module Rack::Utils::OkJson - rack-1.6.4 Documentation

# module Rack::Utils::OkJson

Some parts adapted from golang.org/src/encoding/json/decode.go and golang.org/src/unicode/utf8/utf8.go

### Constants

Spc
Uchar1max
Uchar2max
Uchar3max
Ucharerr
Umask2
Umask3
Umask4
Umaskx
Unesc
Upstream
Ustrerr
Usurr1
Usurr2
Usurr3
Usurrself
Utag2
Utag3
Utag4
Utag5
Utagx

### Public Instance Methods

decode(s) click to toggle source

Decodes a json document in string s and returns the corresponding ruby value. String s must be valid UTF-8. If you have a string in some other encoding, convert it first.

String values in the resulting structure will be UTF-8.

    # File lib/rack/utils/okjson.rb, line 42
    def decode(s)
      ts = lex(s)
      v, ts = textparse(ts)
      if ts.length > 0
        raise Error, 'trailing garbage'
      end
      v
    end

encode(x) click to toggle source

Encodes x into a json text. It may contain only Array, Hash, String, Numeric, true, false, nil. (Note, this list excludes Symbol.) X itself must be an Array or a Hash. No other value can be encoded, and an error will be raised if x contains any other value, such as Nan, Infinity, Symbol, and Proc, or if a Hash key is not a String. Strings contained in x must be valid UTF-8.

    # File lib/rack/utils/okjson.rb, line 61
    def encode(x)
      case x
      when Hash    then objenc(x)
      when Array   then arrenc(x)
      else
        raise Error, 'root value must be an Array or a Hash'
      end
    end

valenc(x) click to toggle source

    # File lib/rack/utils/okjson.rb, line 71
    def valenc(x)
      case x
      when Hash    then objenc(x)
      when Array   then arrenc(x)
      when String  then strenc(x)
      when Numeric then numenc(x)
      when true    then "true"
      when false   then "false"
      when nil     then "null"
      else
        raise Error, "cannot encode #{x.class}: #{x.inspect}"
      end
    end

### Private Instance Methods

abbrev(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 287
    def abbrev(s)
      t = s[0,10]
      p = t['`']
      t = t[0,p] if p
      t = t + '...' if t.length < s.length
      '`' + t + '`'
    end

arrenc(a) click to toggle source

    # File lib/rack/utils/okjson.rb, line 430
    def arrenc(a)
      '[' + a.map{|x| valenc(x)}.join(',') + ']'
    end

arrparse(ts) click to toggle source

Parses an “array” in the sense of RFC 4627. Returns the parsed value and any trailing tokens.

    # File lib/rack/utils/okjson.rb, line 171
    def arrparse(ts)
      ts = eat('[', ts)
      arr = []

      if ts[0][0] == ']'
        return arr, ts[1..-1]
      end

      v, ts = valparse(ts)
      arr << v

      if ts[0][0] == ']'
        return arr, ts[1..-1]
      end

      loop do
        ts = eat(',', ts)

        v, ts = valparse(ts)
        arr << v

        if ts[0][0] == ']'
          return arr, ts[1..-1]
        end
      end
    end

eat(typ, ts) click to toggle source

    # File lib/rack/utils/okjson.rb, line 199
    def eat(typ, ts)
      if ts[0][0] != typ
        raise Error, "expected #{typ} (got #{ts[0].inspect})"
      end
      ts[1..-1]
    end

falsetok(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 259
    def falsetok(s); s[0,5] == 'false' ? [:val, 'false', false] : [] end

hexdec4(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 394
    def hexdec4(s)
      if s.length != 4
        raise Error, 'short'
      end
      (nibble(s[0])<<12) | (nibble(s[1])<<8) | (nibble(s[2])<<4) | nibble(s[3])
    end

keyenc(k) click to toggle source

    # File lib/rack/utils/okjson.rb, line 435
    def keyenc(k)
      case k
      when String then strenc(k)
      else
        raise Error, "Hash key is not a string: #{k.inspect}"
      end
    end

lex(s) click to toggle source

Scans s and returns a list of json tokens, excluding white space (as defined in RFC 4627).

