R/utils.R

Defines functions wrapFunctionLabel URLencode writeUTF8 srcfilecopy makeCall sourceUTF8 tryNativeEncoding readUTF8 checkEncoding setServerInfo serverInfo stopWithCondition isTruthy dotloop cancelOutput req need validate reactiveStop safeError columnToRowData cachedFuncWithFile formatNoSci srcFileOfRef showcaseModeOfReq showcaseModeOfQuerystring srcrefFromShinyCall checkAsIs commaToRange getExists grep2 dataTablesJSON registerDebugHook shinyDeprecated shinyCallingHandlers assignNestedList parseQueryString installExprFunction exprToFunction makeFunction getContentType download isWindows resolve dirExists find.file.ci file.exists.ci file.path.ci list2env2 sortByName mergeVectors asNamedVector anyUnnamed anyNamed dropNullsOrEmpty nullOrEmpty dropNulls `%.%` `%AND%` `%OR%` isWholeNum p_randomInt randomInt p_sample p_runif withPrivateSeed withTemporary repeatable

Documented in exprToFunction installExprFunction isTruthy need parseQueryString repeatable req safeError serverInfo shinyDeprecated validate

#' @include globals.R
#' @include map.R
NULL

#' Make a random number generator repeatable
#'
#' Given a function that generates random data, returns a wrapped version of
#' that function that always uses the same seed when called. The seed to use can
#' be passed in explicitly if desired; otherwise, a random number is used.
#'
#' @param rngfunc The function that is affected by the R session's seed.
#' @param seed The seed to set every time the resulting function is called.
#' @return A repeatable version of the function that was passed in.
#'
#' @note When called, the returned function attempts to preserve the R session's
#'   current seed by snapshotting and restoring
#'   \code{\link[base]{.Random.seed}}.
#'
#' @examples
#' rnormA <- repeatable(rnorm)
#' rnormB <- repeatable(rnorm)
#' rnormA(3)  # [1]  1.8285879 -0.7468041 -0.4639111
#' rnormA(3)  # [1]  1.8285879 -0.7468041 -0.4639111
#' rnormA(5)  # [1]  1.8285879 -0.7468041 -0.4639111 -1.6510126 -1.4686924
#' rnormB(5)  # [1] -0.7946034  0.2568374 -0.6567597  1.2451387 -0.8375699
#' @export
repeatable <- function(rngfunc, seed = stats::runif(1, 0, .Machine$integer.max)) {
  force(seed)

  function(...) {
    # When we exit, restore the seed to its original state
    if (exists('.Random.seed', where=globalenv())) {
      currentSeed <- get('.Random.seed', pos=globalenv())
      on.exit(assign('.Random.seed', currentSeed, pos=globalenv()))
    }
    else {
      on.exit(rm('.Random.seed', pos=globalenv()))
    }

    set.seed(seed)

    rngfunc(...)
  }
}

# Temporarily set x in env to value, evaluate expr, and
# then restore x to its original state
withTemporary <- function(env, x, value, expr, unset = FALSE) {

  if (exists(x, envir = env, inherits = FALSE)) {
    oldValue <- get(x, envir = env, inherits = FALSE)
    on.exit(
      assign(x, oldValue, envir = env, inherits = FALSE),
      add = TRUE)
  } else {
    on.exit(
      rm(list = x, envir = env, inherits = FALSE),
      add = TRUE
    )
  }

  if (!missing(value) && !isTRUE(unset))
    assign(x, value, envir = env, inherits = FALSE)
  else {
    if (exists(x, envir = env, inherits = FALSE))
      rm(list = x, envir = env, inherits = FALSE)
  }
  force(expr)
}

.globals$ownSeed <- NULL
# Evaluate an expression using Shiny's own private stream of
# randomness (not affected by set.seed).
withPrivateSeed <- function(expr) {
  withTemporary(.GlobalEnv, ".Random.seed",
    .globals$ownSeed, unset=is.null(.globals$ownSeed), {
      tryCatch({
        expr
      }, finally = {
        .globals$ownSeed <- getExists('.Random.seed', 'numeric', globalenv())
      })
    }
  )
}

# a homemade version of set.seed(NULL) for backward compatibility with R 2.15.x
reinitializeSeed <- if (getRversion() >= '3.0.0') {
  function() set.seed(NULL)
} else function() {
  if (exists('.Random.seed', globalenv()))
    rm(list = '.Random.seed', pos = globalenv())
  stats::runif(1)  # generate any random numbers so R can reinitialize the seed
}

# Version of runif that runs with private seed
p_runif <- function(...) {
  withPrivateSeed(stats::runif(...))
}

# Version of sample that runs with private seed
p_sample <- function(...) {
  withPrivateSeed(sample(...))
}

# Return a random integral value in the range [min, max).
# If only one argument is passed, then min=0 and max=argument.
randomInt <- function(min, max) {
  if (missing(max)) {
    max <- min
    min <- 0
  }
  if (min < 0 || max <= min)
    stop("Invalid min/max values")

  min + sample(max-min, 1)-1
}

p_randomInt <- function(...) {
  withPrivateSeed(randomInt(...))
}

isWholeNum <- function(x, tol = .Machine$double.eps^0.5) {
  abs(x - round(x)) < tol
}

`%OR%` <- function(x, y) {
  if (is.null(x) || isTRUE(is.na(x)))
    y
  else
    x
}

`%AND%` <- function(x, y) {
  if (!is.null(x) && !is.na(x))
    if (!is.null(y) && !is.na(y))
      return(y)
  return(NULL)
}

`%.%` <- function(x, y) {
  paste(x, y, sep='')
}

# Given a vector or list, drop all the NULL items in it
dropNulls <- function(x) {
  x[!vapply(x, is.null, FUN.VALUE=logical(1))]
}

nullOrEmpty <- function(x) {
  is.null(x) || length(x) == 0
}
# Given a vector or list, drop all the NULL items in it
dropNullsOrEmpty <- function(x) {
  x[!vapply(x, nullOrEmpty, FUN.VALUE=logical(1))]
}

# Given a vector/list, return TRUE if any elements are named, FALSE otherwise.
anyNamed <- function(x) {
  # Zero-length vector
  if (length(x) == 0) return(FALSE)

  nms <- names(x)

  # List with no name attribute
  if (is.null(nms)) return(FALSE)

  # List with name attribute; check for any ""
  any(nzchar(nms))
}

# Given a vector/list, return TRUE if any elements are unnamed, FALSE otherwise.
anyUnnamed <- function(x) {
  # Zero-length vector
  if (length(x) == 0) return(FALSE)

  nms <- names(x)

  # List with no name attribute
  if (is.null(nms)) return(TRUE)

  # List with name attribute; check for any ""
  any(!nzchar(nms))
}


# Given a vector/list, returns a named vector (the labels will be blank).
asNamedVector <- function(x) {
  if (!is.null(names(x)))
    return(x)

  names(x) <- rep.int("", length(x))
  x
}

# Given two named vectors, join them together, and keep only the last element
# with a given name in the resulting vector. If b has any elements with the same
# name as elements in a, the element in a is dropped. Also, if there are any
# duplicated names in a or b, only the last one with that name is kept.
mergeVectors <- function(a, b) {
  if (anyUnnamed(a) || anyUnnamed(b)) {
    stop("Vectors must be either NULL or have names for all elements")
  }

  x <- c(a, b)
  drop_idx <- duplicated(names(x), fromLast = TRUE)
  x[!drop_idx]
}

