Indexer

Indexers are used by makers to signal their interest in trading and by takers to query for makers with mutual trading interest. Locators are strings used by takers to connect to makers. In the case of Servers, locators are URLs, and in the case of Delegates, locators are contract addresses.
Indexer Client
Add the @airswap/protocols package to your application.
$ yarn add @airswap/protocols
Import the Indexer client.
import { Indexer } from '@airswap/protocols'
constructor
Create a new Indexer client.
public constructor(
  chainId = chainIds.RINKEBY,
  walletOrProvider?: ethers.Wallet | ethers.providers.Provider
)
Param
Type
Optionality
Description
​
chainId
string
optional
Ethereum chain ID of the network to connect to, either 1 or 4.
​
walletOrProvider
`ethers.Wallet
ethers.providers.Provider`
optional
Ethers wallet or provider to use for the contract instance.
Example Create a client for the Rinkeby Indexer using the default provider.
const indexer = new Indexer();
Example Create a client for the Mainnet Indexer using an INFURA provider.
import { chainIds } from '@airswap/constants'
const provider = new ethers.providers.InfuraProvider(...)
const indexer = new Indexer(chainIds.MAINNET, provider);
getLocators
Get a list of string locators by token pair.
public async getLocators(
  signerToken: string,
  senderToken: string,
  protocol = protocols.SERVER,
  limit = 10,
  cursor = INDEX_HEAD
)
): Promise<LocatorResult>
Param
Type
Optionality
Description
signerToken
string
required
Address of a token for the signer side of a trade.
senderToken
string
required
Address of a token for the sender side of a trade.
protocol
bytes2
optional default protocols.SERVER
Protocol to query e.g. protocols.SERVER or protocols.DELEGATE.
limit
number
optional default 10
Maximum number of results to query.
cursor
address
optional default head
Cursor from which to start the query.
Example Query rinkeby Servers for those selling DAI for WETH. Locators are Server URLs.
const indexer = new Indexer();
const { locators } = await indexer.getLocators(signerToken, senderToken);
Example Query rinkeby Delegates for those selling DAI for WETH. Locators are Delegate contract addresses.
import { rinkebyTokens, protocols } from `@airswap/constants`
const indexer = new Indexer();
const { locators } = await indexer.getLocators(signerToken, senderToken, protocols.DELEGATE);
Solidity
See Contract Deployments for the latest mainnet and rinkeby Indexer deployments.
Indexer Contract
An Indexer is a smart contract to discover trading parties by token pair. View the code on GitHub.
constructor
Create a new Indexer contract.
constructor(
  address indexerStakingToken
) public
Param
Type
Description
indexerStakingToken
address
Address of the token required for staking. Must be a standard ERC20 contract.
createIndex
If none exists, deploy a new Index contract for the given token pair and return its address. If the requested Index already exists, the function just returns its address.
function createIndex(
  address signerToken,
  address senderToken,
  bytes2  protocol
) external returns (address)
Param
Type
Description
signerToken
address
Address of the token transferred from a signer in a trade.
senderToken
address
Address of the token transferred from a sender in a trade.
protocol
bytes2
Identifier for different locator versions ie http makers, delegates.
When a new Index is deployed, createIndex emits a CreateIndex event.
event CreateIndex(
  address signerToken,
  address senderToken,
  bytes2 protocol
);
addTokenToBlacklist
Add a token to the blacklist. Markets that include a blacklisted token cannot have intents to trade set on them and cannot have locators fetched for them.
function addTokenToBlacklist(
  address token
) external onlyOwner
Param
Type
Description
token
address
Address of the token to blacklist.
A successful addTokenToBlacklist emits a AddTokenToBlacklist event.
event AddTokenToBlacklist(
  address token
);
removeTokenFromBlacklist
Remove a token from the blacklist. Markets that include a blacklisted token cannot have intents to trade set on them and cannot have locators fetched for them.
function removeTokenFromBlacklist(
  address token
) external onlyOwner
Param
Type
Description
token
address
The address of the token to remove.
A successful removeTokenFromBlacklist emits a RemoveTokenFromBlacklist event.
event RemoveTokenFromBlacklist(
  address token
);
setIntent
Stake tokens to the Indexer and set an intent to trade. If the caller already has an intent on the specified Index, then the intent is updated to reflect the new stakingAmount and locator.
function setIntent(
  address signerToken,
  address senderToken,
  bytes2 protocol,
  uint256 stakingAmount,
  bytes32 locator
) external
Param
Type
Description
signerToken
address
Signer token of the Index being staked.
senderToken
address
Sender token of the Index being staked.
protocol
bytes2
Identifies protocol to communicate with locator.
stakingAmount
uint256
Amount of stakingToken to stake.
locator
bytes32
Arbitrary data. Often an address in the first 20 bytes.
A successful setIntent emits a Stake event. The underlying Index emits an SetLocator event.
event Stake(
  address indexed staker,
