fix models again

patch-db-macro-internals/src/lib.rs

@@ -8,30 +8,14 @@ use syn::punctuated::Punctuated;
 use syn::spanned::Spanned;
 use syn::token::{Comma, Paren, Pub};
 use syn::{
-    Attribute, Data, DataEnum, DataStruct, DeriveInput, Error, Fields, GenericArgument, Ident, Lit,
-    LitInt, LitStr, MetaNameValue, Path, PathArguments, Type, VisPublic, VisRestricted, Visibility,
+    Attribute, Data, DataEnum, DataStruct, DeriveInput, Error, Fields, Ident, Lit, LitInt, LitStr,
+    MetaNameValue, Path, Type, VisRestricted, Visibility,
 };
 
 pub fn build_model(item: &DeriveInput) -> TokenStream {
-    let mut model_name = None;
-    for arg in item
-        .attrs
-        .iter()
-        .filter(|attr| attr.path.is_ident("model"))
-        .map(|attr| attr.parse_args::<MetaNameValue>().unwrap())
-    {
-        match arg {
-            MetaNameValue {
-                path,
-                lit: Lit::Str(s),
-                ..
-            } if path.is_ident("name") => model_name = Some(s.parse().unwrap()),
-            _ => (),
-        }
-    }
     let res = match &item.data {
-        Data::Struct(struct_ast) => build_model_struct(item, struct_ast, model_name),
-        Data::Enum(enum_ast) => build_model_enum(item, enum_ast, model_name),
+        Data::Struct(struct_ast) => build_model_struct(item, struct_ast),
+        Data::Enum(enum_ast) => build_model_enum(item, enum_ast),
         _ => panic!("Models can only be created for Structs and Enums"),
     };
     if let Some(dbg) = item.attrs.iter().find(|a| a.path.is_ident("macro_debug")) {
@@ -83,7 +67,6 @@ struct ChildInfo {
     name: Ident,
     accessor: Option<Lit>,
     ty: Type,
-    has_model: bool,
 }
 impl ChildInfo {
     fn from_fields(serde_rename_all: &Option<String>, fields: &Fields) -> Vec<Self> {
@@ -93,7 +76,6 @@ impl ChildInfo {
                 for field in &f.named {
                     let ident = field.ident.clone().unwrap();
                     let ty = field.ty.clone();
-                    let has_model = field.attrs.iter().any(|attr| attr.path.is_ident("model"));
                     let accessor = if field
                         .attrs
                         .iter()
@@ -114,7 +96,6 @@ impl ChildInfo {
                         name: ident,
                         accessor,
                         ty,
-                        has_model,
                     })
                 }
             }
@@ -122,7 +103,6 @@ impl ChildInfo {
                 for (i, field) in f.unnamed.iter().enumerate() {
                     let ident = Ident::new(&format!("idx_{i}"), field.span());
                     let ty = field.ty.clone();
-                    let has_model = field.attrs.iter().any(|attr| attr.path.is_ident("model"));
                     let accessor = if f.unnamed.len() > 1 {
                         Some(Lit::Int(LitInt::new(
                             &format!("{}", i),
@@ -136,7 +116,6 @@ impl ChildInfo {
                         name: ident,
                         accessor,
                         ty,
-                        has_model,
                     })
                 }
             }
@@ -146,27 +125,6 @@ impl ChildInfo {
     }
 }
 
