refactor: change toString to toBytes

The Lua API has the concept of lstrings (length strings). These are used
when the contents may contain zeroes, or when it is useful to know the
length. Because this data is not necessarily a string, ziglua has
renamed these lstring functions to bytes functions.

The toString function returns a zero-terminated many item pointer which
is useful when you know the data is not zero-terminated.

Author: natecraddock

src/tests.zig

@@ -250,7 +250,7 @@ test "type of and getting values" {
     _ = lua.pushString("all your codebase are belong to us");
     try expectEqual(@as(?[*]const u8, null), lua.pushString(null));
     lua.pushCFunction(ziglua.wrap(add));
-    _ = lua.pushLString("hello world");
+    _ = lua.pushBytes("hello world");
     _ = lua.pushFString("%s %s %d", .{ "hello", "world", @as(i32, 10) });
     lua.pushValue(1);
 
@@ -285,7 +285,7 @@ test "type of and getting values" {
     try expect(lua.isString(12));
     try expect(lua.isBoolean(13));
 
-    try expectEqualStrings("hello world 10", lua.toString(12).?);
+    try expectEqualStrings("hello world 10", try lua.toBytes(12));
 
     // the created thread should equal the main thread (but created thread has no allocator ref)
     try expectEqual(lua.state, (try lua.toThread(7)).state);
@@ -466,7 +466,7 @@ test "string buffers" {
     try expectEqualStrings("ziglua api some text here", buffer.addr());
 
     buffer.pushResult();
-    try expectEqualStrings("ziglua api some text here", lua.toString(-1).?);
+    try expectEqualStrings("ziglua api some text here", try lua.toBytes(-1));
 
     // now test a small buffer
     buffer = undefined;
@@ -478,7 +478,7 @@ test "string buffers" {
     b = buffer.prep();
     std.mem.copy(u8, b, "defghijklmnopqrstuvwxyz");
     buffer.pushResultSize(23);
-    try expectEqualStrings("abcdefghijklmnopqrstuvwxyz", lua.toString(-1).?);
+    try expectEqualStrings("abcdefghijklmnopqrstuvwxyz", try lua.toBytes(-1));
 
     lua.len(-1);
     try expectEqual(@as(Integer, 26), lua.toInteger(-1));
@@ -587,7 +587,7 @@ test "concat" {
     _ = lua.pushString(" wow!");
     lua.concat(3);
 
-    try expectEqualStrings("hello 10.0 wow!", lua.toString(-1).?);
+    try expectEqualStrings("hello 10.0 wow!", try lua.toBytes(-1));
 }
 
 test "garbage collector" {
@@ -627,14 +627,14 @@ test "table access" {
     _ = lua.getGlobal("a");
 
     try expectEqual(LuaType.string, lua.getIndex(1, 1));
-    try expectEqualStrings("first", lua.toString(-1).?);
+    try expectEqualStrings("first", try lua.toBytes(-1));
 
     try expectEqual(LuaType.string, lua.rawGetIndex(1, 1));
-    try expectEqualStrings("first", lua.toString(-1).?);
+    try expectEqualStrings("first", try lua.toBytes(-1));
 
     _ = lua.pushString("key");
     try expectEqual(LuaType.string, lua.getTable(1));
-    try expectEqualStrings("value", lua.toString(-1).?);
+    try expectEqualStrings("value", try lua.toBytes(-1));
 
     _ = lua.pushString("other one");
     try expectEqual(LuaType.number, lua.rawGetTable(1));
@@ -803,7 +803,7 @@ test "userdata and uservalues" {
     try expectEqual(LuaType.number, try lua.getIndexUserValue(1, 1));
     try expectEqual(@as(Number, 1234.56), lua.toNumber(-1));
     try expectEqual(LuaType.string, try lua.getIndexUserValue(1, 2));
-    try expectEqualStrings("test string", lua.toString(-1).?);
+    try expectEqualStrings("test string", try lua.toBytes(-1));
 
