Class: LangScan::EasyScanner

Inherits:
Object
  • Object
show all
Defined in:
lib/langscan/_easyscanner.rb

Instance Method Summary collapse

Constructor Details

#initialize(pattern, types, keywords) ⇒ EasyScanner

Returns a new instance of EasyScanner.



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# File 'lib/langscan/_easyscanner.rb', line 16

def initialize(pattern, types, keywords)
  @pattern = pattern

  # build regexp
  regexp = "(\n)|" + @pattern.map {|v| "(" + v[1] + ")"}.join("|")
  @regexp = Regexp.new(regexp)

  # build type hash
  @type = {}
  types.each {|k| @type[k] = true }

  # build keyword hash
  @keyword = {}
  keywords.each {|k| @keyword[k] = true }
end

Instance Method Details

#scan(input, &block) ⇒ Object 



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# File 'lib/langscan/_easyscanner.rb', line 32

def scan(input, &block)
  lineno = 0
  offset = 0
  while match = @regexp.match(input[offset..-1])
    if match[1]
      # newline
      lineno += 1
      offset += match.end(0)
    else
      for i in 2..match.size-1
        if match[i]
          type = @pattern[i-2][0]
          byteno = offset + match.begin(0)
          if @pattern[i-2][2]
            # pattern with terminator
            start = offset + match.end(0)
            end_match = input[start..-1].match(@pattern[i-2][2])
            if end_match
              offset = start + end_match.end(0)
            else
              # not terminated! what should we do?
              offset = start
            end
          else
            # simple pattern
            offset += match.end(0)
          end
          text = input[byteno..offset-1]
          if type == :ident
            case true
            when @type[text]
              type = :type
            when @keyword[text]
              type = :keyword
            end
          end
          yield(Fragment.new(type, text, lineno, byteno))
          lineno += text.count("\n")
          break
        end
      end
    end
  end
end