Added basic 'Require()' class that can check whether a requirement is

installed in a particular location or set of locations, and up-to-date.
Smart defaults make most version checks trivial, e.g.:

    Require('Something','1.2','some.thing').is_current()

    Require('Other',None,'other.thing',attribute='someFunc').is_current()

    Require('Existentialism',None,'existenz').is_current()

The first line checks whether the 'some.thing' module defines a
'__version__' constant that compares >='1.2' (using smart version parsing
from 'distutils.version').  The second checks whether 'other.thing' defines
'someFunc'.  (This latter form ('requested_version=None') is used to do
version sniffing on modules that don't define a version attribute.)
The third format just checks for the existence of the named module.


git-svn-id: svn://svn.eby-sarna.com/svnroot/wsgiref@238 571e12c6-e1fa-0310-aee7-ff1267fa46bd

2 files changed, 329 insertions, 1 deletions

diff --git a/setuptools/depends.py b/setuptools/depends.py
new file mode 100644
index 0000000..c3bc333
--- /dev/null
+++ b/setuptools/depends.py
@@ -0,0 +1,246 @@
+from __future__ import generators
+import sys, imp, marshal
+from imp import PKG_DIRECTORY, PY_COMPILED, PY_SOURCE, PY_FROZEN
+from distutils.version import StrictVersion, LooseVersion
+
+__all__ = [
+    'Require', 'find_module', 'get_module_constant', 'extract_constant'
+]
+
+class Require:
+    """A prerequisite to building or installing a distribution"""
+
+    def __init__(self,name,requested_version,module,attribute=None,format=None):
+
+        if format is None and requested_version is not None:
+            format = StrictVersion
+
+        if format is not None:
+            requested_version = format(requested_version)
+            if attribute is None:
+                attribute = '__version__'
+
+        self.name = name
+        self.requested_version = requested_version
+        self.module = module
+        self.attribute = attribute
+        self.format = format
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+    def get_version(self, paths=None, default="unknown"):
+
+        """Get version number of installed module, 'None', or 'default'
+
+        Search 'paths' for module.  If not found, return 'None'.  If found,
+        return the extracted version attribute, or 'default' if no version
+        attribute was specified, or the value cannot be determined without
+        importing the module.  The version is formatted according to the
+        requirement's version format (if any), unless it is 'None' or the
+        supplied 'default'.
+        """
+
+        if self.attribute is None:
+            try:
+                f,p,i = find_module(self.module,paths)
+                if f: f.close()
+                return default
+            except ImportError:
+                return None
+
+        v = get_module_constant(self.module,self.attribute,default,paths)
+
+        if v is not None and v is not default and self.format is not None:
+            return self.format(v)
+
+        return v
+
+    def is_present(self,paths=None):
+        """Return true if dependency is present on 'paths'"""
+        return self.get_version(paths) is not None
+
+    def is_current(self,paths=None):
+        """Return true if dependency is present and up-to-date on 'paths'"""
+        version = self.get_version(paths)
+        if version is None:
+            return False
+        return self.attribute is None or self.format is None or \
+            version >= self.requested_version
+
+
+
+def _iter_code(code):
+
+    """Yield '(op,arg)' pair for each operation in code object 'code'"""
+
+    from array import array
+    from dis import HAVE_ARGUMENT, EXTENDED_ARG
+
+    bytes = array('b',code.co_code)
+    eof = len(code.co_code)
+
+    ptr = 0
+    extended_arg = 0
+
+    while ptr<eof:
+
+        op = bytes[ptr]
+
+        if op>=HAVE_ARGUMENT:
+
+            arg = bytes[ptr+1] + bytes[ptr+2]*256 + extended_arg
+            ptr += 3
+
+            if op==EXTENDED_ARG:
+                extended_arg = arg * 65536L
+                continue
+
+        else:
+            arg = None
+            ptr += 1
+
+        yield op,arg
+
+
+
+
+
+
+
+
+
+
+def find_module(module, paths=None):
+    """Just like 'imp.find_module()', but with package support"""
+
+    parts = module.split('.')
+
+    while parts:
+        part = parts.pop(0)
+        f, path, (suffix,mode,kind) = info = imp.find_module(part, paths)
+
+        if kind==PKG_DIRECTORY:
+            parts = parts or ['__init__']
+            paths = [path]
+
+        elif parts:
+            raise ImportError("Can't find %r in %s" % (parts,module))
+
+    return info
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+def get_module_constant(module, symbol, default=-1, paths=None):
+
+    """Find 'module' by searching 'paths', and extract 'symbol'
+
+    Return 'None' if 'module' does not exist on 'paths', or it does not define
+    'symbol'.  If the module defines 'symbol' as a constant, return the
+    constant.  Otherwise, return 'default'."""
+
+    try:
+        f, path, (suffix,mode,kind) = find_module(module,paths)
+    except ImportError:
+        # Module doesn't exist
+        return None
+
+    try:
+        if kind==PY_COMPILED:
+            f.read(8)   # skip magic & date
+            code = marshal.load(f)
+        elif kind==PY_FROZEN:
+            code = imp.get_frozen_object(module)
+        elif kind==PY_SOURCE:
+            code = compile(f.read(), path, 'exec')
+        else:
+            # Not something we can parse; we'll have to import it.  :(
+            if module not in sys.modules:
+                imp.load_module(module,f,path,(suffix,mode,kind))
+            return getattr(sys.modules[module],symbol,None)
+
+    finally:
+        if f:
+            f.close()
+
+    return extract_constant(code,symbol,default)
+
+
+
+
+
+
+
+
+def extract_constant(code,symbol,default=-1):
+
+    """Extract the constant value of 'symbol' from 'code'
+
+    If the name 'symbol' is bound to a constant value by the Python code
+    object 'code', return that value.  If 'symbol' is bound to an expression,
+    return 'default'.  Otherwise, return 'None'.
+
+    Return value is based on the first assignment to 'symbol'.  'symbol' must
+    be a global, or at least a non-"fast" local in the code block.  That is,
+    only 'STORE_NAME' and 'STORE_GLOBAL' opcodes are checked, and 'symbol'
+    must be present in 'code.co_names'.
+    """
+
+    if symbol not in code.co_names:
+        # name's not there, can't possibly be an assigment
+        return None
+
+    name_idx = list(code.co_names).index(symbol)
+
+    STORE_NAME = 90
+    STORE_GLOBAL = 97
+    LOAD_CONST = 100
+
+    const = default
+
+    for op, arg in _iter_code(code):
+
+        if op==LOAD_CONST:
+            const = code.co_consts[arg]
+        elif arg==name_idx and (op==STORE_NAME or op==STORE_GLOBAL):
+            return const
+        else:
+            const = default
+
+
+
+
+
+
+
diff --git a/setuptools/tests/__init__.py b/setuptools/tests/__init__.py
index 7a5534f..0c4a4f1 100644
--- a/setuptools/tests/__init__.py
+++ b/setuptools/tests/__init__.py
@@ -7,7 +7,11 @@ from distutils.errors import DistutilsSetupError
 import setuptools, setuptools.dist
 from setuptools import Feature
 from distutils.core import Extension
+from setuptools.depends import extract_constant, get_module_constant
+from setuptools.depends import find_module, Require
+from distutils.version import StrictVersion, LooseVersion
 
