ref: 8f1eb1ac77640d9cd189c49fe48af8cde65eceb1
dir: /sys/src/cmd/python/Tools/bgen/bgen/bgenStringBuffer.py/
"""Buffers used to hold null-terminated strings."""
from bgenBuffer import FixedOutputBufferType
from bgenStackBuffer import StackOutputBufferType
from bgenHeapBuffer import HeapOutputBufferType
class StringBufferMixIn:
"""Mix-in class to create various string buffer types.
Strings are character arrays terminated by a null byte.
(For input, this is also covered by stringptr.)
For output, there are again three variants:
- Fixed: size is a constant given in the documentation; or
- Stack: size is passed to the C function but we decide on a size at
code generation time so we can still allocate on the heap); or
- Heap: size is passed to the C function and we let the Python caller
pass a size.
(Note that this doesn't cover output parameters in which a string
pointer is returned. These are actually easier (no allocation) but far
less common. I'll write the classes when there is demand.)
"""
def getSizeDeclarations(self, name):
return []
def getAuxDeclarations(self, name):
return []
def getargsFormat(self):
return "s"
def getargsArgs(self, name):
return "&%s__in__" % name
def mkvalueFormat(self):
return "s"
def mkvalueArgs(self, name):
return "%s__out__" % name
class FixedOutputStringType(StringBufferMixIn, FixedOutputBufferType):
"""Null-terminated output string -- passed without size.
Instantiate with buffer size as parameter.
"""
class StackOutputStringType(StringBufferMixIn, StackOutputBufferType):
"""Null-terminated output string -- passed as (buffer, size).
Instantiate with buffer size as parameter.
"""
class HeapOutputStringType(StringBufferMixIn, HeapOutputBufferType):
"""Null-terminated output string -- passed as (buffer, size).
Instantiate without parameters.
Call from Python with buffer size.
"""