Merge pull request #382 from Malax/build-plan-refactor

BuildPlan Metadata Support

libcnb-data/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 - Make `BuildPlan`'s `or` field public. ([#381](https://github.com/Malax/libcnb.rs/pull/381))
+- Add way to construct `Require` with metadata field and integrate with `BuildPlanBuilder`. ([#382](https://github.com/Malax/libcnb.rs/pull/382))
+- Add way to deserialize `Entry` metadata into a custom type. ([#382](https://github.com/Malax/libcnb.rs/pull/382))
 
 ## [0.5.0] 2022-02-28
 

libcnb-data/src/build_plan.rs

@@ -37,8 +37,8 @@ impl BuildPlanBuilder {
         self
     }
 
-    pub fn requires(mut self, name: impl AsRef<str>) -> Self {
-        self.current_requires.push(Require::new(name.as_ref()));
+    pub fn requires(mut self, require: impl Into<Require>) -> Self {
+        self.current_requires.push(require.into());
         self
     }
 
@@ -105,6 +105,29 @@ impl Require {
             metadata: Table::new(),
         }
     }
+
+    /// Convert a Serializable struct and store it as a toml Table for metadata
+    ///
+    /// # Errors
+    /// This will return error for any normal TOML serialization error as well if it's not
+    /// possible to serialize as a TOML Table.
+    pub fn metadata<T: Serialize>(&mut self, metadata: T) -> Result<(), toml::ser::Error> {
+        if let toml::Value::Table(table) = toml::Value::try_from(metadata)? {
+            self.metadata = table;
+
+            Ok(())
+        } else {
+            Err(toml::ser::Error::Custom(String::from(
+                "Could not be serialized as a TOML Table.",
+            )))
+        }
+    }
+}
+
+impl<S: Into<String>> From<S> for Require {
+    fn from(s: S) -> Self {
+        Require::new(s)
+    }
 }
 
 #[cfg(test)]
@@ -119,4 +142,23 @@ mod tests {
 
         assert!(toml::to_string(&build_plan).is_ok());
     }
+
+    #[test]
+    fn it_serializes_metadata() {
+        #[derive(Serialize)]
+        struct Metadata {
+            foo: String,
+        }
+
+        let mut require = Require::new("foo");
+        let metadata = Metadata {
+            foo: String::from("bar"),
+        };
+        let result = require.metadata(metadata);
+        assert!(result.is_ok());
+        assert_eq!(
+            require.metadata.get("foo"),
+            Some(&toml::Value::String(String::from("bar")))
+        );
+    }
 }

libcnb-data/src/buildpack_plan.rs

@@ -16,6 +16,20 @@ pub struct Entry {
     pub metadata: Table,
 }
 
+impl Entry {
+    /// Deserializes Metadata to a type T that implements Deserialize
+    ///
+    /// # Errors
+    /// This will return an error if it's not possible to serialize from a TOML Table into a T
+    pub fn metadata<'de, T>(&self) -> Result<T, toml::de::Error>
+    where
+        T: Deserialize<'de>,
+    {
+        // All toml `Value`s have `try_into()` which converts them to a `T` if `Deserialize` and `Deserializer` is implemented for `T`. Sadly, the `Table` type we use in `Entry` is not a `Value` so we need to make it one by wrapping it. We cannot wrap directly in `Entry` since that would allow users to put non-table TOML values as metadata. As outlined earlier, we can't get around the clone since we're only borrowing the metadata.
+        toml::Value::Table(self.metadata.clone()).try_into()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -50,4 +64,29 @@ name = "rust"
         let result = toml::from_str::<BuildpackPlan>(toml);
         assert!(result.is_ok());
     }
+
+    #[test]
+    fn it_deserializes_metadata() {
+        #[derive(Deserialize, Eq, PartialEq, Debug)]
+        struct Metadata {
+            foo: String,
+        }
+
+        let mut metadata = Table::new();
+        metadata.insert(
+            String::from("foo"),
+            toml::Value::String(String::from("bar")),
+        );
+        let entry = Entry {
+            name: String::from("foo"),
+            metadata,
+        };
+
+        assert_eq!(
+            entry.metadata(),
+            Ok(Metadata {
+                foo: String::from("bar"),
+            })
+        );
+    }
 }