Class: Cucumber::TagExpressions::Parser

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

Overview

Ruby tag expression parser

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/cucumber/tag_expressions/parser.rb', line 7

def initialize
  @expressions = []
  @operators = []

  @operator_types = {
    'or'  => { type: :binary_operator,    precedence: 0, assoc: :left },
    'and' => { type: :binary_operator,   precedence: 1, assoc: :left },
    'not' => { type: :unary_operator,   precedence: 2, assoc: :right },
    ')'   => { type: :close_paren,       precedence: -1 },
    '('   => { type: :open_paren,        precedence: 1 }
  }
end

Instance Method Details

#parse(infix_expression) ⇒ Object 



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# File 'lib/cucumber/tag_expressions/parser.rb', line 20

def parse(infix_expression)
  process_tokens!(infix_expression)
  while @operators.any?
    raise 'Syntax error. Unmatched (' if @operators.last == '('
    push_expression(pop(@operators))
  end
  expression = pop(@expressions)
  @expressions.empty? ? expression : raise('Not empty')
end