# Sort a vector by the names of items. If there are multiple items with the
# same name, preserve the original order of those items. For empty
# vectors/lists/NULL, return the original value.
sortByName <- function(x) {
  if (anyUnnamed(x))
    stop("All items must be named")

  # Special case for empty vectors/lists, and NULL
  if (length(x) == 0)
    return(x)

  x[order(names(x))]
}

# Wrapper around list2env with a NULL check. In R <3.2.0, if an empty unnamed
# list is passed to list2env(), it errors. But an empty named list is OK. For
# R >=3.2.0, this wrapper is not necessary.
list2env2 <- function(x, ...) {
  # Ensure that zero-length lists have a name attribute
   if (length(x) == 0)
    attr(x, "names") <- character(0)

  list2env(x, ...)
}

# Combine dir and (file)name into a file path. If a file already exists with a
# name differing only by case, then use it instead.
file.path.ci <- function(...) {
  result <- find.file.ci(...)
  if (!is.null(result))
    return(result)

  # If not found, return the file path that was given to us.
  return(file.path(...))
}

# Does a particular file exist? Case-insensitive for filename, case-sensitive
# for path (on platforms with case-sensitive file system).
file.exists.ci <- function(...) {
  !is.null(find.file.ci(...))
}

# Look for a file, case-insensitive for filename, case-sensitive for path (on
# platforms with case-sensitive filesystem). If found, return the path to the
# file, with the correct case. If not found, return NULL.
find.file.ci <- function(...) {
  default <- file.path(...)
  if (length(default) > 1)
    stop("find.file.ci can only check for one file at a time.")
  if (file.exists(default))
    return(default)

  dir <- dirname(default)
  name <- basename(default)

  # If we got here, then we'll check for a directory with the exact case, and a
  # name with any case.
  all_files <- list.files(dir, all.files=TRUE, full.names=TRUE,
                          include.dirs=TRUE)
  match_idx <- tolower(name) == tolower(basename(all_files))
  matches <- all_files[match_idx]
  if (length(matches) == 0)
    return(NULL)

  return(matches[1])
}

# The function base::dir.exists was added in R 3.2.0, but for backward
# compatibility we need to add this function
dirExists <- function(paths) {
  file.exists(paths) & file.info(paths)$isdir
}

# Attempt to join a path and relative path, and turn the result into a
# (normalized) absolute path. The result will only be returned if it is an
# existing file/directory and is a descendant of dir.
#
# Example:
# resolve("/Users/jcheng", "shiny")  # "/Users/jcheng/shiny"
# resolve("/Users/jcheng", "./shiny")  # "/Users/jcheng/shiny"
# resolve("/Users/jcheng", "shiny/../shiny/")  # "/Users/jcheng/shiny"
# resolve("/Users/jcheng", ".")  # NULL
# resolve("/Users/jcheng", "..")  # NULL
# resolve("/Users/jcheng", "shiny/..")  # NULL
resolve <- function(dir, relpath) {
  abs.path <- file.path(dir, relpath)
  if (!file.exists(abs.path))
    return(NULL)
  abs.path <- normalizePath(abs.path, winslash='/', mustWork=TRUE)
  dir <- normalizePath(dir, winslash='/', mustWork=TRUE)
  # trim the possible trailing slash under Windows (#306)
  if (isWindows()) dir <- sub('/$', '', dir)
  if (nchar(abs.path) <= nchar(dir) + 1)
    return(NULL)
  if (substr(abs.path, 1, nchar(dir)) != dir ||
      substr(abs.path, nchar(dir)+1, nchar(dir)+1) != '/') {
    return(NULL)
  }
  return(abs.path)
}

isWindows <- function() .Platform$OS.type == 'windows'

# This is a wrapper for download.file and has the same interface.
# The only difference is that, if the protocol is https, it changes the
# download settings, depending on platform.
download <- function(url, ...) {
  # First, check protocol. If http or https, check platform:
  if (grepl('^https?://', url)) {

    # Check whether we are running R 3.2
    isR32 <- getRversion() >= "3.2"

    # Windows
    if (.Platform$OS.type == "windows") {

      if (isR32) {
        method <- "wininet"
      } else {

        # If we directly use setInternet2, R CMD CHECK gives a Note on Mac/Linux
        seti2 <- `::`(utils, 'setInternet2')

        # Check whether we are already using internet2 for internal
        internet2_start <- seti2(NA)

        # If not then temporarily set it
        if (!internet2_start) {
          # Store initial settings, and restore on exit
          on.exit(suppressWarnings(seti2(internet2_start)))

          # Needed for https. Will get warning if setInternet2(FALSE) already run
          # and internet routines are used. But the warnings don't seem to matter.
          suppressWarnings(seti2(TRUE))
        }

        method <- "internal"
      }

      # download.file will complain about file size with something like:
      #       Warning message:
      #         In download.file(url, ...) : downloaded length 19457 != reported length 200
      # because apparently it compares the length with the status code returned (?)
      # so we supress that
      suppressWarnings(utils::download.file(url, method = method, ...))

    } else {
      # If non-Windows, check for libcurl/curl/wget/lynx, then call download.file with
      # appropriate method.

      if (isR32 && capabilities("libcurl")) {
        method <- "libcurl"
      } else if (nzchar(Sys.which("wget")[1])) {
        method <- "wget"
      } else if (nzchar(Sys.which("curl")[1])) {
        method <- "curl"

        # curl needs to add a -L option to follow redirects.
        # Save the original options and restore when we exit.
        orig_extra_options <- getOption("download.file.extra")
        on.exit(options(download.file.extra = orig_extra_options))

        options(download.file.extra = paste("-L", orig_extra_options))

      } else if (nzchar(Sys.which("lynx")[1])) {
        method <- "lynx"
      } else {
        stop("no download method found")
      }

      utils::download.file(url, method = method, ...)
    }

  } else {
    utils::download.file(url, ...)
  }
}

getContentType <- function(file, defaultType = 'application/octet-stream') {
  subtype <- ifelse(grepl('[.]html?$', file), 'charset=UTF-8', '')
  mime::guess_type(file, unknown = defaultType, subtype = subtype)
}

# Create a zero-arg function from a quoted expression and environment
# @examples
# makeFunction(body=quote(print(3)))
makeFunction <- function(args = pairlist(), body, env = parent.frame()) {
  eval(call("function", args, body), env)
}

