Set schema title and description from #[doc]s

Work in progress

schemars_derive/src/metadata.rs

@@ -0,0 +1,67 @@
+use crate::doc_attrs;
+use proc_macro2::TokenStream;
+use syn::Attribute;
+
+#[derive(Debug, Clone, PartialEq, Default)]
+pub struct SchemaMetadata {
+    pub title: Option<String>,
+    pub description: Option<String>,
+    pub read_only: bool,
+    pub write_only: bool,
+}
+
+pub fn set_metadata_on_schema_from_docs(
+    schema_expr: TokenStream,
+    attrs: &[Attribute],
+) -> TokenStream {
+    let metadata = get_metadata_from_docs(attrs);
+    set_metadata_on_schema(schema_expr, &metadata)
+}
+
+pub fn get_metadata_from_docs(attrs: &[Attribute]) -> SchemaMetadata {
+    let (title, description) = doc_attrs::get_title_and_desc_from_docs(attrs);
+    SchemaMetadata {
+        title,
+        description,
+        ..Default::default()
+    }
+}
+
+pub fn set_metadata_on_schema(schema_expr: TokenStream, metadata: &SchemaMetadata) -> TokenStream {
+    let mut setters = Vec::<TokenStream>::new();
+
+    if let Some(title) = &metadata.title {
+        setters.push(quote! {
+            metadata.title = Some(#title.to_owned());
+        })
+    }
+    if let Some(description) = &metadata.description {
+        setters.push(quote! {
+            metadata.description = Some(#description.to_owned());
+        })
+    }
+    if metadata.read_only {
+        setters.push(quote! {
+            metadata.read_only = true;
+        })
+    }
+    if metadata.write_only {
+        setters.push(quote! {
+            metadata.write_only = true;
+        })
+    }
+
+    if setters.is_empty() {
+        return schema_expr;
+    }
+
+    quote! {
+        {
+            let schema = #schema_expr.into();
+            let mut schema_obj = gen.objectify(schema);
+            let mut metadata = schema_obj.metadata();
+            #(#setters)*
+            schemars::schema::Schema::Object(schema_obj)
+        }
+    }
+}