Fix nested groups calculation and add example to Readme

R/run_regex.R

   for (j in seq_len(nrow(inserts))) {
     if (inserts$i[j] == 0) next
     overlap <- filter(
-      inserts,
+      inserts[1:(j-1), ],
       i != 0,
-      start <= !!inserts$start[j] & end > !!inserts$end[j])
+      start <= !!inserts$start[j] & end >= !!inserts$end[j])
     inserts[j, 'pad'] <- inserts$pad[j] + nrow(overlap)
   }
   inserts <- inserts %>%

Readme.Rmd

 
 ![Example `view_regex(text, pattern)`.](docs/view-regex.png)
 
+```r
+t_nested <- "anestedgroupwithingroupexample"
+r_nested <- "(a(nested)(group(within(group))(example)))"
+view_regex(t_nested, r_nested)
+```
+
+![Example of nested groups](docs/view-nested.png)
+
 
 ## Planned (ish)
 

Readme.md

 
 ![Example `view_regex(text, pattern)`.](docs/view-regex.png)
 
+``` r
+t_nested <- "anestedgroupwithingroupexample"
+r_nested <- "(a(nested)(group(within(group))(example)))"
+view_regex(t_nested, r_nested)
+```
+
+![Example of nested groups](docs/view-nested.png)
+
 ## Planned (ish)
 
 1.  An Rstudio addin gadget that allows you to interactively enter the