Announcing Ox release 1.6.1

Tom Shields <>
Thu, 7 Nov 2019 15:30:41 -0600

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Announcing Ox release 1.6.1 (Tom Shields) (2019-11-07)
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From: Tom Shields <>
Newsgroups: comp.compilers
Date: Thu, 7 Nov 2019 15:30:41 -0600
Organization: Compilers Central
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Keywords: tools, available, attribute
Posted-Date: 07 Nov 2019 16:41:23 EST

Ox version 1.6.1 is now available on SourceForge

Ox generalizes the function of Yacc in the way that an attribute
grammar generalizes a context-free grammar. Ordinary Yacc and Lex
specifications may be augmented with definitions of synthesized and
inherited attributes written in C syntax. Ox checks these
specifications for consistency and completeness, and generates from
them a program that builds and decorates attributed parse trees. The
user may specify postdecoration traversals for easy ordering of side
effects, such as code generation. Ox handles the tedious and
error-prone details of writing code for parse-tree management, so its
use eases problems of security and maintainability associated with
that aspect of translator development.


* Noteworthy changes in release 1.6.1 (29 October 2019)

** Enhancements

        Ox now treats multiple Yacc `%union' declarations as does `bison'.

        An attribute reference with a missing trailing '@' is now accepted (with a
        warning) in the evaluation expression of an attribute definition

        An attribute occurrence in an attribute definition explicit and mixed mode
        dependent list, and in an explicit mode dependee list, may now be enclosed
        within '@' symbols.

** Internals

        The Ox parser and lexers were restructured:
        - Lexical information is now passed to the parser via Yacc attributes,
            rather than via global variables.
        - Code related to the lexical analysis of AG specifications was moved out of
            the parser and into the lexers.
        - AG specification transformation code, generating Yacc & Lex compliant
            specifications, was moved out of the lexers and into the parser.
        - Semantic tree traversal code generation was repackaged.

        Message generation was reimplemented to use printf-style format strings with
        variable argument lists.

        The Ox parser now implements `error' token assisted error recovery, and
        `bison' location processing. The parser specification also uses bison 3.0+
        extensions to improve syntax error diagnostics, and uses a custom skeleton
        (derived from the default C skeleton in bison 3.4) to customize format of
        syntax error messages.

        The Ox parser will now only build from scratch with bison 3.4+.

** Bug fixes

        Corrected handling of pre-Standard C string continuations.

        Ox now removes all output files after fatal errors, unless the "-j"
        command-line option is used.

        Ox now diagnoses multiple @revorder dynamic traversal modifiers correctly.

        Corrected a segfault caused by contorted usage of `@revdirection'.

        Corrected a segfault caused by a duplicated attribute.

        Corrected the Ox "-n" command-line option (neutralize semantic actions)
        implementation to always generate compilable code.

** Documentation


** Test suite

        Test cases for syntactic and semantic errors were added to improve code

        The selected lexer and parser generators are now run on all Ox-generated
        lexer & parser files, with the exception of the stripped files.

** Build system

        The `configure' script now includes version information in the configuration

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