Update syn to 2.0 (#119)

Author: msrd0

influxdb_derive/Cargo.toml

@@ -16,6 +16,6 @@ repository = "https://github.com/influxdb-rs/influxdb-rust"
 proc-macro = true
 
 [dependencies]
-proc-macro2 = "1.0.9"
-quote = "1.0.3"
-syn = { version = "1.0.16", features = ["extra-traits", "full"] }
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "2.0", features = ["extra-traits", "full"] }

influxdb_derive/src/lib.rs

@@ -1,15 +1,12 @@
 use proc_macro::TokenStream;
-use proc_macro2::TokenStream as TokenStream2;
-use quote::quote;
 
 mod writeable;
+use syn::parse_macro_input;
 use writeable::expand_writeable;
 
-fn krate() -> TokenStream2 {
-    quote!(::influxdb)
-}
-
 #[proc_macro_derive(InfluxDbWriteable, attributes(influxdb))]
-pub fn derive_writeable(tokens: TokenStream) -> TokenStream {
-    expand_writeable(tokens)
+pub fn derive_writeable(input: TokenStream) -> TokenStream {
+    expand_writeable(parse_macro_input!(input))
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
 }

influxdb_derive/src/writeable.rs

@@ -1,7 +1,11 @@
-use proc_macro::TokenStream;
-use proc_macro2::{TokenStream as TokenStream2, TokenTree};
+use proc_macro2::TokenStream;
 use quote::{format_ident, quote};
-use syn::{parse_macro_input, Field, Fields, Ident, ItemStruct};
+use std::convert::TryFrom;
+use syn::{
+    parse::{Parse, ParseStream},
+    punctuated::Punctuated,
+    Data, DeriveInput, Field, Fields, Ident, Meta, Token,
+};
 
 #[derive(Debug)]
 struct WriteableField {
@@ -10,108 +14,125 @@ struct WriteableField {
     is_ignore: bool,
 }
 
-impl From<Field> for WriteableField {
-    fn from(field: Field) -> WriteableField {
-        let ident = field.ident.expect("fields without ident are not supported");
+mod kw {
+    use syn::custom_keyword;
 
-        let check_influx_aware = |attr: &syn::Attribute| -> bool {
-            attr.path
-                .segments
-                .iter()
-                .last()
-                .map(|seg| seg.ident.to_string())
-                .unwrap_or_default()
-                == "influxdb"
-        };
+    custom_keyword!(tag);
+    custom_keyword!(ignore);
+}
 
-        let check_for_attr = |token_tree, ident_cmp: &str| -> bool {
-            match token_tree {
-                TokenTree::Group(group) => group
-                    .stream()
-                    .into_iter()
-                    .next()
-                    .map(|token_tree| match token_tree {
-                        TokenTree::Ident(ident) => ident == ident_cmp,
-                        _ => false,
-                    })
-                    .unwrap(),
-                _ => false,
-            }
-        };
+enum FieldAttr {
+    Tag(kw::tag),
+    Ignore(kw::ignore),
+}
 
-        let is_ignore = field.attrs.iter().any(|attr| {
-            if !check_influx_aware(attr) {
-                return false;
-            }
+impl Parse for FieldAttr {
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        let lookahead = input.lookahead1();
+        if lookahead.peek(kw::tag) {
+            Ok(Self::Tag(input.parse()?))
+        } else if lookahead.peek(kw::ignore) {
+            Ok(Self::Ignore(input.parse()?))
+        } else {
+            Err(lookahead.error())
+        }
+    }
+}
+
+struct FieldAttrs(Punctuated<FieldAttr, Token![,]>);
+
+impl Parse for FieldAttrs {
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        Ok(Self(Punctuated::parse_terminated(input)?))
+    }
+}
 
-            attr.tokens
-                .clone()
-                .into_iter()
-                .next()
-                .map(|token_tree| check_for_attr(token_tree, "ignore"))
-                .unwrap()
-        });
+impl TryFrom<Field> for WriteableField {
+    type Error = syn::Error;
 
