refactor(ripple): Add Transaction encoding from JSON test

trustwallet · satoshiotomakan · Feb 7, 2025 · Jan 28, 2025 · Jan 28, 2025 · Jan 29, 2025
commit 7ca99a3262dad8703d6b1d99e71ff1f789fdadcc
@@ -5,6 +5,7 @@
 use lazy_static::lazy_static;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
+use tw_misc::serde::hashmap_as_tupple_list;
 
 pub const DEFINITIONS_JSON: &str = include_str!("../definitions/definitions.json");
 
@@ -38,10 +39,11 @@ pub struct FieldInfo {
 #[serde(rename_all = "UPPERCASE")]
 pub struct Definitions {
     pub types: HashMap<String, i16>,
+    #[serde(with = "hashmap_as_tupple_list")]
     pub fields: HashMap<String, FieldInfo>,
     pub transaction_types: HashMap<String, i16>,
 }
 
 fn parse_definitions_json() -> Definitions {
-    serde_json::from_str(DEFINITIONS_JSON).expect("registry.json expected to be valid")
+    serde_json::from_str(DEFINITIONS_JSON).expect("definitions.json expected to be valid")
 }
@@ -2,15 +2,26 @@
 //
 // Copyright © 2017 Trust Wallet.
 
+use crate::address::x_address::XAddress;
+use crate::address::RippleAddress;
 use crate::definitions::DEFINITIONS;
 use crate::encode::encoder::Encoder;
 use crate::encode::field_instance::FieldInstance;
 use crate::encode::xrpl_types::XRPLTypes;
 use serde_json::{Map as JsonMap, Value as Json};
+use std::str::FromStr;
 use tw_coin_entry::error::prelude::*;
 use tw_memory::Data;
 
 type PreProcessedObject = JsonMap<String, Json>;
+type TransactionJson = JsonMap<String, Json>;
+
+const DESTINATION_TAG: &str = "DestinationTag";
+const DESTINATION: &str = "Destination";
+const SOURCE_TAG: &str = "SourceTag";
+const ACCOUNT: &str = "Account";
+const ST_OBJECT: &str = "STObject";
+const OBJECT_END_MARKER_BYTE: u8 = 0xE1;
 
 /// Class for serializing/deserializing Indexmaps of objects.
 ///
@@ -95,12 +106,9 @@ impl STObject {
                     format!("Error encoding '{field_name}' field with '{associated_type}' type")
                 })?;
 
-            // TODO uncomment when nested STObject's supported.
-            // const ST_OBJECT: &str = "STObject";
-            // const OBJECT_END_MARKER_BYTE: u8 = 0xE1;
-            // if field_instance.associated_type == ST_OBJECT {
-            //     encoder.push_byte(OBJECT_END_MARKER_BYTE);
-            // }
+            if field_instance.associated_type == ST_OBJECT {
+                encoder.push_byte(OBJECT_END_MARKER_BYTE);
+            }
         }
 
         Ok(STObject(encoder.finish()))
@@ -119,11 +127,10 @@ impl STObject {
                 continue;
             };
 
-            // TODO consider uncommenting this to handle Source/Destination XAddresses
-            // when adding support for dapps.
-            // if let Ok(RippleAddress::X(x_addr)) = RippleAddress::from_str(value) {
-            //     Self::pre_process_x_addr(&object, &mut pre_processed, field.to_string(), x_addr)?;
-            // }
+            if let Ok(RippleAddress::X(x_addr)) = RippleAddress::from_str(value) {
+                Self::pre_process_x_addr(&object, &mut pre_processed, field.to_string(), x_addr)?;
+                continue;
+            }
 
             if field == "TransactionType" || field == "LedgerEntryType" {
                 let transaction_type_code = *DEFINITIONS
@@ -144,46 +151,39 @@ impl STObject {
         Ok(pre_processed)
     }
 
