Identifying unparsed keyword token kinds in ParseException (was:

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One way to get ParseException messages to identify keyword tokens with
a <...> string:

1. Change the token expression to be something other than a simple
    string, such as changing from:
      <IF: "if">
    to:
      <IF: "i" "f">
    or to:
      <IF: "if" | "if">

    The result of this should be that after javacc is run,
    PARSERNAMEConstants.tokenImage contains "<IF>" (instead of "\"if\"").

2. Change ParseException.java to combine the
    PARSERNAMEConstants.tokenImage[tok.kind] for the token with the
    add_escapes(tok.image) (instead of just add_escapes(tok.image)).
    For example, attached changes produce <"if"=IF> (instead of "if").

Hope this helps!


Cesare Zecca wrote:

> Exception in thread "main"
> ParseException: Encountered "if" at line 1, column 5.
> Was expecting one of:
>     <PAR_OPEN> ...
>     <NUMBER_LITERAL> ...
>     "-" ...
>     <GROUP_ID> ...
>  
> Anyway, the diagnostic does not mention at all that... "if" is a
> reserved keyword.

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--- old/ParseException.java
+++ new/ParseException.java
@[EMAIL PROTECTED]
 -110,7 +110,7 @[EMAIL PROTECTED]
       }
       expected.append(eol).append("    ");
     }
-    String retval = "Encountered \"";
+    String retval = "Encountered ";
     Token tok = currentToken.next;
     for (int i = 0; i < maxSize; i++) {
       if (i != 0) retval += " ";
@[EMAIL PROTECTED]
 -118,10 +118,15 @[EMAIL PROTECTED]
         retval += tokenImage[0];
         break;
       }
-      retval += add_escapes(tok.image);
+      String kindImage = tokenImage[tok.kind];
+      if (!kindImage.startsWith("<")) {
+        retval += kindImage;
+      } else {
+        retval +=
"<\""+add_escapes(tok.image)+"\"="+kindImage.substring(1);
+      }
       tok = tok.next; 
     }
-    retval += "\" at line " + currentToken.next.beginLine + ", column " +
currentToken.next.beginColumn;
+    retval += " at line " + currentToken.next.beginLine + ", column " +
currentToken.next.beginColumn;
     retval += "." + eol;
     if (expectedTokenSequences.length == 1) {
       retval += "Was expecting:" + eol + "    ";

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