core-utils: add `toJSON` methods on batch primitives

Allows for easy serialization and display in frontends
or for data collection

.changeset/soft-dogs-hide.md

+---
+'@eth-optimism/core-utils': patch
+---
+
+Add toJSON methods to the batch primitives

packages/core-utils/src/optimism/batch-encoding.ts

@@ -149,6 +149,15 @@ export class Context extends Struct {
     this.blockNumber = br.readU40BE()
     return this
   }
+
+  toJSON() {
+    return {
+      numSequencedTransactions: this.numSequencedTransactions,
+      numSubsequentQueueTransactions: this.numSubsequentQueueTransactions,
+      timestamp: this.timestamp,
+      blockNumber: this.blockNumber,
+    }
+  }
 }
 
 // transaction
@@ -229,6 +238,27 @@ export class BatchedTx extends Struct {
     )
   }
 
+  toJSON() {
+    if (!this.tx) {
+      this.tx = parse(this.raw)
+    }
+
+    return {
+      nonce: this.tx.nonce,
+      gasPrice: this.tx.gasPrice.toString(),
+      gasLimit: this.tx.gasLimit.toString(),
+      to: this.tx.to,
+      value: this.tx.value.toString(),
+      data: this.tx.data,
+      v: this.tx.v,
+      r: this.tx.r,
+      s: this.tx.s,
+      chainId: this.tx.chainId,
+      hash: this.tx.hash,
+      from: this.tx.from,
+    }
+  }
+
   // TODO: inconsistent API with toTransaction
   // but unnecessary right now
   // this should be fromHexTransaction
@@ -390,4 +420,13 @@ export class SequencerBatch extends Struct {
   toHex(): string {
     return '0x' + this.encode().toString('hex')
   }
+
+  toJSON() {
+    return {
+      shouldStartAtElement: this.shouldStartAtElement,
+      totalElementsToAppend: this.totalElementsToAppend,
+      contexts: this.contexts.map((c) => c.toJSON()),
+      transactions: this.transactions.map((tx) => tx.toJSON()),
+    }
+  }
 }