Create a type-safe configuration library

Cargo.lock

@@ -74,15 +74,6 @@ version = "0.21.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "604178f6c5c21f02dc555784810edfb88d34ac2c73b2eae109655649ee73ce3d"
 
-[[package]]
-name = "basic-toml"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7bfc506e7a2370ec239e1d072507b2a80c833083699d3c6fa176fbb4de8448c6"
-dependencies = [
- "serde",
-]
-
 [[package]]
 name = "bit-set"
 version = "0.5.3"
@@ -246,13 +237,19 @@ checksum = "3d7b894f5411737b7867f4827955924d7c254fc9f4d91a6aad6b097804b1018b"
 name = "config"
 version = "0.1.0"
 dependencies = [
+ "config-derive",
  "cool_asserts",
- "quote",
  "serde",
  "serde_json",
- "syn 1.0.109",
  "thiserror",
- "trybuild",
+]
+
+[[package]]
+name = "config-derive"
+version = "0.1.0"
+dependencies = [
+ "quote",
+ "syn 1.0.109",
 ]
 
 [[package]]
@@ -407,12 +404,6 @@ dependencies = [
  "syn 2.0.28",
 ]
 
-[[package]]
-name = "dissimilar"
-version = "1.0.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86e3bdc80eee6e16b2b6b0f87fbc98c04bee3455e35174c0de1a125d0688c632"
-
 [[package]]
 name = "either"
 version = "1.9.0"
@@ -903,12 +894,6 @@ dependencies = [
  "system-deps",
 ]
 
-[[package]]
-name = "glob"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
-
 [[package]]
 name = "gobject-sys"
 version = "0.17.10"
@@ -2257,15 +2242,6 @@ dependencies = [
  "windows-sys",
 ]
 
-[[package]]
-name = "termcolor"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "be55cf8942feac5c765c2c993422806843c9a9a45d4d5c407ad6dd2ea95eb9b6"
-dependencies = [
- "winapi-util",
-]
-
 [[package]]
 name = "thiserror"
 version = "1.0.46"
@@ -2452,22 +2428,6 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3528ecfd12c466c6f163363caf2d02a71161dd5e1cc6ae7b34207ea2d42d81ed"
 
-[[package]]
-name = "trybuild"
-version = "1.0.82"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a84e0202ea606ba5ebee8507ab2bfbe89b98551ed9b8f0be198109275cff284b"
-dependencies = [
- "basic-toml",
- "dissimilar",
- "glob",
- "once_cell",
- "serde",
- "serde_derive",
- "serde_json",
- "termcolor",
-]
-
 [[package]]
 name = "type-map"
 version = "0.4.0"
@@ -2726,15 +2686,6 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 
-[[package]]
-name = "winapi-util"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
-dependencies = [
- "winapi",
-]
-
 [[package]]
 name = "winapi-x86_64-pc-windows-gnu"
 version = "0.4.0"

Cargo.toml

@@ -2,6 +2,7 @@
 members = [
     "changeset",
     "config",
+    "config-derive",
     "coordinates",
     "cyberpunk-splash",
     "dashboard",

build.sh

@@ -5,6 +5,7 @@ set -euo pipefail
 RUST_ALL_TARGETS=(
     "changeset"
     "config"
+    "config-derive"
     "coordinates"
     "cyberpunk-splash"
     "dashboard"

config-derive/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "config-derive"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lib]
+proc-macro = true
+
+[dependencies]
+quote           = { version = "1" }
+syn             = { version = "1", features = [ "extra-traits" ] }
+

config-derive/src/lib.rs

@@ -0,0 +1,23 @@
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+
+use syn::{parse_macro_input, DeriveInput};
+
+#[proc_macro_derive(ConfigOption)]
+pub fn derive(input: TokenStream) -> TokenStream {
+    let DeriveInput { ident, .. } = parse_macro_input!(input as DeriveInput);
+
+    let result = quote! {
+        impl From<&Config> for Option<#ident> {
+            fn from(config: &Config) -> Self {
+                match config.values.get(&ConfigName::#ident) {
+                    Some(ConfigOption::#ident(val)) => Some(val.clone()),
+                    _ => None,
+                }
+            }
+        }
+    };
+    result.into()
+}

config/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "config"
+version = "0.1.0"
+edition = "2021"
+
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+config-derive   = { path = "../config-derive" }
+serde_json      = { version = "1" }
+serde           = { version = "1", features = [ "derive" ] }
+thiserror       = { version = "1" }
+
+[dev-dependencies]
+cool_asserts    = { version = "2" }

config/src/lib.rs

@@ -0,0 +1,154 @@
+pub use config_derive::ConfigOption;
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum ConfigReadError {
+    #[error("Cannot read the configuration file: {0}")]
+    CannotRead(std::io::Error),
+    #[error("Cannot open the configuration file for reading: {0}")]
+    CannotOpen(std::io::Error),
+    #[error("Invalid json data found in the configurationfile: {0}")]
+    InvalidJSON(serde_json::Error),
+}
+
+macro_rules! define_config {
+    ($($name:ident($struct:ident),)+) => (
+        use serde::{Deserialize, Serialize};
+        use std::{
+            collections::HashMap,
+            fs::File,
+            hash::Hash,
+            io::{ErrorKind, Read},
+            path::PathBuf,
+        };
+
+        #[derive(Clone, Debug, Hash, PartialEq, Eq, Serialize, Deserialize)]
+        pub enum ConfigName {
+            $($name),+
+        }
+
+        #[derive(Clone, Debug, Serialize, Deserialize)]
+        pub enum ConfigOption {
+            $($name($struct)),+
+        }
+
+        #[derive(Clone, Debug)]
+        pub struct Config {
+            values: HashMap<ConfigName, ConfigOption>,
+        }
+
+        impl Config {
+            pub fn new() -> Self {
+                Self {
+                    values: HashMap::new(),
+                }
+            }
+
+            pub fn from_path(config_path: PathBuf) -> Result<Self, ConfigReadError> {
+                let mut settings = config_path.clone();
+                settings.push("config");
+
+                match File::open(settings) {
+                    Ok(mut file) => {
+                        let mut buf = String::new();
+                        file.read_to_string(&mut buf)
+                            .map_err(|err| ConfigReadError::CannotRead(err))?;
+                        let values = serde_json::from_str(buf.as_ref())
+                            .map_err(|err| ConfigReadError::InvalidJSON(err))?;
+                        Ok(Self {
+                            values,
+                        })
+                    }
+                    Err(io_err) => {
+                        match io_err.kind() {
+                            ErrorKind::NotFound => {
+                                /* create the path and an empty file */
+                                Ok(Self {
+                                    values: HashMap::new(),
+                                })
+                            }
+                            _ => Err(ConfigReadError::CannotOpen(io_err)),
+                        }
+                    }
+                }
+            }
+
+            pub fn set(&mut self, val: ConfigOption) {
+                let _ = match val {
+                    $(ConfigOption::$struct(_) => self.values.insert(ConfigName::$name, val)),+
+                };
+            }
+
+            pub fn get<'a, T>(&'a self) -> Option<T>
+            where
+                Option<T>: From<&'a Self>,
+            {
+                self.into()
+            }
+        }
+    )
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use cool_asserts::assert_matches;
+
+    define_config! {
+        DatabasePath(DatabasePath),
+        Me(Me),
+    }
+
+    #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, ConfigOption)]
+    pub struct DatabasePath(PathBuf);
+
+    #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+    enum Rank {
+        Kyu(i8),
+        Dan(i8),
+    }
+
+    #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, ConfigOption)]
+    pub struct Me {
+        name: String,
+        rank: Option<Rank>,
+    }
+
+    #[test]
+    fn it_can_set_and_get_options() {
+        let mut config: Config = Config::new();
+        config.set(ConfigOption::DatabasePath(DatabasePath(PathBuf::from(
+            "./fixtures/five_games",
+        ))));
+
+        assert_eq!(
+            Some(DatabasePath(PathBuf::from("./fixtures/five_games"))),
+            config.get()
+        );
+    }
+
+    #[test]
+    fn it_can_serialize_and_deserialize() {
+        let mut config = Config::new();
+        config.set(ConfigOption::DatabasePath(DatabasePath(PathBuf::from(
+            "fixtures/five_games",
+        ))));
+        config.set(ConfigOption::Me(Me {
+            name: "Savanni".to_owned(),
+            rank: Some(Rank::Kyu(10)),
+        }));
+        let s = serde_json::to_string(&config.values).unwrap();
+        println!("{}", s);
+        let values: HashMap<ConfigName, ConfigOption> = serde_json::from_str(s.as_ref()).unwrap();
+        println!("options: {:?}", values);
+
+        assert_matches!(values.get(&ConfigName::DatabasePath),
+                        Some(ConfigOption::DatabasePath(ref db_path)) =>
+                        assert_eq!(Some(db_path.clone()), config.get())
+        );
+
+        assert_matches!(values.get(&ConfigName::Me), Some(ConfigOption::Me(val)) =>
+            assert_eq!(Some(val.clone()), config.get())
+        );
+    }
+}