class Pry::Indent

Pry::Indent is a class that can be used to indent a number of lines containing Ruby code similar as to how IRB does it (but better). The class works by tokenizing a string using CodeRay and then looping over those tokens. Based on the tokens in a line of code that line (or the next one) will be indented or un-indented by correctly.

Constants

IGNORE_TOKENS

Collection of token types that should be ignored. Without this list keywords such as “class” inside strings would cause the code to be indented incorrectly.

:pre_constant and :preserved_constant are the CodeRay 0.9.8 and 1.0.0 classifications of “true”, “false”, and “nil”.

MIDWAY_TOKENS

Collection of tokens that should appear dedented even though they don't affect the surrounding code.

OPEN_TOKENS

Hash containing all the tokens that should increase the indentation level. The keys of this hash are open tokens, the values the matching tokens that should prevent a line from being indented if they appear on the same line.

OPTIONAL_DO_TOKENS

Which tokens can be followed by an optional “do” keyword.

SINGLELINE_TOKENS

Which tokens can either be open tokens, or appear as modifiers on a single-line.

SPACES

The amount of spaces to insert for each indent level.

STATEMENT_END_TOKENS

Tokens that indicate the end of a statement (i.e. that, if they appear directly before an “if” indicates that that if applies to the same line, not the next line)

:reserved and :keywords are the CodeRay 0.9.8 and 1.0.0 respectively classifications of “super”, “next”, “return”, etc.

Attributes

indent_level[R]

@return [String] String containing the spaces to be inserted before the next line.

stack[R]

@return [Array<String>] The stack of open tokens.

Public Class Methods

indent(str) click to toggle source

Clean the indentation of a fragment of ruby.

@param [String] str @return [String]

# File lib/pry/indent.rb, line 82
def self.indent(str)
  new.indent(str)
end
nesting_at(str, line_number) click to toggle source

Get the module nesting at the given point in the given string.

NOTE If the line specified contains a method definition, then the nesting at the start of the method definition is used. Otherwise the nesting from the end of the line is used.

@param [String] str The ruby code to analyze @param [Fixnum] line_number The line number (starting from 1) @return [Array<String>]

# File lib/pry/indent.rb, line 95
def self.nesting_at(str, line_number)
  indent = new
  lines = str.split("\n")
  n = line_number - 1
  to_indent = lines[0...n] << (lines[n] || "").split("def").first(1)
  indent.indent(to_indent.join("\n") << "\n")
  indent.module_nesting
end
new(pry_instance = Pry.new) click to toggle source
# File lib/pry/indent.rb, line 104
def initialize(pry_instance = Pry.new)
  @pry_instance = pry_instance
  reset
end

Public Instance Methods

correct_indentation(prompt, code, overhang = 0) click to toggle source

Return a string which, when printed, will rewrite the previous line with the correct indentation. Mostly useful for fixing 'end'.

@param [String] prompt The user's prompt @param [String] code The code the user just typed in @param [Integer] overhang The number of characters to erase afterwards (the

the difference in length between the old line and the new one)

@return [String] correctly indented line

# File lib/pry/indent.rb, line 393
def correct_indentation(prompt, code, overhang = 0)
  prompt = prompt.delete("\001\002")
  line_to_measure = Pry::Helpers::Text.strip_color(prompt) << code
  whitespace = ' ' * overhang

  cols = @pry_instance.output.width
  lines = cols == 0 ? 1 : (line_to_measure.length / cols + 1).to_i

  if Helpers::Platform.windows_ansi?
    move_up = "\e[#{lines}F"
    move_down = "\e[#{lines}E"
  else
    move_up = "\e[#{lines}A\e[0G"
    move_down = "\e[#{lines}B\e[0G"
  end

  "#{move_up}#{prompt}#{colorize_code(code)}#{whitespace}#{move_down}"
end
current_prefix() click to toggle source

Get the indentation for the start of the next line.

This is what's used between the prompt and the cursor in pry.

@return String The correct number of spaces

# File lib/pry/indent.rb, line 181
def current_prefix
  in_string? ? '' : indent_level
end
end_of_statement?(last_token, last_kind) click to toggle source

If the code just before an “if” or “while” token on a line looks like the end of a statement, then we want to treat that “if” as a singleline, not multiline statement.

