30 Mar 2003 21:19:22 -0500

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parsing theory dubts davide.rizzo78@tin.it (Davide Rizzo) (2003-03-30) |

Re: parsing theory dubts haberg@math.su.se (2003-03-30) |

From: | haberg@math.su.se (Hans Aberg) |

Newsgroups: | comp.compilers |

Date: | 30 Mar 2003 21:19:22 -0500 |

Organization: | Mathematics |

References: | 03-03-177 |

Keywords: | parse, comment |

Posted-Date: | 30 Mar 2003 21:19:22 EST |

"Davide Rizzo" <davide.rizzo78@tin.it> wrote:

*>[... LALR is a superset of LL. ... -John]*

Thise is not entirely true. Here is a quote from Akim Demaille in the Help

Bison list 2002/01/17:

*>>>>*

This is not absolutely true, although it is in practice. IIRC the

result holds when there are no empty rules. See for instance

http://compilers.iecc.com/comparch/article/93-09-025

or the errata of Andrew Appel about this book on compiler

implementation:

http://www.cs.princeton.edu/~appel/modern/basic/ml/errata.html

Page 64. Figure 3.26 incorrectly shows LL(1) as a subset of

SLR. In fact, LL(1) is not even a subset of LALR(1): there is

an LL(1) grammar that is not LALR(1).

<<<<

Hans Aberg * Anti-spam: remove "remove." from email address.

* Email: Hans Aberg <remove.haberg@member.ams.org>

* Home Page: <http://www.math.su.se/~haberg/>

* AMS member listing: <http://www.ams.org/cml/>

[Oh, right. Oops. -John]

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