Berkeley Yacc

Berkeley Yacc (byacc) is a Unix parser generator designed to be compatible with Yacc. It was originally written by Robert Corbett and released in 1989.[2] Due to its liberal license and because it was faster than the AT&T Yacc, it quickly became the most popular version of Yacc.[3] It has the advantages of being written in ANSI C89 and being public domain software.

Berkeley Yacc
Original author(s)Robert Corbett
Developer(s)Thomas Dickey
Initial releaseSeptember 2, 1989 (1989-09-02)[1]
Stable release
20200330 / March 30, 2020 (2020-03-30)
Repository
Written inANSI C89
Operating systemUnix-like
TypeParser generator
Licensepublic domain
Websiteinvisible-island.net/byacc/

It contains features not available in Yacc, such as reentrancy, which is implemented in a way that is broadly compatible with GNU Bison.[4][5]

History

In 1985, Robert Corbett developed an original LALR parser generator based on a 1982 paper by DeRemer and Pennello.[6] Corbett wrote it as part of his research towards the Ph.D. he received from University of California, Berkeley in June 1985.[7][8] It was originally named Byson and was incompatible with Yacc but it was subsequently renamed Bison and became the basis of GNU Bison.

Later in 1985, Corbett derived another Yacc-compatible LALR parser generator originally named Zeus but subsequently renamed Zoo.[9] Corbett published the source code for Zoo in a Usenet newsgroup but it went mostly unnoticed until later in September 1989 when Corbett posted on the comp.compilers newsgroup about putting the source code on an FTP server.[1] There was discussion about renaming it and by October 1989 it had become known as Berkeley Yacc (byacc).[10]

In 1995, Chris Dodd developed BtYacc, a backtracking derivative of Berkeley Yacc to support parsing context-sensitive languages like C++,[11][12] based on a 1993 paper by Merrill describing similar modifications to AT&T Yacc.[13][14] It offers backtracking and semantic disambiguation for parsing ambiguous grammar. A rule parsed but rejected by semantic information can be rolled back, so that the parser can try another rule.[15][16] However, it has also been criticized for needing side-effect free trial actions and its inflexible handling of shift-reduce conflicts.[17]

In 1997, Vadim Maslov took over maintenance of BtYacc to support a COBOL parser developed by his company.[18] By 1999, the last 3.0 release, had been converted to C++, no longer supporting from C.[19]

In 2000, Thomas E. Dickey, ported Berkeley Yacc to VMS to facilitate porting tin to VMS. After failing to find another maintainer, Dickey has maintained Berkeley Yacc since February 2002.[20] A significant update was the conversion from K&R C to ANSI C89.[20]

In 2014, Tom Shields integrated BtYacc backtracking into Berkeley Yacc effectively subsuming BtYacc and again supporting C (instead of only C++) in Dickey releases since April 2014.[21]

See also
  • GNU Bison - another free software replacement for Yacc, sharing the same author as Berkeley Yacc.

References
  1. Corbett, Robert (September 2, 1989). "PD LALR(1) parser generator". Newsgroup: comp.compilers. Usenet: 1989Sep2.134244.1611@esegue.uucp. Retrieved 2017-08-26.
  2. Doug Brown; John Levine; Tony Mason (October 1992), lex & yacc (2 ed.), O'Reilly Media
  3. John Levine (August 2009), flex & bison, O'Reilly Media
  4. "Berkeley Yacc". ...support for reentrant code, which has evolved in byacc to the point where it can be compared and tuned against bison.
  5. Berkeley Yacc Change log, see entry "2010-06-07 Andres.Meji"
  6. DeRemer, Frank; Pennello, Thomas (October 1982). "Efficient Computation of LALR(1) Look-Ahead Sets" (PDF). ACM Trans. Program. Lang. Syst. ACM. 4 (4): 615–649. doi:10.1145/69622.357187. ISSN 0164-0925. Retrieved 2017-08-26.
  7. Corbett, Robert (September 24, 1998). "Re: Anyone extended MAXTABLE in yacc parsers?". Newsgroup: comp.compilers. Usenet: 98-09-125@comp.compilers. Retrieved 2017-08-26.
  8. Corbett, Robert Paul (June 1985). Static Semantics and Compiler Error Recovery (Ph.D.). University of California, Berkeley. DTIC ADA611756.
  9. Corbett, Robert (September 6, 1989). "Name that PD parser generator". Newsgroup: comp.compilers. Usenet: 1989Sep6.152554.318@esegue.segue.boston.ma.us. Retrieved 2017-08-26.
  10. Corbett, Robert (October 3, 1989). "Berkeley Yacc (new version)". Newsgroup: comp.compilers. Usenet: 1989Oct3.230634.1007@esegue.segue.boston.ma.us. Retrieved 2017-08-26.
  11. Dodd, Chris (March 7, 1995). "BTYACC -- yacc with backtracking and inherited attributes". Newsgroup: comp.compilers. Usenet: 95-03-044@comp.compilers. Retrieved 2020-05-18.
  12. "README.txt". BtYacc: BackTracking Yacc. Siber Systems. Retrieved 2020-05-14.
  13. "README.BYACC". Backtracking yacc. GitHub. Retrieved 2020-05-14.
  14. Merrill, Gary H. (August 1, 1993). "Parsing Non-LR(k) grammars with yacc". Softw. Pract. Exp. 23 (8): 829–850. CiteSeerX 10.1.1.14.1958. doi:10.1002/spe.4380230803. ISSN 0038-0644. Retrieved 2020-05-14.
  15. "btyacc(1)". Debian stretch — Debian Manpages.
  16. Dodd, Chris (13 February 2019). "ChrisDodd/btyacc". GitHub.
  17. Thurston, Adrian D.; Cordy, James R. (2006). "A Backtracking LR Algorithm for Parsing Ambiguous Context-Dependent Languages" (PDF). In Erdogmus, Hakan; Stroulia, Eleni; Stewart, Darlene A. (eds.). Proceedings of the 2006 conference of the Centre for Advanced Studies on Collaborative Research, October 16-19, 2006, Toronto, Ontario, Canada. CASCON 2006. pp. 39–53. CiteSeerX 10.1.1.518.7094. doi:10.1145/1188966.1188972. Retrieved 2020-05-14.
  18. Maslov, Vadim (October 8, 1997). "Version 1.1 of BtYacc (Backtracking Yacc) is available". Newsgroup: comp.compilers. Usenet: 97-10-039@comp.compilers. Retrieved 2020-05-18.
  19. "BtYacc: BackTracking Yacc Parser Generator". Siber Systems. Retrieved 2020-05-18.
  20. "BYACC - BERKELEY YACC". invisible-island.net. Archived from the original on 2002-04-06.
  21. "Release t20140407". ThomasDickey/byacc-snapshots. GitHub. Retrieved 2020-05-18.
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