# File lib/pry/indent.rb, line 264
def end_of_statement?(last_token, last_kind)
  (last_token =~ %r{^[)\]\}/]$} || STATEMENT_END_TOKENS.include?(last_kind))
end
in_string?() click to toggle source

Are we currently in the middle of a string literal.

This is used to determine whether to re-indent a given line, we mustn't re-indent within string literals because to do so would actually change the value of the String!

@return Boolean

# File lib/pry/indent.rb, line 275
def in_string?
  !open_delimiters.empty?
end
indent(input) click to toggle source

Indents a string and returns it. This string can either be a single line or multiple ones.

@example

str = <<TXT
class User
attr_accessor :name
end
TXT

# This would result in the following being displayed:
#
# class User
#   attr_accessor :name
# end
#
puts Pry::Indent.new.indent(str)

@param [String] input The input string to indent. @return [String] The indented version of input.

# File lib/pry/indent.rb, line 142
def indent(input)
  output = ''
  prefix = indent_level

  input.lines.each do |line|
    if in_string?
      tokens = tokenize("#{open_delimiters_line}\n#{line}")
      tokens = tokens.drop_while do |token, _type|
        !(token.is_a?(String) && token.include?("\n"))
      end
      previously_in_string = true
    else
      tokens = tokenize(line)
      previously_in_string = false
    end

    before, after = indentation_delta(tokens)

    before.times { prefix.sub! SPACES, '' }
    new_prefix = prefix + SPACES * after

    line = prefix + line.lstrip unless previously_in_string

    output += line

    prefix = new_prefix
  end

  @indent_level = prefix

  output
end
indentation_delta(tokens) click to toggle source

Get the change in indentation indicated by the line.

By convention, you remove indent from the line containing end tokens, but add indent to the line after that which contains the start tokens.

This method returns a pair, where the first number is the number of closings on this line (i.e. the number of indents to remove before the line) and the second is the number of openings (i.e. the number of indents to add after this line)

@param [Array] tokens A list of tokens to scan. @return [Array]

# File lib/pry/indent.rb, line 198
def indentation_delta(tokens)
  # We need to keep track of whether we've seen a "for" on this line because
  # if the line ends with "do" then that "do" should be discounted (i.e. we're
  # only opening one level not two) To do this robustly we want to keep track
  # of the indent level at which we saw the for, so we can differentiate
  # between "for x in [1,2,3] do" and "for x in ([1,2,3].map do" properly
  seen_for_at = []

  # When deciding whether an "if" token is the start of a multiline statement,
  # or just the middle of a single-line if statement, we just look at the
  # preceding token, which is tracked here.
  last_token = nil
  last_kind = nil

  # delta keeps track of the total difference from the start of each line after
  # the given token, 0 is just the level at which the current line started for
  # reference.
  remove_before = 0
  add_after = 0

  # If the list of tokens contains a matching closing token the line should
  # not be indented (and thus we should return true).
  tokens.each do |token, kind|
    is_singleline_if =
      SINGLELINE_TOKENS.include?(token) && end_of_statement?(last_token, last_kind)
    is_optional_do = (token == "do" && seen_for_at.include?(add_after - 1))

    unless kind == :space
      last_token = token
      last_kind = kind
    end
    next if IGNORE_TOKENS.include?(kind)

    track_module_nesting(token, kind)

    seen_for_at << add_after if OPTIONAL_DO_TOKENS.include?(token)

    next if is_singleline_if

    if kind == :delimiter
      track_delimiter(token)
    elsif OPEN_TOKENS.key?(token) && !is_optional_do && !is_singleline_if
      @stack << token
      add_after += 1
    elsif token == OPEN_TOKENS[@stack.last]
      popped = @stack.pop
      track_module_nesting_end(popped)
      if add_after == 0
        remove_before += 1
      else
        add_after -= 1
      end
    elsif MIDWAY_TOKENS.include?(token)
      if add_after == 0
        remove_before += 1
        add_after += 1
      end
    end
  end

  [remove_before, add_after]
end
module_nesting() click to toggle source

Return a list of strings which can be used to re-construct the Module.nesting at the current point in the file.

