improved api

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

@@ -8,8 +8,9 @@ use syn::punctuated::Punctuated;
 use syn::spanned::Spanned;
 use syn::token::{Comma, Paren, Pub};
 use syn::{
-    Attribute, Data, DataEnum, DataStruct, DeriveInput, Error, Fields, Ident, Lit, LitInt, LitStr,
-    MetaNameValue, Path, Type, VisRestricted, Visibility,
+    Attribute, Data, DataEnum, DataStruct, DeriveInput, Error, Fields, GenericArgument, Ident, Lit,
+    LitInt, LitStr, Meta, MetaNameValue, Path, PathArguments, Type, TypePath, VisRestricted,
+    Visibility,
 };
 
 pub fn build_model(item: &DeriveInput) -> TokenStream {
@@ -126,12 +127,17 @@ impl ChildInfo {
 }
 
 struct Fns {
+    from_parts: TokenStream,
     impl_fns: TokenStream,
+    impl_ref_fns: TokenStream,
     impl_mut_fns: TokenStream,
 }
 
-fn impl_fns(children: &[ChildInfo]) -> Fns {
+fn impl_fns(model_ty: &Type, children: &[ChildInfo]) -> Fns {
+    let mut parts_args = TokenStream::new();
+    let mut parts_assignments = TokenStream::new();
     let mut impl_fns = TokenStream::new();
+    let mut impl_ref_fns = TokenStream::new();
     let mut impl_mut_fns = TokenStream::new();
     for ChildInfo {
         vis,
@@ -141,6 +147,7 @@ fn impl_fns(children: &[ChildInfo]) -> Fns {
     } in children
     {
         let name_owned = Ident::new(&format!("into_{name}"), name.span());
+        let name_ref = Ident::new(&format!("as_{name}"), name.span());
         let name_mut = Ident::new(&format!("as_{name}_mut"), name.span());
         let vis = match vis {
             Visibility::Inherited => Visibility::Restricted(VisRestricted {
@@ -181,6 +188,17 @@ fn impl_fns(children: &[ChildInfo]) -> Fns {
         } else {
             quote! { v }
         };
+        let accessor_ref = if let Some(accessor) = accessor {
+            quote! {
+                {
+                    #[allow(unused_imports)]
+                    use patch_db::value::index::Index;
+                    #accessor.index_into(v).unwrap_or(&patch_db::value::NULL)
+                }
+            }
+        } else {
+            quote! { v }
+        };
         let accessor_mut = if let Some(accessor) = accessor {
             quote! {
                 {
@@ -192,24 +210,128 @@ fn impl_fns(children: &[ChildInfo]) -> Fns {
         } else {
             quote! { v }
         };
+        let child_model_ty = replace_self(model_ty.clone(), &ty);
+        parts_args.extend(quote_spanned! { name.span() =>
+            #name: #child_model_ty,
+        });
+        parts_assignments.extend(quote_spanned! { name.span() =>
+            *#accessor_mut = #name.into_value();
+        });
         impl_fns.extend(quote_spanned! { name.span() =>
-            #vis fn #name_owned (self) -> patch_db::Model::<#ty> {
+            #vis fn #name_owned (self) -> #child_model_ty {
+                use patch_db::ModelExt;
                 self.transmute(|v| #accessor_owned)
             }
         });
+        impl_ref_fns.extend(quote_spanned! { name.span() =>
+            #vis fn #name_ref (&self) -> &#child_model_ty {
+                use patch_db::ModelExt;
+                self.transmute_ref(|v| #accessor_ref)
+            }
+        });
         impl_mut_fns.extend(quote_spanned! { name.span() =>
-            #vis fn #name_mut (&mut self) -> &mut patch_db::Model::<#ty> {
+            #vis fn #name_mut (&mut self) -> &mut #child_model_ty {
+                use patch_db::ModelExt;
                 self.transmute_mut(|v| #accessor_mut)
             }
         });
     }
     Fns {
+        from_parts: quote! {
+            pub fn from_parts(#parts_args) -> Self {
+                use patch_db::ModelExt;
+                let mut res = patch_db::value::json!({});
+                let v = &mut res;
+                #parts_assignments
+                Self::from_value(res)
+            }
+        },
         impl_fns,
+        impl_ref_fns,
         impl_mut_fns,
     }
 }
 
