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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​

data​

Uint8Array

Data to use as a buffer.

Returns​

BcsReader

Methods​

shift()​

shift(bytes): BcsReader

Shift current cursor position by bytes.

Parameters​

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​

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​

cb​

(reader, i, length) => any

Callback to process elements of vector.

Returns​

any[]

Array of the resulting values, returned by callback.