class ErrorHighlight::Spotter

Public Class Methods

new(node, point_type: :name, name: nil) click to toggle source

# File lib/error_highlight/base.rb, line 27
def initialize(node, point_type: :name, name: nil)
  @node = node
  @point_type = point_type
  @name = name

  # Not-implemented-yet options
  @arg = nil # Specify the index or keyword at which argument caused the TypeError/ArgumentError
  @multiline = false # Allow multiline spot

  @fetch = -> (lineno, last_lineno = lineno) do
    snippet = @node.script_lines[lineno - 1 .. last_lineno - 1].join("")
    snippet += "\n" unless snippet.end_with?("\n")

    # It require some work to support Unicode (or multibyte) characters.
    # Tentatively, we stop highlighting if the code snippet has non-ascii characters.
    # See https://github.com/ruby/error_highlight/issues/4
    raise NonAscii unless snippet.ascii_only?

    snippet
  end
end

Public Instance Methods

spot() click to toggle source

# File lib/error_highlight/base.rb, line 49
def spot
  return nil unless @node

  case @node.type

  when :CALL, :QCALL
    case @point_type
    when :name
      spot_call_for_name
    when :args
      spot_call_for_args
    end

  when :ATTRASGN
    case @point_type
    when :name
      spot_attrasgn_for_name
    when :args
      spot_attrasgn_for_args
    end

  when :OPCALL
    case @point_type
    when :name
      spot_opcall_for_name
    when :args
      spot_opcall_for_args
    end

  when :FCALL
    case @point_type
    when :name
      spot_fcall_for_name
    when :args
      spot_fcall_for_args
    end

  when :VCALL
    spot_vcall

  when :OP_ASGN1
    case @point_type
    when :name
      spot_op_asgn1_for_name
    when :args
      spot_op_asgn1_for_args
    end

  when :OP_ASGN2
    case @point_type
    when :name
      spot_op_asgn2_for_name
    when :args
      spot_op_asgn2_for_args
    end

  when :CONST
    spot_vcall

  when :COLON2
    spot_colon2

  when :COLON3
    spot_vcall

  when :OP_CDECL
    spot_op_cdecl
  end

  if @snippet && @beg_column && @end_column && @beg_column < @end_column
    return {
      first_lineno: @beg_lineno,
      first_column: @beg_column,
      last_lineno: @end_lineno,
      last_column: @end_column,
      snippet: @snippet,
    }
  else
    return nil
  end

rescue NonAscii
  nil
end

Private Instance Methods

fetch_line(lineno) click to toggle source

# File lib/error_highlight/base.rb, line 454
def fetch_line(lineno)
  @beg_lineno = @end_lineno = lineno
  @snippet = @fetch[lineno]
end

spot_attrasgn_for_args() click to toggle source

Example:

x.foo = 1
        ^
x[42] = 1
  ^^^^^^^
x[] = 1
  ^^^^^

# File lib/error_highlight/base.rb, line 232
def spot_attrasgn_for_args
  nd_recv, mid, nd_args = @node.children
  fetch_line(nd_recv.last_lineno)
  if mid == :[]= && @snippet.match(/\G[\s)]*\[/, nd_recv.last_column)
    @beg_column = $~.end(0)
    if nd_recv.last_lineno == nd_args.last_lineno
      @end_column = nd_args.last_column
    end
  elsif nd_args && nd_args.first_lineno == nd_args.last_lineno
    @beg_column = nd_args.first_column
    @end_column = nd_args.last_column
  end
  # TODO: support @arg
end

spot_attrasgn_for_name() click to toggle source

Example:

x.foo = 1
 ^^^^^^
x[42] = 1
 ^^^^^^

# File lib/error_highlight/base.rb, line 206
def spot_attrasgn_for_name
  nd_recv, mid, nd_args = @node.children
  *nd_args, _nd_last_arg, _nil = nd_args.children
  fetch_line(nd_recv.last_lineno)
  if mid == :[]= && @snippet.match(/\G[\s)]*(\[)/, nd_recv.last_column)
    @beg_column = $~.begin(1)
    args_last_column = $~.end(0)
    if nd_args.last && nd_recv.last_lineno == nd_args.last.last_lineno
      args_last_column = nd_args.last.last_column
    end
    if @snippet.match(/[\s)]*\]\s*=/, args_last_column)
      @end_column = $~.end(0)
    end
  elsif @snippet.match(/\G[\s)]*(\.\s*#{ Regexp.quote(mid.to_s.sub(/=\z/, "")) }\s*=)/, nd_recv.last_column)
    @beg_column = $~.begin(1)
    @end_column = $~.end(1)
  end
end

spot_call_for_args() click to toggle source

Example:

x.foo(42)
      ^^
x[42]
  ^^
x += 1
     ^

# File lib/error_highlight/base.rb, line 191
def spot_call_for_args
  _nd_recv, _mid, nd_args = @node.children
  if nd_args && nd_args.first_lineno == nd_args.last_lineno
    fetch_line(nd_args.first_lineno)
    @beg_column = nd_args.first_column
    @end_column = nd_args.last_column
  end
  # TODO: support @arg
end

spot_call_for_name() click to toggle source

Example:

x.foo
 ^^^^
x.foo(42)
 ^^^^
x&.foo
 ^^^^^
x[42]
 ^^^^
x += 1
  ^

# File lib/error_highlight/base.rb, line 147
def spot_call_for_name
  nd_recv, mid, nd_args = @node.children
  lineno = nd_recv.last_lineno
  lines = @fetch[lineno, @node.last_lineno]
  if mid == :[] && lines.match(/\G[\s)]*(\[(?:\s*\])?)/, nd_recv.last_column)
    @beg_column = $~.begin(1)
    @snippet = lines[/.*\n/]
    @beg_lineno = @end_lineno = lineno
    if nd_args
      if nd_recv.last_lineno == nd_args.last_lineno && @snippet.match(/\s*\]/, nd_args.last_column)
        @end_column = $~.end(0)
      end
    else
      if lines.match(/\G[\s)]*?\[\s*\]/, nd_recv.last_column)
        @end_column = $~.end(0)
      end
    end
  elsif lines.match(/\G[\s)]*?(\&?\.)(\s*?)(#{ Regexp.quote(mid) }).*\n/, nd_recv.last_column)
    lines = $` + $&
    @beg_column = $~.begin($2.include?("\n") ? 3 : 1)
    @end_column = $~.end(3)
    if i = lines[..@beg_column].rindex("\n")
      @beg_lineno = @end_lineno = lineno + lines[..@beg_column].count("\n")
      @snippet = lines[i + 1..]
      @beg_column -= i + 1
      @end_column -= i + 1
    else
      @snippet = lines
      @beg_lineno = @end_lineno = lineno
    end
  elsif mid.to_s =~ /\A\W+\z/ && lines.match(/\G\s*(#{ Regexp.quote(mid) })=.*\n/, nd_recv.last_column)
    @snippet = $` + $&
    @beg_column = $~.begin(1)
    @end_column = $~.end(1)
  end
end

spot_colon2() click to toggle source

Example:

Foo::Bar
   ^^^^^

# File lib/error_highlight/base.rb, line 410
def spot_colon2
  nd_parent, const = @node.children
  if nd_parent.last_lineno == @node.last_lineno
    fetch_line(nd_parent.last_lineno)
    @beg_column = nd_parent.last_column
    @end_column = @node.last_column
  else
    @snippet = @fetch[@node.last_lineno]
    if @snippet[...@node.last_column].match(/#{ Regexp.quote(const) }\z/)
      @beg_column = $~.begin(0)
      @end_column = $~.end(0)
    end
  end
end

spot_fcall_for_args() click to toggle source

Example:

foo(42)
    ^^
foo 42
    ^^

# File lib/error_highlight/base.rb, line 302
def spot_fcall_for_args
  _mid, nd_args = @node.children
  if nd_args && nd_args.first_lineno == nd_args.last_lineno
    # binary operator
    fetch_line(nd_args.first_lineno)
    @beg_column = nd_args.first_column
    @end_column = nd_args.last_column
  end
end

spot_fcall_for_name() click to toggle source

Example:

foo(42)
^^^
foo 42
^^^

# File lib/error_highlight/base.rb, line 288
def spot_fcall_for_name
  mid, _nd_args = @node.children
  fetch_line(@node.first_lineno)
  if @snippet.match(/(#{ Regexp.quote(mid) })/, @node.first_column)
    @beg_column = $~.begin(1)
    @end_column = $~.end(1)
  end
end

spot_op_asgn1_for_args() click to toggle source

Example:

x[1] += 42
  ^^^^^^^^

# File lib/error_highlight/base.rb, line 355
def spot_op_asgn1_for_args
  nd_recv, mid, nd_args, nd_rhs = @node.children
  fetch_line(nd_recv.last_lineno)
  if mid == :[]= && @snippet.match(/\G\s*\[/, nd_recv.last_column)
    @beg_column = $~.end(0)
    if nd_recv.last_lineno == nd_rhs.last_lineno
      @end_column = nd_rhs.last_column
    end
  elsif nd_args && nd_args.first_lineno == nd_rhs.last_lineno
    @beg_column = nd_args.first_column
    @end_column = nd_rhs.last_column
  end
  # TODO: support @arg
end

spot_op_asgn1_for_name() click to toggle source

Example:

x[1] += 42
 ^^^    (for [])
x[1] += 42
     ^  (for +)
x[1] += 42
 ^^^^^^ (for []=)

