R/mod_cass_regex_info.R

In giocomai/castarter: Content Analysis Starter Toolkit

#' Explain basics of how pattern matching works.
#'
#' @description A shiny Module.
#'
#' @param id,input,output,session Internal parameters for {shiny}.
#'
#' @noRd
#'
#' @importFrom shiny NS tagList
mod_cass_regex_info_ui <- function(id) {
  ns <- NS(id)
  tagList(
    shiny::actionLink(
      inputId = ns("show_regex_helpers"),
      label = "Pattern matching tips",
      icon = shiny::icon(name = "info")
    )
  )
}

#' cass_regex_info Server Functions
#'
#' @noRd
mod_cass_regex_info_server <- function(id) {
  moduleServer(id, function(input, output, session) {
    ns <- session$ns

    shiny::observeEvent(
      eventExpr = ns(input$show_regex_helpers),
      ignoreInit = TRUE,
      handlerExpr = {
        shiny::showModal(
          shiny::modalDialog(
            title = "How does pattern matching work here?",
            easyClose = TRUE,
            size = "xl",
            shiny::h2("The basics"),
            shiny::tags$ul(
              shiny::tags$li("Use comma-separated patterns for comparisons: e.g. searching for 'apple, orange' will match items that include either 'apple' or 'orange', and will report them separately in graphs."),
              shiny::tags$li("Use the `|` sign to combine patterns: e.g. searching for 'apple|pear, orange|lemon' will combine apple and pear (and orange and lemon) in results."),
              shiny::tags$li("By default, any match - not only full words - is counted: e.g. 'verb' would match also with 'proverb'. This can be useful, but requires some caution. For example, 'ukrain' would match 'ukraine', 'ukrainian', etc., which may or may not be desirable, depending on the use case."),
              shiny::tags$li("By default, pattern matching is not case sensitive: e.g. 'ukrain' and 'Ukrain' would give exactly the same results."),
            ),
            shiny::h2("Regular expressions"),
            shiny::p(
              "By default, this interface relies on regular expressions (also known as regex) in order to enable advanced pattern matching.",
              "For more information on supported expressions, ", shiny::a(href = "https://github.com/google/re2/wiki/Syntax", "see the documentation of the underlying library.")
            ),
            shiny::p("Here are a few examples of common use cases:"),
            shiny::tags$ul(
              shiny::tags$li("It is possible to match specific combinations. For example, if you want to match both 'russian' and 'russians', you can search for 'russian[s]?`, which indicates that the final 's' may or may not be present; 'russian|russians' would similarly work."),
              shiny::tags$li("In particular for languages with declensions, it may be important to consider all possible terminations, especially when combining words: for example, in 'коллективн[а-я]+ Запад', '[а-я]+' would capture none, one or more letters of the Cyrillic alphabet (the corresponding for Latin characters would be '[a-z]?'; other alphabets can be capptured with e.g. \\p{Cyrillic} or \\p{Greek})."),
              shiny::tags$li("If you rely on regex, be mindful that some selectors (e.g. '[[:alpha:]]' for any character or '\\b' for word boundary) refer specifically to ASCII characters and will not work as expected with non-ASCII characters such as some accented letters or non-Latin alphabets.")
            )
          )
        )
      }
    )
  })
}

## To be copied in the UI
# mod_cass_regex_info_ui("cass_regex_info_1")

## To be copied in the server
# mod_cass_regex_info_server("cass_regex_info_1")


cass_regex_info <- function() {
  ui <- shiny::fluidPage(
    mod_cass_regex_info_ui(id = "cass_regex_info_1")
  )

  server <- function(input, output, session) {
    mod_cass_regex_info_server("cass_regex_info_1")
  }
  shiny::shinyApp(ui, server)
}