From 56c2885565bacc4e67b9d1d57d02561f2609816b Mon Sep 17 00:00:00 2001
From: Alpha Chen <alpha@kejadlen.dev>
Date: Fri, 19 Aug 2022 09:13:17 -0700
Subject: [PATCH] 14.3

---
 rust/.gitignore   |   1 +
 rust/Cargo.lock   |   7 +++
 rust/Cargo.toml   |   8 ++++
 rust/justfile     |   2 +
 rust/src/chunk.rs | 112 ++++++++++++++++++++++++++++++++++++++++++++++
 rust/src/main.rs  |   5 +++
 6 files changed, 135 insertions(+)
 create mode 100644 rust/.gitignore
 create mode 100644 rust/Cargo.lock
 create mode 100644 rust/Cargo.toml
 create mode 100644 rust/justfile
 create mode 100644 rust/src/chunk.rs
 create mode 100644 rust/src/main.rs

diff --git a/rust/.gitignore b/rust/.gitignore
new file mode 100644
index 0000000..eb5a316
--- /dev/null
+++ b/rust/.gitignore
@@ -0,0 +1 @@
+target
diff --git a/rust/Cargo.lock b/rust/Cargo.lock
new file mode 100644
index 0000000..661ac0d
--- /dev/null
+++ b/rust/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "lox"
+version = "0.1.0"
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
new file mode 100644
index 0000000..f6e02e9
--- /dev/null
+++ b/rust/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "lox"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/rust/justfile b/rust/justfile
new file mode 100644
index 0000000..cdac729
--- /dev/null
+++ b/rust/justfile
@@ -0,0 +1,2 @@
+test-watch:
+  while true; do fd .*.rs | entr -d cargo test; done
diff --git a/rust/src/chunk.rs b/rust/src/chunk.rs
new file mode 100644
index 0000000..66ff7f8
--- /dev/null
+++ b/rust/src/chunk.rs
@@ -0,0 +1,112 @@
+use std::alloc::{self, Layout};
+use std::marker::PhantomData;
+use std::ptr::{self, NonNull};
+
+pub enum OpCode {
+    Return,
+}
+
+pub struct Chunk {
+    count: usize,
+    capacity: usize,
+    code: NonNull<u8>,
+    _marker: PhantomData<u8>,
+}
+
+unsafe impl Send for Chunk {}
+unsafe impl Sync for Chunk {}
+
+impl Chunk {
+    pub fn new() -> Self {
+        Chunk {
+            count: 0,
+            capacity: 0,
+            code: NonNull::dangling(),
+            _marker: PhantomData,
+        }
+    }
+
+    // https://doc.rust-lang.org/nomicon/vec/vec-push-pop.html
+    pub fn write(&mut self, byte: u8) {
+        if self.count == self.capacity {
+            self.grow();
+        }
+
+        unsafe {
+            ptr::write(self.code.as_ptr().add(self.count), byte);
+        }
+
+        // Can't fail, we'll OOM first.
+        self.count += 1;
+    }
+
+    // https://doc.rust-lang.org/nomicon/vec/vec-alloc.html
+    fn grow(&mut self) {
+        // Crafting Interpreters: GROW_CAPACITY
+        let new_cap = if self.capacity < 8 {
+            8
+        } else {
+            // This can't overflow since self.capacity <= isize::MAX.
+            self.capacity * 2
+        };
+
+        // `Layout::array` checks that the number of bytes is <= usize::MAX,
+        // but this is redundant since old_layout.size() <= isize::MAX,
+        // so the `unwrap` should never fail.
+        let new_layout = Layout::array::<u8>(new_cap).unwrap();
+
+        // Ensure that the new allocation doesn't exceed `isize::MAX` bytes.
+        assert!(
+            new_layout.size() <= isize::MAX as usize,
+            "Allocation too large"
+        );
+
+        // Crafting Interpreters: GROW_ARRAY / reallocate
+        //   TODO: Handle shrinking maybe? We may need to
+        //         extract these out if it's used elsewhere
+        //         in the book
+        let new_ptr = if self.capacity == 0 {
+            unsafe { alloc::alloc(new_layout) }
+        } else {
+            let old_layout = Layout::array::<u8>(self.capacity).unwrap();
+            let old_ptr = self.code.as_ptr() as *mut u8;
+            unsafe { alloc::realloc(old_ptr, old_layout, new_layout.size()) }
+        };
+
+        // If allocation fails, `new_ptr` will be null, in which case we abort.
+        self.code = match NonNull::new(new_ptr as *mut u8) {
+            Some(p) => p,
+            None => alloc::handle_alloc_error(new_layout),
+        };
+        self.capacity = new_cap;
+    }
+
+    // https://doc.rust-lang.org/nomicon/vec/vec-push-pop.html
+    pub fn pop(&mut self) -> Option<u8> {
+        if self.count == 0 {
+            None
+        } else {
+            self.count -= 1;
+            unsafe { Some(ptr::read(self.code.as_ptr().add(self.count))) }
+        }
+    }
+}
+
+// https://doc.rust-lang.org/nomicon/vec/vec-dealloc.html
+impl Drop for Chunk {
+    fn drop(&mut self) {
+        if self.capacity != 0 {
+            while self.pop().is_some() {}
+            let layout = Layout::array::<u8>(self.capacity).unwrap();
+            unsafe {
+                alloc::dealloc(self.code.as_ptr() as *mut u8, layout);
+            }
+        }
+    }
+}
+
+impl Default for Chunk {
+    fn default() -> Self {
+        Self::new()
+    }
+}
diff --git a/rust/src/main.rs b/rust/src/main.rs
new file mode 100644
index 0000000..88c5d67
--- /dev/null
+++ b/rust/src/main.rs
@@ -0,0 +1,5 @@
+pub mod chunk;
+
+fn main() {
+    println!("Hello, world!");
+}