feat: added PURL generation for r parser

cve_bin_tool/parsers/r.py

@@ -2,15 +2,58 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 import json
+import re
 
 from cve_bin_tool.parsers import Parser
 
 
 class RParser(Parser):
+    """
+    Parser implementation for R module files (renv.lock).
+
+    This parser is designed to parse Go module files and generate Package URL (PURL) strings
+    based on the modules and their dependencies listed in the file.
+
+    Attributes:
+        cve_db (CVEDB): The CVE database instance used for vulnerability information.
+        logger (Logger): The logger instance for logging messages and debugging information.
+
+    Methods:
+        generate_purl(product, version, vendor):
+            Generates PURL after normalizing all components.
+        run_checker(filename):
+            Parse the R module file and yield valid PURLs for the modules listed in the file.
+
+    """
+
     def __init__(self, cve_db, logger):
         super().__init__(cve_db, logger)
+        self.purl_pkg_type = "cran"
+
+    def generate_purl(self, product, version, vendor, qualifier={}, subpath=None):
+        """Generates PURL after normalizing all components."""
+
+        product = re.sub(r"[^a-zA-Z0-9.-]", "", product)
+        version = re.sub(r"^[^a-zA-Z0-9]|[^a-zA-Z0-9.-]", "", version)
+        vendor = "UNKNOWN"
+
+        if not re.match(r"^[a-zA-Z0-9_-]", product):
+            return
+        if version == "":
+            version = "UNKNOWN"
+
+        purl = super().generate_purl(
+            product,
+            version,
+            vendor,
+            qualifier,
+            subpath,
+        )
+
+        return purl
 
     def run_checker(self, filename):
+        """Parse the file and yield valid PURLs."""
         self.filename = filename
         with open(self.filename) as fh:
             # parse the json structure for extracting product version pairs