Module: Puppet::Pops::Lookup

Defined in:
lib/puppet/pops/lookup.rb,
lib/puppet/pops/lookup/explainer.rb,
lib/puppet/pops/lookup/invocation.rb

Overview

This class is the backing implementation of the Puppet function ‘lookup’. See puppet/functions/lookup.rb for documentation.

Defined Under Namespace

Classes: ExplainDataProvider, ExplainGlobal, ExplainInterpolate, ExplainMerge, ExplainModule, ExplainNode, ExplainPath, ExplainScope, ExplainTreeNode, Explainer, Invocation

Class Method Summary collapse

Class Method Details

.lookup(name, value_type, default_value, has_default, merge, lookup_invocation) ⇒ Object

Performs a lookup in the configured scopes and optionally merges the default.

This is a backing function and all parameters are assumed to have been type checked. See puppet/functions/lookup.rb for full documentation and all parameter combinations.

Parameters:

  • name (String|Array<String>) —

    The name or names to lookup

  • type (Puppet::Pops::Types::PAnyType|nil) —

    The expected type of the found value

  • default_value (Object) —

    The value to use as default when no value is found

  • has_default (Boolean) —

    Set to true if default_value is included (nil is a valid default_value)

  • merge (Puppet::Pops::MergeStrategy, String, Hash<String,Object>, nil) —

    Merge strategy or hash with strategy and options

  • lookup_invocation (Puppet::Pops::Lookup::Invocation) —

    Invocation data containing scope, overrides, and defaults

Returns:

  • (Object) —

    The found value



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# File 'lib/puppet/pops/lookup.rb', line 18

def self.lookup(name, value_type, default_value, has_default, merge, lookup_invocation)
  value_type = Puppet::Pops::Types::PDataType::DEFAULT if value_type.nil?
  names = name.is_a?(Array) ? name : [name]

  # find first name that yields a non-nil result and wrap it in a two element array
  # with name and value.
  not_found = Puppet::Pops::MergeStrategy::NOT_FOUND
  override_values = lookup_invocation.override_values
  result_with_name = names.reduce([nil, not_found]) do |memo, key|
    value = override_values.include?(key) ? assert_type('override', value_type, override_values[key]) : not_found
    catch(:no_such_key) { value = search_and_merge(key, lookup_invocation, merge) } if value.equal?(not_found)
    break [key, assert_type('found', value_type, value)] unless value.equal?(not_found)
    memo
  end

  # Use the 'default_values' hash as a last resort if nothing is found
  if result_with_name[1].equal?(not_found)
    default_values = lookup_invocation.default_values
    unless default_values.empty?
      result_with_name = names.reduce(result_with_name) do |memo, key|
        value = default_values.include?(key) ? assert_type('default_values_hash', value_type, default_values[key]) : not_found
        memo = [key, value]
        break memo unless value.equal?(not_found)
        memo
      end
    end
  end

  answer = result_with_name[1]
  if answer.equal?(not_found)
    if block_given?
      answer = assert_type('default_block', value_type, yield(name))
    elsif has_default
      answer = assert_type('default_value', value_type, default_value)
    else
      fail_lookup(names)
    end
  end
  answer
end

.search_and_merge(name, lookup_invocation, merge) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/puppet/pops/lookup.rb', line 60

def self.search_and_merge(name, lookup_invocation, merge)
  return Puppet::DataProviders.lookup_adapter(lookup_invocation).lookup(name, lookup_invocation, merge)
end