Hpath

This code is heavy work in progress and does not work today. The examples and usage hints given below only show the goals.

Installation

Add this line to your application's Gemfile:

gem 'hpath'

And then execute:

$ bundle

Or install it yourself as:

$ gem install hpath

Usage

Here are some examples of hpath in action.

record = {
  title: "About a hash",
  creator: [
    "Hashman",
    "Hashboy"
  ],
  price: [
    { currency: :USD, value: 12.99 },
    { currency: :EUR, value:  8.99 }
  ],
  subject: [
    { type: "automatic", value: "hash" },
    { type: "automatic", value: "hashes" },
    { type: "automatic", value: "ruby" },
    { type: "manual", value: "hash" },
    { type: "manual", value: "array" },
    { type: "manual", value: "Hashman" },
    { type: "manual", value: "Hashboy" },
  ],
  _source: {
    "id" => "123",
    "title" => "<h1>About a hash</h1>",
    ...
  }
}

Hpath.get record, "/title"
# => "About a hash"

Hpath.get record, "/_source/id"
# => "123"

Hpath.get record, "/_source/[id, title]"
# => { "id" => "123", "title" => "<h1>About a hash</h1>" }

Hpath.get record, "/price/*[currency=USD]"
# => [{ currency: :USD, value: 12.99 }]

Hpath.get record, "/price/*[currency=USD,value<10]"
# => nil

Hpath.get record, "/price/*[(currency=USD|currency=EUR),value<10]"
# => [{ currency: :EUR, value:  8.99 }]

Hpath.get record, "/subject/*[type=automatic]"
# => [
#      { type: "automatic", value: "hash" },
#      { type: "automatic", value: "hashes" },
#      { type: "automatic", value: "ruby" }
#    ]

Hpath.get record, "/subject/*[type=automatic]/type"
# => ["automatic", "automatic", "automatic"]

Syntax

/

Get the root element.

Hpath.get [:a,:b,:c], "/"
# => [:a,:b,:c]

/[n]

Get the n-th element of an array.

Hpath.get [:a,:b,:c], "/[1]"
# => :a

/[n,m,...]

Get the n-th, m-th and ... element of an array.

Hpath.get [:a,:b,:c], "/[1,2]"
# => [:a,:b]

/[key1, key2, ...]

If current element is a hash, get a hash only with the given keys. Since it cannot be determined, if the key is a symbol or a string, both interpretations are checked. If the current object is not a hash, but has methods named key1, key2, this methods are called and the results are returned.

Hpath.get {a: "b", c: "d", e: "f"}, "/[a,c]"
# => {a: "b", c: "d"}

/*

Get all elements of the current root element. If it's a array, this simply returns the array. If it's a hash, an array of all key/value pairs is returned.

Hpath.get [:a,:b,:c], "/*"
# => [:a,:b,:c]

Hpath.get {a: "b", c: "d", e: "f"}, "/*"
# => [{a: "b"}, {c: "d"}, {e: "f"}]

/key

If the current element is a hash, return the value of the given key. If the current element is not a hash, but has a method named key, this method is called and the result is returned.

Hpath.get {a: { b: "c" } }, "/a"
# => { b: "c" }

If the current element is an array, the non-array behaviour is applied to all members of the array.

Hpath.get([{a:"1", b:"2", c:"3"}, {a:"2", b:"5", c:"6"}], "/a")
# => ["1", "2"]

Contributing

1. Fork it ( http://github.com//hpath/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request