Class: JsonPath::Parser

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

Overview

Parser parses and evaluates an expression passed to @_current_node.

Instance Method Summary collapse

Constructor Details

#initialize(node) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/jsonpath/parser.rb', line 9

def initialize(node)
  @_current_node = node
end

Instance Method Details

#parse(exp) ⇒ Object 



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# File 'lib/jsonpath/parser.rb', line 13

def parse(exp)
  exps = exp.split(/(&&)|(\|\|)/)
  ret = parse_exp(exps.shift)
  exps.each_with_index do |item, index|
    case item
    when '&&'
      ret &&= parse_exp(exps[index + 1])
    when '||'
      ret ||= parse_exp(exps[index + 1])
    end
  end
  ret
end

#parse_exp(exp) ⇒ Object 



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# File 'lib/jsonpath/parser.rb', line 27

def parse_exp(exp)
  exp = exp.sub(/@/, '').gsub(/^\(/, '').gsub(/\)$/, '').tr('"', '\'').strip
  scanner = StringScanner.new(exp)
  elements = []
  until scanner.eos?
    if scanner.scan(/\./)
      sym = scanner.scan(/\w+/)
      op = scanner.scan(/./)
      num = scanner.scan(/\d+/)
      return @_current_node.send(sym.to_sym).send(op.to_sym, num.to_i)
    end
    if t = scanner.scan(/\['[a-zA-Z@&\*\/\$%\^\?_]+'\]+/)
      elements << t.gsub(/\[|\]|'|\s+/, '')
    elsif t = scanner.scan(/(\s+)?[<>=][=~]?(\s+)?/)
      operator = t
    elsif t = scanner.scan(/(\s+)?'?.*'?(\s+)?/)
      # If we encounter a node which does not contain `'` it means
      #  that we are dealing with a boolean type.
      operand = if t == 'true'
                  true
                elsif t == 'false'
                  false
                else
                  operator.strip == '=~' ? t.to_regexp : t.gsub(%r{^'|'$}, '').strip
                end
    elsif t = scanner.scan(/\/\w+\//)
    elsif t = scanner.scan(/.*/)
      raise "Could not process symbol: #{t}"
    end
  end

  el = if elements.empty?
         @_current_node
       else
         dig(elements, @_current_node)
       end
  return false if el.nil?
  return true if operator.nil? && el

  el = Float(el) rescue el
  operand = Float(operand) rescue operand

  el.__send__(operator.strip, operand)
end