bert.js 6.4 KB

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  1. // Micro BERT encoder/decoder
  2. // Copyright (c) Maxim Sokhatsky (@5HT)
  3. function atom(o) { return { type: "Atom", value: o, toString: function() { return this.value; } }; };
  4. function bin(o) { return { type: "Binary", value: o, toString: function() { return "<<\'"+this.value+"'>>"; } }; };
  5. function tuple() {
  6. return { type: "Tuple", value: arguments, toString: function() { var s = "";
  7. for (var i=0;i<this.value.length;i++) { if (s!=="") s+=","; s+=this.value[i]; }
  8. return "{" + s + "}"; } }; };
  9. function dec(S) { return decode(ltoa(new Uint8Array(S))); };
  10. function enc(s) {
  11. var ori = encode(s), buf = new Uint8Array(new ArrayBuffer(ori.length));
  12. for (var i=0; i < buf.length; i++) { buf[i] = ori.charCodeAt(i); }
  13. return new Blob([buf.buffer]); };
  14. BERT = itoa(131);
  15. SATOM = itoa(115);
  16. ATOM = itoa(100);
  17. BINARY = itoa(109);
  18. SINT = itoa(97);
  19. INT = itoa(98);
  20. FLOAT = itoa(99);
  21. STR = itoa(107);
  22. LIST = itoa(108);
  23. SBIG = itoa(110);
  24. LBIG = itoa(111);
  25. TUPLE = itoa(104);
  26. LTUPLE = itoa(105);
  27. NIL = itoa(106);
  28. ZERO = itoa(0);
  29. function itoa(x) { return String.fromCharCode(x); }
  30. function ltoa(a) { for (var i = 0,s=""; i < a.length; i++) s += itoa(a[i]); return s; };
  31. function itol(Int, Length) {
  32. var isNegative, OriginalInt, i, Rem, s = "";
  33. isNegative = (Int < 0);
  34. if (isNegative) { Int = Int * (0 - 1); }
  35. OriginalInt = Int;
  36. for (i = 0; i < Length; i++) {
  37. Rem = Int % 256;
  38. if (isNegative) { Rem = 255 - Rem; }
  39. s = String.fromCharCode(Rem) + s;
  40. Int = Math.floor(Int / 256);
  41. }
  42. if (Int > 0) { throw ("BERT: Range: " + OriginalInt); }
  43. return s; };
  44. function ltoi(S, Length) {
  45. var isNegative, i, n, Num = 0;
  46. isNegative = (S.charCodeAt(0) > 128);
  47. for (i = 0; i < Length; i++) {
  48. n = S.charCodeAt(i);
  49. if (isNegative) { n = 255 - n; }
  50. if (Num === 0) { Num = n; }
  51. else { Num = Num * 256 + n; }
  52. }
  53. if (isNegative) { Num = Num * (0 - 1); }
  54. return Num; };
  55. function ltobi(S, Count) {
  56. var isNegative, i, n, Num = 0;
  57. isNegative = (S.charCodeAt(0) === 1);
  58. S = S.substring(1);
  59. for (i = Count - 1; i >= 0; i--) {
  60. n = S.charCodeAt(i);
  61. if (Num === 0) { Num = n; } else { Num = Num * 256 + n; } }
  62. if (isNegative) { return Num * -1; }
  63. return Num; };
  64. function encode(o) { return BERT + en_inner(o); };
  65. function en_inner(Obj) { if(Obj === undefined) return NIL; var func = 'en_' + typeof(Obj); return eval(func)(Obj); };
  66. function en_string(Obj) { return STR + itol(Obj.length, 2) + Obj; };
  67. function en_boolean(Obj) { if (Obj) return en_inner(atom("true")); else return en_inner(atom("false")); };
  68. function en_number(Obj) { var s, isi = (Obj % 1 === 0); if (!isi) { return en_float(Obj); }
  69. if (isi && Obj >= 0 && Obj < 256) { return SINT + itol(Obj, 1); }
  70. return INT + itol(Obj, 4); };
  71. function en_float(Obj) { var s = Obj.toExponential(); while (s.length < 31) { s += ZERO; } return FLOAT + s; };
  72. function en_object(Obj) {
  73. if (Obj.type === "Atom") return en_atom(Obj);
  74. if (Obj.type === "Binary") return en_bin(Obj);
  75. if (Obj.type === "Tuple") return en_tuple(Obj);
  76. if (Obj.constructor.toString().indexOf("Array") !== -1) return en_array(Obj);
  77. return en_associative_array(Obj); };
