This page contains release notes and known issues for the old versions of JTB, as well as features we had planned to implement in newer versions.  The release notes for the current version may be obtained here.

Release Notes for JTB 1.0

• Changes between versions 0.9.0a and 1.0:
• Default visitor method names are now overloaded, each with the name visit(SomeNode n) as opposed to the previous naming scheme of visitSomeNode(SomeNode n).
• Added command-line option "-vn" to generate files using the older naming scheme (for backward compatiblity).

Known Issues for JTB 1.0

• Java blocks within productions.
• Productions containing Java blocks will cause problems in the Visitor.java file.  Each visit() method has a set of comments above them showing which fields correspond to which part of the production.  When Java blocks appear in the production, they (incorrectly) are added to the comments, but without the "//" to denote a comment.
• This probably should not cause any problems since we are unable to think of any situation where a JTB grammar would need Java code within a production.  However, if your grammar for some reason requires Java code within a production, a solution is to manually edit Visitor.java remove the erroneous lines from the file.
• Certain lookahead productions are tagged as errors during parsing by JTB.
• A bug was reported with the C++ grammar included with JavaCC 0.6.1.  Certain lookaheads may cause JTB to report an error when they are actually correct.  The specific lookahead in the C ++ grammar was as follows:

LOOKAHEAD( { sym.IsFullyScopedTypeName(GetFullyScopedName()) } )

• Workaround: put a semicolon after the Java expression.
• JAVACODE productions cause JTB to produce erroneous output.
• JTB will attempt to put JAVACODE productions in the tree, even if the production is of return type void.  For example:

JAVACODE

void skip_to_matching_braces() {

   // Code to eat tokens until a matching brace is found

}



void NT() : { }

{

   A() skip_to_matching_braces()

}

This will cause JTB to attempt to construct a node of type NT with children of type A and skip_to_matching_braces,which is incorrect.
• Workaround steps:
1. Make a "dummy" class with the name of your JAVACODE production.  You can copy one of the classes in the syntaxtree directory and remove all the child references.
2. Change the return value of the JAVACODE production to the name of the production.
3. Add something along the lines of

return new your_production_name();

at the end of the Java code.
• There is no way to access JavaCC special tokens.
• This was overlooked in the design of JTB 1.0, unfortunately.
• The next version of JTB will allow special tokens to be accessed in the tree, if desired (available in JTB 1.1pre3 and later).
• Extraneous parentheses cause JTB to produce erroneous output.
• Parentheses within a nonterminal should only be used in special constructs, such as optionals, lists, or optional lists.
• Extra sets of parentheses cause JTB to improperly annotate the grammar and syntax tree class for the offending nonterminal.
• A semantic checker will be added to JTB 1.1 to catch problem grammars such as these.

Planned Features

• Visitor will be made an interface.  The current default visitor will be renamed to DepthFirstVisitor and will implement the Visitor interface. Available in 1.1pre3.
• A semantic analysis phase will be added to JTB to detect things which JavaCC allows but are unneeded or unused by JTB.  For example, a warning will be issued for the following situations:
• When productions have a return value other than void since JTB automatically alters the return value of all productions in the annotated grammar.
• For blocks of Java code within productions since to our knowledge they are generally unnecessary in JTB grammars.
• When any productions have a name reserved by an automatically generated JTB class (e.g. Node, NodeList, etc.)
• JTB may be equipped with the ability to generate a sort of toolkit of visitors for a grammar, including the aforementioned DepthFirstTraversal and a Scheme tree generator.  Scheme tree generator implemented in 1.1pre1, tree formatter and dumper available in 1.1pre4.
• Accessor methods such as getF0() may be added to preserve encapsulation.  The children references of the nodes will be made private if we decide to do this.
• Memory usage will be improved.  Available in 1.1pre1 and later.
• The JavaPrinter example will be updated for use with JavaCC 0.7.  done
• JavaCC special tokens will be made available in the JTB-generated parse tree.  Available in 1.1pre2.
• Users have requested that the JavaCC Token fields beginLine, endLine, beginColumn, and endColumn be added to the NodeToken class.  So that special tokens also have access to these values, the structure of storing special tokens currently implemented in 1.1pre2 will have to be altered.  Rather than storing a Vector of Strings, it will store a Vector of NodeTokens.  These will be all the special tokens preceding the current token.  Available in 1.1pre3.
• A parent reference may be added to the Node interface.
• We are investigating the idea of automatically generating a skeleton pretty printer visitor which the user can tailor to the grammar. Available in 1.1pre4.

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