bert.js 7.0 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)), s = "";
  12. for (var i=0; i < buf.length; i++) { buf[i] = ori.charCodeAt(i); s+=","+buf[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. TUPLE = itoa(104);
  24. LTUPLE = itoa(105);
  25. NIL = itoa(106);
  26. ZERO = itoa(0);
  27. function itoa(x) { return String.fromCharCode(x); }
  28. function ltoa(a) { for (var i = 0,s=""; i < a.length; i++) s += itoa(a[i]); return s; };
  29. function itol(Int, Length) {
  30. var isNegative, OriginalInt, i, Rem, s = "";
  31. isNegative = (Int < 0);
  32. if (isNegative) { Int = Int * (0 - 1); }
  33. OriginalInt = Int;
  34. for (i = 0; i < Length; i++) {
  35. Rem = Int % 256;
  36. if (isNegative) { Rem = 255 - Rem; }
  37. s = String.fromCharCode(Rem) + s;
  38. Int = Math.floor(Int / 256);
  39. }
  40. if (Int > 0) { throw ("BERT: Range: " + OriginalInt); }
  41. return s; };
  42. function ltoi(S, Length) {
  43. var isNegative, i, n, Num = 0;
  44. isNegative = (S.charCodeAt(0) > 128);
  45. for (i = 0; i < Length; i++) {
  46. n = S.charCodeAt(i);
  47. if (isNegative) { n = 255 - n; }
  48. if (Num === 0) { Num = n; }
  49. else { Num = Num * 256 + n; }
  50. }
  51. if (isNegative) { Num = Num * (0 - 1); }
  52. return Num; };
  53. function encode(o) { return BERT + en_inner(o); };
  54. function en_inner(Obj) { if(Obj === undefined) return NIL; var func = 'en_' + typeof(Obj); return eval(func)(Obj); };
  55. function en_string(Obj) { return STR + itol(Obj.length, 2) + Obj; };
  56. function en_boolean(Obj) { if (Obj) return en_inner(atom("true")); else return en_inner(atom("false")); };
  57. function en_number(Obj) { var s, isi = (Obj % 1 === 0); if (!isi) { return en_float(Obj); }
  58. if (isi && Obj >= 0 && Obj < 256) { return SINT + itol(Obj, 1); }
  59. return INT + itol(Obj, 4); };
  60. function en_float(Obj) { var s = Obj.toExponential(); while (s.length < 31) { s += ZERO; } return FLOAT + s; };
  61. function en_object(Obj) {
  62. if (Obj.type === "Atom") return en_atom(Obj);
  63. if (Obj.type === "Binary") return en_bin(Obj);
  64. if (Obj.type === "Tuple") return en_tuple(Obj);
  65. if (Obj.constructor.toString().indexOf("Array") !== -1) return en_array(Obj);
  66. return en_associative_array(Obj); };
  67. function en_atom(Obj) { return ATOM + itol(Obj.value.length, 2) + Obj.value; };
  68. function en_bin(Obj) { return BINARY + itol(Obj.value.length, 4) + Obj.value; };
  69. function en_tuple(Obj) {
  70. var i, s = "";
  71. if (Obj.value.length < 256) { s += TUPLE + itol(Obj.value.length, 1); }
  72. else { s += LTUPLE + itol(Obj.value.length, 4); }
  73. for (i = 0; i < Obj.value.length; i++) { s += en_inner(Obj.value[i]); }
  74. return s; };
  75. function en_array(Obj) {
  76. var i, s = LIST + itol(Obj.length, 4);
  77. for (i = 0; i < Obj.length; i++) { s += en_inner(Obj[i]); }
  78. s += NIL;
  79. return s; };
  80. function en_associative_array(Obj) {
  81. var key, Arr = [];
  82. for (key in Obj) { if (Obj.hasOwnProperty(key)) { Arr.push(tuple(atom(key), Obj[key])); } }
  83. return en_array(Arr); };
  84. function decode(S) {
  85. if (S[0] !== BERT) { throw ("Not a valid BERT."); }
  86. var Obj = de_inner(S.substring(1));
  87. if (Obj.rest !== "") { throw ("Invalid BERT."); }
