default to non-braced single item mappings in flow sequences0.15.64

11 files changed, 88 insertions, 32 deletions

diff --git a/CHANGES b/CHANGES
index 288eeb8..ca5b22e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,11 @@
+[0, 15, 64]: 2018-08-30
+  - support round-trip of tagged sequences: ``!Arg [a, {b: 1}]``
+  - single entry mappings in flow sequences now written by default without quotes
+    set ``yaml.brace_single_entry_mapping_in_flow_sequence=True`` to force
+    getting ``[a, {b: 1}, {c: {d: 2}}]`` instead of the default ``[a, b: 1, c: {d: 2}]``
+  - fix issue when roundtripping floats starting with a dot such as ``.5``
+    (reported by `Harrison Gregg <https://bitbucket.org/HarrisonGregg/>`__)
+
 [0, 15, 63]: 2018-08-29
   - small fix only necessary for Windows users that don't use wheels.
 
diff --git a/README.rst b/README.rst
index d20ffe1..cae9f2b 100644
--- a/README.rst
+++ b/README.rst
@@ -4,8 +4,8 @@ ruamel.yaml
 
 ``ruamel.yaml`` is a YAML 1.2 loader/dumper package for Python.
 
-:version:       0.15.63
-:updated:       2018-08-29
+:version:       0.15.64
+:updated:       2018-08-30
 :documentation: http://yaml.readthedocs.io
 :repository:    https://bitbucket.org/ruamel/
 :pypi:          https://pypi.org/project/ruamel.yaml/
@@ -54,8 +54,13 @@ ChangeLog
 
 .. should insert NEXT: at the beginning of line for next key (with empty line)
 
-NEXT:
+0.15.64 (2018-08-30):
   - support round-trip of tagged sequences: ``!Arg [a, {b: 1}]``
+  - single entry mappings in flow sequences now written by default without quotes
+    set ``yaml.brace_single_entry_mapping_in_flow_sequence=True`` to force
+    getting ``[a, {b: 1}, {c: {d: 2}}]`` instead of the default ``[a, b: 1, c: {d: 2}]``
+  - fix issue when roundtripping floats starting with a dot such as ``.5``
+    (reported by `Harrison Gregg <https://bitbucket.org/HarrisonGregg/>`__)
 
 0.15.63 (2018-08-29):
   - small fix only necessary for Windows users that don't use wheels.
diff --git a/__init__.py b/__init__.py
index 71d15b2..1638ae5 100644
--- a/__init__.py
+++ b/__init__.py
@@ -7,8 +7,8 @@ if False:  # MYPY
 
 _package_data = dict(
     full_package_name='ruamel.yaml',
-    version_info=(0, 15, 63),
-    __version__='0.15.63',
+    version_info=(0, 15, 64),
+    __version__='0.15.64',
     author='Anthon van der Neut',
     author_email='a.van.der.neut@ruamel.eu',
     description='ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order',  # NOQA
diff --git a/_doc/_static/pypi.svg b/_doc/_static/pypi.svg
index 8e6d98c..04d56a6 100644
--- a/_doc/_static/pypi.svg
+++ b/_doc/_static/pypi.svg
@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="86" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="a"><rect width="86" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#a)"><path fill="#555" d="M0 0h33v20H0z"/><path fill="#007ec6" d="M33 0h53v20H33z"/><path fill="url(#b)" d="M0 0h86v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="110"> <text x="175" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="230">pypi</text><text x="175" y="140" transform="scale(.1)" textLength="230">pypi</text><text x="585" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="430">0.15.63</text><text x="585" y="140" transform="scale(.1)" textLength="430">0.15.63</text></g> </svg>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="86" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="a"><rect width="86" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#a)"><path fill="#555" d="M0 0h33v20H0z"/><path fill="#007ec6" d="M33 0h53v20H33z"/><path fill="url(#b)" d="M0 0h86v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="110"> <text x="175" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="230">pypi</text><text x="175" y="140" transform="scale(.1)" textLength="230">pypi</text><text x="585" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="430">0.15.64</text><text x="585" y="140" transform="scale(.1)" textLength="430">0.15.64</text></g> </svg>
diff --git a/_test/test_spec_examples.py b/_test/test_spec_examples.py
index ba38585..c95b5aa 100644
--- a/_test/test_spec_examples.py
+++ b/_test/test_spec_examples.py
@@ -1,3 +1,4 @@
+
 from roundtrip import YAML
 import pytest  # NOQA
 
diff --git a/_test/test_tag.py b/_test/test_tag.py
index 47d4722..31a192e 100644
--- a/_test/test_tag.py
+++ b/_test/test_tag.py
@@ -2,7 +2,7 @@
 
 import pytest  # NOQA
 
-from roundtrip import round_trip, round_trip_load
+from roundtrip import round_trip, round_trip_load, YAML
 
