Rename error_squiggle to error_highlight

3 files changed, 497 insertions, 0 deletions

diff --git a/lib/error_highlight/base.rb b/lib/error_highlight/base.rb
new file mode 100644
index 0000000000..49c772501c
--- /dev/null
+++ b/lib/error_highlight/base.rb
@@ -0,0 +1,446 @@
+require_relative "version"
+
+module ErrorHighlight
+  # Identify the code fragment that seems associated with a given error
+  #
+  # Arguments:
+  #  node: RubyVM::AbstractSyntaxTree::Node
+  #  point: :name | :args
+  #  name: The name associated with the NameError/NoMethodError
+  #  fetch: A block to fetch a specified code line (or lines)
+  #
+  # Returns:
+  #  {
+  #    first_lineno: Integer,
+  #    first_column: Integer,
+  #    last_lineno: Integer,
+  #    last_column: Integer,
+  #    line: String,
+  #  } | nil
+  def self.spot(...)
+    Spotter.new(...).spot
+  end
+
+  class Spotter
+    def initialize(node, point, name: nil, &fetch)
+      @node = node
+      @point = point
+      @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 = fetch
+    end
+
+    def spot
+      return nil unless @node
+
+      case @node.type
+
+      when :CALL, :QCALL
+        case @point
+        when :name
+          spot_call_for_name
+        when :args
+          spot_call_for_args
+        end
+
+      when :ATTRASGN
+        case @point
+        when :name
+          spot_attrasgn_for_name
+        when :args
+          spot_attrasgn_for_args
+        end
+
+      when :OPCALL
+        case @point
+        when :name
+          spot_opcall_for_name
+        when :args
+          spot_opcall_for_args
+        end
+
+      when :FCALL
+        case @point
+        when :name
+          spot_fcall_for_name
+        when :args
+          spot_fcall_for_args
+        end
+
+      when :VCALL
+        spot_vcall
+
+      when :OP_ASGN1
+        case @point
+        when :name
+          spot_op_asgn1_for_name
+        when :args
+          spot_op_asgn1_for_args
+        end
+
+      when :OP_ASGN2
+        case @point
+        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 @line && @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,
+          line: @line,
+        }
+      else
+        return nil
+      end
+    end
+
+    private
+
+    # Example:
+    #   x.foo
+    #    ^^^^
+    #   x.foo(42)
+    #    ^^^^
+    #   x&.foo
+    #    ^^^^^
+    #   x[42]
+    #    ^^^^
+    #   x += 1
+    #     ^
+    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)
+        @line = lines[/.*\n/]
+        @beg_lineno = @end_lineno = lineno
+        if nd_args
+          if nd_recv.last_lineno == nd_args.last_lineno && @line.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")
+          @line = lines[i + 1..]
+          @beg_column -= i + 1
+          @end_column -= i + 1
+        else
+          @line = 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)
+        @line = $` + $&
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   x.foo(42)
+    #         ^^
+    #   x[42]
+    #     ^^
+    #   x += 1
+    #        ^
+    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
+
+    # Example:
+    #   x.foo = 1
+    #    ^^^^^^
+    #   x[42] = 1
+    #    ^^^^^^
+    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 == :[]= && @line.match(/\G\s*(\[)/, nd_recv.last_column)
+        @beg_column = $~.begin(1)
+        args_last_column = $~.end(0)
+        if nd_args.last && nd_recv.last_lineno == nd_args.last.last_lineno
+          args_last_column = nd_args.last.last_column
+        end
+        if @line.match(/\s*\]\s*=/, args_last_column)
+          @end_column = $~.end(0)
+        end
+      elsif @line.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
+
+    # Example:
+    #   x.foo = 1
+    #           ^
+    #   x[42] = 1
+    #     ^^^^^^^
+    #   x[] = 1
+    #     ^^^^^
+    def spot_attrasgn_for_args
+      nd_recv, mid, nd_args = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if mid == :[]= && @line.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
+
+    # Example:
+    #   x + 1
+    #     ^
+    #   +x
+    #   ^
+    def spot_opcall_for_name
+      nd_recv, op, nd_arg = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if nd_arg
+        # binary operator
+        if @line.match(/\G\s*(#{ Regexp.quote(op) })/, nd_recv.last_column)
+          @beg_column = $~.begin(1)
+          @end_column = $~.end(1)
+        end
+      else
+        # unary operator
+        if @line[...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
+
+    # Example:
+    #   x + 1
+    #       ^
