0003787: camlp4 removes empty precedence levels on delete_rule

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0003787

OCaml

Camlp4

public

2005-09-12 11:26

2012-09-11 10:27

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administrator

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Priority

normal

Severity

minor

Reproducibility

always

Status

resolved

Resolution

suspended

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Target Version

4.00.1+dev

Fixed in Version

Summary

0003787: camlp4 removes empty precedence levels on delete_rule

Description

Full_Name: Stefano Zacchiroli
Version: 3.08.3
OS: GNU/Linux
Submission from: tsunami.mowgli.cs.unibo.it (130.136.129.199)

The camlp4 API permits, via "Grammar.extend" to create empty precedence level.
This is usefule since you can assign names to them and make assumptions on their
relative order in future extensions of the grammar.

If an empty level gets extended with a rule, the obtained level then contains
only one rule. When that rule is removed using "Gramext.delete_rule" the entire
precedence level is removed, making further extension of it failing with
something like:

No level labelled "10N" in entry "term"
Fatal error: exception Failure("Grammar.extend")

A work-around is to never have empty precedence level, always filling them with
a production on dummy tokens which are never generated by the lexer, ... but is
really a ugly hack.

TIA,
Cheers.

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Notes
(0008059) doligez (manager) 2012-09-11 10:27	This is about the old camlp4, which now lives as camlp5, and is not part of the core OCaml distribution.

Issue History
Date Modified	Username	Field	Change
2005-11-18 10:14	administrator	New Issue
2008-10-05 19:06	ertai	Category	OCaml general => Camlp4
2008-10-05 19:06	ertai	Description Updated
2012-07-11 17:03	doligez	Target Version	=> 4.01.0+dev
2012-07-11 17:03	doligez	Note Deleted: 0003040
2012-07-31 13:37	doligez	Target Version	4.01.0+dev => 4.00.1+dev
2012-09-11 10:27	doligez	Note Added: 0008059
2012-09-11 10:27	doligez	Status	acknowledged => resolved
2012-09-11 10:27	doligez	Resolution	open => suspended