WIPakislyuk-jmespath-support

4 files changed, 21 insertions, 8 deletions

diff --git a/README.rst b/README.rst
index 4af39be..56ebfb8 100644
--- a/README.rst
+++ b/README.rst
@@ -1,5 +1,5 @@
-yq: Command-line YAML processor - jq wrapper for YAML documents
-===============================================================
+yq: Command-line YAML processor - jq and JMESPath wrapper for YAML documents
+============================================================================
 
 Installation
 ------------
@@ -26,6 +26,12 @@ JSON output back into fancier-than-JSON YAML; the transformation is one-way only
 unless there was an error in YAML parsing, in which case the exit code is 1. See the `jq manual
 <https://stedolan.github.io/jq/manual/>`_ for more details on jq features and options.
 
+JMESPath mode
+-------------
+
+In addition to the default, jq wrapper mode, yq supports `JMESPath <http://jmespath.org/>`_ expressions via the
+``--jmespath PATH`` option.
+
 .. admonition:: Compatibility note
 
  This package's release series available on PyPI begins with version 2.0.0. Versions of ``yq`` prior to 2.0.0 are
diff --git a/scripts/yq b/scripts/yq
index b6672ba..81e501b 100755
--- a/scripts/yq
+++ b/scripts/yq
@@ -2,4 +2,4 @@
 
 from yq import main
 
-main()
+exit(main())
diff --git a/setup.py b/setup.py
index 0406159..85d315d 100755
--- a/setup.py
+++ b/setup.py
@@ -16,7 +16,8 @@ setup(
     long_description=open("README.rst").read(),
     install_requires=[
         "setuptools",
-        "PyYAML >= 3.11"
+        "PyYAML >= 3.11",
+        "jmespath >= 0.9.0"
     ],
     tests_require=tests_require,
     extras_require={"test": tests_require},
diff --git a/yq/__init__.py b/yq/__init__.py
index 6c033cf..6657699 100755
--- a/yq/__init__.py
+++ b/yq/__init__.py
@@ -1,7 +1,7 @@
 """
 yq: Command-line YAML processor - jq wrapper for YAML documents
 
-yq transcodes YAML documents to JSON and passes them to jq.
+yq transcodes YAML documents to JSON and passes them to jq or JMESPath.
 See https://github.com/kislyuk/yq for more information.
 """
 
@@ -13,19 +13,25 @@ import yaml
 class Parser(argparse.ArgumentParser):
     def print_help(self):
         yq_help = argparse.ArgumentParser.format_help(self).splitlines()
-        print("\n".join(["usage: yq [options] <jq filter> [YAML file...]"] + yq_help[1:] + [""]))
+        print("\n".join(["usage: yq [options] <jq or jmespath filter>"] + yq_help[1:] + [""]))
         try:
             subprocess.check_call(["jq", "--help"])
         except:
             pass
 
 parser = Parser(description=__doc__, formatter_class=argparse.RawTextHelpFormatter)
+parser.add_argument("--jmespath", help="Use jmespath with this expression instead of launching the yq subprocess")
 parser.add_argument("jq_args", nargs=argparse.REMAINDER)
 
 def main(args=None):
     args = parser.parse_args(args=args)
     if sys.stdin.isatty():
-        return parser.print_help()
+        parser.print_help()
+        return os.EX_OK
+    if args.jmespath is not None:
+        import jmespath
+        print(jmespath.search(args.jmespath, yaml.safe_load(sys.stdin)))
+        return os.EX_OK
     try:
         # Note: universal_newlines is just a way to induce subprocess to make stdin a text buffer and encode it for us
         jq = subprocess.Popen(['jq'] + args.jq_args, stdin=subprocess.PIPE, universal_newlines=True)
@@ -35,6 +41,6 @@ def main(args=None):
         json.dump(yaml.safe_load(sys.stdin), jq.stdin)
         jq.stdin.close()
         jq.wait()
-        exit(jq.returncode)
+        return jq.returncode
     except Exception as e:
         parser.exit("yq: Error while running jq: {}: {}.".format(type(e).__name__, e))