ethers.js/lib.esm/utils/rlp-decode.js

//See: https://github.com/ethereum/wiki/wiki/RLP
import { hexlify } from "./data.js";
import { assert, assertArgument } from "./errors.js";
import { getBytes } from "./data.js";
function hexlifyByte(value) {
    let result = value.toString(16);
    while (result.length < 2) {
        result = "0" + result;
    }
    return "0x" + result;
}
function unarrayifyInteger(data, offset, length) {
    let result = 0;
    for (let i = 0; i < length; i++) {
        result = (result * 256) + data[offset + i];
    }
    return result;
}
function _decodeChildren(data, offset, childOffset, length) {
    const result = [];
    while (childOffset < offset + 1 + length) {
        const decoded = _decode(data, childOffset);
        result.push(decoded.result);
        childOffset += decoded.consumed;
        assert(childOffset <= offset + 1 + length, "child data too short", "BUFFER_OVERRUN", {
            buffer: data, length, offset
        });
    }
    return { consumed: (1 + length), result: result };
}
// returns { consumed: number, result: Object }
function _decode(data, offset) {
    assert(data.length !== 0, "data too short", "BUFFER_OVERRUN", {
        buffer: data, length: 0, offset: 1
    });
    const checkOffset = (offset) => {
        assert(offset <= data.length, "data short segment too short", "BUFFER_OVERRUN", {
            buffer: data, length: data.length, offset
        });
    };
    // Array with extra length prefix
    if (data[offset] >= 0xf8) {
        const lengthLength = data[offset] - 0xf7;
        checkOffset(offset + 1 + lengthLength);
        const length = unarrayifyInteger(data, offset + 1, lengthLength);
        checkOffset(offset + 1 + lengthLength + length);
        return _decodeChildren(data, offset, offset + 1 + lengthLength, lengthLength + length);
    }
    else if (data[offset] >= 0xc0) {
        const length = data[offset] - 0xc0;
        checkOffset(offset + 1 + length);
        return _decodeChildren(data, offset, offset + 1, length);
    }
    else if (data[offset] >= 0xb8) {
        const lengthLength = data[offset] - 0xb7;
        checkOffset(offset + 1 + lengthLength);
        const length = unarrayifyInteger(data, offset + 1, lengthLength);
        checkOffset(offset + 1 + lengthLength + length);
        const result = hexlify(data.slice(offset + 1 + lengthLength, offset + 1 + lengthLength + length));
        return { consumed: (1 + lengthLength + length), result: result };
    }
    else if (data[offset] >= 0x80) {
        const length = data[offset] - 0x80;
        checkOffset(offset + 1 + length);
        const result = hexlify(data.slice(offset + 1, offset + 1 + length));
        return { consumed: (1 + length), result: result };
    }
    return { consumed: 1, result: hexlifyByte(data[offset]) };
}
/**
 *  Decodes %%data%% into the structured data it represents.
 */
export function decodeRlp(_data) {
    const data = getBytes(_data, "data");
    const decoded = _decode(data, 0);
    assertArgument(decoded.consumed === data.length, "unexpected junk after rlp payload", "data", _data);
    return decoded.result;
}
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