Re: Java Comment-Preserving Grammar

Alex Colvin <alexc@std.com>
13 Jun 2004 11:18:20 -0400

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[4 earlier articles]
Re: Java Comment-Preserving Grammar dobes@dobesland.com (Dobes Vandermeer) (2004-05-30)
Re: Java Comment-Preserving Grammar tbauer@cadrc.calpoly.edu (Tim Bauer) (2004-05-30)
Re: Java Comment-Preserving Grammar jens.troeger@light-speed.de (2004-06-06)
Re: Java Comment-Preserving Grammar clint@0lsen.net (Clint Olsen) (2004-06-06)
Re: Java Comment-Preserving Grammar gah@ugcs.caltech.edu (glen herrmannsfeldt) (2004-06-09)
Re: Java Comment-Preserving Grammar cfc@shell01.TheWorld.com (Chris F Clark) (2004-06-11)
Re: Java Comment-Preserving Grammar alexc@std.com (Alex Colvin) (2004-06-13)
Re: Java Comment-Preserving Grammar gah@ugcs.caltech.edu (glen herrmannsfeldt) (2004-06-13)
Re: Java Comment-Preserving Grammar cfc@shell01.TheWorld.com (Chris F Clark) (2004-06-15)
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From: Alex Colvin <alexc@std.com>
Newsgroups: comp.compilers
Date: 13 Jun 2004 11:18:20 -0400
Organization: The World : www.TheWorld.com : Since 1989
References: 04-05-075 04-06-004 04-06-022 04-06-041
Keywords: Java, parse
Posted-Date: 13 Jun 2004 11:18:20 EDT

>> Scanner Usually Skips Over Comments In The Source Code Already,
>> Such That The Parser Doesn'T Even See Them. However, You Can Write
>> Your Own Scanner And Parser, That Make Comments Explicit In The Grammer.
>> But If You Want To Allow Comments _Anywhere_ In Yout Language, The
>> Good Luck!! :-) That Grammar Is Going To Be A Mess....


>> Would it be that hard? Most languages that I know
>> of allow comments in places where blank space is allowed.


Many languages allow space/comments between any adjacent tokens. In such
cases, you could replace every <token> in the grammar with
<token><whitespace/comment?> (with some extra cruft at the start).


But this (regular) behavior is can also be captured in the lexer by
associating the whitespace/comment to the preceding token. Or maybe the
following.


--
mac the naf


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