reorganize: consolidate demo directories

- Consolidate _demo, _pydemo, _embdemo into single _demo directory structure
- Organize demos by language: _demo/{go,py,c,embed}/
- Categorize demos based on imports:
- Python library demos (py imports) → _demo/py/
- C/C++ library demos (c/cpp imports) → _demo/c/
- Go-specific demos → _demo/go/
- Embedded demos → _demo/embed/
- Move C-related demos (asm*, cabi*, cgo*, linkname, targetsbuild) from go/ to c/
- Update all path references in README.md and GitHub workflows
- Improve demo organization and navigation as requested in #1256

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

_demo/go/async/async/async.go

@@ -0,0 +1,31 @@
+package async
+
+import (
+	_ "unsafe"
+)
+
+type Void = [0]byte
+
+type Future[T any] interface {
+	Then(cb func(T))
+}
+
+type future[T any] struct {
+	cb func(func(T))
+}
+
+func (f *future[T]) Then(cb func(T)) {
+	f.cb(cb)
+}
+
+func Async[T any](fn func(func(T))) Future[T] {
+	return &future[T]{fn}
+}
+
+func Run[T any](future Future[T]) T {
+	var ret T
+	future.Then(func(v T) {
+		ret = v
+	})
+	return ret
+}

_demo/go/async/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"time"
+
+	"github.com/goplus/llgo/_demo/go/async/async"
+	"github.com/goplus/llgo/_demo/go/async/timeout"
+)
+
+func Sleep(i int, d time.Duration) async.Future[int] {
+	return async.Async(func(resolve func(int)) {
+		timeout.Timeout(d).Then(func(async.Void) {
+			resolve(i)
+		})
+	})
+}
+
+func main() {
+	async.Run(async.Async(func(resolve func(async.Void)) {
+		println("read file")
+		defer resolve(async.Void{})
+	}))
+}

_demo/go/async/timeout/timeout.go

@@ -0,0 +1,16 @@
+package timeout
+
+import (
+	"time"
+
+	"github.com/goplus/llgo/_demo/go/async/async"
+)
+
+func Timeout(d time.Duration) async.Future[async.Void] {
+	return async.Async(func(resolve func(async.Void)) {
+		go func() {
+			time.Sleep(d)
+			resolve(async.Void{})
+		}()
+	})
+}

_demo/go/checkfile/demo.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+func main() {
+	tempDir := os.TempDir()
+	noexist := filepath.Join(tempDir, "noexist.txt")
+
+	if _, err := os.Stat(noexist); err != nil {
+		if os.IsNotExist(err) {
+			fmt.Println("noexist:", err.Error())
+		} else {
+			fmt.Println("exist,other err:", err.Error())
+		}
+	}
+
+	if _, err := os.Open(noexist); err != nil {
+		if os.IsNotExist(err) {
+			fmt.Println("noexist:", err.Error())
+		} else {
+			fmt.Println("exist,other err:", err.Error())
+		}
+	}
+}

_demo/go/commandrun/commandrun.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"bytes"
+	"os/exec"
+	"path/filepath"
+)
+
+func main() {
+	var data bytes.Buffer
+	cmd := exec.Command("echo", "hello llgo")
+	cmd.Dir = filepath.Dir("./")
+	cmd.Stdout = &data
+	err := cmd.Run()
+	if err != nil {
+		panic(err)
+	}
+	println("len:", len(data.Bytes()))
+	println("data:", data.String())
+}

_demo/go/complex/cmplx.go

@@ -0,0 +1,9 @@
+package main
+
+import (
+	"math/cmplx"
+)
+
+func main() {
+	println("abs(3+4i):", cmplx.Abs(3+4i))
+}

_demo/go/defer/main.go

@@ -0,0 +1,18 @@
+package main
+
+func main() {
+	var a int = 5
+	defer println(a)
+	defer func() {
+		println(a)
+	}()
+	defer func() {
+		println(recover().(string))
+	}()
+	a = 10
+	panic("error")
+	//Output:
+	// error
+	// 10
+	// 5
+}