-fn separate_option(ty: &Type) -> (bool, &Type) {
-    match ty {
-        Type::Path(p) => {
-            if let Some(s) = p.path.segments.first() {
-                if s.ident == "Option" {
-                    if let PathArguments::AngleBracketed(a) = &s.arguments {
-                        if a.args.len() == 1 {
-                            if let GenericArgument::Type(a) = &a.args[0] {
-                                return (true, a);
-                            }
-                        }
-                    }
-                }
-            }
-        }
-        _ => (),
-    }
-
-    (false, ty)
-}
-
 struct Fns {
     impl_fns: TokenStream,
     impl_mut_fns: TokenStream,
@@ -180,9 +138,10 @@ fn impl_fns(children: &[ChildInfo]) -> Fns {
         name,
         accessor,
         ty,
-        has_model,
     } in children
     {
+        let name_owned = Ident::new(&format!("into_{name}"), name.span());
+        let name_mut = Ident::new(&format!("as_{name}_mut"), name.span());
         let vis = match vis {
             Visibility::Inherited => Visibility::Restricted(VisRestricted {
                 pub_token: Pub::default(),
@@ -211,54 +170,38 @@ fn impl_fns(children: &[ChildInfo]) -> Fns {
             }
             a => a.clone(),
         };
-        let (optional, ty) = separate_option(ty);
-        let (model_ty, model_mut_ty) = if *has_model {
-            (
-                quote_spanned! { name.span() =>
-                    <#ty as patch_db::HasModel>::Model
-                },
-                quote_spanned! { name.span() =>
-                    <<#ty as patch_db::HasModel>::Model as patch_db::Model>::Mut<'a>
-                },
-            )
+        let accessor_owned = if let Some(accessor) = accessor {
+            quote! {
+                {
+                    #[allow(unused_imports)]
+                    use patch_db::value::index::Index;
+                    #accessor.index_into_owned(v).unwrap_or_default()
+                }
+            }
         } else {
-            (
-                quote_spanned! { name.span() =>
-                    patch_db::GenericModel::<#ty>
-                },
-                quote_spanned! { name.span() =>
-                    patch_db::GenericModelMut::<'a, #ty>
-                },
-            )
+            quote! { v }
         };
-        let accessor = if let Some(accessor) = accessor {
-            quote! { [#accessor] }
+        let accessor_mut = if let Some(accessor) = accessor {
+            quote! {
+                {
+                    #[allow(unused_imports)]
+                    use patch_db::value::index::Index;
+                    #accessor.index_or_insert(v)
+                }
+            }
         } else {
-            quote! {}
+            quote! { v }
         };
-        if optional {
-            impl_fns.extend(quote_spanned! { name.span() =>
-                #vis fn #name (&self) -> patch_db::OptionModel<#model_ty> {
-                    <patch_db::OptionModel::<#model_ty> as patch_db::Model>::new((**self) #accessor .clone())
-                }
-            });
-            impl_mut_fns.extend(quote_spanned! { name.span() =>
-                #vis fn #name (&'a mut self) -> patch_db::OptionModelMut<'a, #model_mut_ty> {
-                    <patch_db::OptionModelMut::<'a, #model_mut_ty> as patch_db::ModelMut<'a>>::new(&mut (**self) #accessor)
-                }
-            });
-        } else {
-            impl_fns.extend(quote_spanned! { name.span() =>
-                #vis fn #name (&self) -> #model_ty {
-                    <#model_ty as patch_db::Model>::new((**self) #accessor .clone())
-                }
-            });
-            impl_mut_fns.extend(quote_spanned! { name.span() =>
-                #vis fn #name (&'a mut self) -> #model_mut_ty {
-                    <#model_mut_ty as patch_db::ModelMut<'a>>::new(&mut (**self) #accessor)
-                }
-            });
-        }
+        impl_fns.extend(quote_spanned! { name.span() =>
+            #vis fn #name_owned (self) -> patch_db::Model::<#ty> {
+                self.transmute(|v| #accessor_owned)
+            }
+        });
+        impl_mut_fns.extend(quote_spanned! { name.span() =>
+            #vis fn #name_mut (&mut self) -> &mut patch_db::Model::<#ty> {
+                self.transmute_mut(|v| #accessor_mut)
+            }
+        });
     }
     Fns {
         impl_fns,
@@ -266,17 +209,7 @@ fn impl_fns(children: &[ChildInfo]) -> Fns {
     }
 }
 
