feat: add function selector to cli to make it easier for to call functions

docs/docs/dev_docs/cli/main.md

@@ -135,4 +135,10 @@ The `call` command calls a read-only method on a contract, one that will not gen
 - `--contract-artifact` - The artifact of the contract we are calling.
 - `--contract-address` - The address of the deployed contract
 
-As you can see from the result, this address has a public balance of 543, as expected.
+As you can see from the result, this address has a public balance of 543, as expected.
+
+## Compute Function Selector
+`aztec-cli --compute-selector <signature e.g. foo(Field,Field)>` gives the function selector.  
+
+## Inspect Contract
+`aztec-cli --compute-selector <json artifact file e.g. artifacts/token_contract.json>` gives the list of all callable functions along with their function signature and selector.

yarn-project/cli/src/index.ts

@@ -10,7 +10,12 @@ import {
   getSchnorrAccount,
   isContractDeployed,
 } from '@aztec/aztec.js';
-import { StructType, decodeFunctionSignatureWithParameterNames } from '@aztec/foundation/abi';
+import {
+  FunctionSelector,
+  StructType,
+  decodeFunctionSignature,
+  decodeFunctionSignatureWithParameterNames,
+} from '@aztec/foundation/abi';
 import { JsonStringify } from '@aztec/foundation/json-rpc';
 import { DebugLogger, LogFn } from '@aztec/foundation/log';
 import { sleep } from '@aztec/foundation/sleep';
@@ -677,11 +682,24 @@ export function getProgram(log: LogFn, debugLogger: DebugLogger): Command {
         log(`No external functions found for contract ${contractArtifact.name}`);
       }
       for (const fn of contractFns) {
-        const signature = decodeFunctionSignatureWithParameterNames(fn.name, fn.parameters);
-        log(`${fn.functionType} ${signature}`);
+        const signatureWithParameterNames = decodeFunctionSignatureWithParameterNames(fn.name, fn.parameters);
+        const signature = decodeFunctionSignature(fn.name, fn.parameters);
+        const selector = FunctionSelector.fromSignature(signature);
+        log(
+          `${fn.functionType} ${signatureWithParameterNames} \n\tfunction signature: ${signature}\n\tselector: ${selector}`,
+        );
       }
     });
 
+  program
+    .command('compute-selector')
+    .description('Given a function signature, it computes a selector')
+    .argument('<functionSignature>', 'Function signature to compute selector for e.g. foo(Field)')
+    .action((functionSignature: string) => {
+      const selector = FunctionSelector.fromSignature(functionSignature);
+      log(`${selector}`);
+    });
+
   compileContract(program, 'compile', log);
   generateTypescriptInterface(program, 'generate-typescript', log);
   generateNoirInterface(program, 'generate-noir-interface', log);