_common.R

# load shiny first to avoid any conflict messages later
library(shiny)

# Don't run apps when knitting
shinyApp <- function(...) {
  if (isTRUE(getOption("knitr.in.progress"))) {
    invisible()
  } else {
    shiny::shinyApp(...)
  }
}

knitr::opts_chunk$set(
  comment = "#>",
  collapse = TRUE,
  # cache = TRUE,
  fig.retina = 0.8, # figures are either vectors or 300 dpi diagrams
  dpi = 300,
  out.width = "70%",
  # fig.align = 'center',
  fig.width = 6,
  fig.asp = 0.618,  # 1 / phi
  fig.show = "hold",
  eval.after = 'fig.cap' # so captions can use link to demos
)

options(
  digits = 3,

  # Suppress crayon since it's falsely on in GHA
  crayon.enabled = FALSE,

  # Better rlang tracebacks
  rlang_trace_top_env = rlang::current_env()
)

# In final book can go up to 81
# http://oreillymedia.github.io/production-resources/styleguide/#code
# See preamble.tex for tweak that makes this work in pdf output
knitr::opts_chunk$set(width = 81)
options(width = 81)

# Reactive console simulation  -------------------------------------------------
# From https://github.com/rstudio/shiny/issues/2518#issuecomment-507408379
reactive_console_funs <- list(
  reactiveVal = function(value = NULL, label = NULL) {
    if (missing(label)) {
      call <- sys.call()
      label <- shiny:::rvalSrcrefToLabel(attr(call, "srcref", exact = TRUE))
    }

    rv <- shiny::reactiveVal(value, label)
    function(x) {
      if (missing(x)) {
        rv()
      } else {
        on.exit(shiny:::flushReact(), add = TRUE, after = FALSE)
        rv(x)
      }
    }
  },
  reactiveValues = function(...) {
    rv <- shiny::reactiveValues(...)
    class(rv) <- c("rv_flush_on_write", class(rv))
    rv
  },
  `$<-.rv_flush_on_write` = function(x, name, value) {
    on.exit(shiny:::flushReact(), add = TRUE, after = FALSE)
    NextMethod()
  },
  observe = function(...) {
    on.exit(shiny:::flushReact(), add = TRUE, after = FALSE)
    shiny::observe(...)
  }
)

# override shiny::reactiveConsole() with shims that work in knitr
reactiveConsole <- function(enabled = TRUE) {
  options(shiny.suppressMissingContextError = enabled)
  if (enabled) {
    attach(reactive_console_funs, name = "reactive_console", warn.conflicts = FALSE)
    vctrs::s3_register("base::$<-", "rv_flush_on_write")
  } else {
    detach("reactive_console")
  }
}

# Code extraction ---------------------------------------------------------

section_get <- function(path, name) {
  lines <- vroom::vroom_lines(path)
  start <- which(grepl(paste0("^\\s*#<< ", name), lines))

  if (length(start) == 0) {
    stop("Couldn't find '#<<", name, "'", call. = FALSE)
  }
  if (length(start) > 1) {
    stop("Found multiple '#<< ", name, "'", call. = FALSE)
  }

  # need to build stack of #<< #>> so we can have nested components

  end <- which(grepl("\\s*#>>", lines))
  end <- end[end > start]

  if (length(end) == 0) {
    stop("Couldn't find '#>>", call. = FALSE)
  }
  end <- end[[1]]

  lines[(start + 1):(end - 1)]
}

section_strip <- function(path) {
  lines <- vroom::vroom_lines(path)
  sections <- grepl("^#(>>|<<)", lines)
  lines[!sections]
}

# Errors ------------------------------------------------------------------

# Make error messages closer to base R
registerS3method("wrap", "error", envir = asNamespace("knitr"),
  function(x, options) {
    msg <- conditionMessage(x)

    call <- conditionCall(x)
    if (is.null(call)) {
      msg <- paste0("Error: ", msg)
    } else {
      msg <- paste0("Error in ", deparse(call)[[1]], ": ", msg)
    }

    msg <- error_wrap(msg)
    knitr:::msg_wrap(msg, "error", options)
  }
)

error_wrap <- function(x, width = getOption("width")) {
  lines <- strsplit(x, "\n", fixed = TRUE)[[1]]
  paste(strwrap(lines, width = width), collapse = "\n")
}