@brtnetwork/brt-binary-codec
Version:
BRT Ledger binary codec
185 lines • 6.03 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.BinaryParser = void 0;
var assert = require("assert");
var enums_1 = require("../enums");
var buffer_1 = require("buffer/");
/**
* BinaryParser is used to compute fields and values from a HexString
*/
var BinaryParser = /** @class */ (function () {
/**
* Initialize bytes to a hex string
*
* @param hexBytes a hex string
*/
function BinaryParser(hexBytes) {
this.bytes = buffer_1.Buffer.from(hexBytes, "hex");
}
/**
* Peek the first byte of the BinaryParser
*
* @returns The first byte of the BinaryParser
*/
BinaryParser.prototype.peek = function () {
assert(this.bytes.byteLength !== 0);
return this.bytes[0];
};
/**
* Consume the first n bytes of the BinaryParser
*
* @param n the number of bytes to skip
*/
BinaryParser.prototype.skip = function (n) {
assert(n <= this.bytes.byteLength);
this.bytes = this.bytes.slice(n);
};
/**
* read the first n bytes from the BinaryParser
*
* @param n The number of bytes to read
* @return The bytes
*/
BinaryParser.prototype.read = function (n) {
assert(n <= this.bytes.byteLength);
var slice = this.bytes.slice(0, n);
this.skip(n);
return slice;
};
/**
* Read an integer of given size
*
* @param n The number of bytes to read
* @return The number represented by those bytes
*/
BinaryParser.prototype.readUIntN = function (n) {
assert(0 < n && n <= 4, "invalid n");
return this.read(n).reduce(function (a, b) { return (a << 8) | b; }) >>> 0;
};
BinaryParser.prototype.readUInt8 = function () {
return this.readUIntN(1);
};
BinaryParser.prototype.readUInt16 = function () {
return this.readUIntN(2);
};
BinaryParser.prototype.readUInt32 = function () {
return this.readUIntN(4);
};
BinaryParser.prototype.size = function () {
return this.bytes.byteLength;
};
BinaryParser.prototype.end = function (customEnd) {
var length = this.bytes.byteLength;
return length === 0 || (customEnd !== undefined && length <= customEnd);
};
/**
* Reads variable length encoded bytes
*
* @return The variable length bytes
*/
BinaryParser.prototype.readVariableLength = function () {
return this.read(this.readVariableLengthLength());
};
/**
* Reads the length of the variable length encoded bytes
*
* @return The length of the variable length encoded bytes
*/
BinaryParser.prototype.readVariableLengthLength = function () {
var b1 = this.readUInt8();
if (b1 <= 192) {
return b1;
}
else if (b1 <= 240) {
var b2 = this.readUInt8();
return 193 + (b1 - 193) * 256 + b2;
}
else if (b1 <= 254) {
var b2 = this.readUInt8();
var b3 = this.readUInt8();
return 12481 + (b1 - 241) * 65536 + b2 * 256 + b3;
}
throw new Error("Invalid variable length indicator");
};
/**
* Reads the field ordinal from the BinaryParser
*
* @return Field ordinal
*/
BinaryParser.prototype.readFieldOrdinal = function () {
var type = this.readUInt8();
var nth = type & 15;
type >>= 4;
if (type === 0) {
type = this.readUInt8();
if (type === 0 || type < 16) {
throw new Error("Cannot read FieldOrdinal, type_code out of range");
}
}
if (nth === 0) {
nth = this.readUInt8();
if (nth === 0 || nth < 16) {
throw new Error("Cannot read FieldOrdinal, field_code out of range");
}
}
return (type << 16) | nth;
};
/**
* Read the field from the BinaryParser
*
* @return The field represented by the bytes at the head of the BinaryParser
*/
BinaryParser.prototype.readField = function () {
return enums_1.Field.fromString(this.readFieldOrdinal().toString());
};
/**
* Read a given type from the BinaryParser
*
* @param type The type that you want to read from the BinaryParser
* @return The instance of that type read from the BinaryParser
*/
BinaryParser.prototype.readType = function (type) {
return type.fromParser(this);
};
/**
* Get the type associated with a given field
*
* @param field The field that you wan to get the type of
* @return The type associated with the given field
*/
BinaryParser.prototype.typeForField = function (field) {
return field.associatedType;
};
/**
* Read value of the type specified by field from the BinaryParser
*
* @param field The field that you want to get the associated value for
* @return The value associated with the given field
*/
BinaryParser.prototype.readFieldValue = function (field) {
var type = this.typeForField(field);
if (!type) {
throw new Error("unsupported: (" + field.name + ", " + field.type.name + ")");
}
var sizeHint = field.isVariableLengthEncoded
? this.readVariableLengthLength()
: undefined;
var value = type.fromParser(this, sizeHint);
if (value === undefined) {
throw new Error("fromParser for (" + field.name + ", " + field.type.name + ") -> undefined ");
}
return value;
};
/**
* Get the next field and value from the BinaryParser
*
* @return The field and value
*/
BinaryParser.prototype.readFieldAndValue = function () {
var field = this.readField();
return [field, this.readFieldValue(field)];
};
return BinaryParser;
}());
exports.BinaryParser = BinaryParser;
//# sourceMappingURL=binary-parser.js.map