Allow users to specify the contracts backend in abi-gen

3 files changed, 28 insertions, 8 deletions

diff --git a/packages/abi-gen/src/index.ts b/packages/abi-gen/src/index.ts
index bc5a974a9..d34d74cdf 100644
--- a/packages/abi-gen/src/index.ts
+++ b/packages/abi-gen/src/index.ts
@@ -11,13 +11,14 @@ import * as yargs from 'yargs';
 import toSnakeCase = require('to-snake-case');
 import * as Web3 from 'web3';
 
-import { ContextData, ParamKind } from './types';
+import { ContextData, ContractsBackend, ParamKind } from './types';
 import { utils } from './utils';
 
 const ABI_TYPE_CONSTRUCTOR = 'constructor';
 const ABI_TYPE_METHOD = 'function';
 const ABI_TYPE_EVENT = 'event';
 const DEFAULT_NETWORK_ID = 50;
+const DEFAULT_BACKEND = 'web3';
 
 const args = yargs
     .option('abis', {
@@ -43,6 +44,12 @@ const args = yargs
         demandOption: true,
         normalize: true,
     })
+    .option('backend', {
+        describe: 'Which backend do you plan to use. Either web3 or ethers',
+        type: 'string',
+        choices: [ContractsBackend.Web3, ContractsBackend.Ethers],
+        default: DEFAULT_BACKEND,
+    })
     .option('network-id', {
         describe: 'ID of the network where contract ABIs are nested in artifacts',
         type: 'number',
@@ -73,8 +80,8 @@ function writeOutputFile(name: string, renderedTsCode: string): void {
     utils.log(`Created: ${chalk.bold(filePath)}`);
 }
 
-Handlebars.registerHelper('parameterType', utils.solTypeToTsType.bind(utils, ParamKind.Input));
-Handlebars.registerHelper('returnType', utils.solTypeToTsType.bind(utils, ParamKind.Output));
+Handlebars.registerHelper('parameterType', utils.solTypeToTsType.bind(utils, ParamKind.Input, args.backend));
+Handlebars.registerHelper('returnType', utils.solTypeToTsType.bind(utils, ParamKind.Output, args.backend));
 
 if (args.partials) {
     registerPartials(args.partials);
diff --git a/packages/abi-gen/src/types.ts b/packages/abi-gen/src/types.ts
index e82ab824b..402e0105e 100644
--- a/packages/abi-gen/src/types.ts
+++ b/packages/abi-gen/src/types.ts
@@ -12,6 +12,11 @@ export enum AbiType {
     Fallback = 'fallback',
 }
 
+export enum ContractsBackend {
+    Web3 = 'web3',
+    Ethers = 'ethers',
+}
+
 export interface Method extends Web3.MethodAbi {
     singleReturnValue: boolean;
 }
diff --git a/packages/abi-gen/src/utils.ts b/packages/abi-gen/src/utils.ts
index 14255643a..dc2c5390e 100644
--- a/packages/abi-gen/src/utils.ts
+++ b/packages/abi-gen/src/utils.ts
@@ -3,14 +3,14 @@ import * as _ from 'lodash';
 import * as path from 'path';
 import * as Web3 from 'web3';
 
-import { AbiType, ParamKind } from './types';
+import { AbiType, ContractsBackend, ParamKind } from './types';
 
 export const utils = {
-    solTypeToTsType(paramKind: ParamKind, solType: string): string {
+    solTypeToTsType(paramKind: ParamKind, backend: ContractsBackend, solType: string): string {
         const trailingArrayRegex = /\[\d*\]$/;
         if (solType.match(trailingArrayRegex)) {
             const arrayItemSolType = solType.replace(trailingArrayRegex, '');
-            const arrayItemTsType = utils.solTypeToTsType(paramKind, arrayItemSolType);
+            const arrayItemTsType = utils.solTypeToTsType(paramKind, backend, arrayItemSolType);
             const arrayTsType = utils.isUnionType(arrayItemTsType)
                 ? `Array<${arrayItemTsType}>`
                 : `${arrayItemTsType}[]`;
@@ -24,13 +24,21 @@ export const utils = {
                 { regex: '^bytes\\d*$', tsType: 'string' },
             ];
             if (paramKind === ParamKind.Input) {
-                // web3 allows to pass those an non-bignumbers and that's nice
-                // but it always returns stuff as BigNumbers
+                // web3 and ethers allow to pass those as numbers instead of bignumbers
                 solTypeRegexToTsType.unshift({
                     regex: '^u?int(8|16|32)?$',
                     tsType: 'number|BigNumber',
                 });
             }
+            if (backend === ContractsBackend.Ethers) {
+                if (paramKind === ParamKind.Output) {
+                    // ethers-contracts automatically converts small BigNumbers to numbers
+                    solTypeRegexToTsType.unshift({
+                        regex: '^u?int(8|16|32|48)?$',
+                        tsType: 'number',
+                    });
+                }
+            }
             for (const regexAndTxType of solTypeRegexToTsType) {
                 const { regex, tsType } = regexAndTxType;
                 if (solType.match(regex)) {