    # File lib/rack/utils/okjson.rb, line 209
    def lex(s)
      ts = []
      while s.length > 0
        typ, lexeme, val = tok(s)
        if typ == nil
          raise Error, "invalid character at #{s[0,10].inspect}"
        end
        if typ != :space
          ts << [typ, lexeme, val]
        end
        s = s[lexeme.length..-1]
      end
      ts
    end

nibble(c) click to toggle source

    # File lib/rack/utils/okjson.rb, line 415
    def nibble(c)
      if ?0 <= c && c <= ?9 then c.ord - ?0.ord
      elsif ?a <= c && c <= ?z then c.ord - ?a.ord + 10
      elsif ?A <= c && c <= ?Z then c.ord - ?A.ord + 10
      else
        raise Error, "invalid hex code #{c}"
      end
    end

nulltok(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 257
    def nulltok(s);  s[0,4] == 'null'  ? [:val, 'null',  nil]   : [] end

numenc(x) click to toggle source

    # File lib/rack/utils/okjson.rb, line 487
    def numenc(x)
      if ((x.nan? || x.infinite?) rescue false)
        raise Error, "Numeric cannot be represented: #{x}"
      end
      "#{x}"
    end

numtok(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 262
    def numtok(s)
      m = /-?([1-9][0-9]+|[0-9])([.][0-9]+)?([eE][+-]?[0-9]+)?/.match(s)
      if m && m.begin(0) == 0
        if !m[2] && !m[3]
          [:val, m[0], Integer(m[0])]
        elsif m[2]
          [:val, m[0], Float(m[0])]
        else
          [:val, m[0], Integer(m[1])*(10**m[3][1..-1].to_i(10))]
        end
      else
        []
      end
    end

objenc(x) click to toggle source

    # File lib/rack/utils/okjson.rb, line 425
    def objenc(x)
      '{' + x.map{|k,v| keyenc(k) + ':' + valenc(v)}.join(',') + '}'
    end

objparse(ts) click to toggle source

Parses an “object” in the sense of RFC 4627. Returns the parsed value and any trailing tokens.

    # File lib/rack/utils/okjson.rb, line 128
    def objparse(ts)
      ts = eat('{', ts)
      obj = {}

      if ts[0][0] == '}'
        return obj, ts[1..-1]
      end

      k, v, ts = pairparse(ts)
      obj[k] = v

      if ts[0][0] == '}'
        return obj, ts[1..-1]
      end

      loop do
        ts = eat(',', ts)

        k, v, ts = pairparse(ts)
        obj[k] = v

        if ts[0][0] == '}'
          return obj, ts[1..-1]
        end
      end
    end

pairparse(ts) click to toggle source

Parses a “member” in the sense of RFC 4627. Returns the parsed values and any trailing tokens.

    # File lib/rack/utils/okjson.rb, line 158
    def pairparse(ts)
      (typ, _, k), ts = ts[0], ts[1..-1]
      if typ != :str
        raise Error, "unexpected #{k.inspect}"
      end
      ts = eat(':', ts)
      v, ts = valparse(ts)
      [k, v, ts]
    end

rubydoesenc?() click to toggle source

    # File lib/rack/utils/okjson.rb, line 565
    def rubydoesenc?
      ::String.method_defined?(:force_encoding)
    end

strenc(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 444
    def strenc(s)
      t = StringIO.new
      t.putc(?")
      r = 0

      while r < s.length
        case s[r]
        when ?"  then t.print('\"')
        when ?\\ then t.print('\\')
        when ?\b then t.print('\b')
        when ?\f then t.print('\f')
        when ?\n then t.print('\n')
        when ?\r then t.print('\r')
        when ?\t then t.print('\t')
        else
          c = s[r]
          # In ruby >= 1.9, s[r] is a codepoint, not a byte.
          if rubydoesenc?
            begin
              # c.ord will raise an error if c is invalid UTF-8
              if c.ord < Spc.ord
                c = "\\u%04x" % [c.ord]
              end
              t.write(c)
            rescue
              t.write(Ustrerr)
            end
          elsif c < Spc
            t.write("\\u%04x" % c)
          elsif Spc <= c && c <= ?~
            t.putc(c)
          else
            n = ucharcopy(t, s, r) # ensure valid UTF-8 output
            r += n - 1 # r is incremented below
          end
        end
        r += 1
      end
      t.putc(?")
      t.string
    end

