Validate JSON through RegEx

General
1

Because I apparently have a lot of time on my hands (!), I came up with this regular expression to validate JSON.

(?x)

# SUBROUTINES
(?(DEFINE)
	(?<num>-? (?:\\d+\\.)? \\d+ (?:e [-+]? \\d+)?)
	(?<string>" (?:\\\" | [^"])* ")
	(?<key>\\s* (?&string) \\s* : \\s*)
	(?<value>\\s* (?:true | false | null | (?&num) | (?&string)) \\s*)
	(?<struct>
		# Array
		\\s*\\[ (?:
			(?:(?&struct) \\s* | (?&value))
			(?:, (?:(?&struct) \\s* | (?&value)))*
		)? \\] |
		# Dictionary
		\\s*\\{ (?:
			(?&key) (?:(?&struct) \\s* | (?&value))
			(?:, (?&key) (?:(?&struct) \\s* | (?&value)))*
		)? \\}
	) # Struct
)

# MAIN
\\s*          # Capture any leading whitespace
\\K           # Restart the match
(?&struct)   # Match it