From d6662da7b9a56f71fcfc51bc80e925f884191903 Mon Sep 17 00:00:00 2001
From: hal8174 <henning.lindemann@pm.me>
Date: Sun, 10 Aug 2025 22:07:44 +0200
Subject: [PATCH] Add macro for parsing dictionaries

---
 ray-tracing-pbrt-scene/src/lib.rs | 88 +++++++++++++++++++++----------
 1 file changed, 60 insertions(+), 28 deletions(-)

diff --git a/ray-tracing-pbrt-scene/src/lib.rs b/ray-tracing-pbrt-scene/src/lib.rs
index 8f4b7ce..42d8b57 100644
--- a/ray-tracing-pbrt-scene/src/lib.rs
+++ b/ray-tracing-pbrt-scene/src/lib.rs
@@ -47,42 +47,74 @@ fn parse_look_at(iter: &mut Tokenizer) -> Result<Statement> {
     ))
 }
 
+macro_rules! parse_dict {
+    ($tokenizer:expr => $($name_decl:ident, $type:ty, $default:expr);+ => $($name_parsing:ident, $expr:expr, $parsing:expr);+
+    ) => {
+        {
+            $(
+                let mut $name_decl = None;
+            )+
+
+            while let Some(p) = $tokenizer.next_if(|p| p.starts_with('"')).transpose()? {
+                match p.as_str() {
+                    $(
+                        $expr => {
+                            if $name_parsing.is_none() {
+                                $name_parsing = Some($parsing);
+                            } else {
+                                return Err(miette!("dfs"))
+                            }
+                        }
+                    )+
+                    _ => {todo!()}
+                }
+            }
+
+            #[derive(Debug)]
+            struct Dict {
+                $(
+                    $name_decl: $type,
+                )+
+            }
+
+            $(
+            let $name_decl = $name_decl.unwrap_or_else(|| $default);
+            )*
+
+            Dict {
+                $($name_decl,)*
+            }
+        }
+    };
+}
+
 fn parse_shape(iter: &mut Tokenizer) -> Result<Statement> {
     let shape_type = iter.next().ok_or(miette!("unable to get shape type"))??;
 
     match shape_type.as_str() {
         "\"sphere\"" => {
-            let mut radius = 1.0;
-            let zmin = -radius;
-            let zmax = radius;
-            let phimax = 360.0;
-            let mut alpha = ShapeAlpha::None;
-
-            while let Some(p) = iter.next_if(|p| p.starts_with('"')).transpose()? {
-                match p.as_str() {
-                    "\"float radius\"" => {
-                        radius = iter.parse_parameter()?;
-                    }
-                    "\"float alpha\"" => {
-                        alpha = ShapeAlpha::Value(iter.parse_parameter()?);
-                    }
-                    "\"texture alpha\"" => {
-                        alpha = ShapeAlpha::Texture(iter.parse_parameter()?);
-                    }
-                    _ => {
-                        bail!("unknown argument {}", p)
-                    }
-                }
-            }
-
+            let t = parse_dict!(iter =>
+                radius, Float, 1.0;
+                zmin, Float, {-radius};
+                zmax, Float, {radius};
+                phimax, Float, 360.0;
+                alpha, ShapeAlpha, ShapeAlpha::None
+                =>
+                radius, "\"float radius\"", iter.parse_parameter()?;
+                zmin, "\"float zmin\"", iter.parse_parameter()?;
+                zmax, "\"float zmax\"", iter.parse_parameter()?;
+                phimax, "\"float phimax\"", iter.parse_parameter()?;
+                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
+                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
+            );
             Ok(Statement::Shape(
                 ShapeType::Sphere {
-                    radius,
-                    zmin,
-                    zmax,
-                    phimax,
+                    radius: t.radius,
+                    zmin: t.zmin,
+                    zmax: t.zmax,
+                    phimax: t.phimax,
                 },
-                alpha,
+                t.alpha,
             ))
         }
         "\"trianglemesh\"" => {