templater: add class representing a nested mappings

The mappinggenerator class is necessary to fix hgweb bugs without BC. The
mappinglist is for nested formatter items. They are similar, so factored
out the base class. The mappinglist could be implemented by using the
mappinggenerator, but we'll probably need a direct access to the raw list,
so they are implemented as separate classes.

Note that tovalue() isn't conforming to the spec yet in that it may return
a list of dicts containing unprintable resources. This problem will be
fixed later.

Tests will be added by subsequent patches.

mercurial/templater.py

@@ -1,907 +1,911 b''
 # templater.py - template expansion for output
 #
 # 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.
 
 """Slightly complicated template engine for commands and hgweb
 
 This module provides low-level interface to the template engine. See the
 formatter and cmdutil modules if you are looking for high-level functions
 such as ``cmdutil.rendertemplate(ctx, tmpl)``.
 
 Internal Data Types
 -------------------
 
 Template keywords and functions take a dictionary of current symbols and
 resources (a "mapping") and return result. Inputs and outputs must be one
 of the following data types:
 
 bytes
     a byte string, which is generally a human-readable text in local encoding.
 
 generator
     a lazily-evaluated byte string, which is a possibly nested generator of
     values of any printable types, and  will be folded by ``stringify()``
     or ``flatten()``.
 
     BUG: hgweb overloads this type for mappings (i.e. some hgweb keywords
     returns a generator of dicts.)
 
 None
     sometimes represents an empty value, which can be stringified to ''.
 
 True, False, int, float
     can be stringified as such.
 
 date tuple
     a (unixtime, offset) tuple, which produces no meaningful output by itself.
 
 hybrid
     represents a list/dict of printable values, which can also be converted
     to mappings by % operator.
 
 mappable
     represents a scalar printable value, also supports % operator.
+
+mappinggenerator, mappinglist
+    represents mappings (i.e. a list of dicts), which may have default
+    output format.
 """
 
 from __future__ import absolute_import, print_function
 
 import abc
 import os
 
 from .i18n import _
 from . import (
     config,
     encoding,
     error,
     parser,
     pycompat,
     templatefilters,
     templatefuncs,
     templateutil,
     util,
 )
 from .utils import (
     stringutil,
 )
 
 # template parsing
 
 elements = {
     # token-type: binding-strength, primary, prefix, infix, suffix
     "(": (20, None, ("group", 1, ")"), ("func", 1, ")"), None),
     ".": (18, None, None, (".", 18), None),
     "%": (15, None, None, ("%", 15), None),
     "|": (15, None, None, ("|", 15), None),
     "*": (5, None, None, ("*", 5), None),
     "/": (5, None, None, ("/", 5), None),
     "+": (4, None, None, ("+", 4), None),
     "-": (4, None, ("negate", 19), ("-", 4), None),
     "=": (3, None, None, ("keyvalue", 3), None),
     ",": (2, None, None, ("list", 2), None),
     ")": (0, None, None, None, None),
     "integer": (0, "integer", None, None, None),
     "symbol": (0, "symbol", None, None, None),
     "string": (0, "string", None, None, None),
     "template": (0, "template", None, None, None),
     "end": (0, None, None, None, None),
 }
 
