revset: use decorator to register a function as revset predicate
Using decorator can localize changes for adding (or removing) a revset
predicate function in source code.
It is also useful to pick predicates up for specific purpose. For
example, subsequent patch marks predicates as "safe" by decorator.
This patch defines 'parsefuncdecl()' in 'funcregistrar' class, because
this implementation can be uesd by other decorator class for fileset
predicate and template function.
# registrar.py - utilities to register function for specific purpose
#
# Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
from . import (
util,
)
class funcregistrar(object):
"""Base of decorator to register a fuction for specific purpose
The least derived class can be defined by overriding 'table' and
'formatdoc', for example::
symbols = {}
class keyword(funcregistrar):
table = symbols
formatdoc = ":%s: %s"
@keyword('bar')
def barfunc(*args, **kwargs):
'''Explanation of bar keyword ....
'''
pass
In this case:
- 'barfunc' is registered as 'bar' in 'symbols'
- online help uses ":bar: Explanation of bar keyword"
"""
def __init__(self, decl):
"""'decl' is a name or more descriptive string of a function
Specification of 'decl' depends on registration purpose.
"""
self.decl = decl
table = None
def __call__(self, func):
"""Execute actual registration for specified function
"""
name = self.getname()
if func.__doc__ and not util.safehasattr(func, '_origdoc'):
doc = func.__doc__.strip()
func._origdoc = doc
if callable(self.formatdoc):
func.__doc__ = self.formatdoc(doc)
else:
# convenient shortcut for simple format
func.__doc__ = self.formatdoc % (self.decl, doc)
self.table[name] = func
self.extraaction(name, func)
return func
def getname(self):
"""Return the name of the registered function from self.decl
Derived class should override this, if it allows more
descriptive 'decl' string than just a name.
"""
return self.decl
def parsefuncdecl(self):
"""Parse function declaration and return the name of function in it
"""
i = self.decl.find('(')
if i > 0:
return self.decl[:i]
else:
return self.decl
def formatdoc(self, doc):
"""Return formatted document of the registered function for help
'doc' is '__doc__.strip()' of the registered function.
If this is overridden by non-callable object in derived class,
such value is treated as "format string" and used to format
document by 'self.formatdoc % (self.decl, doc)' for convenience.
"""
raise NotImplementedError()
def extraaction(self, name, func):
"""Execute exra action for registered function, if needed
"""
pass