Class: Hotdog::Expression::FuncallNode

Inherits:
ExpressionNode show all
Defined in:
lib/hotdog/expression/semantics.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(function, args) ⇒ FuncallNode

Returns a new instance of FuncallNode.



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# File 'lib/hotdog/expression/semantics.rb', line 415

def initialize(function, args)
  # FIXME: smart argument handling (e.g. arity & type checking)
  case function.to_s
  when "HEAD", "head"
    @function = :HEAD
  when "GROUP_BY", "group_by"
    @function = :GROUP_BY
  when "LIMIT", "limit"
    @function = :HEAD
  when "ORDER_BY", "order_by"
    @function = :ORDER_BY
  when "REVERSE", "reverse"
    @function = :REVERSE
  when "SAMPLE", "sample"
    @function = :HEAD
    args[0] = FuncallNode.new("SHUFFLE", [args[0]])
  when "SHUFFLE", "shuffle"
    @function = :SHUFFLE
  when "SLICE", "slice"
    @function = :SLICE
  when "SORT", "sort"
    @function = :ORDER_BY
  when "TAIL", "tail"
    @function = :TAIL
  else
    raise(SyntaxError.new("unknown function call: #{function}"))
  end
  @args = args
end

Instance Attribute Details

#args ⇒ Object (readonly)

Returns the value of attribute args.



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# File 'lib/hotdog/expression/semantics.rb', line 413

def args
  @args
end

#function ⇒ Object (readonly)

Returns the value of attribute function.



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# File 'lib/hotdog/expression/semantics.rb', line 413

def function
  @function
end

Instance Method Details

#dump(options = {}) ⇒ Object 



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# File 'lib/hotdog/expression/semantics.rb', line 445

def dump(options={})
  args = @args.map { |arg|
    if ExpressionNode === arg
      arg.dump(options)
    else
      arg
    end
  }
  {funcall: @function.to_s, args: args}
end

#evaluate(environment, options = {}) ⇒ Object 



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# File 'lib/hotdog/expression/semantics.rb', line 490

def evaluate(environment, options={})
  case function
  when :HEAD
    args[0].evaluate(environment, options).take(args[1] || 1)
  when :GROUP_BY
    intermediate = args[0].evaluate(environment, options)
    q = "SELECT DISTINCT hosts_tags.host_id FROM hosts_tags " \
          "INNER JOIN tags ON hosts_tags.tag_id = tags.id " \
          "WHERE tags.name = ? AND hosts_tags.host_id IN (%s) " \
          "GROUP BY tags.value;" % intermediate.map { "?" }.join(", ")
    QueryExpressionNode.new(q, [args[1]] + intermediate, fallback: nil).evaluate(environment, options)
  when :ORDER_BY
    intermediate = args[0].evaluate(environment, options)
    if args[1]
      q = "SELECT DISTINCT hosts_tags.host_id FROM hosts_tags " \
            "INNER JOIN tags ON hosts_tags.tag_id = tags.id " \
            "WHERE tags.name = ? AND hosts_tags.host_id IN (%s) " \
            "ORDER BY tags.value;" % intermediate.map { "?" }.join(", ")
      QueryExpressionNode.new(q, [args[1]] + intermediate, fallback: nil).evaluate(environment, options)
    else
      q = "SELECT DISTINCT hosts_tags.host_id FROM hosts_tags " \
            "INNER JOIN tags ON hosts_tags.tag_id = tags.id " \
            "WHERE hosts_tags.host_id IN (%s) " \
            "ORDER BY hosts_tags.host_id;" % intermediate.map { "?" }.join(", ")
      QueryExpressionNode.new(q, intermediate, fallback: nil).evaluate(environment, options)
    end
  when :REVERSE
    args[0].evaluate(environment, options).reverse()
  when :SHUFFLE
    args[0].evaluate(environment, options).shuffle()
  when :SLICE
    args[0].evaluate(environment, options).slice(args[1], args[2] || 1)
  when :TAIL
    args[0].evaluate(environment, options).last(args[1] || 1)
  else
    []
  end
end

#optimize(options = {}) ⇒ Object 



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# File 'lib/hotdog/expression/semantics.rb', line 456

def optimize(options={})
  case function
  when :HEAD
    @args[0] = @args[0].optimize(options)
  when :GROUP_BY
    @args[0] = @args[0].optimize(options)
    if TagExpressionNode === args[1]
      # workaround for expressions like `ORDER_BY((environment:development),role)`
      @args[1] = @args[1].tag_name
    else
      @args[1] = @args[1]
    end
  when :ORDER_BY
    @args[0] = @args[0].optimize(options)
    if @args[1]
      if TagExpressionNode === @args[1]
        # workaround for expressions like `ORDER_BY((environment:development),role)`
        @args[1] = @args[1].tag_name
      else
        @args[1] = @args[1]
      end
    end
  when :REVERSE
    @args[0] = @args[0].optimize(options)
  when :SHUFFLE
    @args[0] = @args[0].optimize(options)
  when :SLICE
    @args[0] = @args[0].optimize(options)
  when :TAIL
    @args[0] = @args[0].optimize(options)
  end
  self
end