Class: ApiQueryLanguage::Sorting::ExpressionLexer

Inherits:
Object
  • Object
show all
Defined in:
lib/api_query_language/sorting/expression_lexer.rex.rb

Overview

The generated lexer ApiQueryLanguage::Sorting::ExpressionLexer

Defined Under Namespace

Classes: LexerError, ScanError

Constant Summary collapse

FIELD_IDENTIFIER =

:stopdoc:

/[A-Za-z][0-9A-Za-z_-]+/
DIRECTION_OPERATOR = 
/asc|desc/

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#filename ⇒ Object

The file name / path



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 29

def filename
  @filename
end

#ss ⇒ Object Also known as: match

The StringScanner for this lexer.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 34

def ss
  @ss
end

#state ⇒ Object

The current lexical state.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 39

def state
  @state
end

Instance Method Details

#action ⇒ Object

Yields on the current action.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 55

def action
  yield
end

#location ⇒ Object

The current location in the parse.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 91

def location
  [
    filename || "<input>"
  ].compact.join(":")
end

#matches ⇒ Object

The match groups for the current scan.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 46

def matches
  m = (1..9).map { |i| ss[i] }
  m.pop until m[-1] or m.empty?
  m
end

#next_token ⇒ Object

Lex the next token.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 100

def next_token
  token = nil

  until ss.eos? or token
    token =
      case state
      when nil
        if text = ss.scan(/#{FIELD_IDENTIFIER}/o)

          action { [:FIELD_IDENTIFIER, text] }
        elsif ss.skip(/:(#{DIRECTION_OPERATOR})/o)

          action { [:DIRECTION_OPERATOR, matches[0]] }
        elsif text = ss.scan(".")

          action { [:FIELD_IDENTIFIER_SEPARATOR, text] }
        elsif text = ss.scan(";")

          action { [:SORT_SEPARATOR, text] }
        elsif ss.skip(/\s+/)

          # do nothing
        else
          text = ss.string[ss.pos..-1]
          raise ScanError, "can not match (#{state.inspect}) at #{location}: '#{text}'"
        end
      else
        raise ScanError, "undefined state at #{location}: '#{state}'"
      end # token = case state

    next unless token # allow functions to trigger redo w/ nil
  end # while

  raise LexerError, "bad lexical result at #{location}: #{token.inspect}" unless
    token.nil? || (Array === token && token.size >= 2)

  # auto-switch state
  self.state = token.last if token && token.first == :state

  token
end

#parse(str, parser) ⇒ Object

def next_token



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 71

def parse str
  self.ss = scanner_class.new str
  self.state ||= nil

  do_parse
end

#parse_file(path) ⇒ Object

Read in and parse the file at path.



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 81

def parse_file path
  self.filename = path
  open path do |f|
    parse f.read
  end
end

#scanner_class ⇒ Object 



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# File 'lib/api_query_language/sorting/expression_lexer.rex.rb', line 63

def scanner_class
  StringScanner
end