  address indexed signerToken,
  address indexed senderToken,
  bytes2 protocol,
  uint256 stakeAmount
);
Revert Reason
Scenario
INDEX_DOES_NOT_EXIST
There is no index for the token pair.
LOCATOR_NOT_WHITELISTED
The locator was not found on the whitelist.
PAIR_IS_BLACKLISTED
One or both of the tokens are blacklisted.
UNABLE_TO_STAKE
The staking amount was not transferred.
ENTRY_ALREADY_EXISTS
Entry does not exist for the message sender.
unsetIntent
Unset an intent to trade and return staked tokens to the sender.
function unsetIntent(
  address signerToken,
  address senderToken,
  bytes2 protocol
) external
Param
Type
Description
signerToken
address
Signer token of the Index being unstaked.
senderToken
address
Sender token of the Index being unstaked.
protocol
bytes2
Identifies protocol to communicate with locator.
A successful unsetIntent emits an Unstake event. The underlying Index emits an UnsetLocator event.
event Unstake(
  address indexed staker,
  address indexed signerToken,
  address indexed senderToken,
  bytes2 protocol,
  uint256 stakeAmount
);
Revert Reason
Scenario
INDEX_DOES_NOT_EXIST
There is no Index for the token pair.
ENTRY_DOES_NOT_EXIST
Entry does not exist for the message sender.
getLocators
Get a list of locators that have an intent to trade a token pair. Along with the locators, their corresponding staking scores are returned, and the address of the next cursor for pagination.
function getLocators(
  address signerToken,
  address senderToken,
  bytes2 protocol,
  address cursor,
  uint256 limit
) external view returns (
  bytes32[] memory locators,
  uint256[] memory scores,
  address nextCursor
) {
Param
Type
Description
signerToken
address
Address of the token that the signer transfers.
senderToken
address
Address of the token that the sender transfers.
protocol
bytes2
Identifies protocol to communicate with locator.
cursor
address
Address of the user to start from in the list.
limit
uint256
Maximum number of items to return.
getStakedAmount
Get the amount staked for a specific user, token pair, and protocol.
function getStakedAmount(
  address user,
  address signerToken,
  address senderToken,
  bytes2 protocol
) public view returns (uint256 stakedAmount) {
Param
Type
Description
user
address
The user whose stake amount is requested.
signerToken
address
The signer token of the Index they've staked on.
senderToken
address
The sender token of the Index they've staked on.
protocol
bytes2
Identifies protocol to communicate with locator.
Index Contract
An Index is a list of locators sorted by score. View the code on GitHub.
Structs
Entry
struct Entry {
  bytes32 locator;
  uint256 score;
  address prev;
  address next;
}
Functions
constructor
Create a new Index contract.
constructor() public
setLocator
Set an Locator on the Index.
function setLocator(
  address identifier,
  uint256 score,
  bytes32 locator
) external onlyOwner
Param
Type
Description
identifier
address
Onchain address identifying the owner of a locator.
score
uint256
Score for the locator being set.
locator
bytes32
Locator.
A successful setLocator emits a SetLocator event.
event SetLocator(
  address indexed identifier,
  uint256 score,
  bytes32 indexed locator
);
Revert Reason
Scenario
ENTRY_ALREADY_EXISTS
This address already has an Entry on the Index.
LOCATOR_MUST_BE_SENT
Locator must not be empty to ensure list integrity.
updateLocator
Updates an existing Locator on the Index.
function updateLocator(
  address identifier,
  uint256 score,
  bytes32 locator
) external onlyOwner
Param
Type
Description
identifier
address
Onchain address identifying the owner of a locator.
score
uint256
Score for the locator being set.
locator
bytes32
Locator.
A successful updateLocator emits a SetLocator event.
event SetLocator(
  address indexed identifier,
  uint256 score,
  bytes32 indexed locator
);
Revert Reason
Scenario
ENTRY_DOES_NOT_EXIST
This address does not has an Entry on the Index and thus cannot be updated.
LOCATOR_MUST_BE_SENT
Locator must not be empty to ensure list integrity.
unsetLocator
Unset a Locator from the Index.
function unsetLocator(
  address identifier
) external onlyOwner returns (bool) {
A successful unsetLocator emits an UnsetLocator event.
event UnsetLocator(
  address event identifier
);
Param
Type
Description
identifier
address
Onchain address identifying the owner of a locator.
Revert Reason
Scenario
ENTRY_DOES_NOT_EXIST
This address does not have an Entry on the Index.
getScore
Gets the score for a given identifier.
function getScore(
  address identifier
) external view returns (uint256)
Param
Type
Description
identifier
address
Onchain address identifying the owner of a locator.
getLocator
Gets the locator as bytes32 for a given identifier.
function getLocator(
  address identifier
) external view returns (bytes32)
Param
Type
Description
identifier
address
Onchain address identifying the owner of a locator.
getLocators
Get a Range of Locators.
function getLocators(
   address cursor,
   uint256 limit
) external view returns (bytes32[] memory locators, uint256[] memory scores, address nextCursor) {
Param
Type
Description
cursor
address
Cursor to start with.
limit
uint256
Maximum number of locators to return.

