From 9f02a9ca09f90082a9e0f8f2c52a331967db76a5 Mon Sep 17 00:00:00 2001
From: Alex Orlenko <zxteam@protonmail.com>
Date: Tue, 17 Aug 2021 15:17:03 +0100
Subject: [PATCH] Add `Debug::event()` to the hook's Debug structure

---
 src/hook.rs    | 29 +++++++++++++++++++++++++++++
 src/lib.rs     |  2 +-
 tests/hooks.rs |  7 +++++--
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/hook.rs b/src/hook.rs
index 3004e42..e65c088 100644
--- a/src/hook.rs
+++ b/src/hook.rs
@@ -23,6 +23,25 @@ pub struct Debug<'a> {
 }
 
 impl<'a> Debug<'a> {
+    /// Returns the specific event that triggered the hook.
+    ///
+    /// For [Lua 5.1] `DebugEvent::TailCall` is used for return events to indicate a return
+    /// from a function that did a tail call.
+    ///
+    /// [Lua 5.1]: https://www.lua.org/manual/5.1/manual.html#pdf-LUA_HOOKTAILRET
+    pub fn event(&self) -> DebugEvent {
+        unsafe {
+            match (&*self.ar).event {
+                ffi::LUA_HOOKCALL => DebugEvent::Call,
+                ffi::LUA_HOOKRET => DebugEvent::Ret,
+                ffi::LUA_HOOKTAILCALL => DebugEvent::TailCall,
+                ffi::LUA_HOOKLINE => DebugEvent::Line,
+                ffi::LUA_HOOKCOUNT => DebugEvent::Count,
+                event => mlua_panic!("Unknown Lua event code: {}", event),
+            }
+        }
+    }
+
     /// Corresponds to the `n` what mask.
     pub fn names(&self) -> DebugNames<'a> {
         unsafe {
@@ -95,6 +114,16 @@ impl<'a> Debug<'a> {
     }
 }
 
+/// Represents a specific event that triggered the hook.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum DebugEvent {
+    Call,
+    Ret,
+    TailCall,
+    Line,
+    Count,
+}
+
 #[derive(Clone, Debug)]
 pub struct DebugNames<'a> {
     pub name: Option<&'a [u8]>,
diff --git a/src/lib.rs b/src/lib.rs
index e4cb790..afbb456 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -102,7 +102,7 @@ pub use crate::{ffi::lua_CFunction, ffi::lua_State};
 
 pub use crate::error::{Error, ExternalError, ExternalResult, Result};
 pub use crate::function::Function;
-pub use crate::hook::{Debug, DebugNames, DebugSource, DebugStack, HookTriggers};
+pub use crate::hook::{Debug, DebugEvent, DebugNames, DebugSource, DebugStack, HookTriggers};
 pub use crate::lua::{AsChunk, Chunk, ChunkMode, GCMode, Lua, LuaOptions};
 pub use crate::multi::Variadic;
 pub use crate::scope::Scope;
diff --git a/tests/hooks.rs b/tests/hooks.rs
index 378c134..73a8888 100644
--- a/tests/hooks.rs
+++ b/tests/hooks.rs
@@ -3,7 +3,7 @@ use std::ops::Deref;
 use std::str;
 use std::sync::{Arc, Mutex};
 
-use mlua::{Error, HookTriggers, Lua, Result, Value};
+use mlua::{DebugEvent, Error, HookTriggers, Lua, Result, Value};
 
 #[test]
 fn test_line_counts() -> Result<()> {
@@ -17,6 +17,7 @@ fn test_line_counts() -> Result<()> {
             ..Default::default()
         },
         move |_lua, debug| {
+            assert_eq!(debug.event(), DebugEvent::Line);
             hook_output.lock().unwrap().push(debug.curr_line());
             Ok(())
         },
@@ -54,6 +55,7 @@ fn test_function_calls() -> Result<()> {
             ..Default::default()
         },
         move |_lua, debug| {
+            assert_eq!(debug.event(), DebugEvent::Call);
             let names = debug.names();
             let source = debug.source();
             let name = names.name.map(|s| str::from_utf8(s).unwrap().to_owned());
@@ -139,7 +141,8 @@ fn test_limit_execution_instructions() -> Result<()> {
             every_nth_instruction: Some(30),
             ..Default::default()
         },
-        move |_lua, _debug| {
+        move |_lua, debug| {
+            assert_eq!(debug.event(), DebugEvent::Count);
             max_instructions -= 30;
             if max_instructions < 0 {
                 Err(Error::RuntimeError("time's up".to_string()))