-    // TODO consider using it when adding support for dapps.
-    // type TransactionJson = JsonMap<String, Json>;
-    // const DESTINATION_TAG: &str = "DestinationTag";
-    // const DESTINATION: &str = "Destination";
-    // const SOURCE_TAG: &str = "SourceTag";
-    // const ACCOUNT: &str = "Account";
-    //
-    // fn pre_process_x_addr(
-    //     tx_object: &TransactionJson,
-    //     pre_processed: &mut PreProcessedObject,
-    //     field: String,
-    //     addr: XAddress,
-    // ) -> SigningResult<()> {
-    //     let classic_addr = addr
-    //         .to_classic()
-    //         .into_tw()
-    //         .context("Error converting an XAddress to Classic")?
-    //         .to_string();
-    //
-    //     let tag = Json::Number(addr.destination_tag().into());
-    //     let tag_name = if field == DESTINATION {
-    //         DESTINATION_TAG
-    //     } else if field == ACCOUNT {
-    //         SOURCE_TAG
-    //     } else {
-    //         return SigningError::err(SigningErrorType::Error_invalid_address).context(format!(
-    //             "Field `{field}` is not allowed to have an associated tag."
-    //         ));
-    //     };
-    //
-    //     // Check whether the Transaction object contains the tag already.
-    //     // If so, it must be equal to the tag of a corresponding XAddress.
-    //     if let Some(handled_tag) = tx_object.get(tag_name) {
-    //         if handled_tag != &tag {
-    //             return SigningError::err(SigningErrorType::Error_invalid_params).context("Cannot have mismatched Account/Destination X-Address and SourceTag/DestinationTag");
-    //         }
-    //     }
-    //
-    //     pre_processed.insert(field, Json::String(classic_addr));
-    //     pre_processed.insert(tag_name.to_string(), tag);
-    //     Ok(())
-    // }
+    fn pre_process_x_addr(
+        tx_object: &TransactionJson,
+        pre_processed: &mut PreProcessedObject,
+        field: String,
+        addr: XAddress,
+    ) -> SigningResult<()> {
+        let classic_addr = addr
+            .to_classic()
+            .into_tw()
+            .context("Error converting an XAddress to Classic")?
+            .to_string();
+
+        let tag = Json::Number(addr.destination_tag().into());
+        let tag_name = if field == DESTINATION {
+            DESTINATION_TAG
+        } else if field == ACCOUNT {
+            SOURCE_TAG
+        } else {
+            return SigningError::err(SigningErrorType::Error_invalid_address).context(format!(
+                "Field `{field}` is not allowed to have an associated tag."
+            ));
+        };
+
+        // Check whether the Transaction object contains the tag already.
+        // If so, it must be equal to the tag of a corresponding XAddress.
+        if let Some(handled_tag) = tx_object.get(tag_name) {
+            if handled_tag != &tag {
+                return SigningError::err(SigningErrorType::Error_invalid_params).context("Cannot have mismatched Account/Destination X-Address and SourceTag/DestinationTag");
+            }
+        }
+
+        pre_processed.insert(field, Json::String(classic_addr));
+        pre_processed.insert(tag_name.to_string(), tag);
+        Ok(())
+    }
 }
@@ -14,7 +14,15 @@ use std::str::FromStr;
 use tw_coin_entry::error::prelude::*;
 use tw_hash::{Hash, H128, H160, H256};
 
-/// Only supported types.
+/// XRPL supported types.
+/// Missing types:
+/// * Issue
+/// * Path
+/// * PathSet
+/// * PathStep
+/// * STArray
+/// * STObject
+/// * XChainBridge
 pub enum XRPLTypes {
     AccountID(AccountId),
     Amount(Amount),
@@ -23,18 +31,11 @@ pub enum XRPLTypes {
     Hash128(H128),
     Hash160(H160),
     Hash256(H256),
-    // Issue(Issue),
-    // Path(Path),
-    // PathSet(PathSet),
-    // PathStep(PathStep),
     Vector256(H256),
-    // STArray(STArray),
-    // STObject(STObject),
     UInt8(u8),
     UInt16(u16),
     UInt32(u32),
     UInt64(u64),
-    // XChainBridge(XChainBridge),
 }
 
