Module: Peruby::Interpolation

Defined in:
lib/peruby/runtime/interpolation.rb

Overview

Expands the escape and variable forms needed by interpolating strings.

Constant Summary collapse

ESCAPED_DOLLAR = 
"\u0000DOLLAR\u0000"
ESCAPED_ARRAY = 
"\u0000ARRAY\u0000"
ESCAPED_BACKSLASH = 
"\u0000BACKSLASH\u0000"
NAME = 
/[A-Za-z_]\w*(?:(?:::|')[A-Za-z_]\w*)*/
ESCAPES = 
{ 'n' => "\n", 't' => "\t", 'r' => "\r", 'f' => "\f", 'b' => "\b",
'a' => "\a", 'e' => "\e", '\\' => '\\', '"' => '"', '$' => '$', '@' => '@' }.freeze

Class Method Summary collapse

Class Method Details

.array_last(source, index, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 122

def array_last(source, index, env)
  name = source[(index + 2)..].match(/\A(#{NAME.source})/)&.[](1)
  return [nil, nil] unless name

  [name.length + 2, (env.fetch(:array, name).size - 1).to_s]
end

.balanced_finish(source, start) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 150

def balanced_finish(source, start)
  pairs = { '{' => '}', '[' => ']' }
  close = pairs[source[start]]
  return unless close

  depth = 1
  index = start + 1
  while index < source.length
    depth += 1 if source[index] == source[start]
    depth -= 1 if source[index] == close
    return index + 1 if depth.zero?

    index += source[index] == '\\' ? 2 : 1
  end
end

.braced_interpolation(source, index, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 108

def braced_interpolation(source, index, env)
  finish = balanced_finish(source, index + 1)
  return [nil, nil] unless finish

  body = source[(index + 2)...(finish - 1)].strip
  marker = source[index]
  value = if marker == '$' && body.match?(/\A#{NAME.source}\z/)
            env.fetch(:scalar, body).get
          else
            dereferenced(evaluate(body, env, :scalar), marker)
          end
  [finish - index, stringify(value, marker, env)]
end

.cases(text) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 192

def cases(text)
  output = +''
  mode = nil
  quote = false
  once = nil
  index = 0
  while index < text.length
    control = text[index, 2]
    if control.match?(/\A\\[ULQulE]\z/)
      command = control[1]
      mode = command if %w[U L].include?(command)
      quote = true if command == 'Q'
      once = command if %w[u l].include?(command)
      if command == 'E'
        mode = once = nil
        quote = false
      end
      index += 2
      next
    end

    character = text[index]
    character = mode == 'U' ? character.upcase : character.downcase if mode
    character = once == 'u' ? character.upcase : character.downcase if once
    once = nil
    output << (quote ? Regexp.escape(character) : character)
    index += 1
  end
  output
end

.consume_access_chain(source, index) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 136

def consume_access_chain(source, index)
  loop do
    start = if source[index, 2] == '->' && source[index + 2] && '[{'.include?(source[index + 2])
              index + 2
            elsif source[index] && '[{'.include?(source[index])
              index
            end
    break unless start

    index = balanced_finish(source, start) || index
  end
  index
end

.dereferenced(value, marker) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 171

def dereferenced(value, marker)
  return value unless value.is_a?(Ref)
  return value.target.get if marker == '$' && value.target.is_a?(Scalar)
  return value.target.list if marker == '@' && value.target.is_a?(PerlArray)

  value
end

.escape_match(match) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 43

def escape_match(match)
  return match[1].to_i(16).chr(Encoding::UTF_8) if match[1]
  return match[2].to_i(16).chr(Encoding::UTF_8) if match[2]
  return match[3].to_i(8).chr if match[3]
  return (match[4].ord & 31).chr if match[4]
  return match[5].to_i(16).chr(Encoding::UTF_8) if match[5]

  return "\\#{match[6]}" if %w[U L Q u l E].include?(match[6])

  ESCAPES.fetch(match[6], match[6])
end

.escapes(text) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 37

def escapes(text)
  text.gsub(/\\(?:x\{([0-9a-fA-F]+)\}|x([0-9a-fA-F]{1,2})|0([0-7]{0,2})|c(.)|N\{U\+([0-9a-fA-F]+)\}|(.))/) do
    escape_match(Regexp.last_match)
  end
end

