Mini Shell

# frozen_string_literal: true
require 'ripper'

class RDoc::Parser::RipperStateLex
  # TODO: Remove this constants after Ruby 2.4 EOL
  RIPPER_HAS_LEX_STATE = Ripper::Filter.method_defined?(:state)

  Token = Struct.new(:line_no, :char_no, :kind, :text, :state)

  EXPR_NONE = 0
  EXPR_BEG = 1
  EXPR_END = 2
  EXPR_ENDARG = 4
  EXPR_ENDFN = 8
  EXPR_ARG = 16
  EXPR_CMDARG = 32
  EXPR_MID = 64
  EXPR_FNAME = 128
  EXPR_DOT = 256
  EXPR_CLASS = 512
  EXPR_LABEL = 1024
  EXPR_LABELED = 2048
  EXPR_FITEM = 4096
  EXPR_VALUE = EXPR_BEG
  EXPR_BEG_ANY  =  (EXPR_BEG | EXPR_MID | EXPR_CLASS)
  EXPR_ARG_ANY  =  (EXPR_ARG | EXPR_CMDARG)
  EXPR_END_ANY  =  (EXPR_END | EXPR_ENDARG | EXPR_ENDFN)

  class InnerStateLex < Ripper::Filter
    attr_accessor :lex_state

    def initialize(code)
      @lex_state = EXPR_BEG
      @in_fname = false
      @continue = false
      reset
      super(code)
    end

    def reset
      @command_start = false
      @cmd_state = @command_start
    end

    def on_nl(tok, data)
      case @lex_state
      when EXPR_FNAME, EXPR_DOT
        @continue = true
      else
        @continue = false
        @lex_state = EXPR_BEG unless (EXPR_LABEL & @lex_state) != 0
      end
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_ignored_nl(tok, data)
      case @lex_state
      when EXPR_FNAME, EXPR_DOT
        @continue = true
      else
        @continue = false
        @lex_state = EXPR_BEG unless (EXPR_LABEL & @lex_state) != 0
      end
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_op(tok, data)
      case tok
      when '&', '|', '!', '!=', '!~'
        case @lex_state
        when EXPR_FNAME, EXPR_DOT
          @lex_state = EXPR_ARG
        else
          @lex_state = EXPR_BEG
        end
      when '<<'
        # TODO next token?
        case @lex_state
        when EXPR_FNAME, EXPR_DOT
          @lex_state = EXPR_ARG
        else
          @lex_state = EXPR_BEG
        end
      when '?'
        @lex_state = EXPR_BEG
      when '&&', '||', '+=', '-=', '*=', '**=',
           '&=', '|=', '^=', '<<=', '>>=', '||=', '&&='
        @lex_state = EXPR_BEG
      when '::'
        case @lex_state
        when EXPR_ARG, EXPR_CMDARG
          @lex_state = EXPR_DOT
        when EXPR_FNAME, EXPR_DOT
          @lex_state = EXPR_ARG
        else
          @lex_state = EXPR_BEG
        end
      else
        case @lex_state
        when EXPR_FNAME, EXPR_DOT
          @lex_state = EXPR_ARG
        else
          @lex_state = EXPR_BEG
        end
      end
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_kw(tok, data)
      case tok
      when 'class'
        @lex_state = EXPR_CLASS
        @in_fname = true
      when 'def'
        @lex_state = EXPR_FNAME
        @continue = true
        @in_fname = true
      when 'if', 'unless', 'while', 'until'
        if ((EXPR_MID | EXPR_END | EXPR_ENDARG | EXPR_ENDFN | EXPR_ARG | EXPR_CMDARG) & @lex_state) != 0 # postfix if
          @lex_state = EXPR_BEG | EXPR_LABEL
        else
          @lex_state = EXPR_BEG
        end
      when 'begin', 'case', 'when'
        @lex_state = EXPR_BEG
      when 'return', 'break'
        @lex_state = EXPR_MID
      else
        if @lex_state == EXPR_FNAME
          @lex_state = EXPR_END
        else
          @lex_state = EXPR_END
        end
      end
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_tstring_beg(tok, data)
      @lex_state = EXPR_BEG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_tstring_end(tok, data)
      @lex_state = EXPR_END | EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_CHAR(tok, data)
      @lex_state = EXPR_END
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_period(tok, data)
      @lex_state = EXPR_DOT
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_int(tok, data)
      @lex_state = EXPR_END | EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_float(tok, data)
      @lex_state = EXPR_END | EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_rational(tok, data)
      @lex_state = EXPR_END | EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_imaginary(tok, data)
      @lex_state = EXPR_END | EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_symbeg(tok, data)
      @lex_state = EXPR_FNAME
      @continue = true
      @in_fname = true
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    private def on_variables(event, tok, data)
      if @in_fname
        @lex_state = EXPR_ENDFN
        @in_fname = false
        @continue = false
      elsif @continue
        case @lex_state
        when EXPR_DOT
          @lex_state = EXPR_ARG
        else
          @lex_state = EXPR_ENDFN
          @continue = false
        end
      else
        @lex_state = EXPR_CMDARG
      end
      data << Token.new(lineno, column, event, tok, @lex_state)
    end

