Class: Kramdown::Parser::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/kramdown/parser/base.rb

Overview

Base class for parsers

This class serves as base class for parsers. It provides common methods that can/should be used by all parsers, especially by those using StringScanner(Kramdown) for parsing.

A parser object is used as a throw-away object, i.e. it is only used for storing the needed state information during parsing. Therefore one can’t instantiate a parser object directly but only use the Base::parse method.

Implementing a parser

Implementing a new parser is rather easy: just derive a new class from this class and put it in the Kramdown::Parser module – the latter is needed so that the auto-detection of the new parser works correctly. Then you need to implement the #parse method which has to contain the parsing code.

Have a look at the Base::parse, Base::new and Base#parse methods for additional information!

Direct Known Subclasses

Html, Kramdown

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source, options) ⇒ Base

Initialize the parser object with the source string and the parsing options.

The @root element, the @warnings array and @text_type (specifies the default type for newly created text nodes) are automatically initialized.



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# File 'lib/kramdown/parser/base.rb', line 52

def initialize(source, options)
  @source = source
  @options = Kramdown::Options.merge(options)
  @root = Element.new(:root, nil, nil, encoding: (source.encoding rescue nil), location: 1,
                      options: {}, abbrev_defs: {}, abbrev_attr: {})

  @root.options[:abbrev_defs].default_proc = @root.options[:abbrev_attr].default_proc =
    lambda do |h, k|
      k_mod = k.gsub(/[\s\p{Z}]+/, " ")
      k != k_mod ? h[k_mod] : nil
    end
  @warnings = []
  @text_type = :text
end

Instance Attribute Details

#options ⇒ Object (readonly)

The hash with the parsing options.



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# File 'lib/kramdown/parser/base.rb', line 37

def options
  @options
end

#root ⇒ Object (readonly)

The root element of element tree that is created from the source string.



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# File 'lib/kramdown/parser/base.rb', line 46

def root
  @root
end

#source ⇒ Object (readonly)

The original source string.



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# File 'lib/kramdown/parser/base.rb', line 43

def source
  @source
end

#warnings ⇒ Object (readonly)

The array with the parser warnings.



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# File 'lib/kramdown/parser/base.rb', line 40

def warnings
  @warnings
end

Class Method Details

.parse(source, options = {}) ⇒ Object

Parse the source string into an element tree, possibly using the parsing options, and return the root element of the element tree and an array with warning messages.

Initializes a new instance of the calling class and then calls the #parse method that must be implemented by each subclass.



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# File 'lib/kramdown/parser/base.rb', line 73

def self.parse(source, options = {})
  parser = new(source, options)
  parser.parse
  [parser.root, parser.warnings]
end

Instance Method Details

#adapt_source(source) ⇒ Object

Modify the string source to be usable by the parser (unifies line ending characters to \n and makes sure source ends with a new line character).



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# File 'lib/kramdown/parser/base.rb', line 97

def adapt_source(source)
  unless source.valid_encoding?
    raise "The source text contains invalid characters for the used encoding #{source.encoding}"
  end
  source = source.encode('UTF-8')
  source.gsub!(/\r\n?/, "\n")
  source.chomp!
  source << "\n"
end

#add_text(text, tree = @tree, type = @text_type) ⇒ Object

This helper method adds the given text either to the last element in the tree if it is a type element or creates a new text element with the given type.



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# File 'lib/kramdown/parser/base.rb', line 109

def add_text(text, tree = @tree, type = @text_type)
  last = tree.children.last
  if last && last.type == type
    last.value << text
  elsif !text.empty?
    location = (last && last.options[:location] || tree.options[:location])
    tree.children << Element.new(type, text, nil, location: location)
  end
end

#extract_string(range, strscan) ⇒ Object

Extract the part of the StringScanner strscan backed string specified by the range. This method works correctly under Ruby 1.8 and Ruby 1.9.



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# File 'lib/kramdown/parser/base.rb', line 121

def extract_string(range, strscan)
  result = nil
  begin
    enc = strscan.string.encoding
    strscan.string.force_encoding('ASCII-8BIT')
    result = strscan.string[range].force_encoding(enc)
  ensure
    strscan.string.force_encoding(enc)
  end
  result
end

#parse ⇒ Object

Parse the source string into an element tree.

The parsing code should parse the source provided in @source and build an element tree the root of which should be @root.

This is the only method that has to be implemented by sub-classes!

Raises:

  • (NotImplementedError) 


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# File 'lib/kramdown/parser/base.rb', line 85

def parse
  raise NotImplementedError
end

#warning(text) ⇒ Object

Add the given warning text to the warning array.



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# File 'lib/kramdown/parser/base.rb', line 90

def warning(text)
  @warnings << text
  # TODO: add position information
end