#' Convert an expression to a function
#'
#' This is to be called from another function, because it will attempt to get
#' an unquoted expression from two calls back.
#'
#' If expr is a quoted expression, then this just converts it to a function.
#' If expr is a function, then this simply returns expr (and prints a
#'   deprecation message).
#' If expr was a non-quoted expression from two calls back, then this will
#'   quote the original expression and convert it to a function.
#
#' @param expr A quoted or unquoted expression, or a function.
#' @param env The desired environment for the function. Defaults to the
#'   calling environment two steps back.
#' @param quoted Is the expression quoted?
#'
#' @examples
#' # Example of a new renderer, similar to renderText
#' # This is something that toolkit authors will do
#' renderTriple <- function(expr, env=parent.frame(), quoted=FALSE) {
#'   # Convert expr to a function
#'   func <- shiny::exprToFunction(expr, env, quoted)
#'
#'   function() {
#'     value <- func()
#'     paste(rep(value, 3), collapse=", ")
#'   }
#' }
#'
#'
#' # Example of using the renderer.
#' # This is something that app authors will do.
#' values <- reactiveValues(A="text")
#'
#' \dontrun{
#' # Create an output object
#' output$tripleA <- renderTriple({
#'   values$A
#' })
#' }
#'
#' # At the R console, you can experiment with the renderer using isolate()
#' tripleA <- renderTriple({
#'   values$A
#' })
#'
#' isolate(tripleA())
#' # "text, text, text"
#' @export
exprToFunction <- function(expr, env=parent.frame(), quoted=FALSE) {
  if (!quoted) {
    expr <- eval(substitute(substitute(expr)), parent.frame())
  }

  # expr is a quoted expression
  makeFunction(body=expr, env=env)
}

#' Install an expression as a function
#'
#' Installs an expression in the given environment as a function, and registers
#' debug hooks so that breakpoints may be set in the function.
#'
#' This function can replace \code{exprToFunction} as follows: we may use
#' \code{func <- exprToFunction(expr)} if we do not want the debug hooks, or
#' \code{installExprFunction(expr, "func")} if we do. Both approaches create a
#' function named \code{func} in the current environment.
#'
#' @seealso Wraps \code{\link{exprToFunction}}; see that method's documentation
#'   for more documentation and examples.
#'
#' @param expr A quoted or unquoted expression
#' @param name The name the function should be given
#' @param eval.env The desired environment for the function. Defaults to the
#'   calling environment two steps back.
#' @param quoted Is the expression quoted?
#' @param assign.env The environment in which the function should be assigned.
#' @param label A label for the object to be shown in the debugger. Defaults to
#'   the name of the calling function.
#' @param wrappedWithLabel,..stacktraceon Advanced use only. For stack manipulation purposes; see
#'   \code{\link{stacktrace}}.
#' @export
installExprFunction <- function(expr, name, eval.env = parent.frame(2),
                                quoted = FALSE,
                                assign.env = parent.frame(1),
                                label = deparse(sys.call(-1)[[1]]),
                                wrappedWithLabel = TRUE,
                                ..stacktraceon = FALSE) {
  if (!quoted) {
    quoted <- TRUE
    expr <- eval(substitute(substitute(expr)), parent.frame())
  }

  func <- exprToFunction(expr, eval.env, quoted)
  if (length(label) > 1) {
    # Just in case the deparsed code is more complicated than we imagine. If we
    # have a label with length > 1 it causes warnings in wrapFunctionLabel.
    label <- paste0(label, collapse = "\n")
  }
  if (wrappedWithLabel) {
    func <- wrapFunctionLabel(func, label, ..stacktraceon = ..stacktraceon)
  } else {
    registerDebugHook(name, assign.env, label)
  }
  assign(name, func, envir = assign.env)
}

#' Parse a GET query string from a URL
#'
#' Returns a named list of key-value pairs.
#'
#' @param str The query string. It can have a leading \code{"?"} or not.
#' @param nested Whether to parse the query string of as a nested list when it
#'   contains pairs of square brackets \code{[]}. For example, the query
#'   \samp{a[i1][j1]=x&b[i1][j1]=y&b[i2][j1]=z} will be parsed as \code{list(a =
#'   list(i1 = list(j1 = 'x')), b = list(i1 = list(j1 = 'y'), i2 = list(j1 =
#'   'z')))} when \code{nested = TRUE}, and \code{list(`a[i1][j1]` = 'x',
#'   `b[i1][j1]` = 'y', `b[i2][j1]` = 'z')} when \code{nested = FALSE}.
#' @export
#' @examples
#' parseQueryString("?foo=1&bar=b%20a%20r")
#'
#' \dontrun{
#' # Example of usage within a Shiny app
#' function(input, output, session) {
#'
#'   output$queryText <- renderText({
#'     query <- parseQueryString(session$clientData$url_search)
#'
#'     # Ways of accessing the values
#'     if (as.numeric(query$foo) == 1) {
#'       # Do something
#'     }
#'     if (query[["bar"]] == "targetstring") {
#'       # Do something else
#'     }
#'
#'     # Return a string with key-value pairs
#'     paste(names(query), query, sep = "=", collapse=", ")
#'   })
#' }
#' }
#'
parseQueryString <- function(str, nested = FALSE) {
  if (is.null(str) || nchar(str) == 0)
    return(list())

  # Remove leading ?
  if (substr(str, 1, 1) == '?')
    str <- substr(str, 2, nchar(str))

  pairs <- strsplit(str, '&', fixed = TRUE)[[1]]
  # Drop any empty items (if there's leading/trailing/consecutive '&' chars)
  pairs <- pairs[pairs != ""]
  pairs <- strsplit(pairs, '=', fixed = TRUE)

  keys   <- vapply(pairs, function(x) x[1], FUN.VALUE = character(1))
  values <- vapply(pairs, function(x) x[2], FUN.VALUE = character(1))
  # Replace NA with '', so they don't get converted to 'NA' by URLdecode
  values[is.na(values)] <- ''

  # Convert "+" to " ", since URLdecode doesn't do it
  keys   <- gsub('+', ' ', keys,   fixed = TRUE)
  values <- gsub('+', ' ', values, fixed = TRUE)

  keys   <- URLdecode(keys)
  values <- URLdecode(values)

  res <- stats::setNames(as.list(values), keys)
  if (!nested) return(res)

  # Make a nested list from a query of the form ?a[1][1]=x11&a[1][2]=x12&...
  for (i in grep('\\[.+\\]', keys)) {
    k <- strsplit(keys[i], '[][]')[[1L]]  # split by [ or ]
    res <- assignNestedList(res, k[k != ''], values[i])
    res[[keys[i]]] <- NULL    # remove res[['a[1][1]']]
  }
  res
}

# Assign value to the bottom element of the list x using recursive indices idx
assignNestedList <- function(x = list(), idx, value) {
  for (i in seq_along(idx)) {
    sub <- idx[seq_len(i)]
    if (is.null(x[[sub]])) x[[sub]] <- list()
  }
  x[[idx]] <- value
  x
}

# decide what to do in case of errors; it is customizable using the shiny.error
# option (e.g. we can set options(shiny.error = recover))
#' @include conditions.R
shinyCallingHandlers <- function(expr) {
  withCallingHandlers(captureStackTraces(expr),
    error = function(e) {
      # Don't intercept shiny.silent.error (i.e. validation errors)
      if (inherits(e, "shiny.silent.error"))
        return()

      handle <- getOption('shiny.error')
      if (is.function(handle)) handle()
    }
  )
}

#' Print message for deprecated functions in Shiny
#'
#' To disable these messages, use \code{options(shiny.deprecation.messages=FALSE)}.
#'
#' @param new Name of replacement function.
#' @param msg Message to print. If used, this will override the default message.
#' @param old Name of deprecated function.
#' @param version The last version of Shiny before the item was deprecated.
#' @keywords internal
shinyDeprecated <- function(new=NULL, msg=NULL,
                            old=as.character(sys.call(sys.parent()))[1L],
                            version = NULL) {

  if (getOption("shiny.deprecation.messages") %OR% TRUE == FALSE)
    return(invisible())

  if (is.null(msg)) {
    msg <- paste(old, "is deprecated.")
    if (!is.null(new)) {
      msg <- paste(msg, "Please use", new, "instead.",
        "To disable this message, run options(shiny.deprecation.messages=FALSE)")
    }
  }

  if (!is.null(version)) {
    msg <- paste0(msg, " (Last used in version ", version, ")")
  }

  # Similar to .Deprecated(), but print a message instead of warning
  message(msg)
}

#' Register a function with the debugger (if one is active).
#'
#' Call this function after exprToFunction to give any active debugger a hook
#' to set and clear breakpoints in the function. A debugger may implement
#' registerShinyDebugHook to receive callbacks when Shiny functions are
#' instantiated at runtime.
#'
#' @param name Name of the field or object containing the function.
#' @param where The reference object or environment containing the function.
#' @param label A label to display on the function in the debugger.
#' @noRd
registerDebugHook <- function(name, where, label) {
  if (exists("registerShinyDebugHook", mode = "function")) {
    registerShinyDebugHook <- get("registerShinyDebugHook", mode = "function")
    params <- new.env(parent = emptyenv())
    params$name <- name
    params$where <- where
    params$label <- label
    registerShinyDebugHook(params)
  }
}

Callbacks <- R6Class(
  'Callbacks',
  portable = FALSE,
  class = FALSE,
  public = list(
    .nextId = integer(0),
    .callbacks = 'Map',

    initialize = function() {
      # NOTE: we avoid using '.Machine$integer.max' directly
      # as R 3.3.0's 'radixsort' could segfault when sorting
      # an integer vector containing this value
      .nextId <<- as.integer(.Machine$integer.max - 1L)
      .callbacks <<- Map$new()
    },
    register = function(callback) {
      id <- as.character(.nextId)
      .nextId <<- .nextId - 1L
      .callbacks$set(id, callback)
      return(function() {
        .callbacks$remove(id)
      })
    },
    invoke = function(..., onError=NULL, ..stacktraceon = FALSE) {
      # Ensure that calls are invoked in the order that they were registered
      keys <- as.character(sort(as.integer(.callbacks$keys()), decreasing = TRUE))
      callbacks <- .callbacks$mget(keys)

      for (callback in callbacks) {
        if (is.null(onError)) {
          if (..stacktraceon) {
            ..stacktraceon..(callback(...))
          } else {
            callback(...)
          }
        } else {
          tryCatch(
            captureStackTraces(
              if (..stacktraceon)
                ..stacktraceon..(callback(...))
              else
                callback(...)
            ),
            error = onError
          )
        }
      }
    },
    count = function() {
      .callbacks$size()
    }
  )
)

# convert a data frame to JSON as required by DataTables request
dataTablesJSON <- function(data, req) {
  n <- nrow(data)
  # DataTables requests were sent via POST
  params <- URLdecode(rawToChar(req$rook.input$read()))
  q <- parseQueryString(params, nested = TRUE)
  ci <- q$search[['caseInsensitive']] == 'true'

  # data may have been replaced/updated in the new table while the Ajax request
  # from the previous table is still on its way, so it is possible that the old
  # request asks for more columns than the current data, in which case we should
  # discard this request and return empty data; the next Ajax request from the
  # new table will retrieve the correct number of columns of data
  if (length(q$columns) != ncol(data)) {
    res <- toJSON(list(
      draw = as.integer(q$draw),
      recordsTotal = n,
      recordsFiltered = 0,
      data = NULL
    ))
    return(httpResponse(200, 'application/json', enc2utf8(res)))
  }

  # global searching
  i <- seq_len(n)
  if (length(q$search[['value']]) && q$search[['value']] != '') {
    i0 <- apply(data, 2, function(x) {
      grep2(q$search[['value']], as.character(x),
            fixed = q$search[['regex']] == 'false', ignore.case = ci)
    })
    i <- intersect(i, unique(unlist(i0)))
  }

  # search by columns
  if (length(i)) for (j in names(q$columns)) {
    col <- q$columns[[j]]
    # if the j-th column is not searchable or the search string is "", skip it
    if (col[['searchable']] != 'true') next
    if ((k <- col[['search']][['value']]) == '') next
    j <- as.integer(j)
    dj <- data[, j + 1]
    r  <- commaToRange(k)
    ij <- if (length(r) == 2 && is.numeric(dj)) {
      which(dj >= r[1] & dj <= r[2])
    } else {
      grep2(k, as.character(dj), fixed = col[['search']][['regex']] == 'false',
            ignore.case = ci)
    }
    i <- intersect(ij, i)
    if (length(i) == 0) break
  }
  if (length(i) != n) data <- data[i, , drop = FALSE]

  # sorting
  oList <- list()
  for (ord in q$order) {
    k <- ord[['column']]  # which column to sort
    d <- ord[['dir']]     # direction asc/desc
    if (q$columns[[k]][['orderable']] != 'true') next
    col <- data[, as.integer(k) + 1]
    oList[[length(oList) + 1]] <- (if (d == 'asc') identity else `-`)(
      if (is.numeric(col)) col else xtfrm(col)
    )
  }
  if (length(oList)) {
    i <- do.call(order, oList)
    data <- data[i, , drop = FALSE]
  }
  # paging
  if (q$length != '-1') {
    i <- seq(as.integer(q$start) + 1L, length.out = as.integer(q$length))
    i <- i[i <= nrow(data)]
    fdata <- data[i, , drop = FALSE]  # filtered data
  } else fdata <- data

  fdata <- unname(as.matrix(fdata))
  if (is.character(fdata) && q$escape != 'false') {
    if (q$escape == 'true') fdata <- htmlEscape(fdata) else {
      k <- as.integer(strsplit(q$escape, ',')[[1]])
      # use seq_len() in case escape = negative indices, e.g. c(-1, -5)
      for (j in seq_len(ncol(fdata))[k]) fdata[, j] <- htmlEscape(fdata[, j])
    }
  }

  res <- toJSON(list(
    draw = as.integer(q$draw),
    recordsTotal = n,
    recordsFiltered = nrow(data),
    data = fdata
  ))
  httpResponse(200, 'application/json', enc2utf8(res))
}

