Class: Pray::Literal::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/pray/literal.rb

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/pray/literal.rb', line 179

def initialize(input)
  @input = input
  @cursor = 0
end

Instance Method Details

#finished? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pray/literal.rb', line 184

def finished? = @cursor >= @input.length

#identifier_continue?(character) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pray/literal.rb', line 377

def identifier_continue?(character)
  character.match?(%r{[[:alnum:]_\-.\\/]})
end

#identifier_start?(character) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pray/literal.rb', line 373

def identifier_start?(character)
  character && (character.match?(/[[:alpha:]]/) || character == "_")
end

#next_character ⇒ Object 



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# File 'lib/pray/literal.rb', line 195

def next_character
  character = peek
  @cursor += 1 if character
  character
end

#parse_array ⇒ Object 



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# File 'lib/pray/literal.rb', line 262

def parse_array
  next_character
  values = []
  loop do
    skip_whitespace
    break if peek == "]" && next_character

    values << parse_value
    skip_whitespace
    case peek
    when ","
      next_character
    when "]"
      next_character
      break
    else
      raise Error.parse("literal", "expected ',' or ']'")
    end
  end
  LiteralValue.new(kind: :array, value: values)
end

#parse_identifier ⇒ Object 



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# File 'lib/pray/literal.rb', line 345

def parse_identifier
  identifier = parse_identifier_name
  case identifier
  when "true" then LiteralValue.new(kind: :bool, value: true)
  when "false" then LiteralValue.new(kind: :bool, value: false)
  when "nil" then LiteralValue.new(kind: :null, value: nil)
  else LiteralValue.new(kind: :string, value: identifier)
  end
end

#parse_identifier_from(start) ⇒ Object 



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# File 'lib/pray/literal.rb', line 366

def parse_identifier_from(start)
  while peek && (identifier_continue?(peek) || peek == ".")
    next_character
  end
  LiteralValue.new(kind: :string, value: @input[start...@cursor])
end

#parse_identifier_name ⇒ Object 



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# File 'lib/pray/literal.rb', line 355

def parse_identifier_name
  raise Error.parse("literal", "expected identifier") unless identifier_start?(peek)

  start = @cursor
  next_character
  while peek && identifier_continue?(peek)
    next_character
  end
  @input[start...@cursor]
end

#parse_integer_or_identifier ⇒ Object 



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# File 'lib/pray/literal.rb', line 330

def parse_integer_or_identifier
  start = @cursor
  next_character if peek == "-"
  while peek&.match?(/[0-9_]/)
    next_character
  end
  if peek == "."
    return parse_identifier_from(start)
  end
  text = @input[start...@cursor].delete("_")
  LiteralValue.new(kind: :integer, value: Integer(text))
rescue ArgumentError => error
  raise Error.parse("literal", error.message)
end

#parse_map ⇒ Object 



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# File 'lib/pray/literal.rb', line 284

def parse_map
  next_character
  entries = {}
  loop do
    skip_whitespace
    break if peek == "}" && next_character

    key = parse_map_key
    skip_whitespace
    if remaining.start_with?("=>")
      @cursor += 2
    elsif peek == ":"
      next_character
    else
      raise Error.parse("literal", "expected ':' or '=>' after map key")
    end
    entries[key] = parse_value
    skip_whitespace
    case peek
    when ","
      next_character
    when "}"
      next_character
      break
    else
      raise Error.parse("literal", "expected ',' or '}'")
    end
  end
  LiteralValue.new(kind: :map, value: entries)
end

#parse_map_key ⇒ Object 



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# File 'lib/pray/literal.rb', line 315

def parse_map_key
  skip_whitespace
  case peek
  when '"', "'"
    value = parse_string
    value.value
  when ":"
    parse_symbol.value
  when "a".."z", "A".."Z", "_"
    parse_identifier_name
  else
    raise Error.parse("literal", "invalid map key")
  end
end

#parse_string ⇒ Object 



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# File 'lib/pray/literal.rb', line 221

def parse_string
  quote = next_character
  output = +""
  escaped = false
  while (character = next_character)
    if escaped
      output << case character
      when "n" then "\n"
      when "r" then "\r"
      when "t" then "\t"
      when "\\" then "\\"
      when "\"", "'" then character
      else character
      end
      escaped = false
      next
    end
    if character == "\\"
      escaped = true
      next
    end
    if character == quote
      return LiteralValue.new(kind: :string, value: output)
    end
    output << character
  end
  raise Error.parse("literal", "unterminated string literal")
end

#parse_symbol ⇒ Object 



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# File 'lib/pray/literal.rb', line 250

def parse_symbol
  next_character
  output = +""
  while (character = peek) && character.match?(%r{[[:alnum:]_\-.\\/]})
    output << character
    next_character
  end
  raise Error.parse("literal", "empty symbol") if output.empty?

  LiteralValue.new(kind: :symbol, value: output)
end

#parse_value ⇒ Object 



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# File 'lib/pray/literal.rb', line 201

def parse_value
  skip_whitespace
  case peek
  when '"', "'"
    parse_string
  when ":"
    parse_symbol
  when "["
    parse_array
  when "{"
    parse_map
  when "-", "0".."9"
    parse_integer_or_identifier
  when nil
    raise Error.parse("literal", "unexpected end of input")
  else
    parse_identifier
  end
end

#peek ⇒ Object 



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# File 'lib/pray/literal.rb', line 193

def peek = remaining[0]

#remaining ⇒ Object 



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# File 'lib/pray/literal.rb', line 185

def remaining = @input[@cursor..]

#skip_whitespace ⇒ Object 



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# File 'lib/pray/literal.rb', line 187

def skip_whitespace
  while (character = peek) && character.match?(/\s/)
    @cursor += 1
  end
end