From 5f8e8e33b14678414daddeb72fbc366e2114cb97 Mon Sep 17 00:00:00 2001
From: Artem Klevtsov <a.a.klevtsov@gmail.com>
Date: Fri, 12 Jul 2019 07:55:40 +0700
Subject: [PATCH 1/2] Move htmlwidgets to suggests (closes #18)

---
 DESCRIPTION | 19 +++++++++++++------
 R/widget.R  | 10 +++++++---
 R/zzz.R     |  1 -
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index b6f8bc3..b1c0a95 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -22,13 +22,20 @@ License: BSD_3_clause + file LICENSE
 LazyData: TRUE
 Depends: R (>= 3.3)
 Imports:
-    Rcpp (>= 0.12.2), stringi, RcppParallel,
-    htmlwidgets (>= 0.6),
-LinkingTo: Rcpp, RcppParallel
+    Rcpp (>= 0.12.2),
+    stringi,
+    RcppParallel
+LinkingTo:
+    Rcpp,
+    RcppParallel
 Suggests:
-    knitr (>= 1.12.3),testthat,
-    rmarkdown (>= 0.9.5),microbenchmark,
-    ggplot2, directlabels
+    htmlwidgets (>= 0.6),
+    knitr (>= 1.12.3),
+    testthat,
+    rmarkdown (>= 0.9.5),
+    microbenchmark,
+    ggplot2,
+    directlabels
 URL: https://github.com/qinwf/re2r/
 BugReports: https://github.com/qinwf/re2r/issues
 VignetteBuilder: knitr
diff --git a/R/widget.R b/R/widget.R
index 4175c47..ed3979d 100644
--- a/R/widget.R
+++ b/R/widget.R
@@ -34,11 +34,15 @@ remove_named = function(string){
 #' @export
 show_regex <- function(pattern, width = NULL, height = NULL) {
 
-    if (is.character(pattern)){
+    if (!requireNamespace("htmlwidgets", quietly = TRUE)) {
+        stop("'htmlwidgets' package is not installed.")
+    }
+
+    if (is.character(pattern)) {
         res = re2(pattern)
-    }else if (inherits(pattern,"re2c")) {
+    } else if (inherits(pattern,"re2c")) {
         res = pattern
-    } else if (is.list(pattern)){
+    } else if (is.list(pattern)) {
         return(show_regex(pattern[[1]], width, height))
     } else {
         stop("pattern is a string or a pre-compiled regular expression.")
diff --git a/R/zzz.R b/R/zzz.R
index 1c574bf..d26f5a8 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -32,7 +32,6 @@
 
 ##' @useDynLib re2r
 ##' @import Rcpp
-##' @import htmlwidgets
 ##' @importFrom stringi stri_enc_toutf8
 ##' @importFrom RcppParallel RcppParallelLibs
 NULL

From 57fbd025c7c18b759033f77f38d72b7e860dfb60 Mon Sep 17 00:00:00 2001
From: Artem Klevtsov <a.a.klevtsov@gmail.com>
Date: Fri, 12 Jul 2019 08:28:08 +0700
Subject: [PATCH 2/2] Skip test show_regex if htmlwidgets is not installed

---
 tests/testthat/test-show.R | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/testthat/test-show.R b/tests/testthat/test-show.R
index ffaf37f..d8f4215 100644
--- a/tests/testthat/test-show.R
+++ b/tests/testthat/test-show.R
@@ -1,6 +1,7 @@
 context("test show regex")
 
 test_that("test show_regex",{
+    skip_if_not_installed("htmlwidgets")
     show_regex(re2("(?P<testname>>this)( is)(?P<testname>>this)"))
     show_regex("show_regex")
     expect_error(show_regex(list()))