templater: define interface for objects requiring unwrapvalue()

unwrapvalue() is changed to not return a lazy bytes generator for "wrapped"
types because I want to define the tovalue() interface as such. It's a baby
step to unify unwrapvalue() and _unwrapvalue().

mercurial/templateutil.py

@@ -1,537 +1,554 b''
 # templateutil.py - utility for template evaluation
 #
 # Copyright 2005, 2006 Matt Mackall <[e-mail]>
 #
 # 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
 
 import abc
 import types
 
 from .i18n import _
 from . import (
     error,
     pycompat,
     util,
 )
 from .utils import (
     dateutil,
     stringutil,
 )
 
 class ResourceUnavailable(error.Abort):
     pass
 
 class TemplateNotFound(error.Abort):
     pass
 
 class wrapped(object):
     """Object requiring extra conversion prior to displaying or processing
-    as value"""
+    as value
+
+    Use unwrapvalue(), unwrapastype(), or unwraphybrid() to obtain the inner
+    object.
+    """
 
     __metaclass__ = abc.ABCMeta
 
     @abc.abstractmethod
     def show(self, context, mapping):
         """Return a bytes or (possibly nested) generator of bytes representing
         the underlying object
 
         A pre-configured template may be rendered if the underlying object is
         not printable.
         """
 
+    @abc.abstractmethod
+    def tovalue(self, context, mapping):
+        """Move the inner value object out or create a value representation
+
+        A returned value must be serializable by templaterfilters.json().
+        """
+
 # stub for representing a date type; may be a real date type that can
 # provide a readable string value
 class date(object):
     pass
 
 class hybrid(wrapped):
     """Wrapper for list or dict to support legacy template
 
     This class allows us to handle both:
     - "{files}" (legacy command-line-specific list hack) and
     - "{files % '{file}\n'}" (hgweb-style with inlining and function support)
     and to access raw values:
     - "{ifcontains(file, files, ...)}", "{ifcontains(key, extras, ...)}"
     - "{get(extras, key)}"
     - "{files|json}"
     """
 
     def __init__(self, gen, values, makemap, joinfmt, keytype=None):
         if gen is not None:
             self._gen = gen  # generator or function returning generator
         self._values = values
         self._makemap = makemap
         self.joinfmt = joinfmt
         self.keytype = keytype  # hint for 'x in y' where type(x) is unresolved
 
     def _gen(self):
         """Default generator to stringify this as {join(self, ' ')}"""
         for i, x in enumerate(self._values):
             if i > 0:
                 yield ' '
             yield self.joinfmt(x)
     def itermaps(self):
         makemap = self._makemap
         for x in self._values:
             yield makemap(x)
 
     def show(self, context, mapping):
         # TODO: switch gen to (context, mapping) API?
         gen = self._gen
         if callable(gen):
             return gen()
         return gen
 
+    def tovalue(self, context, mapping):
+        # TODO: return self._values and get rid of proxy methods
+        return self
+
     def __contains__(self, x):
         return x in self._values
     def __getitem__(self, key):
         return self._values[key]
     def __len__(self):
         return len(self._values)
     def __iter__(self):
         return iter(self._values)
     def __getattr__(self, name):
         if name not in (r'get', r'items', r'iteritems', r'iterkeys',
                         r'itervalues', r'keys', r'values'):
             raise AttributeError(name)
         return getattr(self._values, name)
 
 class mappable(wrapped):
     """Wrapper for non-list/dict object to support map operation
 
     This class allows us to handle both:
     - "{manifest}"
     - "{manifest % '{rev}:{node}'}"
     - "{manifest.rev}"
 
     Unlike a hybrid, this does not simulate the behavior of the underling
-    value. Use unwrapvalue(), unwrapastype(), or unwraphybrid() to obtain
-    the inner object.
+    value.
     """
 
     def __init__(self, gen, key, value, makemap):
         self._gen = gen  # generator or function returning generator
         self._key = key
         self._value = value  # may be generator of strings
         self._makemap = makemap
 
     def tomap(self):
         return self._makemap(self._key)
 
     def itermaps(self):
         yield self.tomap()
 
     def show(self, context, mapping):
         # TODO: switch gen to (context, mapping) API?
         gen = self._gen
         if gen is None:
             return pycompat.bytestr(self._value)
         if callable(gen):
             return gen()
         return gen
 