_demo/go/failed/stacktrace/main.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+)
+
+type MyStruct[T any] struct {
+	value T
+}
+
+func (m *MyStruct[T]) Method() {
+	fmt.Println("In generic method")
+	genericFunc[T](m.value)
+}
+
+func genericFunc[T any](v T) {
+	fmt.Println("In generic function")
+	normalFunc()
+}
+
+func normalFunc() {
+	fmt.Println("In normal function")
+	panic("panic occurs here")
+}
+
+func main() {
+	m := &MyStruct[string]{value: "hello"}
+	m.Method()
+}
+
+//Expected:
+// In generic method
+// In generic function
+// In normal function
+// panic: panic occurs here
+
+// [0x00C6D310 github.com/goplus/llgo/internal/runtime.Rethrow+0x2f, SP = 0x60]
+// [0x00C6CF44 github.com/goplus/llgo/internal/runtime.Panic+0x2d, SP = 0x50]
+// [0x00C69420 main.normalFunc+0xf, SP = 0xa8]
+// [0x00C69564 main.genericFunc[string]+0x18, SP = 0x74]
+// [0x00C694A8 main.(*MyStruct[string]).Method+0x1f, SP = 0x84]
+// [0x00C6936C main+0x4, SP = 0x40]

_demo/go/go.mod

@@ -0,0 +1,3 @@
+module github.com/goplus/llgo/_demo/go
+
+go 1.20

_demo/go/goroutine/goroutine.go

@@ -0,0 +1,12 @@
+package main
+
+func main() {
+	done := false
+	go func() {
+		println("Hello, goroutine")
+		done = true
+	}()
+	for !done {
+		print(".")
+	}
+}

_demo/go/gotime/time.go

@@ -0,0 +1,7 @@
+package main
+
+import "time"
+
+func main() {
+	println(time.Now().String())
+}

_demo/go/ifaceconv/main.go

@@ -0,0 +1,85 @@
+package main
+
+// Tests of interface conversions and type assertions.
+
+type I0 interface {
+}
+type I1 interface {
+	f()
+}
+type I2 interface {
+	f()
+	g()
+}
+
+type C0 struct{}
+type C1 struct{}
+
+func (C1) f() {}
+
+type C2 struct{}
+
+func (C2) f() {}
+func (C2) g() {}
+
+func main() {
+	var i0 I0
+	var i1 I1
+	var i2 I2
+
+	// Nil always causes a type assertion to fail, even to the
+	// same type.
+	if _, ok := i0.(I0); ok {
+		panic("nil i0.(I0) succeeded")
+	}
+	if _, ok := i1.(I1); ok {
+		panic("nil i1.(I1) succeeded")
+	}
+	if _, ok := i2.(I2); ok {
+		panic("nil i2.(I2) succeeded")
+	}
+
+	// Conversions can't fail, even with nil.
+	_ = I0(i0)
+
+	_ = I0(i1)
+	_ = I1(i1)
+
+	_ = I0(i2)
+	_ = I1(i2)
+	_ = I2(i2)
+
+	// Non-nil type assertions pass or fail based on the concrete type.
+	i1 = C1{}
+	if _, ok := i1.(I0); !ok {
+		panic("C1 i1.(I0) failed")
+	}
+	if _, ok := i1.(I1); !ok {
+		panic("C1 i1.(I1) failed")
+	}
+	if _, ok := i1.(I2); ok {
+		panic("C1 i1.(I2) succeeded")
+	}
+
+	i1 = C2{}
+	if _, ok := i1.(I0); !ok {
+		panic("C2 i1.(I0) failed")
+	}
+	if _, ok := i1.(I1); !ok {
+		panic("C2 i1.(I1) failed")
+	}
+	if _, ok := i1.(I2); !ok {
+		panic("C2 i1.(I2) failed")
+	}
+
+	// Conversions can't fail.
+	i1 = C1{}
+	if I0(i1) == nil {
+		panic("C1 I0(i1) was nil")
+	}
+	if I1(i1) == nil {
+		panic("C1 I1(i1) was nil")
+	}
+
+	println("pass")
+}

