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
@return [String] String containing the spaces to be inserted before the next line.
@return [Array<String>] The stack of open tokens.
Public Class Methods
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
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
# File lib/pry/indent.rb, line 104 def initialize(pry_instance = Pry.new) @pry_instance = pry_instance reset end
Public Instance Methods
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
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
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
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
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
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
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
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
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 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
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
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
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
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