-fn build_model_struct(
-    base: &DeriveInput,
-    ast: &DataStruct,
-    module_name: Option<Ident>,
-) -> TokenStream {
-    let module_name = module_name.unwrap_or_else(|| {
-        Ident::new(
-            &format!("{}_model", heck::AsSnakeCase(base.ident.to_string())),
-            proc_macro2::Span::call_site(),
-        )
-    });
+fn build_model_struct(base: &DeriveInput, ast: &DataStruct) -> TokenStream {
     let serde_rename_all = base
         .attrs
         .iter()
@@ -289,82 +222,46 @@ fn build_model_struct(
         });
     let children = ChildInfo::from_fields(&serde_rename_all, &ast.fields);
     let name = &base.ident;
-    let vis = &base.vis;
     let Fns {
         impl_fns,
         impl_mut_fns,
     } = impl_fns(&children);
     quote! {
-        impl patch_db::HasModel for #name {
-            type Model = #module_name::Model;
-        }
-        #vis mod #module_name {
-            use super::*;
-
-            #[derive(Debug)]
-            pub struct Model(patch_db::Value);
-            impl patch_db::Model for Model {
-                type T = #name;
-                type Mut<'a> = ModelMut<'a>;
-                fn new(value: patch_db::Value) -> Self {
-                    Self(value)
-                }
-                fn into_inner(self) -> patch_db::Value {
-                    self.0
-                }
-            }
-            impl ::core::ops::Deref for Model {
-                type Target = patch_db::Value;
-                fn deref(&self) -> &Self::Target {
-                    &self.0
-                }
-            }
-            impl ::core::ops::DerefMut for Model {
-                fn deref_mut(&mut self) -> &mut Self::Target {
-                    &mut self.0
-                }
-            }
-            impl Model {
-                #impl_fns
-            }
-
-            #[derive(Debug)]
-            pub struct ModelMut<'a>(&'a mut patch_db::Value);
-            impl<'a> patch_db::ModelMut<'a> for ModelMut<'a> {
-                type T = #name;
-                fn new(value: &'a mut patch_db::Value) -> Self {
-                    Self(value)
-                }
-                fn into_inner(self) -> &'a mut patch_db::Value {
-                    self.0
-                }
-            }
-            impl<'a> ::core::ops::Deref for ModelMut<'a> {
-                type Target = patch_db::Value;
-                fn deref(&self) -> &Self::Target {
-                    &*self.0
-                }
-            }
-            impl<'a> ::core::ops::DerefMut for ModelMut<'a> {
-                fn deref_mut(&mut self) -> &mut Self::Target {
-                    self.0
-                }
-            }
-            impl<'a> ModelMut<'a> {
-                #impl_mut_fns
-            }
+        impl patch_db::HasModel for #name {}
+        impl patch_db::Model<#name> {
+            #impl_fns
+            #impl_mut_fns
         }
     }
 }
 
