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File name : token-scanner.rb

Content :# encoding: utf-8 module Crass # Like {Scanner}, but for tokens! class TokenScanner attr_reader :current, :pos, :tokens def initialize(tokens) @tokens = tokens.to_a reset end # Executes the given block, collects all tokens that are consumed during its # execution, and returns them. def collect start = @pos yield @tokens[start...@pos] || [] end # Consumes the next token and returns it, advancing the pointer. Returns # `nil` if there is no next token. def consume @current = @tokens[@pos] @pos += 1 if @current @current end # Returns the next token without consuming it, or `nil` if there is no next # token. def peek @tokens[@pos] end # Reconsumes the current token, moving the pointer back one position. # # http://www.w3.org/TR/2013/WD-css-syntax-3-20130919/#reconsume-the-current-input-token def reconsume @pos -= 1 if @pos > 0 end # Resets the pointer to the first token in the list. def reset @current = nil @pos = 0 end end end

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