Add Structable::get for accessing fields-by-name.

tokio-rs · Aug 30, 2022 · 0329906 · 0329906
1 parent 6c45408
commit 0329906
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Showing 10 changed files with 144 additions and 4 deletions.
diff --git a/tests/src/hello_world.rs b/tests/src/hello_world.rs
@@ -24,4 +24,13 @@ impl Structable for HelloWorld {
     fn definition(&self) -> StructDef<'_> {
         StructDef::new_static("HelloWorld", Fields::Named(HELLO_WORLD_FIELDS))
     }
+
+    fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+        if let Field::Named(field) = field {
+            if field.name() == HELLO_WORLD_FIELDS[0].name() {
+                return Some(Value::U32(self.id));
+            }
+        }
+        None
+    }
 }
diff --git a/tests/tests/structable.rs b/tests/tests/structable.rs
@@ -41,6 +41,15 @@ fn test_manual_static_impl() {
         fn definition(&self) -> StructDef<'_> {
             StructDef::new_static("MyStruct", Fields::Named(MY_STRUCT_FIELDS))
         }
+
+        fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+            match field {
+                Field::Named(field) if field.name() == "num" => Some(Value::U32(self.num)),
+                Field::Named(field) if field.name() == "list" => Some(Value::Listable(&self.list)),
+                Field::Named(field) if field.name() == "sub" => Some(Value::Structable(&self.sub)),
+                _ => None,
+            }
+        }
     }
 
     impl Valuable for SubStruct {
@@ -60,6 +69,13 @@ fn test_manual_static_impl() {
         fn definition(&self) -> StructDef<'_> {
             StructDef::new_static("SubStruct", Fields::Named(SUB_STRUCT_FIELDS))
         }
+
+        fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+            match field {
+                Field::Named(field) if field.name() == "sub" => Some(Value::String(&self.message)),
+                _ => None,
+            }
+        }
     }
 
     let my_struct = MyStruct {
@@ -118,6 +134,14 @@ fn test_manual_dyn_impl() {
         fn definition(&self) -> StructDef<'_> {
             StructDef::new_dynamic("MyStruct", Fields::Named(&[]))
         }
+
+        fn get(&self, field: Field) -> Option<Value<'_>> {
+            match field {
+                Field::Named(field) if field.name() == "foo" => Some(Value::U32(1)),
+                Field::Named(field) if field.name() == "bar" => Some(Value::String("two")),
+                _ => None,
+            }
+        }
     }
 
     let my_struct = MyStruct;

diff --git a/valuable-derive/src/expand.rs b/valuable-derive/src/expand.rs
@@ -17,6 +17,7 @@ fn derive_struct(input: &syn::DeriveInput, data: &syn::DataStruct) -> TokenStrea
     let name_literal = name.to_string();
     let visit_fields;
     let struct_def;
+    let get_branches: TokenStream;
     let mut named_fields_statics = None;
 
     match &data.fields {
@@ -33,6 +34,19 @@ fn derive_struct(input: &syn::DeriveInput, data: &syn::DataStruct) -> TokenStrea
                 )
             };
 
+            get_branches =
+                data.fields.iter().map(|field| {
+                    let field_name_ident = field.ident.as_ref();
+                    let field_name_str = field_name_ident.unwrap().to_string();
+                    quote! {
+                        ::valuable::Field::Named(field) if field.name() == #field_name_str => Some(::valuable::Valuable::as_value(&self.#field_name_ident)),
+                    }
+                }).collect();
+
+            quote! {
+                ::valuable::Field::Named(field) if field.name() == ""
+            };
+
             let fields = data.fields.iter().map(|field| {
                 let f = field.ident.as_ref();
                 let tokens = quote! {
@@ -58,6 +72,14 @@ fn derive_struct(input: &syn::DeriveInput, data: &syn::DataStruct) -> TokenStrea
                 )
             };
 
+            get_branches =
+                data.fields.iter().enumerate().map(|(i, _)| {
+                    let i = syn::Index::from(i);
+                    quote! {
+                        ::valuable::Field::Unnamed(f) if f == #i => Some(::valuable::Valuable::as_value(&self.#i)),
+                    }
+                }).collect();
+
             let indices = data.fields.iter().enumerate().map(|(i, field)| {
                 let index = syn::Index::from(i);
                 let tokens = quote! {
@@ -82,6 +104,13 @@ fn derive_struct(input: &syn::DeriveInput, data: &syn::DataStruct) -> TokenStrea
             fn definition(&self) -> ::valuable::StructDef<'_> {
                 #struct_def
             }
+
+            fn get(&self, field: ::valuable::Field<'_>) -> Option<::valuable::Value<'_>> {
+                match field {
+                    #get_branches
+                    _ => None,
+                }
+            }
         }
     };
 

diff --git a/valuable-serde/tests/test.rs b/valuable-serde/tests/test.rs
@@ -407,6 +407,14 @@ fn test_dyn_struct() {
         fn definition(&self) -> StructDef<'_> {
             StructDef::new_dynamic("Named", Fields::Named(&[]))
         }
+
+        fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+            match field {
+                Field::Unnamed(0) => Some(Value::U32(1)),
+                Field::Unnamed(1) => Some(Value::I32(-1)),
+                _ => None,
+            }
+        }
     }
 
     struct Unnamed;
@@ -426,6 +434,14 @@ fn test_dyn_struct() {
         fn definition(&self) -> StructDef<'_> {
             StructDef::new_dynamic("Unnamed", Fields::Unnamed(2))
         }
+
+        fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+            match field {
+                Field::Unnamed(0) => Some(Value::U32(1)),
+                Field::Unnamed(1) => Some(Value::I32(-1)),
+                _ => None,
+            }
+        }
     }
 