-fn build_model_enum(base: &DeriveInput, ast: &DataEnum, module_name: Option<Ident>) -> TokenStream {
-    let module_name = module_name.unwrap_or_else(|| {
-        Ident::new(
-            &format!("{}_model", heck::AsSnakeCase(base.ident.to_string())),
-            proc_macro2::Span::call_site(),
-        )
-    });
-    let mut children = Vec::new();
+fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
+    let mut match_name = None;
+    let mut match_name_mut = None;
+    for arg in base
+        .attrs
+        .iter()
+        .filter(|attr| attr.path.is_ident("model"))
+        .map(|attr| attr.parse_args::<MetaNameValue>().unwrap())
+    {
+        match arg {
+            MetaNameValue {
+                path,
+                lit: Lit::Str(s),
+                ..
+            } if path.is_ident("match") => match_name = Some(s.parse().unwrap()),
+            MetaNameValue {
+                path,
+                lit: Lit::Str(s),
+                ..
+            } if path.is_ident("match_mut") => match_name_mut = Some(s.parse().unwrap()),
+            _ => (),
+        }
+    }
+    let match_name = match_name
+        .unwrap_or_else(|| Ident::new(&format!("{}MatchModel", base.ident), Span::call_site()));
+    let match_name_mut = match_name_mut
+        .unwrap_or_else(|| Ident::new(&format!("{}MatchModelMut", base.ident), Span::call_site()));
     let serde_rename_all = base
         .attrs
         .iter()
@@ -408,55 +305,40 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum, module_name: Option<Iden
         .collect();
     let mut model_variants = TokenStream::new();
     let mut mut_model_variants = TokenStream::new();
-    let mut decl_model_variants = TokenStream::new();
-    let mut into_inner = TokenStream::new();
-    let mut deref = TokenStream::new();
-    let mut deref_mut = TokenStream::new();
-    let mut mut_into_inner = TokenStream::new();
-    let mut mut_deref = TokenStream::new();
-    let mut mut_deref_mut = TokenStream::new();
     let (impl_new, impl_new_mut) = if let Some(Lit::Str(tag)) = serde_tag.remove("tag") {
-        children.push(ChildInfo {
-            vis: Visibility::Public(VisPublic {
-                pub_token: Pub::default(),
-            }),
-            name: Ident::new("tag", tag.span()),
-            accessor: Some(Lit::Str(tag.clone())),
-            ty: Type::Path(syn::TypePath {
-                qself: None,
-                path: Path::from(Ident::new("String", tag.span())),
-            }),
-            has_model: false,
-        });
         if let Some(Lit::Str(content)) = serde_tag.remove("content") {
             let mut tag_variants = TokenStream::new();
             let mut tag_variants_mut = TokenStream::new();
             for variant in &ast.variants {
                 let variant_name = &variant.ident;
-                let variant_model =
-                    Ident::new(&format!("{}Model", variant_name), variant_name.span());
-                let variant_model_mut =
-                    Ident::new(&format!("{}ModelMut", variant_name), variant_name.span());
                 let variant_accessor =
                     get_accessor(&serde_rename_all, &variant.attrs, variant_name);
                 tag_variants.extend(quote_spanned! { variant_name.span() =>
-                    Some(#variant_accessor) => Model::#variant_name(#variant_model(value[#content].clone())),
+                    Some(#variant_accessor) => #match_name::#variant_name(self.transmute(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #content.index_into_owned(v).unwrap_or_default()
+                    })),
                 });
                 tag_variants_mut.extend(quote_spanned! { variant_name.span() =>
-                    Some(#variant_accessor) => ModelMut::#variant_name(#variant_model_mut(&mut value[#content])),
+                    Some(#variant_accessor) => #match_name_mut::#variant_name(self.transmute(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #content.index_or_insert(v)
+                    })),
                 });
             }
             (
                 quote! {
-                    match value[#tag].as_str() {
+                    match self[#tag].as_str() {
                         #tag_variants
-                        _ => Model::Error(value),
+                        _ => #match_name::Error(self.into_inner()),
                     }
                 },
                 quote! {
-                    match value[#tag].as_str() {
+                    match self[#tag].as_str() {
                         #tag_variants_mut
-                        _ => ModelMut::Error(value),
+                        _ => #match_name_mut::Error(&mut *self),
                     }
                 },
             )
@@ -465,30 +347,34 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum, module_name: Option<Iden
             let mut tag_variants_mut = TokenStream::new();
             for variant in &ast.variants {
                 let variant_name = &variant.ident;
-                let variant_model =
-                    Ident::new(&format!("{}Model", variant_name), variant_name.span());
-                let variant_model_mut =
-                    Ident::new(&format!("{}ModelMut", variant_name), variant_name.span());
                 let variant_accessor =
                     get_accessor(&serde_rename_all, &variant.attrs, variant_name);
                 tag_variants.extend(quote_spanned! { variant_name.span() =>
-                    Some(#variant_accessor) => Model::#variant_name(#variant_model(value)),
+                    Some(#variant_accessor) => #match_name::#variant_name(self.transmute(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #variant_accessor.index_into_owned(v).unwrap_or_default()
+                    })),
                 });
                 tag_variants_mut.extend(quote_spanned! { variant_name.span() =>
-                    Some(#variant_accessor) => ModelMut::#variant_name(#variant_model_mut(value)),
+                    Some(#variant_accessor) => #match_name_mut::#variant_name(self.transmute(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #variant_accessor.index_or_insert(v)
+                    })),
                 });
             }
             (
                 quote! {
-                    match value[#tag].as_str() {
+                    match self[#tag].as_str() {
                         #tag_variants
-                        _ => Model::Error(value),
+                        _ => #match_name::Error(self.into_inner()),
                     }
                 },
                 quote! {