 impl XRPLTypes {

@@ -0,0 +1,256 @@
+[
+    {
+        "binary_no_signing": "120007220000000024000017B42A535A8CF164400000000608434065D48EEBE0B40E8000000000000000000000000000434E590000000000CED6E99370D5C00EF4EBF72567DA99F5661BFB3A68400000000000000C8114AD6E583D47F90F29FD8B23225E6F905602B0292E",
+        "json": {
+            "Account": "rGFpans8aW7XZNEcNky6RHKyEdLvXPMnUn",
+            "Expiration": 1398443249,
+            "Fee": "12",
+            "Flags": 0,
+            "Sequence": 6068,
+            "TakerGets": {
+                "currency": "CNY",
+                "issuer": "rKiCet8SdvWxPXnAgYarFUXMh1zCPz432Y",
+                "value": "4.2"
+            },
+            "TakerPays": "101204800",
+            "TransactionType": "OfferCreate"
+        }
+    },
+    {
+        "binary_no_signing": "12000722000000002400005124201B005EE8EC64400000000014025165D4122B7C477B075F000000000000000000000000434E590000000000AA8114C65DA8EA1BE40849F974685289CC145CCF68400000000000000C8114D0B32295596E50017E246FE85FC5982A1BD89CE4",
+        "json": {
+            "Account": "rLpW9Reyn9YqZ8mxbq8nviXSp4TnHafVJQ",
+            "Fee": "12",
+            "Flags": 0,
+            "LastLedgerSequence": 6220012,
+            "Sequence": 20772,
+            "TakerGets": {
+                "currency": "CNY",
+                "issuer": "rGYYWKxT1XgNipUJouCq4cKiyAdq8xBoE9",
+                "value": "0.05114362355976031"
+            },
+            "TakerPays": "1311313",
+            "TransactionType": "OfferCreate"
+        }
+    },
+    {
+        "binary_no_signing": "12000724000809172019000808DA64D4047BD23375F33500000000000000000000000042544300000000000A20B3C85F482532A9578DBB3950B85CA06594D165400000003C3945C26840000000000000328114F4141D8B4EF33BC3EE224088CA418DFCD2847193",
+        "json": {
+            "Account": "rPEZyTnSyQyXBCwMVYyaafSVPL8oMtfG6a",
+            "Fee": "50",
+            "OfferSequence": 526554,
+            "Sequence": 526615,
+            "TakerGets": "1010386370",
+            "TakerPays": {
+                "currency": "BTC",
+                "issuer": "rvYAfWj5gh67oV6fW32ZzP3Aw4Eubs59B",
+                "value": "0.01262042643559221"
+            },
+            "TransactionType": "OfferCreate"
+        }
+    },
+    {
+        "binary_no_signing": "120000228000000024000054C761D54416B0AE3B00000000000000000000000000005244440000000000387B5123A1C93417271BA6DBBBD087E68E7445B268400000000000000A69D54417BCE6C800000000000000000000000000005244440000000000387B5123A1C93417271BA6DBBBD087E68E7445B28114F7B414E9D25EE050553D8A0BB27202F4249AD3288314B83EB506BBE5BCF3E89C638FDB185B1DEAC96584",
+        "json": {
+            "Account": "rP2jdgJhtY1pwDJQEMLfCixesg4cw8HcrW",
+            "Amount": {
+                "currency": "RDD",
+                "issuer": "ra9eZxMbJrUcgV8ui7aPc161FgrqWScQxV",
+                "value": "1150.848"
+            },
+            "Destination": "rHoUTGMxWKbrTTF8tpAjysjpu8PWrbt1Wx",
+            "Fee": "10",
+            "Flags": 2147483648,
+            "SendMax": {
+                "currency": "RDD",
+                "issuer": "ra9eZxMbJrUcgV8ui7aPc161FgrqWScQxV",
+                "value": "1152"
+            },
+            "Sequence": 21703,
+            "TransactionType": "Payment"
+        }
+    },
+    {
+        "binary_no_signing": "120000220000000024000000026140000000017D784068400000000000000A81145CCB151F6E9D603F394AE778ACF10D3BECE874F68314E851BBBE79E328E43D68F43445368133DF5FBA5A",
+        "json": {
+            "Account": "r9TeThyi5xiuUUrFjtPKZiHcDxs7K9H6Rb",
+            "Amount": "25000000",
+            "Destination": "r4BPgS7DHebQiU31xWELvZawwSG2fSPJ7C",
+            "Fee": "10",
+            "Flags": 0,
+            "Sequence": 2,
+            "TransactionType": "Payment"
+        }
+    },
+    {
+        "binary_no_signing": "12000022000000002400000090201B005EE9BA614000000000030D4068400000000000000F8114AA1BD19D9E87BE8069FDBF6843653C43837C03C6831467FE6EC28E0464DD24FB2D62A492AAC697CFAD02",
+        "json": {
+            "Account": "rGWTUVmm1fB5QUjMYn8KfnyrFNgDiD9H9e",
+            "Amount": "200000",
+            "Destination": "rw71Qs1UYQrSQ9hSgRohqNNQcyjCCfffkQ",
+            "Fee": "15",
+            "Flags": 0,
+            "LastLedgerSequence": 6220218,
+            "Sequence": 144,
+            "TransactionType": "Payment"
+        }
+    },
+    {
+        "binary_no_signing": "120000220000000024000000012EF72D50CA6140000000017D784068400000000000000C8114E851BBBE79E328E43D68F43445368133DF5FBA5A831476DAC5E814CD4AA74142C3AB45E69A900E637AA2",
