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require 'cgi'
require 'strscan'
module Rack
# Rack middleware for parsing POST/PUT body data into nested parameters
class NestedParams
CONTENT_TYPE = 'CONTENT_TYPE'.freeze
POST_BODY = 'rack.input'.freeze
FORM_INPUT = 'rack.request.form_input'.freeze
FORM_HASH = 'rack.request.form_hash'.freeze
FORM_VARS = 'rack.request.form_vars'.freeze
# supported content type
URL_ENCODED = 'application/x-www-form-urlencoded'.freeze
def initialize(app)
@app = app
end
def call(env)
if form_vars = env[FORM_VARS]
env[FORM_HASH] = parse_query_parameters(form_vars)
elsif env[CONTENT_TYPE] == URL_ENCODED
post_body = env[POST_BODY]
env[FORM_INPUT] = post_body
env[FORM_HASH] = parse_query_parameters(post_body.read)
post_body.rewind if post_body.respond_to?(:rewind)
end
@app.call(env)
end
## the rest is nabbed from Rails ##
def parse_query_parameters(query_string)
return {} if query_string.nil? or query_string.empty?
pairs = query_string.split('&').collect do |chunk|
next if chunk.empty?
key, value = chunk.split('=', 2)
next if key.empty?
value = value.nil? ? nil : CGI.unescape(value)
[ CGI.unescape(key), value ]
end.compact
UrlEncodedPairParser.new(pairs).result
end
class UrlEncodedPairParser < StringScanner
attr_reader :top, :parent, :result
def initialize(pairs = [])
super('')
@result = {}
pairs.each { |key, value| parse(key, value) }
end
KEY_REGEXP = %r{([^\[\]=&]+)}
BRACKETED_KEY_REGEXP = %r{\[([^\[\]=&]+)\]}
# Parse the query string
def parse(key, value)
self.string = key
@top, @parent = result, nil
# First scan the bare key
key = scan(KEY_REGEXP) or return
key = post_key_check(key)
# Then scan as many nestings as present
until eos?
r = scan(BRACKETED_KEY_REGEXP) or return
key = self[1]
key = post_key_check(key)
end
bind(key, value)
end
private
# After we see a key, we must look ahead to determine our next action. Cases:
#
# [] follows the key. Then the value must be an array.
# = follows the key. (A value comes next)
# & or the end of string follows the key. Then the key is a flag.
# otherwise, a hash follows the key.
def post_key_check(key)
if scan(/\[\]/) # a[b][] indicates that b is an array
container(key, Array)
nil
elsif check(/\[[^\]]/) # a[b] indicates that a is a hash
container(key, Hash)
nil
else # End of key? We do nothing.
key
end
end
# Add a container to the stack.
def container(key, klass)
type_conflict! klass, top[key] if top.is_a?(Hash) && top.key?(key) && ! top[key].is_a?(klass)
value = bind(key, klass.new)
type_conflict! klass, value unless value.is_a?(klass)
push(value)
end
# Push a value onto the 'stack', which is actually only the top 2 items.
def push(value)
@parent, @top = @top, value
end
# Bind a key (which may be nil for items in an array) to the provided value.
def bind(key, value)
if top.is_a? Array
if key
if top[-1].is_a?(Hash) && ! top[-1].key?(key)
top[-1][key] = value
else
top << {key => value}
end
push top.last
return top[key]
else
top << value
return value
end
elsif top.is_a? Hash
key = CGI.unescape(key)
parent << (@top = {}) if top.key?(key) && parent.is_a?(Array)
top[key] ||= value
return top[key]
else
raise ArgumentError, "Don't know what to do: top is #{top.inspect}"
end
end
def type_conflict!(klass, value)
raise TypeError, "Conflicting types for parameter containers. Expected an instance of #{klass} but found an instance of #{value.class}. This can be caused by colliding Array and Hash parameters like qs[]=value&qs[key]=value. (The parameters received were #{value.inspect}.)"
end
end
end
end