    def on_ident(tok, data)
      on_variables(__method__, tok, data)
    end

    def on_ivar(tok, data)
      @lex_state = EXPR_END
      on_variables(__method__, tok, data)
    end

    def on_cvar(tok, data)
      @lex_state = EXPR_END
      on_variables(__method__, tok, data)
    end

    def on_gvar(tok, data)
      @lex_state = EXPR_END
      on_variables(__method__, tok, data)
    end

    def on_backref(tok, data)
      @lex_state = EXPR_END
      on_variables(__method__, tok, data)
    end

    def on_lparen(tok, data)
      @lex_state = EXPR_LABEL | EXPR_BEG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_rparen(tok, data)
      @lex_state = EXPR_ENDFN
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_lbrace(tok, data)
      @lex_state = EXPR_LABEL | EXPR_BEG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_rbrace(tok, data)
      @lex_state = EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_lbracket(tok, data)
      @lex_state = EXPR_LABEL | EXPR_BEG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_rbracket(tok, data)
      @lex_state = EXPR_ENDARG
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_const(tok, data)
      case @lex_state
      when EXPR_FNAME
        @lex_state = EXPR_ENDFN
      when EXPR_CLASS, EXPR_CMDARG, EXPR_MID
        @lex_state = EXPR_ARG
      else
        @lex_state = EXPR_CMDARG
      end
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_sp(tok, data)
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_comma(tok, data)
      @lex_state = EXPR_BEG | EXPR_LABEL if (EXPR_ARG_ANY & @lex_state) != 0
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_comment(tok, data)
      @lex_state = EXPR_BEG unless (EXPR_LABEL & @lex_state) != 0
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_ignored_sp(tok, data)
      @lex_state = EXPR_BEG unless (EXPR_LABEL & @lex_state) != 0
      data << Token.new(lineno, column, __method__, tok, @lex_state)
    end

    def on_heredoc_beg(tok, data)
      data << Token.new(lineno, column, __method__, tok, @lex_state)
      @lex_state = EXPR_END
      data
    end

    def on_heredoc_end(tok, data)
      data << Token.new(lineno, column, __method__, tok, @lex_state)
      @lex_state = EXPR_BEG
      data
    end

    def on_default(event, tok, data)
      reset
      data << Token.new(lineno, column, event, tok, @lex_state)
    end
  end unless RIPPER_HAS_LEX_STATE

  class InnerStateLex < Ripper::Filter
    def initialize(code)
      super(code)
    end

    def on_default(event, tok, data)
      data << Token.new(lineno, column, event, tok, state)
    end
  end if RIPPER_HAS_LEX_STATE

