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@0x/contracts-exchange-libs: Remove unecessary checks for zero

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denominator.
`@0x/contracts-exchange-libs`: `LibMath` tests from `@0x/contracts-exchange` into this package.
`@0x/contracts-exchange-libs`: Adjust logic in reference functions to be
closer to solidity implementation.
This commit is contained in:
Lawrence Forman 2019-08-01 15:13:40 -04:00
parent 4600a656d1
commit f791cd3a37
5 changed files with 161 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
contracts/exchange-libs/CHANGELOG.json
View File

@ -57,6 +57,14 @@
{
"note": "Add reference functions for `LibMath` and `LibFillResults`",
"pr": "TODO"
},
{
"note": "Bring in revamped `LibMath` tests from the `contracts-exchange` package.",
"pr": "TODO"
},
{
"note": "Remove unecessary zero-denominator checks in `LibMath`.",
"pr": "TODO"
}
]
},

16
contracts/exchange-libs/contracts/src/LibMath.sol
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@ -41,10 +41,6 @@ contract LibMath is
pure
returns (uint256 partialAmount)
{
if (denominator == 0) {
LibRichErrors._rrevert(LibMathRichErrors.DivisionByZeroError());
}
if (_isRoundingErrorFloor(
numerator,
denominator,
@ -79,10 +75,6 @@ contract LibMath is
pure
returns (uint256 partialAmount)
{
if (denominator == 0) {
LibRichErrors._rrevert(LibMathRichErrors.DivisionByZeroError());
}
if (_isRoundingErrorCeil(
numerator,
denominator,
@ -122,10 +114,6 @@ contract LibMath is
pure
returns (uint256 partialAmount)
{
if (denominator == 0) {
LibRichErrors._rrevert(LibMathRichErrors.DivisionByZeroError());
}
partialAmount = _safeDiv(
_safeMul(numerator, target),
denominator
@ -147,10 +135,6 @@ contract LibMath is
pure
returns (uint256 partialAmount)
{
if (denominator == 0) {
LibRichErrors._rrevert(LibMathRichErrors.DivisionByZeroError());
}
// _safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
// ceil(a / b) = floor((a + b - 1) / b)
// To implement `ceil(a / b)` using _safeDiv.

34
contracts/exchange-libs/contracts/test/TestLibs.sol
View File

@ -73,6 +73,40 @@ contract TestLibs is
return partialAmount;
}
function safeGetPartialAmountFloor(
uint256 numerator,
uint256 denominator,
uint256 target
)
public
pure
returns (uint256 partialAmount)
{
partialAmount = _safeGetPartialAmountFloor(
numerator,
denominator,
target
);
return partialAmount;
}
function safeGetPartialAmountCeil(
uint256 numerator,
uint256 denominator,
uint256 target
)
public
pure
returns (uint256 partialAmount)
{
partialAmount = _safeGetPartialAmountCeil(
numerator,
denominator,
target
);
return partialAmount;
}
function isRoundingErrorFloor(
uint256 numerator,
uint256 denominator,

26
contracts/exchange-libs/src/reference_functions.ts
View File

@ -21,8 +21,11 @@ export function isRoundingErrorFloor(
if (numerator.eq(0) || target.eq(0)) {
return false;
}
const remainder = numerator.multipliedBy(target).mod(denominator);
return safeMul(new BigNumber(1000), remainder).gte(safeMul(numerator, target));
const remainder = numerator.times(target).mod(denominator);
// Need to do this separately because solidity evaluates RHS of the comparison expression first.
const rhs = safeMul(numerator, target);
const lhs = safeMul(new BigNumber(1000), remainder);
return lhs.gte(rhs);
}
export function isRoundingErrorCeil(
@ -36,9 +39,12 @@ export function isRoundingErrorCeil(
if (numerator.eq(0) || target.eq(0)) {
return false;
}
let remainder = numerator.multipliedBy(target).mod(denominator);
let remainder = numerator.times(target).mod(denominator);
remainder = safeSub(denominator, remainder).mod(denominator);
return safeMul(new BigNumber(1000), remainder).gte(safeMul(numerator, target));
// Need to do this separately because solidity evaluates RHS of the comparison expression first.
const rhs = safeMul(numerator, target);
const lhs = safeMul(new BigNumber(1000), remainder);
return lhs.gte(rhs);
}
export function safeGetPartialAmountFloor(
@ -46,9 +52,6 @@ export function safeGetPartialAmountFloor(
denominator: BigNumber,
target: BigNumber,
): BigNumber {
if (denominator.eq(0)) {
throw new LibMathRevertErrors.DivisionByZeroError();
}
if (isRoundingErrorFloor(numerator, denominator, target)) {
throw new LibMathRevertErrors.RoundingError(numerator, denominator, target);
}
@ -63,9 +66,6 @@ export function safeGetPartialAmountCeil(
denominator: BigNumber,
target: BigNumber,
): BigNumber {
if (denominator.eq(0)) {
throw new LibMathRevertErrors.DivisionByZeroError();
}
if (isRoundingErrorCeil(numerator, denominator, target)) {
throw new LibMathRevertErrors.RoundingError(numerator, denominator, target);
}
@ -83,9 +83,6 @@ export function getPartialAmountFloor(
denominator: BigNumber,
target: BigNumber,
): BigNumber {
if (denominator.eq(0)) {
throw new LibMathRevertErrors.DivisionByZeroError();
}
return safeDiv(
safeMul(numerator, target),
denominator,
@ -97,9 +94,6 @@ export function getPartialAmountCeil(
denominator: BigNumber,
target: BigNumber,
): BigNumber {
if (denominator.eq(0)) {
throw new LibMathRevertErrors.DivisionByZeroError();
}
return safeDiv(
safeAdd(
safeMul(numerator, target),

109
contracts/exchange-libs/test/lib_math.ts Normal file
View File

@ -0,0 +1,109 @@
import {
blockchainTests,
describe,
testCombinatoriallyWithReferenceFunc,
uint256Values,
} from '@0x/contracts-test-utils';
import { BigNumber } from '@0x/utils';
import * as _ from 'lodash';
import { artifacts, ReferenceFunctions, TestLibsContract } from '../src';
const CHAIN_ID = 1337;
blockchainTests('LibMath', env => {
let libsContract: TestLibsContract;
before(async () => {
libsContract = await TestLibsContract.deployFrom0xArtifactAsync(
artifacts.TestLibs,
env.provider,
env.txDefaults,
new BigNumber(CHAIN_ID),
);
});
// Wrap a reference function with identical arguments in a promise.
function createAsyncReferenceFunction<T>(
ref: (...args: any[]) => T,
): (...args: any[]) => Promise<T> {
return async (...args: any[]): Promise<T> => {
return ref(...args);
};
}
function createContractTestFunction<T>(
name: string,
): (...args: any[]) => Promise<T> {
return async (...args: any[]): Promise<T> => {
const method = (libsContract as any)[name] as { callAsync: (...args: any[]) => Promise<T> };
return method.callAsync(...args);
};
}
describe('getPartialAmountFloor', () => {
describe.optional('combinatorial tests', () => {
testCombinatoriallyWithReferenceFunc(
'getPartialAmountFloor',
createAsyncReferenceFunction(ReferenceFunctions.getPartialAmountFloor),
createContractTestFunction('getPartialAmountFloor'),
[uint256Values, uint256Values, uint256Values],
);
});
});
describe('getPartialAmountCeil', () => {
describe.optional('combinatorial tests', () => {
testCombinatoriallyWithReferenceFunc(
'getPartialAmountCeil',
createAsyncReferenceFunction(ReferenceFunctions.getPartialAmountCeil),
createContractTestFunction('getPartialAmountCeil'),
[uint256Values, uint256Values, uint256Values],
);
});
});
describe('safeGetPartialAmountFloor', () => {
describe.optional('combinatorial tests', () => {
testCombinatoriallyWithReferenceFunc(
'safeGetPartialAmountFloor',
createAsyncReferenceFunction(ReferenceFunctions.safeGetPartialAmountFloor),
createContractTestFunction('safeGetPartialAmountFloor'),
[uint256Values, uint256Values, uint256Values],
);
});
});
describe('safeGetPartialAmountCeil', () => {
describe.optional('combinatorial tests', () => {
testCombinatoriallyWithReferenceFunc(
'safeGetPartialAmountCeil',
createAsyncReferenceFunction(ReferenceFunctions.safeGetPartialAmountCeil),
createContractTestFunction('safeGetPartialAmountCeil'),
[uint256Values, uint256Values, uint256Values],
);
});
});
describe('isRoundingErrorFloor', () => {
describe.optional('combinatorial tests', () => {
testCombinatoriallyWithReferenceFunc(
'isRoundingErrorFloor',
createAsyncReferenceFunction(ReferenceFunctions.isRoundingErrorFloor),
createContractTestFunction('isRoundingErrorFloor'),
[uint256Values, uint256Values, uint256Values],
);
});
});
describe('isRoundingErrorCeil', () => {
describe.optional('combinatorial tests', () => {
testCombinatoriallyWithReferenceFunc(
'isRoundingErrorCeil',
createAsyncReferenceFunction(ReferenceFunctions.isRoundingErrorCeil),
createContractTestFunction('isRoundingErrorCeil'),
[uint256Values, uint256Values, uint256Values],
);
});
});
});