.evaluate(source, env, context) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 166

def evaluate(source, env, context)
  tree = Parser.parse("#{source};", file: env.runtime.current_file, package: env.package)
  Compiler.new.compile(tree).run(env, context)
end

.expand(quote, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 15

def expand(quote, env)
  raw = quote.parts.first
  return escapes(raw) unless quote.interpolate

  text = interpolate_expressions(raw, env)
  cases(escapes(text)).gsub(ESCAPED_DOLLAR, '$').gsub(ESCAPED_ARRAY, '@').gsub(ESCAPED_BACKSLASH, '\\')
end

.interpolate(value, sigil, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 55

def interpolate(value, sigil, env)
  return Conv.to_str(value.get) if sigil == :scalar

  value.list.map { |cell| Conv.to_str(cell.get) }.join(Conv.to_str(env.fetch(:scalar, '"').get))
end

.interpolate_expressions(source, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 61

def interpolate_expressions(source, env)
  output = +''
  index = 0
  while index < source.length
    if source[index] == '\\'
      output << source[index, 2]
      index += 2
      next
    end
    unless '$@'.include?(source[index])
      output << source[index]
      index += 1
      next
    end

    length, value = interpolation_at(source, index, env)
    unless length
      output << source[index]
      index += 1
      next
    end
    output << protect(value)
    index += length
  end
  output
end

.interpolation_at(source, index, env) ⇒ Object

rubocop:disable-next Metrics/AbcSize



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# File 'lib/peruby/runtime/interpolation.rb', line 89

def interpolation_at(source, index, env)
  marker = source[index]
  return array_last(source, index, env) if marker == '$' && source[index + 1] == '#'
  return scalar_dereference(source, index, env) if marker == '$' && source[index + 1] == '$'
  return braced_interpolation(source, index, env) if source[index + 1] == '{'

  name = source[(index + 1)..].match(/\A(#{NAME.source}|\d+|[&`'+])/)&.[](1)
  return [nil, nil] unless name

  finish = consume_access_chain(source, index + 1 + name.length)
  expression = source[index...finish]
  value = if finish == index + 1 + name.length
            interpolate(env.fetch(marker == '$' ? :scalar : :array, name), marker == '$' ? :scalar : :array, env)
          else
            evaluate(expression, env, marker == '$' ? :scalar : :list)
          end
  [finish - index, stringify(value, marker, env)]
end

.pattern(quote, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 23

def pattern(quote, env)
  raw = quote.parts.first.gsub('\\$', ESCAPED_DOLLAR).gsub('\\@', ESCAPED_ARRAY)
  text = raw.gsub(variable_pattern) do
    sigil = Regexp.last_match(1) == '$' ? :scalar : :array
    name = Regexp.last_match(2) || Regexp.last_match(3)
    interpolate(env.fetch(sigil, name), sigil, env)
  end
  text.gsub(ESCAPED_DOLLAR, '\\$').gsub(ESCAPED_ARRAY, '\\@')
end

.protect(value) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 188

def protect(value)
  value.gsub('\\', ESCAPED_BACKSLASH).gsub('$', ESCAPED_DOLLAR).gsub('@', ESCAPED_ARRAY)
end

.scalar_dereference(source, index, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 129

def scalar_dereference(source, index, env)
  name = source[(index + 2)..].match(/\A(#{NAME.source})/)&.[](1)
  return [nil, nil] unless name

  [name.length + 2, Conv.to_str(dereferenced(env.fetch(:scalar, name).get, '$'))]
end

.stringify(value, marker, env) ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 179

def stringify(value, marker, env)
  if marker == '@'
    return Array(value).map { |item| Conv.to_str(item.respond_to?(:get) ? item.get : item) }
                       .join(Conv.to_str(env.fetch(:scalar, '"').get))
  end

  Conv.to_str(value.respond_to?(:get) ? value.get : value)
end

.variable_pattern ⇒ Object 



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# File 'lib/peruby/runtime/interpolation.rb', line 33

def variable_pattern
  /([$@])(?:\{(#{NAME.source})\}|(#{NAME.source}|\d+|[&`'+]))/
end