# when both ignore.case and fixed are TRUE, we use grep(ignore.case = FALSE,
# fixed = TRUE) to do lower-case matching of pattern on x
grep2 <- function(pattern, x, ignore.case = FALSE, fixed = FALSE, ...) {
  if (fixed && ignore.case) {
    pattern <- tolower(pattern)
    x <- tolower(x)
    ignore.case <- FALSE
  }
  # when the user types in the search box, the regular expression may not be
  # complete before it is sent to the server, in which case we do not search
  if (!fixed && inherits(try(grep(pattern, ''), silent = TRUE), 'try-error'))
    return(seq_along(x))
  grep(pattern, x, ignore.case = ignore.case, fixed = fixed, ...)
}

getExists <- function(x, mode, envir = parent.frame()) {
  if (exists(x, envir = envir, mode = mode, inherits = FALSE))
    get(x, envir = envir, mode = mode, inherits = FALSE)
}

# convert a string of the form "lower,upper" to c(lower, upper)
commaToRange <- function(string) {
  if (!grepl(',', string)) return()
  r <- strsplit(string, ',')[[1]]
  if (length(r) > 2) return()
  if (length(r) == 1) r <- c(r, '')  # lower,
  r <- as.numeric(r)
  if (is.na(r[1])) r[1] <- -Inf
  if (is.na(r[2])) r[2] <- Inf
  r
}

# for options passed to DataTables/Selectize/..., the options of the class AsIs
# will be evaluated as literal JavaScript code
checkAsIs <- function(options) {
  evalOptions <- if (length(options)) {
    nms <- names(options)
    if (length(nms) == 0L || any(nms == '')) stop("'options' must be a named list")
    i <- unlist(lapply(options, function(x) {
      is.character(x) && inherits(x, 'AsIs')
    }))
    if (any(i)) {
      # must convert to character, otherwise toJSON() turns it to an array []
      options[i] <- lapply(options[i], paste, collapse = '\n')
      nms[i]  # options of these names will be evaluated in JS
    }
  }
  list(options = options, eval = evalOptions)
}

srcrefFromShinyCall <- function(expr) {
  srcrefs <- attr(expr, "srcref")
  num_exprs <- length(srcrefs)
  if (num_exprs < 1)
    return(NULL)
  c(srcrefs[[1]][1], srcrefs[[1]][2],
    srcrefs[[num_exprs]][3], srcrefs[[num_exprs]][4],
    srcrefs[[1]][5], srcrefs[[num_exprs]][6])
}

# Indicates whether the given querystring should cause the associated request
# to be handled in showcase mode. Returns the showcase mode if set, or NULL
# if no showcase mode is set.
showcaseModeOfQuerystring <- function(querystring) {
  if (nchar(querystring) > 0) {
    qs <- parseQueryString(querystring)
    if (exists("showcase", where = qs)) {
      return(as.numeric(qs$showcase))
    }
  }
  return(NULL)
}

showcaseModeOfReq <- function(req) {
  showcaseModeOfQuerystring(req$QUERY_STRING)
}

# Returns (just) the filename containing the given source reference, or an
# empty string if the source reference doesn't include file information.
srcFileOfRef <- function(srcref) {
  fileEnv <- attr(srcref, "srcfile")
  # The 'srcfile' attribute should be a non-null environment containing the
  # variable 'filename', which gives the full path to the source file.
  if (!is.null(fileEnv) &&
      is.environment(fileEnv) &&
      exists("filename", where = fileEnv))
    basename(fileEnv[["filename"]])
  else
    ""
}

# Format a number without sci notation, and keep as many digits as possible (do
# we really need to go beyond 15 digits?)
formatNoSci <- function(x) {
  if (is.null(x)) return(NULL)
  format(x, scientific = FALSE, digits = 15)
}

# Returns a function that calls the given func and caches the result for
# subsequent calls, unless the given file's mtime changes.
cachedFuncWithFile <- function(dir, file, func, case.sensitive = FALSE) {
  dir <- normalizePath(dir, mustWork=TRUE)
  mtime <- NA
  value <- NULL
  function(...) {
    fname <- if (case.sensitive)
      file.path(dir, file)
    else
      file.path.ci(dir, file)

    now <- file.info(fname)$mtime
    if (!identical(mtime, now)) {
      value <<- func(fname, ...)
      mtime <<- now
    }
    value
  }
}

# turn column-based data to row-based data (mainly for JSON), e.g. data.frame(x
# = 1:10, y = 10:1) ==> list(list(x = 1, y = 10), list(x = 2, y = 9), ...)
columnToRowData <- function(data) {
  do.call(
    mapply, c(
      list(FUN = function(...) list(...), SIMPLIFY = FALSE, USE.NAMES = FALSE),
      as.list(data)
    )
  )
}

#' Declare an error safe for the user to see
#'
#' This should be used when you want to let the user see an error
#' message even if the default is to sanitize all errors. If you have an
#' error \code{e} and call \code{stop(safeError(e))}, then Shiny will
#' ignore the value of \code{getOption("shiny.sanitize.errors")} and always
#' display the error in the app itself.
#'
#' @param error Either an "error" object or a "character" object (string).
#' In the latter case, the string will become the message of the error
#' returned by \code{safeError}.
#'
#' @return An "error" object
#'
#' @details An error generated by \code{safeError} has priority over all
#' other Shiny errors. This can be dangerous. For example, if you have set
#' \code{options(shiny.sanitize.errors = TRUE)}, then by default all error
#' messages are omitted in the app, and replaced by a generic error message.
#' However, this does not apply to \code{safeError}: whatever you pass
#' through \code{error} will be displayed to the user. So, this should only
#' be used when you are sure that your error message does not contain any
#' sensitive information. In those situations, \code{safeError} can make
#' your users' lives much easier by giving them a hint as to where the
#' error occurred.
#'
#' @seealso \code{\link{shiny-options}}
#'
#' @examples
#' ## Only run examples in interactive R sessions
#' if (interactive()) {
#'
#' # uncomment the desired line to experiment with shiny.sanitize.errors
#' # options(shiny.sanitize.errors = TRUE)
#' # options(shiny.sanitize.errors = FALSE)
#'
#' # Define UI
#' ui <- fluidPage(
#'   textInput('number', 'Enter your favorite number from 1 to 10', '5'),
#'   textOutput('normalError'),
#'   textOutput('safeError')
#' )
#'
#' # Server logic
#' server <- function(input, output) {
#'   output$normalError <- renderText({
#'     number <- input$number
#'     if (number %in% 1:10) {
#'       return(paste('You chose', number, '!'))
#'     } else {
#'       stop(
#'         paste(number, 'is not a number between 1 and 10')
#'       )
#'     }
#'   })
#'   output$safeError <- renderText({
#'     number <- input$number
#'     if (number %in% 1:10) {
#'       return(paste('You chose', number, '!'))
#'     } else {
#'       stop(safeError(
#'         paste(number, 'is not a number between 1 and 10')
#'       ))
#'     }
#'   })
#' }
#'
#' # Complete app with UI and server components
#' shinyApp(ui, server)
#' }
#' @export
safeError <- function(error) {
  if (inherits(error, "character")) {
    error <- simpleError(error)
  }
  if (!inherits(error, "error")) {
    stop("The class of the `error` parameter must be either 'error' or 'character'")
  }
  class(error) <- c("shiny.custom.error", class(error))
  error
}