_demo/go/logdemo/log.go

@@ -0,0 +1,9 @@
+package main
+
+import (
+	"log"
+)
+
+func main() {
+	log.Println("Hello")
+}

_demo/go/math/math.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"math"
+)
+
+func main() {
+	println(math.Sqrt(2))
+	println(math.Abs(-1.2))
+	println(math.Ldexp(1.2, 3))
+}

_demo/go/mimeheader/mimeheader.go

@@ -0,0 +1,13 @@
+package main
+
+import "net/textproto"
+
+func main() {
+	h := make(textproto.MIMEHeader)
+	h.Set("host", "www.example.com")
+	println(h.Get("Host"))
+}
+
+/* Expected output:
+www.example.com
+*/

_demo/go/mkdirdemo/mkdir.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+func main() {
+	tempDir, err := os.MkdirTemp("", "example*")
+	if err != nil {
+		fmt.Println("Failed to create temp directory:", err)
+		return
+	}
+	defer os.Remove(tempDir)
+	fmt.Println("Temp directory:", tempDir)
+
+	tempFile, err := os.CreateTemp("", "example*.txt")
+	if err != nil {
+		fmt.Println("Failed to create temp file:", err)
+		return
+	}
+	defer tempFile.Close()
+	defer os.Remove(tempFile.Name())
+	fmt.Println("Temp file:", tempFile.Name())
+
+	nestedDir := filepath.Join("nested", "directory")
+	err = os.MkdirAll(nestedDir, 0755)
+	if err != nil {
+		fmt.Println("Failed to create nested directory:", err)
+		return
+	}
+	fmt.Println("Nest directory:", nestedDir)
+}

_demo/go/oslookpath/lookpath.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+)
+
+func main() {
+	ls := "ls"
+	if runtime.GOOS == "windows" {
+		ls = "dir"
+	}
+	lspath, _ := exec.LookPath(ls)
+	if lspath != "" {
+		ls = lspath
+	}
+	fmt.Println(ls)
+}

_demo/go/randcrypt/rand.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"crypto/rand"
+	"fmt"
+)
+
+func main() {
+	c := 10
+	b := make([]byte, c)
+	_, err := rand.Read(b)
+	if err != nil {
+		fmt.Println("error:", err)
+		return
+	}
+	// The slice should now contain random bytes instead of only zeroes.
+	fmt.Printf("%x\n", b)
+}

_demo/go/randdemo/rand.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+)
+
+func main() {
+	fmt.Println(rand.Intn(100))
+	fmt.Println(rand.Intn(100))
+	fmt.Println(rand.Intn(100))
+}

_demo/go/readdir/main.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	entries, err := os.ReadDir("../")
+	if err != nil {
+		panic(err)
+	}
+	if len(entries) == 0 {
+		panic("No files found")
+	}
+	var check int
+	for _, e := range entries {
+		fmt.Printf("%s isDir[%t]\n", e.Name(), e.IsDir())
+		if !e.IsDir() {
+			switch e.Name() {
+			case "go.sum", "go.mod":
+				check++
+			}
+		}
+	}
+	if check != 2 {
+		panic("Bad readdir entries go.mod/go.sum")
+	}
+}

_demo/go/reflectfunc/reflectfunc.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func add(a, b int) int {
+	return a + b
+}
+
+func main() {
+	fn := func(a, b int) int {
+		return a + b
+	}
+	var i int
+	fn1 := func() {
+		i++
+	}
+	fn2 := func() func() {
+		return func() {
+			println("closure", i)
+		}
+	}
+
+	fns := []any{add, fn, fn1, fn2}
+	for _, fn := range fns {
+		v := reflect.ValueOf(fn)
+		fmt.Println(v.Type())
+		fmt.Println(v.Kind())
+		if v.Kind() != reflect.Func {
+			panic(fmt.Sprintf("not func: %T", fn))
+		}
+
+		t := v.Type()
+		fmt.Println(t)
+		fmt.Println(t.Kind())
+		if t.Kind() != reflect.Func {
+			panic(fmt.Sprintf("not func: %T", fn))
+		}
+	}
+}

_demo/go/sync/sync.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// Counter represents a thread-safe counter
+type Counter struct {
+	mu    sync.Mutex
+	value int64
+}
+
+// Increment increases the counter value by 1
+func (c *Counter) Increment() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.value++
+}
+
+// GetValue returns the current value of the counter
+func (c *Counter) GetValue() int64 {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.value
+}
+
+// Constant values for the test
+const (
+	numGoroutines = 64
+	numIterations = 10000
+	expectedTotal = numGoroutines * numIterations
+)
+
+func main() {
+	// Create a new counter instance
+	counter := &Counter{}
+
+	// Create a wait group to wait for all goroutines to finish
+	var wg sync.WaitGroup
+
+	// Track active goroutines for monitoring
+	var activeGoroutines int32
+
+	// Start time
+	startTime := time.Now()
+
+	// Launch goroutines
+	for i := 0; i < numGoroutines; i++ {
+		wg.Add(1)
+		atomic.AddInt32(&activeGoroutines, 1)
+
+		go func(id int) {
+			defer func() {
+				wg.Done()
+				atomic.AddInt32(&activeGoroutines, -1)
+			}()
+
+			// Each goroutine increments the counter numIterations times
+			for j := 0; j < numIterations; j++ {
+				counter.Increment()
+
+				// Simulate varying workload with random sleeps
+				if j%100 == 0 {
+					time.Sleep(time.Microsecond)
+				}
+			}
+			fmt.Printf("Goroutine %d finished\n", id)
+		}(i)
+	}
+
+	// Monitor progress in a separate goroutine
+	go func() {
+		for {
+			active := atomic.LoadInt32(&activeGoroutines)
+			if active == 0 {
+				break
+			}
+			fmt.Printf("Active goroutines: %d\n", active)
+			time.Sleep(time.Second)
+		}
+	}()
+
+	// Wait for all goroutines to complete
+	wg.Wait()
+
+	// Calculate execution time
+	duration := time.Since(startTime)
+
+	// Get and verify the final result
+	finalValue := counter.GetValue()
+	fmt.Printf("\nExecution completed in: %v\n", duration)
+	fmt.Printf("Final counter value: %d\n", finalValue)
+	fmt.Printf("Expected value: %d\n", expectedTotal)
+
+	// Assert the result
+	if finalValue != expectedTotal {
+		panic(fmt.Sprintf("ERROR: Counter value mismatch! Expected %d, got %d\n",
+			expectedTotal, finalValue))
+	} else {
+		fmt.Printf("SUCCESS: Counter value matches expected total\n")
+	}
+
+	// Print some statistics
+	opsPerSecond := float64(expectedTotal) / duration.Seconds()
+	fmt.Printf("\nStatistics:\n")
+	fmt.Printf("Operations per second: %.2f\n", opsPerSecond)
+	fmt.Printf("Average time per operation: %.2f ns\n",
+		float64(duration.Nanoseconds())/float64(expectedTotal))
+}

_demo/go/sysexec/exec.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+	"syscall"
+)
+
+func main() {
+	ls := "ls"
+	args := []string{ls, "-l"}
+	if runtime.GOOS == "windows" {
+		ls = "dir"
+		args = []string{ls}
+	}
+	lspath, _ := exec.LookPath(ls)
+	if lspath != "" {
+		ls = lspath
+	}
+	err := syscall.Exec(ls, args, nil)
+	if err != nil {
+		fmt.Println("syscall.Exec error:", err)
+		return
+	}
+}

_demo/go/timedur/timedur.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	t := time.Now().Add(time.Second * 5)
+	fmt.Println(time.Until(t))
+}