class SyntaxSuggest::LeftRightTokenCount

Find mis-matched syntax based on lexical count

Used for detecting missing pairs of elements each keyword needs an end, each ‘{’ needs a ‘}’ etc.

Example:

left_right = LeftRightTokenCount.new
left_right.count_kw
left_right.missing.first
# => "end"

left_right = LeftRightTokenCount.new
source = "{ a: b, c: d" # Note missing '}'
LexAll.new(source: source).each do |token|
  left_right.count_token(token)
end
left_right.missing.first
# => "}"

Constants

PAIRS

Public Class Methods

new ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 25
def initialize
  @kw_count = 0
  @end_count = 0

  @count_for_char = {
    "{" => 0,
    "}" => 0,
    "[" => 0,
    "]" => 0,
    "(" => 0,
    ")" => 0,
    "|" => 0
  }
end

Public Instance Methods

count_end ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 44
def count_end
  @end_count += 1
end

count_for_char (char)

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 95
def count_for_char(char)
  @count_for_char[char]
end

count_kw ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 40
def count_kw
  @kw_count += 1
end

count_token (token)

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 59
def count_token(token)
  case token.type
  when :STRING_CONTENT
    # ^^^
    # Means it's a string or a symbol `"{"` rather than being
    # part of a data structure (like a hash) `{ a: b }`
    # ignore it.
  when :PERCENT_UPPER_W, :PERCENT_UPPER_I, :PERCENT_LOWER_W,
       :PERCENT_LOWER_I, :REGEXP_BEGIN, :STRING_BEGIN
    # ^^^
    # Handle shorthand syntaxes like `%Q{ i am a string }`
    #
    # The start token will be the full thing `%Q{` but we
    # need to count it as if it's a `{`. Any token
    # can be used
    char = token.value[-1]
    @count_for_char[char] += 1 if @count_for_char.key?(char)
  when :EMBEXPR_BEGIN
    # ^^^
    # Embedded string expressions like `"#{foo} <-embed"`
    # are parsed with chars:
    #
    # `#{` as :EMBEXPR_BEGIN
    #  `}` as :EMBEXPR_END
    #
    # When we see `#{` count it as a `{` or we will
    # have a mis-match count.
    #
    @count_for_char["{"] += 1
  else
    @end_count += 1 if token.is_end?
    @kw_count += 1 if token.is_kw?
    @count_for_char[token.value] += 1 if @count_for_char.key?(token.value)
  end
end

Count source code characters

Example:

token = CodeLine.from_source("{").first.tokens.first
left_right = LeftRightTokenCount.new
left_right.count_token(Token.new(token)
left_right.count_for_char("{")
# => 1
left_right.count_for_char("}")
# => 0

missing ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 104
def missing
  out = missing_pairs
  out << missing_pipe
  out << missing_keyword_end
  out.compact!
  out
end

Returns an array of missing syntax characters or ‘“end”` or `“keyword”`

left_right.missing
# => ["}"]

Private Instance Methods

missing_keyword_end ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 142
        def missing_keyword_end
  case @kw_count <=> @end_count
  when 1
    "end"
  when 0
    nil
  when -1
    "keyword"
  end
end

Keywords need ends and ends need keywords

If we have more keywords, there’s a missing end if we have more end-s, there’s a missing keyword

missing_pairs ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 125
        def missing_pairs
  PAIRS.map do |(left, right)|
    case @count_for_char[left] <=> @count_for_char[right]
    when 1
      right
    when 0
      nil
    when -1
      left
    end
  end
end

Opening characters like ‘{` need closing characters # like `}`.

When a mis-match count is detected, suggest the missing member.

For example if there are 3 ‘}` and only two `{` return `“{”`

missing_pipe ()

Source

# File lib/syntax_suggest/left_right_token_count.rb, line 156
        def missing_pipe
  if @count_for_char["|"].odd?
    "|"
  end
end

Pipes come in pairs. If there’s an odd number of pipes then we are missing one