strtok(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 278
    def strtok(s)
      m = /"([^"\]|\["\/\bfnrt]|\u[0-9a-fA-F]{4})*"/.match(s)
      if ! m
        raise Error, "invalid string literal at #{abbrev(s)}"
      end
      [:str, m[0], unquote(m[0])]
    end

subst(u1, u2) click to toggle source

    # File lib/rack/utils/okjson.rb, line 402
    def subst(u1, u2)
      if Usurr1 <= u1 && u1 < Usurr2 && Usurr2 <= u2 && u2 < Usurr3
        return ((u1-Usurr1)<<10) | (u2-Usurr2) + Usurrself
      end
      return Ucharerr
    end

surrogate?(u) click to toggle source

    # File lib/rack/utils/okjson.rb, line 410
    def surrogate?(u)
      Usurr1 <= u && u < Usurr3
    end

textparse(ts) click to toggle source

Parses a “json text” in the sense of RFC 4627. Returns the parsed value and any trailing tokens. Note: this is almost the same as valparse, except that it does not accept atomic values.

    # File lib/rack/utils/okjson.rb, line 93
    def textparse(ts)
      if ts.length <= 0
        raise Error, 'empty'
      end

      typ, _, val = ts[0]
      case typ
      when '{' then objparse(ts)
      when '[' then arrparse(ts)
      else
        raise Error, "unexpected #{val.inspect}"
      end
    end

tok(s) click to toggle source

Scans the first token in s and returns a 3-element list, or nil if s does not begin with a valid token.

The first list element is one of '{', '}', ':', ',', '[', ']', :val, :str, and :space.

The second element is the lexeme.

The third element is the value of the token for :val and :str, otherwise it is the lexeme.

    # File lib/rack/utils/okjson.rb, line 238
    def tok(s)
      case s[0]
      when ?{ then ['{', s[0,1], s[0,1]]
      when ?} then ['}', s[0,1], s[0,1]]
      when ?: then [':', s[0,1], s[0,1]]
      when ?, then [',', s[0,1], s[0,1]]
      when ?[ then ['[', s[0,1], s[0,1]]
      when ?] then [']', s[0,1], s[0,1]]
      when ?n then nulltok(s)
      when ?t then truetok(s)
      when ?f then falsetok(s)
      when ?" then strtok(s)
      when Spc, ?\t, ?\n, ?\r then [:space, s[0,1], s[0,1]]
      else
        numtok(s)
      end
    end

truetok(s) click to toggle source

    # File lib/rack/utils/okjson.rb, line 258
    def truetok(s);  s[0,4] == 'true'  ? [:val, 'true',  true]  : [] end

ucharcopy(t, s, i) click to toggle source

Copies the valid UTF-8 bytes of a single character from string s at position i to I/O object t, and returns the number of bytes copied. If no valid UTF-8 char exists at position i, ucharcopy writes Ustrerr and returns 1.

    # File lib/rack/utils/okjson.rb, line 500
    def ucharcopy(t, s, i)
      n = s.length - i
      raise Utf8Error if n < 1

      c0 = s[i].ord

      # 1-byte, 7-bit sequence?
      if c0 < Utagx
        t.putc(c0)
        return 1
      end

      raise Utf8Error if c0 < Utag2 # unexpected continuation byte?

      raise Utf8Error if n < 2 # need continuation byte
      c1 = s[i+1].ord
      raise Utf8Error if c1 < Utagx || Utag2 <= c1

      # 2-byte, 11-bit sequence?
      if c0 < Utag3
        raise Utf8Error if ((c0&Umask2)<<6 | (c1&Umaskx)) <= Uchar1max
        t.putc(c0)
        t.putc(c1)
        return 2
      end

      # need second continuation byte
      raise Utf8Error if n < 3

      c2 = s[i+2].ord
      raise Utf8Error if c2 < Utagx || Utag2 <= c2

      # 3-byte, 16-bit sequence?
      if c0 < Utag4
        u = (c0&Umask3)<<12 | (c1&Umaskx)<<6 | (c2&Umaskx)
        raise Utf8Error if u <= Uchar2max
        t.putc(c0)
        t.putc(c1)
        t.putc(c2)
        return 3
      end

      # need third continuation byte
      raise Utf8Error if n < 4
      c3 = s[i+3].ord
      raise Utf8Error if c3 < Utagx || Utag2 <= c3