#***********************************************************************#
#**** Keep this function internal for now, may chnage in the future ****#
#***********************************************************************#
# #' Propagate an error through Shiny, but catch it before it throws
# #'
# #' Throws a type of exception that is caught by observers. When such an
# #' exception is triggered, all reactive links are broken. So, essentially,
# #' \code{reactiveStop()} behaves just like \code{stop()}, except that
# #' instead of ending the session, it is silently swalowed by Shiny.
# #'
# #' This function should be used when you want to disrupt the reactive
# #' links in a reactive chain, but do not want to end the session. For
# #' example, this enables you to disallow certain inputs, but get back
# #' to business as usual when valid inputs are re-entered.
# #' \code{reactiveStop} is also called internally by Shiny to create
# #' special errors, such as the ones generated by \code{\link{validate}()},
# #' \code{\link{req}()} and \code{\link{cancelOutput}()}.
# #'
# #' @param message An optional error message.
# #' @param class An optional class to add to the error.
# #' @export
# #' @examples
# #' ## Note: the breaking of the reactive chain that happens in the app
# #' ## below (when input$txt = 'bad' and input$allowBad = 'FALSE') is
# #' ## easily visualized with `showReactLog()`
# #'
# #' ## Only run examples in interactive R sessions
# #' if (interactive()) {
# #'
# #' ui <- fluidPage(
# #'   textInput('txt', 'Enter some text...'),
# #'   selectInput('allowBad', 'Allow the string \'bad\'?',
# #'               c('TRUE', 'FALSE'), selected = 'FALSE')
# #' )
# #'
# #' server <- function(input, output) {
# #'   val <- reactive({
# #'     if (!(as.logical(input$allowBad))) {
# #'       if (identical(input$txt, "bad")) {
# #'         reactiveStop()
# #'       }
# #'     }
## '   })
# #'
# #'   observe({
# #'     val()
# #'   })
# #' }
# #'
# #' shinyApp(ui, server)
# #' }
# #' @export
reactiveStop <- function(message = "", class = NULL) {
  stopWithCondition(c("shiny.silent.error", class), message)
}

#' Validate input values and other conditions
#'
#' For an output rendering function (e.g. \code{\link{renderPlot}()}), you may
#' need to check that certain input values are available and valid before you
#' can render the output. \code{validate} gives you a convenient mechanism for
#' doing so.
#'
#' The \code{validate} function takes any number of (unnamed) arguments, each of
#' which represents a condition to test. If any of the conditions represent
#' failure, then a special type of error is signaled which stops execution. If
#' this error is not handled by application-specific code, it is displayed to
#' the user by Shiny.
#'
#' An easy way to provide arguments to \code{validate} is to use the \code{need}
#' function, which takes an expression and a string; if the expression is
#' considered a failure, then the string will be used as the error message. The
#' \code{need} function considers its expression to be a failure if it is any of
#' the following:
#'
#' \itemize{
#'   \item{\code{FALSE}}
#'   \item{\code{NULL}}
#'   \item{\code{""}}
#'   \item{An empty atomic vector}
#'   \item{An atomic vector that contains only missing values}
#'   \item{A logical vector that contains all \code{FALSE} or missing values}
#'   \item{An object of class \code{"try-error"}}
#'   \item{A value that represents an unclicked \code{\link{actionButton}}}
#' }
#'
#' If any of these values happen to be valid, you can explicitly turn them to
#' logical values. For example, if you allow \code{NA} but not \code{NULL}, you
#' can use the condition \code{!is.null(input$foo)}, because \code{!is.null(NA)
#' == TRUE}.
#'
#' If you need validation logic that differs significantly from \code{need}, you
#' can create other validation test functions. A passing test should return
#' \code{NULL}. A failing test should return an error message as a
#' single-element character vector, or if the failure should happen silently,
#' \code{FALSE}.
#'
#' Because validation failure is signaled as an error, you can use
#' \code{validate} in reactive expressions, and validation failures will
#' automatically propagate to outputs that use the reactive expression. In
#' other words, if reactive expression \code{a} needs \code{input$x}, and two
#' outputs use \code{a} (and thus depend indirectly on \code{input$x}), it's
#' not necessary for the outputs to validate \code{input$x} explicitly, as long
#' as \code{a} does validate it.
#'
#' @param ... A list of tests. Each test should equal \code{NULL} for success,
#'   \code{FALSE} for silent failure, or a string for failure with an error
#'   message.
#' @param errorClass A CSS class to apply. The actual CSS string will have
#'   \code{shiny-output-error-} prepended to this value.
#' @export
#' @examples
#' ## Only run examples in interactive R sessions
#' if (interactive()) {
#'
#' ui <- fluidPage(
#'   checkboxGroupInput('in1', 'Check some letters', choices = head(LETTERS)),
#'   selectizeInput('in2', 'Select a state', choices = state.name),
#'   plotOutput('plot')
#' )
#'
#' server <- function(input, output) {
#'   output$plot <- renderPlot({
#'     validate(
#'       need(input$in1, 'Check at least one letter!'),
#'       need(input$in2 != '', 'Please choose a state.')
#'     )
#'     plot(1:10, main = paste(c(input$in1, input$in2), collapse = ', '))
#'   })
#' }
#'
#' shinyApp(ui, server)
#'
#' }
validate <- function(..., errorClass = character(0)) {
  results <- sapply(list(...), function(x) {
    # Detect NULL or NA
    if (is.null(x))
      return(NA_character_)
    else if (identical(x, FALSE))
      return("")
    else if (is.character(x))
      return(paste(as.character(x), collapse = "\n"))
    else
      stop("Unexpected validation result: ", as.character(x))
  })

  results <- stats::na.omit(results)
  if (length(results) == 0)
    return(invisible())

  # There may be empty strings remaining; these are message-less failures that
  # started as FALSE
  results <- results[nzchar(results)]
  reactiveStop(paste(results, collapse="\n"), c(errorClass, "validation"))
}

#' @param expr An expression to test. The condition will pass if the expression
#'   meets the conditions spelled out in Details.
#' @param message A message to convey to the user if the validation condition is
#'   not met. If no message is provided, one will be created using \code{label}.
#'   To fail with no message, use \code{FALSE} for the message.
#' @param label A human-readable name for the field that may be missing. This
#'   parameter is not needed if \code{message} is provided, but must be provided
#'   otherwise.
#' @export
#' @rdname validate
need <- function(expr, message = paste(label, "must be provided"), label) {

