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 6

def initialize(node)
  @_current_node = node
end

Instance Method Details

#parse(exp) ⇒ Object 



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# File 'lib/jsonpath/parser.rb', line 10

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 24

def parse_exp(exp)
  exp = exp.gsub(/@/, '').gsub(/[\(\)]/, '')
  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(/\['\w+'\]+/)
      elements << t.gsub(/\[|\]|'|\s+/, '')
    elsif t = scanner.scan(/\s+[<>=][<>=]?\s+?/)
      operator = t
    elsif t = scanner.scan(/(\s+)?'?(\w+)?[.,]?(\w+)?'?(\s+)?/) # @TODO: At this point I should trim somewhere...
      operand = t.delete("'").strip
    elsif t = scanner.scan(/.*/)
      raise "Could not process symbol: #{t}"
    end
  end
  el = dig(elements, @_current_node)
  return false unless el
  return true if operator.nil? && el
  operand = operand.to_f if operand.to_i.to_s == operand || operand.to_f.to_s == operand
  el.send(operator.strip, operand)
end