Class: JsonBuilder::JsonBase

Inherits:
BlankSlate show all
Defined in:
lib/json_builder/jsonbase.rb

Overview

JsonBase is a base class for building XML builders. See JsonBuilder::JsonMarkup and JsonBuilder::JsonEvents for examples.

Direct Known Subclasses

JsonMarkup

Instance Method Summary collapse

Methods inherited from BlankSlate

find_hidden_method, hide, reveal

Constructor Details

#initialize(encoding = 'utf-8') ⇒ JsonBase

Create an XML markup builder.

out

Object receiving the markup. out must respond to <<.

indent

Number of spaces used for indentation (0 implies no indentation and no line breaks).

initial

Level of initial indentation.

encoding

When encoding and $KCODE are set to ‘utf-8’ characters aren’t converted to character entities in the output stream.



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# File 'lib/json_builder/jsonbase.rb', line 22

def initialize(encoding='utf-8')
  @encoding = encoding.downcase
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(sym, *args, &block) ⇒ Object

Create XML markup based on the name of the method. This method is never invoked directly, but is called for each markup method in the markup block.



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# File 'lib/json_builder/jsonbase.rb', line 36

def method_missing(sym, *args, &block)
  text = nil
  sym = "#{sym}:#{args.shift}" if args.first.kind_of?(Symbol)
  
  @target = '{' if @target.length == 0
  @target.chop! if @target.last == '}'
  
  args.each do |arg|
    case arg
    when Hash
      attrs ||= {}
      attrs.merge!(arg)
    else
      text = arg
    end
  end
  
  if block
    raise ArgumentError, "JsonMarkup cannot mix a text argument with a block" unless text.nil?
    
    _start_tag(sym)
    block.call(self)
    _end_tag
  elsif text.nil?
    _start_tag(sym)
  else
    _start_attr(sym)
    text! text
    _end_tag
  end
  
  @target.gsub(/,(\}+)$/, '\1')
end

Instance Method Details

#<<(text) ⇒ Object

Append text to the output target without escaping any markup. May be used within the markup brackets as:

builder.p { |x| x << "<br/>HI" }   #=>  <p><br/>HI</p>

This is useful when using non-builder enabled software that generates strings. Just insert the string directly into the builder without changing the inserted markup.

It is also useful for stacking builder objects. Builders only use << to append to the target, so by supporting this method/operation builders can use other builders as their targets.



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# File 'lib/json_builder/jsonbase.rb', line 100

def <<(text)
  _text(text)
end

#nil? ⇒ Boolean

For some reason, nil? is sent to the JsonMarkup object. If nil? is not defined and method_missing is invoked, some strange kind of recursion happens. Since nil? won’t ever be an XML tag, it is pretty safe to define it here. (Note: this is an example of cargo cult programming, cf. fishbowl.pastiche.org/2004/10/13/cargo_cult_programming).

Returns:

  • (Boolean) 


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# File 'lib/json_builder/jsonbase.rb', line 110

def nil?
  false
end

#tag!(sym, *args, &block) ⇒ Object

Create a tag named sym. Other than the first argument which is the tag name, the arguments are the same as the tags implemented via method_missing.



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# File 'lib/json_builder/jsonbase.rb', line 29

def tag!(sym, *args, &block)
  method_missing(sym.to_sym, args, &block)
end

#text!(text) ⇒ Object

Append text to the output target. Escape any markup. May be used within the markup brackets as:

builder.p { |b| b.br; b.text! "HI" }   #=>  <p><br/>HI</p>



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# File 'lib/json_builder/jsonbase.rb', line 74

def text!(text)
  value = case text
    when TrueClass then 'true'
    when FalseClass then 'false'
    when NilClass then 'undefined'
    when Float then text.to_s
    when Fixnum then text.to_s
    else "\"#{_escape(text)}\""
  end
  
  _text(value)
end