  force(message) # Fail fast on message/label both being missing

  if (!isTruthy(expr))
    return(message)
  else
    return(invisible(NULL))
}

#' Check for required values
#'
#' Ensure that values are available ("truthy"--see Details) before proceeding
#' with a calculation or action. If any of the given values is not truthy, the
#' operation is stopped by raising a "silent" exception (not logged by Shiny,
#' nor displayed in the Shiny app's UI).
#'
#' The \code{req} function was designed to be used in one of two ways. The first
#' is to call it like a statement (ignoring its return value) before attempting
#' operations using the required values:
#'
#' \preformatted{rv <- reactiveValues(state = FALSE)
#' r <- reactive({
#'   req(input$a, input$b, rv$state)
#'   # Code that uses input$a, input$b, and/or rv$state...
#' })}
#'
#' In this example, if \code{r()} is called and any of \code{input$a},
#' \code{input$b}, and \code{rv$state} are \code{NULL}, \code{FALSE}, \code{""},
#' etc., then the \code{req} call will trigger an error that propagates all the
#' way up to whatever render block or observer is executing.
#'
#' The second is to use it to wrap an expression that must be truthy:
#'
#' \preformatted{output$plot <- renderPlot({
#'   if (req(input$plotType) == "histogram") {
#'     hist(dataset())
#'   } else if (input$plotType == "scatter") {
#'     qplot(dataset(), aes(x = x, y = y))
#'   }
#' })}
#'
#' In this example, \code{req(input$plotType)} first checks that
#' \code{input$plotType} is truthy, and if so, returns it. This is a convenient
#' way to check for a value "inline" with its first use.
#'
#' \strong{Truthy and falsy values}
#'
#' The terms "truthy" and "falsy" generally indicate whether a value, when
#' coerced to a \code{\link{logical}}, is \code{TRUE} or \code{FALSE}. We use
#' the term a little loosely here; our usage tries to match the intuitive
#' notions of "Is this value missing or available?", or "Has the user provided
#' an answer?", or in the case of action buttons, "Has the button been
#' clicked?".
#'
#' For example, a \code{textInput} that has not been filled out by the user has
#' a value of \code{""}, so that is considered a falsy value.
#'
#' To be precise, \code{req} considers a value truthy \emph{unless} it is one
#' of:
#'
#' \itemize{
#'   \item{\code{FALSE}}
#'   \item{\code{NULL}}
#'   \item{\code{""}}
#'   \item{An empty atomic vector}
#'   \item{An atomic vector that contains only missing values}
#'   \item{A logical vector that contains all \code{FALSE} or missing values}
#'   \item{An object of class \code{"try-error"}}
#'   \item{A value that represents an unclicked \code{\link{actionButton}}}
#' }
#'
#' Note in particular that the value \code{0} is considered truthy, even though
#' \code{as.logical(0)} is \code{FALSE}.
#'
#' If the built-in rules for truthiness do not match your requirements, you can
#' always work around them. Since \code{FALSE} is falsy, you can simply provide
#' the results of your own checks to \code{req}:
#'
#' \code{req(input$a != 0)}
#'
#' \strong{Using \code{req(FALSE)}}
#'
#' You can use \code{req(FALSE)} (i.e. no condition) if you've already performed
#' all the checks you needed to by that point and just want to stop the reactive
#' chain now. There is no advantange to this, except perhaps ease of readibility
#' if you have a complicated condition to check for (or perhaps if you'd like to
#' divide your condition into nested \code{if} statements).
#'
#' \strong{Using \code{cancelOutput = TRUE}}
#'
#' When \code{req(..., cancelOutput = TRUE)} is used, the "silent" exception is
#' also raised, but it is treated slightly differently if one or more outputs are
#' currently being evaluated. In those cases, the reactive chain does not proceed
#' or update, but the output(s) are left is whatever state they happen to be in
#' (whatever was their last valid state).
#'
#' Note that this is always going to be the case if
#' this is used inside an output context (e.g. \code{output$txt <- ...}). It may
#' or may not be the case if it is used inside a non-output context (e.g.
#' \code{\link{reactive}}, \code{\link{observe}} or \code{\link{observeEvent}})
#' -- depending on whether or not there is an \code{output$...} that is triggered
#' as a result of those calls. See the examples below for concrete scenarios.
#'
#' @param ... Values to check for truthiness.
#' @param cancelOutput If \code{TRUE} and an output is being evaluated, stop
#'   processing as usual but instead of clearing the output, leave it in
#'   whatever state it happens to be in.
#' @param x An expression whose truthiness value we want to determine
#' @return The first value that was passed in.
#' @export
#' @examples
#' ## Only run examples in interactive R sessions
#' if (interactive()) {
#'   ui <- fluidPage(
#'     textInput('data', 'Enter a dataset from the "datasets" package', 'cars'),
#'     p('(E.g. "cars", "mtcars", "pressure", "faithful")'), hr(),
#'     tableOutput('tbl')
#'   )
#'
#'   server <- function(input, output) {
#'     output$tbl <- renderTable({
#'
#'       ## to require that the user types something, use: `req(input$data)`
#'       ## but better: require that input$data is valid and leave the last
#'       ## valid table up
#'       req(exists(input$data, "package:datasets", inherits = FALSE),
#'           cancelOutput = TRUE)
#'
#'       head(get(input$data, "package:datasets", inherits = FALSE))
#'     })
#'   }
#'
#'   shinyApp(ui, server)
#' }
req <- function(..., cancelOutput = FALSE) {
  dotloop(function(item) {
    if (!isTruthy(item)) {
      if (isTRUE(cancelOutput)) {
        cancelOutput()
      } else {
        reactiveStop(class = "validation")
      }
    }
  }, ...)

  if (!missing(..1))
    ..1
  else
    invisible()
}

#***********************************************************************#
#**** Keep this function internal for now, may chnage in the future ****#
#***********************************************************************#
# #' Cancel processing of the current output
# #'
# #' Signals an error that Shiny treats specially if an output is currently being
# #' evaluated. Execution will stop, but rather than clearing the output (as
# #' \code{\link{req}} does) or showing an error message (as \code{\link{stop}}
# #' does), the output simply remains unchanged.
# #'
# #' If \code{cancelOutput} is called in any non-output context (like in an
# #' \code{\link{observe}} or \code{\link{observeEvent}}), the effect is the same
# #' as \code{\link{req}(FALSE)}.
# #' @export
# #' @examples
# #' ## Only run examples in interactive R sessions
# #' if (interactive()) {
# #'
# #' # uncomment the desired line to experiment with cancelOutput() vs. req()
# #'
# #' ui <- fluidPage(
# #'   textInput('txt', 'Enter text'),
# #'   textOutput('check')
# #' )
# #'
# #' server <- function(input, output) {
# #'   output$check <- renderText({
# #'     # req(input$txt)
# #'     if (input$txt == 'hi') return('hi')
# #'     else if (input$txt == 'bye') return('bye')
# #'     # else cancelOutput()
# #'   })
# #' }
# #'
# #' shinyApp(ui, server)
# #' }
cancelOutput <- function() {
  reactiveStop(class = "shiny.output.cancel")
}

# Execute a function against each element of ..., but only evaluate each element
# after the previous element has been passed to fun_. The return value of fun_
# is discarded, and only invisible() is returned from dotloop.
#
# Can be used to facilitate short-circuit eval on dots.
dotloop <- function(fun_, ...) {
  for (i in 1:(nargs()-1)) {
    fun_(eval(as.symbol(paste0("..", i))))
  }
  invisible()
}