  def get_squashed_tk
    if @buf.empty?
      tk = @tokens.shift
    else
      tk = @buf.shift
    end
    return nil if tk.nil?
    case tk[:kind]
    when :on_symbeg then
      tk = get_symbol_tk(tk)
    when :on_tstring_beg then
      tk = get_string_tk(tk)
    when :on_backtick then
      if (tk[:state] & (EXPR_FNAME | EXPR_ENDFN)) != 0
        @inner_lex.lex_state = EXPR_ARG unless RIPPER_HAS_LEX_STATE
        tk[:kind] = :on_ident
        tk[:state] = Ripper::Lexer.const_defined?(:State) ? Ripper::Lexer::State.new(EXPR_ARG) : EXPR_ARG
      else
        tk = get_string_tk(tk)
      end
    when :on_regexp_beg then
      tk = get_regexp_tk(tk)
    when :on_embdoc_beg then
      tk = get_embdoc_tk(tk)
    when :on_heredoc_beg then
      @heredoc_queue << retrieve_heredoc_info(tk)
      @inner_lex.lex_state = EXPR_END unless RIPPER_HAS_LEX_STATE
    when :on_nl, :on_ignored_nl, :on_comment, :on_heredoc_end then
      if !@heredoc_queue.empty?
        get_heredoc_tk(*@heredoc_queue.shift)
      elsif tk[:text].nil? # :on_ignored_nl sometimes gives nil
        tk[:text] = ''
      end
    when :on_words_beg then
      tk = get_words_tk(tk)
    when :on_qwords_beg then
      tk = get_words_tk(tk)
    when :on_symbols_beg then
      tk = get_words_tk(tk)
    when :on_qsymbols_beg then
      tk = get_words_tk(tk)
    when :on_op then
      if '&.' == tk[:text]
        tk[:kind] = :on_period
      else
        tk = get_op_tk(tk)
      end
    end
    tk
  end

  private def get_symbol_tk(tk)
    is_symbol = true
    symbol_tk = Token.new(tk.line_no, tk.char_no, :on_symbol)
    if ":'" == tk[:text] or ':"' == tk[:text]
      tk1 = get_string_tk(tk)
      symbol_tk[:text] = tk1[:text]
      symbol_tk[:state] = tk1[:state]
    else
      case (tk1 = get_squashed_tk)[:kind]
      when :on_ident
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_tstring_content
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = get_squashed_tk[:state] # skip :on_tstring_end
      when :on_tstring_end
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_op
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_ivar
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_cvar
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_gvar
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_const
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      when :on_kw
        symbol_tk[:text] = ":#{tk1[:text]}"
        symbol_tk[:state] = tk1[:state]
      else
        is_symbol = false
        tk = tk1
      end
    end
    if is_symbol
      tk = symbol_tk
    end
    tk
  end

  private def get_string_tk(tk)
    string = tk[:text]
    state = nil
    kind = :on_tstring
    loop do
      inner_str_tk = get_squashed_tk
      if inner_str_tk.nil?
        break
      elsif :on_tstring_end == inner_str_tk[:kind]
        string = string + inner_str_tk[:text]
        state = inner_str_tk[:state]
        break
      elsif :on_label_end == inner_str_tk[:kind]
        string = string + inner_str_tk[:text]
        state = inner_str_tk[:state]
        kind = :on_symbol
        break
      else
        string = string + inner_str_tk[:text]
        if :on_embexpr_beg == inner_str_tk[:kind] then
          kind = :on_dstring if :on_tstring == kind
        end
      end
    end
    Token.new(tk.line_no, tk.char_no, kind, string, state)
  end

  private def get_regexp_tk(tk)
    string = tk[:text]
    state = nil
    loop do
      inner_str_tk = get_squashed_tk
      if inner_str_tk.nil?
        break
      elsif :on_regexp_end == inner_str_tk[:kind]
        string = string + inner_str_tk[:text]
        state = inner_str_tk[:state]
        break
      else
        string = string + inner_str_tk[:text]
      end
    end
    Token.new(tk.line_no, tk.char_no, :on_regexp, string, state)
  end

  private def get_embdoc_tk(tk)
    string = tk[:text]
    until :on_embdoc_end == (embdoc_tk = get_squashed_tk)[:kind] do
      string = string + embdoc_tk[:text]
    end
    string = string + embdoc_tk[:text]
    Token.new(tk.line_no, tk.char_no, :on_embdoc, string, embdoc_tk.state)
  end

