command: add spack find --json

This is another machine-readable version of `spack find`.  Supplying the
`--json` argument causes specs to be written out as json records,
easily filered with tools like jq.

e.g.:

    $ spack find --json python | jq -C ".[] | { name, version } "
    [
      {
        "name": "python",
        "version": "2.7.16"
      },
      {
        "name": "bzip2",
        "version": "1.0.8"
      }
    ]

lib/spack/spack/cmd/__init__.py

@@ -21,6 +21,7 @@
 import spack.paths
 import spack.spec
 import spack.store
+import spack.util.spack_json as sjson
 from spack.error import SpackError
 
 
@@ -214,6 +215,24 @@ def display_formatted_specs(specs, format_string, deps=False):
                 print("   " * depth, dep.format(format_string))
 
 
+def display_specs_as_json(specs, deps=False):
+    """Convert specs to a list of json records."""
+    seen = set()
+    records = []
+    for spec in specs:
+        if spec.dag_hash() not in seen:
+            seen.add(spec.dag_hash())
+            records.append(spec.to_record_dict())
+
+        if deps:
+            for dep in spec.traverse():
+                if dep.dag_hash() not in seen:
+                    seen.add(spec.dag_hash())
+                    records.append(dep.to_record_dict())
+
+    sjson.dump(records, sys.stdout)
+
+
 def display_specs(specs, args=None, **kwargs):
     """Display human readable specs with customizable formatting.
 

lib/spack/spack/cmd/find.py

@@ -2,6 +2,7 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
 from __future__ import print_function
 
 import llnl.util.tty as tty
@@ -12,7 +13,6 @@
 import spack.repo
 import spack.cmd as cmd
 import spack.cmd.common.arguments as arguments
-from spack.cmd import display_specs
 from spack.util.string import plural
 
 description = "list and search installed packages"
@@ -36,6 +36,9 @@ def setup_parser(subparser):
     format_group.add_argument(
         "--format", action="store", default=None,
         help="output specs with the specified format string")
+    format_group.add_argument(
+        "--json", action="store_true", default=False,
+        help="output specs as machine-readable json records")
 
     # TODO: separate this entirely from the "mode" option -- it's
     # TODO: orthogonal, but changing it for all commands that use it with
@@ -159,14 +162,14 @@ def display_env(env, args, decorator):
     else:
         tty.msg('Root specs')
         # TODO: Change this to not print extraneous deps and variants
-        display_specs(
+        cmd.display_specs(
             env.user_specs, args,
             decorator=lambda s, f: color.colorize('@*{%s}' % f))
         print()
 
     if args.show_concretized:
         tty.msg('Concretized roots')
-        display_specs(
+        cmd.display_specs(
             env.specs_by_hash.values(), args, decorator=decorator)
         print()
 
@@ -205,4 +208,4 @@ def find(parser, args):
         if env:
             display_env(env, args, decorator)
         tty.msg("%s" % plural(len(results), 'installed package'))
-        display_specs(results, args, decorator=decorator, all_headers=True)
+        cmd.display_specs(results, args, decorator=decorator, all_headers=True)

lib/spack/spack/environment.py

@@ -952,6 +952,7 @@ def _shell_vars(self):
             ('PKG_CONFIG_PATH', ['lib/pkgconfig', 'lib64/pkgconfig']),
             ('CMAKE_PREFIX_PATH', ['']),
         ]
+
         path_updates = list()
         if default_view_name in self.views:
             for var, subdirs in updates:

lib/spack/spack/spec.py

@@ -1540,6 +1540,31 @@ def to_dict(self, hash=ht.dag_hash):
 
         return syaml_dict([('spec', node_list)])
 
+    def to_record_dict(self):
+        """Return a "flat" dictionary with name and hash as top-level keys.
+
+        This is similar to ``to_node_dict()``, but the name and the hash
+        are "flattened" into the dictionary for easiler parsing by tools
+        like ``jq``.  Instead of being keyed by name or hash, the
+        dictionary "name" and "hash" fields, e.g.::
+
+            {
+              "name": "openssl"
+              "hash": "3ws7bsihwbn44ghf6ep4s6h4y2o6eznv"
+              "version": "3.28.0",
+              "arch": {
+              ...
+            }
+
+        But is otherwise the same as ``to_node_dict()``.
+
+        """
+        dictionary = syaml_dict()
+        dictionary["name"] = self.name
+        dictionary["hash"] = self.dag_hash()
+        dictionary.update(self.to_node_dict()[self.name])
+        return dictionary
+
     def to_yaml(self, stream=None, hash=ht.dag_hash):
         return syaml.dump(
             self.to_dict(hash), stream=stream, default_flow_style=False)