c/lua:metatable

2024-07-28 09:46:45 +08:00
parent 5428730e7a
commit 35ba69a175
2 changed files with 192 additions and 57 deletions
--- a/c/lua/_demo/metatable/metatable.go
+++ b/c/lua/_demo/metatable/metatable.go
@@ -0,0 +1,125 @@
+package main
+
+import (
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/lua"
+)
+
+func toString(L *lua.State) c.Int {
+	L.Pushstring(c.Str("Hello from metatable!"))
+	return 1
+}
+
+func printStack(L *lua.State, message string) {
+	top := L.Gettop()
+	c.Printf(c.Str("%s - Stack size: %d\n"), c.AllocaCStr(message), c.Int(top))
+	for i := c.Int(1); i <= top; i++ {
+		t := L.Type(i)
+		switch t {
+		case c.Int(lua.STRING):
+			c.Printf(c.Str("  %d: string: %s\n"), c.Int(i), L.Tostring(i))
+		case c.Int(lua.BOOLEAN):
+			c.Printf(c.Str("  %d: boolean: %v\n"), c.Int(i), L.Toboolean(i))
+		case c.Int(lua.NUMBER):
+			c.Printf(c.Str("  %d: number: %f\n"), c.Int(i), L.Tonumber(i))
+		default:
+			c.Printf(c.Str("  %d: %s\n"), c.Int(i), L.Typename(t))
+		}
+	}
+}
+
+func main() {
+	L := lua.Newstate()
+	defer L.Close()
+
+	L.Openlibs()
+
+	L.Newtable()
+	printStack(L, "After creating main table")
+
+	L.Newtable()
+	printStack(L, "After creating metatable")
+
+	L.Pushcfunction(toString)
+	printStack(L, "After Push CFunction")
+
+	L.Setfield(-2, c.Str("__tostring"))
+	printStack(L, "After setting __tostring")
+
+	if L.Setmetatable(-2) == 0 {
+		c.Printf(c.Str("Failed to set metatable\n"))
+	}
+	printStack(L, "After setting metatable")
+
+	L.Setglobal(c.Str("obj"))
+	printStack(L, "After setting global obj")
+
+	testcode := c.Str(`
+		if obj == nil then
+			print('obj is not defined')
+		else
+			local mt = getmetatable(obj)
+			if not mt then
+				print('Metatable not set')
+			elseif not mt.__tostring then
+				print('__tostring not set in metatable')
+			else
+				print(mt.__tostring(obj))
+			end
+		end
+	`)
+
+	if L.Dostring(testcode) != lua.OK {
+		c.Printf(c.Str("Error: %s\n"), L.Tostring(-1))
+	}
+
+	L.Getglobal(c.Str("obj"))
+	if L.Getmetatable(-1) != 0 {
+		c.Printf(c.Str("Metatable get success\n"))
+		L.Pushstring(c.Str("__tostring"))
+		L.Gettable(-2)
+		if L.Isfunction(-1) {
+			c.Printf(c.Str("__tostring function found in metatable\n"))
+			if L.Iscfunction(-1) != 0 {
+				c.Printf(c.Str("__tostring is a C function\n"))
+				cfunc := L.Tocfunction(-1)
+				if cfunc != nil {
+					c.Printf(c.Str("Successfully retrieved __tostring C function pointer\n"))
+					L.Pushcfunction(cfunc)
+					if L.Call(0, 1) == lua.OK {
+						result := L.Tostring(-1)
+						c.Printf(c.Str("Result of calling __tostring: %s\n"), result)
+					}
+				}
+			}
+		} else {
+			c.Printf(c.Str("__tostring function not found in metatable\n"))
+		}
+	} else {
+		c.Printf(c.Str("No metatable found using GetTable\n"))
+	}
+}
+
+/* Expected output:
+After creating main table - Stack size: 1
+  1: table
+After creating metatable - Stack size: 2
+  1: table
+  2: table
+After Push CFunction - Stack size: 3
+  1: table
+  2: table
+  3: function
+After setting __tostring - Stack size: 2
+  1: table
+  2: table
+After setting metatable - Stack size: 1
+  1: table
+After setting global obj - Stack size: 0
+Hello from metatable!
+Metatable get success
+__tostring function found in metatable
+__tostring is a C function
+Successfully retrieved __tostring C function pointer
+Result of calling __tostring: Hello from metatable!
+*/