+fn replace_self(ty: Type, replace: &Type) -> Type {
+    match ty {
+        Type::Path(mut a) => Type::Path({
+            a.path.segments = a
+                .path
+                .segments
+                .into_iter()
+                .map(|mut s| {
+                    s.arguments = match s.arguments {
+                        PathArguments::AngleBracketed(mut a) => PathArguments::AngleBracketed({
+                            a.args = a
+                                .args
+                                .into_iter()
+                                .map(|a| match a {
+                                    GenericArgument::Type(Type::Path(a)) => {
+                                        GenericArgument::Type({
+                                            if a.path.is_ident("Self") {
+                                                replace.clone()
+                                            } else {
+                                                Type::Path(a)
+                                            }
+                                        })
+                                    }
+                                    a => a,
+                                })
+                                .collect();
+                            a
+                        }),
+                        a => a,
+                    };
+                    s
+                })
+                .collect();
+            a
+        }),
+        a => a,
+    }
+}
+
 fn build_model_struct(base: &DeriveInput, ast: &DataStruct) -> TokenStream {
+    let model_ty = match base
+        .attrs
+        .iter()
+        .filter(|attr| attr.path.is_ident("model"))
+        .filter_map(|attr| attr.parse_meta().ok())
+        .find_map(|meta| {
+            if let Meta::NameValue(a) = meta {
+                Some(a)
+            } else {
+                None
+            }
+        })
+        .ok_or_else(|| {
+            Error::new(
+                base.ident.span(),
+                "could not determine model type\n#[model = \"...\"] is required",
+            )
+        })
+        .and_then(|meta| {
+            if let Lit::Str(a) = meta.lit {
+                Ok(a)
+            } else {
+                Err(Error::new(
+                    meta.lit.span(),
+                    "syntax error: expected string literal",
+                ))
+            }
+        })
+        .and_then(|s| syn::parse_str::<Type>(&s.value()))
+    {
+        Ok(a) => a,
+        Err(e) => return e.into_compile_error(),
+    };
+    let model_ty_name = replace_self(
+        model_ty.clone(),
+        &Type::Path(TypePath {
+            qself: None,
+            path: base.ident.clone().into(),
+        }),
+    );
     let serde_rename_all = base
         .attrs
         .iter()
@@ -223,26 +345,73 @@ fn build_model_struct(base: &DeriveInput, ast: &DataStruct) -> TokenStream {
     let children = ChildInfo::from_fields(&serde_rename_all, &ast.fields);
     let name = &base.ident;
     let Fns {
+        from_parts,
         impl_fns,
+        impl_ref_fns,
         impl_mut_fns,
-    } = impl_fns(&children);
+    } = impl_fns(&model_ty, &children);
     quote! {
-        impl patch_db::HasModel for #name {}
-        impl patch_db::Model<#name> {
+        impl patch_db::HasModel for #name {
+            type Model = #model_ty;
+        }
+        impl #model_ty_name {
+            #from_parts
             #impl_fns
+            #impl_ref_fns
             #impl_mut_fns
         }
     }
 }
 
 fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
+    let model_ty = match base
+        .attrs
+        .iter()
+        .filter(|attr| attr.path.is_ident("model"))
+        .filter_map(|attr| attr.parse_meta().ok())
+        .find_map(|meta| {
+            if let Meta::NameValue(a) = meta {
+                Some(a)
+            } else {
+                None
+            }
+        })
+        .ok_or_else(|| {
+            Error::new(
+                base.ident.span(),
+                "could not determine model type\n#[model = \"...\"] is required",
+            )
+        })
+        .and_then(|meta| {
+            if let Lit::Str(a) = meta.lit {
+                Ok(a)
+            } else {
+                Err(Error::new(
+                    meta.lit.span(),
+                    "syntax error: expected string literal",
+                ))
+            }
+        })
+        .and_then(|s| syn::parse_str::<Type>(&s.value()))
+    {
+        Ok(a) => a,
+        Err(e) => return e.into_compile_error(),
+    };
+    let model_ty_name = replace_self(
+        model_ty.clone(),
+        &Type::Path(TypePath {
+            qself: None,
+            path: base.ident.clone().into(),
+        }),
+    );
     let mut match_name = None;
+    let mut match_name_ref = 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())
+        .filter_map(|attr| attr.parse_args::<MetaNameValue>().ok())
     {
         match arg {
             MetaNameValue {
@@ -250,6 +419,11 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
                 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_ref") => match_name_ref = Some(s.parse().unwrap()),
             MetaNameValue {
                 path,
                 lit: Lit::Str(s),
@@ -260,6 +434,8 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
     }
     let match_name = match_name
         .unwrap_or_else(|| Ident::new(&format!("{}MatchModel", base.ident), Span::call_site()));
+    let match_name_ref = match_name_ref
+        .unwrap_or_else(|| Ident::new(&format!("{}MatchModelRef", 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
@@ -304,10 +480,15 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
         })
         .collect();
     let mut model_variants = TokenStream::new();
+    let mut ref_model_variants = TokenStream::new();
     let mut mut_model_variants = TokenStream::new();
-    let (impl_new, impl_new_mut) = if let Some(Lit::Str(tag)) = serde_tag.remove("tag") {
+    let (impl_new, impl_unmatch, impl_new_ref, impl_new_mut) = if let Some(Lit::Str(tag)) =
+        serde_tag.remove("tag")
+    {
         if let Some(Lit::Str(content)) = serde_tag.remove("content") {
             let mut tag_variants = TokenStream::new();
+            let mut tag_variants_unmatch = TokenStream::new();
+            let mut tag_variants_ref = TokenStream::new();
             let mut tag_variants_mut = TokenStream::new();
             for variant in &ast.variants {
                 let variant_name = &variant.ident;
@@ -320,8 +501,22 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
                         #content.index_into_owned(v).unwrap_or_default()
                     })),
                 });
+                tag_variants_unmatch.extend(quote_spanned! { variant_name.span() =>
+                    #match_name::#variant_name(v) => Self::from_value({
+                        let mut a = patch_db::value::json!({ #tag: #variant_accessor });
+                        a[#content] = v.into_value();
+                        a
+                    }),
+                });
+                tag_variants_ref.extend(quote_spanned! { variant_name.span() =>
+                    Some(#variant_accessor) => #match_name_ref::#variant_name(self.transmute_ref(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #content.index_into(v).unwrap_or(&patch_db::value::NULL)
+                    })),
+                });
                 tag_variants_mut.extend(quote_spanned! { variant_name.span() =>
-                    Some(#variant_accessor) => #match_name_mut::#variant_name(self.transmute(|v| {
+                    Some(#variant_accessor) => #match_name_mut::#variant_name(self.transmute_mut(|v| {
                         #[allow(unused_imports)]
                         use patch_db::value::index::Index;
                         #content.index_or_insert(v)
@@ -330,13 +525,29 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
             }
             (
                 quote! {
-                    match self[#tag].as_str() {
+                    use patch_db::ModelExt;
+                    match self.as_value()[#tag].as_str() {
                         #tag_variants
                         _ => #match_name::Error(self.into_inner()),
                     }
                 },
                 quote! {
-                    match self[#tag].as_str() {
+                    use patch_db::ModelExt;
+                    match value {
+                        #tag_variants_unmatch
+                        #match_name::Error(v) => Self::from_value(v),
+                    }
+                },
+                quote! {
+                    use patch_db::ModelExt;
+                    match self.as_value()[#tag].as_str() {
+                        #tag_variants_ref
+                        _ => #match_name_ref::Error(&*self),
+                    }
+                },
+                quote! {
+                    use patch_db::ModelExt;
+                    match self.as_value()[#tag].as_str() {
                         #tag_variants_mut
                         _ => #match_name_mut::Error(&mut *self),
                     }
@@ -344,6 +555,8 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
             )
         } else {
             let mut tag_variants = TokenStream::new();
+            let mut tag_variants_unmatch = TokenStream::new();
+            let mut tag_variants_ref = TokenStream::new();
             let mut tag_variants_mut = TokenStream::new();
             for variant in &ast.variants {
                 let variant_name = &variant.ident;
@@ -356,8 +569,22 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
                         #variant_accessor.index_into_owned(v).unwrap_or_default()
                     })),
