Module: Dogfood::DSL::Evaluator

Defined in:
lib/dogfood/dsl/evaluator.rb

Overview

Evaluates minimal $... expressions. Safe: it is a tiny hand-rolled recursive-descent parser, NOT eval. See SPEC.md 4.4 for the grammar.

Defined Under Namespace

Classes: Parser

Constant Summary collapse

TOKEN = 
/\$\{([^}]*)\}/

Class Method Summary collapse

Class Method Details

.eval(value, bindings:, state:, rng:, self_object: nil) ⇒ Object

Evaluates a value that may contain $... tokens. Returns the raw bound value if the entire input is a single $...; otherwise interpolates tokens into the surrounding string.



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# File 'lib/dogfood/dsl/evaluator.rb', line 13

def self.eval(value, bindings:, state:, rng:, self_object: nil)
  if value.is_a?(String) && (m = TOKEN.match(value)) && m[0] == value
    return evaluate_expression(m[1], bindings: bindings, state: state, rng: rng, self_object: self_object)
  end

  case value
  when String
    value.gsub(TOKEN) do
      result = evaluate_expression(Regexp.last_match(1), bindings: bindings, state: state, rng: rng, self_object: self_object)
      stringify(result)
    end
  when Hash
    value.each_with_object({}) do |(k, v), acc|
      acc[eval(k, bindings: bindings, state: state, rng: rng, self_object: self_object)] =
        eval(v, bindings: bindings, state: state, rng: rng, self_object: self_object)
    end
  when Array
    value.map { |v| eval(v, bindings: bindings, state: state, rng: rng, self_object: self_object) }
  else
    value
  end
end

.evaluate_expression(expr, bindings:, state:, rng:, self_object: nil) ⇒ Object

Parses and evaluates a single expression (without $... delimiters).



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# File 'lib/dogfood/dsl/evaluator.rb', line 37

def self.evaluate_expression(expr, bindings:, state:, rng:, self_object: nil)
  Parser.new(expr, bindings: bindings, state: state, rng: rng, self_object: self_object).parse
end

.stringify(value) ⇒ Object 



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# File 'lib/dogfood/dsl/evaluator.rb', line 41

def self.stringify(value)
  case value
  when nil then "null"
  when true then "true"
  when false then "false"
  else value.to_s
  end
end