embed jsonrpc types from jsonrpc-core crate (#2801)

We should not depend on jsonrpc-core anymore:

* The project just announced it's no longer actively maintained[^1],
  preferring their new implementation in `jsonrpsee`.
* The types are too strict: we would benefit from removing some
  `#[serde(deny_unknown_fields)]` annotations to allow language
  servers that disrespect the spec[^2].
* We don't use much of the project. Just the types out of core.
  These are easy to embed directly into the `helix-lsp` crate.

[^1]: https://github.com/paritytech/jsonrpc/pull/674
[^2]: https://github.com/helix-editor/helix/issues/2786

5 files changed, 373 insertions, 5 deletions

diff --git a/helix-lsp/Cargo.toml b/helix-lsp/Cargo.toml
index fb36758f..b7d26662 100644
--- a/helix-lsp/Cargo.toml
+++ b/helix-lsp/Cargo.toml
@@ -17,7 +17,6 @@ helix-core = { version = "0.6", path = "../helix-core" }
 anyhow = "1.0"
 futures-executor = "0.3"
 futures-util = { version = "0.3", features = ["std", "async-await"], default-features = false }
-jsonrpc-core = { version = "18.0", default-features = false } # don't pull in all of futures
 log = "0.4"
 lsp-types = { version = "0.93", features = ["proposed"] }
 serde = { version = "1.0", features = ["derive"] }
diff --git a/helix-lsp/src/client.rs b/helix-lsp/src/client.rs
index 7f556ca6..8ee9c9d7 100644
--- a/helix-lsp/src/client.rs
+++ b/helix-lsp/src/client.rs
@@ -1,11 +1,11 @@
 use crate::{
+    jsonrpc,
     transport::{Payload, Transport},
     Call, Error, OffsetEncoding, Result,
 };
 