Returns nil if the syntax of the file was not recognizable.

@return [Array<String>]

# File lib/pry/indent.rb, line 376
def module_nesting
  @module_nesting.map do |(kind, token)|
    raise UnparseableNestingError, @module_nesting.inspect if token.nil?

    "#{kind} #{token}"
  end
end
open_delimiters() click to toggle source

All the open delimiters, in the order that they first appeared.

@return [String]

# File lib/pry/indent.rb, line 312
def open_delimiters
  @heredoc_queue + [@string_start].compact
end
open_delimiters_line() click to toggle source

Return a string which restores the CodeRay string status to the correct value by opening HEREDOCs and strings.

@return String

# File lib/pry/indent.rb, line 320
def open_delimiters_line
  "puts #{open_delimiters.join(', ')}"
end
reset() click to toggle source

reset internal state

# File lib/pry/indent.rb, line 110
def reset
  @stack = []
  @indent_level = ''
  @heredoc_queue = []
  @close_heredocs = {}
  @string_start = nil
  @awaiting_class = false
  @module_nesting = []
  self
end
tokenize(string) click to toggle source

Given a string of Ruby code, use CodeRay to export the tokens.

@param [String] string The Ruby to lex @return [Array] An Array of pairs of [token_value, token_type]

# File lib/pry/indent.rb, line 283
def tokenize(string)
  tokens = SyntaxHighlighter.tokenize(string)
  tokens = tokens.tokens.each_slice(2) if tokens.respond_to?(:tokens) # Coderay 1.0.0
  tokens.to_a
end
track_delimiter(token) click to toggle source

Update the internal state about what kind of strings are open.

Most of the complication here comes from the fact that HEREDOCs can be nested. For normal strings (which can't be nested) we assume that CodeRay correctly pairs open-and-close delimiters so we don't bother checking what they are.

@param [String] token The token (of type :delimiter)

# File lib/pry/indent.rb, line 297
def track_delimiter(token)
  case token
  when /^<<-(["'`]?)(.*)\\1/
    @heredoc_queue << token
    @close_heredocs[token] = /^\s*$2/
  when @close_heredocs[@heredoc_queue.first]
    @heredoc_queue.shift
  else
    @string_start = @string_start ? nil : token
  end
end
track_module_nesting(token, kind) click to toggle source

Update the internal state relating to module nesting.

It's responsible for adding to the @module_nesting array, which looks something like:

[“class”, “Foo”], [“module”, “Bar::Baz”], [“class <<”, “self”

]

A nil value in the @module_nesting array happens in two places: either when @awaiting_class is true and we're still waiting for the string to fill that space, or when a parse was rejected.

At the moment this function is quite restricted about what formats it will parse, for example we disallow expressions after the class keyword. This could maybe be improved in the future.

@param [String] token a token from Coderay @param [Symbol] kind the kind of that token

# File lib/pry/indent.rb, line 341
def track_module_nesting(token, kind)
  if kind == :keyword && %w[class module].include?(token)
    @module_nesting << [token, nil]
    @awaiting_class = true
  elsif @awaiting_class
    if kind == :operator && token == "<<" && @module_nesting.last[0] == "class"
      @module_nesting.last[0] = "class <<"
      @awaiting_class = true
    elsif kind == :class && token =~ /\A(self|[A-Z:][A-Za-z0-9_:]*)\z/
      @module_nesting.last[1] = token if kind == :class
      @awaiting_class = false
    else
      # leave @module_nesting[-1]
      @awaiting_class = false
    end
  end
end
track_module_nesting_end(token, kind = :keyword) click to toggle source

Update the internal state relating to module nesting on 'end'.

If the current 'end' pairs up with a class or a module then we should pop an array off of @module_nesting

@param [String] token a token from Coderay @param [Symbol] kind the kind of that token

# File lib/pry/indent.rb, line 366
def track_module_nesting_end(token, kind = :keyword)
  @module_nesting.pop if kind == :keyword && %w[class module].include?(token)
end