Redesigned dataset_compliance w/ standard names validation

cfdm/__init__.py

@@ -210,7 +210,7 @@
 
 from .constants import masked
 
-# Internal ones passed on so they can be used in cf-python (see
+# Note internal ones here are passed on so they can be used in cf-python (see
 # comment below)
 from .functions import (
     ATOL,
@@ -249,6 +249,12 @@
     _display_or_return,
 )
 
+from .cfvalidation import (
+    get_all_current_standard_names,
+    _extract_names_from_xml,
+    _STD_NAME_CURRENT_XML_URL
+)
+
 from .constructs import Constructs
 
 from .data import (

cfdm/cfvalidation.py

@@ -0,0 +1,114 @@
+import logging
+import os
+import pprint
+import re
+
+from functools import lru_cache
+
+# Prefer using built-in urllib to extract XML from cf-convention.github.io repo
+# over the 'github' module to use the GitHub API directly, because it avoids
+# the need for another dependency to the CF Data Tools.
+from urllib import request
+
+# To parse the XML - better than using manual regex parsing!
+import xml.etree.ElementTree as ET
+
+logger = logging.getLogger(__name__)
+
+
+# This is the data at the repo location:
+# 'github.com/cf-convention/cf-convention.github.io/blob/main/Data/'
+# 'cf-standard-names/current/src/cf-standard-name-table.xml' but use this
+# form under 'https://raw.githubusercontent.com/' for raw XML content only.
+# Note: the raw XML is also made available at:
+# 'cfconventions.org/Data/cf-standard-names/current/src/cf-standard-name-'
+# 'table.xml', is that a better location to grab from (may be more stable)?
+_STD_NAME_CURRENT_XML_URL = (
+    "https://raw.githubusercontent.com/"
+    "cf-convention/cf-convention.github.io/refs/heads/main/Data/"
+    "cf-standard-names/current/src/cf-standard-name-table.xml"
+)
+
+
+def _extract_names_from_xml(snames_xml, include_aliases):
+    """Extract standard names from a valid Standard Name Table XML document.
+
+    Whether or not to include registered aliases is dependent on the value
+    of the `include_aliases` flag.
+
+    .. versionadded:: NEXTVERSION
+
+     :Parameters:
+
+         snames_xml: `bytes`
+             Bytes representing an XML file of any
+             valid Standard Name Table XML document, or mocked-up
+             equivalent form. 'entry id' items are extracted, along
+             with 'alias id' items if requested.
+
+         include_aliases: `bool`
+             If `True`, include standard names that are aliases
+             rather than strict entries of the input table. By
+             default this is `False` so that aliases are excluded.
+
+     :Returns:
+
+         `list`
+             A list of all CF Conventions standard names in the
+             given version of the table, including aliases if
+             requested.
+
+    """
+    root = ET.fromstring(snames_xml)
+    # Want all <entry id="..."> elements. Note the regex this corresponds
+    # to, from SLB older code, is 're.compile(r"<entry id=\"(.+)\">")' but
+    # using the ElementTree is a much more robust means to extract
+    all_standard_names = [
+        entry.attrib["id"] for entry in root.findall(".//entry")
+    ]
+    if include_aliases:
+        all_standard_names += [
+            entry.attrib["id"] for entry in root.findall(".//alias")
+        ]
+
+    return all_standard_names
+
+
+@lru_cache
+def get_all_current_standard_names(include_aliases=False):
+    """Get a list of all CF Standard Names from the current version table.
+
+    Entries are always returned from the current table. By default aliases
+    are not included in the output but can also be included by setting the
+    `include_aliases` flag to `True`.
+
+    .. versionadded:: NEXTVERSION
+
+     :Parameters:
+
+         include_aliases: `bool`, optional
+             If `True`, include standard names that are aliases
+             rather than strict entries of the current table. By
+             default this is `False` so that aliases are excluded.
+
+     :Returns:
+
+         `list`
+             A list of all CF Conventions standard names in the
+             current version of the table, including aliases if
+             requested.
+
+    """
+    logger.info(
+        "Retrieving XML for set of current standard names from: ",
+        _STD_NAME_CURRENT_XML_URL
+    )  # pragma: no cover
+    with request.urlopen(_STD_NAME_CURRENT_XML_URL) as response:
+        all_snames_xml = response.read()
+
+    logger.debug(
+        f"Successfully retrieved list of {len(all_snames_xml)} standard names"
+    )  # pragma: no cover
+
+    return _extract_names_from_xml(
+        all_snames_xml, include_aliases=include_aliases)