 use anyhow::anyhow;
 use helix_core::{find_root, ChangeSet, Rope};
-use jsonrpc_core as jsonrpc;
 use lsp_types as lsp;
 use serde::Deserialize;
 use serde_json::Value;
diff --git a/helix-lsp/src/jsonrpc.rs b/helix-lsp/src/jsonrpc.rs
new file mode 100644
index 00000000..b9b3fd2c
--- /dev/null
+++ b/helix-lsp/src/jsonrpc.rs
@@ -0,0 +1,370 @@
+//! An implementation of the JSONRPC 2.0 spec types
+
+// Upstream implementation: https://github.com/paritytech/jsonrpc/tree/38af3c9439aa75481805edf6c05c6622a5ab1e70/core/src/types
+// Changes from upstream:
+// * unused functions (almost all non-trait-implementation functions) have been removed
+// * `#[serde(deny_unknown_fields)]` annotations have been removed on response types
+//   for compatibility with non-strict language server implementations like Ruby Sorbet
+//   (see https://github.com/helix-editor/helix/issues/2786)
+// * some variable names have been lengthened for readability
+
+use serde::de::{self, DeserializeOwned, Visitor};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+// https://www.jsonrpc.org/specification#error_object
+#[derive(Debug, PartialEq, Clone)]
+pub enum ErrorCode {
+    ParseError,
+    InvalidRequest,
+    MethodNotFound,
+    InvalidParams,
+    InternalError,
+    ServerError(i64),
+}
+
+impl ErrorCode {
+    pub fn code(&self) -> i64 {
+        match *self {
+            ErrorCode::ParseError => -32700,
+            ErrorCode::InvalidRequest => -32600,
+            ErrorCode::MethodNotFound => -32601,
+            ErrorCode::InvalidParams => -32602,
+            ErrorCode::InternalError => -32603,
+            ErrorCode::ServerError(code) => code,
+        }
+    }
+}
+
+impl From<i64> for ErrorCode {
+    fn from(code: i64) -> Self {
+        match code {
+            -32700 => ErrorCode::ParseError,
+            -32600 => ErrorCode::InvalidRequest,
+            -32601 => ErrorCode::MethodNotFound,
+            -32602 => ErrorCode::InvalidParams,
+            -32603 => ErrorCode::InternalError,
+            code => ErrorCode::ServerError(code),
+        }
+    }
+}
+
+impl<'de> Deserialize<'de> for ErrorCode {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let code: i64 = Deserialize::deserialize(deserializer)?;
+        Ok(ErrorCode::from(code))
+    }
+}
+
+impl Serialize for ErrorCode {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        serializer.serialize_i64(self.code())
+    }
+}
+
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
+pub struct Error {
+    pub code: ErrorCode,
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data: Option<Value>,
+}
+
+impl Error {
+    pub fn invalid_params<M>(message: M) -> Self
+    where
+        M: Into<String>,
+    {
+        Error {
+            code: ErrorCode::InvalidParams,
+            message: message.into(),
+            data: None,
+        }
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{:?}: {}", self.code, self.message)
+    }
+}
+
+impl std::error::Error for Error {}
+
+// https://www.jsonrpc.org/specification#request_object
+
+/// Request ID
+#[derive(Debug, PartialEq, Clone, Hash, Eq, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum Id {
+    Null,
+    Num(u64),
+    Str(String),
+}
+
+/// Protocol Version
+#[derive(Debug, PartialEq, Clone, Copy, Hash, Eq)]
+pub enum Version {
+    V2,
+}
+
+impl Serialize for Version {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        match *self {
+            Version::V2 => serializer.serialize_str("2.0"),
+        }
+    }
+}
+
+struct VersionVisitor;
+
+impl<'v> Visitor<'v> for VersionVisitor {
+    type Value = Version;
+
+    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+        formatter.write_str("a string")
+    }
+    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+    where
+        E: de::Error,
+    {
+        match value {
+            "2.0" => Ok(Version::V2),
+            _ => Err(de::Error::custom("invalid version")),
+        }
+    }
+}
+
+impl<'de> Deserialize<'de> for Version {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        deserializer.deserialize_identifier(VersionVisitor)
+    }
+}
+
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum Params {
+    None,
+    Array(Vec<Value>),
+    Map(serde_json::Map<String, Value>),
+}
+
+impl Params {
+    pub fn parse<D>(self) -> Result<D, Error>
+    where
+        D: DeserializeOwned,
+    {
+        let value: Value = self.into();
+        serde_json::from_value(value)
+            .map_err(|err| Error::invalid_params(format!("Invalid params: {}.", err)))
+    }
+}
+
+impl From<Params> for Value {
+    fn from(params: Params) -> Value {
+        match params {
+            Params::Array(vec) => Value::Array(vec),
+            Params::Map(map) => Value::Object(map),
+            Params::None => Value::Null,
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct MethodCall {
+    pub jsonrpc: Option<Version>,
+    pub method: String,
+    #[serde(default = "default_params")]
+    pub params: Params,
