Create a load() method in BaseConstructor and call from yaml.load()

lib/yaml/__init__.py

@@ -8,7 +8,7 @@
 from .loader import *
 from .dumper import *
 
-from .reader import Reader
+from warnings import warn as w
 
 __version__ = '5.4.1'
 try:
@@ -79,41 +79,29 @@ def load(stream, Loader):
     and produce the corresponding Python object.
     """
 
-    # Loader is a *Loader instance:
-    if isinstance(Loader, Reader):
+    if hasattr(Loader, '_yaml_instance'):
         loader = Loader
-
-    # TODO Loader is a _LoaderConfig instance:
-#     elif isinstance(Loader, _LoaderConfig):
-#         loader = Loader.get('loader_class')(stream)
-
     else:
         loader = Loader(stream)
 
-
-    if loader.stream is None:
-        if stream is None:
-            raise TypeError("load() requires stream=...")
-        from .scanner import Scanner
-        from .parser import Parser
-        from .composer import Composer
-        Reader.__init__(loader, stream)
-        Scanner.__init__(loader)
-        Parser.__init__(loader)
-        Composer.__init__(loader)
-
-    try:
-        return loader.get_single_data()
-    finally:
-        loader.dispose()
-        loader.stream = None
+    return loader.load(stream)
 
 def load_all(stream, Loader):
     """
     Parse all YAML documents in a stream
     and produce corresponding Python objects.
     """
-    loader = Loader(stream)
+    if hasattr(Loader, '_yaml_instance'):
+        loader = Loader
+    else:
+        loader = Loader(stream)
+
+    # XXX Not working yet
+    # return loader.load(stream)
+
+    if hasattr(loader, 'stream') and loader.stream is None:
+        loader._init_loader(stream)
+
     try:
         while loader.check_data():
             yield loader.get_data()

lib/yaml/constructor.py

@@ -11,6 +11,11 @@
 from .error import *
 from .nodes import *
 
+from .reader import Reader
+from .scanner import Scanner
+from .parser import Parser
+from .composer import Composer
+
 import collections.abc, datetime, base64, binascii, re, sys, types
 
 class ConstructorError(MarkedYAMLError):
@@ -22,6 +27,8 @@ class BaseConstructor:
     yaml_multi_constructors = {}
 
     def __init__(self):
+        self._yaml_instance = True
+
         self._yaml_constructors = {}
         self.add_constructor = self._add_constructor
         self._yaml_multi_constructors = {}
@@ -32,6 +39,35 @@ def __init__(self):
         self.state_generators = []
         self.deep_construct = False
 
+    def load(self, stream):
+        self._init_loader(stream)
+
+        try:
+            return self.get_single_data()
+        finally:
+            self.dispose()
+            self.stream = None
+
+    def load_all(self, stream):
+        assert False, 'XXX Not working yet'
+
+        self._init_loader(stream)
+
+        try:
+            while self.check_data():
+                yield self.get_data()
+        finally:
+            self.dispose()
+
+    def _init_loader(self, stream):
+        if hasattr(self, 'stream') and self.stream is None:
+            if stream is None:
+                raise TypeError("load() requires stream=...")
+            Reader.__init__(self, stream)
+            Scanner.__init__(self)
+            Parser.__init__(self)
+            Composer.__init__(self)
+
     def check_data(self):
         # If there are more documents available?
         return self.check_node()

lib/yaml/loader.py

@@ -54,7 +54,7 @@ def __init__(self, stream=None):
 # to ensure backwards compatibility.
 class UnsafeLoader(Reader, Scanner, Parser, Composer, Constructor, Resolver):
 
-    def __init__(self, stream):
+    def __init__(self, stream=None):
         Reader.__init__(self, stream)
         Scanner.__init__(self)
         Parser.__init__(self)

tests/lib/canonical.py

@@ -354,7 +354,7 @@ def canonical_load(stream):
 
 yaml.canonical_load = canonical_load
 
-def canonical_load_all(stream):
+def canonical_load_all(stream=None):
     return yaml.load_all(stream, Loader=CanonicalLoader)
 
 yaml.canonical_load_all = canonical_load_all