XSLT-like search in a Ruby Hash

ruby-talk
1

I have a need for some relatively fancy searching in a hash, and I am
wondering if there's anything that does some kind of pattern matching on
Hash contents.

Specifically here's an example of what I would like to be able to write:
http://www.pastie.org/1127920

Yes, I can write the iterators, collects, merges and what else, but
nicer would be some kind of structured query syntax. Any ideas?

Thanks!

Pito

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Posted via http://www.ruby-forum.com/.

2

Might be something useful here:

http://eigenclass.org/hiki/Pattern+matching+over+Ruby+objects

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On 08/30/2010 05:29 PM, Pito Salas wrote:

I have a need for some relatively fancy searching in a hash, and I am
wondering if there's anything that does some kind of pattern matching on
Hash contents.

Specifically here's an example of what I would like to be able to write:
http://www.pastie.org/1127920

Yes, I can write the iterators, collects, merges and what else, but
nicer would be some kind of structured query syntax. Any ideas?

Thanks!

Pito

3

For the simple case one could do

class Hash
  def nested_value? *keys, val
    val.eql?( keys.inject(self) {|h,k| h.fetch(k) { return false } } )
rescue return false
  end

  def nested_key? *keys
    keys.inject(self) {|h,k| h.fetch(k) { return false } } rescue return false
    true
  end
end

Note, you need 1.9* for this - otherwise you need to manually
distribute arguments.

Kind regards

robert

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2010/8/31 Pito Salas <rps@salas.com>:

I have a need for some relatively fancy searching in a hash, and I am
wondering if there's anything that does some kind of pattern matching on
Hash contents.

Specifically here's an example of what I would like to be able to write:
http://www.pastie.org/1127920

Yes, I can write the iterators, collects, merges and what else, but
nicer would be some kind of structured query syntax. Any ideas?

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/