Class: MilkTea::Lexer

Inherits:
Object
  • Object
show all
Includes:
CharacterClasses, FormatStrings, Heredocs, Indentation, Numbers, Recovery, Strings, Symbols, Trivia
Defined in:
lib/milk_tea/core/lexer.rb,
lib/milk_tea/core/lexer/trivia.rb,
lib/milk_tea/core/lexer/numbers.rb,
lib/milk_tea/core/lexer/strings.rb,
lib/milk_tea/core/lexer/symbols.rb,
lib/milk_tea/core/lexer/heredocs.rb,
lib/milk_tea/core/lexer/recovery.rb,
lib/milk_tea/core/lexer/indentation.rb,
lib/milk_tea/core/lexer/format_strings.rb,
lib/milk_tea/core/lexer/character_classes.rb

Defined Under Namespace

Modules: CharacterClasses, FormatStrings, Heredocs, Indentation, Numbers, Recovery, Strings, Symbols, Trivia Classes: LexResult, StringLexResult, StringSegment

Constant Summary collapse

TOP_LEVEL_RESYNC_PREFIXES = 
%w[
  attribute const enum external flags foreign function include import interface
  link opaque public static_assert struct type union var variant extending event
].freeze
LINE_CONTINUATION_OPERATORS = 
%i[
  dot_dot
  plus minus star slash percent
  pipe amp caret
  or and
  equal_equal bang_equal
  less less_equal greater greater_equal
  shift_left shift_right
].freeze
THREE_CHAR_TOKENS = 
{
  "..." => :ellipsis,
  "<<=" => :shift_left_equal,
  ">>=" => :shift_right_equal,
}.freeze
TWO_CHAR_TOKENS = 
{
  "->" => :arrow,
  ".." => :dot_dot,
  "<<" => :shift_left,
  ">>" => :shift_right,
  "+=" => :plus_equal,
  "-=" => :minus_equal,
  "*=" => :star_equal,
  "/=" => :slash_equal,
  "%=" => :percent_equal,
  "&=" => :amp_equal,
  "|=" => :pipe_equal,
  "^=" => :caret_equal,
  "==" => :equal_equal,
  "!=" => :bang_equal,
  "<=" => :less_equal,
  ">=" => :greater_equal,
}.freeze
ONE_CHAR_TOKENS = 
{
  "&" => :amp,
  "@" => :at,
  ":" => :colon,
  "," => :comma,
  "^" => :caret,
  "." => :dot,
  "(" => :lparen,
  ")" => :rparen,
  "|" => :pipe,
  "[" => :lbracket,
  "]" => :rbracket,
  "?" => :question,
  "=" => :equal,
  "+" => :plus,
  "-" => :minus,
  "*" => :star,
  "/" => :slash,
  "%" => :percent,
  "<" => :less,
  ">" => :greater,
  "~" => :tilde,
}.freeze
INTEGER_SUFFIX_STRINGS = 
%w[ub us ul iz b s i u l z].sort_by { |s| -s.length }.freeze
IDENT_START_BYTE =

Byte-classification lookup tables (indexed 0..255). Scanning by raw byte via String#getbyte avoids allocating a one-character String and running the regex engine for every source character, which dominated lexing.

Array.new(256) { |b| b.chr.match?(/[A-Za-z_]/) }.freeze
IDENT_PART_BYTE = 
Array.new(256) { |b| b.chr.match?(/[A-Za-z0-9_]/) }.freeze
DIGIT_BYTE = 
Array.new(256) { |b| b.chr.match?(/[0-9]/) }.freeze
NUMERIC_PART_BYTE = 
Array.new(256) { |b| b.chr.match?(/[0-9_]/) }.freeze
HEX_DIGIT_BYTE = 
Array.new(256) { |b| b.chr.match?(/[0-9a-fA-F_]/) }.freeze
BIN_DIGIT_BYTE = 
Array.new(256) { |b| b.chr.match?(/[01_]/) }.freeze
SPACE_BYTE = 
" ".ord

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Recovery

#top_level_resync_line?

Methods included from Symbols

#adjust_grouping_depth, #lex_symbol

Methods included from FormatStrings

#advance_heredoc_position, #format_spec_suffix?, #lex_format_string, #parse_format_heredoc_parts, #scan_format_interpolation_end, #skip_interpolation_string_contents, #skip_string_contents, #split_format_interpolation_source

Methods included from Heredocs

#dedent_heredoc_content, #dedent_heredoc_lines, #heredoc_content_margin, #heredoc_context_allowed?, #heredoc_prefix, #heredoc_start?, #heredoc_terminator?, #lex_heredoc

Methods included from Strings

#decode_escape, #lex_char_literal, #lex_string, #scan_string_segment

Methods included from Numbers

#exponent_part?, #lex_number, #parse_integer, #scan_integer_suffix_at

Methods included from Indentation

#emit_indentation, #recover_indentation

Methods included from Trivia

#append_trailing_or_pending, #push_pending_leading_trivia, #register_detached_line_trivia, #with_trivia?