      # 4-byte, 21-bit sequence?
      if c0 < Utag5
        u = (c0&Umask4)<<18 | (c1&Umaskx)<<12 | (c2&Umaskx)<<6 | (c3&Umaskx)
        raise Utf8Error if u <= Uchar3max
        t.putc(c0)
        t.putc(c1)
        t.putc(c2)
        t.putc(c3)
        return 4
      end

      raise Utf8Error
    rescue Utf8Error
      t.write(Ustrerr)
      return 1
    end

ucharenc(a, i, u) click to toggle source

Encodes unicode character u as UTF-8 bytes in string a at position i. Returns the number of bytes written.

    # File lib/rack/utils/okjson.rb, line 371
    def ucharenc(a, i, u)
      if u <= Uchar1max
        a[i] = (u & 0xff).chr
        1
      elsif u <= Uchar2max
        a[i+0] = (Utag2 | ((u>>6)&0xff)).chr
        a[i+1] = (Utagx | (u&Umaskx)).chr
        2
      elsif u <= Uchar3max
        a[i+0] = (Utag3 | ((u>>12)&0xff)).chr
        a[i+1] = (Utagx | ((u>>6)&Umaskx)).chr
        a[i+2] = (Utagx | (u&Umaskx)).chr
        3
      else
        a[i+0] = (Utag4 | ((u>>18)&0xff)).chr
        a[i+1] = (Utagx | ((u>>12)&Umaskx)).chr
        a[i+2] = (Utagx | ((u>>6)&Umaskx)).chr
        a[i+3] = (Utagx | (u&Umaskx)).chr
        4
      end
    end

unquote(q) click to toggle source

Converts a quoted json string literal q into a UTF-8-encoded string. The rules are different than for Ruby, so we cannot use eval. Unquote will raise an error if q contains control characters.

    # File lib/rack/utils/okjson.rb, line 299
    def unquote(q)
      q = q[1...-1]
      a = q.dup # allocate a big enough string
      # In ruby >= 1.9, a[w] is a codepoint, not a byte.
      if rubydoesenc?
        a.force_encoding('UTF-8')
      end
      r, w = 0, 0
      while r < q.length
        c = q[r]
        if c == ?\         r += 1
          if r >= q.length
            raise Error, "string literal ends with a \"\\\": \"#{q}\""
          end

          case q[r]
          when ?",?\\,?/,?'
            a[w] = q[r]
            r += 1
            w += 1
          when ?b,?f,?n,?r,?t
            a[w] = Unesc[q[r]]
            r += 1
            w += 1
          when ?u
            r += 1
            uchar = begin
              hexdec4(q[r,4])
            rescue RuntimeError => e
              raise Error, "invalid escape sequence \\u#{q[r,4]}: #{e}"
            end
            r += 4
            if surrogate? uchar
              if q.length >= r+6
                uchar1 = hexdec4(q[r+2,4])
                uchar = subst(uchar, uchar1)
                if uchar != Ucharerr
                  # A valid pair; consume.
                  r += 6
                end
              end
            end
            if rubydoesenc?
              a[w] = '' << uchar
              w += 1
            else
              w += ucharenc(a, w, uchar)
            end
          else
            raise Error, "invalid escape char #{q[r]} in \"#{q}\""
          end
        elsif c == ?" || c < Spc
          raise Error, "invalid character in string literal \"#{q}\""
        else
          # Copy anything else byte-for-byte.
          # Valid UTF-8 will remain valid UTF-8.
          # Invalid UTF-8 will remain invalid UTF-8.
          # In ruby >= 1.9, c is a codepoint, not a byte,
          # in which case this is still what we want.
          a[w] = c
          r += 1
          w += 1
        end
      end
      a[0,w]
    end

valparse(ts) click to toggle source

Parses a “value” in the sense of RFC 4627. Returns the parsed value and any trailing tokens.

    # File lib/rack/utils/okjson.rb, line 110
    def valparse(ts)
      if ts.length <= 0
        raise Error, 'empty'
      end

      typ, _, val = ts[0]
      case typ
      when '{' then objparse(ts)
      when '[' then arrparse(ts)
      when :val,:str then [val, ts[1..-1]]
      else
        raise Error, "unexpected #{val.inspect}"
      end
    end