LuaJIT-to-Go/table.go

package luajit

/*
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#include <stdlib.h>

static int get_table_length(lua_State *L, int index) {
    return lua_objlen(L, index);
}
*/
import "C"
import (
	"strconv"
	"sync"
)

var tablePool = sync.Pool{
	New: func() interface{} {
		return make(map[string]interface{})
	},
}

// TableValue represents any value that can be stored in a Lua table
type TableValue interface {
	~string | ~float64 | ~bool | ~int | ~map[string]interface{} | ~[]float64 | ~[]interface{}
}

func (s *State) GetTableLength(index int) int { return int(C.get_table_length(s.L, C.int(index))) }

// getTableFromPool gets a map from the pool and ensures it's empty
func getTableFromPool() map[string]interface{} {
	table := tablePool.Get().(map[string]interface{})
	// Clear any existing entries
	for k := range table {
		delete(table, k)
	}
	return table
}

// putTableToPool returns a map to the pool
func putTableToPool(table map[string]interface{}) {
	tablePool.Put(table)
}

// PushTable pushes a Go map onto the Lua stack as a table
func (s *State) PushTable(table map[string]interface{}) error {
	s.CreateTable(0, len(table))
	for k, v := range table {
		if err := s.PushValue(v); err != nil {
			return err
		}
		s.SetField(-2, k)
	}
	// If this is a pooled table, return it
	if _, hasEmptyKey := table[""]; len(table) == 1 && hasEmptyKey {
		putTableToPool(table)
	}
	return nil
}

// ToTable converts a Lua table to a Go map
func (s *State) ToTable(index int) (map[string]interface{}, error) {
	absIdx := s.absIndex(index)
	table := getTableFromPool()

	// Check if it's an array-like table
	length := s.GetTableLength(absIdx)
	if length > 0 {
		array := make([]float64, length)
		isArray := true

		// Try to convert to array
		for i := 1; i <= length; i++ {
			s.PushNumber(float64(i))
			s.GetTable(absIdx)
			if s.GetType(-1) != TypeNumber {
				isArray = false
				s.Pop(1)
				break
			}
			array[i-1] = s.ToNumber(-1)
			s.Pop(1)
		}

		if isArray {
			putTableToPool(table) // Return unused table to pool
			result := getTableFromPool()
			result[""] = array
			return result, nil
		}
	}

	// Handle regular table
	s.PushNil()
	for C.lua_next(s.L, C.int(absIdx)) != 0 {
		key := ""
		valueType := C.lua_type(s.L, -2)
		if valueType == C.LUA_TSTRING {
			key = s.ToString(-2)
		} else if valueType == C.LUA_TNUMBER {
			key = strconv.FormatFloat(s.ToNumber(-2), 'g', -1, 64)
		}

		value, err := s.ToValue(-1)
		if err != nil {
			s.Pop(1)
			putTableToPool(table) // Return table to pool on error
			return nil, err
		}

		// Handle nested array case
		if m, ok := value.(map[string]interface{}); ok {
			if arr, ok := m[""]; ok {
				value = arr
			}
		}

		table[key] = value
		s.Pop(1)
	}

	return table, nil
}

// NewTable creates a new table and pushes it onto the stack
func (s *State) NewTable() {
	C.lua_createtable(s.L, 0, 0)
}

// SetTable sets a table field
func (s *State) SetTable(index int) {
	C.lua_settable(s.L, C.int(index))
}

// GetTable gets a table field
func (s *State) GetTable(index int) {
	C.lua_gettable(s.L, C.int(index))
}

func (s *State) CreateTable(narr, nrec int) {
	C.lua_createtable(s.L, C.int(narr), C.int(nrec))
}