                 });
+                tag_variants_unmatch.extend(quote_spanned! { variant_name.span() =>
+                    #match_name::#variant_name(v) => Self::from_value({
+                        let mut a = v.into_value();
+                        a[#tag] = patch_db::Value::String(std::sync::Arc::new(#variant_accessor.to_owned()));
+                        a
+                    }),
+                });
+                tag_variants_ref.extend(quote_spanned! { variant_name.span() =>
+                    Some(#variant_accessor) => #match_name_ref::#variant_name(self.transmute_ref(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #variant_accessor.index_into(v).unwrap_or(&patch_db::value::NULL)
+                    })),
+                });
                 tag_variants_mut.extend(quote_spanned! { variant_name.span() =>
-                    Some(#variant_accessor) => #match_name_mut::#variant_name(self.transmute(|v| {
+                    Some(#variant_accessor) => #match_name_mut::#variant_name(self.transmute_mut(|v| {
                         #[allow(unused_imports)]
                         use patch_db::value::index::Index;
                         #variant_accessor.index_or_insert(v)
@@ -366,21 +593,39 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
             }
             (
                 quote! {
-                    match self[#tag].as_str() {
+                    use patch_db::ModelExt;
+                    match self.as_value()[#tag].as_str() {
                         #tag_variants
-                        _ => #match_name::Error(self.into_inner()),
+                        _ => #match_name::Error(self.into_value()),
                     }
                 },
                 quote! {
-                    match self[#tag].as_str() {
+                    use patch_db::ModelExt;
+                    match value {
+                        #tag_variants_unmatch
+                        #match_name::Error(v) => Self::from_value(v),
+                    }
+                },
+                quote! {
+                    use patch_db::ModelExt;
+                    match self.as_value()[#tag].as_str() {
+                        #tag_variants_ref
+                        _ => #match_name_ref::Error(self.as_value()),
+                    }
+                },
+                quote! {
+                    use patch_db::ModelExt;
+                    match self.as_value()[#tag].as_str() {
                         #tag_variants_mut
-                        _ => #match_name_mut::Error(&mut *self),
+                        _ => #match_name_mut::Error(self.as_value_mut()),
                     }
                 },
             )
         }
     } else {
         let mut tag_variants = TokenStream::new();
+        let mut tag_variants_unmatch = TokenStream::new();
+        let mut tag_variants_ref = TokenStream::new();
         let mut tag_variants_mut = TokenStream::new();
         for variant in &ast.variants {
             let variant_name = &variant.ident;
@@ -394,9 +639,25 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
                     }))
                 } else
             });
+            tag_variants_unmatch.extend(quote_spanned! { variant_name.span() =>
+                #match_name::#variant_name(v) => Self::from_value({
+                    let mut a = patch_db::value::json!({});
+                    a[#variant_accessor] = v.into_value();
+                    a
+                }),
+            });
+            tag_variants_ref.extend(quote_spanned! { variant_name.span() =>
+                if value.as_object().map(|o| o.contains_key(#variant_accessor)).unwrap_or(false) {
+                    #match_name_ref::#variant_name(self.transmute_ref(|v| {
+                        #[allow(unused_imports)]
+                        use patch_db::value::index::Index;
+                        #variant_accessor.index_into(v).unwrap_or(&patch_db::value::NULL)
+                    }))
+                } else
+            });
             tag_variants_mut.extend(quote_spanned! { variant_name.span() =>
                 if value.as_object().map(|o| o.contains_key(#variant_accessor)).unwrap_or(false) {
-                    #match_name_mut::#variant_name(self.transmute(|v| {
+                    #match_name_mut::#variant_name(self.transmute_mut(|v| {
                         #[allow(unused_imports)]
                         use patch_db::value::index::Index;
                         #variant_accessor.index_or_insert(v)
@@ -406,11 +667,26 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
         }
         (
             quote! {
+                use patch_db::ModelExt;
                 #tag_variants {
                     #match_name::Error(self.into_inner()),
                 }
             },
             quote! {
+                use patch_db::ModelExt;
+                match value {
+                    #tag_variants_unmatch
+                    #match_name::Error(v) => Self::from_value(v),
+                }
+            },
+            quote! {
+                use patch_db::ModelExt;
+                #tag_variants_ref {
+                    #match_name_ref::Error(&*self),
+                }
+            },
+            quote! {
+                use patch_db::ModelExt;
                 #tag_variants_mut {
                     #match_name_mut::Error(&mut *self),
                 }
@@ -429,22 +705,31 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
                 .into_compile_error()
             }
         };
+        let model_variant_ty = replace_self(model_ty.clone(), &ty);
         model_variants.extend(quote_spanned! { name.span() =>
-            #name(patch_db::Model<#ty>),
+            #name(#model_variant_ty),
+        });
+        ref_model_variants.extend(quote_spanned! { name.span() =>
+            #name(&'a #model_variant_ty),
         });
         mut_model_variants.extend(quote_spanned! { name.span() =>
-            #name(&'a mut patch_db::Model<#ty>),
+            #name(&'a mut #model_variant_ty),
         });
     }
     let name = &base.ident;
     let vis = &base.vis;
     quote! {
-        impl patch_db::HasModel for #name {}
+        impl patch_db::HasModel for #name {
+            type Model = #model_ty;
+        }
 
-        impl patch_db::Model<#name> {
-            #vis fn matchable(&self) -> #match_name {
+        impl #model_ty_name {
+            #vis fn into_match(self) -> #match_name {
                 #impl_new
             }
+            #vis fn from_match(value: #match_name) -> Self {
+                #impl_unmatch
+            }
         }
 
         #vis enum #match_name {
@@ -452,8 +737,19 @@ fn build_model_enum(base: &DeriveInput, ast: &DataEnum) -> TokenStream {
             Error(patch_db::Value),
         }
 
-        impl patch_db::Model<#name> {
-            #vis fn matchable<'a>(&'a self) -> #match_name_mut<'a> {
+        impl #model_ty_name {
+            #vis fn as_match<'a>(&'a self) -> #match_name_ref<'a> {
+                #impl_new_ref
+            }
+        }
+
+        #vis enum #match_name_ref<'a> {
+            #ref_model_variants
+            Error(&'a patch_db::Value),
+        }
+
+        impl #model_ty_name {
+            #vis fn as_match_mut<'a>(&'a mut self) -> #match_name_mut<'a> {
                 #impl_new_mut
             }
         }

patch-db/src/lib.rs

@@ -16,10 +16,11 @@ mod test;
 
 pub use imbl_value as value;
 pub use imbl_value::Value;
-pub use model::{HasModel, Map, Model, ModelExt};
+pub use model::{HasModel, Model, ModelExt};
 pub use patch::{DiffPatch, Dump, Revision};
 pub use patch_db_macro::HasModel;
 pub use store::{PatchDb, Store};
+use tokio::sync::TryLockError;
 pub use {json_patch, json_ptr};
 
 pub type Subscriber = tokio::sync::mpsc::UnboundedReceiver<Arc<Revision>>;
@@ -47,5 +48,7 @@ pub enum Error {
     #[error("Node Does Not Exist: {0}")]
     NodeDoesNotExist(JsonPointer),
     #[error("Provided Function Panicked! {0}")]
-    Panick(String),
+    Panic(String),
+    #[error("Would Block")]
+    WouldBlock(#[from] TryLockError),
 }

patch-db/src/model.rs

@@ -1,193 +1,179 @@
-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: Sized {
+    type Model: Model<Self>;
+}
 
-pub trait HasModel {}
+mod sealed {
+    use super::*;
+    pub trait ModelMarker {
+        fn into_value(self) -> Value;
+        fn from_value(value: Value) -> Self;
+        fn as_value<'a>(&'a self) -> &'a Value;
+        fn value_as<'a>(value: &'a Value) -> &'a Self;
+        fn as_value_mut<'a>(&'a mut self) -> &'a mut Value;
+        fn value_as_mut<'a>(value: &'a mut Value) -> &'a mut Self;
+    }
+    impl<T> ModelMarker for T
+    where
+        T: From<Value> + Into<Value> + Sized,
+        for<'a> &'a T: From<&'a Value> + Into<&'a Value>,
+        for<'a> &'a mut T: From<&'a mut Value> + Into<&'a mut Value>,
+    {
+        fn into_value(self) -> Value {
+            self.into()
+        }
+        fn from_value(value: Value) -> Self {
+            value.into()
+        }
+        fn as_value<'a>(&'a self) -> &'a Value {
+            self.into()
+        }
+        fn value_as<'a>(value: &'a Value) -> &'a Self {
+            value.into()
+        }
+        fn as_value_mut<'a>(&'a mut self) -> &'a mut Value {
+            self.into()
+        }
+        fn value_as_mut<'a>(value: &'a mut Value) -> &'a mut Self {
+            value.into()
+        }
+    }
+}
 
-/// &mut Model<T> <=> &mut Value
+pub trait Model<T>: sealed::ModelMarker + Sized {
+    type Model<U>: Model<U>;
+}
+pub trait ModelExt<T>: Model<T> {
+    fn into_value(self) -> Value {
+        <Self as sealed::ModelMarker>::into_value(self)
+    }
+    fn from_value(value: Value) -> Self {
+        <Self as sealed::ModelMarker>::from_value(value)
+    }
+    fn as_value<'a>(&'a self) -> &'a Value {
+        <Self as sealed::ModelMarker>::as_value(self)
+    }
+    fn value_as<'a>(value: &'a Value) -> &'a Self {
+        <Self as sealed::ModelMarker>::value_as(value)
+    }
+    fn as_value_mut<'a>(&'a mut self) -> &'a mut Value {
+        <Self as sealed::ModelMarker>::as_value_mut(self)
+    }
+    fn value_as_mut<'a>(value: &'a mut Value) -> &'a mut Self {
+        <Self as sealed::ModelMarker>::value_as_mut(value)
+    }
+    fn transmute<U>(self, f: impl FnOnce(Value) -> Value) -> Self::Model<U> {
+        Self::Model::<U>::from_value(f(<Self as sealed::ModelMarker>::into_value(self)))
+    }
+    fn transmute_ref<'a, U>(
+        &'a self,
+        f: impl for<'b> FnOnce(&'b Value) -> &'b Value,
+    ) -> &'a Self::Model<U> {
+        Self::Model::<U>::value_as(f(<Self as sealed::ModelMarker>::as_value(self)))
+    }
+    fn transmute_mut<'a, U>(
+        &'a mut self,
+        f: impl for<'b> FnOnce(&'b mut Value) -> &'b mut Value,
+    ) -> &'a mut Self::Model<U> {
+        Self::Model::<U>::value_as_mut(f(<Self as sealed::ModelMarker>::as_value_mut(self)))
+    }
+}
+impl<T, M: Model<T>> ModelExt<T> for M {}
 
-#[repr(transparent)]
-#[derive(Debug)]
-pub struct Model<T> {
+#[cfg(test)]
+mod test {
+    use crate as patch_db;
+    use crate::model::sealed::ModelMarker;
+    use imbl_value::{from_value, json, to_value, Value};
+    use serde::{de::DeserializeOwned, Serialize};
+    use std::marker::PhantomData;
+
+    /// &mut Model<T> <=> &mut Value
+    #[repr(transparent)]
+    #[derive(Debug)]
+    pub struct Model<T> {
         value: Value,
         phantom: PhantomData<T>,
-}
-impl<T> Clone for Model<T> {
+    }
+    impl<T: DeserializeOwned> Model<T> {
+        pub fn de(self) -> Result<T, imbl_value::Error> {
+            from_value(self.value)
+        }
+    }
+    impl<T: Serialize> Model<T> {
+        pub fn ser(&mut self, value: &T) -> Result<(), imbl_value::Error> {
+            self.value = to_value(value)?;
+            Ok(())
+        }
+    }
+    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 {
+    impl<T> From<Value> for Model<T> {
+        fn from(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,
+    impl<T> From<Model<T>> for Value {
+        fn from(value: Model<T>) -> Self {
+            value.value
         }
     }
-    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)))
+    impl<'a, T> From<&'a Value> for &'a Model<T> {
+        fn from(value: &'a Value) -> Self {
+            unsafe { std::mem::transmute(value) }
         }
     }
-}
-
-pub trait ModelExt: Deref<Target = Value> + DerefMut {
-    type T: DeserializeOwned + Serialize;
-    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())
-    }
-}
-
-impl<T: DeserializeOwned + Serialize> ModelExt for Model<T> {
-    type T = T;
-}
-
-impl<T> Model<Option<T>> {
-    pub fn transpose(self) -> Option<Model<T>> {
-        if self.is_null() {
-            None
-        } else {
-            Some(self.transmute(|a| a))
+    impl<'a, T> From<&'a Model<T>> for &'a Value {
+        fn from(value: &'a Model<T>) -> Self {
+            unsafe { std::mem::transmute(value) }
         }
     }
-}
-
-pub trait Map: DeserializeOwned + Serialize {
-    type Key;
-    type Value;
-    type Error: From<imbl_value::Error>;
-}
-
-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> From<&'a mut Value> for &mut Model<T> {
+        fn from(value: &'a mut Value) -> Self {
+            unsafe { std::mem::transmute(value) }
         }
     }
-}
-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,
+    impl<'a, T> From<&'a mut Model<T>> for &mut Value {
+        fn from(value: &'a mut Model<T>) -> Self {
+            unsafe { std::mem::transmute(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(())
+    impl<T> patch_db::Model<T> for Model<T> {
+        type Model<U> = Model<U>;
     }
-            _ => 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)]
+    #[model = "Model<Self>"]
     // #[macro_debug]
     struct Foo {
         a: Bar,
     }
 
     #[derive(crate::HasModel)]
+    #[model = "Model<Self>"]
     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();
+        a.as_b_mut().ser(&"NotThis".into()).unwrap();
+        a.as_b_mut().ser(&"Replaced".into()).unwrap();
     }
 
     #[test]
     fn test() {
-        let mut model = Model::<Foo>::new(imbl_value::json!({
+        let mut model = Model::<Foo>::from(imbl_value::json!({
             "a": {
                 "b": "ReplaceMe"
             }
@@ -195,8 +181,8 @@ mod test {
         mutate_fn(&mut model);
         mutate_fn(&mut model);
         assert_eq!(
-            &*model,
-            &imbl_value::json!({
+            model.as_value(),
+            &json!({
                 "a": {
                     "b": "Replaced"
                 }

patch-db/src/store.rs

@@ -6,6 +6,7 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 use fd_lock_rs::FdLock;
+use futures::FutureExt;
 use imbl_value::{InternedString, Value};
 use json_patch::PatchError;
 use json_ptr::{JsonPointer, SegList};
@@ -360,7 +361,7 @@ impl PatchDb {
         let mut store = self.store.write().await;
         let old = store.persistent.clone();
         let (new, res) = std::panic::catch_unwind(move || f(old)).map_err(|e| {
-            Error::Panick(
+            Error::Panic(
                 e.downcast()
                     .map(|a| *a)
                     .unwrap_or_else(|_| "UNKNOWN".to_owned()),
@@ -370,4 +371,33 @@ impl PatchDb {
         store.apply(diff).await?;
         Ok((new, res))
     }
+    pub async fn run_idempotent<F, Fut, T, E>(&self, f: F) -> Result<(Value, T), E>
+    where
+        F: Fn(Value) -> Fut + Send + Sync + UnwindSafe,
+        for<'a> &'a F: UnwindSafe,
+        Fut: std::future::Future<Output = Result<(Value, T), E>> + UnwindSafe,
+        E: From<Error>,
+    {
+        let store = self.store.read().await;
+        let old = store.persistent.clone();
+        drop(store);
+        loop {
+            let (new, res) = async { f(old.clone()).await }
+                .catch_unwind()
+                .await
+                .map_err(|e| {
+                    Error::Panic(
+                        e.downcast()
+                            .map(|a| *a)
+                            .unwrap_or_else(|_| "UNKNOWN".to_owned()),
+                    )
+                })??;
+            let mut store = self.store.write().await;
+            if &old == &store.persistent {
+                let diff = diff(&store.persistent, &new);
+                store.apply(diff).await?;
+                return Ok((new, res));
+            }
+        }
+    }
 }

patch-db/src/test.rs

@@ -1,7 +1,7 @@
 use std::future::Future;
 use std::sync::Arc;
 
-use imbl_value::Value;
+use imbl_value::{json, Value};
 use json_ptr::JsonPointer;
 use patch_db::{HasModel, PatchDb, Revision};
 use proptest::prelude::*;
@@ -15,14 +15,14 @@ async fn init_db(db_name: String) -> PatchDb {
     let db = PatchDb::open(db_name).await.unwrap();
     db.put(
         &JsonPointer::<&'static str>::default(),
-        &Sample {
-            a: "test1".to_string(),
-            b: Child {
-                a: "test2".to_string(),
-                b: 1,
-                c: NewType(None),
-            },
+        &json!({
+            "a": "test1",
+            "b": {
+                "a": "test2",
+                "b": 1,
+                "c": null,
             },
+        }),
     )
     .await
     .unwrap();
@@ -71,19 +71,19 @@ proptest! {
     }
 }
 
-#[derive(Debug, serde::Deserialize, serde::Serialize, HasModel)]
-pub struct Sample {
-    a: String,
-    #[model]
-    b: Child,
-}
+// #[derive(Debug, serde::Deserialize, serde::Serialize, HasModel)]
+// pub struct Sample {
+//     a: String,
+//     #[model]
+//     b: Child,
+// }
 
-#[derive(Debug, serde::Deserialize, serde::Serialize, HasModel)]
-pub struct Child {
-    a: String,
-    b: usize,
-    c: NewType,
-}
+// #[derive(Debug, serde::Deserialize, serde::Serialize, HasModel)]
+// pub struct Child {
+//     a: String,
+//     b: usize,
+//     c: NewType,
+// }
 
-#[derive(Debug, serde::Deserialize, serde::Serialize, HasModel)]
-pub struct NewType(Option<Box<Sample>>);
+// #[derive(Debug, serde::Deserialize, serde::Serialize, HasModel)]
+// pub struct NewType(Option<Box<Sample>>);