6 Aug 2001 04:04:57 -0400

Related articles |
---|

Simple Expression Recursion vs Expression/Term/Factor stoggers@uniquest.demon.co.uk (Mike Stogden) (2001-08-02) |

Re: Simple Expression Recursion vs Expression/Term/Factor Mark.van.den.Brand@cwi.nl (M.G.J. van den Brand) (2001-08-06) |

Re: Simple Expression Recursion vs Expression/Term/Factor lucadesantis@infinito.it (luca) (2001-08-06) |

Re: Simple Expression Recursion vs Expression/Term/Factor gregod@cs.rpi.edu (Douglas Gregor) (2001-08-06) |

Re: Simple Expression Recursion vs Expression/Term/Factor joachim_d@gmx.de (Joachim Durchholz) (2001-08-08) |

Re: Simple Expression Recursion vs Expression/Term/Factor lucads@xoommail.xoom.it (Luca) (2001-08-08) |

Re: Simple Expression Recursion vs Expression/Term/Factor andi@diagonal.ch (Andreas Gieriet) (2001-08-15) |

From: | "luca" <lucadesantis@infinito.it> |

Newsgroups: | comp.compilers |

Date: | 6 Aug 2001 04:04:57 -0400 |

Organization: | Micron Technology, Inc. |

References: | 01-08-016 |

Keywords: | parse |

Posted-Date: | 06 Aug 2001 04:04:56 EDT |

Mike Stogden wrote in message 01-08-016...

*>I have seen expressions for the same language described as...*

*>*

*>expr -> expr + expr*

*>expr -> expr * expr*

*>etc...*

*>*

*>alternatively...*

*>*

*>expr -> expr + term*

*>term -> factor | term * factor*

*>factor -> number | identifier*

*>etc...*

*>*

I think the second approach allows to manage priority of operations is a

simpler way.

Using the form Espression/Term/Factor , the syntax tree obtained has

implicit informations about priority of multiplication respect to addition.

In other words: precedence of multiplication is reflected in the structure

of syntax tree obtained after parsing. In the first approach you must add

code to the compiler to check priority, you need to process syntax tree to

compute expressions.

bye

Luca De Santis

http://members.xoom.it/lucads

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