chore: added pagination for commitments

contracts/RlnBase.sol

@@ -40,6 +40,9 @@ error InsufficientContractBalance();
 /// Invalid proof
 error InvalidProof();
 
+/// Invalid pagination query
+error InvalidPaginationQuery(uint256 startIndex, uint256 endIndex);
+
 abstract contract RlnBase {
     /// @notice The Field
     uint256 public constant Q = 21888242871839275222246405745257275088548364400416034343698204186575808495617;
@@ -64,6 +67,9 @@ abstract contract RlnBase {
     /// maps from idCommitment to their index in the set
     mapping(uint256 => uint256) public members;
 
+    /// @notice the index to commitment mapping
+    mapping(uint256 => uint256) public indexToCommitment;
+
     /// @notice The membership status of each member
     mapping(uint256 => bool) public memberExists;
 
@@ -121,6 +127,7 @@ abstract contract RlnBase {
         if (idCommitmentIndex >= SET_SIZE) revert FullTree();
 
         members[idCommitment] = idCommitmentIndex;
+        indexToCommitment[idCommitmentIndex] = idCommitment;
         memberExists[idCommitment] = true;
         BinaryIMT.insert(imtData, idCommitment);
         stakedAmounts[idCommitment] = stake;
@@ -167,6 +174,7 @@ abstract contract RlnBase {
         // delete member
         uint256 index = members[idCommitment];
         members[idCommitment] = 0;
+        indexToCommitment[index] = 0;
         memberExists[idCommitment] = false;
         stakedAmounts[idCommitment] = 0;
         // TODO: remove from IMT
@@ -218,4 +226,15 @@ abstract contract RlnBase {
     function root() external view returns (uint256) {
         return imtData.root;
     }
+
+    function getCommitments(uint256 startIndex, uint256 endIndex) public view returns (uint256[] memory) {
+        if (startIndex >= endIndex) revert InvalidPaginationQuery(startIndex, endIndex);
+        if (endIndex > idCommitmentIndex) revert InvalidPaginationQuery(startIndex, endIndex);
+
+        uint256[] memory commitments = new uint256[](endIndex - startIndex);
+        for (uint256 i = startIndex; i < endIndex; i++) {
+            commitments[i - startIndex] = indexToCommitment[i];
+        }
+        return commitments;
+    }
 }

docs/index.md

@@ -125,6 +125,14 @@ error InvalidProof()
 
 Invalid proof
 
+## InvalidPaginationQuery
+
+```solidity
+error InvalidPaginationQuery(uint256 startIndex, uint256 endIndex)
+```
+
+Invalid pagination query
+
 ## RlnBase
 
 ### Q
@@ -185,6 +193,14 @@ mapping(uint256 => uint256) members
 The membership status of each member
 maps from idCommitment to their index in the set
 
+### indexToCommitment
+
+```solidity
+mapping(uint256 => uint256) indexToCommitment
+```
+
+the index to commitment mapping
+
 ### memberExists
 
 ```solidity
@@ -371,6 +387,12 @@ _Groth16 proof verification_
 function root() external view returns (uint256)
 ```
 
+### getCommitments
+
+```solidity
+function getCommitments(uint256 startIndex, uint256 endIndex) public view returns (uint256[])
+```
+
 ## Pairing
 
 ### G1Point

test/Rln.t.sol

@@ -38,8 +38,8 @@ contract RlnTest is Test {
         vm.assume(rln.isValidCommitment(idCommitment));
         rln.register{value: MEMBERSHIP_DEPOSIT}(idCommitment);
         assertEq(rln.stakedAmounts(idCommitment), MEMBERSHIP_DEPOSIT);
-        // assertEq(rln.memberExists(idCommitment), true);
-        // assertEq(rln.members(idCommitment), 0);
+        assertEq(rln.memberExists(idCommitment), true);
+        assertEq(rln.members(idCommitment), 0);
     }
 
     function test__InvalidRegistration__DuplicateCommitment(uint256 idCommitment) public {
@@ -220,4 +220,30 @@ contract RlnTest is Test {
 
         assertEq(rln.root(), 5210724218081541877101688952118136930297124697603087561558225712176057209122);
     }
+
+    function test__paginationCommitments() public {
+        uint256[] memory idCommitments = new uint256[](10);
+        idCommitments[0] = 19143711682366759980911001457853255795836264632723844153354310748778748156460;
+        idCommitments[1] = 16984765328852711772291441487727981184905800779020079168989152080434188364678;
+        idCommitments[2] = 10972315136095845343447418815139813428649316683283020632475608655814722712541;
+        idCommitments[3] = 2709631781045191277266130708832884002577134582503944059038971337978087532997;
+        idCommitments[4] = 8255654132980945447086418574686169461187805238257784695584517016324877809505;
+        idCommitments[5] = 20291701150251695209910387548168084091751201746043024067531503187703236470983;
+        idCommitments[6] = 11817872986033932471261438074921403500882957864164537515599299873089437746577;
+        idCommitments[7] = 18475838919635792169148272767721284591038756730004222133003018558598315558783;
+        idCommitments[8] = 10612118277928165031660389522171737855229037400929675201853245490188277695983;
+        idCommitments[9] = 17318633845296358766427229711888486415250435256643711009388405482885762601797;
+
+        vm.pauseGasMetering();
+        for (uint256 i = 0; i < idCommitments.length; i++) {
+            rln.register{value: MEMBERSHIP_DEPOSIT}(idCommitments[i]);
+        }
+        vm.resumeGasMetering();
+
+        uint256[] memory commitments = rln.getCommitments(0, 10);
+        assertEq(commitments.length, 10);
+        for (uint256 i = 0; i < commitments.length; i++) {
+            assertEq(commitments[i], idCommitments[i]);
+        }
+    }
 }