code: function parseExpression() {
  		if ( reader.eof() ) {
  			return 0;
  		}
  
  		let token;
  		let oPos = {};
  		oPos.start = reader.getPos();
  		if ( options.ExpressionStart.length > options.ExpressionUnescapeStart.length ) {
  			// 起始符较长者优先
  			token = parseExpr(options.ExpressionStart, options.ExpressionEnd, options.TypeEscapeExpression) || parseExpr(options.ExpressionUnescapeStart, options.ExpressionUnescapeEnd, options.TypeUnescapeExpression);
  		}else{
  			token = parseExpr(options.ExpressionUnescapeStart, options.ExpressionUnescapeEnd, options.TypeUnescapeExpression) || parseExpr(options.ExpressionStart, options.ExpressionEnd, options.TypeEscapeExpression);
  		}
  
  		if ( token ) {
  			oPos.end = reader.getPos();
  			token.pos = oPos;
  			tokens.push(token);
  			return 1;
  		}
  		return 0;
  	}
docs: 表达式 { } 或 {= }