ctags for crystal language

crystal-tags.cr

require "compiler/crystal/**"
require "option_parser"

include Crystal

class ToCtagsVisitor < Visitor
  TAG_NAMES = {
    "c" => "class",
    "f" => "method",
    "s" => "struct",
    "m" => "module",
    "l" => "library",
    "t" => "type"
  }
  def initialize(@filename, @lines, @io, @opts)
    @scopes = [] of String
    @to_s_visitor = ToSVisitor.new(@io)
  end

  def visit(node)
    true
  end

  def visit(node: ClassDef)
    visit_scope_node(node, "c")
  end

  def visit(node: ModuleDef)
    visit_scope_node(node, "m")
  end

  def visit(node: StructOrUnionDef)
    visit_scope_node(node, "s")
  end

  def visit(node: LibDef)
    visit_scope_node(node, "l")
  end

  def end_visit(node: ClassDef | ModuleDef | StructOrUnionDef | LibDef)
    return unless node.location
    pop_scope
  end

  def visit(node: Def | TypeDef | FunDef | Alias | Macro)
    location = node.location
    if location
      @io << node.name
      @io << "\t"
      @io << @filename
      @io << "\t"
      print_location(location)
      @io << ";\"\t"
      case node
      when TypeDef, Alias
        print_type "t"
      else
        print_type "f"
      end
      print_flags location
      @io << "\n"
    end
    true
  end

  private def print_location(location)
    case @opts.excmd
    when "pattern"
      @io << "/^#{regexp_escape(@lines[location.line_number-1])}$/"
    when "number"
      @io << location.line_number
    else
      raise "Invalid option"
    end
  end

  private def regexp_escape(str)
    String.build do |result|
      str.each_byte do |byte|
        case byte.chr
        when '\\', '?', '[', '^', ']', '$'
          result << '\\'
          result.write_byte byte
        when '\n'
          # get rid of spurious lf
        else
          result.write_byte byte
        end
      end
    end
  end

  private def visit_scope_node(node, type)
    location = node.location
    if location
      @io << node.name
      @io << "\t"
      @io << @filename
      @io << "\t"
      print_location location
      @io << ";\"\t"
      print_type type
      print_flags location
      @io << "\n"
      push_scope node.name
    end
    true
  end

  private def push_scope(node)
    case node
    when Path
      buf = [] of String
      node.names.each_with_index do |name, i|
        buf << "::" if i > 0 || node.global
        buf << name
      end
      @scopes << buf.join
    when String
      @scopes << node
    else
      @scopes << node.class.name
    end
  end

  private def pop_scope
    @scopes.pop?
  end

  private def print_type(tag)
    if @opts.show_short_tag
      @io << tag
    else
      @io << TAG_NAMES[tag]
    end
  end

  private def print_flags(location)
    if @opts.show_scope && !@scopes.empty?
      @io << "\tclass:#{@scopes.join(".")}"
    end
    if @opts.show_line_tags
      @io << "\tline:#{location.line_number}"
    end
  end
end

class Generator
  property :tag_fn, :excmd, :fields

  def initialize(@tag_fn, @fields, @excmd)
  end

  def show_line_tags
    @fields.index('n')
  end

  def show_short_tag
    !@fields.index('K')
  end

  def show_long_tag
    @fields.index('K')
  end

  def show_scope
    @fields.index('s')
  end

  def generate(filename)
    output do |f|
      f.puts "!_TAG_FILE_FORMAT	2	/extended format; --format=1 will not append ;\" to lines/"
      f.puts "!_TAG_FILE_SORTED	0	/0=unsorted, 1=sorted, 2=foldcase/"
      f.puts "!_TAG_PROGRAM_AUTHOR	Kent Sibilev	//"
      f.puts "!_TAG_PROGRAM_URL	crystal-tags	//"
      f.puts "!_TAG_PROGRAM_VERSION	1.0	//"

      if File.directory?(filename)
        walk_dir(filename) do |fn|
          if File.extname(fn) == ".cr"
            generate_tags(f, fn)
          end
        end
      else
        if File.extname(filename) == ".cr"
          generate_tags(f, filename)
        else
          STDERR.puts "#{filename} doesn't have .cr extention"
          exit -1
        end
      end
    end
  end

  private def generate_tags(io, filename)
    data = File.read(filename)
    parser = Parser.new(data)
    parser.filename = filename
    parser.wants_doc = false
    node = parser.parse
    node.accept(ToCtagsVisitor.new(filename, data.lines, io, self))
  rescue ex : Crystal::Exception
    STDERR.puts ex
  end

  private def walk_dir(dir, &block : String ->)
    Dir.entries(dir).each do |fn|
      filename = File.join(dir, fn)
      block.call filename
      if File.directory?(filename) && !fn.starts_with?(".")
        walk_dir(filename, &block)
      end
    end
  end

  private def output
    if @tag_fn == "-"
      yield STDOUT
    else
      File.open(@tag_fn, "w") do |f|
        yield f
      end
    end
  end
end

generator = Generator.new "tags", "nks", "pattern"

begin
  OptionParser.parse! do |p|
    p.on("-f FILE", "specify the output file, '-' will output to standard output") do |v|
      generator.tag_fn = v
    end
    p.on("--excmd EXCMD", "specify the type of EX command used. Either 'pattern' or 'number'") do |v|
      unless %w[pattern number].includes?(v)
        raise OptionParser::InvalidOption.new("Invalid excmd option #{v}")
      end
      generator.excmd = v
    end
    p.on("-n", "equivalent to --excmd number") do
      generator.excmd = "number"
    end
    p.on("-N", "equivalent to --excmd pattern") do
      generator.excmd = "pattern"
    end
    p.on("--fields FIELDS", "specify the available extention fields. k - single letter tag, K - full tag name, n - line number of tag definition, s - scope of tag definition") do |v|
      generator.fields = v
    end
  end
rescue OptionParser::InvalidOption
  STDOUT.puts "Usage: #{$0} -s <TAG_FILE> <FILE.CR>"
  exit -1
end


filename = ARGV.first? || "."
generator.generate(filename)