module Encoding

Encoding.escape("hello world!")
# => "hello%20world%21"

Encoding.escape("café")
# => "caf%C3%A9"

parameter　string　String

The string to escape.

returns　String

The escaped string.

def self.escape(string, encoding = string.encoding)
	string.b.gsub(/([^a-zA-Z0-9_.\-]+)/) do |m|
		"%" + m.unpack("H2" * m.bytesize).join("%").upcase
	end.force_encoding(encoding)
end

Encoding.unescape("hello%20world%21")
# => "hello world!"

Encoding.unescape("caf%C3%A9")
# => "café"

parameter　string　String

The string to unescape.

returns　String

The unescaped string.

def self.unescape(string, encoding = string.encoding)
	string.b.gsub(/%(\h\h)/) do |hex|
		Integer($1, 16).chr
	end.force_encoding(encoding)
end

Encoding.unescape_path("hello%20world")     # => "hello world"
Encoding.unescape_path("safe%2Fname")       # => "safe%2Fname" (%2F not decoded)
Encoding.unescape_path("name%5Cfile")       # => "name%5Cfile" (%5C not decoded)

parameter　string　String

The path component to unescape.

returns　String

The unescaped string with separators still encoded.

def self.unescape_path(string, encoding = string.encoding)
	string.b.gsub(/%(\h\h)/) do |hex|
		byte = Integer($1, 16)
		char = byte.chr
		
		# Don't decode forward slash (0x2F) or backslash (0x5C)
		if byte == 0x2F || byte == 0x5C
			hex  # Keep as %2F or %5C
		else
			char
		end
	end.force_encoding(encoding)
end

Encoding.escape_path("/documents/my reports/summary.pdf")
# => "/documents/my%20reports/summary.pdf"

parameter　path　String

The path to escape.

returns　String

The escaped path.

def self.escape_path(path)
	encoding = path.encoding
	path.b.gsub(NON_PATH_CHARACTER_PATTERN) do |m|
		"%" + m.unpack("H2" * m.bytesize).join("%").upcase
	end.force_encoding(encoding)
end

parameter　fragment　String

The fragment to escape.

returns　String

The escaped fragment.

def self.escape_fragment(fragment)
	encoding = fragment.encoding
	fragment.b.gsub(NON_FRAGMENT_CHARACTER_PATTERN) do |m|
		"%" + m.unpack("H2" * m.bytesize).join("%").upcase
	end.force_encoding(encoding)
end

Encoding.encode({"name" => "Alice", "age" => "30"})
# => "name=Alice&age=30"

Encoding.encode({"user" => {"name" => "Alice", "role" => "admin"}})
# => "user[name]=Alice&user[role]=admin"

parameter　value　Hash | Array | Nil

The value to encode.

parameter　prefix　String

The prefix to use for keys.

def self.encode(value, prefix = nil)
	case value
	when Array
		return value.map {|v|
			self.encode(v, "#{prefix}[]")
		}.join("&")
	when Hash
		return value.map {|k, v|
			self.encode(v, prefix ? "#{prefix}[#{escape(k.to_s)}]" : escape(k.to_s))
		}.reject(&:empty?).join("&")
	when nil
		return prefix
	else
		raise ArgumentError, "value must be a Hash" if prefix.nil?
		
		return "#{prefix}=#{escape(value.to_s)}"
	end
end

yields　{|key, value| ...}

parameter　key　String

The unescaped key.

parameter　value　String

The unescaped key.

def self.scan(string)
	string.split("&") do |assignment|
		next if assignment.empty?
		
		key, value = assignment.split("=", 2)
		
		yield unescape(key), value.nil? ? value : unescape(value)
	end
end

parameter　name　String

The key to split.

returns　Array(String)

The parts of the key.

def self.split(name)
	name.scan(/([^\[]+)|(?:\[(.*?)\])/)&.tap do |parts|
		parts.flatten!
		parts.compact!
	end
end

# Query: items[][name]=a&items[][value]=1&items[][name]=b&items[][value]=2
# When "name" appears again, it creates a new array element
# Result: {"items" => [{"name" => "a", "value" => "1"}, {"name" => "b", "value" => "2"}]}

parameter　keys　Array(String)

The parts of the key.

parameter　value　Object

The value to assign.

parameter　parent　Hash

The parent hash.

def self.assign(keys, value, parent)
	top, *middle = keys
	
	middle.each_with_index do |key, index|
		if key.nil? or key.empty?
			# Array element (e.g., items[]):
			parent = (parent[top] ||= Array.new)
			top = parent.size
			
			# Check if we should reuse the last array element or create a new one. If there's a nested key coming next, and the last array element already has that key, then we need a new array element. Otherwise, add to the existing one.
			if nested = middle[index+1] and last = parent.last
				# If the last element doesn't include the nested key, reuse it (decrement index).
				# If it does include the key, keep current index (creates new element).
				top -= 1 unless last.include?(nested)
			end
		else
			# Hash key (e.g., user[name]):
			parent = (parent[top] ||= Hash.new)
			top = key
		end
	end
	
	parent[top] = value
end

Encoding.decode("name=Alice&age=30")
# => {"name" => "Alice", "age" => "30"}

Encoding.decode("user[name]=Alice&user[role]=admin")
# => {"user" => {"name" => "Alice", "role" => "admin"}}

parameter　string　String

The query string to decode.

parameter　maximum　Integer

The maximum number of keys in a path.

parameter　symbolize_keys　Boolean

Whether to symbolize keys.

returns　Hash

The decoded query string.

def self.decode(string, maximum = 8, symbolize_keys: false)
	parameters = {}
	
	self.scan(string) do |name, value|
		keys = self.split(name)
		
		if keys.empty?
			raise ArgumentError, "Invalid key path: #{name.inspect}!"
		end
		
		if keys.size > maximum
			raise ArgumentError, "Key length exceeded limit!"
		end
		
		if symbolize_keys
			keys.collect!{|key| key.empty? ? nil : key.to_sym}
		end
		
		self.assign(keys, value, parameters)
	end
	
	return parameters
end