 
 def register_xxx(**kw):
@@ -121,13 +121,23 @@ class TestImplicitTaggedNodes:
         round_trip("""\
         - !Scalar abcdefg
         """)
-        
+
     def test_mapping(self):
         round_trip("""\
         - !Mapping {a: 1, b: 2}
         """)
 
     def test_sequence(self):
-        x = round_trip("""\
+        yaml = YAML()
+        yaml.brace_single_entry_mapping_in_flow_sequence = True
+        yaml.mapping_value_align = True
+        yaml.round_trip("""
         - !Sequence [a, {b: 1}, {c: {d: 3}}]
         """)
+
+    def test_sequence2(self):
+        yaml = YAML()
+        yaml.mapping_value_align = True
+        yaml.round_trip("""
+        - !Sequence [a, b: 1, c: {d: 3}]
+        """)
diff --git a/constructor.py b/constructor.py
index 26a4dd1..169155c 100644
--- a/constructor.py
+++ b/constructor.py
@@ -1562,15 +1562,15 @@ class RoundTripConstructor(SafeConstructor):
                 yield data2
                 return
             elif isinstance(node, SequenceNode):
-                data = CommentedSeq()
-                data._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+                data3 = CommentedSeq()
+                data3._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
                 if node.flow_style is True:
-                    data.fa.set_flow_style()
+                    data3.fa.set_flow_style()
                 elif node.flow_style is False:
-                    data.fa.set_block_style()
-                data.yaml_set_tag(node.tag)
-                yield data
-                data.extend(self.construct_sequence(node))
+                    data3.fa.set_block_style()
+                data3.yaml_set_tag(node.tag)
+                yield data3
+                data3.extend(self.construct_sequence(node))
                 return
         except:  # NOQA
             pass
diff --git a/emitter.py b/emitter.py
index 5e5e29a..f48899b 100644
--- a/emitter.py
+++ b/emitter.py
@@ -111,9 +111,10 @@ class Emitter(object):
         block_seq_indent=None,
         top_level_colon_align=None,
         prefix_colon=None,
+        brace_single_entry_mapping_in_flow_sequence=None,
         dumper=None,
     ):
-        # type: (StreamType, Any, Optional[int], Optional[int], Optional[bool], Any, Optional[int], Optional[bool], Any, Any) -> None  # NOQA
+        # type: (StreamType, Any, Optional[int], Optional[int], Optional[bool], Any, Optional[int], Optional[bool], Any, Optional[bool], Any) -> None  # NOQA
         self.dumper = dumper
         if self.dumper is not None and getattr(self.dumper, '_emitter', None) is None:
             self.dumper._emitter = self
@@ -136,8 +137,9 @@ class Emitter(object):
         self.indents = Indents()
         self.indent = None  # type: Optional[int]
 
-        # Flow level.
-        self.flow_level = 0
+        # flow_context is an expanding/shrinking list consisting of '{' and '['
+        # for each unclosed flow context. If empty list that means block context
+        self.flow_context = []  # type: List[Text]
 
         # Contexts.
         self.root_context = False
@@ -162,6 +164,10 @@ class Emitter(object):
         # colon handling
         self.colon = u':'
         self.prefixed_colon = self.colon if prefix_colon is None else prefix_colon + self.colon
+        # single entry mappings in flow sequence
+        self.brace_single_entry_mapping_in_flow_sequence = (
+            brace_single_entry_mapping_in_flow_sequence
+        )  # NOQA
 
         # Formatting details.
         self.canonical = canonical
@@ -222,6 +228,11 @@ class Emitter(object):
         except AttributeError:
             return self  # cyaml
 
+    @property
+    def flow_level(self):
+        # type: () -> int
+        return len(self.flow_context)
+
     def dispose(self):
         # type: () -> None
         # Reset the state attributes (to clear self-references)
@@ -421,7 +432,7 @@ class Emitter(object):
                     or self.event.flow_style
                     or self.check_empty_mapping()
                 ):
-                    self.expect_flow_mapping()
+                    self.expect_flow_mapping(single=self.event.nr_items == 1)
                 else:
                     self.expect_block_mapping()
         else:
@@ -448,14 +459,15 @@ class Emitter(object):
         ind = self.indents.seq_flow_align(self.best_sequence_indent, self.column)
         self.write_indicator(u' ' * ind + u'[', True, whitespace=True)
         self.increase_indent(flow=True, sequence=True)
-        self.flow_level += 1
+        self.flow_context.append('[')
         self.state = self.expect_first_flow_sequence_item
 
     def expect_first_flow_sequence_item(self):
         # type: () -> None
         if isinstance(self.event, SequenceEndEvent):
             self.indent = self.indents.pop()
-            self.flow_level -= 1
+            popped = self.flow_context.pop()
+            assert popped == '['
             self.write_indicator(u']', False)
             if self.event.comment and self.event.comment[0]:
                 # eol comment on empty flow sequence
@@ -473,7 +485,8 @@ class Emitter(object):
         # type: () -> None
         if isinstance(self.event, SequenceEndEvent):
             self.indent = self.indents.pop()
-            self.flow_level -= 1
+            popped = self.flow_context.pop()
+            assert popped == '['
             if self.canonical:
                 self.write_indicator(u',', False)
                 self.write_indent()
@@ -493,11 +506,21 @@ class Emitter(object):
 
