[Distutils] FINAL DRAFT: Dependency specifier PEP

[Robert Collins]

Addressed along with some minor quirks and github feedback.

diff --git a/dependency-specification.rst b/dependency-specification.rst
index a9953ed..8a632ba 100644
--- a/dependency-specification.rst
+++ b/dependency-specification.rst
@@ -18,7 +18,7 @@ Abstract
 This PEP specifies the language used to describe dependencies for packages.
 It draws a border at the edge of describing a single dependency - the
 different sorts of dependencies and when they should be installed is a higher
-level problem. The intent is provide a building block for higher layer
+level problem. The intent is to provide a building block for higher layer
 specifications.

 The job of a dependency is to enable tools like pip [#pip]_ to find the right
@@ -85,7 +85,7 @@ Versions may be specified according to the PEP-440
[#pep440]_ rules. (Note:
 URI is defined in std-66 [#std66]_::

     version_cmp   = wsp* '<' | '<=' | '!=' | '==' | '>=' | '>' | '~=' | '==='
-    version       = wsp* ( letterOrDigit | '-' | '_' | '.' | '*' )+
+    version       = wsp* ( letterOrDigit | '-' | '_' | '.' | '*' | '+' | '!' )+
     version_one   = version_cmp version wsp*
     version_many  = version_one (wsp* ',' version_one)*
     versionspec   = ( '(' version_many ')' ) | version_many
@@ -94,7 +94,7 @@ URI is defined in std-66 [#std66]_::
 Environment markers allow making a specification only take effect in some
 environments::

-    marker_op     = version_cmp | 'in' | 'not' wsp+ 'in'
+    marker_op     = version_cmp | (wsp* 'in') | (wsp* 'not' wsp+ 'in')
     python_str_c  = (wsp | letter | digit | '(' | ')' | '.' | '{' | '}' |
                      '-' | '_' | '*')
     dquote        = '"'
@@ -108,10 +108,14 @@ environments::
                      'implementation_name' | 'implementation_version' |
                      'extra' # ONLY when defined by a containing layer
                      )
-    marker_var    = env_var | python_str
-    marker_expr   = ('(' wsp* marker wsp* ')'
-                     | (marker_var wsp* marker_op wsp* marker_var))
-    marker        = wsp* marker_expr ( wsp* ('and' | 'or') wsp* marker_expr)*
+    marker_var    = wsp* (env_var | python_str)
+    marker_expr   = marker_var marker_op marker_var
+                  | wsp* '(' marker wsp* ')'
+    marker_and    = marker_expr wsp* 'and' marker_expr
+                  | marker_expr
+    marker_or     = marker_and wsp* 'or' marker_and
+                      | marker_and
+    marker        = marker_or
     quoted_marker = ';' wsp* marker

 Optional components of a distribution may be specified using the extras
@@ -304,7 +308,7 @@ The ``implementation_version`` marker variable is
derived from
 Backwards Compatibility
 =======================

-Most of this PEP is already widely deployed and thus offers no compatibiltiy
+Most of this PEP is already widely deployed and thus offers no compatibility
 concerns.

 There are however a few points where the PEP differs from the deployed base.
@@ -355,7 +359,7 @@ The complete parsley grammar::
     version_many  = version_one:v1 (wsp* ',' version_one)*:v2 -> [v1] + v2
     versionspec   = ('(' version_many:v ')' ->v) | version_many
     urlspec       = '@' wsp* <URI_reference>
-    marker_op     = version_cmp | 'in' | 'not' wsp+ 'in'
+    marker_op     = version_cmp | (wsp* 'in') | (wsp* 'not' wsp+ 'in')
     python_str_c  = (wsp | letter | digit | '(' | ')' | '.' | '{' | '}' |
                      '-' | '_' | '*' | '#')
     dquote        = '"'
@@ -369,12 +373,14 @@ The complete parsley grammar::
                      'implementation_name' | 'implementation_version' |
                      'extra' # ONLY when defined by a containing layer
                      ):varname -> lookup(varname)
-    marker_var    = env_var | python_str
-    marker_expr   = (("(" wsp* marker:m wsp* ")" -> m)
-                         | ((marker_var:l wsp* marker_op:o wsp* marker_var:r))
-                         -> (l, o, r))
-    marker        = (wsp* marker_expr:m ( wsp* ("and" | "or"):o wsp*
-                     marker_expr:r -> (o, r))*:ms -> (m, ms))
+    marker_var    = wsp* (env_var | python_str)
+    marker_expr   = marker_var:l marker_op:o marker_var:r -> (o, l, r)
+                  | wsp* '(' marker:m wsp* ')' -> m
+    marker_and    = marker_expr:l wsp* 'and' marker_expr:r -> ('and', l, r)
+                  | marker_expr:m -> m
+    marker_or     = marker_and:l wsp* 'or' marker_and:r -> ('or', l, r)
+                      | marker_and:m -> m
+    marker        = marker_or
     quoted_marker = ';' wsp* marker
     identifier    = <letterOrDigit (
                     letterOrDigit |
@@ -469,8 +475,15 @@ A test program - if the grammar is in a string
``grammar``::
         "name>=3,<2",
         "name [fred,bar] @ http://foo.com ; python_version=='2.7'",
         "name[quux, strange];python_version<'2.7' and platform_version=='2'",
-        "name; os_name=='dud' and (os_name=='odd' or os_name=='fred')",
-        "name; os_name=='dud' and os_name=='odd' or os_name=='fred'",
+        "name; os_name=='a' or os_name=='b'",
+        # Should parse as (a and b) or c
+        "name; os_name=='a' and os_name=='b' or os_name=='c'",
+        # Overriding precedence -> a and (b or c)
+        "name; os_name=='a' and (os_name=='b' or os_name=='c')",
+        # should parse as a or (b and c)
+        "name; os_name=='a' or os_name=='b' and os_name=='c'",
+        # Overriding precedence -> (a or b) and c
+        "name; (os_name=='a' or os_name=='b') and os_name=='c'",
         ]

     def format_full_version(info):
@@ -502,8 +515,8 @@ A test program - if the grammar is in a string ``grammar``::

     compiled = makeGrammar(grammar, {'lookup': bindings.__getitem__})
     for test in tests:
-      parsed = compiled(test).specification()
-      print(parsed)
+        parsed = compiled(test).specification()
+        print("%s -> %s" % (test, parsed))

 References
 ==========

On 17 November 2015 at 16:59, Robert Collins <robertc at robertcollins.net> wrote:
> On 17 November 2015 at 16:37, Nathaniel Smith <njs at pobox.com> wrote:
>
> Blah. Shall address.
>
> -Rob
>
>>
>> --
>> Nathaniel J. Smith -- http://vorpus.org
>
>
>
> --
> Robert Collins <rbtcollins at hp.com>
> Distinguished Technologist
> HP Converged Cloud



-- 
Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud