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Diffstat (limited to 'packages/0x.js/src/utils/filter_utils.ts')
-rw-r--r-- | packages/0x.js/src/utils/filter_utils.ts | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/packages/0x.js/src/utils/filter_utils.ts b/packages/0x.js/src/utils/filter_utils.ts new file mode 100644 index 000000000..e09a95a6e --- /dev/null +++ b/packages/0x.js/src/utils/filter_utils.ts @@ -0,0 +1,82 @@ +import * as _ from 'lodash'; +import * as Web3 from 'web3'; +import * as uuid from 'uuid/v4'; +import * as ethUtil from 'ethereumjs-util'; +import * as jsSHA3 from 'js-sha3'; +import {ContractEvents, IndexedFilterValues, SubscriptionOpts} from '../types'; + +const TOPIC_LENGTH = 32; + +export const filterUtils = { + generateUUID(): string { + return uuid(); + }, + getFilter(address: string, eventName: ContractEvents, + indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi, + subscriptionOpts?: SubscriptionOpts): Web3.FilterObject { + const eventAbi = _.find(abi, {name: eventName}) as Web3.EventAbi; + const eventSignature = filterUtils.getEventSignatureFromAbiByName(eventAbi, eventName); + const topicForEventSignature = ethUtil.addHexPrefix(jsSHA3.keccak256(eventSignature)); + const topicsForIndexedArgs = filterUtils.getTopicsForIndexedArgs(eventAbi, indexFilterValues); + const topics = [topicForEventSignature, ...topicsForIndexedArgs]; + let filter: Web3.FilterObject = { + address, + topics, + }; + if (!_.isUndefined(subscriptionOpts)) { + filter = { + ...subscriptionOpts, + ...filter, + }; + } + return filter; + }, + getEventSignatureFromAbiByName(eventAbi: Web3.EventAbi, eventName: ContractEvents): string { + const types = _.map(eventAbi.inputs, 'type'); + const signature = `${eventAbi.name}(${types.join(',')})`; + return signature; + }, + getTopicsForIndexedArgs(abi: Web3.EventAbi, indexFilterValues: IndexedFilterValues): Array<string|null> { + const topics: Array<string|null> = []; + for (const eventInput of abi.inputs) { + if (!eventInput.indexed) { + continue; + } + if (_.isUndefined(indexFilterValues[eventInput.name])) { + // Null is a wildcard topic in a JSON-RPC call + topics.push(null); + } else { + const value = indexFilterValues[eventInput.name] as string; + const buffer = ethUtil.toBuffer(value); + const paddedBuffer = ethUtil.setLengthLeft(buffer, TOPIC_LENGTH); + const topic = ethUtil.bufferToHex(paddedBuffer); + topics.push(topic); + } + } + return topics; + }, + matchesFilter(log: Web3.LogEntry, filter: Web3.FilterObject): boolean { + if (!_.isUndefined(filter.address) && log.address !== filter.address) { + return false; + } + if (!_.isUndefined(filter.topics)) { + return filterUtils.matchesTopics(log.topics, filter.topics); + } + return true; + }, + matchesTopics(logTopics: string[], filterTopics: Array<string[]|string|null>): boolean { + const matchesTopic = _.zipWith(logTopics, filterTopics, filterUtils.matchesTopic.bind(filterUtils)); + const matchesTopics = _.every(matchesTopic); + return matchesTopics; + }, + matchesTopic(logTopic: string, filterTopic: string[]|string|null): boolean { + if (_.isArray(filterTopic)) { + return _.includes(filterTopic, logTopic); + } + if (_.isString(filterTopic)) { + return filterTopic === logTopic; + } + // null topic is a wildcard + return true; + }, +}; |