Class: Sparkql::Lexer

Inherits:
StringScanner
  • Object
show all
Includes:
Token
Defined in:
lib/sparkql/lexer.rb

Constant Summary

Constants included from Token

Token::BOOLEAN, Token::CHARACTER, Token::CONJUNCTIONS, Token::CUSTOM_FIELD, Token::DATE, Token::DATETIME, Token::DECIMAL, Token::EQUALITY_OPERATORS, Token::INTEGER, Token::KEYWORD, Token::LPAREN, Token::NEWLINE, Token::NULL, Token::OPERATORS, Token::RANGE_OPERATOR, Token::RPAREN, Token::SPACE, Token::STANDARD_FIELD, Token::TIME, Token::UNARY_CONJUNCTIONS

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str) ⇒ Lexer

Returns a new instance of Lexer.



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# File 'lib/sparkql/lexer.rb', line 10

def initialize(str)
  str.freeze
  super(str, false) # DO NOT dup str
  @level = 0
  @block_group_identifier = 0
  @expression_count = 0
end

Instance Attribute Details

#block_group_identifier ⇒ Object

Returns the value of attribute block_group_identifier.



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# File 'lib/sparkql/lexer.rb', line 6

def block_group_identifier
  @block_group_identifier
end

#current_token_value ⇒ Object (readonly)

Returns the value of attribute current_token_value.



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# File 'lib/sparkql/lexer.rb', line 8

def current_token_value
  @current_token_value
end

#last_field ⇒ Object (readonly)

Returns the value of attribute last_field.



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# File 'lib/sparkql/lexer.rb', line 8

def last_field
  @last_field
end

#level ⇒ Object

Returns the value of attribute level.



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# File 'lib/sparkql/lexer.rb', line 6

def level
  @level
end

#token_index ⇒ Object (readonly)

Returns the value of attribute token_index.



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# File 'lib/sparkql/lexer.rb', line 8

def token_index
  @token_index
end

Instance Method Details

#check_keywords(value) ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 93

def check_keywords(value)
  result = check_reserved_words(value)
  if result.first == :UNKNOWN
    result = [:KEYWORD,value]
  end
  result
end

#check_reserved_words(value) ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 69

def check_reserved_words(value)
  u_value = value.capitalize
  if OPERATORS.include?(u_value)
    [:OPERATOR,u_value]
  elsif RANGE_OPERATOR == u_value
    [:RANGE_OPERATOR,u_value]
  elsif CONJUNCTIONS.include?(u_value)
    [:CONJUNCTION,u_value]
  elsif UNARY_CONJUNCTIONS.include?(u_value)
    [:UNARY_CONJUNCTION,u_value]
  else
    [:UNKNOWN, "ERROR: '#{self.string}'"]
  end
end

#check_standard_fields(value) ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 84

def check_standard_fields(value)
  result = check_reserved_words(value)
  if result.first == :UNKNOWN
    @last_field = value
    result = [:STANDARD_FIELD,value]
  end
  result
end

#leveldown ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 106

def leveldown
  @level -= 1
end

#levelup ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 101

def levelup
  @level += 1
  @block_group_identifier += 1
end

#literal(symbol, value) ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 110

def literal(symbol, value)
  node = {
    :type => symbol.to_s.downcase.to_sym,
    :value => value
  }
  [symbol, node]
end

#shift ⇒ Object

Lookup the next matching token

TODO the old implementation did value type detection conversion at a later date, we can perform this at parse time if we want!!!!



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# File 'lib/sparkql/lexer.rb', line 22

def shift
  @token_index = self.pos

  token = case
    when @current_token_value = scan(SPACE)
      [:SPACE, @current_token_value]
    when @current_token_value = scan(LPAREN)
      levelup
      [:LPAREN, @current_token_value]
    when @current_token_value = scan(RPAREN)
      # leveldown: do this after parsing group
      [:RPAREN, @current_token_value]
    when @current_token_value = scan(/\,/)
      [:COMMA,@current_token_value]
    when @current_token_value = scan(NULL)
      literal :NULL, "NULL"
    when @current_token_value = scan(STANDARD_FIELD)
      check_standard_fields(@current_token_value)
    when @current_token_value = scan(DATETIME)
      literal :DATETIME, @current_token_value
    when @current_token_value = scan(DATE)
      literal :DATE, @current_token_value
    when @current_token_value = scan(TIME)
      literal :TIME, @current_token_value
    when @current_token_value = scan(DECIMAL)
      literal :DECIMAL, @current_token_value
    when @current_token_value = scan(INTEGER)
      literal :INTEGER, @current_token_value
    when @current_token_value = scan(/\-/)
      [:UMINUS, @current_token_value]
    when @current_token_value = scan(CHARACTER)
      literal :CHARACTER, @current_token_value
    when @current_token_value = scan(BOOLEAN)
      literal :BOOLEAN, @current_token_value
    when @current_token_value = scan(KEYWORD)
      check_keywords(@current_token_value)
    when @current_token_value = scan(CUSTOM_FIELD)
      [:CUSTOM_FIELD,@current_token_value]
    when eos?
      [false, false] # end of file, \Z don't work with StringScanner
    else
      [:UNKNOWN, "ERROR: '#{self.string}'"]
  end

  token.freeze
end