Methods included from CharacterClasses

#digit?, #identifier_part?, #identifier_start?, #identifier_start_token, #leading_space_count, #lex_identifier

Constructor Details

#initialize(source, path: nil, mode: :syntax_only, recovery_errors: nil) ⇒ Lexer

Returns a new instance of Lexer.



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# File 'lib/milk_tea/core/lexer.rb', line 126

def initialize(source, path: nil, mode: :syntax_only, recovery_errors: nil)
  @source = source.gsub(/\r\n?/, "\n")
  @path = path
  @mode = mode
  @recovery_errors = recovery_errors
  @tokens = []
  @trivia = []
  @pending_leading_trivia = []
  @indent_stack = [0]
  @grouping_depth = 0
  @grouping_start_line = 0
  @grouping_start_column = 0
  @line_count = @source.empty? ? 1 : @source.lines.count
  @continuation_pending = false
end

Class Method Details

.lex(source, path: nil, mode: :syntax_only, recovery_errors: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lexer.rb', line 117

def self.lex(source, path: nil, mode: :syntax_only, recovery_errors: nil)
  result = new(source, path: path, mode:, recovery_errors:).lex
  mode == :with_trivia ? result.tokens : result
end

.lex_with_trivia(source, path: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lexer.rb', line 122

def self.lex_with_trivia(source, path: nil)
  new(source, path: path, mode: :with_trivia).lex
end

Instance Method Details

#consume_pending_leading_trivia ⇒ Object 



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# File 'lib/milk_tea/core/lexer.rb', line 420

def consume_pending_leading_trivia
  return [] unless with_trivia?

  trivia = @pending_leading_trivia
  @pending_leading_trivia = []
  trivia
end

#emit_line_newline(line, line_number, line_offset, has_newline) ⇒ Object

── newline emission ────────────────────────────────────────────



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# File 'lib/milk_tea/core/lexer.rb', line 384

def emit_line_newline(line, line_number, line_offset, has_newline)
  newline_start = line_offset + line.bytesize
  newline_end = has_newline ? (newline_start + 1) : newline_start

  if @grouping_depth.zero?
    @tokens << token(:newline, "\n", nil, line_number, line.bytesize + 1, start_offset: newline_start, end_offset: newline_end)
  elsif with_trivia? && has_newline
    append_trailing_or_pending(
      TriviaToken.new(
        kind: :newline,
        text: "\n",
        line: line_number,
        column: line.bytesize + 1,
        start_offset: newline_start,
        end_offset: newline_end,
      ),
    )
  end
end

#lex ⇒ Object 



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# File 'lib/milk_tea/core/lexer.rb', line 142

def lex
  lines = @source.each_line.to_a
  line_offset = 0
  line_number = 1
  line_index = 0

  while line_index < lines.length
    raw_line = lines[line_index]
    has_newline = raw_line.end_with?("\n")
    line = raw_line.delete_suffix("\n").b
    consumed_lines = lex_line(lines, line_index, line, line_number, line_offset, has_newline:)

    consumed_lines.times do |delta|
      line_offset += lines.fetch(line_index + delta).bytesize
    end
    line_number += consumed_lines
    line_index += consumed_lines
  end

  if @grouping_depth.positive?
    if @recovery_errors
      @recovery_errors << LexError.new("unclosed grouping delimiter", line: @grouping_start_line, column: @grouping_start_column, path: @path)
      @grouping_depth = 0
    else
      raise LexError.new("unclosed grouping delimiter", line: @line_count, column: 1, path: @path)
    end
  end

  while @indent_stack.length > 1
    @indent_stack.pop
    @tokens << token(:dedent, "", nil, @line_count, 1, start_offset: @source.bytesize, end_offset: @source.bytesize)
  end

  @tokens << token(:eof, "", nil, @line_count + 1, 1, start_offset: @source.bytesize, end_offset: @source.bytesize)
  return LexResult.new(tokens: @tokens, trivia: @trivia) if with_trivia?

  @tokens
end

#lex_line(lines, line_index, line, line_number, line_offset, has_newline:) ⇒ Object 



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# File 'lib/milk_tea/core/lexer.rb', line 191

def lex_line(lines, line_index, line, line_number, line_offset, has_newline:)
  tab_index = line.index("\t")
  if tab_index
    error = LexError.new("tabs are not allowed; use 4 spaces for indentation", line: line_number, column: tab_index + 1, path: @path)
    if @recovery_errors
      @recovery_errors << error
      line = line.gsub("\t", "    ")
    else
      raise error
    end
  end

  if line.strip.empty?
    register_detached_line_trivia(:blank_line, line, line_number, line_offset, has_newline:)
    return 1
  end

  if line.lstrip.start_with?("#")
    register_detached_line_trivia(:comment, line, line_number, line_offset, has_newline:)
    return 1
  end

  index = leading_space_count(line)
  if @recovery_errors && @grouping_depth.positive? && index.zero? && top_level_resync_line?(line)
    @recovery_errors << LexError.new("unclosed grouping delimiter", line: @grouping_start_line, column: @grouping_start_column, path: @path)
    @grouping_depth = 0
    @tokens << token(:newline, "\n", nil, line_number, 1, start_offset: line_offset, end_offset: line_offset)
  end