+    def tovalue(self, context, mapping):
+        return _unthunk(context, mapping, self._value)
+
 def hybriddict(data, key='key', value='value', fmt=None, gen=None):
     """Wrap data to support both dict-like and string-like operations"""
     prefmt = pycompat.identity
     if fmt is None:
         fmt = '%s=%s'
         prefmt = pycompat.bytestr
     return hybrid(gen, data, lambda k: {key: k, value: data[k]},
                   lambda k: fmt % (prefmt(k), prefmt(data[k])))
 
 def hybridlist(data, name, fmt=None, gen=None):
     """Wrap data to support both list-like and string-like operations"""
     prefmt = pycompat.identity
     if fmt is None:
         fmt = '%s'
         prefmt = pycompat.bytestr
     return hybrid(gen, data, lambda x: {name: x}, lambda x: fmt % prefmt(x))
 
 def unwraphybrid(context, mapping, thing):
     """Return an object which can be stringified possibly by using a legacy
     template"""
     if not isinstance(thing, wrapped):
         return thing
     return thing.show(context, mapping)
 
 def unwrapvalue(context, mapping, thing):
     """Move the inner value object out of the wrapper"""
-    if not util.safehasattr(thing, '_value'):
+    if not isinstance(thing, wrapped):
         return thing
-    return thing._value
+    return thing.tovalue(context, mapping)
 
 def wraphybridvalue(container, key, value):
     """Wrap an element of hybrid container to be mappable
 
     The key is passed to the makemap function of the given container, which
     should be an item generated by iter(container).
     """
     makemap = getattr(container, '_makemap', None)
     if makemap is None:
         return value
     if util.safehasattr(value, '_makemap'):
         # a nested hybrid list/dict, which has its own way of map operation
         return value
     return mappable(None, key, value, makemap)
 
 def compatdict(context, mapping, name, data, key='key', value='value',
                fmt=None, plural=None, separator=' '):
     """Wrap data like hybriddict(), but also supports old-style list template
 
     This exists for backward compatibility with the old-style template. Use
     hybriddict() for new template keywords.
     """
     c = [{key: k, value: v} for k, v in data.iteritems()]
     f = _showcompatlist(context, mapping, name, c, plural, separator)
     return hybriddict(data, key=key, value=value, fmt=fmt, gen=f)
 
 def compatlist(context, mapping, name, data, element=None, fmt=None,
                plural=None, separator=' '):
     """Wrap data like hybridlist(), but also supports old-style list template
 
     This exists for backward compatibility with the old-style template. Use
     hybridlist() for new template keywords.
     """
     f = _showcompatlist(context, mapping, name, data, plural, separator)
     return hybridlist(data, name=element or name, fmt=fmt, gen=f)
 
 def _showcompatlist(context, mapping, name, values, plural=None, separator=' '):
     """Return a generator that renders old-style list template
 
     name is name of key in template map.
     values is list of strings or dicts.
     plural is plural of name, if not simply name + 's'.
     separator is used to join values as a string
 
     expansion works like this, given name 'foo'.
 
     if values is empty, expand 'no_foos'.
 
     if 'foo' not in template map, return values as a string,
     joined by 'separator'.
 
     expand 'start_foos'.
 
     for each value, expand 'foo'. if 'last_foo' in template
     map, expand it instead of 'foo' for last key.
 
     expand 'end_foos'.
     """
     if not plural:
         plural = name + 's'
     if not values:
         noname = 'no_' + plural
         if context.preload(noname):
             yield context.process(noname, mapping)
         return
     if not context.preload(name):
         if isinstance(values[0], bytes):
             yield separator.join(values)
         else:
             for v in values:
                 r = dict(v)
                 r.update(mapping)
                 yield r
         return
     startname = 'start_' + plural
     if context.preload(startname):
         yield context.process(startname, mapping)
     def one(v, tag=name):
         vmapping = {}
         try:
             vmapping.update(v)
         # Python 2 raises ValueError if the type of v is wrong. Python
         # 3 raises TypeError.
         except (AttributeError, TypeError, ValueError):
             try:
                 # Python 2 raises ValueError trying to destructure an e.g.
                 # bytes. Python 3 raises TypeError.
                 for a, b in v:
                     vmapping[a] = b
             except (TypeError, ValueError):
                 vmapping[name] = v
         vmapping = context.overlaymap(mapping, vmapping)
         return context.process(tag, vmapping)
     lastname = 'last_' + name
     if context.preload(lastname):
         last = values.pop()
     else:
         last = None
     for v in values:
         yield one(v)
     if last is not None:
         yield one(last, tag=lastname)
     endname = 'end_' + plural
     if context.preload(endname):
         yield context.process(endname, mapping)
 
 def flatten(context, mapping, thing):
     """Yield a single stream from a possibly nested set of iterators"""
     thing = unwraphybrid(context, mapping, thing)
     if isinstance(thing, bytes):
         yield thing
     elif isinstance(thing, str):
         # We can only hit this on Python 3, and it's here to guard
         # against infinite recursion.
         raise error.ProgrammingError('Mercurial IO including templates is done'
                                      ' with bytes, not strings, got %r' % thing)
     elif thing is None:
         pass
     elif not util.safehasattr(thing, '__iter__'):
         yield pycompat.bytestr(thing)
     else:
         for i in thing:
             i = unwraphybrid(context, mapping, i)
             if isinstance(i, bytes):
                 yield i
             elif i is None:
                 pass
             elif not util.safehasattr(i, '__iter__'):
                 yield pycompat.bytestr(i)
             else:
                 for j in flatten(context, mapping, i):
                     yield j
 
 def stringify(context, mapping, thing):
     """Turn values into bytes by converting into text and concatenating them"""
     if isinstance(thing, bytes):
         return thing  # retain localstr to be round-tripped
     return b''.join(flatten(context, mapping, thing))
 
 def findsymbolicname(arg):
     """Find symbolic name for the given compiled expression; returns None
     if nothing found reliably"""
     while True:
         func, data = arg
         if func is runsymbol:
             return data
         elif func is runfilter:
             arg = data[0]
         else:
             return None
 
 def _unthunk(context, mapping, thing):
     """Evaluate a lazy byte string into value"""
     if not isinstance(thing, types.GeneratorType):
         return thing
     return stringify(context, mapping, thing)
 
 def evalrawexp(context, mapping, arg):
     """Evaluate given argument as a bare template object which may require
     further processing (such as folding generator of strings)"""
     func, data = arg
     return func(context, mapping, data)
 
 def evalfuncarg(context, mapping, arg):
     """Evaluate given argument as value type"""
     return _unwrapvalue(context, mapping, evalrawexp(context, mapping, arg))
 
 # TODO: unify this with unwrapvalue() once the bug of templatefunc.join()
 # is fixed. we can't do that right now because join() has to take a generator
 # of byte strings as it is, not a lazy byte string.
 def _unwrapvalue(context, mapping, thing):
     thing = unwrapvalue(context, mapping, thing)
     # evalrawexp() may return string, generator of strings or arbitrary object
     # such as date tuple, but filter does not want generator.
     return _unthunk(context, mapping, thing)
 
 def evalboolean(context, mapping, arg):
     """Evaluate given argument as boolean, but also takes boolean literals"""
     func, data = arg
     if func is runsymbol:
         thing = func(context, mapping, data, default=None)
         if thing is None:
             # not a template keyword, takes as a boolean literal
             thing = stringutil.parsebool(data)
     else:
         thing = func(context, mapping, data)
     thing = unwrapvalue(context, mapping, thing)
     if isinstance(thing, bool):
         return thing
     # other objects are evaluated as strings, which means 0 is True, but
     # empty dict/list should be False as they are expected to be ''
     return bool(stringify(context, mapping, thing))
 
 def evaldate(context, mapping, arg, err=None):
     """Evaluate given argument as a date tuple or a date string; returns
     a (unixtime, offset) tuple"""
     thing = evalrawexp(context, mapping, arg)
     return unwrapdate(context, mapping, thing, err)
 
 def unwrapdate(context, mapping, thing, err=None):
     thing = _unwrapvalue(context, mapping, thing)
     try:
         return dateutil.parsedate(thing)
     except AttributeError:
         raise error.ParseError(err or _('not a date tuple nor a string'))
     except error.ParseError:
         if not err:
             raise
         raise error.ParseError(err)
 
 def evalinteger(context, mapping, arg, err=None):
     thing = evalrawexp(context, mapping, arg)
     return unwrapinteger(context, mapping, thing, err)
 
 def unwrapinteger(context, mapping, thing, err=None):
     thing = _unwrapvalue(context, mapping, thing)
     try:
         return int(thing)
     except (TypeError, ValueError):
         raise error.ParseError(err or _('not an integer'))
 
 def evalstring(context, mapping, arg):
     return stringify(context, mapping, evalrawexp(context, mapping, arg))
 
 def evalstringliteral(context, mapping, arg):
     """Evaluate given argument as string template, but returns symbol name
     if it is unknown"""
     func, data = arg
     if func is runsymbol:
         thing = func(context, mapping, data, default=data)
     else:
         thing = func(context, mapping, data)
     return stringify(context, mapping, thing)
 