+    pub id: Id,
+}
+
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct Notification {
+    pub jsonrpc: Option<Version>,
+    pub method: String,
+    #[serde(default = "default_params")]
+    pub params: Params,
+}
+
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+#[serde(untagged)]
+pub enum Call {
+    MethodCall(MethodCall),
+    Notification(Notification),
+    Invalid {
+        // We can attempt to salvage the id out of the invalid request
+        // for better debugging
+        #[serde(default = "default_id")]
+        id: Id,
+    },
+}
+
+fn default_params() -> Params {
+    Params::None
+}
+
+fn default_id() -> Id {
+    Id::Null
+}
+
+impl From<MethodCall> for Call {
+    fn from(method_call: MethodCall) -> Self {
+        Call::MethodCall(method_call)
+    }
+}
+
+impl From<Notification> for Call {
+    fn from(notification: Notification) -> Self {
+        Call::Notification(notification)
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+#[serde(untagged)]
+pub enum Request {
+    Single(Call),
+    Batch(Vec<Call>),
+}
+
+// https://www.jsonrpc.org/specification#response_object
+
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
+pub struct Success {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub jsonrpc: Option<Version>,
+    pub result: Value,
+    pub id: Id,
+}
+
+#[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
+pub struct Failure {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub jsonrpc: Option<Version>,
+    pub error: Error,
+    pub id: Id,
+}
+
+// Note that failure comes first because we're not using
+// #[serde(deny_unknown_field)]: we want a request that contains
+// both `result` and `error` to be a `Failure`.
+#[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum Output {
+    Failure(Failure),
+    Success(Success),
+}
+
+impl From<Output> for Result<Value, Error> {
+    fn from(output: Output) -> Self {
+        match output {
+            Output::Success(success) => Ok(success.result),
+            Output::Failure(failure) => Err(failure.error),
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum Response {
+    Single(Output),
+    Batch(Vec<Output>),
+}
+
+impl From<Failure> for Response {
+    fn from(failure: Failure) -> Self {
+        Response::Single(Output::Failure(failure))
+    }
+}
+
+impl From<Success> for Response {
+    fn from(success: Success) -> Self {
+        Response::Single(Output::Success(success))
+    }
+}
+
+#[test]
+fn method_call_serialize() {
+    use serde_json;
+
+    let m = MethodCall {
+        jsonrpc: Some(Version::V2),
+        method: "update".to_owned(),
+        params: Params::Array(vec![Value::from(1), Value::from(2)]),
+        id: Id::Num(1),
+    };
+
+    let serialized = serde_json::to_string(&m).unwrap();
+    assert_eq!(
+        serialized,
+        r#"{"jsonrpc":"2.0","method":"update","params":[1,2],"id":1}"#
+    );
+}
+
+#[test]
+fn notification_serialize() {
+    use serde_json;
+
+    let n = Notification {
+        jsonrpc: Some(Version::V2),
+        method: "update".to_owned(),
+        params: Params::Array(vec![Value::from(1), Value::from(2)]),
+    };
+
+    let serialized = serde_json::to_string(&n).unwrap();
+    assert_eq!(
+        serialized,
+        r#"{"jsonrpc":"2.0","method":"update","params":[1,2]}"#
+    );
+}
+
+#[test]
+fn success_output_deserialize() {
+    use serde_json;
+
+    let dso = r#"{"jsonrpc":"2.0","result":1,"id":1}"#;
+
+    let deserialized: Output = serde_json::from_str(dso).unwrap();
+    assert_eq!(
+        deserialized,
+        Output::Success(Success {
+            jsonrpc: Some(Version::V2),
+            result: Value::from(1),
+            id: Id::Num(1)
+        })
+    );
+}
+
+#[test]
+fn success_output_deserialize_with_extra_fields() {
+    use serde_json;
+
+    // https://github.com/helix-editor/helix/issues/2786
+    let dso = r#"{"jsonrpc":"2.0","result":1,"id":1,"requestMethod":"initialize"}"#;
+
+    let deserialized: Output = serde_json::from_str(dso).unwrap();
+    assert_eq!(
+        deserialized,
+        Output::Success(Success {
+            jsonrpc: Some(Version::V2),
+            result: Value::from(1),
+            id: Id::Num(1)
+        })
+    );
+}
diff --git a/helix-lsp/src/lib.rs b/helix-lsp/src/lib.rs
index 2bc554e6..6a5f9d5c 100644
--- a/helix-lsp/src/lib.rs
+++ b/helix-lsp/src/lib.rs
@@ -1,10 +1,10 @@
 mod client;
+pub mod jsonrpc;
 mod transport;
 
 pub use client::Client;
 pub use futures_executor::block_on;
 pub use jsonrpc::Call;
-pub use jsonrpc_core as jsonrpc;
 pub use lsp::{Position, Url};
 pub use lsp_types as lsp;
 
diff --git a/helix-lsp/src/transport.rs b/helix-lsp/src/transport.rs
index 6102c6c8..8aaeae3d 100644
--- a/helix-lsp/src/transport.rs
+++ b/helix-lsp/src/transport.rs
@@ -1,6 +1,5 @@
-use crate::{Error, Result};
+use crate::{jsonrpc, Error, Result};
 use anyhow::Context;
-use jsonrpc_core as jsonrpc;
 use log::{error, info};
 use serde::{Deserialize, Serialize};
 use serde_json::Value;