- case '\\': o[len++] = '\\';s++; break;
- case '"': o[len++] = '"';s++; break;
- case 'b': o[len++] = '\b';s++; break;
- case 'f': o[len++] = '\f';s++; break;
- case 'n': o[len++] = '\n';s++; break;
- case 'r': o[len++] = '\r';s++; break;
- case 't': o[len++] = '\t';s++; break;
+ case '\\': if(o) o[len] = '\\';s++;len++; break;
+ case '"': if(o) o[len] = '"';s++;len++; break;
+ case 'b': if(o) o[len] = '\b';s++;len++; break;
+ case 'f': if(o) o[len] = '\f';s++;len++; break;
+ case 'n': if(o) o[len] = '\n';s++;len++; break;
+ case 'r': if(o) o[len] = '\r';s++;len++; break;
+ case 't': if(o) o[len] = '\t';s++;len++; break;