Codegen enums from IANA registries

crates/iana-codegen/src/traits.rs

@@ -0,0 +1,74 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use anyhow::Context;
+use async_trait::async_trait;
+use convert_case::{Case, Casing};
+use reqwest::Client;
+use serde::de::DeserializeOwned;
+
+#[derive(Debug)]
+pub struct EnumMember {
+    pub value: String,
+    pub description: Option<String>,
+    pub enum_name: String,
+}
+
+#[async_trait]
+pub trait EnumEntry: DeserializeOwned + Send + Sync {
+    const URL: &'static str;
+    const SECTIONS: &'static [&'static str];
+
+    fn key(&self) -> Option<&'static str>;
+    fn name(&self) -> &str;
+    fn description(&self) -> Option<&str> {
+        None
+    }
+    fn enum_name(&self) -> String {
+        self.name().replace('+', "_").to_case(Case::Pascal)
+    }
+
+    async fn fetch(client: &Client) -> anyhow::Result<Vec<(&'static str, EnumMember)>> {
+        tracing::info!("Fetching CSV");
+        let body = client
+            .get(Self::URL)
+            .send()
+            .await
+            .context(format!("can't the CSV at {}", Self::URL))?
+            .bytes()
+            .await
+            .context(format!("can't the CSV body at {}", Self::URL))?;
+
+        let parsed: Result<Vec<_>, _> = csv::Reader::from_reader(body.as_ref())
+            .into_deserialize()
+            .filter_map(|item: Result<Self, _>| {
+                item.map(|item| {
+                    item.key().map(|key| {
+                        (
+                            key,
+                            EnumMember {
+                                value: item.name().to_string(),
+                                description: item.description().map(ToString::to_string),
+                                enum_name: item.enum_name(),
+                            },
+                        )
+                    })
+                })
+                .transpose()
+            })
+            .collect();
+
+        Ok(parsed.context(format!("can't parse the CSV at {}", Self::URL))?)
+    }
+}