updated readme. more complicated test

README.md

@@ -17,7 +17,7 @@ destructured into the desired data types.
 Transformations(All take an RLPItem as an arg):  
 1. `isList(RLPItem) bool` : inidicator if the encoded data is a list
 2. `toList(RLPItem) RLPItem[]` : returns a list of RLPItems
-3. `iterator(RLPITem) Iterator` : returns an `Iterator` over the RLPItem. Must be a rlp encoded list
+3. `iterator(RLPITem) Iterator` : returns an `Iterator` over the RLPItem. RLPItem must be an encoded list
 4. `toBytes(RLPItem) bytes` : returns the payload in bytes
 5. `toAddress(RLPItem) address` : returns the encoded address. Must be exactly 20 bytes.
 6. `toUint(RLPItem) uint` : returns the encoded uint. Enforced data is capped to 32 bytes.
@@ -26,9 +26,8 @@ Transformations(All take an RLPItem as an arg):
 9. `toRlpBytes(RLPItem) bytes `: returns the raw rlp encoded byte form
 10. `rlpLen(RLPItem) uint` : returns the byte length of the rlp item
 11. `payloadLen(RLPItem) uint` : returns the byte length of the data payload
-
-1. `hasNext(Iterator) bool` : indicator if there is another item to iterate on
-2. `next(Iterator) RLPItem` : returns the next `RLPItem` in the iterator
+12. `hasNext(Iterator) bool` : indicator if there is another item to iterate on
+13. `next(Iterator) RLPItem` : returns the next `RLPItem` in the iterator
 
 **Note**: The reader contract only provides only these conversion functions. All other solidity data types can be derived from
 this base. For example, a `bytes32` encoded data type is equivalent to `bytes32(toUint(RLPItem))`. Start with a uint and convert from there.
@@ -55,6 +54,16 @@ contract SomeContract {
         ls[1].toUint() // 2
         ls[2].toAddress() // 0x<Address>
     }
+
+    // lets assume rlpBytes is an encoding of [["sublist"]]
+    func someFunctionThatDemonstratesIterators(bytes memory rlpBytes) public {
+        RLPReader.Iterator memory iter = rlpBytes.toRlpItem().iterator();
+        RLPReader.Iterator memory subIter = iter.next().iterator();
+
+        // iter.hasNext() == false
+        // string(subIter.next().toBytes()) == "sublist"
+        // subIter.hasNext() == false
+    }
 }
 ```
 

contracts/Helper.sol

@@ -80,13 +80,16 @@ contract Helper {
         item.toRlpItem().iterator();
     }
 
-    // expects [[sublist],... ]
-    function nestedIteration(bytes memory item) public pure {
+    // expects [["somestring"]]
+    function nestedIteration(bytes memory item) public pure returns (string memory) {
         RLPReader.Iterator memory iter = item.toRlpItem().iterator();
-        RLPReader.RLPItem memory subList = iter.next();
+        RLPReader.Iterator memory subIter = iter.next().iterator();
+        string memory result = string(subIter.next().toBytes());
 
-        // we just care that this doesn't revert
-        subList.iterator();
+        require(!iter.hasNext());
+        require(!subIter.hasNext());
+
+        return result;
     }
 
     function toBlockHeader(bytes memory rlpHeader) public pure returns (

test/basic-tests.js

@@ -255,10 +255,9 @@ contract("RLPReader", async (accounts) => {
         if (err)
             assert.fail(null, null, "could not construct iterator out of a valid list")
 
-        data = rlp.encode([["whoooo", "hooo"]])
-        [err, _] = await catchError(helper.nestedIteration.call(toHex(data)));
-        if (err)
-            assert.fail(null, null, "could not construct iterator out of a sublist")
+        data = rlp.encode([["yeah!"]])
+        let result = await helper.nestedIteration.call(toHex(data));
+        assert(result == "yeah!", "could not retrieve the string in the sublist")
     });
 
     it("correctly iterates over an RLP list (e.g., an RLP encoded block header)", async () => {