Introduce DeserOpinions

.github/workflows/test.yml

@@ -8,7 +8,7 @@ on:
   merge_group:
 
 jobs:
-  build:
+  test:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
@@ -23,4 +23,5 @@ jobs:
       - name: Run tests
         shell: bash
         run: |
+          rustup toolchain install nightly --component miri
           just

Justfile

@@ -23,3 +23,8 @@ check:
       cargo run --features full,ahash --example "$example"
     done
     popd
+
+    just miri
+
+miri:
+    cargo +nightly miri run --example opinions -F json

merde/Cargo.toml

@@ -50,6 +50,11 @@ name = "infinite-stack"
 path = "examples/infinite-stack.rs"
 required-features = ["json"]
 
+[[example]]
+name = "opinions"
+path = "examples/opinions.rs"
+required-features = ["json"]
+
 [dependencies]
 merde_core = { version = "7.0.0", path = "../merde_core", optional = true }
 merde_json = { version = "6.2.1", path = "../merde_json", optional = true }

merde/examples/opinions.rs

@@ -0,0 +1,77 @@
+use merde::{CowStr, DeserOpinions, FieldSlot};
+
+fn main() {
+    let input_precise = r#"
+        { "foo_bar": "hello" }
+    "#;
+    let o: Owned = merde_json::from_str(input_precise).unwrap();
+    assert_eq!(o.foo_bar, "hello");
+    eprintln!("{o:#?}");
+
+    let input_camel_case = r#"
+        { "fooBar": "hello" }
+    "#;
+    let o: Owned = merde_json::from_str(input_camel_case).unwrap();
+    assert_eq!(o.foo_bar, "hello");
+    eprintln!("{o:#?}");
+
+    let input_too_many_fields = r#"
+        { "foo_bar": "hello", "foo_bar2": "world" }
+    "#;
+    assert!(merde_json::from_str::<Owned>(input_too_many_fields).is_err());
+    let o: OwnedRelaxed = merde_json::from_str(input_too_many_fields).unwrap();
+    assert_eq!(o.foo_bar, "hello");
+    eprintln!("{o:#?}");
+
+    let input_missing_field = r#"
+        {}
+    "#;
+    let o: Owned = merde_json::from_str(input_missing_field).unwrap();
+    assert_eq!(o.foo_bar, "(default)");
+    eprintln!("{o:#?}");
+}
+
+#[derive(Debug)]
+struct Owned {
+    foo_bar: String,
+}
+
+struct OwnedOpinions;
+
+impl DeserOpinions for OwnedOpinions {
+    fn deny_unknown_fields(&self) -> bool {
+        true
+    }
+
+    #[allow(clippy::needless_lifetimes)]
+    fn default_field_value<'s, 'borrow>(&self, key: &'borrow str, slot: FieldSlot<'s, 'borrow>) {
+        if key == "foo_bar" {
+            slot.fill::<String>("(default)".into());
+        }
+    }
+
+    fn map_key_name<'s>(&self, key: CowStr<'s>) -> CowStr<'s> {
+        if key == "fooBar" {
+            CowStr::Owned("foo_bar".into())
+        } else {
+            key
+        }
+    }
+}
+
+merde::derive! {
+    impl (Deserialize) for struct Owned {
+        foo_bar
+    } via OwnedOpinions
+}
+
+#[derive(Debug)]
+struct OwnedRelaxed {
+    foo_bar: String,
+}
+
+merde::derive! {
+    impl (Deserialize) for struct OwnedRelaxed {
+        foo_bar
+    }
+}