# hx/path - path selectors
#
# Copyright (c) 2009-2010 MenTaLguY <mental@rydia.net>
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

module Hx
module Path

module Selector
  def accept_path?(path)
    raise NotImplementedError, "#{self.class}#accept_path? not implemented"
  end

  def literal?
    false
  end

  def |(other)
    Disjunction.build(self, other)
  end

  def &(other)
    Conjunction.build(self, other)
  end

  def ~()
    Negation.build(self)
  end

  def assume_circumfix(prefix, suffix)
    AssumeCircumfix.build(self, prefix, suffix)
  end

  def elide_circumfix(prefix, suffix)
    ElideCircumfix.build(self, prefix, suffix)
  end
end

class All
  include Selector
  def accept_path?(path) ; true ; end
end

ALL = All.new

class Pattern
  include Selector

  def initialize(tokens)
    @is_literal = tokens.size == 1 and String === tokens.first
    @regexp = Regexp.new("^#{tokens.map { |token|
      case token
      when :doublestar; '.*'
      when :star; '[^/]*'
      else; Regexp.quote(token)
      end
    }}$")
  end

  def literal?
    @is_literal
  end

  def accept_path?(path) ; !!(path =~ @regexp) ; end
end

def self.parse_pattern(pattern_string)
  tokens = []
  pattern_string.scan(/(\*\*?|[^*]+)/) do |token,|
    tokens << case token
              when "**"; :doublestar
              when "*"; :star
              else; token
              end
  end
  Pattern.new(tokens)
end

def self.literal(literal_string)
  Pattern.new([literal_string])
end

module Connective
  include Selector

  def initialize(*selectors)
    @selectors = selectors
  end
end

class Conjunction
  include Connective

  def self.build(*selectors)
    if selectors.any? { |s| All === s }
      selectors.reject! { |s| All === s }
      case selectors.size
      when 0; return ALL
      when 1; return selectors.first
      end
    end
    new(*selectors)
  end

  def accept_path?(path)
    @selectors.all? { |s| s.accept_path? path }
  end
end

class Disjunction
  include Connective

  def self.build(*selectors)
    return ALL if selectors.any? { |s| All === s }
    new(*selectors)
  end

  def accept_path?(path)
    @selectors.any? { |s| s.accept_path? path }
  end
end

class Negation
  include Selector

  def self.build(selector)
    new(selector)
  end

  def initialize(selector)
    @selector = selector
  end

  def accept_path?(path)
    not @selector.accept_path?(path)
  end
end

class AssumeCircumfix
  include Selector

  def self.build(selector, prefix, suffix)
    case selector
    when All; ALL
    else; new(selector, prefix, suffix)
    end
  end

  def initialize(selector, prefix, suffix)
    @selector = selector
    @prefix = prefix
    @suffix = suffix
  end

  def accept_path?(path)
    @selector.accept_path?("#{@prefix}#{path}#{@suffix}")
  end
end

def self.make_circumfix_re(prefix, suffix)
  quoted_prefix = Regexp.quote(prefix.to_s)
  quoted_suffix = Regexp.quote(suffix.to_s)
  @circumfix_re = /^#{quoted_prefix}(.*)#{quoted_suffix}$/
end

class ElideCircumfix
  include Selector

  def self.build(selector, prefix, suffix)
    new(selector, prefix, suffix)
  end

  def initialize(selector, prefix, suffix)
    @selector = selector
    @circumfix_re = Path.make_circumfix_re(prefix, suffix)
  end

  def accept_path?(path)
    !!(path =~ @circumfix_re and @selector.accept_path?($1))
  end
end

end
end