  private def get_heredoc_tk(heredoc_name, indent)
    string = ''
    start_tk = nil
    prev_tk = nil
    until heredoc_end?(heredoc_name, indent, tk = @tokens.shift) do
      start_tk = tk unless start_tk
      if (prev_tk.nil? or "\n" == prev_tk[:text][-1]) and 0 != tk[:char_no]
        string = string + (' ' * tk[:char_no])
      end
      string = string + tk[:text]
      prev_tk = tk
    end
    start_tk = tk unless start_tk
    prev_tk = tk unless prev_tk
    @buf.unshift tk # closing heredoc
    heredoc_tk = Token.new(start_tk.line_no, start_tk.char_no, :on_heredoc, string, prev_tk.state)
    @buf.unshift heredoc_tk
  end

  private def retrieve_heredoc_info(tk)
    name = tk[:text].gsub(/\A<<[-~]?(['"`]?)(.+)\1\z/, '\2')
    indent = tk[:text] =~ /\A<<[-~]/
    [name, indent]
  end

  private def heredoc_end?(name, indent, tk)
    result = false
    if :on_heredoc_end == tk[:kind] then
      tk_name = tk[:text].chomp
      tk_name.lstrip! if indent
      if name == tk_name
        result = true
      end
    end
    result
  end

  private def get_words_tk(tk)
    string = ''
    start_token = tk[:text]
    start_quote = tk[:text].rstrip[-1]
    line_no = tk[:line_no]
    char_no = tk[:char_no]
    state = tk[:state]
    end_quote =
      case start_quote
      when ?( then ?)
      when ?[ then ?]
      when ?{ then ?}
      when ?< then ?>
      else start_quote
      end
    end_token = nil
    loop do
      tk = get_squashed_tk
      if tk.nil?
        end_token = end_quote
        break
      elsif :on_tstring_content == tk[:kind] then
        string += tk[:text]
      elsif :on_words_sep == tk[:kind] or :on_tstring_end == tk[:kind] then
        if end_quote == tk[:text].strip then
          end_token = tk[:text]
          break
        else
          string += tk[:text]
        end
      else
        string += tk[:text]
      end
    end
    text = "#{start_token}#{string}#{end_token}"
    Token.new(line_no, char_no, :on_dstring, text, state)
  end

  private def get_op_tk(tk)
    redefinable_operators = %w[! != !~ % & * ** + +@ - -@ / < << <= <=> == === =~ > >= >> [] []= ^ ` | ~]
    if redefinable_operators.include?(tk[:text]) and tk[:state] == EXPR_ARG then
      @inner_lex.lex_state = EXPR_ARG unless RIPPER_HAS_LEX_STATE
      tk[:state] = Ripper::Lexer.const_defined?(:State) ? Ripper::Lexer::State.new(EXPR_ARG) : EXPR_ARG
      tk[:kind] = :on_ident
    elsif tk[:text] =~ /^[-+]$/ then
      tk_ahead = get_squashed_tk
      case tk_ahead[:kind]
      when :on_int, :on_float, :on_rational, :on_imaginary then
        tk[:text] += tk_ahead[:text]
        tk[:kind] = tk_ahead[:kind]
        tk[:state] = tk_ahead[:state]
      when :on_heredoc_beg, :on_tstring, :on_dstring # frozen/non-frozen string literal
        tk[:text] += tk_ahead[:text]
        tk[:kind] = tk_ahead[:kind]
        tk[:state] = tk_ahead[:state]
      else
        @buf.unshift tk_ahead
      end
    end
    tk
  end

  def initialize(code)
    @buf = []
    @heredoc_queue = []
    @inner_lex = InnerStateLex.new(code)
    @tokens = @inner_lex.parse([])
  end

  def self.parse(code)
    lex = self.new(code)
    tokens = []
    begin
      while tk = lex.get_squashed_tk
        tokens.push tk
      end
    rescue StopIteration
    end
    tokens
  end

  def self.end?(token)
    (token[:state] & EXPR_END)
  end
end