`module Encoding`

Helpers for encoding and decoding URL components.

Nested

System

Definitions

`def self.escape(string, encoding = string.encoding)`

Escapes a string using percent encoding, e.g. a b -> a%20b.

Example: Escape spaces and special characters.

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

Example: Escape unicode characters.

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

Signature

parameter　string　String: The string to escape.
returns　String: The escaped string.

Implementation

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

`def self.unescape(string, encoding = string.encoding)`

Unescapes a percent encoded string, e.g. a%20b -> a b.

Example: Unescape spaces and special characters.

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

Example: Unescape unicode characters.

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

Signature

parameter　string　String: The string to unescape.
returns　String: The unescaped string.
raises　ArgumentError: If the string contains malformed percent encoding.

Implementation

def self.unescape(string, encoding = string.encoding)
	string.b.gsub(/%([0-9A-Fa-f]{2})?/) do
		unless hexadecimal = $1
			raise ArgumentError, "String contains malformed percent encoding!"
		end
		
		Integer(hexadecimal, 16).chr
	end.force_encoding(encoding)
end

`NON_FRAGMENT_CHARACTER_PATTERN = /([^a-zA-Z0-9_\-\.~!$&'()*+,;=:@\/\?]+)/.freeze`

Matches characters that are not allowed in a URI fragment. According to RFC 3986 Section 3.5, a valid fragment consists of pchar / "/" / "?" characters.

`def self.escape_fragment(fragment)`

Escapes non-fragment characters using percent encoding. According to RFC 3986 Section 3.5, fragments can contain pchar / "/" / "?" characters.

Signature

parameter　fragment　String: The fragment to escape.
returns　String: The escaped fragment.

Implementation

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

`def self.encode(value, prefix = nil)`

Encodes a hash or array into a query string. This method is used to encode query parameters in a URL. For example, {"a" => 1, "b" => 2} is encoded as a=1&b=2.

Example: Encode simple parameters.

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

Example: Encode nested parameters.

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

Signature

parameter　value　Hash | Array | Nil: The value to encode.
parameter　prefix　String: The prefix to use for keys.

Implementation

def self.encode(value, prefix = nil)
	case value
	when Array
		return value.map do |v|
			self.encode(v, "#{prefix}[]")
		end.join("&")
	when Hash
		return value.map do |k, v|
			self.encode(v, prefix ? "#{prefix}[#{escape(k.to_s)}]" : escape(k.to_s))
		end.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

`def self.scan(string)`

Scan a string for URL-encoded key/value pairs.

Signature

yields　{|key, value| ...}

parameter　key　String: The unescaped key.
parameter　value　String: The unescaped key.

Implementation

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

`def self.split(name)`

Split a key into parts, e.g. a[b][c] -> ["a", "b", "c"].

Signature

parameter　name　String: The key to split.
returns　Array(String): The parts of the key.

Implementation

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

`def self.assign(keys, value, parent)`

Assign a value to a nested hash.

This method handles building nested data structures from query string parameters, including arrays of objects. When processing array elements (empty key like []), it intelligently decides whether to add to the last array element or create a new one.

Example: Building an array of objects.

# 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"}]}

Signature

parameter　keys　Array(String): The parts of the key.
parameter　value　Object: The value to assign.
parameter　parent　Hash: The parent hash.

Implementation

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

`def self.decode(string, maximum = 8, symbolize_keys: false)`

Decode a URL-encoded query string into a hash.

Example: Decode simple parameters.

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

Example: Decode nested parameters.

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

Signature

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.

Implementation

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

`def self.decode_www_form(string, maximum = 8, symbolize_keys: false)`

Decode an application/x-www-form-urlencoded string into a hash. In addition to percent encoding, this format represents spaces using +.

Signature

parameter　string　String: The form-encoded 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 form values.

Implementation

def self.decode_www_form(string, maximum = 8, symbolize_keys: false)
	return self.decode(string.gsub("+", "%20"), maximum, symbolize_keys: symbolize_keys)
end