feat: require renderers to return RenderResult instead of mutating one

BREAKING CHANGE: The `render` method on `Renderer`, `HelpRequest`, and
`ProgramCollect` now returns `RenderResult` instead of taking
`&mut RenderResult`. The `r_print!` and `r_println!` macros have been
removed in favor of using `std::io::Write` directly on `RenderResult`.

6 files changed, 14 insertions, 22 deletions

diff --git a/mingling_core/src/asset/help.rs b/mingling_core/src/asset/help.rs
index ff2b3d4..b3742f2 100644
--- a/mingling_core/src/asset/help.rs
+++ b/mingling_core/src/asset/help.rs
@@ -6,5 +6,5 @@ pub trait HelpRequest {
     type Entry;
 
     /// Process the previous value and write the result into the provided [`RenderResult`](./struct.RenderResult.html)
-    fn render_help(p: Self::Entry, r: &mut RenderResult);
+    fn render_help(p: Self::Entry) -> RenderResult;
 }
diff --git a/mingling_core/src/asset/renderer.rs b/mingling_core/src/asset/renderer.rs
index 1d5a2c1..732f9b7 100644
--- a/mingling_core/src/asset/renderer.rs
+++ b/mingling_core/src/asset/renderer.rs
@@ -6,5 +6,5 @@ pub trait Renderer {
     type Previous;
 
     /// Process the previous value and write the result into the provided [`RenderResult`](./struct.RenderResult.html)
-    fn render(p: Self::Previous, r: &mut RenderResult);
+    fn render(p: Self::Previous) -> RenderResult;
 }
diff --git a/mingling_core/src/program/collection.rs b/mingling_core/src/program/collection.rs
index 044379c..cbb9363 100644
--- a/mingling_core/src/program/collection.rs
+++ b/mingling_core/src/program/collection.rs
@@ -7,7 +7,7 @@ use crate::Dispatcher;
 use crate::{AnyOutput, ChainProcess, Groupped, RenderResult};
 
 #[cfg(feature = "structural_renderer")]
-use crate::{StructuralRendererSetting, error::StructuralRendererSerializeError};
+use crate::{error::StructuralRendererSerializeError, StructuralRendererSetting};
 
 #[cfg(feature = "comp")]
 use crate::{ShellContext, Suggest};
@@ -53,10 +53,10 @@ pub trait ProgramCollect {
     fn build_empty_result() -> AnyOutput<Self::Enum>;
 
     /// Render the input [`AnyOutput`](./struct.AnyOutput.html)
-    fn render(any: AnyOutput<Self::Enum>, r: &mut RenderResult);
+    fn render(any: AnyOutput<Self::Enum>) -> RenderResult;
 
     /// Render help for Entry
-    fn render_help(any: AnyOutput<Self::Enum>, r: &mut RenderResult);
+    fn render_help(any: AnyOutput<Self::Enum>) -> RenderResult;
 
     /// Find a matching chain to continue execution based on the input [AnyOutput](./struct.AnyOutput.html), returning a new [AnyOutput](./struct.AnyOutput.html)
     #[cfg(feature = "async")]
diff --git a/mingling_core/src/program/collection/mock.rs b/mingling_core/src/program/collection/mock.rs
index 568000a..20e6658 100644
--- a/mingling_core/src/program/collection/mock.rs
+++ b/mingling_core/src/program/collection/mock.rs
@@ -7,7 +7,7 @@ use crate::Dispatcher;
 use crate::{AnyOutput, ChainProcess, Groupped, ProgramCollect, RenderResult};
 
 #[cfg(feature = "structural_renderer")]
-use crate::{StructuralRendererSetting, error::StructuralRendererSerializeError};
+use crate::{error::StructuralRendererSerializeError, StructuralRendererSetting};
 
 #[cfg(feature = "comp")]
 use crate::{ShellContext, Suggest};
@@ -59,11 +59,11 @@ impl ProgramCollect for MockProgramCollect {
         unreachable!()
     }
 
-    fn render(_any: AnyOutput<Self::Enum>, _r: &mut RenderResult) {
+    fn render(_any: AnyOutput<Self::Enum>) -> RenderResult {
         unreachable!()
     }
 
-    fn render_help(_any: AnyOutput<Self::Enum>, _r: &mut RenderResult) {
+    fn render_help(_any: AnyOutput<Self::Enum>) -> RenderResult {
         unreachable!()
     }
 
diff --git a/mingling_core/src/program/exec.rs b/mingling_core/src/program/exec.rs
index d1983ed..3224c82 100644
--- a/mingling_core/src/program/exec.rs
+++ b/mingling_core/src/program/exec.rs
@@ -461,18 +461,14 @@ pub(crate) fn handle_program_control<C: ProgramCollect<Enum = C>>(
 fn render<C: ProgramCollect<Enum = C>>(program: &Program<C>, any: AnyOutput<C>) -> RenderResult {
     #[cfg(not(feature = "structural_renderer"))]
     {
-        let mut render_result = RenderResult::default();
-        C::render(any, &mut render_result);
-        render_result
+        C::render(any)
     }
     #[cfg(feature = "structural_renderer")]
     {
         #[allow(unreachable_patterns)]
         match program.structural_renderer_name {
             super::StructuralRendererSetting::Disable => {
-                let mut render_result = RenderResult::default();
-                C::render(any, &mut render_result);
-                render_result
+                C::render(any)
             }
             _ => C::structural_render(any, &program.structural_renderer_name).unwrap(),
         }
@@ -487,18 +483,14 @@ fn render_help<C: ProgramCollect<Enum = C>>(
 ) -> RenderResult {
     #[cfg(not(feature = "structural_renderer"))]
     {
-        let mut render_result = RenderResult::default();
-        C::render_help(entry, &mut render_result);
-        render_result
+        C::render_help(entry)
     }
     #[cfg(feature = "structural_renderer")]
     {
         #[allow(unreachable_patterns)]
         match program.structural_renderer_name {
             super::StructuralRendererSetting::Disable => {
-                let mut render_result = RenderResult::default();
-                C::render_help(entry, &mut render_result);
-                render_result
+                C::render_help(entry)
             }
             _ => RenderResult::default(),
         }
diff --git a/mingling_core/src/program/hook.rs b/mingling_core/src/program/hook.rs
index 630baae..56d8e0e 100644
--- a/mingling_core/src/program/hook.rs
+++ b/mingling_core/src/program/hook.rs
@@ -718,11 +718,11 @@ mod tests {
             unreachable!()
         }
 
-        fn render(_any: crate::AnyOutput<MockHookEnum>, _r: &mut crate::RenderResult) {
+        fn render(_any: crate::AnyOutput<MockHookEnum>) -> crate::RenderResult {
             unreachable!()
         }
 
-        fn render_help(_any: crate::AnyOutput<MockHookEnum>, _r: &mut crate::RenderResult) {
+        fn render_help(_any: crate::AnyOutput<MockHookEnum>) -> crate::RenderResult {
             unreachable!()
         }