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1.1 root 1: From phr Tue Jul 8 10:36:19 1986
2: Date: Tue, 8 Jul 86 00:52:24 EDT
3: From: phr (Paul Rubin)
4: To: riferguson%[email protected], tower
5: Subject: Re: Bison documentation?
6:
7: The main difference between Bison and Yacc that I know of is that
8: Bison supports the @N construction, which gives you access to
9: the starting and ending line number and character number associated
10: with any of the symbols in the current rule.
11:
12: Also, Bison supports the command `%expect N' which says not to mention
13: the conflicts if there are N shift/reduce conflicts and no reduce/reduce
14: conflicts.
15:
16: The differences in the algorithms stem mainly from the horrible
17: kludges that Johnson had to perpetrate to make Yacc fit in a PDP-11.
18:
19: Also, Bison uses a faster but less space-efficient encoding for the
20: parse tables (see Corbett's PhD thesis from Berkeley, "Static
21: Semantics in Compiler Error Recovery", June 1985, Report No. UCB/CSD
22: 85/251), and more modern technique for generating the lookahead sets.
23: (See "Efficient Construction of LALR(1) Lookahead Sets" by F. DeRemer
24: and A. Pennello, in ACM TOPLS Vol 4 No 4, October 1982. Their
25: technique is the standard one now.)
26:
27: paul rubin
28: free software foundation
29:
30:
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