Implement a yaml formatter in cliff

This change replaces the cliff-tablib yaml formatter with an internal
replacement. It differs from the tablib formatter in the following ways:
- always outputs with block formatting rather than the PyYAML default
  of deciding based on value content
- emit_one serialises a simple dict where the column name is the key
  and the data item is the value (rather than a list of dicts with
  'Field' and 'Value' keys)
- emit_one preserves column order by printing a single-item dict for
  each column_name

The cliff release which contains this change will need a corresponding
cliff-tablib release which removes the yaml formatter from its setup.py
entry_points.

Change-Id: I691dbab3dee7c5ec28b1083f87ab1f5c051d582b
Related-Bug: #1308744

cliff/formatters/yaml_format.py

@@ -0,0 +1,23 @@
+"""Output formatters using PyYAML.
+"""
+
+import yaml
+
+from .base import ListFormatter, SingleFormatter
+
+
+class YAMLFormatter(ListFormatter, SingleFormatter):
+
+    def add_argument_group(self, parser):
+        pass
+
+    def emit_list(self, column_names, data, stdout, parsed_args):
+        items = []
+        for item in data:
+            items.append(dict(zip(column_names, item)))
+        yaml.safe_dump(items, stream=stdout, default_flow_style=False)
+
+    def emit_one(self, column_names, data, stdout, parsed_args):
+        for key, value in zip(column_names, data):
+            dict_data = {key: value}
+            yaml.safe_dump(dict_data, stream=stdout, default_flow_style=False)

cliff/tests/test_formatters_yaml.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+from six import StringIO
+import yaml
+
+from cliff.formatters import yaml_format
+
+import mock
+
+
+def test_yaml_format_one():
+    sf = yaml_format.YAMLFormatter()
+    c = ('a', 'b', 'c', 'd')
+    d = ('A', 'B', 'C', '"escape me"')
+    expected = {
+        'a': 'A',
+        'b': 'B',
+        'c': 'C',
+        'd': '"escape me"'
+    }
+    output = StringIO()
+    args = mock.Mock()
+    sf.emit_one(c, d, output, args)
+    actual = yaml.safe_load(output.getvalue())
+    assert expected == actual
+
+
+def test_yaml_format_list():
+    sf = yaml_format.YAMLFormatter()
+    c = ('a', 'b', 'c')
+    d = (
+        ('A1', 'B1', 'C1'),
+        ('A2', 'B2', 'C2'),
+        ('A3', 'B3', 'C3')
+    )
+    expected = [
+        {'a': 'A1', 'b': 'B1', 'c': 'C1'},
+        {'a': 'A2', 'b': 'B2', 'c': 'C2'},
+        {'a': 'A3', 'b': 'B3', 'c': 'C3'}
+    ]
+    output = StringIO()
+    args = mock.Mock()
+    sf.add_argument_group(args)
+    sf.emit_list(c, d, output, args)
+    actual = yaml.safe_load(output.getvalue())
+    assert expected == actual

doc/source/list_commands.rst

@@ -90,10 +90,34 @@ a script.
     Makefile is 5569 bytes
     source is 408 bytes
 
+yaml
+----
+
+The ``yaml`` formatter uses PyYAML_ to produce a YAML sequence of
+mappings.
+
+.. _PyYAML: http://pyyaml.org/
+
+::
+
+    (.venv)$ cliffdemo files -f yaml
+    - Name: dist
+      Size: 4096
+    - Name: cliffdemo.egg-info
+      Size: 4096
+    - Name: README.rst
+      Size: 960
+    - Name: setup.py
+      Size: 1807
+    - Name: build
+      Size: 4096
+    - Name: cliffdemo
+      Size: 4096
+
 Other Formatters
 ----------------
 
-Formatters using tablib_ to produce JSON, YAML, and HTML are available
+Formatters using tablib_ to produce JSON and HTML are available
 as part of `cliff-tablib`_.
 
 .. _cliff-tablib: https://github.com/dreamhost/cliff-tablib

doc/source/show_commands.rst

@@ -83,10 +83,27 @@ value of the field or fields.
     (.venv)$ echo $SIZE
     5916
 
+yaml
+----
+
+The ``yaml`` formatter uses PyYAML_ to produce a YAML mapping where
+the field name is the key.
+
+.. _PyYAML: http://pyyaml.org/
+
+::
+
+    (.venv)$ cliffdemo file -f yaml setup.py
+    Name: setup.py
+    Size: 1807
+    UID: 1000
+    GID: 1000
+    Modified Time: 1393531476.9587486
+
 Other Formatters
 ----------------
 
-Formatters using tablib_ to produce JSON, YAML, and HTML are available
+Formatters using tablib_ to produce JSON and HTML are available
 as part of `cliff-tablib`_.
 
 .. _cliff-tablib: https://github.com/dreamhost/cliff-tablib

requirements.txt

@@ -9,3 +9,4 @@ pyparsing>=2.0.1
 six>=1.9.0
 stevedore>=1.5.0 # Apache-2.0
 unicodecsv>=0.8.0
+PyYAML>=3.1.0

setup.cfg

@@ -30,11 +30,13 @@ cliff.formatter.list =
     table = cliff.formatters.table:TableFormatter
     csv = cliff.formatters.commaseparated:CSVLister
     value = cliff.formatters.value:ValueFormatter
+    yaml = cliff.formatters.yaml_format:YAMLFormatter
 
 cliff.formatter.show =
     table = cliff.formatters.table:TableFormatter
     shell = cliff.formatters.shell:ShellFormatter
     value = cliff.formatters.value:ValueFormatter
+    yaml = cliff.formatters.yaml_format:YAMLFormatter
 
 cliff.formatter.completion =
     bash = cliff.complete:CompleteBash