Regex-ified Lookup Table in R

regexLookup.R

    test <- data.frame(
      url = c(
        'google.com/testing/duck',
        'google.com/testing/dog',
        'google.com/testing/cat',
        'google.com/evaluating/duck', 
        'google.com/evaluating/dog', 
        'google.com/evaluating/cat', 
        'google.com/analyzing/duck',
        'google.com/analyzing/dog',
        'google.com/analyzing/cat',
        'banana'
      ),
      content = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10),
      subdir = NA
    )
    
    # List used for key/value lookup, names can be regex
    lookup <- c(
      "testing" = "Testing is important",
      "Eval.*" = 'eval in R',
      "analy(z|s)ing" = 'R is fun'
    )
    
    # lookup <- c('test', 'hey')
    
    # Defining new lookup function
    regexLookup <- function(data, dict, searchColumn, targetColumn, ignore.case = TRUE){
      # Basic check—need to separate errors/handling
      if(is.null(names(dict)) || is.null(dict[[1]])) {
        stop("Not a valid replacement value; use a key/value store for `dict`.")
      }
      
      # Non-standard eval for the column names; not sure if I should
      # add safetytype/checks for these
      searchColumn <- eval(substitute(searchColumn), data)
      targetColumn <- deparse(substitute(targetColumn))
      
      # Define find-and-replace utility
      findAndReplace <- function (key, val){
        data[grepl(key, searchColumn, ignore.case = ignore.case), targetColumn] <- val
        data <<- data
      }
      
      # Map over the key/value store
      mapply(findAndReplace, names(dict), dict)
      
      # Return result, with non-matching rows preserved
      return(data)
    }
    
    regexLookup(test, lookup, url, subdir, ignore.case = FALSE)