feat: json5 source support

Author: tenuous-guidance

confik/Cargo.toml

@@ -26,6 +26,7 @@ default = ["env", "toml"]
 # Source types
 env = ["dep:envious"]
 json = ["dep:serde_json"]
+json5 = ["dep:json5"]
 toml = ["dep:toml"]
 
 # Destination types
@@ -48,6 +49,7 @@ serde = { version = "1", default-features = false, features = ["std", "derive"]
 thiserror = "1"
 
 envious = { version = "0.2", optional = true }
+json5 = { version = "0.4", optional = true }
 serde_json = { version = "1", optional = true }
 toml = { version = "0.8", optional = true, default-features = false, features = ["parse"] }
 

confik/src/lib.rs

@@ -36,6 +36,8 @@ mod third_party;
 
 #[cfg(feature = "env")]
 pub use self::sources::env_source::EnvSource;
+#[cfg(feature = "json5")]
+pub use self::sources::json5_source::Json5Source;
 #[cfg(feature = "json")]
 pub use self::sources::json_source::JsonSource;
 #[cfg(feature = "toml")]

confik/src/sources/json5_source.rs

@@ -0,0 +1,94 @@
+use std::{borrow::Cow, error::Error, fmt};
+
+use crate::{ConfigurationBuilder, Source};
+
+/// A [`Source`] containing raw JSON data.
+#[derive(Clone)]
+pub struct Json5Source<'a> {
+    contents: Cow<'a, str>,
+    allow_secrets: bool,
+}
+
+impl<'a> Json5Source<'a> {
+    /// Creates a [`Source`] containing raw JSON data.
+    pub fn new(contents: impl Into<Cow<'a, str>>) -> Self {
+        Self {
+            contents: contents.into(),
+            allow_secrets: false,
+        }
+    }
+
+    /// Allows this source to contain secrets.
+    pub fn allow_secrets(mut self) -> Self {
+        self.allow_secrets = true;
+        self
+    }
+}
+
+impl<'a> Source for Json5Source<'a> {
+    fn allows_secrets(&self) -> bool {
+        self.allow_secrets
+    }
+
+    fn provide<T: ConfigurationBuilder>(&self) -> Result<T, Box<dyn Error + Sync + Send>> {
+        Ok(json5::from_str(&self.contents)?)
+    }
+}
+
+impl<'a> fmt::Debug for Json5Source<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Json5Source")
+            .field("allow_secrets", &self.allow_secrets)
+            .finish_non_exhaustive()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Configuration;
+
+    use super::*;
+
+    #[test]
+    fn defaults() {
+        let source = Json5Source::new("{}");
+        assert!(!source.allows_secrets());
+    }
+
+    #[test]
+    fn clone() {
+        let source = Json5Source::new("{}").allow_secrets();
+        assert!(source.allows_secrets());
+        assert!(source.clone().allow_secrets);
+    }
+
+    #[test]
+    fn json5() {
+        #[derive(Configuration, Debug, PartialEq)]
+        struct Config {
+            message: String,
+            n: i32,
+        }
+
+        let config = "
+            {
+              // A traditional message.
+              message: 'hello world',
+
+              // A number for some reason.
+              n: 42,
+            }
+        ";
+
+        assert_eq!(
+            Config::builder()
+                .override_with(Json5Source::new(config))
+                .try_build()
+                .expect("Failed to build config"),
+            Config {
+                message: "hello world".to_string(),
+                n: 42,
+            },
+        );
+    }
+}

confik/src/sources/mod.rs

@@ -56,6 +56,9 @@ pub(crate) mod file_source;
 #[cfg(feature = "toml")]
 pub(crate) mod toml_source;
 
+#[cfg(feature = "json5")]
+pub(crate) mod json5_source;
+
 #[cfg(feature = "json")]
 pub(crate) mod json_source;