Class: HtmlConditionalComment::Lexer

Inherits:
Object
  • Object
show all
Defined in:
lib/html-conditional-comment/lexer.rb

Overview

Converts string into array of tokens. Token is an array, first element is symbol representing the token, second element is string value.

Constant Summary collapse

LESS_THAN = 
/lt/i
LESS_THAN_EQUAL = 
/lte/i
GREATER_THAN = 
/gt/i
GREATER_THAN_EQUAL = 
/gte/i
OPEN_PAREN = 
/\(/
CLOSE_PAREN = 
/\)/
NOT = 
/\!/
OR = 
/\|/
AND = 
/\&/
TRUE = 
/true/i
FALSE = 
/false/i
IF_STATEMENT = 
/if/i
ENDIF_STATEMENT = 
/endif/i
OPEN =

Opening statement plus positive look ahead to avoid conflicts with other comments, could also have additional comments before “if”

/<!(\-\-)?[^>]*?\[(?=(end)?if)/
CLOSE =

Closing statement with additional comments after “endif”

/\].*?(\-\-)?>/
WHITE_SPACE = 
/\s+/
FEATURE = 
/[a-z]+/i
VERSION_VECTOR = 
/\d+(\.[\d]+)?/
TOKENS = 
[
  [:if, IF_STATEMENT],
  [:endif, ENDIF_STATEMENT],

  [:paren_open, OPEN_PAREN],
  [:paren_close, CLOSE_PAREN],

  [:operator_less_than_equal, LESS_THAN_EQUAL],
  [:operator_less_than, LESS_THAN],
  [:operator_greater_than_equal, GREATER_THAN_EQUAL],
  [:operator_greater_than, GREATER_THAN],

  [:operator_not, NOT],
  [:operator_or, OR],
  [:operator_and, AND],

  [:boolean_true, TRUE],
  [:boolean_false, FALSE],
  [:feature, FEATURE],
  [:version_vector, VERSION_VECTOR]
]

Instance Method Summary collapse

Constructor Details

#initialize(html_or_comment) ⇒ Lexer

Returns a new instance of Lexer.



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# File 'lib/html-conditional-comment/lexer.rb', line 57

def initialize(html_or_comment)
  @scanner = StringScanner.new(html_or_comment)
end

Instance Method Details

#tokenize ⇒ Object 



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# File 'lib/html-conditional-comment/lexer.rb', line 61

def tokenize()
  tokens = []
  open = false

  #Run until nothing left in string
  until @scanner.eos?()
    #Split between if the conditional comment has been opened or not
    #State will help handle all the other HTML we don't care about
    if open
      @scanner.skip(WHITE_SPACE)
      if token = @scanner.scan(CLOSE)
        open = false
        tokens << [:close, token]
      else
        #Go through token specs and scan and stop on first one
        token = TOKENS.inject(nil) do |previous, spec|
          t = @scanner.scan(spec[1])
          unless t.nil?()
            break [spec[0], t]
          end
        end
        if token
          tokens << token
        else
          raise TokenError.new(@scanner.rest())
        end
      end
    #Closed (not opened) conditional comment
    else
      #Scan till we find an open token, if not done and use the rest
      if match = @scanner.scan_until(OPEN)
        open = true
        #TODO Gross way to get up till scan has succeeded
        match = match.slice(0..-(@scanner.matched.size() + 1))
        tokens << [:html, match] unless match.empty?()
        tokens << [:open, @scanner.matched]
      else
        tokens << [:html, @scanner.rest()] if @scanner.rest?()
        break
      end
    end
  end
  @scanner.reset()

  tokens
end