 def tokenize(program, start, end, term=None):
     """Parse a template expression into a stream of tokens, which must end
     with term if specified"""
     pos = start
     program = pycompat.bytestr(program)
     while pos < end:
         c = program[pos]
         if c.isspace(): # skip inter-token whitespace
             pass
         elif c in "(=,).%|+-*/": # handle simple operators
             yield (c, None, pos)
         elif c in '"\'': # handle quoted templates
             s = pos + 1
             data, pos = _parsetemplate(program, s, end, c)
             yield ('template', data, s)
             pos -= 1
         elif c == 'r' and program[pos:pos + 2] in ("r'", 'r"'):
             # handle quoted strings
             c = program[pos + 1]
             s = pos = pos + 2
             while pos < end: # find closing quote
                 d = program[pos]
                 if d == '\\': # skip over escaped characters
                     pos += 2
                     continue
                 if d == c:
                     yield ('string', program[s:pos], s)
                     break
                 pos += 1
             else:
                 raise error.ParseError(_("unterminated string"), s)
         elif c.isdigit():
             s = pos
             while pos < end:
                 d = program[pos]
                 if not d.isdigit():
                     break
                 pos += 1
             yield ('integer', program[s:pos], s)
             pos -= 1
         elif (c == '\\' and program[pos:pos + 2] in (br"\'", br'\"')
               or c == 'r' and program[pos:pos + 3] in (br"r\'", br'r\"')):
             # handle escaped quoted strings for compatibility with 2.9.2-3.4,
             # where some of nested templates were preprocessed as strings and
             # then compiled. therefore, \"...\" was allowed. (issue4733)
             #
             # processing flow of _evalifliteral() at 5ab28a2e9962:
             # outer template string    -> stringify()  -> compiletemplate()
             # ------------------------    ------------    ------------------
             # {f("\\\\ {g(\"\\\"\")}"}    \\ {g("\"")}    [r'\\', {g("\"")}]
             #             ~~~~~~~~
             #             escaped quoted string
             if c == 'r':
                 pos += 1
                 token = 'string'
             else:
                 token = 'template'
             quote = program[pos:pos + 2]
             s = pos = pos + 2
             while pos < end: # find closing escaped quote
                 if program.startswith('\\\\\\', pos, end):
                     pos += 4 # skip over double escaped characters
                     continue
                 if program.startswith(quote, pos, end):
                     # interpret as if it were a part of an outer string
                     data = parser.unescapestr(program[s:pos])
                     if token == 'template':
                         data = _parsetemplate(data, 0, len(data))[0]
                     yield (token, data, s)
                     pos += 1
                     break
                 pos += 1
             else:
                 raise error.ParseError(_("unterminated string"), s)
         elif c.isalnum() or c in '_':
             s = pos
             pos += 1
             while pos < end: # find end of symbol
                 d = program[pos]
                 if not (d.isalnum() or d == "_"):
                     break
                 pos += 1
             sym = program[s:pos]
             yield ('symbol', sym, s)
             pos -= 1
         elif c == term:
             yield ('end', None, pos)
             return
         else:
             raise error.ParseError(_("syntax error"), pos)
         pos += 1
     if term:
         raise error.ParseError(_("unterminated template expansion"), start)
     yield ('end', None, pos)
 
 def _parsetemplate(tmpl, start, stop, quote=''):
     r"""
     >>> _parsetemplate(b'foo{bar}"baz', 0, 12)
     ([('string', 'foo'), ('symbol', 'bar'), ('string', '"baz')], 12)
     >>> _parsetemplate(b'foo{bar}"baz', 0, 12, quote=b'"')
     ([('string', 'foo'), ('symbol', 'bar')], 9)
     >>> _parsetemplate(b'foo"{bar}', 0, 9, quote=b'"')
     ([('string', 'foo')], 4)
     >>> _parsetemplate(br'foo\"bar"baz', 0, 12, quote=b'"')
     ([('string', 'foo"'), ('string', 'bar')], 9)
     >>> _parsetemplate(br'foo\\"bar', 0, 10, quote=b'"')
     ([('string', 'foo\\')], 6)
     """
     parsed = []
     for typ, val, pos in _scantemplate(tmpl, start, stop, quote):
         if typ == 'string':
             parsed.append((typ, val))
         elif typ == 'template':
             parsed.append(val)
         elif typ == 'end':
             return parsed, pos
         else:
             raise error.ProgrammingError('unexpected type: %s' % typ)
     raise error.ProgrammingError('unterminated scanning of template')
 
 def scantemplate(tmpl, raw=False):
     r"""Scan (type, start, end) positions of outermost elements in template
 
     If raw=True, a backslash is not taken as an escape character just like
     r'' string in Python. Note that this is different from r'' literal in
     template in that no template fragment can appear in r'', e.g. r'{foo}'
     is a literal '{foo}', but ('{foo}', raw=True) is a template expression
     'foo'.
 
