spack list: latest version (JSON)

List the latest version of each package in JSON encoding.
Preparation for consumption for a "spack badge" service.

lib/spack/spack/cmd/list.py

@@ -20,6 +20,7 @@
 import spack.dependency
 import spack.repo
 import spack.cmd.common.arguments as arguments
+from spack.version import VersionList
 
 description = "list and search available packages"
 section = "basic"
@@ -116,6 +117,31 @@ def rows_for_ncols(elts, ncols):
         yield row
 
 
+@formatter
+def version_json(pkg_names, out):
+    """Print all packages with their latest versions."""
+    pkgs = [spack.repo.get(name) for name in pkg_names]
+
+    out.write('[\n')
+
+    # output name and latest version for each package
+    pkg_latest = ",\n".join([
+        '  {{"name": "{0}",\n'
+        '   "latest_version": "{1}",\n'
+        '   "homepage": "{2}",\n'
+        '   "file": "{3}"'
+        '}}'.format(
+            pkg.name,
+            VersionList(pkg.versions).highest_numeric(True),
+            pkg.homepage,
+            github_url(pkg)
+        ) for pkg in pkgs
+    ])
+    out.write(pkg_latest)
+    # important: no trailing comma in JSON arrays
+    out.write('\n]\n')
+
+
 @formatter
 def html(pkg_names, out):
     """Print out information on all packages in Sphinx HTML.

lib/spack/spack/test/cmd/list.py

@@ -45,6 +45,14 @@ def test_list_format_name_only():
 
 
 @pytest.mark.maybeslow
+def test_list_format_version_json():
+    output = list('--format', 'version_json')
+    assert '  {"name": "cloverleaf3d",' in output
+    assert '  {"name": "hdf5",' in output
+    import json
+    json.loads(output)
+
+
 def test_list_format_html():
     output = list('--format', 'html')
     assert '<div class="section" id="cloverleaf3d">' in output

lib/spack/spack/test/versions.py

@@ -9,7 +9,7 @@
 """
 import pytest
 
-from spack.version import Version, ver
+from spack.version import Version, VersionList, ver
 
 
 def assert_ver_lt(a, b):
@@ -548,3 +548,15 @@ def test_get_item():
     # Raise TypeError on tuples
     with pytest.raises(TypeError):
         b.__getitem__(1, 2)
+
+
+def test_list_highest():
+    vl = VersionList(['master', '1.2.3', 'develop', '3.4.5', 'foobar'])
+    assert vl.highest() == Version('develop')
+    assert vl.lowest() == Version('foobar')
+    assert vl.highest_numeric() == Version('3.4.5')
+
+    vl2 = VersionList(['master', 'develop'])
+    assert vl2.highest_numeric() is None
+    assert vl2.highest_numeric(True) == Version('develop')
+    assert vl2.lowest() == Version('master')

lib/spack/spack/version.py

@@ -643,6 +643,19 @@ def highest(self):
         else:
             return self[-1].highest()
 
+    def highest_numeric(self, fallback_all=False):
+        """Get the highest numeric version in the list."""
+        numeric_versions = list(filter(
+            lambda v: str(v) not in infinity_versions,
+            self.versions))
+        if not any(numeric_versions):
+            if fallback_all:
+                return self.highest()
+            else:
+                return None
+        else:
+            return numeric_versions[-1].highest()
+
     @coerced
     def overlaps(self, other):
         if not other or not self: