Class: Syntax::Tokenizer

Inherits:
Object
  • Object
show all
Defined in:
lib/syntax/common.rb

Overview

The base class of all tokenizers. It sets up the scanner and manages the looping until all tokens have been extracted. It also provides convenience methods to make sure adjacent tokens of identical groups are returned as a single token.

Direct Known Subclasses

Ruby, XML, YAML

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.delegate(sym) ⇒ Object

A convenience for delegating method calls to the scanner.



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# File 'lib/syntax/common.rb', line 73

def self.delegate( sym )
  define_method( sym ) { |*a| @text.__send__( sym, *a ) }
end

Instance Method Details

#finish ⇒ Object

Finish tokenizing. This flushes the buffer, yielding any remaining text to the client.



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# File 'lib/syntax/common.rb', line 46

def finish
  start_group nil
  teardown
end

#setup ⇒ Object

Subclasses may override this method to provide implementation-specific setup logic.



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# File 'lib/syntax/common.rb', line 41

def setup
end

#start(text, &block) ⇒ Object

Start tokenizing. This sets up the state in preparation for tokenization, such as creating a new scanner for the text and saving the callback block. The block will be invoked for each token extracted.



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# File 'lib/syntax/common.rb', line 31

def start( text, &block )
  @chunk = ""
  @group = :normal
  @callback = block
  @text = StringScanner.new( text )
  setup
end

#step ⇒ Object

Subclasses must implement this method, which is called for each iteration of the tokenization process. This method may extract multiple tokens.

Raises:

  • (NotImplementedError) 


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# File 'lib/syntax/common.rb', line 58

def step
  raise NotImplementedError, "subclasses must implement #step"
end

#teardown ⇒ Object

Subclasses may override this method to provide implementation-specific teardown logic.



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# File 'lib/syntax/common.rb', line 53

def teardown
end

#tokenize(text, &block) ⇒ Object

Begins tokenizing the given text, calling #step until the text has been exhausted.



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# File 'lib/syntax/common.rb', line 64

def tokenize( text, &block )
  start text, &block
  step until @text.eos?
  finish
end