scaffold_utils.R

slurp <- function(file) {
  paste(readLines(
    system.file(file, package = 'reactR')
  ), collapse = "\n")
}

# invoke file.edit in a way that will bind to the RStudio editor
# when running inside RStudio
fileEdit <- function(file) {
  fileEditFunc <- eval(parse(text = "file.edit"), envir = globalenv())
  fileEditFunc(file)
}

startsWith <- function(s1, s2) {
  substr(s1, 0, nchar(s2)) == s2
}

renderTemplateIter <- function(str, substitutions) {
  if (length(substitutions) == 0) return(str)
  output <- ""
  repeat {
    if (nchar(str) == 0) return(output)
    matched <- FALSE
    for (name in names(substitutions)) {
      placeholder <- paste0('${', name, '}')
      if (startsWith(str, placeholder)) {
        matched <- TRUE
        output <- paste0(output, substitutions[[name]])
        str <- substr(str, nchar(name)+4, nchar(str))
        break
      }
    }
    if (!matched) {
      output <- paste0(output, substr(str, 1, 1))
      str <- substr(str, 2, nchar(str))
    }
  }
  output
}

matches <- function(str, pat) {
  stopifnot(length(str) == 1)
  match <- gregexpr(pat, str)[[1]]
  if (any(match == -1)) return()
  df <- data.frame(
    start = match,
    end = match + attr(match, 'match.length') - 1
  )
  df[order(df$start),]
}

gfsub <- function(str, pat, func) {
  if (nchar(str) == 0) return(str)
  df <- matches(str, pat)
  output <- ""
  i <- 1
  repeat {
    if (nrow(df) == 0 && nchar(str) > i) {
      return(paste0(output, substr(str, i, nchar(str))))
    } else if (nrow(df) == 0) {
      return(output)
    } else {
      h <- head(df)
      output <- paste0(output, substr(str, i, h$start - 1))
      output <- paste0(output, func(substr(str, h$start, h$end)))
      i <- h$end + 1
      df <- tail(df, -1)
    }
  }
  output
}

renderTemplateGfsub <- function(str, substitutions) {
  gfsub(str, '\\$\\{\\w+\\}', function(placeholder) {
    substitutions[[substr(placeholder, 3, nchar(placeholder)-1)]]
  })
}

# Perform a series of pattern replacements on str.
# Example: renderTemplate("foo ${x} bar ${y} baz ${x}", list(x = 1, y = 2))
# Produces: "foo 1 bar 2 baz 1"
renderTemplate <- function(str, substitutions) {
  Reduce(function(str, name) {
    gsub(paste0("\\$\\{", name, "\\}"), substitutions[[name]], str)
  }, names(substitutions), str)
}

capitalize <- function(s) {
  gsub("^(.)", perl = TRUE, replacement = '\\U\\1', s)
}

toDepJSON <- function(npmPkgs) {
  if (is.null(npmPkgs)) {
    ""
  } else if (!length(names(npmPkgs))) {
    stop("Must specify npm package names in the names attributes of npmPkgs")
  } else {
    paste0(sprintf('"%s": "%s"', names(npmPkgs), npmPkgs), collapse = ",\n")
  }
}

# Wraps renderTemplate for convenient use from scaffold functions.
renderFile <- function(outputFile, templateFile, description = '', substitutions = list()) {
  if (!file.exists(outputFile)) {
    dir.create(dirname(outputFile), recursive = TRUE, showWarnings = FALSE)
    cat(renderTemplate(slurp(templateFile), substitutions), file = outputFile)
    message("Created ", description, " ", outputFile)
  } else {
    message(outputFile, " already exists")
  }
  outputFile
}

getPackage <- function() {
  if (!file.exists('DESCRIPTION')) {
    stop("You need to create a package to house your widget first!", call. = FALSE)
  }
  read.dcf('DESCRIPTION')[[1,"Package"]]
}