# File lib/error_highlight/base.rb, line 330
def spot_op_asgn1_for_name
  nd_recv, op, nd_args, _nd_rhs = @node.children
  fetch_line(nd_recv.last_lineno)
  if @snippet.match(/\G[\s)]*(\[)/, nd_recv.last_column)
    bracket_beg_column = $~.begin(1)
    args_last_column = $~.end(0)
    if nd_args && nd_recv.last_lineno == nd_args.last_lineno
      args_last_column = nd_args.last_column
    end
    if @snippet.match(/\s*\](\s*)(#{ Regexp.quote(op) })=()/, args_last_column)
      case @name
      when :[], :[]=
        @beg_column = bracket_beg_column
        @end_column = $~.begin(@name == :[] ? 1 : 3)
      when op
        @beg_column = $~.begin(2)
        @end_column = $~.end(2)
      end
    end
  end
end

spot_op_asgn2_for_args() click to toggle source

Example:

x.foo += 42
         ^^

# File lib/error_highlight/base.rb, line 398
def spot_op_asgn2_for_args
  _nd_recv, _qcall, _attr, _op, nd_rhs = @node.children
  if nd_rhs.first_lineno == nd_rhs.last_lineno
    fetch_line(nd_rhs.first_lineno)
    @beg_column = nd_rhs.first_column
    @end_column = nd_rhs.last_column
  end
end

spot_op_asgn2_for_name() click to toggle source

Example:

x.foo += 42
 ^^^     (for foo)
x.foo += 42
      ^  (for +)
x.foo += 42
 ^^^^^^^ (for foo=)

# File lib/error_highlight/base.rb, line 377
def spot_op_asgn2_for_name
  nd_recv, _qcall, attr, op, _nd_rhs = @node.children
  fetch_line(nd_recv.last_lineno)
  if @snippet.match(/\G[\s)]*(\.)\s*#{ Regexp.quote(attr) }()\s*(#{ Regexp.quote(op) })(=)/, nd_recv.last_column)
    case @name
    when attr
      @beg_column = $~.begin(1)
      @end_column = $~.begin(2)
    when op
      @beg_column = $~.begin(3)
      @end_column = $~.end(3)
    when :"#{ attr }="
      @beg_column = $~.begin(1)
      @end_column = $~.end(4)
    end
  end
end

spot_op_cdecl() click to toggle source

Example:

Foo::Bar += 1
   ^^^^^^^^

# File lib/error_highlight/base.rb, line 428
def spot_op_cdecl
  nd_lhs, op, _nd_rhs = @node.children
  *nd_parent_lhs, _const = nd_lhs.children
  if @name == op
    @snippet = @fetch[nd_lhs.last_lineno]
    if @snippet.match(/\G\s*(#{ Regexp.quote(op) })=/, nd_lhs.last_column)
      @beg_column = $~.begin(1)
      @end_column = $~.end(1)
    end
  else
    # constant access error
    @end_column = nd_lhs.last_column
    if nd_parent_lhs.empty? # example: ::C += 1
      if nd_lhs.first_lineno == nd_lhs.last_lineno
        @snippet = @fetch[nd_lhs.last_lineno]
        @beg_column = nd_lhs.first_column
      end
    else # example: Foo::Bar::C += 1
      if nd_parent_lhs.last.last_lineno == nd_lhs.last_lineno
        @snippet = @fetch[nd_lhs.last_lineno]
        @beg_column = nd_parent_lhs.last.last_column
      end
    end
  end
end

spot_opcall_for_args() click to toggle source

Example:

x + 1
    ^

# File lib/error_highlight/base.rb, line 273
def spot_opcall_for_args
  _nd_recv, _op, nd_arg = @node.children
  if nd_arg && nd_arg.first_lineno == nd_arg.last_lineno
    # binary operator
    fetch_line(nd_arg.first_lineno)
    @beg_column = nd_arg.first_column
    @end_column = nd_arg.last_column
  end
end

spot_opcall_for_name() click to toggle source

Example:

x + 1
  ^
+x
^

# File lib/error_highlight/base.rb, line 252
def spot_opcall_for_name
  nd_recv, op, nd_arg = @node.children
  fetch_line(nd_recv.last_lineno)
  if nd_arg
    # binary operator
    if @snippet.match(/\G[\s)]*(#{ Regexp.quote(op) })/, nd_recv.last_column)
      @beg_column = $~.begin(1)
      @end_column = $~.end(1)
    end
  else
    # unary operator
    if @snippet[...nd_recv.first_column].match(/(#{ Regexp.quote(op.to_s.sub(/@\z/, "")) })\s*\(?\s*\z/)
      @beg_column = $~.begin(1)
      @end_column = $~.end(1)
    end
  end
end

spot_vcall() click to toggle source

Example:

foo
^^^

# File lib/error_highlight/base.rb, line 315
def spot_vcall
  if @node.first_lineno == @node.last_lineno
    fetch_line(@node.last_lineno)
    @beg_column = @node.first_column
    @end_column = @node.last_column
  end
end