 _unwrapfuncbytype = {
     None: _unwrapvalue,
     bytes: stringify,
     date: unwrapdate,
     int: unwrapinteger,
 }
 
 def unwrapastype(context, mapping, thing, typ):
     """Move the inner value object out of the wrapper and coerce its type"""
     try:
         f = _unwrapfuncbytype[typ]
     except KeyError:
         raise error.ProgrammingError('invalid type specified: %r' % typ)
     return f(context, mapping, thing)
 
 def runinteger(context, mapping, data):
     return int(data)
 
 def runstring(context, mapping, data):
     return data
 
 def _recursivesymbolblocker(key):
     def showrecursion(**args):
         raise error.Abort(_("recursive reference '%s' in template") % key)
     return showrecursion
 
 def runsymbol(context, mapping, key, default=''):
     v = context.symbol(mapping, key)
     if v is None:
         # put poison to cut recursion. we can't move this to parsing phase
         # because "x = {x}" is allowed if "x" is a keyword. (issue4758)
         safemapping = mapping.copy()
         safemapping[key] = _recursivesymbolblocker(key)
         try:
             v = context.process(key, safemapping)
         except TemplateNotFound:
             v = default
     if callable(v) and getattr(v, '_requires', None) is None:
         # old templatekw: expand all keywords and resources
         # (TODO: deprecate this after porting web template keywords to new API)
         props = {k: context._resources.lookup(context, mapping, k)
                  for k in context._resources.knownkeys()}
         # pass context to _showcompatlist() through templatekw._showlist()
         props['templ'] = context
         props.update(mapping)
         return v(**pycompat.strkwargs(props))
     if callable(v):
         # new templatekw
         try:
             return v(context, mapping)
         except ResourceUnavailable:
             # unsupported keyword is mapped to empty just like unknown keyword
             return None
     return v
 
 def runtemplate(context, mapping, template):
     for arg in template:
         yield evalrawexp(context, mapping, arg)
 
 def runfilter(context, mapping, data):
     arg, filt = data
     thing = evalrawexp(context, mapping, arg)
     intype = getattr(filt, '_intype', None)
     try:
         thing = unwrapastype(context, mapping, thing, intype)
         return filt(thing)
     except error.ParseError as e:
         raise error.ParseError(bytes(e), hint=_formatfiltererror(arg, filt))
 
 def _formatfiltererror(arg, filt):
     fn = pycompat.sysbytes(filt.__name__)
     sym = findsymbolicname(arg)
     if not sym:
         return _("incompatible use of template filter '%s'") % fn
     return (_("template filter '%s' is not compatible with keyword '%s'")
             % (fn, sym))
 
 def runmap(context, mapping, data):
     darg, targ = data
     d = evalrawexp(context, mapping, darg)
     if util.safehasattr(d, 'itermaps'):
         diter = d.itermaps()
     else:
         try:
             diter = iter(d)
         except TypeError:
             sym = findsymbolicname(darg)
             if sym:
                 raise error.ParseError(_("keyword '%s' is not iterable") % sym)
             else:
                 raise error.ParseError(_("%r is not iterable") % d)
 
     for i, v in enumerate(diter):
         if isinstance(v, dict):
             lm = context.overlaymap(mapping, v)
             lm['index'] = i
             yield evalrawexp(context, lm, targ)
         else:
             # v is not an iterable of dicts, this happen when 'key'
             # has been fully expanded already and format is useless.
             # If so, return the expanded value.
             yield v
 
 def runmember(context, mapping, data):
     darg, memb = data
     d = evalrawexp(context, mapping, darg)
     if util.safehasattr(d, 'tomap'):
         lm = context.overlaymap(mapping, d.tomap())
         return runsymbol(context, lm, memb)
     if util.safehasattr(d, 'get'):
         return getdictitem(d, memb)
 
     sym = findsymbolicname(darg)
     if sym:
         raise error.ParseError(_("keyword '%s' has no member") % sym)
     else:
         raise error.ParseError(_("%r has no member") % pycompat.bytestr(d))
 
 def runnegate(context, mapping, data):
     data = evalinteger(context, mapping, data,
                        _('negation needs an integer argument'))
     return -data
 
 def runarithmetic(context, mapping, data):
     func, left, right = data
     left = evalinteger(context, mapping, left,
                        _('arithmetic only defined on integers'))
     right = evalinteger(context, mapping, right,
                         _('arithmetic only defined on integers'))
     try:
         return func(left, right)
     except ZeroDivisionError:
         raise error.Abort(_('division by zero is not defined'))
 
 def getdictitem(dictarg, key):
     val = dictarg.get(key)
     if val is None:
         return
     return wraphybridvalue(dictarg, key, val)