Class: IMW::Parsers::LineParser

Inherits:
Object
  • Object
show all
Defined in:
lib/imw/parsers/line_parser.rb

Overview

This is an abstract class for a line-oriented parser intended to read and emit lines sequentially from a file.

To leverage the functionality of this class, subclass it and define a parse_line method.

Direct Known Subclasses

RegexpParser

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ LineParser

If called with the option :skip_first then skip the corresponding number of lines at the beginning of the file when parsing.



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# File 'lib/imw/parsers/line_parser.rb', line 21

def initialize options={}
  @skip_first = options[:skip_first] || 0
  @klass      = options[:of]         || options[:klass]
end

Instance Attribute Details

#klass ⇒ Object

The class to parse each line into. The new method of this class must accept a hash.



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# File 'lib/imw/parsers/line_parser.rb', line 16

def klass
  @klass
end

#skip_first ⇒ Object

The number of lines to skip on each file parsed.



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# File 'lib/imw/parsers/line_parser.rb', line 12

def skip_first
  @skip_first
end

Instance Method Details

#parse!(file, options = {}, &block) ⇒ Object

Parse the given file. If the option :lines is passed in then only parse that many lines. If given a block then yield the result of each line to the block; else just return an array of results.

If this parser has a klass attribute then each parsed line will first be turned into an instance of that class (the class must accept a hash of values in its initializer).



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# File 'lib/imw/parsers/line_parser.rb', line 34

def parse! file, options={}, &block
  skip_lines!(file)
  if options[:lines]
    case
    when klass && block_given?
      options[:lines].times do
        yield klass.new(parse_line(file.readline))
      end
    when block_given?
      options[:lines].times do
        yield parse_line(file.readline)
      end
    when klass
      options[:lines].times do
        klass.new(parse_line(file.readline))
      end
    else
      options[:lines].times.map do
        parse_line(file.readline)
      end
    end
  else
    case
    when klass && block_given?
      file.each do |line|
        yield klass.new(parse_line(line))
      end
    when block_given?
      file.each do |line|
        yield parse_line(line)
      end
    when klass
      file.map do |line|
        klass.new(parse_line(line))
      end
    else
      file.map do |line|
        parse_line(line)
      end
    end
  end
end

#parse_line(line) ⇒ Object

Raises:



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# File 'lib/imw/parsers/line_parser.rb', line 77

def parse_line line
  raise IMW::NotImplementedError.new("Subclass the LineParser and redefine this method to create a true parser.")
end