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# XXX there is much grot here.
# some of this comes from trying to present a reasonably intuitive and
# useful interface, which implies a certain amount of DWIMmery.
# things surely still could be more transparent.
class FormException(Exception):
pass
class Instruction(object):
def __init__(self, fields):
self.fields = fields
self.lfields = [k for (k,v) in fields.iteritems()
if isinstance(v, str)]
#if not self.lfields:
# self.assemble() # for error checking only
def assemble(self):
r = 0
for field in self.fields:
r |= field.encode(self.fields[field])
return r
class IBoundDesc(object):
def __init__(self, desc, fieldmap, assembler):
self.fieldmap = fieldmap
self.desc = desc
self.assembler = assembler
def calc_fields(self, args, kw):
fieldsleft = list(self.desc.fields)
fieldvalues = {}
for fname in kw:
kw[fname] = self.fieldmap[fname]
for d in (self.desc.specializations, kw):
for field in d:
fieldsleft.remove(field)
fieldvalues[field] = d[field]
for i in range(min(len(self.desc.defaults), len(fieldsleft) - len(args))):
f, v = self.desc.defaults[i]
fieldvalues[f] = v
fieldsleft.remove(f)
for a in args:
field = fieldsleft.pop(0)
fieldvalues[field] = a
return fieldvalues, fieldsleft
def __call__(self, *args, **kw):
fieldvalues, sparefields = self.calc_fields(args, kw)
if sparefields:
raise FormException('fields %s left'%sparefields)
self.assembler.insts.append(Instruction(fieldvalues))
class IBoundDupDesc(IBoundDesc):
def calc_fields(self, args, kw):
s = super(IBoundDupDesc, self)
fieldvalues, sparefields = s.calc_fields(args, kw)
for k, v in self.desc.dupfields.iteritems():
fieldvalues[k] = fieldvalues[v]
return fieldvalues, sparefields
class IDesc(object):
boundtype = IBoundDesc
def __init__(self, fieldmap, fields, specializations, boundtype=None):
self.fieldmap = fieldmap
self.fields = fields
self.specializations = specializations
self.defaults = ()
if boundtype is not None:
self.boundtype = boundtype
for field in specializations:
if field not in fields:
raise FormException(field)
def __get__(self, ob, cls=None):
if ob is None: return self
return self.boundtype(self, self.fieldmap, ob)
def default(self, **defs):
assert len(defs) == 1
f, v = defs.items()[0]
self.defaults = self.defaults + ((self.fieldmap[f], v),)
return self
def __call__(self, **more_specializatons):
s = self.specializations.copy()
ms = {}
ds = {}
for fname, v in more_specializatons.iteritems():
field = self.fieldmap[fname]
if field not in self.fields:
raise FormException("don't know about '%s' here" % field)
if isinstance(v, str):
ds[field] = self.fieldmap[v]
else:
ms[field] = v
s.update(ms)
if len(s) != len(self.specializations) + len(ms):
raise FormException("respecialization not currently allowed")
if ds:
fields = list(self.fields)
for field in ds:
fields.remove(field)
return IDupDesc(self.fieldmap, tuple(fields), s, ds)
else:
r = IDesc(self.fieldmap, self.fields, s, self.boundtype)
r.defaults = tuple([(f, d) for (f, d) in self.defaults if f not in s])
return r
def match(self, inst):
c = 0
for field in self.fields:
if field in self.specializations:
if field.decode(inst) != self.specializations[field]:
return 0
else:
c += 1
return c
def __repr__(self):
l = []
for field in self.fields:
if field in self.specializations:
l.append('%s=%r'%(field.name, self.specializations[field]))
else:
l.append(field.name)
r = '%s(%s)'%(self.__class__.__name__, ', '.join(l))
if self.boundtype is not self.__class__.boundtype:
r += ' => ' + self.boundtype.__name__
return r
def disassemble(self, name, inst, labels, pc):
kws = []
for field in self.fields:
if field not in self.specializations:
v = field.decode(inst)
for f, d in self.defaults:
if f is field:
if d == v:
break
else:
kws.append('%s=%s'%(field.name, field.r(inst, labels, pc)))
return "%-5s %s"%(name, ', '.join(kws))
class IDupDesc(IDesc):
boundtype = IBoundDupDesc
def __init__(self, fieldmap, fields, specializations, dupfields):
super(IDupDesc, self).__init__(fieldmap, fields, specializations)
self.dupfields = dupfields
def match(self, inst):
for field in self.dupfields:
df = self.dupfields[field]
if field.decode(inst) != df.decode(inst):
return 0
else:
return super(IDupDesc, self).match(inst)
class Form(object):
fieldmap = None
def __init__(self, *fnames):
self.fields = []
bits = {}
overlap = False
for fname in fnames:
if isinstance(fname, str):
field = self.fieldmap[fname]
else:
field = fname
if field.overlap:
overlap = True
for b in range(field.left, field.right+1):
if not overlap and b in bits:
raise FormException("'%s' and '%s' clash at bit '%s'"%(
bits[b], fname, b))
else:
bits[b] = fname
self.fields.append(field)
def __call__(self, **specializations):
s = {}
for fname in specializations:
field = self.fieldmap[fname]
if field not in self.fields:
raise FormException("no nothin bout '%s'"%fname)
s[field] = specializations[fname]
return IDesc(self.fieldmap, self.fields, s)
def __repr__(self):
return '%s(%r)'%(self.__class__.__name__, [f.name for f in self.fields])
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