     assert_ser_tokens(

diff --git a/valuable/examples/hello_world.rs b/valuable/examples/hello_world.rs
@@ -16,6 +16,14 @@ impl Structable for HelloWorld {
     fn definition(&self) -> StructDef<'_> {
         StructDef::new_static("HelloWorld", Fields::Named(HELLO_WORLD_FIELDS))
     }
+
+    fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+        match field {
+            Field::Named(field) if field.name() == "hello" => Some(Value::String(self.hello)),
+            Field::Named(field) if field.name() == "world" => Some(Value::Structable(&self.world)),
+            _ => None,
+        }
+    }
 }
 
 impl Valuable for HelloWorld {
@@ -50,6 +58,13 @@ impl Structable for World {
     fn definition(&self) -> StructDef<'_> {
         StructDef::new_static("World", Fields::Named(WORLD_FIELDS))
     }
+
+    fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+        match field {
+            Field::Named(field) if field.name() == "answer" => Some(Value::Usize(self.answer)),
+            _ => None,
+        }
+    }
 }
 
 fn main() {

diff --git a/valuable/examples/indexing.rs b/valuable/examples/indexing.rs
@@ -0,0 +1,12 @@
+fn main() {
+    use valuable::{NamedField, NamedValues, Value};
+
+    let fields = [NamedField::new("foo"), NamedField::new("bar")];
+    let values = [Value::U32(123), Value::U32(456)];
+
+    let named_values = NamedValues::new(&fields, &values);
+
+    let field = &fields[0];
+
+    assert_eq!(named_values.get(field).and_then(Value::as_u32), Some(123));
+}
diff --git a/valuable/examples/print.rs b/valuable/examples/print.rs
@@ -50,7 +50,7 @@ impl Visit for Print {
     }
 
     fn visit_named_fields(&mut self, named_values: &NamedValues<'_>) {
-        for (field, value) in named_values {
+        for (field, value) in named_values.into_iter() {
             print!("{}- {}: ", self.0, field.name());
             value.visit(self);
         }

diff --git a/valuable/src/field.rs b/valuable/src/field.rs
@@ -10,6 +10,16 @@ pub enum Fields<'a> {
     Unnamed(usize),
 }
 
+/// A field, either named or positional, in a `Structable`.
+#[derive(Debug)]
+pub enum Field<'a> {
+    /// Named field.
+    Named(NamedField<'a>),
+
+    /// Unnamed (positional) field.
+    Unnamed(usize),
+}
+
 /// A named field
 #[derive(Debug, Clone, Copy)]
 pub struct NamedField<'a>(&'a str);

diff --git a/valuable/src/lib.rs b/valuable/src/lib.rs
@@ -124,7 +124,7 @@ mod enumerable;
 pub use enumerable::{EnumDef, Enumerable, Variant, VariantDef};
 
 mod field;
-pub use field::{Fields, NamedField};
+pub use field::{Field, Fields, NamedField};
 
 mod listable;
 pub use listable::Listable;

diff --git a/valuable/src/structable.rs b/valuable/src/structable.rs
@@ -109,6 +109,9 @@ pub trait Structable: Valuable {
     ///
     /// assert_eq!("MyStruct", my_struct.definition().name());
     fn definition(&self) -> StructDef<'_>;
+
+    /// Returns the value of the given field, if any.
+    fn get(&self, field: Field<'_>) -> Option<Value<'_>>;
 }
 
 /// A struct's name, fields, and other struct-level information.
@@ -178,7 +181,7 @@ pub enum StructDef<'a> {
     /// The struct stores field values in a `HashMap`.
     ///
     /// ```
-    /// use valuable::{Fields, NamedField, NamedValues, Structable, StructDef, Value, Valuable, Visit};
+    /// use valuable::{Field, Fields, NamedField, NamedValues, Structable, StructDef, Value, Valuable, Visit};
     /// use std::collections::HashMap;
     ///
     /// /// A dynamic struct
@@ -210,13 +213,20 @@ pub enum StructDef<'a> {
     ///     fn definition(&self) -> StructDef<'_> {
     ///         StructDef::new_dynamic(&self.name, Fields::Named(&[]))
     ///     }
+    ///
+    ///     fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+    ///         match field {
+    ///             Field::Named(field) => self.values.get(field.name()).map(|v| v.as_value()),
+    ///             _ => None,
+    ///         }
+    ///     }
     /// }
     /// ```
     ///
     /// Some fields are known statically.
     ///
     /// ```
-    /// use valuable::{Fields, NamedField, NamedValues, Structable, StructDef, Value, Valuable, Visit};
+    /// use valuable::{Field, Fields, NamedField, NamedValues, Structable, StructDef, Value, Valuable, Visit};
     /// use std::collections::HashMap;
     ///
     /// struct HalfStatic {
@@ -259,6 +269,17 @@ pub enum StructDef<'a> {
     ///             "HalfStatic",
     ///             Fields::Named(FIELDS))
     ///     }
+    ///
+    ///     fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+    ///         match field {
+    ///             Field::Named(field) if field.name() == "foo" => Some(self.foo.as_value()),
+    ///             Field::Named(field) if field.name() == "bar" => Some(self.bar.as_value()),
+    ///             Field::Named(field) => {
+    ///                 self.extra_values.get(field.name()).map(|v| v.as_value())
+    ///             },
+    ///             _ => None,
+    ///         }
+    ///     }
     /// }
     /// ```
     #[non_exhaustive]
@@ -478,6 +499,10 @@ macro_rules! deref {
                 fn definition(&self) -> StructDef<'_> {
                     T::definition(&**self)
                 }
+
+                fn get(&self, field: Field<'_>) -> Option<Value<'_>> {
+                    T::get(&**self, field)
+                }
             }
         )*
     };