From 2a8df03dc636d3ee385ac35116186b12345855fb Mon Sep 17 00:00:00 2001
From: Fuwn <contact@fuwn.me>
Date: Tue, 1 Mar 2022 14:38:36 -0800
Subject: refactor(ppm): use rust generator instead of crate

---
 Cargo.toml  |   3 ---
 src/main.rs |   2 +-
 src/ppm.rs  |  82 +++++++++++++++++++++++++++++++-----------------------------
 test.gif    | Bin 0 -> 31147 bytes
 test.png    | Bin 0 -> 943 bytes
 5 files changed, 44 insertions(+), 43 deletions(-)
 create mode 100644 test.gif
 create mode 100644 test.png

diff --git a/Cargo.toml b/Cargo.toml
index d0c7b28..50bcb84 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,9 +27,6 @@ byteorder = "1.4.3"
 # Time
 chrono = "0.4.19"
 
-# Generators
-generator = "0.7.0"
-
 # Image encoding
 image = "0.24.1"
 
diff --git a/src/main.rs b/src/main.rs
index 7d10479..8541135 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,7 @@
 // Copyright (C) 2022-2022 Fuwn <contact@fuwn.me>
 // SPDX-License-Identifier: MIT
 
-#![feature(decl_macro)]
+#![feature(decl_macro, generators, generator_trait)]
 #![deny(
   warnings,
   nonstandard_style,
diff --git a/src/ppm.rs b/src/ppm.rs
index f713ff1..06f696e 100644
--- a/src/ppm.rs
+++ b/src/ppm.rs
@@ -7,6 +7,7 @@ use std::{
   collections::HashMap,
   fs,
   io::{Cursor, Read},
+  ops::Generator,
 };
 
 use byteorder::{LittleEndian, ReadBytesExt};
@@ -316,15 +317,13 @@ impl PPMParser {
     self.stream.read_uint::<LittleEndian>(1).unwrap() >> 7 & 0x1 != 0
   }
 
-  fn read_line_types(line_types: Vec<u8>) -> generator::Generator<'static, (), (usize, u8)> {
-    generator::Gn::new_scoped(move |mut s| {
+  fn read_line_types(line_types: Vec<u8>) -> impl Generator<Yield = (usize, u8), Return = ()> {
+    move || {
       for index in 0..192 {
         let line_type = line_types.get(index / 4).unwrap() >> ((index % 4) * 2) & 0x03;
-        s.yield_((index, line_type));
+        yield (index, line_type);
       }
-
-      generator::done!();
-    })
+    }
   }
 
   fn read_frame(&mut self, index: usize) -> &Vec<Vec<Vec<u8>>> {
@@ -370,29 +369,47 @@ impl PPMParser {
     for layer in 0..2 {
       let bitmap = &mut self.layers[layer];
 
-      for (line, line_type) in Self::read_line_types(line_types[layer].clone()) {
-        let mut pixel = 0;
-
-        // No data stored for this line
-        if line_type == 0 {
-          // pass;
-        } else if line_type == 1 || line_type == 2 {
-          // Compressed line
-          // If `line_type == 2`, the line starts off with all the pixels set to one
-          if line_type == 2 {
-            for i in 0..256 {
-              bitmap[line][i] = 1;
+      {
+        let mut generator = Self::read_line_types(line_types[layer].clone());
+        while let std::ops::GeneratorState::Yielded((line, line_type)) =
+          std::pin::Pin::new(&mut generator).resume(())
+        {
+          let mut pixel = 0;
+
+          // No data stored for this line
+          if line_type == 0 {
+            // pass;
+          } else if line_type == 1 || line_type == 2 {
+            // Compressed line
+            // If `line_type == 2`, the line starts off with all the pixels set to one
+            if line_type == 2 {
+              for i in 0..256 {
+                bitmap[line][i] = 1;
+              }
             }
-          }
 
-          // Unpack chunk usage
-          let mut chunk_usage = self.stream.read_u32::<byteorder::BigEndian>().unwrap();
+            // Unpack chunk usage
+            let mut chunk_usage = self.stream.read_u32::<byteorder::BigEndian>().unwrap();
+
+            // Unpack pixel chunks
+            while pixel < 256 {
+              if chunk_usage & 0x8000_0000 == 0 {
+                pixel += 8;
+              } else {
+                let chunk = self.stream.read_uint::<LittleEndian>(1).unwrap();
 
-          // Unpack pixel chunks
-          while pixel < 256 {
-            if chunk_usage & 0x8000_0000 == 0 {
-              pixel += 8;
-            } else {
+                for bit in 0..8 {
+                  bitmap[line][pixel] = (chunk >> bit & 0x1) as u8;
+                  pixel += 1;
+                }
+              }
+
+              chunk_usage <<= 1;
+            }
+          // Raw line
+          } else if line_type == 3 {
+            // Unpack pixel chunks
+            while pixel < 256 {
               let chunk = self.stream.read_uint::<LittleEndian>(1).unwrap();
 
               for bit in 0..8 {
@@ -400,19 +417,6 @@ impl PPMParser {
                 pixel += 1;
               }
             }
-
-            chunk_usage <<= 1;
-          }
-        // Raw line
-        } else if line_type == 3 {
-          // Unpack pixel chunks
-          while pixel < 256 {
-            let chunk = self.stream.read_uint::<LittleEndian>(1).unwrap();
-
-            for bit in 0..8 {
-              bitmap[line][pixel] = (chunk >> bit & 0x1) as u8;
-              pixel += 1;
-            }
           }
         }
       }
diff --git a/test.gif b/test.gif
new file mode 100644
index 0000000..6050f65
Binary files /dev/null and b/test.gif differ
diff --git a/test.png b/test.png
new file mode 100644
index 0000000..091c737
Binary files /dev/null and b/test.png differ
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