# class Prism::Translation::Parser

This class is the entry-point for converting a prism syntax tree into the whitequark/parser gem’s syntax tree. It inherits from the base parser for the parser gem, and overrides the parse* methods to parse with prism and then translate.

### Public Instance Methods

default_encoding ()
Source

    # File lib/prism/translation/parser.rb, line 41
    def default_encoding
      Encoding::UTF_8
    end

The default encoding for Ruby files is UTF-8.

parse (source_buffer)
Source

    # File lib/prism/translation/parser.rb, line 49
    def parse(source_buffer)
      @source_buffer = source_buffer
      source = source_buffer.source

      offset_cache = build_offset_cache(source)
      result = unwrap(Prism.parse(source, filepath: source_buffer.name, version: convert_for_prism(version), partial_script: true, encoding: false), offset_cache)

      build_ast(result.value, offset_cache)
    ensure
      @source_buffer = nil
    end

Parses a source buffer and returns the AST.

parse_with_comments (source_buffer)
Source

    # File lib/prism/translation/parser.rb, line 62
    def parse_with_comments(source_buffer)
      @source_buffer = source_buffer
      source = source_buffer.source

      offset_cache = build_offset_cache(source)
      result = unwrap(Prism.parse(source, filepath: source_buffer.name, version: convert_for_prism(version), partial_script: true, encoding: false), offset_cache)

      [
        build_ast(result.value, offset_cache),
        build_comments(result.comments, offset_cache)
      ]
    ensure
      @source_buffer = nil
    end

Parses a source buffer and returns the AST and the source code comments.

tokenize (source_buffer, recover = false)
Source

    # File lib/prism/translation/parser.rb, line 79
    def tokenize(source_buffer, recover = false)
      @source_buffer = source_buffer
      source = source_buffer.source

      offset_cache = build_offset_cache(source)
      result =
        begin
          unwrap(Prism.parse_lex(source, filepath: source_buffer.name, version: convert_for_prism(version), partial_script: true, encoding: false), offset_cache)
        rescue ::Parser::SyntaxError
          raise if !recover
        end

      program, tokens = result.value
      ast = build_ast(program, offset_cache) if result.success?

      [
        ast,
        build_comments(result.comments, offset_cache),
        build_tokens(tokens, offset_cache)
      ]
    ensure
      @source_buffer = nil
    end

Parses a source buffer and returns the AST, the source code comments, and the tokens emitted by the lexer.

try_declare_numparam (node)
Source

    # File lib/prism/translation/parser.rb, line 105
    def try_declare_numparam(node)
      node.children[0].match?(/\A_[1-9]\z/)
    end

Since prism resolves num params for us, we don’t need to support this kind of logic here.

### Private Instance Methods

build_ast (program, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 263
    def build_ast(program, offset_cache)
      program.accept(Compiler.new(self, offset_cache))
    end

Build the parser gem AST from the prism AST.

build_comments (comments, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 268
    def build_comments(comments, offset_cache)
      comments.map do |comment|
        ::Parser::Source::Comment.new(build_range(comment.location, offset_cache))
      end
    end

Build the parser gem comments from the prism comments.

build_offset_cache (source)
Source

    # File lib/prism/translation/parser.rb, line 246
    def build_offset_cache(source)
      if source.bytesize == source.length
        -> (offset) { offset }
      else
        offset_cache = []
        offset = 0

        source.each_char do |char|
          char.bytesize.times { offset_cache << offset }
          offset += 1
        end

        offset_cache << offset
      end
    end

`Prism` deals with offsets in bytes, while the parser gem deals with offsets in characters. We need to handle this conversion in order to build the parser gem AST.

If the bytesize of the source is the same as the length, then we can just use the offset directly. Otherwise, we build an array where the index is the byte offset and the value is the character offset.

build_range (location, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 280
    def build_range(location, offset_cache)
      ::Parser::Source::Range.new(
        source_buffer,
        offset_cache[location.start_offset],
        offset_cache[location.end_offset]
      )
    end

Build a range from a prism location.

build_tokens (tokens, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 275
    def build_tokens(tokens, offset_cache)
      Lexer.new(source_buffer, tokens, offset_cache).to_a
    end

Build the parser gem tokens from the prism tokens.

convert_for_prism (version)
Source

    # File lib/prism/translation/parser.rb, line 289
    def convert_for_prism(version)
      case version
      when 33
        "3.3.1"
      when 34
        "3.4.0"
      else
        "latest"
      end
    end

Converts the version format handled by `Parser` to the format handled by `Prism`.

error_diagnostic (error, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 124
    def error_diagnostic(error, offset_cache)
      location = error.location
      diagnostic_location = build_range(location, offset_cache)

