From b05cb89d948a6f12abf622a5e08d589f41a26a5a Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sun, 25 Apr 2021 15:36:03 +0200
Subject: Add support for default values

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
---
 examples/config.rs       |  2 +-
 examples/simple.rs       |  2 +-
 src/backend/dialoguer.rs | 18 +++++++++++-------
 src/value_builder.rs     |  2 +-
 tests/bool.rs            |  2 +-
 tests/common/mod.rs      |  6 +++---
 tests/struct.rs          |  2 +-
 7 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/examples/config.rs b/examples/config.rs
index 453b2e2..25610ff 100644
--- a/examples/config.rs
+++ b/examples/config.rs
@@ -22,7 +22,7 @@ impl<B: 'static + Backend> CollectionBuilder for ConfigStructBuilder<B> {
     fn build_collection(&self, value_desc: &str) -> Result<Self::Output> {
         println!("Building {}", value_desc);
 
-        let verbose = bool::builder(self.0).build_value("Be verbose?")?;
+        let verbose = bool::builder(self.0).build_value("Be verbose?", Some(&false))?;
         let values = Vec::<u8>::builder(self.0).build_collection("List of values")?;
 
         Ok(Configuration {
diff --git a/examples/simple.rs b/examples/simple.rs
index bd406c4..a9dd6c9 100644
--- a/examples/simple.rs
+++ b/examples/simple.rs
@@ -2,7 +2,7 @@ use interactive_object_builder::*;
 use interactive_object_builder::backend::dialoguer::DialoguerBackend;
 
 fn main() -> Result<()> {
-    let b = bool::builder(DialoguerBackend).build_value("Success?")?;
+    let b = bool::builder(DialoguerBackend).build_value("Success?", Some(&false))?;
 
     if b {
         println!("Success");
diff --git a/src/backend/dialoguer.rs b/src/backend/dialoguer.rs
index 564750f..53eae8d 100644
--- a/src/backend/dialoguer.rs
+++ b/src/backend/dialoguer.rs
@@ -101,11 +101,15 @@ impl<T> ValueBuilder for DialoguerValueBuilder<T>
 {
     type Output = T;
 
-    fn build_value(&self, question: &str) -> Result<Self::Output> {
-        dialoguer::Input::<T>::new()
-            .with_prompt(question)
-            .interact_text()
-            .map_err(crate::error::IOBError::from)
+    fn build_value(&self, question: &str, default: Option<&Self::Output>) -> Result<Self::Output> {
+        let mut dia = dialoguer::Input::<T>::new();
+        dia.with_prompt(question);
+
+        if let Some(def) = default {
+            dia.with_initial_text(def.to_string());
+        }
+
+        dia.interact_text().map_err(crate::error::IOBError::from)
     }
 }
 
@@ -121,7 +125,7 @@ impl<T: BuildableValue> CollectionBuilder for DialoguerOptionValueBuilder<T> {
 
         if b {
             T::builder(DialoguerBackend)
-                .build_value(value_desc)
+                .build_value(value_desc, None)
                 .map(Some)
         } else {
             Ok(None)
@@ -140,7 +144,7 @@ impl<T> CollectionBuilder for DialoguerVecBuilder<T>
         let mut buf = vec![];
 
         loop {
-            let v: T = T::builder(DialoguerBackend).build_value(value_desc)?;
+            let v: T = T::builder(DialoguerBackend).build_value(value_desc, None)?;
             buf.push(v);
 
             if !dialoguer::Input::<bool>::new().with_prompt("Another one?").interact_text()? {
diff --git a/src/value_builder.rs b/src/value_builder.rs
index d7e045b..e450843 100644
--- a/src/value_builder.rs
+++ b/src/value_builder.rs
@@ -4,6 +4,6 @@ use crate::error::Result;
 pub trait ValueBuilder {
     type Output: Sized;
 
-    fn build_value(&self, question: &str) -> Result<Self::Output>;
+    fn build_value(&self, question: &str, default: Option<&Self::Output>) -> Result<Self::Output>;
 }
 
diff --git a/tests/bool.rs b/tests/bool.rs
index 17d23e8..d08b5b0 100644
--- a/tests/bool.rs
+++ b/tests/bool.rs
@@ -5,7 +5,7 @@ use interactive_object_builder::*;
 
 #[test]
 fn test_build_value() {
-    let v = bool::builder(DummyBackend).build_value("Are you sure?").unwrap();
+    let v = bool::builder(DummyBackend).build_value("Are you sure?", Some(&false)).unwrap();
     assert!(v);
 }
 
diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index 0ab668a..7e111a5 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -75,7 +75,7 @@ pub struct BoolValBuilder;
 impl ValueBuilder for BoolValBuilder {
     type Output = bool;
 
-    fn build_value(&self, _question: &str) -> Result<Self::Output> {
+    fn build_value(&self, _question: &str, _default: Option<&Self::Output>) -> Result<Self::Output> {
         Ok(true)
     }
 }
@@ -84,7 +84,7 @@ pub struct U8ValueBuilder;
 impl ValueBuilder for U8ValueBuilder {
     type Output = u8;
 
-    fn build_value(&self, _question: &str) -> Result<Self::Output> {
+    fn build_value(&self, _question: &str, _default: Option<&Self::Output>) -> Result<Self::Output> {
         Ok(42)
     }
 }
@@ -97,7 +97,7 @@ impl<T: BuildableValue> CollectionBuilder for VecBuilder<T> {
         let mut buf = vec![];
 
         loop {
-            let v: T = T::builder(DummyBackend).build_value(value_desc)?;
+            let v: T = T::builder(DummyBackend).build_value(value_desc, None)?;
             buf.push(v);
 
             if buf.len() == 3 {
diff --git a/tests/struct.rs b/tests/struct.rs
index 9845278..3a14750 100644
--- a/tests/struct.rs
+++ b/tests/struct.rs
@@ -23,7 +23,7 @@ impl<B: 'static + Backend> CollectionBuilder for ConfigStructBuilder<B> {
     fn build_collection(&self, value_desc: &str) -> Result<Self::Output> {
         println!("Building {}", value_desc);
 
-        let verbose = bool::builder(self.0).build_value(value_desc)?;
+        let verbose = bool::builder(self.0).build_value(value_desc, None)?;
         let values = Vec::<u8>::builder(self.0).build_collection(value_desc)?;
 
         Ok(Configuration {
-- 
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