Rework Buffer formats;

Summary:

- Buffer length can be zero (indicates single value instead of array)
- Internally, arrays aren't coerced to array-of-single-struct
- Removes support for "flat table" data (array-of-structs w/o wrapping
  each struct in a nested table)
- Use consistent syntax for reading table data into buffers:
  - Numbers are numbers
  - Vectors are numbers, tables, or vectors
  - Structs are tables with any combination of integer/string keys
    - Fields are assigned from integer keys in order, then any remaining
      fields use the string keys
  - Arrays are tables of elements, formatted as above
- Try to improve error messages for Buffer:setData errors

src/api/api.h

@@ -160,17 +160,10 @@ bool luax_writefile(const char* filename, const void* data, size_t size);
 struct DataField;
 struct Material;
 struct ColoredString;
-void luax_checkfieldn(lua_State* L, int index, int type, void* data);
-void luax_checkfieldv(lua_State* L, int index, int type, void* data);
-void luax_checkfieldt(lua_State* L, int index, int type, void* data);
-uint32_t luax_checkfieldarray(lua_State* L, int index, const struct DataField* array, char* data);
-void luax_checkdataflat(lua_State* L, int index, int subindex, uint32_t count, const struct DataField* format, char* data);
-void luax_checkdatatuples(lua_State* L, int index, int start, uint32_t count, const struct DataField* format, char* data);
-void luax_checkdatakeys(lua_State* L, int index, int start, uint32_t count, const struct DataField* array, char* data);
-void luax_checkstruct(lua_State* L, int index, const struct DataField* fields, uint32_t count, char* data);
+void luax_checkbufferdata(lua_State* L, int index, const struct DataField* format, char* data);
 int luax_pushbufferdata(lua_State* L, const struct DataField* format, uint32_t count, char* data);
 void luax_pushbufferformat(lua_State* L, const struct DataField* fields, uint32_t count);
-uint32_t luax_gettablestride(lua_State* L, int index, int subindex, struct DataField* fields, uint32_t count);
+int luax_gettablestride(lua_State* L, int type);
 uint32_t luax_checkcomparemode(lua_State* L, int index);
 struct Material* luax_optmaterial(lua_State* L, int index);
 struct ColoredString* luax_checkcoloredstrings(lua_State* L, int index, uint32_t* count, struct ColoredString* stack);

src/api/l_graphics.c

@@ -625,13 +625,12 @@ static int l_lovrGraphicsNewBuffer(lua_State* L) {
     lovrCheck(blob->size < UINT32_MAX, "Blob is too big to create a Buffer");
     info.size = (uint32_t) blob->size;
   } else if (type == LUA_TSTRING) {
-    info.fieldCount = 2;
+    info.fieldCount = 1;
     info.format = format;
-    format[0] = (DataField) { .fieldCount = 1 };
-    format[1] = (DataField) { .type = luax_checkdatatype(L, 1) };
+    format[0] = (DataField) { .type = luax_checkdatatype(L, 1) };
   } else if (type == LUA_TTABLE) {
     info.format = format;
-    format[0] = (DataField) { .fieldCount = luax_len(L, 1) };
+    format[0] = (DataField) { .fieldCount = luax_len(L, 1), .fields = format + 1 };
 
     lua_rawgeti(L, 1, 1);
     bool anonymous = lua_type(L, -1) == LUA_TSTRING;
@@ -646,6 +645,12 @@ static int l_lovrGraphicsNewBuffer(lua_State* L) {
         format[i] = (DataField) { .type = luax_checkdatatype(L, -1) };
         lua_pop(L, 1);
       }
+
+      // Convert single-field anonymous formats to regular arrays
+      if (format->fieldCount == 1) {
+        format->type = format[1].type;
+        format->fieldCount = 0;
+      }
     } else {
       info.fieldCount = 1;
       luax_checkbufferformat(L, 1, format, &info.fieldCount, COUNTOF(format));
@@ -664,19 +669,18 @@ static int l_lovrGraphicsNewBuffer(lua_State* L) {
 
   // Length/size
   if (info.format) {
-    format->fields = format + 1;
     lovrGraphicsAlignFields(format, layout);
     switch (lua_type(L, 2)) {
-      case LUA_TNIL: case LUA_TNONE: format->length = 1; break;
+      case LUA_TNIL: case LUA_TNONE: format->length = 0; break;
       case LUA_TNUMBER: format->length = luax_checku32(L, 2); break;
       case LUA_TTABLE:
         lua_rawgeti(L, 2, 1);
-        if (lua_istable(L, -1)) {
-          format->length = luax_len(L, -2);
-        } else if (lua_isnil(L, -1) && format->fields[0].name) {
-          format->length = 1;
+        if (lua_type(L, -1) == LUA_TNUMBER) {
+          lovrCheck(format->fieldCount <= 1, "Struct data must be provided as a table of tables");
+          DataType type = format->fieldCount == 0 ? format->type : format->fields[0].type;
+          format->length = luax_len(L, -2) / luax_gettablestride(L, type);
         } else {
-          format->length = luax_len(L, -2) / luax_gettablestride(L, 2, 1, format->fields, format->fieldCount);
+          format->length = luax_len(L, -2);
         }
         lua_pop(L, 1);
         hasData = true;
@@ -688,7 +692,7 @@ static int l_lovrGraphicsNewBuffer(lua_State* L) {
           format->length = info.size / format->stride;
           break;
         } else if (luax_tovector(L, 2, NULL)) {
-          format->length = 1;
+          format->length = 0;
           hasData = true;
           break;
         }
@@ -703,25 +707,7 @@ static int l_lovrGraphicsNewBuffer(lua_State* L) {
   if (blob) {
     memcpy(data, blob->data, info.size);
   } else if (hasData) {
-    if (luax_tovector(L, 2, NULL)) {
-      luax_checkfieldv(L, 2, format->fields[0].type, data);
-    } else if (luax_len(L, 2) == 0 && format->fields[0].name) {
-      luax_checkstruct(L, 2, format->fields, format->fieldCount, data);
-    } else {
-      lua_rawgeti(L, 2, 1);
-      bool complexFormat = lovrBufferGetInfo(buffer)->complexFormat;
-      bool tableOfTables = complexFormat || lua_istable(L, -1);
-      bool tuples = tableOfTables && !complexFormat && (luax_len(L, -1) > 0 || !format->fields[0].name);
-      lua_pop(L, 1);
-
-      if (tuples) {
-        luax_checkdatatuples(L, 2, 1, format->length, format, data);
-      } else if (tableOfTables) {
-        luax_checkdatakeys(L, 2, 1, format->length, format, data);
-      } else {
-        luax_checkdataflat(L, 2, 1, format->length, format, data);
-      }
-    }
+    luax_checkbufferdata(L, 2, format, data);
   }
 
   luax_pushtype(L, Buffer, buffer);
@@ -1403,7 +1389,7 @@ static int l_lovrGraphicsNewMesh(lua_State* L) {
   if (blob) {
     memcpy(vertices, blob->data, blob->size);
   } else if (hasData) {
-    luax_checkdatatuples(L, index, 1, format->length, lovrMeshGetVertexFormat(mesh), vertices);
+    luax_checkbufferdata(L, index, lovrMeshGetVertexFormat(mesh), vertices);
   }
 
   luax_pushtype(L, Mesh, mesh);