  if with_trivia? && index.positive?
    push_pending_leading_trivia(
      TriviaToken.new(
        kind: :space,
        text: line[0...index],
        line: line_number,
        column: 1,
        start_offset: line_offset,
        end_offset: line_offset + index,
      ),
    )
  end

  if @grouping_depth.zero?
    if @continuation_pending
    elsif @recovery_errors
      begin
        emit_indentation(index, line_number, line_offset)
      rescue LexError => e
        @recovery_errors << e
        recover_indentation(index, line_number, line_offset)
      end
    else
      emit_indentation(index, line_number, line_offset)
    end
  end
  @continuation_pending = false

  while index < line.length
    char = line[index]

    if char == " "
      if with_trivia?
        span_start = index
        index += 1 while index < line.length && line[index] == " "
        push_pending_leading_trivia(
          TriviaToken.new(
            kind: :space,
            text: line[span_start...index],
            line: line_number,
            column: span_start + 1,
            start_offset: line_offset + span_start,
            end_offset: line_offset + index,
          ),
        )
        next
      end

      index += 1
      next
    end

    if char == "#"
      if with_trivia?
        comment_end = line.length
        comment_text = line[index...comment_end]
        append_trailing_or_pending(
          TriviaToken.new(
            kind: :comment,
            text: comment_text,
            line: line_number,
            column: index + 1,
            start_offset: line_offset + index,
            end_offset: line_offset + comment_end,
          ),
        )
      end
      break
    end

    if char == "c" && heredoc_start?(line, index, cstring: true)
      return lex_heredoc(lines, line_index, index, line_number, line_offset, cstring: true)
    end

    if char == "c" && line[index + 1] == "<" && line[index + 2] == "-" && identifier_start?(line[index + 3])
      error = LexError.new("expected '<<-' for heredoc string; did you mean 'c<<-#{identifier_start_token(line, index + 3)}'?", line: line_number, column: index + 1, path: @path)
      if @recovery_errors
        @recovery_errors << error
      else
        raise error
      end
    end
    if char == "c" && line[index + 1] == '"'
      result = lex_string(lines, line_index, line, index, line_number, line_offset:, cstring: true)
      return result.consumed_lines if result.consumed_lines > 1

      index = result.next_index
      next
    end

    if char == "f" && heredoc_start?(line, index, format: true)
      return lex_heredoc(lines, line_index, index, line_number, line_offset, cstring: false, format: true)
    end

    if char == "f" && line[index + 1] == "<" && line[index + 2] == "-" && identifier_start?(line[index + 3])
      error = LexError.new("expected '<<-' for heredoc string; did you mean 'f<<-#{identifier_start_token(line, index + 3)}'?", line: line_number, column: index + 1, path: @path)
      if @recovery_errors
        @recovery_errors << error
      else
        raise error
      end
    end

    if char == "f" && line[index + 1] == '"'
      index = lex_format_string(line, index, line_number, line_offset:)
      next
    end

    if char == "<" && heredoc_start?(line, index)
      return lex_heredoc(lines, line_index, index, line_number, line_offset, cstring: false)
    end

    if char == '"'
      result = lex_string(lines, line_index, line, index, line_number, line_offset:)
      return result.consumed_lines if result.consumed_lines > 1

      index = result.next_index
      next
    end

    if char == "'"
      index = lex_char_literal(line, index, line_number, line_offset:)
      next
    end

    if identifier_start?(char)
      index = lex_identifier(line, index, line_number, line_offset:)
      next
    end

    if digit?(char)
      index = lex_number(line, index, line_number, line_offset:)
      next
    end

    index = lex_symbol(line, index, line_number, line_offset:)
  end

  newline_start = line_offset + line.length
  newline_end = has_newline ? (newline_start + 1) : newline_start
  if @grouping_depth.zero?
    if LINE_CONTINUATION_OPERATORS.include?(@tokens.last&.type)
      @continuation_pending = true
    else
      @tokens << token(:newline, "\n", nil, line_number, line.length + 1, start_offset: newline_start, end_offset: newline_end)
    end
  elsif with_trivia? && has_newline
    append_trailing_or_pending(
      TriviaToken.new(
        kind: :newline,
        text: "\n",
        line: line_number,
        column: line.length + 1,
        start_offset: newline_start,
        end_offset: newline_end,
      ),
    )
  end

  1
end

#token(type, lexeme, literal, line, column, start_offset:, end_offset:) ⇒ Object

── token construction ──────────────────────────────────────────



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# File 'lib/milk_tea/core/lexer.rb', line 406

def token(type, lexeme, literal, line, column, start_offset:, end_offset:)
  Token.new(
    type:,
    lexeme:,
    literal:,
    line:,
    column:,
    start_offset:,
    end_offset:,
    leading_trivia: consume_pending_leading_trivia,
    trailing_trivia: [],
  )
end