#' @export
#' @rdname req
isTruthy <- function(x) {
  if (inherits(x, 'try-error'))
    return(FALSE)

  if (!is.atomic(x))
    return(TRUE)

  if (is.null(x))
    return(FALSE)
  if (length(x) == 0)
    return(FALSE)
  if (all(is.na(x)))
    return(FALSE)
  if (is.character(x) && !any(nzchar(stats::na.omit(x))))
    return(FALSE)
  if (inherits(x, 'shinyActionButtonValue') && x == 0)
    return(FALSE)
  if (is.logical(x) && !any(stats::na.omit(x)))
    return(FALSE)

  return(TRUE)
}

# add class(es) to the error condition, which will be used as names of CSS
# classes, e.g. shiny-output-error shiny-output-error-validation
stopWithCondition <- function(class, message) {
  cond <- structure(
    list(message = message),
    class = c(class, 'error', 'condition')
  )
  stop(cond)
}

#' Collect information about the Shiny Server environment
#'
#' This function returns the information about the current Shiny Server, such as
#' its version, and whether it is the open source edition or professional
#' edition. If the app is not served through the Shiny Server, this function
#' just returns \code{list(shinyServer = FALSE)}.
#'
#' This function will only return meaningful data when using Shiny Server
#' version 1.2.2 or later.
#' @export
#' @return A list of the Shiny Server information.
serverInfo <- function() {
  .globals$serverInfo
}
.globals$serverInfo <- list(shinyServer = FALSE)

setServerInfo <- function(...) {
  infoOld <- serverInfo()
  infoNew <- list(...)
  infoOld[names(infoNew)] <- infoNew
  .globals$serverInfo <- infoOld
}

# assume file is encoded in UTF-8, but warn against BOM
checkEncoding <- function(file) {
  # skip *nix because its locale is normally UTF-8 based (e.g. en_US.UTF-8), and
  # *nix users have to make a conscious effort to save a file with an encoding
  # that is not UTF-8; if they choose to do so, we cannot do much about it
  # except sitting back and seeing them punished after they choose to escape a
  # world of consistency (falling back to getOption('encoding') will not help
  # because native.enc is also normally UTF-8 based on *nix)
  if (!isWindows()) return('UTF-8')
  size <- file.info(file)[, 'size']
  if (is.na(size)) stop('Cannot access the file ', file)
  # BOM is 3 bytes, so if the file contains BOM, it must be at least 3 bytes
  if (size < 3L) return('UTF-8')

  # check if there is a BOM character: this is also skipped on *nix, because R
  # on *nix simply ignores this meaningless character if present, but it hurts
  # on Windows
  if (identical(charToRaw(readChar(file, 3L, TRUE)), charToRaw('\UFEFF'))) {
    warning('You should not include the Byte Order Mark (BOM) in ', file, '. ',
            'Please re-save it in UTF-8 without BOM. See ',
            'http://shiny.rstudio.com/articles/unicode.html for more info.')
    return('UTF-8-BOM')
  }
  x <- readChar(file, size, useBytes = TRUE)
  if (is.na(iconv(x, 'UTF-8', 'UTF-8'))) {
    warning('The input file ', file, ' does not seem to be encoded in UTF8')
  }
  'UTF-8'
}

# read a file using UTF-8 and (on Windows) convert to native encoding if possible
readUTF8 <- function(file) {
  enc <- checkEncoding(file)
  file <- base::file(file, encoding = enc)
  on.exit(close(file), add = TRUE)
  x <- enc2utf8(readLines(file, warn = FALSE))
  tryNativeEncoding(x)
}

# if the UTF-8 string can be represented in the native encoding, use native encoding
tryNativeEncoding <- function(string) {
  if (!isWindows()) return(string)
  string2 <- enc2native(string)
  if (identical(enc2utf8(string2), string)) string2 else string
}

# similarly, try to source() a file with UTF-8
sourceUTF8 <- function(file, envir = globalenv()) {
  lines <- readUTF8(file)
  enc <- if (any(Encoding(lines) == 'UTF-8')) 'UTF-8' else 'unknown'
  src <- srcfilecopy(file, lines, isFile = TRUE)  # source reference info
  # oddly, parse(file) does not work when file contains multibyte chars that
  # **can** be encoded natively on Windows (might be a bug in base R); we
  # rewrite the source code in a natively encoded temp file and parse it in this
  # case (the source reference is still pointed to the original file, though)
  if (isWindows() && enc == 'unknown') {
    file <- tempfile(); on.exit(unlink(file), add = TRUE)
    writeLines(lines, file)
  }
  exprs <- try(parse(file, keep.source = FALSE, srcfile = src, encoding = enc))
  if (inherits(exprs, "try-error")) {
    diagnoseCode(file)
    stop("Error sourcing ", file)
  }

  # Wrap the exprs in first `{`, then ..stacktraceon..(). It's only really the
  # ..stacktraceon..() that we care about, but the `{` is needed to make that
  # possible.
  exprs <- makeCall(`{`, exprs)
  # Need to wrap exprs in a list because we want it treated as a single argument
  exprs <- makeCall(..stacktraceon.., list(exprs))

  eval(exprs, envir)
}

# @param func Name of function, in unquoted form
# @param args An evaluated list of unevaluated argument expressions
makeCall <- function(func, args) {
  as.call(c(list(substitute(func)), args))
}

# a workaround for https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=16264
srcfilecopy <- function(filename, lines, ...) {
  if (getRversion() > '3.2.2') return(base::srcfilecopy(filename, lines, ...))
  src <- base::srcfilecopy(filename, lines = '', ...)
  src$lines <- lines
  src
}

# write text as UTF-8
writeUTF8 <- function(text, ...) {
  text <- enc2utf8(text)
  writeLines(text, ..., useBytes = TRUE)
}

URLdecode <- decodeURIComponent
URLencode <- function(value, reserved = FALSE) {
  value <- enc2utf8(value)
  if (reserved) encodeURIComponent(value) else encodeURI(value)
}


# This function takes a name and function, and it wraps that function in a new
# function which calls the original function using the specified name. This can
# be helpful for profiling, because the specified name will show up on the stack
# trace.
wrapFunctionLabel <- function(func, name, ..stacktraceon = FALSE) {
  if (name == "name" || name == "func" || name == "relabelWrapper") {
    stop("Invalid name for wrapFunctionLabel: ", name)
  }
  assign(name, func, environment())
  registerDebugHook(name, environment(), name)

  relabelWrapper <- eval(substitute(
    function(...) {
      # This `f` gets renamed to the value of `name`. Note that it may not
      # print as the new name, because of source refs stored in the function.
      if (..stacktraceon)
        ..stacktraceon..(f(...))
      else
        f(...)
    },
    list(f = as.name(name))
  ))

  relabelWrapper
}


# This is a very simple mutable object which only stores one value
# (which we can set and get). Using this class is sometimes useful
# when communicating persistent changes across functions.
Mutable <- R6Class("Mutable",
  private = list(
    value = NULL
  ),
  public = list(
    set = function(value) { private$value <- value },
    get = function() { private$value }
  )
)
sheikhbarabas/shiny documentation built on May 29, 2019, 9:22 p.m.