Improve error message when a lexical/parsing error occurs when readin…

…g from FileStream
IronScheme · Feb 15, 2022 · e6c2c8f · e6c2c8f
1 parent 4781c74
commit e6c2c8f
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Showing 2 changed files with 14 additions and 2 deletions.
diff --git a/IronScheme/IronScheme/IronSchemeLanguageContext.cs b/IronScheme/IronScheme/IronSchemeLanguageContext.cs
@@ -137,6 +137,15 @@ internal static object ReadExpressions(Stream code, CompilerContext cc)
       {
         return p.parsed;
       }
+
+      if (code is FileStream)
+      {
+        var filename = ((FileStream)code).Name;
+        var errorMsg = p.GetLastError(filename);
+
+        return Builtins.LexicalError("invalid syntax", errorMsg);
+      }
+
       return Builtins.LexicalError("invalid syntax", code);
     }
 
@@ -158,7 +167,6 @@ internal static object ReadExpressions(string code, CompilerContext cc)
         return p.parsed;
       }
       return Builtins.LexicalError("invalid syntax", code);
-
     }
 
     internal static CodeBlock Compile(Cons expr)

diff --git a/IronScheme/IronScheme/gppg/ShiftReduceParser.cs b/IronScheme/IronScheme/gppg/ShiftReduceParser.cs
@@ -199,13 +199,17 @@ public bool ErrorRecovery()
       return discard;
     }
 
+    public string GetLastError(string filename)
+    {
+      return string.Format("unexpected {0} in '{1}' at {2}", TerminalToString(next), filename, GetLocation(lastL));
+    }
 
     public void ReportError()
     {
       StringBuilder errorMsg = new StringBuilder();
       errorMsg.AppendFormat("unexpected {0}", TerminalToString(next));
 
-      if (current_state.parser_table.Count < 20)
+      if (current_state.parser_table != null && current_state.parser_table.Count < 20)
       {
         bool first = true;
         foreach (int terminal in current_state.parser_table.Keys)