Class: RText::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/rtext/parser.rb

Defined Under Namespace

Classes: InternalError, Problem

Constant Summary collapse

AnyValue = 
[:identifier, :integer, :float, :string, :boolean, :reference, :generic]

Instance Method Summary collapse

Instance Method Details

#consume(*args) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 199

def consume(*args)
  t = @tokens.first
  if t.nil?
    @non_consume_count += 1
    report_consume_problem("Unexpected end of file, expected #{args.join(", ")}", @last_line)
    return nil
  end
  if args.include?(t.kind)
    @tokens.shift
    @consume_problem_reported = false
    @non_consume_count = 0
    puts "consuming #{t.kind} #{t.value}" if @debug
    t
  else
    if t.kind == :error
      @tokens.shift
      @non_consume_count = 0
      report_consume_problem("Parse error on token '#{t.value}'", t.line)
      return nil
    else
      value = " '#{t.value}'" if t.value
      @non_consume_count += 1
      report_consume_problem("Unexpected #{t.kind}#{value}, expected #{args.join(", ")}", t.line)
      return nil
    end
  end
end

#discard_until(kind) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 187

def discard_until(kind)
  t = @tokens.shift
  if t
    puts "discarding #{t.kind} #{t.value}" if @debug
    while t.kind != kind
      t = @tokens.shift
      break unless t
      puts "discarding #{t.kind} #{t.value}" if @debug
    end
  end
end

#next_token_kind(idx = 0) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 183

def next_token_kind(idx=0)
  @tokens[idx] && @tokens[idx].kind
end

#parse(tokens, options) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 8

def parse(tokens, options)
  @dsc_visitor = options[:descent_visitor]
  @asc_visitor = options[:ascent_visitor]
  @problems = options[:problems] || []
  @non_consume_count = 0
  @consume_problem_reported = false
  @tokens = tokens
  @last_line = @tokens.last && @tokens.last.line 
  #@debug = true
  begin
    while next_token_kind
      statement = parse_statement(true, true)
    end
  rescue InternalError
  end
end

#parse_annotation ⇒ Object 



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# File 'lib/rtext/parser.rb', line 70

def parse_annotation
  result = nil
  while next_token_kind == :annotation
    result ||= []
    result << consume(:annotation)
    consume(:newline)
  end
  result
end

#parse_argument(arg_list) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 142

def parse_argument(arg_list)
  if next_token_kind == :label
    label = consume(:label)
    arg_list << [label, parse_argument_value]
  else
    arg_list << parse_argument_value
  end
end

#parse_argument_list(arg_list) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 130

def parse_argument_list(arg_list)
  first = true
  while (AnyValue + [",", "[", :label, :error]).include?(next_token_kind)
    unless first
      success = consume(",")
      consume(:newline) if success && next_token_kind == :newline
    end
    first = false
    parse_argument(arg_list)
  end
end

#parse_argument_value ⇒ Object 



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# File 'lib/rtext/parser.rb', line 151

def parse_argument_value
  if next_token_kind == "["
    parse_argument_value_list
  else
    parse_value
  end
end

#parse_argument_value_list ⇒ Object 



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# File 'lib/rtext/parser.rb', line 159

def parse_argument_value_list
  consume("[")
  consume(:newline) if next_token_kind == :newline
  first = true
  result = []
  while (AnyValue + [",", :error]).include?(next_token_kind)
    unless first
      success = consume(",")
      consume(:newline) if success && next_token_kind == :newline
    end
    first = false
    result << parse_value
  end
  consume(:newline) if next_token_kind == :newline && next_token_kind(1) == "]"
  consume("]")
  result
end

#parse_block_element(element_list, comments) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 98

def parse_block_element(element_list, comments)
  if next_token_kind == :label
    label = consume(:label)
    element_list << [label, parse_labeled_block_element(comments)]
  else
    statement = parse_statement(false, true)
    element_list << statement if statement 
  end
end

#parse_comment ⇒ Object 



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# File 'lib/rtext/parser.rb', line 60

def parse_comment
  result = nil 
  while next_token_kind == :comment
    result ||= []
    result << consume(:comment)
    consume(:newline)
  end
  result
end

#parse_element_list(comments) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 117

def parse_element_list(comments)
  consume("[")
  parse_eol_comment(comments)
  result = []
  while next_token_kind && next_token_kind != "]"
    statement = parse_statement(false, true)
    result << statement if statement 
  end
  consume("]")
  parse_eol_comment(comments)
  result
end

#parse_eol_comment(comments) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 80

def parse_eol_comment(comments)
  if next_token_kind == :comment
    comment = consume(:comment)
    comments << [comment, :eol]
  end
  nl = consume(:newline)
  discard_until(:newline) unless nl
end

#parse_labeled_block_element(comments) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 108

def parse_labeled_block_element(comments)
  if next_token_kind == "["
    parse_element_list(comments)
  else
    parse_eol_comment(comments)
    parse_statement
  end
end

#parse_statement(is_root = false, allow_unassociated_comment = false) ⇒ Object

parse a statement with optional leading comment or an unassociated comment



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# File 'lib/rtext/parser.rb', line 26

def parse_statement(is_root=false, allow_unassociated_comment=false)
  comments = [] 
  comment = parse_comment 
  annotation = parse_annotation
  if (next_token_kind && next_token_kind == :identifier) || !allow_unassociated_comment
    comments << [ comment, :above] if comment
    command = consume(:identifier)
    if command
      @dsc_visitor.call(command)
      arg_list = []
      parse_argument_list(arg_list)
      element_list = []
      if next_token_kind == "{"
        parse_statement_block(element_list, comments)
      end
      parse_eol_comment(comments)
      @asc_visitor.call(command, arg_list, element_list, comments, annotation, is_root)
    else
      discard_until(:newline)
      nil
    end
  elsif comment
    # if there is no statement, the comment is non-optional
    comments << [ comment, :unassociated ]
    @asc_visitor.call(nil, nil, nil, comments, nil, nil)
    nil
  else
    # die expecting an identifier (next token is not an identifier)
    consume(:identifier)
    discard_until(:newline)
    nil
  end
end

#parse_statement_block(element_list, comments) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 89

def parse_statement_block(element_list, comments)
  consume("{")
  parse_eol_comment(comments)
  while next_token_kind && next_token_kind != "}"
    parse_block_element(element_list, comments)
  end
  consume("}")
end

#parse_value ⇒ Object 



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# File 'lib/rtext/parser.rb', line 179

def parse_value
  consume(*AnyValue)
end

#report_consume_problem(message, line) ⇒ Object 



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# File 'lib/rtext/parser.rb', line 230

def report_consume_problem(message, line)
  problem = Problem.new(message, line)
  if @non_consume_count > 100
    # safety check, stop reoccuring problems to avoid endless loops
    @problems << Problem.new("Internal error", line) 
    puts [@problems.last.message, @problems.last.line].inspect if @debug
    raise InternalError.new
  else
    if !@consume_problem_reported
      @consume_problem_reported = true
      @problems << problem 
      puts [@problems.last.message, @problems.last.line].inspect if @debug
    end
  end
end