser.IsError);
+            Assert.False(builtParser.Errors.Any());
+            var parseResult = builtParser.Result.Parse("a", "choice");
+            Assert.True(parseResult.IsOk);
+            parseResult = builtParser.Result.Parse("b", "choice");
+            Assert.True(parseResult.IsOk);
+            parseResult = builtParser.Result.Parse("c", "choice");
+            Assert.True(parseResult.IsOk);
+            parseResult = builtParser.Result.Parse("d", "choice");
+            Assert.False(parseResult.IsOk);
+        }
 
         [Fact]
         public void TestAlternateChoiceErrorMixedTerminalAndNonTerminal()

diff --git a/sly/parser/generator/ParserBuilder.cs b/sly/parser/generator/ParserBuilder.cs
@@ -342,11 +342,12 @@ private static BuildResult<Parser<IN, OUT>> CheckAlternates(BuildResult<Parser<I
                         {
                             if (clause is ChoiceClause<IN> choice)
                             {
-                                bool allTheSame = choice.Choices.Select(c => c is TerminalClause<IN>).Aggregate((x, y) => x && y);
-                                if (!allTheSame)
+                                bool allTerminals = choice.Choices.Select(c => c is TerminalClause<IN>).Aggregate((x, y) => x && y);
+                                bool allNonTerminals = choice.Choices.Select(c => c is NonTerminalClause<IN>).Aggregate((x, y) => x && y);
+                                if (!allNonTerminals && !allTerminals)
                                 {
                                     result.AddError(new ParserInitializationError(ErrorLevel.ERROR,
-                                        $"{rule.RuleString} contains {choice.ToString()} with mixed terminal and nonterminal."));
+                                        $"{rule.ToString()} contains {choice.ToString()} with mixed terminal and nonterminal."));
                                 }
                             } 
                         }