     try expectError(Error.Fail, lua.setIndexUserValue(1, 3));
     try expectError(Error.Fail, lua.getIndexUserValue(1, 3));
@@ -854,15 +854,15 @@ test "table traversal" {
     while (lua.next(1)) {
         switch (lua.typeOf(-1)) {
             .string => {
-                try expectEqualStrings("key", lua.toString(-2).?);
-                try expectEqualStrings("value", lua.toString(-1).?);
+                try expectEqualStrings("key", try lua.toBytes(-2));
+                try expectEqualStrings("value", try lua.toBytes(-1));
             },
             .boolean => {
-                try expectEqualStrings("second", lua.toString(-2).?);
+                try expectEqualStrings("second", try lua.toBytes(-2));
                 try expectEqual(true, lua.toBoolean(-1));
             },
             .number => {
-                try expectEqualStrings("third", lua.toString(-2).?);
+                try expectEqualStrings("third", try lua.toBytes(-2));
                 try expectEqual(@as(Integer, 1), lua.toInteger(-1));
             },
             else => unreachable,
@@ -883,7 +883,7 @@ test "registry" {
 
     // get key from the registry
     _ = lua.rawGetPtr(ziglua.registry_index, key);
-    try expectEqualStrings("hello there", lua.toString(-1).?);
+    try expectEqualStrings("hello there", try lua.toBytes(-1));
 }
 
 test "closing vars" {
@@ -931,7 +931,7 @@ test "raise error" {
 
     lua.pushCFunction(ziglua.wrap(makeError));
     try expectError(Error.Runtime, lua.protectedCall(0, 0, 0));
-    try expectEqualStrings("makeError made an error", lua.toString(-1).?);
+    try expectEqualStrings("makeError made an error", try lua.toBytes(-1));
 }
 
 fn continuation(l: *Lua, status: ziglua.Status, ctx: isize) i32 {
@@ -973,7 +973,7 @@ test "yielding" {
         thread.pop(results);
     }
     try expectEqual(ziglua.ResumeStatus.ok, try thread.resumeThread(lua, 0, &results));
-    try expectEqualStrings("done", thread.toString(-1).?);
+    try expectEqualStrings("done", try thread.toBytes(-1));
 }
 
 test "refs" {

src/ziglua.zig

@@ -716,7 +716,7 @@ pub const Lua = struct {
     // }
 
     /// Pushes the bytes onto the stack. Returns a slice pointing to Lua's internal copy of the string
-    pub fn pushLString(lua: *Lua, str: []const u8) []const u8 {
+    pub fn pushBytes(lua: *Lua, str: []const u8) []const u8 {
         return c.lua_pushlstring(lua.state, str.ptr, str.len)[0..str.len];
     }
 
@@ -951,8 +951,14 @@ pub const Lua = struct {
         return result;
     }
 
-    // NOTE: No need to have both toLString and toString for a Zig API
-    // pub fn toLString(lua: *Lua, index: i32) []const u8 { ... }
+    /// Returns a slice of bytes at the given index
+    /// If the value is not a string or number, returns an error
+    /// If the value was a number the actual value in the stack will be changed to a string
+    pub fn toBytes(lua: *Lua, index: i32) ![:0]const u8 {
+        var length: usize = undefined;
+        if (c.lua_tolstring(lua.state, index, &length)) |ptr| return ptr[0..length :0];
+        return Error.Fail;
+    }
 
     /// Equivalent to toNumberX but does not return errors
     pub fn toNumber(lua: *Lua, index: i32) Number {
@@ -975,14 +981,14 @@ pub const Lua = struct {
         return Error.Fail;
     }
 
-    /// Converts the Lua value at the given `index` to a zero-terminated slice (string)
-    /// Returns null if the value was not a string or number
+    /// Converts the Lua value at the given `index` to a zero-terminated many-itemed-pointer (string)
+    /// Returns an error if the conversion failed
     /// If the value was a number the actual value in the stack will be changed to a string
-    pub fn toString(lua: *Lua, index: i32) ?[:0]const u8 {
+    pub fn toString(lua: *Lua, index: i32) ![*:0]const u8 {
         var length: usize = undefined;
         if (c.lua_tolstring(lua.state, index, &length)) |str| {
-            return str[0..length :0];
-        } else return null;
+            return std.mem.span(str);
+        } else return Error.Fail;
     }
 
     /// Converts the value at the given `index` to a Lua thread (wrapped with a `Lua` struct)