feat: 'parse_known_args()' support

closes #34

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: argparse
 Type: Package
 Title: Command Line Optional and Positional Argument Parser
-Version: 2.0.4
+Version: 2.1.0
 Authors@R: c(person("Trevor L", "Davis", role=c("aut", "cre"), email="[email protected]"),
     person("Allen", "Day", role="ctb", comment="Some documentation and examples ported from the getopt package."),
     person("Python Software Foundation", role="ctb", comment="Some documentation from the optparse Python module."),

NEWS.md

@@ -1,3 +1,9 @@
+argparse 2.1.0
+==============
+
+* Parsers now support ``parse_known_args()`` (#34).
+  Suggestion of David Lacalle Castillo (@WaterKnight1998).
+
 argparse 2.0.4
 ==============
 
@@ -69,12 +75,15 @@ argparse 1.0.4
 * You can now pass in a character vector to the ``metavar`` argument of ``add_argument``.
   Thanks Paul Newell for bug report and a patch.
 * `add_argument` now throws a warning recommending using action "store_true" or "store_false" 
-  if type set to "logical" and action set to "store".  Suggestion of Martí Duran Ferrer
+  if type set to "logical" and action set to "store".  
+  Suggestion of Martí Duran Ferrer
 * You can now explicitly set a `NULL` default in `add_argument`.  
   Previously one could only implicitly set a `NULL` default by not setting any default at all.
   Suggestion of Hyunsoo Kim.
-* Fixes parsing bug when using a very large argument list.  Thanks Taylor Pospisil for bug report.
-* Parse error usage message now prints to standard error.  User requested help message quit status is now zero.  
+* Fixes parsing bug when using a very large argument list.  
+  Thanks Taylor Pospisil for bug report.
+* Parse error usage message now prints to standard error.  
+  User requested help message quit status is now zero.  
   Thanks to PlasmaBinturong for report/request.
 * If Python script fails with error pass on error message to user.
   Thanks to Martí Duran Ferrer for report/request.
@@ -95,7 +104,6 @@ argparse 1.0.0
   but will instead throw an error.  ``argparse`` will continue to ``quit(status=1)`` after printing a help message
   for non-interactive Rscripts.
 
-
 argparse 0.5.3
 ==============
 

R/argparse.R

@@ -39,8 +39,6 @@
 #'
 #' @references Python's \code{argparse} library, which this package is based on,
 #'  is described here: \url{https://docs.python.org/3/library/argparse.html}
-#' @section Acknowledgement:
-#'     A big thanks to Martin Diehl for a bug report.
 #'
 #' @import jsonlite
 #' @import R6
@@ -134,32 +132,14 @@ Parser <- R6Class("Parser", # nolint
                             paste(sprintf("'%s'", args), collapse = ", ")),
                     "print(json.dumps(args.__dict__, sort_keys=True))")
             output <- private$python_code$run(new_code)
-            if (grepl("^usage:", output[1])) {
-                has_positional_arguments <- any(grepl("^positional arguments:", output))
-                has_optional_arguments <- any(grepl("^optional arguments:", output))
-                if (has_positional_arguments || has_optional_arguments) {
-                    .print_message_and_exit(output, "help requested:")
-                } else {
-                    .stop(output, "parse error:")
-                }
-            } else if (grepl("^Traceback", output[1])) {
-                .stop(output, "Error: python error")
-            } else if (any(grepl("^SyntaxError: Non-ASCII character", output))) {
-                message <- paste("Non-ASCII character detected.",
-                               "If you wish to use Unicode arguments/options",
-                               "please upgrade to Python 3.2+",
-                               "Please see file INSTALL for more details.")
-                .stop(message, "non-ascii character error:")
-            } else if (any(grepl("^SyntaxError: positional argument follows keyword argument", output)) ||
-                       grepl("^SyntaxError: non-keyword arg after keyword arg", output[2])) {
-                message <- "Positional argument following keyword argument."
-                .stop(message, "syntax error:")
-            } else if (grepl("^\\{", output)) {
-                args <- jsonlite::fromJSON(paste(output, collapse = ""))
-                return(args)
-            } else { # presumably version number request
-                .print_message_and_exit(output, "version requested:")
-            }
+            parse_args_output(output)
+        },
+        parse_known_args = function(args = commandArgs(TRUE)) {
+            new_code <- c(sprintf("args_remainder = %s.parse_known_args([%s])", private$name,
+                            paste(sprintf("'%s'", args), collapse = ", ")),
+                    "print(json.dumps((args_remainder[0].__dict__, args_remainder[1])))")
+            output <- private$python_code$run(new_code)
+            parse_args_output(output)
         },
         print_help = function() {
             cat(private$python_code$run(sprintf("%s.print_help()", private$name)), sep = "\n")
@@ -207,6 +187,34 @@ Parser <- R6Class("Parser", # nolint
                    n_mutually_exclusive_groups = 0, n_groups = 0)
 )
 
+parse_args_output <- function(output) {
+    if (grepl("^usage:", output[1])) {
+        has_positional_arguments <- any(grepl("^positional arguments:", output))
+        has_optional_arguments <- any(grepl("^optional arguments:", output))
+        if (has_positional_arguments || has_optional_arguments) {
+            .print_message_and_exit(output, "help requested:")
+        } else {
+            .stop(output, "parse error:")
+        }
+    } else if (grepl("^Traceback", output[1])) {
+        .stop(output, "Error: python error")
+    } else if (any(grepl("^SyntaxError: Non-ASCII character", output))) {
+        message <- paste("Non-ASCII character detected.",
+                       "If you wish to use Unicode arguments/options",
+                       "please upgrade to Python 3.2+",
+                       "Please see file INSTALL for more details.")
+        .stop(message, "non-ascii character error:")
+    } else if (any(grepl("^SyntaxError: positional argument follows keyword argument", output)) ||
+               grepl("^SyntaxError: non-keyword arg after keyword arg", output[2])) {
+        message <- "Positional argument following keyword argument."
+        .stop(message, "syntax error:")
+    } else if (grepl("^\\{|^\\[", output)) {
+        args <- jsonlite::fromJSON(paste(output, collapse = ""))
+        return(args)
+    } else { # presumably version number request
+        .print_message_and_exit(output, "version requested:")
+    }
+}
 
 # @param argument argument to be converted from R to Python
 convert_argument <- function(argument) {

cran-comments.rst

@@ -1,9 +1,5 @@
 ## Notes
 
-* The examples and unit tests are now skipped if an appropriate
-  version of Python is not found as with the 'r-devel-windows-x86_64-gcc10-UCRT'
-  CRAN flavor.
-
 * As in previous uploads while in a non-interactive session (i.e. in an
   Rscript) if ``parse_args()`` observes a help flag it will print a usage
   message and then call ``quit()``.  Additionally if a user specifically adds

tests/testthat/test-argparse.R

@@ -137,6 +137,17 @@ test_that("version flags works as expected", {
     expect_equal(length(el), 0)
 })
 
+context("parse_known_args()")
+test_that("parse_known_args() works as expected", {
+    skip_if_not(detects_python())
+    parser <- ArgumentParser()
+    parser$add_argument("-o", "--output_filename", default = "outfile.txt")
+    a_r <- parser$parse_known_args(c("-o", "foobar.txt", "-n", "4"))
+    expect_equal(a_r[[1]]$output_filename, "foobar.txt")
+    expect_equal(a_r[[2]], c("-n", "4"))
+
+})
+
 context("ArgumentParser")
 test_that("ArgumentParser works as expected", {
     skip_if_not(detects_python())