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Param	Type	Optionality	Description
`signerToken`	`string`	`required`	Address of a token for the signer side of a trade.
`senderToken`	`string`	`required`	Address of a token for the sender side of a trade.
`protocol`	`bytes2`	`optional` default `protocols.SERVER`	Protocol to query e.g. `protocols.SERVER` or `protocols.DELEGATE`.
`limit`	`number`	`optional` default `10`	Maximum number of results to query.
`cursor`	`address`	`optional` default `head`	Cursor from which to start the query.

Param	Type	Description
`signerToken`	`address`	Signer token of the Index being staked.
`senderToken`	`address`	Sender token of the Index being staked.
`protocol`	`bytes2`	Identifies protocol to communicate with locator.
`stakingAmount`	`uint256`	Amount of stakingToken to stake.
`locator`	`bytes32`	Arbitrary data. Often an address in the first 20 bytes.

Param	Type	Description
`signerToken`	`address`	Address of the token that the signer transfers.
`senderToken`	`address`	Address of the token that the sender transfers.
`protocol`	`bytes2`	Identifies protocol to communicate with locator.
`cursor`	`address`	Address of the user to start from in the list.
`limit`	`uint256`	Maximum number of items to return.

Param	Type	Description
`user`	`address`	The user whose stake amount is requested.
`signerToken`	`address`	The signer token of the Index they've staked on.
`senderToken`	`address`	The sender token of the Index they've staked on.
`protocol`	`bytes2`	Identifies protocol to communicate with locator.

Indexer

Indexer Client

`constructor`

`getLocators`

Solidity

Indexer Contract

`constructor`

`createIndex`

`addTokenToBlacklist`

`removeTokenFromBlacklist`

`setIntent`

`unsetIntent`

`getLocators`

`getStakedAmount`

Index Contract

Structs

Functions

Revert Reason	Scenario
`INDEX_DOES_NOT_EXIST`	There is no index for the token pair.
`LOCATOR_NOT_WHITELISTED`	The locator was not found on the whitelist.
`PAIR_IS_BLACKLISTED`	One or both of the tokens are blacklisted.
`UNABLE_TO_STAKE`	The staking amount was not transferred.
`ENTRY_ALREADY_EXISTS`	Entry does not exist for the message sender.

Revert Reason	Scenario
`ENTRY_DOES_NOT_EXIST`	This address does not has an Entry on the Index and thus cannot be updated.
`LOCATOR_MUST_BE_SENT`	Locator must not be empty to ensure list integrity.