From d2c13e6f22bb5a116f189c348213e2a45e439df6 Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sat, 24 Apr 2021 12:57:12 +0200
Subject: Add support for Option<T>

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
---
 src/backend/dialoguer.rs | 26 +++++++++++++++++++++++++-
 src/backend/mod.rs       |  7 ++++---
 src/buildable.rs         | 16 +++++++++++++---
 src/lib.rs               |  7 +++++++
 4 files changed, 49 insertions(+), 7 deletions(-)

diff --git a/src/backend/dialoguer.rs b/src/backend/dialoguer.rs
index 11d5349..5bdebd6 100644
--- a/src/backend/dialoguer.rs
+++ b/src/backend/dialoguer.rs
@@ -1,7 +1,7 @@
 use crate::Backend;
-use crate::ValueBuilder;
 use crate::BuildableValue;
 use crate::CollectionBuilder;
+use crate::ValueBuilder;
 
 pub struct DialoguerBackend;
 
@@ -88,6 +88,9 @@ impl Backend for DialoguerBackend {
         Box::new(DialoguerVecBuilder::<T>(std::marker::PhantomData))
     }
 
+    fn option_builder<T: 'static + BuildableValue>(&self) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = Self::Error>> {
+        Box::new(DialoguerOptionValueBuilder::<T>(std::marker::PhantomData))
+    }
 }
 
 pub struct DialoguerValueBuilder<T: Sized>(std::marker::PhantomData<T>);
@@ -106,6 +109,27 @@ impl<T> ValueBuilder for DialoguerValueBuilder<T>
     }
 }
 
+pub struct DialoguerOptionValueBuilder<T: BuildableValue>(std::marker::PhantomData<T>);
+impl<T: BuildableValue> CollectionBuilder for DialoguerOptionValueBuilder<T> {
+    type Output = Option<T>;
+    type Error = DialoguerBackendError;
+
+    fn build_collection(&self, value_desc: &str) -> Result<Self::Output, Self::Error> {
+        let q = format!("Do you want to provide a Value for {}", value_desc);
+        let b = dialoguer::Input::<bool>::new()
+            .with_prompt(q)
+            .interact_text()?;
+
+        if b {
+            T::builder(DialoguerBackend)
+                .build_value(value_desc)
+                .map(Some)
+        } else {
+            Ok(None)
+        }
+    }
+}
+
 
 pub struct DialoguerVecBuilder<T: 'static + BuildableValue>(std::marker::PhantomData<T>);
 impl<T> CollectionBuilder for DialoguerVecBuilder<T>
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 1353a6d..3f72d66 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -1,8 +1,8 @@
 pub mod dialoguer;
 
-use crate::ValueBuilder;
 use crate::BuildableValue;
 use crate::CollectionBuilder;
+use crate::ValueBuilder;
 
 /// A backend can be used to get builders for specific types
 pub trait Backend {
@@ -26,9 +26,10 @@ pub trait Backend {
     fn char_builder(&self)   -> Box<dyn ValueBuilder<Output = char, Error = Self::Error>>;
     fn string_builder(&self) -> Box<dyn ValueBuilder<Output = String, Error = Self::Error>>;
 
+    fn option_builder<T: 'static + BuildableValue>(&self) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = Self::Error>>;
+
     fn vec_builder<T>(&self) -> Box<dyn CollectionBuilder<Output = Vec<T>, Error = Self::Error>>
-        where T: 'static + BuildableValue
-            ;
+        where T: 'static + BuildableValue;
 }
 
 
diff --git a/src/buildable.rs b/src/buildable.rs
index 95382e7..37bfc3c 100644
--- a/src/buildable.rs
+++ b/src/buildable.rs
@@ -1,6 +1,6 @@
-use crate::ValueBuilder;
-use crate::CollectionBuilder;
 use crate::Backend;
+use crate::CollectionBuilder;
+use crate::ValueBuilder;
 
 // A value that can be built interactively, using a Backend
 pub trait BuildableValue: Sized {
@@ -164,7 +164,6 @@ impl BuildableValue for String {
 }
 
 
-
 pub trait BuildableCollection {
     fn builder<E, B>(backend: B) -> Box<dyn CollectionBuilder<Output = Self, Error = E>>
         where E: Sized,
@@ -183,3 +182,14 @@ impl<T> BuildableCollection for Vec<T>
     }
 }
 
+impl<T> BuildableCollection for Option<T>
+    where T: 'static + BuildableValue + Sized
+{
+    fn builder<E, B>(backend: B) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = E>>
+        where E: Sized,
+              B: Backend<Error = E>
+    {
+        backend.option_builder()
+    }
+}
+
diff --git a/src/lib.rs b/src/lib.rs
index 21d5ab4..f7ef93b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -71,6 +71,10 @@ mod dummy_bool_test {
             unimplemented!()
         }
 
+        fn option_builder<T: 'static + BuildableValue>(&self) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = Self::Error>> {
+            unimplemented!()
+        }
+
         fn vec_builder<T>(&self) -> Box<dyn CollectionBuilder<Output = Vec<T>, Error = Self::Error>>
             where T: 'static + BuildableValue
         {
@@ -155,6 +159,9 @@ mod vec_test {
         fn string_builder(&self) -> Box<dyn ValueBuilder<Output = String, Error = Self::Error>> {
             unimplemented!()
         }
+        fn option_builder<T: 'static + BuildableValue>(&self) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = Self::Error>> {
+            unimplemented!()
+        }
         fn vec_builder<T>(&self) -> Box<dyn CollectionBuilder<Output = Vec<T>, Error = Self::Error>>
             where T: 'static + BuildableValue
         {
-- 
cgit v1.2.3


From ddaa455a66bb33299ea67e744f95c92b23715f32 Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sat, 24 Apr 2021 13:34:01 +0200
Subject: Add example for Option<bool> and Option<u64>

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
---
 examples/option.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 examples/option.rs

diff --git a/examples/option.rs b/examples/option.rs
new file mode 100644
index 0000000..937733a
--- /dev/null
+++ b/examples/option.rs
@@ -0,0 +1,15 @@
+use interactive_object_builder::*;
+use interactive_object_builder::backend::dialoguer::DialoguerBackend;
+
+fn main() -> Result<(), ()> {
+    let v = Option::<bool>::builder(DialoguerBackend).build_collection("optional yes/no")
+        .map_err(|_| ())?;
+
+    println!("{:?}", v);
+
+    let v = Option::<u64>::builder(DialoguerBackend).build_collection("optional u64")
+        .map_err(|_| ())?;
+
+    println!("{:?}", v);
+    Ok(())
+}
-- 
cgit v1.2.3