-                    match value[#tag].as_str() {
+                    match self[#tag].as_str() {
                         #tag_variants_mut
-                        _ => ModelMut::Error(value),
+                        _ => #match_name_mut::Error(&mut *self),
                     }
                 },
             )
@@ -498,213 +384,83 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum, module_name: Option<Iden
         let mut tag_variants_mut = TokenStream::new();
         for variant in &ast.variants {
             let variant_name = &variant.ident;
-            let variant_model = Ident::new(&format!("{}Model", variant_name), variant_name.span());
-            let variant_model_mut =
-                Ident::new(&format!("{}ModelMut", variant_name), variant_name.span());
             let variant_accessor = get_accessor(&serde_rename_all, &variant.attrs, variant_name);
             tag_variants.extend(quote_spanned! { variant_name.span() =>
                 if value.as_object().map(|o| o.contains_key(#variant_accessor)).unwrap_or(false) {
-                    Model::#variant_name(#variant_model(value[#variant_accessor].clone()))
+                    #match_name::#variant_name(self.transmute(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #variant_accessor.index_into_owned(v).unwrap_or_default()
+                    }))
                 } else
             });
             tag_variants_mut.extend(quote_spanned! { variant_name.span() =>
                 if value.as_object().map(|o| o.contains_key(#variant_accessor)).unwrap_or(false) {
-                    ModelMut::#variant_name(#variant_model_mut(&mut value[#variant_accessor]))
+                    #match_name_mut::#variant_name(self.transmute(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #variant_accessor.index_or_insert(v)
+                    }))
                 } else
             });
         }
         (
             quote! {
                 #tag_variants {
-                    Model::Error(value),
+                    #match_name::Error(self.into_inner()),
                 }
             },
             quote! {
                 #tag_variants_mut {
-                    ModelMut::Error(value),
+                    #match_name_mut::Error(&mut *self),
                 }
             },
         )
     };
     for variant in &ast.variants {
         let name = &variant.ident;
-        let model_name = Ident::new(&format!("{}Model", variant.ident), variant.ident.span());
-        let model_name_mut =
-            Ident::new(&format!("{}ModelMut", variant.ident), variant.ident.span());
-        let serde_rename_all = variant
-            .attrs
-            .iter()
-            .filter(|attr| attr.path.is_ident("serde"))
-            .filter_map(|attr| attr.parse_args::<MetaNameValue>().ok())
-            .filter(|nv| nv.path.is_ident("rename_all"))
-            .find_map(|nv| match nv.lit {
-                Lit::Str(s) => Some(s.value()),
-                _ => None,
-            });
+        let ty = match &variant.fields {
+            Fields::Unnamed(a) if a.unnamed.len() == 1 => &a.unnamed.first().unwrap().ty,
+            a => {
+                return Error::new(
+                    a.span(),
+                    "Can only derive HasModel for enums with newtype variants",
+                )
+                .into_compile_error()
+            }
+        };
         model_variants.extend(quote_spanned! { name.span() =>
-            #name(#model_name),
+            #name(patch_db::Model<#ty>),
         });
         mut_model_variants.extend(quote_spanned! { name.span() =>
-            #name(#model_name_mut<'a>),
-        });
-        let children: Vec<_> = ChildInfo::from_fields(&serde_rename_all, &variant.fields)
-            .into_iter()
-            .map(|c| ChildInfo {
-                vis: Visibility::Public(VisPublic {
-                    pub_token: Pub::default(),
-                }),
-                ..c
-            })
-            .collect();
-        let Fns {
-            impl_fns,
-            impl_mut_fns,
-        } = impl_fns(&children);
-        decl_model_variants.extend(quote_spanned! { name.span() =>
-            #[derive(Debug)]
-            pub struct #model_name(patch_db::Value);
-            impl ::core::ops::Deref for #model_name {
-                type Target = patch_db::Value;
-                fn deref(&self) -> &Self::Target {
-                    &self.0
-                }
-            }
-            impl ::core::ops::DerefMut for #model_name {
-                fn deref_mut(&mut self) -> &mut Self::Target {
-                    &mut self.0
-                }
-            }
-            impl #model_name {
-                #impl_fns
-            }
-
-            #[derive(Debug)]
-            pub struct #model_name_mut<'a>(&'a mut patch_db::Value);
-            impl<'a> ::core::ops::Deref for #model_name_mut<'a> {
-                type Target = patch_db::Value;
-                fn deref(&self) -> &Self::Target {
-                    &*self.0
-                }
-            }
-            impl<'a> ::core::ops::DerefMut for #model_name_mut<'a> {
-                fn deref_mut(&mut self) -> &mut Self::Target {
-                    self.0
-                }
-            }
-            impl<'a> #model_name_mut<'a> {
-                #impl_mut_fns
-            }
-        });
-        into_inner.extend(quote_spanned! { name.span() =>
-            Model::#name(a) => a.0,
-        });
-        deref.extend(quote_spanned! { name.span() =>
-            Model::#name(a) => &a.0,
-        });
-        deref_mut.extend(quote_spanned! { name.span() =>
-            Model::#name(a) => &mut a.0,
-        });
-        mut_into_inner.extend(quote_spanned! { name.span() =>
-            ModelMut::#name(a) => a.0,
-        });
-        mut_deref.extend(quote_spanned! { name.span() =>
-            ModelMut::#name(a) => &*a,
-        });
-        mut_deref_mut.extend(quote_spanned! { name.span() =>
-            ModelMut::#name(a) => &mut *a,
+            #name(&'a mut patch_db::Model<#ty>),
         });
     }
     let name = &base.ident;
     let vis = &base.vis;
-    let Fns {
-        impl_fns,
-        impl_mut_fns,
-    } = impl_fns(&children);
     quote! {
-        impl patch_db::HasModel for #name {
-            type Model = #module_name::Model;
+        impl patch_db::HasModel for #name {}
+
+        impl patch_db::Model<#name> {
+            #vis fn matchable(&self) -> #match_name {
+                #impl_new
+            }
         }
-        #vis mod #module_name {
-            use super::*;
 
-            #[derive(Debug)]
-            pub enum Model {
-                #model_variants
-                Error(patch_db::Value),
-            }
-            impl patch_db::Model for Model {
-                type T = #name;
-                type Mut<'a> = ModelMut<'a>;
-                fn new(value: patch_db::Value) -> Self {
-                    #impl_new
-                }
-                fn into_inner(self) -> patch_db::Value {
-                    match self {
-                        #into_inner
-                        Model::Error(a) => a,
-                    }
-                }
-            }
-            impl ::core::ops::Deref for Model {
-                type Target = patch_db::Value;
-                fn deref(&self) -> &Self::Target {
-                    match self {
-                        #deref
-                        Model::Error(a) => &a,
-                    }
-                }
-            }
-            impl ::core::ops::DerefMut for Model {
-                fn deref_mut(&mut self) -> &mut Self::Target {
-                    match self {
-                        #deref_mut
-                        Model::Error(a) => &mut a,
-                    }
-                }
-            }
-            impl Model {
-                #impl_fns
-            }
+        #vis enum #match_name {
+            #model_variants
+            Error(patch_db::Value),
+        }
 
-            #[derive(Debug)]
-            pub enum ModelMut<'a> {
-                #mut_model_variants
-                Error(&'a mut patch_db::Value),
-            }
-            impl<'a> patch_db::ModelMut<'a> for ModelMut<'a> {
-                type T = #name;
-                fn new(value: &'a mut patch_db::Value) -> Self {
-                    #impl_new_mut
-                }
-                fn into_inner(self) -> &'a mut patch_db::Value {
-                    match self {
-                        #mut_into_inner
-                        ModelMut::Error(a) => a,
-                    }
-                }
-            }
-            impl<'a> ::core::ops::Deref for ModelMut<'a> {
-                type Target = patch_db::Value;
-                fn deref(&self) -> &Self::Target {
-                    match self {
-                        #mut_deref
-                        ModelMut::Error(a) => &*a,
-                    }
-                }
-            }
-            impl<'a> ::core::ops::DerefMut for ModelMut<'a> {
-                fn deref_mut(&mut self) -> &mut Self::Target {
-                    match self {
-                        #mut_deref_mut
-                        ModelMut::Error(a) => a,
-                    }
-                }
-            }
-            impl<'a> ModelMut<'a> {
-                #impl_mut_fns
+        impl patch_db::Model<#name> {
+            #vis fn matchable<'a>(&'a self) -> #match_name_mut<'a> {
+                #impl_new_mut
             }
+        }
 
-            #decl_model_variants
+        #vis enum #match_name_mut<'a> {
+            #mut_model_variants
+            Error(&'a mut patch_db::Value),
         }
     }
 }

patch-db/src/lib.rs

@@ -16,9 +16,7 @@ mod test;
 
 pub use imbl_value as value;
 pub use imbl_value::Value;
-pub use model::{
-    GenericModel, GenericModelMut, HasModel, Model, ModelMut, OptionModel, OptionModelMut,
-};
+pub use model::{HasModel, Model, ModelExt};
 pub use patch::{DiffPatch, Dump, Revision};
 pub use patch_db_macro::HasModel;
 pub use store::{PatchDb, Store};

patch-db/src/model.rs

@@ -1,24 +1,71 @@
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
 
-use imbl_value::Value;
+use imbl::OrdSet;
+use imbl_value::{InternedString, Value};
 use serde::de::DeserializeOwned;
 use serde::Serialize;
 
-pub trait HasModel {
-    type Model: Model;
+pub trait HasModel {}
+
+/// &mut Model<T> <=> &mut Value
+
+#[repr(transparent)]
+#[derive(Debug)]
+pub struct Model<T> {
+    value: Value,
+    phantom: PhantomData<T>,
+}
+impl<T> Clone for Model<T> {
+    fn clone(&self) -> Self {
+        Self {
+            value: self.value.clone(),
+            phantom: PhantomData,
+        }
+    }
+}
+impl<T> Deref for Model<T> {
+    type Target = Value;
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}
+impl<T> DerefMut for Model<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.value
+    }
+}
+impl<T> Model<T> {
+    pub fn new(value: Value) -> Self {
+        Self {
+            value,
+            phantom: PhantomData,
+        }
+    }
+    pub fn into_inner(self) -> Value {
+        self.value
+    }
+    pub fn transmute<U>(self, f: impl FnOnce(Value) -> Value) -> Model<U> {
+        Model {
+            value: f(self.value),
+            phantom: PhantomData,
+        }
+    }
+    pub fn transmute_mut<'a, U>(
+        &'a mut self,
+        f: impl for<'c> FnOnce(&'c mut Value) -> &'c mut Value,
+    ) -> &'a mut Model<U> {
+        unsafe {
+            std::mem::transmute::<&'a mut Value, &'a mut Model<U>>(f(std::mem::transmute::<
+                &'a mut Model<T>,
+                &'a mut Value,
+            >(self)))
+        }
+    }
 }
 
