diff options
author | David E. O'Brien <obrien@FreeBSD.org> | 2000-01-17 11:31:33 +0000 |
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committer | David E. O'Brien <obrien@FreeBSD.org> | 2000-01-17 11:31:33 +0000 |
commit | 177ea6b5ae2110667ac2b6ddf28e1d39053058b1 (patch) | |
tree | ba3634b731619d69f125362f92561faadf258232 /devel/bison-devel/pkg-descr | |
parent | Update to 0.99.6 (diff) |
With Bison being shown the door in 4.0-CURRENT, we need the Bison port back.
Notes
Notes:
svn path=/head/; revision=24789
Diffstat (limited to 'devel/bison-devel/pkg-descr')
-rw-r--r-- | devel/bison-devel/pkg-descr | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/devel/bison-devel/pkg-descr b/devel/bison-devel/pkg-descr new file mode 100644 index 000000000000..c968b052baf7 --- /dev/null +++ b/devel/bison-devel/pkg-descr @@ -0,0 +1,22 @@ +Bison is a tool used to write parsers, such as the parser for GNU cc. +It is similar to Yacc, which is included in the base FreeBSD system. + +The main difference between Bison and Yacc that I know of is that +Bison supports the @N construction, which gives you access to +the starting and ending line number and character number associated +with any of the symbols in the current rule. + +Also, Bison supports the command `%expect N' which says not to mention +the conflicts if there are N shift/reduce conflicts and no reduce/reduce +conflicts. + +The differences in the algorithms stem mainly from the horrible +kludges that Johnson had to perpetrate to make Yacc fit in a PDP-11. + +Also, Bison uses a faster but less space-efficient encoding for the +parse tables (see Corbett's PhD thesis from Berkeley, "Static +Semantics in Compiler Error Recovery", June 1985, Report No. UCB/CSD +85/251), and more modern technique for generating the lookahead sets. +(See "Efficient Construction of LALR(1) Lookahead Sets" by F. DeRemer +and A. Pennello, in ACM TOPLS Vol 4 No 4, October 1982. Their +technique is the standard one now.) |