ts-ebml-esm/lib/EBMLDecoder.cjs.js

ebml decoder and encoder

"use strict";const i=require("bigint-buffer"),r=require("./tools-Bzvjx2Tw.cjs"),c=require("matroska-schema"),{byEbmlID:_}=c;class f{constructor(){this._buffer=Buffer.alloc(0),this._tag_stack=[],this._state=1,this._cursor=0,this._total=0,this._schema=_,this._result=[]}decode(t){this.readChunk(t);const e=this._result;return this._result=[],e}readChunk(t){for(this._buffer=r.concat([this._buffer,Buffer.from(t)]);this._cursor<this._buffer.length&&!(this._state===1&&!this.readTag()||this._state===2&&!this.readSize()||this._state===3&&!this.readContent()););}getSchemaInfo(t){return this._schema[t]!=null?this._schema[t]:{name:"unknown",level:-1,type:"unknown",description:"unknown"}}readTag(){if(this._cursor>=this._buffer.length)return!1;const t=r.readVint(this._buffer,this._cursor);if(t==null)return!1;const s=this._buffer.subarray(this._cursor,this._cursor+t.length).reduce((u,h,l,o)=>u+h*Math.pow(16,2*(o.length-1-l)),0),a=this.getSchemaInfo(s),n={EBML_ID:s.toString(16),schema:a,type:a.type,name:a.name,level:a.level,tagStart:this._total,tagEnd:this._total+t.length,sizeStart:this._total+t.length,sizeEnd:null,dataStart:null,dataEnd:null,dataSize:null,data:null};return this._tag_stack.push(n),this._cursor+=t.length,this._total+=t.length,this._state=2,!0}readSize(){if(this._cursor>=this._buffer.length)return!1;const t=r.readVint(this._buffer,this._cursor);if(t==null)return!1;const e=this._tag_stack[this._tag_stack.length-1];return e==null?!1:(e.sizeEnd=e.sizeStart+t.length,e.dataStart=e.sizeEnd,e.dataSize=t.value,t.value===-1?(e.dataEnd=-1,e.type==="m"&&(e.unknownSize=!0)):e.dataEnd=e.sizeEnd+t.value,this._cursor+=t.length,this._total+=t.length,this._state=3,!0)}readContent(){const t=this._tag_stack[this._tag_stack.length-1];if(t==null)return!1;if(t.type==="m"){if(t.isEnd=!1,this._result.push(t),this._state=1,t.dataSize===0){const s=Object.assign({},t,{isEnd:!0});this._result.push(s),this._tag_stack.pop()}return!0}if(this._buffer.length<this._cursor+t.dataSize)return!1;const e=this._buffer.subarray(this._cursor,this._cursor+t.dataSize);switch(this._buffer=this._buffer.subarray(this._cursor+t.dataSize),t.data=e,t.type){case"u":{e.length>6?t.value=Number(i.toBigIntBE(e)):t.value=e.readUIntBE(0,e.length);break}case"i":{t.value=e.readIntBE(0,e.length);break}case"f":{t.dataSize===4?t.value=e.readFloatBE(0):t.dataSize===8?t.value=e.readDoubleBE(0):(console.warn(`cannot read ${t.dataSize} octets float. failback to 0`),t.value=0);break}case"s":{t.value=e.toString("ascii");break}case"8":{t.value=e.toString("utf8");break}case"b":{t.value=e;break}case"d":{t.value=r.convertEBMLDateToJSDate(Number(i.toBigIntBE(e)));break}}if(t.value===null)throw new Error("unknown tag type:"+t.type);for(this._result.push(t),this._total+=t.dataSize,this._state=1,this._cursor=0,this._tag_stack.pop();this._tag_stack.length>0;){const s=this._tag_stack[this._tag_stack.length-1];if(s==null)return!1;if(s.dataEnd<0)return this._tag_stack.pop(),!0;if(this._total<s.dataEnd)break;if(s.type!=="m")throw new Error("parent element is not master element");const a=Object.assign({},s,{isEnd:!0});this._result.push(a),this._tag_stack.pop()}return!0}}module.exports=f;