Class: ObjectTemplate

Inherits:
Object
  • Object
show all
Defined in:
lib/object-template.rb

Overview

Base class for classes of templates used to match somewhat arbitrary objects.

Direct Known Subclasses

PortableObjectTemplate, RubyObjectTemplate

Defined Under Namespace

Classes: MemberMatchingSet

Constant Summary collapse

VERSION = 
"0.8"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(spec, key_converter = nil) ⇒ ObjectTemplate

The key_converter is for matching objects that, for example, have had symbol keys serialized to strings. Using a converter that round-trips through the same serializer, symbols in keys will match strings. However, symbols in values will not.



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# File 'lib/object-template.rb', line 20

def initialize spec, key_converter = nil
  unless spec.respond_to? :size and spec.respond_to? :each
    raise ArgumentError, "cannot be used as a template: #{spec.inspect}"
  end

  @spec = spec
  @size = spec.size
  @key_converter = key_converter
  @matchers = []
  
  if spec.respond_to? :to_hash # assume hash-like
    @shibboleth = :to_hash
    spec.each do |k, v|
      if key_converter
        k = key_converter[k => nil].keys[0]
        # Note: the [k=>nil].keys[0] is needed instead of just [k]
        # because the key_converter might not convert values, only keys.
        # We do not assume that k is a scalar.
      end
      fill_matchers k, v
    end

  else # assume array-like
    @shibboleth = :to_ary
    spec.each_with_index do |v, i|
      fill_matchers i, v unless v.nil?
    end
  end
end

Instance Attribute Details

#key_converter ⇒ Object (readonly)

Returns the value of attribute key_converter.



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# File 'lib/object-template.rb', line 7

def key_converter
  @key_converter
end

#spec ⇒ Object (readonly)

Returns the value of attribute spec.



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# File 'lib/object-template.rb', line 7

def spec
  @spec
end

Instance Method Details

#===(obj) ⇒ Object

True if the template matches the given object. Adapted from rinda/rinda.rb.



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# File 'lib/object-template.rb', line 70

def === obj
  return false unless obj.respond_to?(@shibboleth)
  return false unless @size == obj.size
  @matchers.each do |k, v|
    begin
      it = obj.fetch(k)
    rescue
      return false
    end
    next if v.nil?
    next if v == it
    next if v === it
    return false
  end
  return true
end

#inspect ⇒ Object 



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# File 'lib/object-template.rb', line 87

def inspect
  "<#{self.class}: #{@spec}>"
end

#optimize! ⇒ Object

Reorders the list of matchers so that easy ones come first. For example: nil, then single values (==), then patterns (===). Returns self.



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# File 'lib/object-template.rb', line 53

def optimize!
  @matchers.sort_by! do |k, v|
    case v
    when nil;               0
    when Range;             2
    when Module;            3
    when Regexp;            4
    when MemberMatchingSet; 4
    when Proc;              5
    else                    1 # assume it is a value
    end
  end
  self
end