import/cran: Reduce false positives in extracting imports.

* tests/import/cran.scm: Add tests for extract-imports.
* guix/import/cran.scm (extract-imports): New procedure, extracted from...
(needed-test-inputs-in-directory): ...this procedure, which now uses it.
(import-pattern): Update regex pattern.

Change-Id: I07ac3f685ff08a0fa7da3c25cf1f63fbca18b95f

guix/import/cran.scm

@@ -59,6 +59,7 @@
             %bioconductor-version
             download
             fetch-description
+            extract-imports
 
             cran->guix-package
             bioconductor->guix-package
@@ -573,9 +574,27 @@ referenced in build system files."
     ;; Or perhaps...
     "|"
     ;; ...direct namespace access.
-    " *([A-Za-z0-9]+):::?"
+    " *([A-Za-z0-9._]+):::?"
     ")")))
 
+(define* (extract-imports line
+                          #:key (initial-set (set)) (ignored-names (list)))
+  "Return a set of strings corresponding to R libraries that are directly
+referenced by namespace on LINE."
+  (fold (lambda (match acc)
+          (let ((imported (or (match:substring match 4)
+                              (match:substring match 5))))
+            (if (or (not imported)
+                    ;; Likely inside a string.
+                    (odd? (string-count (match:prefix match) #\"))
+                    ;; Part of a bigger expression.
+                    (string-suffix? ":" (match:prefix match))
+                    (member imported ignored-names))
+                acc
+                (set-insert imported acc))))
+        initial-set
+        (list-matches import-pattern line)))
+
 (define (needed-test-inputs-in-directory dir)
   "Return a set of R package names that are found in library import
 statements in files in the directory DIR."
@@ -598,17 +617,10 @@ statements in files in the directory DIR."
                                  (cond
                                   ((eof-object? line) packages)
                                   (else
-                                   (loop
+                                   (loop (extract-imports line
-                                    (fold (lambda (match acc)
+                                                          #:initial-set packages
-                                            (let ((imported (or (match:substring match 4)
+                                                          #:ignored-names (cons package-directory-name
-                                                                (match:substring match 5))))
+                                                                                default-r-packages))))))))))
-                                              (if (or (not imported)
-                                                      (string=? imported package-directory-name)
-                                                      (member imported default-r-packages))
-                                                  acc
-                                                  (set-insert imported acc))))
-                                          packages
-                                          (list-matches import-pattern line))))))))))
                        (set)
                        (append-map (lambda (directory)
                                      (find-files directory "\\.(R|Rmd)"))

tests/import/cran.scm

@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2015 Ricardo Wurmus <rekado@elephly.net>
+;;; Copyright © 2015, 2025 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -20,6 +20,7 @@
 (define-module (test-cran)
   #:use-module (gnu packages statistics)
   #:use-module (guix import cran)
+  #:use-module (guix sets)
   #:use-module (guix tests)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-64)
@@ -88,7 +89,21 @@ Date/Publication: 2015-07-14 14:15:16
   '()
   ((@@ (guix import cran) listify) simple-alist "BadList"))
 
-(test-equal "r-mininal is not a cran package"
+(test-equal "extract-imports: finds data.table"
+  (list "data.table")
+  (set->list ((@ (guix import cran) extract-imports) "abc + data.table::some_procedure()")))
+
+(test-equal "extract-imports: ignores text inside strings"
+  (list)
+  (set->list ((@ (guix import cran) extract-imports)
+              "\"hello::world\", \"this is not data.table::some_procedure(), actually\"")))
+
+(test-equal "extract-imports: ignores other colon separated things"
+  (list)
+  (set->list ((@ (guix import cran) extract-imports)
+              "this:is:not::a:procedure")))
+
+(test-equal "r-minimal is not a cran package"
   #f
   ((@@ (guix import cran) cran-package?) r-minimal))