     >>> list(scantemplate(b'foo{bar}"baz'))
     [('string', 0, 3), ('template', 3, 8), ('string', 8, 12)]
     >>> list(scantemplate(b'outer{"inner"}outer'))
     [('string', 0, 5), ('template', 5, 14), ('string', 14, 19)]
     >>> list(scantemplate(b'foo\\{escaped}'))
     [('string', 0, 5), ('string', 5, 13)]
     >>> list(scantemplate(b'foo\\{escaped}', raw=True))
     [('string', 0, 4), ('template', 4, 13)]
     """
     last = None
     for typ, val, pos in _scantemplate(tmpl, 0, len(tmpl), raw=raw):
         if last:
             yield last + (pos,)
         if typ == 'end':
             return
         else:
             last = (typ, pos)
     raise error.ProgrammingError('unterminated scanning of template')
 
 def _scantemplate(tmpl, start, stop, quote='', raw=False):
     """Parse template string into chunks of strings and template expressions"""
     sepchars = '{' + quote
     unescape = [parser.unescapestr, pycompat.identity][raw]
     pos = start
     p = parser.parser(elements)
     try:
         while pos < stop:
             n = min((tmpl.find(c, pos, stop) for c in sepchars),
                     key=lambda n: (n < 0, n))
             if n < 0:
                 yield ('string', unescape(tmpl[pos:stop]), pos)
                 pos = stop
                 break
             c = tmpl[n:n + 1]
             bs = 0  # count leading backslashes
             if not raw:
                 bs = (n - pos) - len(tmpl[pos:n].rstrip('\\'))
             if bs % 2 == 1:
                 # escaped (e.g. '\{', '\\\{', but not '\\{')
                 yield ('string', unescape(tmpl[pos:n - 1]) + c, pos)
                 pos = n + 1
                 continue
             if n > pos:
                 yield ('string', unescape(tmpl[pos:n]), pos)
             if c == quote:
                 yield ('end', None, n + 1)
                 return
 
             parseres, pos = p.parse(tokenize(tmpl, n + 1, stop, '}'))
             if not tmpl.startswith('}', pos):
                 raise error.ParseError(_("invalid token"), pos)
             yield ('template', parseres, n)
             pos += 1
 
         if quote:
             raise error.ParseError(_("unterminated string"), start)
     except error.ParseError as inst:
         if len(inst.args) > 1:  # has location
             loc = inst.args[1]
             # Offset the caret location by the number of newlines before the
             # location of the error, since we will replace one-char newlines
             # with the two-char literal r'\n'.
             offset = tmpl[:loc].count('\n')
             tmpl = tmpl.replace('\n', br'\n')
             # We want the caret to point to the place in the template that
             # failed to parse, but in a hint we get a open paren at the
             # start. Therefore, we print "loc + 1" spaces (instead of "loc")
             # to line up the caret with the location of the error.
             inst.hint = (tmpl + '\n'
                          + ' ' * (loc + 1 + offset) + '^ ' + _('here'))
         raise
     yield ('end', None, pos)
 
 def _unnesttemplatelist(tree):
     """Expand list of templates to node tuple
 
     >>> def f(tree):
     ...     print(pycompat.sysstr(prettyformat(_unnesttemplatelist(tree))))
     >>> f((b'template', []))
     (string '')
     >>> f((b'template', [(b'string', b'foo')]))
     (string 'foo')
     >>> f((b'template', [(b'string', b'foo'), (b'symbol', b'rev')]))
     (template
       (string 'foo')
       (symbol 'rev'))
     >>> f((b'template', [(b'symbol', b'rev')]))  # template(rev) -> str
     (template
       (symbol 'rev'))
     >>> f((b'template', [(b'template', [(b'string', b'foo')])]))
     (string 'foo')
     """
     if not isinstance(tree, tuple):
         return tree
     op = tree[0]
     if op != 'template':
         return (op,) + tuple(_unnesttemplatelist(x) for x in tree[1:])
 