+        "json": {
+            "Account": "r4BPgS7DHebQiU31xWELvZawwSG2fSPJ7C",
+            "Amount": "25000000",
+            "Destination": "rBqSFEFg2B6GBMobtxnU1eLA1zbNC9NDGM",
+            "DestinationTag": 4146942154,
+            "Fee": "12",
+            "Flags": 0,
+            "Sequence": 1,
+            "TransactionType": "Payment"
+        }
+    },
+    {
+        "binary_no_signing": "12000023000A34F8240000888A61400000000007A120684000000000000014811408F41F116A1F60D60296B16907F0A041BF10619783146E2F0455C46CF5DF61A1E58419A89D45459045EA",
+        "json": {
+            "Account": "rFLiPGytDEwC5heoqFcFAZoqPPmKBzX1o",
+            "Amount": "500000",
+            "Destination": "rBsbetvMYuMkEeHZYizPMkpveCVH8EVQYd",
+            "Fee": "20",
+            "Sequence": 34954,
+            "SourceTag": 668920,
+            "TransactionType": "Payment"
+        }
+    },
+    {
+        "binary_no_signing": "1200082200000000240000512120190000511B201B005EE8E968400000000000000C8114D0B32295596E50017E246FE85FC5982A1BD89CE4",
+        "json": {
+            "Account": "rLpW9Reyn9YqZ8mxbq8nviXSp4TnHafVJQ",
+            "Fee": "12",
+            "Flags": 0,
+            "LastLedgerSequence": 6220009,
+            "OfferSequence": 20763,
+            "Sequence": 20769,
+            "TransactionType": "OfferCancel"
+        }
+    },
+    {
+        "binary_no_signing": "1200052280000000240000000368400000000000000A811448E143E2384A1B3C69A412789F2CA3FCE2F65F0B881448E143E2384A1B3C69A412789F2CA3FCE2F65F0B",
+        "json": {
+            "Account": "rfeMWWbSaGqc6Yth2dTetLBeKeUTTfE2pG",
+            "Fee": "10",
+            "Flags": 2147483648,
+            "RegularKey": "rfeMWWbSaGqc6Yth2dTetLBeKeUTTfE2pG",
+            "Sequence": 3,
+            "TransactionType": "SetRegularKey"
+        }
+    },
+    {
+        "binary_no_signing": "120005228000000024000000EE201B005EF94C68400000000000000C8114CB3F392892D0772FF5AD155D8D70404B1DB2ACFE8814F2F9A54D9CEBBE64342B52DE3450FFA0738C8D00",
+        "json": {
+            "Account": "rKXCummUHnenhYudNb9UoJ4mGBR75vFcgz",
+            "Fee": "12",
+            "Flags": 2147483648,
+            "LastLedgerSequence": 6224204,
+            "RegularKey": "rP9jbfTepHAHWB4q9YjNkLyaZT15uvexiZ",
+            "Sequence": 238,
+            "TransactionType": "SetRegularKey"
+        }
+    },
+    {
+        "binary_no_signing": "1200142200020000240000002C63D6438D7EA4C680000000000000000000000000005743470000000000832297BEF589D59F9C03A84F920F8D9128CC1CE468400000000000000C8114BE6C30732AE33CF2AF3344CE8172A6B9300183E3",
+        "json": {
+            "Account": "rJMiz2rCMjZzEMijXNH1exNBryTQEjFd9S",
+            "Fee": "12",
+            "Flags": 131072,
+            "LimitAmount": {
+                "currency": "WCG",
+                "issuer": "rUx4xgE7bNWCCgGcXv1CCoQyTcCeZ275YG",
+                "value": "10000000"
+            },
+            "Sequence": 44,
+            "TransactionType": "TrustSet"
+        }
+    },
+    {
+        "binary_no_signing": "1200142280020000240000002B201B005EEAAF63D4838D7EA4C680000000000000000000000000004254430000000000DD39C650A96EDA48334E70CC4A85B8B2E8502CD368400000000000000C81148353C031DF5AA061A23535E6ABCEEEA23F152B1E",
+        "json": {
+            "Account": "rUyPiNcSFFj6uMR2gEaD8jUerQ59G1qvwN",
+            "Fee": "12",
+            "Flags": 2147614720,
+            "LastLedgerSequence": 6220463,
+            "LimitAmount": {
+                "currency": "BTC",
+                "issuer": "rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q",
+                "value": "1"
+            },
+            "Sequence": 43,
+            "TransactionType": "TrustSet"
+        }
+    },
+    {
+        "binary_no_signing": "1200032200000000240000296668400000000000000A81140F3D0C7D2CFAB2EC8295451F0B3CA038E8E9CDCD",
+        "json": {
+            "Account": "rpP2GdsQwenNnFPefbXFgiTvEgJWQpq8Rw",
+            "Fee": "10",
+            "Flags": 0,
+            "Sequence": 10598,
+            "TransactionType": "AccountSet"
+        }
+    },
+    {
+        "binary_no_signing": "12000322000000002400000122201B005EECD668400000000000000F8114ABBD4A3AF95FDFD6D072F11421D8F107CAEA1852",
+        "json": {
+            "Account": "rGCnJuD31Kx4QGZJ2dX7xoje6T4Zr5s9EB",
+            "Fee": "15",
+            "Flags": 0,
+            "LastLedgerSequence": 6221014,
