require 'strscan' module JSON module Pure # This class implements the JSON parser that is used to parse a JSON string # into a Ruby data structure. class Parser < StringScanner STRING = /" ((?:[^\x0-\x1f"\\] | \\["\\\/bfnrt] | \\u[0-9a-fA-F]{4} | \\[\x20-\xff])*) "/nx INTEGER = /(-?0|-?[1-9]\d*)/ FLOAT = /(-? (?:0|[1-9]\d*) (?: \.\d+(?i:e[+-]?\d+) | \.\d+ | (?i:e[+-]?\d+) ) )/x NAN = /NaN/ INFINITY = /Infinity/ MINUS_INFINITY = /-Infinity/ OBJECT_OPEN = /\{/ OBJECT_CLOSE = /\}/ ARRAY_OPEN = /\[/ ARRAY_CLOSE = /\]/ PAIR_DELIMITER = /:/ COLLECTION_DELIMITER = /,/ TRUE = /true/ FALSE = /false/ NULL = /null/ IGNORE = %r( (?: //[^\n\r]*[\n\r]| # line comments /\* # c-style comments (?: [^*/]| # normal chars /[^*]| # slashes that do not start a nested comment \*[^/]| # asterisks that do not end this comment /(?=\*/) # single slash before this comment's end )* \*/ # the End of this comment |[ \t\r\n]+ # whitespaces: space, horicontal tab, lf, cr )+ )mx UNPARSED = Object.new # Creates a new JSON::Pure::Parser instance for the string _source_. # # It will be configured by the _opts_ hash. _opts_ can have the following # keys: # * *max_nesting*: The maximum depth of nesting allowed in the parsed data # structures. Disable depth checking with :max_nesting => false|nil|0, # it defaults to 19. # * *allow_nan*: If set to true, allow NaN, Infinity and -Infinity in # defiance of RFC 4627 to be parsed by the Parser. This option defaults # to false. # * *create_additions*: If set to false, the Parser doesn't create # additions even if a matchin class and create_id was found. This option # defaults to true. def initialize(source, opts = {}) super if !opts.key?(:max_nesting) # defaults to 19 @max_nesting = 19 elsif opts[:max_nesting] @max_nesting = opts[:max_nesting] else @max_nesting = 0 end @allow_nan = !!opts[:allow_nan] ca = true ca = opts[:create_additions] if opts.key?(:create_additions) @create_id = ca ? JSON.create_id : nil end alias source string # Parses the current JSON string _source_ and returns the complete data # structure as a result. def parse reset obj = nil until eos? case when scan(OBJECT_OPEN) obj and raise ParserError, "source '#{peek(20)}' not in JSON!" @current_nesting = 1 obj = parse_object when scan(ARRAY_OPEN) obj and raise ParserError, "source '#{peek(20)}' not in JSON!" @current_nesting = 1 obj = parse_array when skip(IGNORE) ; else raise ParserError, "source '#{peek(20)}' not in JSON!" end end obj or raise ParserError, "source did not contain any JSON!" obj end private # Unescape characters in strings. UNESCAPE_MAP = Hash.new { |h, k| h[k] = k.chr } UNESCAPE_MAP.update({ ?" => '"', ?\\ => '\\', ?/ => '/', ?b => "\b", ?f => "\f", ?n => "\n", ?r => "\r", ?t => "\t", ?u => nil, }) def parse_string if scan(STRING) return '' if self[1].empty? self[1].gsub(%r((?:\\[\\bfnrt"/]|(?:\\u(?:[A-Fa-f\d]{4}))+|\\[\x20-\xff]))n) do |c| if u = UNESCAPE_MAP[$&[1]] u else # \uXXXX bytes = '' i = 0 while c[6 * i] == ?\\ && c[6 * i + 1] == ?u bytes << c[6 * i + 2, 2].to_i(16) << c[6 * i + 4, 2].to_i(16) i += 1 end JSON::UTF16toUTF8.iconv(bytes) end end else UNPARSED end rescue Iconv::Failure => e raise GeneratorError, "Caught #{e.class}: #{e}" end def parse_value case when scan(FLOAT) Float(self[1]) when scan(INTEGER) Integer(self[1]) when scan(TRUE) true when scan(FALSE) false when scan(NULL) nil when (string = parse_string) != UNPARSED string when scan(ARRAY_OPEN) @current_nesting += 1 ary = parse_array @current_nesting -= 1 ary when scan(OBJECT_OPEN) @current_nesting += 1 obj = parse_object @current_nesting -= 1 obj when @allow_nan && scan(NAN) NaN when @allow_nan && scan(INFINITY) Infinity when @allow_nan && scan(MINUS_INFINITY) MinusInfinity else UNPARSED end end def parse_array raise NestingError, "nesting of #@current_nesting is to deep" if @max_nesting.nonzero? && @current_nesting > @max_nesting result = [] delim = false until eos? case when (value = parse_value) != UNPARSED delim = false result << value skip(IGNORE) if scan(COLLECTION_DELIMITER) delim = true elsif match?(ARRAY_CLOSE) ; else raise ParserError, "expected ',' or ']' in array at '#{peek(20)}'!" end when scan(ARRAY_CLOSE) if delim raise ParserError, "expected next element in array at '#{peek(20)}'!" end break when skip(IGNORE) ; else raise ParserError, "unexpected token in array at '#{peek(20)}'!" end end result end def parse_object raise NestingError, "nesting of #@current_nesting is to deep" if @max_nesting.nonzero? && @current_nesting > @max_nesting result = {} delim = false until eos? case when (string = parse_string) != UNPARSED skip(IGNORE) unless scan(PAIR_DELIMITER) raise ParserError, "expected ':' in object at '#{peek(20)}'!" end skip(IGNORE) unless (value = parse_value).equal? UNPARSED result[string] = value delim = false skip(IGNORE) if scan(COLLECTION_DELIMITER) delim = true elsif match?(OBJECT_CLOSE) ; else raise ParserError, "expected ',' or '}' in object at '#{peek(20)}'!" end else raise ParserError, "expected value in object at '#{peek(20)}'!" end when scan(OBJECT_CLOSE) if delim raise ParserError, "expected next name, value pair in object at '#{peek(20)}'!" end if @create_id and klassname = result[@create_id] klass = JSON.deep_const_get klassname break unless klass and klass.json_creatable? result = klass.json_create(result) end break when skip(IGNORE) ; else raise ParserError, "unexpected token in object at '#{peek(20)}'!" end end result end end end end