Add support for lua.equal()

Author: thsackos

README.md

@@ -79,7 +79,7 @@ lua.doString(
 
 | API | Support |
 |---|---|
-| Lua C API (`lua_*`) | 47.8% available (44/92) | <!-- 47.82% - Add 1.07 per -->
+| Lua C API (`lua_*`) | 48.87% available (45/92) | <!-- 47.82% - Add 1.07 per -->
 | Auxilary Library (`luaL_*`) | 6% available (3/48) | <!-- Always 2% * n, for n up to 48 -->
 | LuaJIT Extensions | *No plans to implement.* |
 
@@ -104,7 +104,7 @@ pattern has changed, such as using the Zig `init()` function pattern instead of
 | `lua_cpcall`||
 | `lua_createtable`|☑️ `lua.createTable()` |
 | `lua_dump`||
-| `lua_equal`||
+| `lua_equal`|☑️ `lua.equal()` |
 | `lua_error`||
 | `lua_gc`||
 | `lua_getallocf`|➖ `lua.getAllocF()` |

src/lua_api.zig

@@ -55,15 +55,6 @@ pub fn cpCall(lua: *Lua, func: CFn, userdata: ?*anyopaque) LuaError;
 /// Stack Behavior: `[-0, +0, m]`
 pub fn dump(lua: *Lua, writer: LuaWriter, data: *anyopaque) i32;
 
-/// Returns whether the two values in acceptable indices index1 and index2 are equal, 
-/// following the semantics of the Lua == operator (which may call metamethods). 
-/// Returns false if any of the indices is not valid.
-///
-/// From: `int lua_equal(lua_State *L, int index1, int index2);`
-/// Refer to: https://www.lua.org/manual/5.1/manual.html#lua_equal
-/// Stack Behavior: `[-0, +0, e]`
-pub fn equal(lua: *Lua, index1: i32, index2: i32) bool;
-
 /// Generates a Lua error. The error message (which can actually be a Lua value of any type)
 /// must be on the stack top. This function does a long jump and therefore never returns.
 ///

src/root.zig

@@ -879,6 +879,16 @@ pub const Lua = opaque {
         return c.lua_insert(asState(lua), index);
     }
 
+    /// Returns whether the two values in acceptable are equal, following the semantics of the Lua == operator
+    /// (which may call metamethods). Returns false if any of the indices is not valid.
+    ///
+    /// From: `int lua_equal(lua_State *L, int index1, int index2);`
+    /// Refer to: https://www.lua.org/manual/5.1/manual.html#lua_equal
+    /// Stack Behavior: `[-0, +0, e]`
+    pub fn equal(lua: *Lua, index_left: i32, index_right: i32) bool {
+        return 1 == c.lua_equal(asState(lua), index_left, index_right);
+    }
+
     /// Returns the current status of the thread. The status will be `Status.ok` for a normal thread, an error
     /// code if the thread finished its execution with an error, or `status.yield` if the thread is suspended.
     ///
@@ -1761,3 +1771,46 @@ test "doString should do the string" {
     try std.testing.expectEqualSlices(u8, "Hello, world!", actual);
     lua.pop(1);
 }
+
+test "equal should follow expected semantics" {
+    const lua = try Lua.init(std.testing.allocator);
+    defer lua.deinit();
+
+    lua.pushLString("Hello, world!");
+    lua.pushLString("hello, world!");
+    try std.testing.expect(!lua.equal(-2, -1));
+
+    lua.pop(1);
+    lua.pushLString("Hello, world!");
+    try std.testing.expect(lua.equal(-2, -1));
+
+    lua.pop(2);
+    lua.pushNumber(13.0);
+    lua.pushInteger(13);
+    try std.testing.expect(lua.equal(-2, -1));
+
+    lua.pop(2);
+    lua.pushNumber(13.5);
+    lua.pushNumber(13.4);
+    try std.testing.expect(!lua.equal(-2, -1));
+
+    lua.pop(2);
+    lua.pushNil();
+    lua.pushBoolean(true);
+    try std.testing.expect(!lua.equal(-2, -1));
+
+    lua.pop(2);
+    lua.pushNil();
+    lua.pushNil();
+    try std.testing.expect(lua.equal(-2, -1));
+
+    lua.pop(2);
+    lua.pushBoolean(true);
+    lua.pushBoolean(false);
+    try std.testing.expect(!lua.equal(-2, -1));
+
+    lua.pop(2);
+    lua.pushBoolean(true);
+    lua.pushBoolean(true);
+    try std.testing.expect(lua.equal(-2, -1));
+}