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 => {})
  @warnings = []
  @text_type = :text
end

Instance Attribute Details

#optionsObject (readonly)

The hash with the parsing options.



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

def options
  @options
end

#rootObject (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

#sourceObject (readonly)

The original source string.



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

def source
  @source
end

#warningsObject (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 67

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 91

def adapt_source(source)
  if source.respond_to?(:encode)
    if !source.valid_encoding?
      raise "The source text contains invalid characters for the used encoding #{source.encoding}"
    end
    source = source.encode('UTF-8')
  end
  source.gsub(/\r\n?/, "\n").chomp + "\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 103

def add_text(text, tree = @tree, type = @text_type)
  last = tree.children.last
  if last && last.type == type
    last.value << text
  elsif !text.empty?
    tree.children << Element.new(type, text, nil, :location => (last && last.options[:location] || tree.options[: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 114

def extract_string(range, strscan)
  result = nil
  if strscan.string.respond_to?(:encoding)
    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
  else
    result = strscan.string[range]
  end
  result
end

#parseObject

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 79

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 84

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