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# Example 1: running at top level. This works.
model_str1 <- "speed~dist"
model1 <- lm(formula=model_str1, data=cars)
stats::update(model1, y = TRUE)
#> 
#> Call:
#> lm(formula = model_str1, data = cars, y = TRUE)
#> 
#> Coefficients:
#> (Intercept)         dist  

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# This function recurses into `expr`, looking for `search_expr`. If it finds
# it, it will return `replace_expr`. Notably, `replace_expr` can contain rlang
# operators like `!!`, and perform rlang substitution on them.
modify_expr <- function(
  expr,
  search_expr,
  replace_expr
) {
  if (typeof(expr) != "language") {
    stop("modify_expr only works on language objects (AKA quoted expressions)!")

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# Test app for https://github.com/rstudio/shiny/pull/3666

# pkgload::load_all()

library(promises)
library(httpuv)
library(htmltools)
library(shiny)
library(later)
options(shiny.minified = FALSE)

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# The code below demonstrates that in R, growing a vector in a loop can be fast,
# as long as there is only reference to the object. When there's only one
# reference to the vector, R grows it in place (in most cases). However, if
# there are other references to the object, R must make a copy the object
# instead of growing it in place, leading to slower performance.

# =========================================================================
# Timing tests
# =========================================================================

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This is a test, v2!

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# Web REPL/console


# Note: 127.0.0.1 allows connections only from localhost. To listen on external
# ports, use 0.0.0.0.
web_repl <- function(host = "127.0.0.1", port = 8080) {
  library(httpuv)

  app <- list(
    call = function(req) {

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# @drob's version from https://twitter.com/drob/status/1501747414780239879
pluck_recursive <- function(lst, name) {
  if (is.list(lst)) {
    if (!is.null(lst[[name]])) {
      return(lst[[name]])
    }
    return(unname(unlist(purrr::map(lst, pluck_recursive, name))))
  }
}

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library(inline)
get_mtime <- cfunction(
  signature(filename = "character"),
  includes = "
    #include <time.h>
    #include <sys/stat.h>",
  body = '
    const char* path = CHAR(asChar(filename));
    struct stat attr;
    stat(path, &attr);

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# Demonstration of using ContextVars instead of global variables.

# Set to True for global mode, False for ContextVar mode
global_mode = False

# With a global variable, the result is: 1 2 3 3 3 3 3 3 3
# With a ContextVar, the result is:      1 2 3 1 2 3 1 2 3

import asyncio
import contextvars

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# This code uses later's C API to schedule callbacks as quickly as possible, and
# it tests if the callbacks execute in the same order that they are scheduled.
# In Docker on Mac, they sometimes do not.

docker run --rm -ti rocker/shiny /bin/bash
R
install.packages(c('cpp11', 'later', 'brio', 'callr', 'cli', 'decor', 'desc',
  'tibble', 'vctrs'))

library(cpp11)