+import sys, os.path
 
 def makeSetup(**args):
     """Return distribution from 'setup(**args)', without executing commands"""
@@ -35,6 +39,84 @@ def makeSetup(**args):
 
 
 
+class DependsTests(TestCase):
+
+    def testExtractConst(self):
+
+        from setuptools.depends import extract_constant
+
+        def f1():
+            global x,y,z
+            x = "test"
+            y = z
+
+        # unrecognized name
+        self.assertEqual(extract_constant(f1.func_code,'q', -1), None)
+
+        # constant assigned
+        self.assertEqual(extract_constant(f1.func_code,'x', -1), "test")
+
+        # expression assigned
+        self.assertEqual(extract_constant(f1.func_code,'y', -1), -1)
+
+        # recognized name, not assigned
+        self.assertEqual(extract_constant(f1.func_code,'z', -1), None)
+
+
+    def testFindModule(self):
+        self.assertRaises(ImportError, find_module, 'no-such.-thing')
+        self.assertRaises(ImportError, find_module, 'setuptools.non-existent')
+        f,p,i = find_module('setuptools.tests'); f.close()
+
+    def testModuleExtract(self):
+        from distutils import __version__
+        self.assertEqual(
+            get_module_constant('distutils','__version__'), __version__
+        )
+        self.assertEqual(
+            get_module_constant('sys','version'), sys.version
+        )
+        self.assertEqual(
+            get_module_constant('setuptools.tests','__doc__'),__doc__
+        )
+
+    def testRequire(self):
+        req = Require('Distutils','1.0.3','distutils')
+
+        self.assertEqual(req.name, 'Distutils')
+        self.assertEqual(req.module, 'distutils')
+        self.assertEqual(req.requested_version, '1.0.3')
+        self.assertEqual(req.attribute, '__version__')
+
+        from distutils import __version__
+        self.assertEqual(req.get_version(), __version__)
+
+        self.failUnless(req.is_present())
+        self.failUnless(req.is_current())
+
+        req = Require('Distutils 3000','03000','distutils',format=LooseVersion)
+        self.failUnless(req.is_present())
+        self.failIf(req.is_current())
+
+        req = Require('Do-what-I-mean','1.0','d-w-i-m')
+        self.failIf(req.is_present())
+        self.failIf(req.is_current())
+
+        req = Require('Tests', None, 'tests')
+        self.assertEqual(req.format, None)
+        self.assertEqual(req.attribute, None)
+        self.assertEqual(req.requested_version, None)
+
+        paths = [os.path.dirname(p) for p in __path__]
+        self.failUnless(req.is_present(paths))
+        self.failUnless(req.is_current(paths))
+
+
+
+
+
+
+
 
 
 
@@ -285,7 +367,7 @@ class TestCommandTests(TestCase):
 
 
 
-testClasses = (DistroTests, FeatureTests, TestCommandTests)
+testClasses = (DependsTests, DistroTests, FeatureTests, TestCommandTests)
 
 def test_suite():
     return TestSuite([makeSuite(t,'test') for t in testClasses])