Re^4: Parsing command string into a hash

I meant that i am finding it difficult to define the grammar for the parser .

Answering your queries :

> Why is a non-switch parameter called "param1' in one place and "value" in another.
- this was done to ease the effort i would have to put in the final command generation after the hash is built. All non-switch parameters within mandatory braces are put in the "mandatory hash" with keys as "param1,param2.....".
the switch parameters within mandatory braces are placed in a separate hash with the switch and corresponding parameter.

> Why would a property of mandatory parameters be called "param1"?
- "param1" is not a property of mandatory parameters ,but more of a key name to identify them.

> What if an alternation contains something other than just a <...> or just a <...>? For example, could you have { update | insert }? Your output format doesn't support that.
- For alternations , i place all the alternates in an anonymous array in the hash. A crude way of handling them but i''ve just about begun to build a prototype.

Comment on Re^4: Parsing command string into a hash

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Re^5: Parsing command string into a hash by ikegami (Patriarch) on Jul 17, 2009 at 13:37 UTC
this was done to ease the effort i would have to put in the final command generation after the hash is built. That makes no sense. Having the same data represented in two different ways doubles the effort rather than ease it. All non-switch parameters within mandatory braces are put in the "mandatory hash" with keys as "param1,param2....." In the desired output you posted, mandatory has an array for value, not a hash. "param1" is not a property of mandatory parameters, but more of a key name to identify them. Exactly, and that's wrong. It's redundant because it's already identified by its position in the array, and it's bad to use a hash as an array. This is how you'd ideally access the parameters: `for my $param (@$mandatory) { ... }` [download] This is what you'd need to do if you use a hash as an array: `sub sort_params { return map $_->[0], sort { $a->[1] <=> $b->[1] } map [ $_, /(\d+)/ ], @_; } for my $param_key (sort_params keys %$mandatory) { my $param = $mandatory->{$param_key}; ... }` [download] For alternations , i place all the alternates in an anonymous array in the hash. You have no way of identifying what's in the array, such as whether an element is a literal or a variable. That means you can't place all the alternates the array. You can only place the alternates that happen to be non-optional variable parameters.	[reply] [d/l] [select]

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Re^5: Parsing command string into a hash
by ikegami (Patriarch) on Jul 17, 2009 at 13:37 UTC

this was done to ease the effort i would have to put in the final command generation after the hash is built.

That makes no sense. Having the same data represented in two different ways doubles the effort rather than ease it.

All non-switch parameters within mandatory braces are put in the "mandatory hash" with keys as "param1,param2....."

In the desired output you posted, mandatory has an array for value, not a hash.

"param1" is not a property of mandatory parameters, but more of a key name to identify them.

Exactly, and that's wrong. It's redundant because it's already identified by its position in the array, and it's bad to use a hash as an array.

This is how you'd ideally access the parameters:

for my $param (@$mandatory) {
    ...
}
[download]

This is what you'd need to do if you use a hash as an array:

sub sort_params {
   return
       map $_->[0],
       sort { $a->[1] <=> $b->[1] }
       map [ $_, /(\d+)/ ],
       @_;
}

for my $param_key (sort_params keys %$mandatory) {
    my $param = $mandatory->{$param_key};
    ...
}
[download]

For alternations , i place all the alternates in an anonymous array in the hash.

You have no way of identifying what's in the array, such as whether an element is a literal or a variable. That means you can't place all the alternates the array. You can only place the alternates that happen to be non-optional variable parameters.

[reply]
[d/l]
[select]