From 69a3335f1b79b074a0e1038bdfd9aa79508131d1 Mon Sep 17 00:00:00 2001
From: Martin Fischer <martin@push-f.com>
Date: Mon, 22 Nov 2021 10:06:35 +0100
Subject: refactor: support IntoIterMapCollect with N types

---
 src/lib.rs             | 16 ++++++++--------
 src/parse_trait_sig.rs |  3 +--
 src/transform.rs       | 14 +++++++-------
 3 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 3b4aeeb..caaf774 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -411,14 +411,14 @@ impl TypeTransform {
                     quote! {#arg.map_err(|x| #err_inner)}
                 }
             }
-            TypeTransform::CollectionOneType(type1) => {
-                let type1 = type1.convert(quote!(v1));
-                quote! {#arg.into_iter().map(|v1| #type1).collect()}
-            }
-            TypeTransform::CollectionTwoTypes(type1, type2) => {
-                let type1 = type1.convert(quote!(v1));
-                let type2 = type2.convert(quote!(v2));
-                quote! {#arg.into_iter().map(|(v1,v2)| (#type1, #type2)).collect()}
+            TypeTransform::IntoIterMapCollect(types) => {
+                let idents = (0..types.len()).map(|i| format_ident!("v{}", i));
+                // FUTURE: let transforms = std::iter::zip(idents, types).map(|(i, t)| t.convert(quote! {#i}));
+                let transforms = types.iter().enumerate().map(|(idx, t)| {
+                    let id = format_ident!("v{}", idx);
+                    t.convert(quote! {#id})
+                });
+                quote! {#arg.into_iter().map(|(#(#idents),*)| (#(#transforms),*)).collect()}
             }
             TypeTransform::NoOp => arg,
         }
diff --git a/src/parse_trait_sig.rs b/src/parse_trait_sig.rs
index be8cccb..29b3205 100644
--- a/src/parse_trait_sig.rs
+++ b/src/parse_trait_sig.rs
@@ -17,8 +17,7 @@ pub enum TypeTransform {
     Into,
     Box(BoxType),
     Map(Box<TypeTransform>),
-    CollectionOneType(Box<TypeTransform>),
-    CollectionTwoTypes(Box<TypeTransform>, Box<TypeTransform>),
+    IntoIterMapCollect(Vec<TypeTransform>),
     Iterator(BoxType, Box<TypeTransform>),
     Result(Box<TypeTransform>, Box<TypeTransform>),
 }
diff --git a/src/transform.rs b/src/transform.rs
index fa7877e..f2744cf 100644
--- a/src/transform.rs
+++ b/src/transform.rs
@@ -120,9 +120,9 @@ impl TypeConverter<'_> {
                                 } else if self.known_as_collection_with_one_type(&last_seg.ident)
                                     && path_len == 1
                                 {
-                                    return Ok(TypeTransform::CollectionOneType(
-                                        self.convert_type(arg)?.into(),
-                                    ));
+                                    return Ok(TypeTransform::IntoIterMapCollect(vec![
+                                        self.convert_type(arg)?
+                                    ]));
                                 }
                             }
                         }
@@ -140,10 +140,10 @@ impl TypeConverter<'_> {
                                         self.convert_type(arg2)?.into(),
                                     ));
                                 } else if self.known_as_collection_with_two_types(&last_seg.ident) {
-                                    return Ok(TypeTransform::CollectionTwoTypes(
-                                        self.convert_type(arg1)?.into(),
-                                        self.convert_type(arg2)?.into(),
-                                    ));
+                                    return Ok(TypeTransform::IntoIterMapCollect(vec![
+                                        self.convert_type(arg1)?,
+                                        self.convert_type(arg2)?,
+                                    ]));
                                 }
                             }
                         }
-- 
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