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openzeppelin-contracts/scripts/generate/templates/Packing.js

89 lines
2.6 KiB

const format = require('../format-lines');
const { product } = require('../../helpers');
const { SIZES } = require('./Packing.opts');
// TEMPLATE
const header = `\
pragma solidity ^0.8.20;
/**
* @dev Helper library packing and unpacking multiple values into bytesXX.
*
* Example usage:
*
* \`\`\`solidity
* library MyPacker {
* type MyType is bytes32;
*
* function _pack(address account, bytes4 selector, uint64 period) external pure returns (MyType) {
* bytes12 subpack = Packing.pack_4_8(selector, bytes8(period));
* bytes32 pack = Packing.pack_20_12(bytes20(account), subpack);
* return MyType.wrap(pack);
* }
*
* function _unpack(MyType self) external pure returns (address, bytes4, uint64) {
* bytes32 pack = MyType.unwrap(self);
* return (
* address(Packing.extract_32_20(pack, 0)),
* Packing.extract_32_4(pack, 20),
* uint64(Packing.extract_32_8(pack, 24))
* );
* }
* }
* \`\`\`
*/
// solhint-disable func-name-mixedcase
`;
const errors = `\
error OutOfRangeAccess();
`;
const pack = (left, right) => `\
function pack_${left}_${right}(bytes${left} left, bytes${right} right) internal pure returns (bytes${
left + right
} result) {
assembly ("memory-safe") {
left := and(left, shl(${256 - 8 * left}, not(0)))
right := and(right, shl(${256 - 8 * right}, not(0)))
result := or(left, shr(${8 * left}, right))
}
}
`;
const extract = (outer, inner) => `\
function extract_${outer}_${inner}(bytes${outer} self, uint8 offset) internal pure returns (bytes${inner} result) {
if (offset > ${outer - inner}) revert OutOfRangeAccess();
assembly ("memory-safe") {
result := and(shl(mul(8, offset), self), shl(${256 - 8 * inner}, not(0)))
}
}
`;
const replace = (outer, inner) => `\
function replace_${outer}_${inner}(bytes${outer} self, bytes${inner} value, uint8 offset) internal pure returns (bytes${outer} result) {
bytes${inner} oldValue = extract_${outer}_${inner}(self, offset);
assembly ("memory-safe") {
value := and(value, shl(${256 - 8 * inner}, not(0)))
result := xor(self, shr(mul(8, offset), xor(oldValue, value)))
}
}
`;
// GENERATE
module.exports = format(
header.trimEnd(),
'library Packing {',
format(
[].concat(
errors,
product(SIZES, SIZES)
.filter(([left, right]) => SIZES.includes(left + right))
.map(([left, right]) => pack(left, right)),
product(SIZES, SIZES)
.filter(([outer, inner]) => outer > inner)
.flatMap(([outer, inner]) => [extract(outer, inner), replace(outer, inner)]),
),
).trimEnd(),
'}',
);