Class: Dentaku::AST::Reduce

Inherits:
Function show all
Defined in:
lib/dentaku/ast/functions/reduce.rb

Constant Summary

Constants inherited from Function

Function::DIG

Instance Attribute Summary

Attributes inherited from Function

#args

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Function

#accept, get, numeric, register, register_class, registry

Methods inherited from Node

arity, #name, precedence, resolve_class, #type

Constructor Details

#initialize(*args) ⇒ Reduce

Returns a new instance of Reduce.



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# File 'lib/dentaku/ast/functions/reduce.rb', line 15

def initialize(*args)
  super

  validate_identifier(@args[1], 'second')
  validate_identifier(@args[2], 'third')
end

Class Method Details

.max_param_count ⇒ Object 



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# File 'lib/dentaku/ast/functions/reduce.rb', line 11

def self.max_param_count
  5
end

.min_param_count ⇒ Object 



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# File 'lib/dentaku/ast/functions/reduce.rb', line 7

def self.min_param_count
  4
end

Instance Method Details

#dependencies(context = {}) ⇒ Object 



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# File 'lib/dentaku/ast/functions/reduce.rb', line 22

def dependencies(context = {})
  collection      = @args[0]
  memo_identifier = @args[1].identifier
  item_identifier = @args[2].identifier
  expression      = @args[3]

  collection_deps = collection.dependencies(context)
  expression_deps = expression.dependencies(context).reject do |i|
    i == memo_identifier || i.start_with?("#{memo_identifier}.") ||
    i == item_identifier || i.start_with?("#{item_identifier}.")
  end
  inital_value_deps = @args[4] ? @args[4].dependencies(context) : []

  collection_deps + expression_deps + inital_value_deps
end

#validate_identifier(arg, position, message = "#{name}() requires #{position} argument to be an identifier") ⇒ Object

Raises:



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# File 'lib/dentaku/ast/functions/reduce.rb', line 54

def validate_identifier(arg, position, message = "#{name}() requires #{position} argument to be an identifier")
  raise ParseError.for(:node_invalid), message unless arg.is_a?(Identifier)
end

#value(context = {}) ⇒ Object 



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# File 'lib/dentaku/ast/functions/reduce.rb', line 38

def value(context = {})
  collection      = Array(@args[0].value(context))
  memo_identifier = @args[1].identifier
  item_identifier = @args[2].identifier
  expression      = @args[3]
  initial_value   = @args[4] && @args[4].value(context)

  collection.reduce(initial_value) do |memo, item|
    expression.value(
      context.merge(
        FlatHash.from_hash_with_intermediates(memo_identifier => memo, item_identifier => item)
      )
    )
  end
end