Skip to content

Instantly share code, notes, and snippets.

@wch wch/remote_repl.R
Last active Aug 7, 2019

Embed
What would you like to do?
Remote R REPL app with httpuv
library(httpuv)
PORT <- 7000
app <- list(
call = function(req) {
page(req)
},
onWSOpen = function(ws) {
ws$onMessage(function(binary, message) {
on_message(ws, binary, message)
})
}
)
page <- function(req) {
wsUrl = paste(sep='',
'"',
"ws://",
ifelse(is.null(req$HTTP_HOST), req$SERVER_NAME, req$HTTP_HOST),
'"')
list(
status = 200L,
headers = list(
'Content-Type' = 'text/html'
),
body = sprintf('
<html>
<head>
<style type="text/css">
body {
font-size: 14px;
}
pre {
margin: 0
}
.user-input {
color: blue;
margin-top: 4px;
}
.user-input textarea {
color: blue;
vertical-align: top;
font-family: Courier;
font-size: 14px;
margin: 0;
border: 0;
padding: 0;
outline: none;
}
</style>
<script>
var ws = new WebSocket("ws://localhost:%s");
ws.onmessage = function(msg) {
var msgDiv = document.createElement("pre");
msgDiv.innerHTML = msg.data.replace(/&/g, "&amp;").replace(/\\</g, "&lt;");
document.getElementById("output").appendChild(msgDiv);
document.documentElement.scrollIntoView({behavior: "smooth", block: "end"});
}
function sendInput() {
var input = document.getElementById("input");
// Append the text
var msgDiv = document.createElement("pre");
msgDiv.setAttribute("class", "user-input");
msgDiv.innerHTML = "&gt; " + input.value.replace(/&/g, "&amp;").replace(/\\</g, "&lt;");
document.getElementById("output").appendChild(msgDiv);
if (input.value == "") {
// Don\'t try to eval empty line
return;
}
ws.send(input.value);
input.value = "";
}
</script>
</head>
<body>
<div id="output">
<pre>%s
</pre>
</div>
<pre class="user-input">&gt; <textarea rows=1 cols=100 id="input" autofocus></textarea>
</pre>
<script>
document.getElementById("input").addEventListener("keydown", function(event) {
if (event.key === "Enter") {
if (event.shiftKey) {
// Don\'t send if Shift is down. Only increase number of rows.
input.rows = input.rows + 1;
} else {
sendInput();
event.preventDefault();
}
}
});
</script>
</body>
</html>
', PORT, R.version.string
)
)
}
on_message <- function(ws, binary, message) {
result_txt <- capture.output({
tryCatch(
{
expr <- parse(text = message)
result <- withVisible(eval(expr, envir = .GlobalEnv))
if (result$visible == TRUE) {
print(result$value)
}
},
error = function(e) {
cat("Error: ", e$message)
}
)
})
result_txt <- paste(result_txt, collapse = "\n")
ws$send(result_txt)
}
startServer("0.0.0.0", PORT, app)
browseURL(sprintf("http://localhost:%s/", PORT))
# Things to try:
# trace(on_message, edit = TRUE)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.