+    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
+
+    # Example:
+    #   foo(42)
+    #   ^^^
+    #   foo 42
+    #   ^^^
+    def spot_fcall_for_name
+      mid, _nd_args = @node.children
+      fetch_line(@node.first_lineno)
+      if @line.match(/(#{ Regexp.quote(mid) })/, @node.first_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   foo(42)
+    #       ^^
+    #   foo 42
+    #       ^^
+    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
+
+    # Example:
+    #   foo
+    #   ^^^
+    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
+
+    # Example:
+    #   x[1] += 42
+    #    ^^^    (for [])
+    #   x[1] += 42
+    #        ^  (for +)
+    #   x[1] += 42
+    #    ^^^^^^ (for []=)
+    def spot_op_asgn1_for_name
+      nd_recv, op, nd_args, _nd_rhs = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if @line.match(/\G\s*(\[)/, nd_recv.last_column)
+        bracket_beg_column = $~.begin(1)
+        args_last_column = $~.end(0)
+        if nd_args && nd_recv.last_lineno == nd_args.last_lineno
+          args_last_column = nd_args.last_column
+        end
+        if @line.match(/\s*\](\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
+
+    # Example:
+    #   x[1] += 42
+    #     ^^^^^^^^
+    def spot_op_asgn1_for_args
+      nd_recv, mid, nd_args, nd_rhs = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if mid == :[]= && @line.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
+
+    # Example:
+    #   x.foo += 42
+    #    ^^^     (for foo)
+    #   x.foo += 42
+    #         ^  (for +)
+    #   x.foo += 42
+    #    ^^^^^^^ (for foo=)
+    def spot_op_asgn2_for_name
+      nd_recv, _qcall, attr, op, _nd_rhs = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if @line.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
+
+    # Example:
+    #   x.foo += 42
+    #            ^^
+    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
+
+    # Example:
+    #   Foo::Bar
+    #      ^^^^^
+    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
+        @line = @fetch[@node.last_lineno]
+        if @line[...@node.last_column].match(/#{ Regexp.quote(const) }\z/)
+          @beg_column = $~.begin(0)
+          @end_column = $~.end(0)
+        end
+      end
+    end
+
+    # Example:
+    #   Foo::Bar += 1
+    #      ^^^^^^^^
+    def spot_op_cdecl
+      nd_lhs, op, _nd_rhs = @node.children
+      *nd_parent_lhs, _const = nd_lhs.children
+      if @name == op
+        @line = @fetch[nd_lhs.last_lineno]
+        if @line.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
+            @line = @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
+            @line = @fetch[nd_lhs.last_lineno]
+            @beg_column = nd_parent_lhs.last.last_column
+          end
+        end
+      end
+    end
+
+    def fetch_line(lineno)
+      @beg_lineno = @end_lineno = lineno
+      @line = @fetch[lineno]
+    end
+  end
+
+  private_constant :Spotter
+end
diff --git a/lib/error_highlight/core_ext.rb b/lib/error_highlight/core_ext.rb
new file mode 100644
index 0000000000..ad1c15a485
--- /dev/null
+++ b/lib/error_highlight/core_ext.rb
@@ -0,0 +1,48 @@
+module ErrorHighlight
+  module CoreExt
+    SKIP_TO_S_FOR_SUPER_LOOKUP = true
+    private_constant :SKIP_TO_S_FOR_SUPER_LOOKUP
+
+    def to_s
+      msg = super.dup
+
+      locs = backtrace_locations
+      return msg unless locs
+
+      loc = locs.first
+      begin
+        node = RubyVM::AbstractSyntaxTree.of(loc, save_script_lines: true)
+        opts = {}
+
+        case self
+        when NoMethodError, NameError
+          point = :name
+          opts[:name] = name
+        when TypeError, ArgumentError
+          point = :args
+        end
+
+        spot = ErrorHighlight.spot(node, point, **opts) do |lineno, last_lineno|
+          last_lineno ||= lineno
+          node.script_lines[lineno - 1 .. last_lineno - 1].join("")
+        end
+
+      rescue Errno::ENOENT
+      end
+
+      if spot
+        marker = " " * spot[:first_column] + "^" * (spot[:last_column] - spot[:first_column])
+        points = "\n\n#{ spot[:line] }#{ marker }"
+        msg << points if !msg.include?(points)
+      end
+
+      msg
+    end
+  end
+
+  NameError.prepend(CoreExt)
+
+  # temporarily disabled
+  #TypeError.prepend(CoreExt)
+  #ArgumentError.prepend(CoreExt)
+end
diff --git a/lib/error_highlight/version.rb b/lib/error_highlight/version.rb
new file mode 100644
index 0000000000..c41ebd94f1
--- /dev/null
+++ b/lib/error_highlight/version.rb
@@ -0,0 +1,3 @@
+module ErrorHighlight
+  VERSION = "0.1.0"
+end