      case error.type
      when :argument_block_multi
        Diagnostic.new(:error, :block_and_blockarg, {}, diagnostic_location, [])
      when :argument_formal_constant
        Diagnostic.new(:error, :argument_const, {}, diagnostic_location, [])
      when :argument_formal_class
        Diagnostic.new(:error, :argument_cvar, {}, diagnostic_location, [])
      when :argument_formal_global
        Diagnostic.new(:error, :argument_gvar, {}, diagnostic_location, [])
      when :argument_formal_ivar
        Diagnostic.new(:error, :argument_ivar, {}, diagnostic_location, [])
      when :argument_no_forwarding_amp
        Diagnostic.new(:error, :no_anonymous_blockarg, {}, diagnostic_location, [])
      when :argument_no_forwarding_star
        Diagnostic.new(:error, :no_anonymous_restarg, {}, diagnostic_location, [])
      when :argument_no_forwarding_star_star
        Diagnostic.new(:error, :no_anonymous_kwrestarg, {}, diagnostic_location, [])
      when :begin_lonely_else
        location = location.copy(length: 4)
        diagnostic_location = build_range(location, offset_cache)
        Diagnostic.new(:error, :useless_else, {}, diagnostic_location, [])
      when :class_name, :module_name
        Diagnostic.new(:error, :module_name_const, {}, diagnostic_location, [])
      when :class_in_method
        Diagnostic.new(:error, :class_in_def, {}, diagnostic_location, [])
      when :def_endless_setter
        Diagnostic.new(:error, :endless_setter, {}, diagnostic_location, [])
      when :embdoc_term
        Diagnostic.new(:error, :embedded_document, {}, diagnostic_location, [])
      when :incomplete_variable_class, :incomplete_variable_class_3_3
        location = location.copy(length: location.length + 1)
        diagnostic_location = build_range(location, offset_cache)

        Diagnostic.new(:error, :cvar_name, { name: location.slice }, diagnostic_location, [])
      when :incomplete_variable_instance, :incomplete_variable_instance_3_3
        location = location.copy(length: location.length + 1)
        diagnostic_location = build_range(location, offset_cache)

        Diagnostic.new(:error, :ivar_name, { name: location.slice }, diagnostic_location, [])
      when :invalid_variable_global, :invalid_variable_global_3_3
        Diagnostic.new(:error, :gvar_name, { name: location.slice }, diagnostic_location, [])
      when :module_in_method
        Diagnostic.new(:error, :module_in_def, {}, diagnostic_location, [])
      when :numbered_parameter_ordinary
        Diagnostic.new(:error, :ordinary_param_defined, {}, diagnostic_location, [])
      when :numbered_parameter_outer_scope
        Diagnostic.new(:error, :numparam_used_in_outer_scope, {}, diagnostic_location, [])
      when :parameter_circular
        Diagnostic.new(:error, :circular_argument_reference, { var_name: location.slice }, diagnostic_location, [])
      when :parameter_name_repeat
        Diagnostic.new(:error, :duplicate_argument, {}, diagnostic_location, [])
      when :parameter_numbered_reserved
        Diagnostic.new(:error, :reserved_for_numparam, { name: location.slice }, diagnostic_location, [])
      when :regexp_unknown_options
        Diagnostic.new(:error, :regexp_options, { options: location.slice[1..] }, diagnostic_location, [])
      when :singleton_for_literals
        Diagnostic.new(:error, :singleton_literal, {}, diagnostic_location, [])
      when :string_literal_eof
        Diagnostic.new(:error, :string_eof, {}, diagnostic_location, [])
      when :unexpected_token_ignore
        Diagnostic.new(:error, :unexpected_token, { token: location.slice }, diagnostic_location, [])
      when :write_target_in_method
        Diagnostic.new(:error, :dynamic_const, {}, diagnostic_location, [])
      else
        PrismDiagnostic.new(error.message, :error, error.type, diagnostic_location)
      end
    end

Build a diagnostic from the given prism parse error.

unwrap (result, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 224
    def unwrap(result, offset_cache)
      result.errors.each do |error|
        next unless valid_error?(error)
        diagnostics.process(error_diagnostic(error, offset_cache))
      end

      result.warnings.each do |warning|
        next unless valid_warning?(warning)
        diagnostic = warning_diagnostic(warning, offset_cache)
        diagnostics.process(diagnostic) if diagnostic
      end

      result
    end

If there was a error generated during the parse, then raise an appropriate syntax error. Otherwise return the result.

valid_error? (error)
Source

    # File lib/prism/translation/parser.rb, line 113
    def valid_error?(error)
      true
    end

This is a hook to allow consumers to disable some errors if they don’t want them to block creating the syntax tree.

valid_warning? (warning)
Source

    # File lib/prism/translation/parser.rb, line 119
    def valid_warning?(warning)
      true
    end

This is a hook to allow consumers to disable some warnings if they don’t want them to block creating the syntax tree.

warning_diagnostic (warning, offset_cache)
Source

    # File lib/prism/translation/parser.rb, line 197
    def warning_diagnostic(warning, offset_cache)
      diagnostic_location = build_range(warning.location, offset_cache)

      case warning.type
      when :ambiguous_first_argument_plus
        Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "+" }, diagnostic_location, [])
      when :ambiguous_first_argument_minus
        Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "-" }, diagnostic_location, [])
      when :ambiguous_prefix_ampersand
        Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "&" }, diagnostic_location, [])
      when :ambiguous_prefix_star
        Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "*" }, diagnostic_location, [])
      when :ambiguous_prefix_star_star
        Diagnostic.new(:warning, :ambiguous_prefix, { prefix: "**" }, diagnostic_location, [])
      when :ambiguous_slash
        Diagnostic.new(:warning, :ambiguous_regexp, {}, diagnostic_location, [])
      when :dot_dot_dot_eol
        Diagnostic.new(:warning, :triple_dot_at_eol, {}, diagnostic_location, [])
      when :duplicated_hash_key
        # skip, parser does this on its own
      else
        PrismDiagnostic.new(warning.message, :warning, warning.type, diagnostic_location)
      end
    end

Build a diagnostic from the given prism parse warning.