-pub trait Model: Deref<Target = Value> + DerefMut {
+pub trait ModelExt: Deref<Target = Value> + DerefMut {
     type T: DeserializeOwned + Serialize;
-    type Mut<'a>: ModelMut<'a>
-    where
-        Self: 'a;
-    fn new(value: Value) -> Self;
-    fn into_inner(self) -> Value;
-    fn as_mut<'a>(&'a mut self) -> Self::Mut<'a> {
-        Self::Mut::new(&mut *self)
-    }
     fn set(&mut self, value: &Self::T) -> Result<(), imbl_value::Error> {
         *self.deref_mut() = imbl_value::to_value(value)?;
         Ok(())
@@ -28,148 +75,132 @@ pub trait Model: Deref<Target = Value> + DerefMut {
     }
 }
 
-pub trait ModelMut<'a>: Deref<Target = Value> + DerefMut {
-    type T: DeserializeOwned + Serialize;
-    fn new(value: &'a mut Value) -> Self;
-    fn into_inner(self) -> &'a mut Value;
-    fn set(&mut self, value: &Self::T) -> Result<(), imbl_value::Error> {
-        *self.deref_mut() = imbl_value::to_value(value)?;
-        Ok(())
-    }
-    fn get(&self) -> Result<Self::T, imbl_value::Error> {
-        imbl_value::from_value(self.deref().clone())
-    }
-}
-
-pub struct GenericModel<T> {
-    value: Value,
-    phantom: PhantomData<T>,
-}
-impl<T> Deref for GenericModel<T> {
-    type Target = Value;
-    fn deref(&self) -> &Self::Target {
-        &self.value
-    }
-}
-impl<T> DerefMut for GenericModel<T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.value
-    }
-}
-impl<T: DeserializeOwned + Serialize> Model for GenericModel<T> {
+impl<T: DeserializeOwned + Serialize> ModelExt for Model<T> {
     type T = T;
-    type Mut<'a> = GenericModelMut<'a, T> where T: 'a;
-    fn new(value: Value) -> Self {
-        Self {
-            value,
-            phantom: PhantomData,
-        }
-    }
-    fn into_inner(self) -> Value {
-        self.value
-    }
 }
 
-pub struct GenericModelMut<'a, T> {
-    value: &'a mut Value,
-    phantom: PhantomData<T>,
-}
-impl<'a, T> Deref for GenericModelMut<'a, T> {
-    type Target = Value;
-    fn deref(&self) -> &Self::Target {
-        &*self.value
-    }
-}
-impl<'a, T> DerefMut for GenericModelMut<'a, T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        self.value
-    }
-}
-impl<'a, T: DeserializeOwned + Serialize> ModelMut<'a> for GenericModelMut<'a, T> {
-    type T = T;
-    fn new(value: &'a mut Value) -> Self {
-        Self {
-            value,
-            phantom: PhantomData,
-        }
-    }
-    fn into_inner(self) -> &'a mut Value {
-        self.value
-    }
-}
-
-pub struct OptionModel<T: Model> {
-    value: Value,
-    phantom: PhantomData<T>,
-}
-
-impl<T: Model> OptionModel<T> {
-    pub fn check(self) -> Option<T> {
+impl<T> Model<Option<T>> {
+    pub fn transpose(self) -> Option<Model<T>> {
         if self.is_null() {
             None
         } else {
-            Some(T::new(self.value))
+            Some(self.transmute(|a| a))
         }
     }
 }
-impl<T: Model> Deref for OptionModel<T> {
-    type Target = Value;
-    fn deref(&self) -> &Self::Target {
-        &self.value
-    }
-}
-impl<T: Model> DerefMut for OptionModel<T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.value
-    }
-}
-impl<T: Model> Model for OptionModel<T> {
-    type T = Option<T::T>;
-    type Mut<'a> = OptionModelMut<'a, T::Mut<'a>> where T: 'a;
-    fn new(value: Value) -> Self {
-        Self {
-            value,
-            phantom: PhantomData,
-        }
-    }
-    fn into_inner(self) -> Value {
-        self.value
-    }
-}
 
