Directory Restructure (#1163)

* Move tests -> testing

* Directory restructure

* Update Cargo.toml during restructure

* Update Makefile during restructure

* Fix arbitrary path

common/compare_fields_derive/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "compare_fields_derive"
+version = "0.2.0"
+authors = ["Paul Hauner <paul@paulhauner.com>"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = "1.0.18"
+quote = "1.0.4"

common/compare_fields_derive/src/lib.rs

@@ -0,0 +1,75 @@
+#![recursion_limit = "256"]
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput};
+
+fn is_slice(field: &syn::Field) -> bool {
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("compare_fields")
+            && attr.tokens.to_string().replace(" ", "") == "(as_slice)"
+    })
+}
+
+#[proc_macro_derive(CompareFields, attributes(compare_fields))]
+pub fn compare_fields_derive(input: TokenStream) -> TokenStream {
+    let item = parse_macro_input!(input as DeriveInput);
+
+    let name = &item.ident;
+    let (impl_generics, ty_generics, where_clause) = &item.generics.split_for_impl();
+
+    let struct_data = match &item.data {
+        syn::Data::Struct(s) => s,
+        _ => panic!("compare_fields_derive only supports structs."),
+    };
+
+    let mut quotes = vec![];
+
+    for field in struct_data.fields.iter() {
+        let ident_a = match &field.ident {
+            Some(ref ident) => ident,
+            _ => panic!("compare_fields_derive only supports named struct fields."),
+        };
+
+        let field_name = format!("{:}", ident_a);
+        let ident_b = ident_a.clone();
+
+        let quote = if is_slice(field) {
+            quote! {
+                comparisons.push(compare_fields::Comparison::from_slice(
+                        #field_name.to_string(),
+                        &self.#ident_a,
+                        &b.#ident_b)
+                );
+            }
+        } else {
+            quote! {
+                comparisons.push(
+                    compare_fields::Comparison::child(
+                        #field_name.to_string(),
+                        &self.#ident_a,
+                        &b.#ident_b
+                    )
+                );
+            }
+        };
+
+        quotes.push(quote);
+    }
+
+    let output = quote! {
+        impl #impl_generics compare_fields::CompareFields for #name #ty_generics #where_clause {
+            fn compare_fields(&self, b: &Self) -> Vec<compare_fields::Comparison> {
+                let mut comparisons = vec![];
+
+                #(
+                    #quotes
+                )*
+
+                comparisons
+            }
+        }
+    };
+    output.into()
+}