  78. function en_atom(Obj) { return ATOM + itol(Obj.value.length, 2) + Obj.value; };
  79. function en_bin(Obj) { return BINARY + itol(Obj.value.length, 4) + Obj.value; };
  80. function en_tuple(Obj) {
  81. var i, s = "";
  82. if (Obj.value.length < 256) { s += TUPLE + itol(Obj.value.length, 1); }
  83. else { s += LTUPLE + itol(Obj.value.length, 4); }
  84. for (i = 0; i < Obj.value.length; i++) { s += en_inner(Obj.value[i]); }
  85. return s; };
  86. function en_array(Obj) {
  87. var i, s = LIST + itol(Obj.length, 4);
  88. for (i = 0; i < Obj.length; i++) { s += en_inner(Obj[i]); }
  89. s += NIL;
  90. return s; };
  91. function en_associative_array(Obj) {
  92. var key, Arr = [];
  93. for (key in Obj) { if (Obj.hasOwnProperty(key)) { Arr.push(tuple(atom(key), Obj[key])); } }
  94. return en_array(Arr); };
  95. function decode(S) {
  96. if (S[0] !== BERT) { throw ("Not a valid BERT."); }
  97. var Obj = de_inner(S.substring(1));
  98. if (Obj.rest !== "") { throw ("Invalid BERT."); }
  99. return Obj.value; };
  100. function de_inner(S) {
  101. var Type = S[0];
  102. S = S.substring(1);
  103. switch (Type) {
  104. case SATOM: de_atom(S, 1);
  105. case ATOM: return de_atom(S, 2);
  106. case BINARY: return de_bin(S);
  107. case SINT: return de_integer(S, 1);
  108. case INT: return de_integer(S, 4);
  109. case FLOAT: return de_float(S);
  110. case SBIG: return de_big(S,1);
  111. case LBIG: return de_big(S,4);
  112. case STR: return de_string(S);
  113. case LIST: return de_list(S);
  114. case TUPLE: return de_tuple(S, 1);
  115. case NIL: return de_nil(S);
  116. default: throw ("BERT: " + S.charCodeAt(0)); } };
  117. function de_atom(S, Count) {
  118. var Size, Value;
  119. Size = ltoi(S, Count);
  120. S = S.substring(Count);
  121. Value = S.substring(0, Size);
  122. if (Value === "true") { Value = true; }
  123. else if (Value === "false") { Value = false; }
  124. return { value: atom(Value), rest: S.substring(Size) }; };
  125. function de_bin(S) {
  126. var Size = ltoi(S, 4);
  127. S = S.substring(4);
  128. return { value: bin(S.substring(0, Size)), rest: S.substring(Size) }; };
  129. function de_big(S, Count) {
  130. var Size, Value;
  131. Size = ltoi(S, Count);
  132. S = S.substring(Count);
  133. Value = ltobi(S, Size);
  134. return { value : Value, rest: S.substring(Size + 1) }; };
  135. function de_integer(S, Count) {
  136. var Value = ltoi(S, Count);
  137. S = S.substring(Count);
  138. return { value: Value, rest: S }; };
  139. function de_float(S) {
  140. var Size = 31;
  141. return { value: parseFloat(S.substring(0, Size)), rest: S.substring(Size) }; };
  142. function de_string(S) {
  143. var Size = ltoi(S, 2);
  144. S = S.substring(2);
  145. return { value: S.substring(0, Size), rest: S.substring(Size) }; };
  146. function de_list(S) {
  147. var Size, i, El, LastChar, Arr = [];
  148. Size = ltoi(S, 4);
  149. S = S.substring(4);
  150. for (i = 0; i < Size; i++) { El = de_inner(S); Arr.push(El.value); S = El.rest; }
  151. LastChar = S[0];
  152. if (LastChar !== NIL) { throw ("BERT: Wrong NIL."); }
  153. S = S.substring(1);
  154. return { value: Arr, rest: S }; };
  155. function de_tuple(S, Count) {
  156. var Size, i, El, Arr = [];
  157. Size = ltoi(S, Count);
  158. S = S.substring(Count);
  159. for (i = 0; i < Size; i++) { El = de_inner(S); Arr.push(El.value); S = El.rest; }
  160. return { value: tuple(Arr), rest: S }; };
  161. function de_nil(S) { return { value: [], rest: S }; };