Sun, 24 May 1992 00:36:46 GMT

Related articles |
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Hybrid LR and LL parser tools? brueni@csgrad.cs.vt.edu (Dennis Brueni) (1992-05-20) |

Parsing Roman numbers joe@erix.ericsson.se (1992-05-22) |

Re: Parsing Roman numbers byron@archone.tamu.edu (1992-05-23) |

Re: Parsing Roman numbers henry@zoo.toronto.edu (1992-05-24) |

Re: Parsing Roman numbers weberwu@inf.fu-berlin.de (1992-05-24) |

Re: Parsing Roman numbers Martin.Ward@durham.ac.uk (Martin Ward) (1992-05-26) |

Newsgroups: | comp.compilers |

From: | henry@zoo.toronto.edu (Henry Spencer) |

Keywords: | parse |

Organization: | U of Toronto Zoology |

References: | 92-05-119 92-05-126 |

Date: | Sun, 24 May 1992 00:36:46 GMT |

joe@erix.ericsson.se (Joe Armstrong) writes:

*>Has anybody got a grammar (preferably yacc) for parsing roman numbers?*

I don't understand why you need a parser for this. Roman numerals are

described by the regular expression

M*(CM|DC{0,3}|CD|C{0,3})(XC|LX{0,3}|XL|X{0,3})(IX|VI{0,3}|IV|I{0,3})

(using POSIX 1003.2 regular-expression notation) unless you want to write

in a requirement that they be non-null, which would take a slightly more

complex form to deal with the requirement that at least one of the parts

be non-empty. Variations in notation, like allowing VIIII (which was

legitimate Roman practice at one time) are trivial to accommodate.

*>Are they LL(k) LR(k) or what?*

Since they can be described by a regular expression, they can be parsed

by a regular grammar, which is a still more restricted form. So the

answer is "all of the above".

--

Henry Spencer @ U of Toronto Zoology, henry@zoo.toronto.edu utzoo!henry

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