-pub struct OptionModelMut<'a, T: ModelMut<'a>> {
-    value: &'a mut Value,
-    phantom: PhantomData<T>,
+pub trait Map: DeserializeOwned + Serialize {
+    type Key;
+    type Value;
+    type Error: From<imbl_value::Error>;
 }
-impl<'a, T: ModelMut<'a>> OptionModelMut<'a, T> {
-    pub fn check(self) -> Option<T> {
-        if self.is_null() {
-            None
-        } else {
-            Some(T::new(self.value))
+
+impl<T: Map> Model<T>
+where
+    T::Key: DeserializeOwned + Ord + Clone,
+{
+    pub fn keys(&self) -> Result<OrdSet<T::Key>, T::Error> {
+        use serde::de::Error;
+        use serde::Deserialize;
+        match &**self {
+            Value::Object(o) => o
+                .keys()
+                .cloned()
+                .map(|k| {
+                    T::Key::deserialize(imbl_value::de::InternedStringDeserializer::from(k))
+                        .map_err(|e| {
+                            imbl_value::Error {
+                                kind: imbl_value::ErrorKind::Deserialization,
+                                source: e,
+                            }
+                            .into()
+                        })
+                })
+                .collect(),
+            v => Err(imbl_value::Error {
+                source: imbl_value::ErrorSource::custom(format!("expected object found {v}")),
+                kind: imbl_value::ErrorKind::Deserialization,
+            }
+            .into()),
         }
     }
 }
-impl<'a, T: ModelMut<'a>> Deref for OptionModelMut<'a, T> {
-    type Target = Value;
-    fn deref(&self) -> &Self::Target {
-        &*self.value
-    }
-}
-impl<'a, T: ModelMut<'a>> DerefMut for OptionModelMut<'a, T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        self.value
-    }
-}
-impl<'a, T: ModelMut<'a>> ModelMut<'a> for OptionModelMut<'a, T> {
-    type T = Option<T::T>;
-    fn new(value: &'a mut Value) -> Self {
-        Self {
-            value,
-            phantom: PhantomData,
+impl<T: Map> Model<T>
+where
+    T::Key: AsRef<str>,
+{
+    pub fn idx(self, key: &T::Key) -> Option<Model<T::Value>> {
+        match &*self {
+            Value::Object(o) if o.contains_key(key.as_ref()) => Some(self.transmute(|v| {
+                use imbl_value::index::Index;
+                key.as_ref().index_into_owned(v).unwrap()
+            })),
+            _ => None,
         }
     }
-    fn into_inner(self) -> &'a mut Value {
-        self.value
+}
+impl<T: Map> Model<T>
+where
+    T::Key: AsRef<str>,
+    T::Value: Serialize,
+{
+    pub fn insert(&mut self, key: &T::Key, value: &T::Value) -> Result<(), T::Error> {
+        use serde::ser::Error;
+        let v = imbl_value::to_value(value)?;
+        match &mut **self {
+            Value::Object(o) => {
+                o.insert(InternedString::intern(key.as_ref()), v);
+                Ok(())
+            }
+            _ => Err(imbl_value::Error {
+                source: imbl_value::ErrorSource::custom(format!("expected object found {v}")),
+                kind: imbl_value::ErrorKind::Serialization,
+            }
+            .into()),
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use crate as patch_db;
+    use imbl_value::json;
+
+    #[derive(crate::HasModel)]
+    // #[macro_debug]
+    struct Foo {
+        a: Bar,
+    }
+
+    #[derive(crate::HasModel)]
+    struct Bar {
+        b: String,
+    }
+
+    fn mutate_fn(v: &mut Model<Foo>) {
+        let mut a = v.as_a_mut();
+        a.as_b_mut().set(&"NotThis".into()).unwrap();
+        a.as_b_mut().set(&"Replaced".into()).unwrap();
+    }
+
+    #[test]
+    fn test() {
+        let mut model = Model::<Foo>::new(imbl_value::json!({
+            "a": {
+                "b": "ReplaceMe"
+            }
+        }));
+        mutate_fn(&mut model);
+        mutate_fn(&mut model);
+        assert_eq!(
+            &*model,
+            &imbl_value::json!({
+                "a": {
+                    "b": "Replaced"
+                }
+            })
+        )
     }
 }