-        let is_tag = field.attrs.iter().any(|attr| {
-            if !check_influx_aware(attr) {
-                return false;
+    fn try_from(field: Field) -> syn::Result<WriteableField> {
+        let ident = field.ident.expect("fields without ident are not supported");
+        let mut is_tag = false;
+        let mut is_ignore = false;
+
+        for attr in field.attrs {
+            match attr.meta {
+                Meta::List(list) if list.path.is_ident("influxdb") => {
+                    for attr in syn::parse2::<FieldAttrs>(list.tokens)?.0 {
+                        match attr {
+                            FieldAttr::Tag(_) => is_tag = true,
+                            FieldAttr::Ignore(_) => is_ignore = true,
+                        }
+                    }
+                }
+                _ => {}
             }
-            attr.tokens
-                .clone()
-                .into_iter()
-                .next()
-                .map(|token_tree| check_for_attr(token_tree, "tag"))
-                .unwrap()
-        });
+        }
 
-        WriteableField {
+        Ok(WriteableField {
             ident,
             is_tag,
             is_ignore,
-        }
+        })
     }
 }
 
-pub fn expand_writeable(tokens: TokenStream) -> TokenStream {
-    let krate = super::krate();
-    let input = parse_macro_input!(tokens as ItemStruct);
+pub fn expand_writeable(input: DeriveInput) -> syn::Result<TokenStream> {
     let ident = input.ident;
-    let generics = input.generics;
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
+    let fields = match input.data {
+        Data::Struct(strukt) => strukt.fields,
+        Data::Enum(inum) => {
+            return Err(syn::Error::new(
+                inum.enum_token.span,
+                "#[derive(InfluxDbWriteable)] can only be used on structs",
+            ))
+        }
+        Data::Union(cdu) => {
+            return Err(syn::Error::new(
+                cdu.union_token.span,
+                "#[derive(InfluxDbWriteable)] can only be used on structs",
+            ))
+        }
+    };
 
     let time_field = format_ident!("time");
+    let time_field_str = time_field.to_string();
     #[allow(clippy::cmp_owned)] // that's not how idents work clippy
-    let fields: Vec<TokenStream2> = match input.fields {
+    let fields = match fields {
         Fields::Named(fields) => fields
             .named
             .into_iter()
-            .map(WriteableField::from)
-            .filter(|field| !field.is_ignore)
-            .filter(|field| field.ident.to_string() != time_field.to_string())
-            .map(|field| {
-                let ident = field.ident;
-                #[allow(clippy::match_bool)]
-                match field.is_tag {
-                    true => quote!(query.add_tag(stringify!(#ident), self.#ident)),
-                    false => quote!(query.add_field(stringify!(#ident), self.#ident)),
-                }
+            .filter_map(|f| {
+                WriteableField::try_from(f)
+                    .map(|wf| {
+                        if !wf.is_ignore && wf.ident.to_string() != time_field_str {
+                            let ident = wf.ident;
+                            Some(match wf.is_tag {
+                                true => quote!(query.add_tag(stringify!(#ident), self.#ident)),
+                                false => quote!(query.add_field(stringify!(#ident), self.#ident)),
+                            })
+                        } else {
+                            None
+                        }
+                    })
+                    .transpose()
             })
-            .collect(),
+            .collect::<syn::Result<Vec<_>>>()?,
         _ => panic!("a struct without named fields is not supported"),
     };
 
-    let output = quote! {
-        impl #generics #krate::InfluxDbWriteable for #ident #generics
-        {
-            fn into_query<I: Into<String>>(self, name : I) -> #krate::WriteQuery
-            {
-                let timestamp : #krate::Timestamp = self.#time_field.into();
+    Ok(quote! {
+        impl #impl_generics ::influxdb::InfluxDbWriteable for #ident #ty_generics #where_clause {
+            fn into_query<I: Into<String>>(self, name: I) -> ::influxdb::WriteQuery {
+                let timestamp: ::influxdb::Timestamp = self.#time_field.into();
                 let mut query = timestamp.into_query(name);
                 #(
                     query = #fields;
                 )*
                 query
             }
         }
-    };
-    output.into()
+    })
 }