     # Flow mapping handlers.
 
-    def expect_flow_mapping(self):
-        # type: () -> None
+    def expect_flow_mapping(self, single=False):
+        # type: (Optional[bool]) -> None
         ind = self.indents.seq_flow_align(self.best_sequence_indent, self.column)
-        self.write_indicator(u' ' * ind + u'{', True, whitespace=True)
-        self.flow_level += 1
+        map_init = u'{'
+        if (
+            single
+            and self.flow_level
+            and self.flow_context[-1] == '['
+            and not self.canonical
+            and not self.brace_single_entry_mapping_in_flow_sequence
+        ):
+            # single map item with flow context no curly braces necessary
+            map_init = u''
+        self.write_indicator(u' ' * ind + map_init, True, whitespace=True)
+        self.flow_context.append(map_init)
         self.increase_indent(flow=True, sequence=False)
         self.state = self.expect_first_flow_mapping_key
 
@@ -505,7 +528,8 @@ class Emitter(object):
         # type: () -> None
         if isinstance(self.event, MappingEndEvent):
             self.indent = self.indents.pop()
-            self.flow_level -= 1
+            popped = self.flow_context.pop()
+            assert popped == '{'  # empty flow mapping
             self.write_indicator(u'}', False)
             if self.event.comment and self.event.comment[0]:
                 # eol comment on empty mapping
@@ -528,11 +552,13 @@ class Emitter(object):
             # if self.event.comment and self.event.comment[1]:
             #     self.write_pre_comment(self.event)
             self.indent = self.indents.pop()
-            self.flow_level -= 1
+            popped = self.flow_context.pop()
+            assert popped in [u'{', u'']
             if self.canonical:
                 self.write_indicator(u',', False)
                 self.write_indent()
-            self.write_indicator(u'}', False)
+            if popped != u'':
+                self.write_indicator(u'}', False)
             if self.event.comment and self.event.comment[0]:
                 # eol comment on flow mapping, never reached on empty mappings
                 self.write_post_comment(self.event)
diff --git a/events.py b/events.py
index 672042d..58b2121 100644
--- a/events.py
+++ b/events.py
@@ -46,7 +46,7 @@ class NodeEvent(Event):
 
 
 class CollectionStartEvent(NodeEvent):
-    __slots__ = 'tag', 'implicit', 'flow_style'
+    __slots__ = 'tag', 'implicit', 'flow_style', 'nr_items'
 
     def __init__(
         self,
@@ -57,12 +57,14 @@ class CollectionStartEvent(NodeEvent):
         end_mark=None,
         flow_style=None,
         comment=None,
+        nr_items=None,
     ):
-        # type: (Any, Any, Any, Any, Any, Any, Any) -> None
+        # type: (Any, Any, Any, Any, Any, Any, Any, Optional[int]) -> None
         NodeEvent.__init__(self, anchor, start_mark, end_mark, comment)
         self.tag = tag
         self.implicit = implicit
         self.flow_style = flow_style
+        self.nr_items = nr_items
 
 
 class CollectionEndEvent(Event):
diff --git a/main.py b/main.py
index 653ee1c..2c5c7d5 100644
--- a/main.py
+++ b/main.py
@@ -158,6 +158,8 @@ class YAML(object):
         self.tags = None
         self.default_style = None
         self.top_level_block_style_scalar_no_indent_error_1_1 = False
+        # [a, b: 1, c: {d: 2}]  vs. [a, {b: 1}, {c: {d: 2}}]
+        self.brace_single_entry_mapping_in_flow_sequence = False
 
     @property
     def reader(self):
@@ -239,6 +241,7 @@ class YAML(object):
                     allow_unicode=self.allow_unicode,
                     line_break=self.line_break,
                     prefix_colon=self.prefix_colon,
+                    brace_single_entry_mapping_in_flow_sequence=self.brace_single_entry_mapping_in_flow_sequence,  # NOQA
                     dumper=self,
                 )
                 setattr(self, attr, _emitter)
diff --git a/serializer.py b/serializer.py
index fa4ae62..16763ac 100644
--- a/serializer.py
+++ b/serializer.py
@@ -225,6 +225,7 @@ class Serializer(object):
                         implicit,
                         flow_style=node.flow_style,
                         comment=node.comment,
+                        nr_items=len(node.value),
                     )
                 )
                 for key, value in node.value: