Add FromSql lifetime support

Author: vorot93

Cargo.toml

@@ -13,8 +13,9 @@ proc-macro = true
 test = false
 
 [dependencies]
+proc-macro2 = "0.3"
 syn = "0.13"
 quote = "0.5"
 
 [dev-dependencies]
-postgres = "0.15.1"
+postgres = { git = "https://github.com/sfackler/rust-postgres" }

src/accepts.rs

@@ -1,5 +1,5 @@
 use std::iter;
-use syn::Ident;
+use syn::{Ident, Lifetime};
 use quote::Tokens;
 
 use enums::Variant;
@@ -34,13 +34,17 @@ pub fn enum_body(name: &str, variants: &[Variant]) -> Tokens {
     }
 }
 
-pub fn composite_body(name: &str, trait_: &str, fields: &[Field]) -> Tokens {
+pub fn composite_body(name: &str, trait_: &str, lifetime: Option<Lifetime>, fields: &[Field]) -> Tokens {
     let num_fields = fields.len();
     let trait_ = Ident::from(trait_);
-    let traits = iter::repeat(&trait_);
     let field_names = fields.iter().map(|f| &f.name);
     let field_types = fields.iter().map(|f| &f.type_);
 
+    let trait_tokens = iter::repeat(match lifetime {
+        Some(lifetime) => quote!{ ::postgres::types::#trait_<#lifetime> },
+        None => quote! { ::postgres::types::#trait_ },
+    });
+
     quote! {
         if type_.name() != #name {
             return false;
@@ -56,7 +60,7 @@ pub fn composite_body(name: &str, trait_: &str, fields: &[Field]) -> Tokens {
                     match f.name() {
                         #(
                             #field_names => {
-                                <#field_types as ::postgres::types::#traits>::accepts(f.type_())
+                                <#field_types as #trait_tokens>::accepts(f.type_())
                             }
                         )*
                         _ => false,

src/fromsql.rs

@@ -1,5 +1,6 @@
+use proc_macro2::Span;
 use std::iter;
-use syn::{self, Ident, DeriveInput, Data, DataStruct, Fields};
+use syn::{self, Ident, DeriveInput, Data, DataStruct, Fields, Lifetime};
 use quote::Tokens;
 
 use accepts;
@@ -12,6 +13,8 @@ pub fn expand_derive_fromsql(input: DeriveInput) -> Result<Tokens, String> {
 
     let name = overrides.name.unwrap_or_else(|| input.ident.to_string());
 
+    let trait_lifetime = Lifetime::new("'from_sql", Span::call_site());
+
     let (accepts_body, to_sql_body) = match input.data {
         Data::Enum(ref data) => {
             let variants = data.variants.iter().map(Variant::parse).collect::<Result<Vec<_>, _>>()?;
@@ -23,18 +26,18 @@ pub fn expand_derive_fromsql(input: DeriveInput) -> Result<Tokens, String> {
         }
         Data::Struct(DataStruct { fields: Fields::Named(ref fields), .. }) => {
             let fields = fields.named.iter().map(Field::parse).collect::<Result<Vec<_>, _>>()?;
-            (accepts::composite_body(&name, "FromSql", &fields),
-             composite_body(&input.ident, &fields))
+            (accepts::composite_body(&name, "FromSql", Some(trait_lifetime), &fields),
+             composite_body(&input.ident, trait_lifetime, &fields))
         }
         _ => {
-            return Err("#[derive(ToSql)] may only be applied to structs, single field tuple \
+            return Err("#[derive(FromSql)] may only be applied to structs, single field tuple \
                         structs, and enums".to_owned())
         }
     };
 
     let ident = &input.ident;
     let out = quote! {
-        impl ::postgres::types::FromSql for #ident {
+        impl<#trait_lifetime> ::postgres::types::FromSql<#trait_lifetime> for #ident {
             fn from_sql(_type: &::postgres::types::Type,
                         buf: &[u8])
                         -> ::std::result::Result<#ident,
@@ -85,7 +88,7 @@ fn domain_body(ident: &Ident, field: &syn::Field) -> Tokens {
     }
 }
 
-fn composite_body(ident: &Ident, fields: &[Field]) -> Tokens {
+fn composite_body(ident: &Ident, lifetime: syn::Lifetime, fields: &[Field]) -> Tokens {
     let temp_vars = &fields.iter().map(|f| Ident::from(format!("__{}", f.ident))).collect::<Vec<_>>();
     let field_names = &fields.iter().map(|f| &f.name).collect::<Vec<_>>();
     let field_idents = &fields.iter().map(|f| &f.ident).collect::<Vec<_>>();
@@ -101,13 +104,13 @@ fn composite_body(ident: &Ident, fields: &[Field]) -> Tokens {
             ::std::result::Result::Ok(num)
         }
 
-        fn read_value<T>(type_: &::postgres::types::Type,
-                         buf: &mut &[u8])
+        fn read_value<#lifetime, T>(type_: &::postgres::types::Type,
+                         buf: &#lifetime mut &[u8])
                          -> ::std::result::Result<T,
                              ::std::boxed::Box<::std::error::Error +
                              ::std::marker::Sync +
                              ::std::marker::Send>>
-                         where T: ::postgres::types::FromSql
+                         where T: ::postgres::types::FromSql<#lifetime>
         {
             let len = read_be_i32(buf)?;
             let value = if len < 0 {

src/lib.rs

@@ -1,6 +1,7 @@
 #![recursion_limit = "256"]
 
 extern crate proc_macro;
+extern crate proc_macro2;
 extern crate syn;
 #[macro_use]
 extern crate quote;

src/tosql.rs

@@ -23,7 +23,7 @@ pub fn expand_derive_tosql(input: DeriveInput) -> Result<Tokens, String> {
         }
         Data::Struct(DataStruct { fields: Fields::Named(ref fields), .. }) => {
             let fields = fields.named.iter().map(Field::parse).collect::<Result<Vec<_>, _>>()?;
-            (accepts::composite_body(&name, "ToSql", &fields),
+            (accepts::composite_body(&name, "ToSql", None, &fields),
              composite_body(&fields))
         }
         _ => {

tests/util/mod.rs

@@ -1,10 +1,10 @@
-use postgres::types::{FromSql, ToSql};
+use postgres::types::{FromSqlOwned, ToSql};
 use postgres::Connection;
 use std::fmt;
 
 pub fn test_type<T, S>(conn: &Connection, sql_type: &str, checks: &[(T, S)])
 where
-    T: PartialEq + FromSql + ToSql,
+    T: PartialEq + FromSqlOwned + ToSql,
     S: fmt::Display,
 {
     for &(ref val, ref repr) in checks.iter() {