Class: BcsReader
Class used for reading BCS data chunk by chunk. Meant to be used by some wrapper, which will make sure that data is valid and is matching the desired format.
Examples
// data for this example is:
// { a: u8, b: u32, c: bool, d: u64 }
let reader = new BcsReader("647f1a060001ffffe7890423c78a050102030405");
let field1 = reader.read8();
let field2 = reader.read32();
let field3 = reader.read8() === '1'; // bool
let field4 = reader.read64();
// ....
Reading vectors is another deal in bcs. To read a vector, you first need to read
its length using {@link readULEB}. Here's an example:
// data encoded: { field: [1, 2, 3, 4, 5] }
let reader = new BcsReader("050102030405");
let vec_length = reader.readULEB();
let elements = [];
for (let i = 0; i < vec_length; i++) {
elements.push(reader.read8());
}
console.log(elements); // [1,2,3,4,5]
Param
HEX-encoded data (serialized BCS)
Constructors
Constructor
new BcsReader(data): BcsReader;
Parameters
| Parameter | Type | Description |
|---|---|---|
data | Uint8Array | Data to use as a buffer. |
Returns
BcsReader
Methods
shift()
shift(bytes): BcsReader;
Shift current cursor position by bytes.
Parameters
| Parameter | Type | Description |
|---|---|---|
bytes | number | Number of bytes to |
Returns
BcsReader
Self for possible chaining.
read8()
read8(): number;
Read U8 value from the buffer and shift cursor by 1.
Returns
number
read16()
read16(): number;
Read U16 value from the buffer and shift cursor by 2.
Returns
number
read32()
read32(): number;
Read U32 value from the buffer and shift cursor by 4.
Returns
number
read64()
read64(): string;
Read U64 value from the buffer and shift cursor by 8.
Returns
string
read128()
read128(): string;
Read U128 value from the buffer and shift cursor by 16.
Returns
string
read256()
read256(): string;
Read U128 value from the buffer and shift cursor by 32.
Returns
string
readBytes()
readBytes(num): Uint8Array;
Read num number of bytes from the buffer and shift cursor by num.
Parameters
| Parameter | Type | Description |
|---|---|---|
num | number | Number of bytes to read. |
Returns
Uint8Array
readULEB()
readULEB(): number;
Read ULEB value - an integer of varying size. Used for enum indexes and vector lengths.
Returns
number
The ULEB value.
readVec()
readVec(cb): any[];
Read a BCS vector: read a length and then apply function cb X times
where X is the length of the vector, defined as ULEB in BCS bytes.
Parameters
| Parameter | Type | Description |
|---|---|---|
cb | (reader, i, length) => any | Callback to process elements of vector. |
Returns
any[]
Array of the resulting values, returned by callback.