From 6e1effab94e018c85762810b5a93b760f3302dc0 Mon Sep 17 00:00:00 2001
From: Alexander Polakov <plhk@sdf.org>
Date: Wed, 25 Jul 2018 01:53:09 +0300
Subject: [PATCH] Doc comments first try

---
 magnet_derive/src/codegen_enum.rs  |  5 +++++
 magnet_derive/src/codegen_field.rs | 27 +++++++++++++++++++--------
 magnet_derive/src/meta.rs          | 15 +++++++++++++++
 magnet_schema/src/support.rs       |  8 ++++++++
 4 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/magnet_derive/src/codegen_enum.rs b/magnet_derive/src/codegen_enum.rs
index f4e6a1e..d50659c 100644
--- a/magnet_derive/src/codegen_enum.rs
+++ b/magnet_derive/src/codegen_enum.rs
@@ -16,6 +16,10 @@ pub fn impl_bson_schema_enum(attrs: Vec<Attribute>, ast: DataEnum) -> Result<Tok
         Some(s) => Some(meta_value_as_str(&s)?.parse()?),
         None => None,
     };
+    let doc = doc_meta(&attrs).and_then(|doc| meta_value_as_str(&doc).ok());
+    let doc = quote! {
+        "description": #doc
+    };
     let tagging = SerdeEnumTag::from_attrs(&attrs)?;
 
     let variants: Vec<_> = ast.variants
@@ -25,6 +29,7 @@ pub fn impl_bson_schema_enum(attrs: Vec<Attribute>, ast: DataEnum) -> Result<Tok
 
     let tokens = quote! {
         doc! {
+            #doc,
             "anyOf": [ #(#variants,)* ]
         }
     };
diff --git a/magnet_derive/src/codegen_field.rs b/magnet_derive/src/codegen_field.rs
index 7119e72..14dd245 100644
--- a/magnet_derive/src/codegen_field.rs
+++ b/magnet_derive/src/codegen_field.rs
@@ -34,7 +34,7 @@ pub fn impl_bson_schema_fields_extra(
             impl_bson_schema_named_fields(attrs, fields.named, extra)
         },
         Fields::Unnamed(fields) => {
-            impl_bson_schema_indexed_fields(fields.unnamed, extra)
+            impl_bson_schema_indexed_fields(attrs, fields.unnamed, extra)
         },
         Fields::Unit => {
             assert!(extra.is_none(), "internally-tagged unit should've been handled");
@@ -51,10 +51,17 @@ fn impl_bson_schema_named_fields(
 ) -> Result<TokenStream> {
     let properties = &field_names(attrs, &fields)?;
     let defs: Vec<_> = fields.iter().map(field_def).collect::<Result<_>>()?;
+    let doc = doc_meta(&attrs).and_then(|doc| meta_value_as_str(&doc).ok());
+    let doc = if doc.is_some() {
+        quote! { "description": #doc.trim_left(), }
+    } else {
+        quote! {}
+    };
     let tokens = if let Some(TagExtra { tag, variant }) = extra {
         quote! {
             doc! {
                 "type": "object",
+                #doc
                 "additionalProperties": false,
                 "required": [ #tag, #(#properties,)* ],
                 "properties": {
@@ -67,6 +74,7 @@ fn impl_bson_schema_named_fields(
         quote! {
             doc! {
                 "type": "object",
+                #doc
                 "additionalProperties": false,
                 "required": [ #(#properties,)* ],
                 "properties": {
@@ -90,15 +98,17 @@ fn field_def(field: &Field) -> Result<TokenStream> {
     let max_excl = magnet_meta_name_value(&field.attrs, "max_excl")?;
     let lower = bounds_from_meta(min_incl, min_excl)?;
     let upper = bounds_from_meta(max_incl, max_excl)?;
+    let doc = doc_meta(&field.attrs).and_then(|doc| meta_value_as_str(&doc).ok()).unwrap_or_else(String::new);
 
     Ok(quote! {
-        ::magnet_schema::support::extend_schema_with_bounds(
-            <#ty as ::magnet_schema::BsonSchema>::bson_schema(),
-            ::magnet_schema::support::Bounds {
-                lower: #lower,
-                upper: #upper,
-            },
-        )
+        ::magnet_schema::support::extend_schema_with_doc(
+            ::magnet_schema::support::extend_schema_with_bounds(
+                <#ty as ::magnet_schema::BsonSchema>::bson_schema(),
+                ::magnet_schema::support::Bounds {
+                    lower: #lower,
+                    upper: #upper,
+                },
+            ), #doc)
     })
 }
 
@@ -163,6 +173,7 @@ fn field_names(attrs: &[Attribute], fields: &Punctuated<Field, Comma>) -> Result
 /// Implements `BsonSchema` for a tuple `struct` or variant,
 /// with unnamed (numbered/indexed) fields.
 fn impl_bson_schema_indexed_fields(
+    attrs: &[Attribute],
     mut fields: Punctuated<Field, Comma>,
     extra: Option<TagExtra>,
 ) -> Result<TokenStream> {
diff --git a/magnet_derive/src/meta.rs b/magnet_derive/src/meta.rs
index bea8e73..be2fc74 100644
--- a/magnet_derive/src/meta.rs
+++ b/magnet_derive/src/meta.rs
@@ -4,6 +4,21 @@ use std::f64;
 use syn::{ Attribute, Meta, NestedMeta, MetaNameValue, Lit };
 use error::{ Error, Result };
 
+pub fn doc_meta(attrs: &[Attribute]) -> Option<MetaNameValue> {
+    let mut value = attrs.iter().filter_map(|attr| {
+        if let Some(meta) = attr.interpret_meta() {
+            match meta {
+                Meta::NameValue(ref val) if val.ident == "doc" => {
+                    return Some(val.clone())
+                }
+                _ => {},
+            };
+        }
+        None
+    });
+    value.next()
+}
+
 /// Returns the inner, `...` part of the first `#[name(...)]` attribute
 /// with the specified name (like `#[magnet(key ( = "value")?)]`).
 /// TODO(H2CO3): check for duplicate arguments and bail out with an error
diff --git a/magnet_schema/src/support.rs b/magnet_schema/src/support.rs
index 3016048..987cc0a 100644
--- a/magnet_schema/src/support.rs
+++ b/magnet_schema/src/support.rs
@@ -56,6 +56,14 @@ pub fn extend_schema_with_bounds(mut schema: Document, bounds: Bounds) -> Docume
     schema
 }
 
+#[doc(hidden)]
+pub fn extend_schema_with_doc(mut schema: Document, doc: &str) -> Document {
+    if !doc.is_empty() {
+        schema.insert("description", doc.trim_left());
+    }
+    schema
+}
+
 /// This function should not be used directly; calls to it are only generated by
 /// `magnet_derive` when emitting code for internally-tagged newtype variants.
 ///