# class ErrorHighlight::Spotter

### Public Class Methods

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

    # File lib/error_highlight/base.rb, line 79
    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 101
    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,
          script_lines: @node.script_lines,
        }
      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 507
    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 285
    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 259
    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 244
    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 200
    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 463
    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 355
    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 341
    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 408
    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 383
    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 451
    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 430
    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 481
    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 326
    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 305
    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 368
    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