22 Apr 2006 10:01:10 -0400

Related articles |
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understanding the intuition behind LL(k) parsers and LR(k) parsers Mark.Felzer@gmail.com (Mark F.) (2006-04-21) |

Re: understanding the intuition behind LL(k) parsers and LR(k) parsers tom@infoether.com (Tom Copeland) (2006-04-22) |

Re: understanding the intuition behind LL(k) parsers and LR(k) parsers cfc@shell01.TheWorld.com (Chris F Clark) (2006-04-23) |

Re: understanding the intuition behind LL(k) parsers and LR(k) parsers max@gustavus.edu (Max Hailperin) (2006-04-23) |

Re: understanding the intuition behind LL(k) parsers and LR(k) parsers DrDiettrich@compuserve.de (Hans-Peter Diettrich) (2006-04-23) |

Re: understanding the intuition behind LL(k) parsers and LR(k) parsers pbmann@gmail.com (2006-04-28) |

Re: understanding the intuition behind LL(k) parsers and LR(k) parsers pbmann@gmail.com (2006-05-01) |

From: | Tom Copeland <tom@infoether.com> |

Newsgroups: | comp.compilers |

Date: | 22 Apr 2006 10:01:10 -0400 |

Organization: | Compilers Central |

References: | 06-04-124 |

Keywords: | parse |

On Fri, 2006-04-21 at 23:47 -0400, Mark F. wrote:

*> .... A bottom up parser has to start with some kind of "last*

*> terminal" then build the tree in upward direction. Intuitively where*

*> would the bottom-up parser start if presented an input file. How*

*> does it find this starting point, of the parse. It has to be the*

*> deepest part of the tree. But how do you detect this, without*

*> expending the tree first from top-bottom? Is my thinking faulted?*

*> [Bottom up parsers use a state machine, like the one in a DFA regular*

*> expression matcher. The states implicitly encode all of the possible*

*> matches, and when the parser gets to a state where there's one complete*

*> match, you reduce the rule. -John]*

For notes on a particular implementation of a bottom up tree builder,

check out the JJTree documentation:

https://javacc.dev.java.net/doc/JJTree.html

It talks about ways to customize the node tree as it's constructed; lots

of good stuff there.

Yours,

tom

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