  88. return Obj.value; };
  89. function de_inner(S) {
  90. var Type = S[0];
  91. S = S.substring(1);
  92. switch (Type) {
  93. case SATOM: de_atom(S, 1);
  94. case ATOM: return de_atom(S, 2);
  95. case BINARY: return de_bin(S);
  96. case SINT: return de_integer(S, 1);
  97. case INT: return de_integer(S, 4);
  98. case FLOAT: return de_float(S);
  99. case STR: return de_string(S);
  100. case LIST: return de_list(S);
  101. case TUPLE: return de_tuple(S, 1);
  102. case NIL: return de_nil(S);
  103. default: throw ("BERT: " + S.charCodeAt(0)); } };
  104. function de_atom(S, Count) {
  105. var Size, Value;
  106. Size = ltoi(S, Count);
  107. S = S.substring(Count);
  108. Value = S.substring(0, Size);
  109. if (Value === "true") { Value = true; }
  110. else if (Value === "false") { Value = false; }
  111. return { value: atom(Value), rest: S.substring(Size) }; };
  112. function de_bin(S) {
  113. var Size = ltoi(S, 4);
  114. S = S.substring(4);
  115. return { value: bin(S.substring(0, Size)), rest: S.substring(Size) }; };
  116. function de_integer(S, Count) {
  117. var Value = ltoi(S, Count);
  118. S = S.substring(Count);
  119. return { value: Value, rest: S }; };
  120. function de_float(S) {
  121. var Size = 31;
  122. return { value: parseFloat(S.substring(0, Size)), rest: S.substring(Size) }; };
  123. function de_string(S) {
  124. var Size = ltoi(S, 2);
  125. S = S.substring(2);
  126. return { value: S.substring(0, Size), rest: S.substring(Size) }; };
  127. function de_list(S) {
  128. var Size, i, El, LastChar, Arr = [];
  129. Size = ltoi(S, 4);
  130. S = S.substring(4);
  131. for (i = 0; i < Size; i++) { El = de_inner(S); Arr.push(El.value); S = El.rest; }
  132. LastChar = S[0];
  133. if (LastChar !== NIL) { throw ("BERT: Wrong NIL."); }
  134. S = S.substring(1);
  135. return { value: Arr, rest: S }; };
  136. function de_tuple(S, Count) {
  137. var Size, i, El, Arr = [];
  138. Size = ltoi(S, Count);
  139. S = S.substring(Count);
  140. for (i = 0; i < Size; i++) { El = de_inner(S); Arr.push(El.value); S = El.rest; }
  141. return { value: tuple(Arr), rest: S }; };
  142. function de_nil(S) { return { value: [], rest: S }; };
  143. function utf8toByteArray(str) {
  144. var byteArray = [];
  145. if (str !== undefined && str !== null)
  146. for (var i = 0; i < str.length; i++)
  147. if (str.charCodeAt(i) <= 0x7F)
  148. byteArray.push(str.charCodeAt(i));
  149. else {
  150. var h = encodeURIComponent(str.charAt(i)).substr(1).split('%');
  151. for (var j = 0; j < h.length; j++)
  152. byteArray.push(parseInt(h[j], 16));
  153. }
  154. return byteArray;
  155. }
  156. function utf8decode(utftext) {
  157. var string = "";
  158. var i = 0;
  159. var c = c1 = c2 = 0;
  160. while ( i < utftext.length ) {
  161. c = utftext.charCodeAt(i);
  162. if (c < 128) {string += String.fromCharCode(c); i++;}
  163. else if((c > 191) && (c < 224)) {
  164. c2 = utftext.charCodeAt(i+1);
  165. string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
  166. i += 2;
  167. }
  168. else {
  169. c2 = utftext.charCodeAt(i+1);
  170. c3 = utftext.charCodeAt(i+2);
  171. string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
  172. i += 3;
  173. }
  174. }
  175. return string;
  176. }