[Proj] proj.4 BNF
support.mn at elisanet.fi
support.mn at elisanet.fi
Mon Oct 20 22:45:50 EDT 2008
Frank Warmerdam <warmerdam at pobox.com> kirjoitti:
> support.mn at elisanet.fi wrote:
> > Maybe should define the correct BNF (BackusNaur Form) for proj.4?
> >
> > http://en.wikipedia.org/wiki/Backus-Naur_form
> >
> > That would help people to write correct proj.4 inits. I am still wondering
> > that if sombody enters wrong proj.4 attributes, the library takes them
> > in, but does
> > something else and never informs the user that something he was entering
> > was totally ignored. Not a very nice situation.
> >
> > There might be some kind of a stand alone pre scanner, that could be called
> > on demand and that checked the user entry and gave full information about
> > typos. errors and similar matters. It could be bypassed by those who do not
> > need it. But I don't see why anybody wanted to bypass checking of his
> > input.
>
> Janne,
>
> While this seems like a reasonable idea, I am doubtful that it will occur
> due to the challenges in implementing and keeping it up to date.
>
Well, I can start with it. Here is an example, maybe full of errors, but something
to start with.
------------------
<proj.4 definition> ::= <statement list>
<statement list> ::= <statement> {<SEP> <statement list> }
<statement> ::= <empty> | <comment line> | <assignment statement> | <identifier>
<empty ::=
<comment line> ::= # <anything but EOL> <EOL>
<assignment statement> ::= <identifier> = <right side>
<right side> ::= <identifier> | <identifier list> | <number> | <number list>
........
<EOL> ::= <CR> <LF> | <CR> | <LF>
<SEP> ::= <SPACE> | <TAB> | <EOL> | "+"
<SPACE> :: = " "
<TAB> ::= chr(09)
etc. etc.
regards: Janne.
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