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package main
// lingua evalia
//
// try it with `curl -i localhost:8000/run --data-binary @hello-world.go`
import (
"fmt"
"html/template"
"io/ioutil"
"log"
"net/http"
"os"
"os/exec"
)
type Language interface {
Eval(code string) (result []byte, err error)
}
type LanguageGo struct{}
var Go = LanguageGo{}
func (g LanguageGo) Eval(code string) ([]byte, error) {
// write code to temp file
f, err := writeCode(code)
defer f.Close()
if err != nil {
return nil, err
}
// `go run` it
res, err := runCode(f)
if err != nil {
return res, err
}
// remove the file
os.Remove(f.Name())
// return output
return res, nil
}
func writeCode(code string) (*os.File, error) {
// create tmp file
f, err := os.Create("/tmp/linguaevalia-go.go") // FIXME: actually create a tmpfile
if err != nil {
return f, err
}
// write code to it
_, err = f.Write([]byte(code))
if err != nil {
return f, err
}
return f, nil
}
func runCode(f *os.File) ([]byte, error) {
cmd := exec.Command("go", "run", f.Name())
return cmd.CombinedOutput()
}
func runCodeHandler(w http.ResponseWriter, r *http.Request) {
code, err := ioutil.ReadAll(r.Body)
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
//fmt.Println(string(code))
res, err := Go.Eval(string(code))
if err != nil {
http.Error(w, string(res), http.StatusNotAcceptable)
return
}
w.Write(res)
}
func homePageHandler(w http.ResponseWriter, r *http.Request) {
homePageTemplate.Execute(w, nil)
}
var homePageTemplate = template.Must(template.New("homepage").Parse(homePageTemplateStr))
func main() {
addr, port := "localhost", 8000
fmt.Printf("running on %s:%d\n", addr, port)
http.HandleFunc("/run", runCodeHandler)
http.HandleFunc("/", homePageHandler)
err := http.ListenAndServe(fmt.Sprintf("%s:%d", addr, port), nil)
if err != nil {
log.Fatal(err)
}
}
const homePageTemplateStr = `
<!doctype html>
<html>
<head>
<title>lingua evalia</title>
<meta charset="utf-8" />
<style type="text/css">
#code {
border: none;
}
</style>
</head>
<body>
<textarea id="code" rows="20" cols="80">package main
import (
"fmt"
)
func main() {
fmt.Println("Hello, World!")
}
</textarea>
<pre id="result"></pre>
<script>
var codeEl = document.getElementById("code");
var resultEl = document.getElementById("result");
codeEl.onkeydown = function(ev) {
if (ev.ctrlKey && ev.keyCode == 13) {
resultEl.textContent = "";
sendCode(codeEl.value, function(result) {
resultEl.textContent = result;
});
}
}
function sendCode(code, cb) {
var xhr = new XMLHttpRequest();
xhr.open("POST", "/run");
xhr.onreadystatechange = function(ev) {
if (xhr.readyState == XMLHttpRequest.DONE) {
cb(xhr.response);
}
};
xhr.send(code);
}
</script>
</body>
</html>
`
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