init

lib/Permit.js

@@ -0,0 +1,43 @@
+const { EIP712Signer } = require('@ticket721/e712')
+
+const Permit = [
+  { name: 'owner', type: 'address' },
+  { name: 'spender', type: 'address' },
+  { name: 'value', type: 'uint256' },
+  { name: 'nonce', type: 'uint256' },
+  { name: 'deadline', type: 'uint256' }
+]
+
+class PermitSigner extends EIP712Signer {
+  constructor(_domain, _permitArgs) {
+    super(_domain, ['Permit', Permit])
+    this.permitArgs = _permitArgs
+  }
+
+  // Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)
+  setPermitInfo(_permitArgs) {
+    this.permitArgs = _permitArgs
+  }
+
+  getPayload() {
+    return this.generatePayload(this.permitArgs, 'Permit')
+  }
+
+  async getSignature(privateKey) {
+    const payload = this.getPayload()
+    const { hex, v, r, s } = await this.sign(privateKey, payload)
+    return {
+      hex,
+      v,
+      r: '0x' + r,
+      s: '0x' + s
+    }
+  }
+
+  getSignerAddress(permitArgs, signature) {
+    const originalPayload = this.generatePayload(permitArgs, 'Permit')
+    return this.verify(originalPayload, signature)
+  }
+}
+
+module.exports = { PermitSigner }