Class: ANTLR3::AST::Wizard::PatternLexer

Inherits:
Object
  • Object
show all
Includes:
Constants
Defined in:
lib/antlr3/tree/wizard.rb

Overview

A class that is used internally by AST::Wizard to tokenize tree patterns

Constant Summary collapse

PATTERNS = 
[ 
  [ :space, /\s+/ ],
  [ :identifier, /[a-z_]\w*/i ],
  [ :open, /\(/ ],
  [ :close, /\)/ ],
  [ :percent, /%/ ],
  [ :colon, /:/ ],
  [ :dot, /\./ ],
  [ :argument, /\[((?:[^\[\]\\]|\\\[|\\\]|\\.)*?)\]/ ]
]

Constants included from Constants

Constants::BUILT_IN_TOKEN_NAMES, Constants::DEFAULT, Constants::DOWN, Constants::EOF, Constants::EOF_TOKEN, Constants::EOR_TOKEN_TYPE, Constants::HIDDEN, Constants::INVALID, Constants::INVALID_NODE, Constants::INVALID_TOKEN, Constants::MEMO_RULE_FAILED, Constants::MEMO_RULE_UNKNOWN, Constants::MIN_TOKEN_TYPE, Constants::SKIP_TOKEN, Constants::UP

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pattern) ⇒ PatternLexer

Returns a new instance of PatternLexer.



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# File 'lib/antlr3/tree/wizard.rb', line 145

def initialize( pattern )
  @pattern = pattern.to_s
  @scanner = StringScanner.new( pattern )
  @text = ''
  @error = false
end

Instance Attribute Details

#error ⇒ Object (readonly) Also known as: error?

Returns the value of attribute error.



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# File 'lib/antlr3/tree/wizard.rb', line 144

def error
  @error
end

#pattern ⇒ Object (readonly)

Returns the value of attribute pattern.



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# File 'lib/antlr3/tree/wizard.rb', line 144

def pattern
  @pattern
end

#text ⇒ Object (readonly)

Returns the value of attribute text.



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# File 'lib/antlr3/tree/wizard.rb', line 144

def text
  @text
end

Instance Method Details

#next_token ⇒ Object 



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# File 'lib/antlr3/tree/wizard.rb', line 152

def next_token
  begin
    @scanner.eos? and return EOF
    
    type, = PATTERNS.find do |type, pattern|
      @scanner.scan( pattern )
    end
    
    case type
    when nil
      type, @text, @error = EOF, '', true
      break
    when :identifier then @text = @scanner.matched
    when :argument
      # remove escapes from \] sequences in the text argument
      ( @text = @scanner[ 1 ] ).gsub!( /\\(?=[\[\]])/, '' )
    end
  end while type == :space
  
  return type
end