+            "Sequence": 290,
+            "TransactionType": "AccountSet"
+        }
+    },
+    {
+        "description": "Destination and Source are XAddress",
+        "binary_no_signing": "12000022000000002300014B76240000003E2E000003F26140000002540BE40068400000000000000A7321034AADB09CFF4A4804073701EC53C3510CDC95917C2BB0150FB742D0C66E6CEE9E74473045022022EB32AECEF7C644C891C19F87966DF9C62B1F34BABA6BE774325E4BB8E2DD62022100A51437898C28C2B297112DF8131F2BB39EA5FE613487DDD611525F17962646398114550FC62003E785DC231A1058A05E56E3F09CF4E68314D4CC8AB5B21D86A82C3E9E8D0ECF2404B77FECBA",
+        "json": {
+            "Account": "X7tFPvjMH7nDxP8nTGkeeggcUpCZj8UbyT2QoiRHGDfjqrB",
+            "Destination": "XVYmGpJqHS95ir411XvanwY1xt5Z2314WsamHPVgUNABUGV",
+            "TransactionType": "Payment",
+            "TxnSignature": "3045022022EB32AECEF7C644C891C19F87966DF9C62B1F34BABA6BE774325E4BB8E2DD62022100A51437898C28C2B297112DF8131F2BB39EA5FE613487DDD611525F1796264639",
+            "SigningPubKey": "034AADB09CFF4A4804073701EC53C3510CDC95917C2BB0150FB742D0C66E6CEE9E",
+            "Amount": "10000000000",
+            "Fee": "10",
+            "Flags": 0,
+            "Sequence": 62
+        }
+    },
+    {
+        "description": "Destination is XAddress, Source is classic, however SourceTag is specified",
+        "binary_no_signing": "1200002280000000233BA47B242403528A932E3BA47B24614000000059682F00684000000000001388732102ECB814477DF9D8351918878E235EE6AF147A2A5C20F1E71F291F0F3303357C367446304402202A90972E21823214733082E1977F9EA2D6B5101902F108E7BDD7D128CEEA7AF3022008852C8DAD746A7F18E66A47414FABF551493674783E8EA7409C501D3F05F99A811418E58D55BA0A0D22DEF988C22D6271CEBB5D2B1C83148E0D713E837D8C34420B42F2CE1698BDFFB27FA5",
+        "json": {
+            "Account": "rsGeDwS4rpocUumu9smpXomzaaeG4Qyifz",
+            "Amount": "1500000000",
+            "Destination": "XVBkK1yLutMqFGwTm6hykn7YXGDUrjsZSkpzMgRveZrMbHs",
+            "Fee": "5000",
+            "Flags": 2147483648,
+            "Sequence": 55741075,
+            "SigningPubKey": "02ECB814477DF9D8351918878E235EE6AF147A2A5C20F1E71F291F0F3303357C36",
+            "SourceTag": 1000635172,
+            "TransactionType": "Payment",
+            "TxnSignature": "304402202A90972E21823214733082E1977F9EA2D6B5101902F108E7BDD7D128CEEA7AF3022008852C8DAD746A7F18E66A47414FABF551493674783E8EA7409C501D3F05F99A"
+        }
+    },
+    {
+        "description": "Destination is XAddress, Source is classic, no tags provided",
+        "binary_no_signing": "12000022800000002400007F812E0650D1EA614000000B63C512A068400000000000000A732102E98DA545CCCC5D14C82594EE9E6CCFCF5171108E2410B3E784183E1068D334297447304502210091DCA7AF189CD9DC93BDE24DEAE87381FBF16789C43113EE312241D648982B2402201C6055FEFFF1F119640AAC0B32C4F37375B0A96033E0527A21C1366920D6A5248114B51C0DAC2EF22C5CD6FBCFA1E7778D20922D61E48314A025D8B3210251C94FA3AAC92E159673A140FAD9",
+        "json": {
+            "Account": "rHWcuuZoFvDS6gNbmHSdpb7u1hZzxvCoMt",
+            "Amount": "48918500000",
+            "Destination": "XVH3aqvbYGhRhrD1FYSzGooNuxdzbG3VR2fuM47oqbXxQr7",
+            "Fee": "10",
+            "Flags": 2147483648,
+            "Sequence": 32641,
+            "SigningPubKey": "02E98DA545CCCC5D14C82594EE9E6CCFCF5171108E2410B3E784183E1068D33429",
+            "TransactionType": "Payment",
+            "TxnSignature": "304502210091DCA7AF189CD9DC93BDE24DEAE87381FBF16789C43113EE312241D648982B2402201C6055FEFFF1F119640AAC0B32C4F37375B0A96033E0527A21C1366920D6A524"
+        }
+    }
+]
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: Apache-2.0
+//
+// Copyright © 2017 Trust Wallet.
+
+use serde_json::Value as Json;
+use tw_encoding::hex::ToHex;
+use tw_ripple::encode::st_object::STObject;
+
+const TRANSACTION_CASES: &str = include_str!("data/transactions.json");
+
+#[test]
+fn test_encode_json_transaction() {
+    let input: Json = serde_json::from_str(TRANSACTION_CASES).unwrap();
+
+    for (idx, test) in input.as_array().unwrap().iter().enumerate() {
+        let tx_json = &test["json"];
+        let binary_no_signing = test["binary_no_signing"].as_str().unwrap();
+
+        let signing_only = false;
+        let serialized = STObject::try_from_value(tx_json.clone(), signing_only)
+            .expect(&format!("Error encoding transaction[{idx}]: {tx_json:?}"));
+
+        assert_eq!(serialized.0.to_hex().to_uppercase(), binary_no_signing);
+    }
+}
@@ -44,6 +44,71 @@ macro_rules! deserialize_from_str {
     };
 }
 
