Class: Sparkql::Lexer

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

Constant Summary

Constants included from Token

Token::ADD, Token::BOOLEAN, Token::CHARACTER, Token::CONJUNCTIONS, Token::CUSTOM_FIELD, Token::DATE, Token::DATETIME, Token::DECIMAL, Token::DIV, Token::EQUALITY_OPERATORS, Token::INTEGER, Token::KEYWORD, Token::LPAREN, Token::MOD, Token::MUL, Token::NEWLINE, Token::NULL, Token::OPERATORS, Token::RANGE_OPERATOR, Token::RPAREN, Token::SPACE, Token::STANDARD_FIELD, Token::SUB, 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 99

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 65

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]
  elsif ADD == u_value
    [:ADD, u_value]
  elsif SUB == u_value
    [:SUB, u_value]
  elsif MUL == u_value
    [:MUL, u_value]
  elsif DIV == u_value
    [:DIV, u_value]
  elsif MOD == u_value
    [:MOD, u_value]
  else
    [:UNKNOWN, "ERROR: '#{self.string}'"]
  end
end

#check_standard_fields(value) ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 90

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 112

def leveldown
  @level -= 1
end

#levelup ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 107

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

#literal(symbol, value) ⇒ Object 



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# File 'lib/sparkql/lexer.rb', line 116

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

#shift ⇒ Object

Lookup the next matching token



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# File 'lib/sparkql/lexer.rb', line 19

def shift
  @token_index = self.pos

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

  token.freeze
end