+pub mod hashmap_as_tupple_list {
+    use serde::de::{SeqAccess, Visitor};
+    use serde::ser::SerializeSeq;
+    use serde::{Deserialize, Deserializer, Serialize, Serializer};
+    use std::collections::HashMap;
+    use std::fmt;
+    use std::hash::Hash;
+
+    pub fn serialize<K, V, S>(map: &HashMap<K, V>, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        K: Serialize,
+        V: Serialize,
+        S: Serializer,
+    {
+        let mut seq = serializer.serialize_seq(Some(map.len()))?;
+        for (k, v) in map {
+            seq.serialize_element(&(k, v))?;
+        }
+        seq.end()
+    }
+
+    /// Deserialize a value from a string.
+    pub fn deserialize<'de, D, K, V>(deserializer: D) -> Result<HashMap<K, V>, D::Error>
+    where
+        D: Deserializer<'de>,
+        K: Deserialize<'de> + Eq + Hash,
+        V: Deserialize<'de>,
+    {
+        struct MapVisitor<K, V> {
+            marker: std::marker::PhantomData<fn() -> HashMap<K, V>>,
+        }
+
+        impl<'de, K, V> Visitor<'de> for MapVisitor<K, V>
+        where
+            K: Deserialize<'de> + Eq + Hash,
+            V: Deserialize<'de>,
+        {
+            type Value = HashMap<K, V>;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("a sequence of key-value pairs")
+            }
+
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+            where
+                A: SeqAccess<'de>,
+            {
+                let mut map = match seq.size_hint() {
+                    Some(capacity) => HashMap::with_capacity(capacity),
+                    None => HashMap::new(),
+                };
+                while let Some((k, v)) = seq.next_element()? {
+                    map.insert(k, v);
+                }
+
+                Ok(map)
+            }
+        }
+
+        deserializer.deserialize_seq(MapVisitor {
+            marker: std::marker::PhantomData,
+        })
+    }
+}
+
 pub mod as_string {
     use serde::de::Error as DeError;
     use serde::{Deserialize, Deserializer, Serialize, Serializer};