     assert len(tree) == 2
     xs = tuple(_unnesttemplatelist(x) for x in tree[1])
     if not xs:
         return ('string', '')  # empty template ""
     elif len(xs) == 1 and xs[0][0] == 'string':
         return xs[0]  # fast path for string with no template fragment "x"
     else:
         return (op,) + xs
 
 def parse(tmpl):
     """Parse template string into tree"""
     parsed, pos = _parsetemplate(tmpl, 0, len(tmpl))
     assert pos == len(tmpl), 'unquoted template should be consumed'
     return _unnesttemplatelist(('template', parsed))
 
 def _parseexpr(expr):
     """Parse a template expression into tree
 
     >>> _parseexpr(b'"foo"')
     ('string', 'foo')
     >>> _parseexpr(b'foo(bar)')
     ('func', ('symbol', 'foo'), ('symbol', 'bar'))
     >>> _parseexpr(b'foo(')
     Traceback (most recent call last):
       ...
     ParseError: ('not a prefix: end', 4)
     >>> _parseexpr(b'"foo" "bar"')
     Traceback (most recent call last):
       ...
     ParseError: ('invalid token', 7)
     """
     p = parser.parser(elements)
     tree, pos = p.parse(tokenize(expr, 0, len(expr)))
     if pos != len(expr):
         raise error.ParseError(_('invalid token'), pos)
     return _unnesttemplatelist(tree)
 
 def prettyformat(tree):
     return parser.prettyformat(tree, ('integer', 'string', 'symbol'))
 
 def compileexp(exp, context, curmethods):
     """Compile parsed template tree to (func, data) pair"""
     if not exp:
         raise error.ParseError(_("missing argument"))
     t = exp[0]
     if t in curmethods:
         return curmethods[t](exp, context)
     raise error.ParseError(_("unknown method '%s'") % t)
 
 # template evaluation
 
 def getsymbol(exp):
     if exp[0] == 'symbol':
         return exp[1]
     raise error.ParseError(_("expected a symbol, got '%s'") % exp[0])
 
 def getlist(x):
     if not x:
         return []
     if x[0] == 'list':
         return getlist(x[1]) + [x[2]]
     return [x]
 
 def gettemplate(exp, context):
     """Compile given template tree or load named template from map file;
     returns (func, data) pair"""
     if exp[0] in ('template', 'string'):
         return compileexp(exp, context, methods)
     if exp[0] == 'symbol':
         # unlike runsymbol(), here 'symbol' is always taken as template name
         # even if it exists in mapping. this allows us to override mapping
         # by web templates, e.g. 'changelogtag' is redefined in map file.
         return context._load(exp[1])
     raise error.ParseError(_("expected template specifier"))
 
 def _runrecursivesymbol(context, mapping, key):
     raise error.Abort(_("recursive reference '%s' in template") % key)
 
 def buildtemplate(exp, context):
     ctmpl = [compileexp(e, context, methods) for e in exp[1:]]
     return (templateutil.runtemplate, ctmpl)
 
 def buildfilter(exp, context):
     n = getsymbol(exp[2])
     if n in context._filters:
         filt = context._filters[n]
         arg = compileexp(exp[1], context, methods)
         return (templateutil.runfilter, (arg, filt))
     if n in context._funcs:
         f = context._funcs[n]
         args = _buildfuncargs(exp[1], context, methods, n, f._argspec)
         return (f, args)
     raise error.ParseError(_("unknown function '%s'") % n)
 
 def buildmap(exp, context):
     darg = compileexp(exp[1], context, methods)
     targ = gettemplate(exp[2], context)
     return (templateutil.runmap, (darg, targ))
 
 def buildmember(exp, context):
     darg = compileexp(exp[1], context, methods)
     memb = getsymbol(exp[2])
     return (templateutil.runmember, (darg, memb))
 
 def buildnegate(exp, context):
     arg = compileexp(exp[1], context, exprmethods)
     return (templateutil.runnegate, arg)
 
 def buildarithmetic(exp, context, func):
     left = compileexp(exp[1], context, exprmethods)
     right = compileexp(exp[2], context, exprmethods)
     return (templateutil.runarithmetic, (func, left, right))
 
 def buildfunc(exp, context):
     n = getsymbol(exp[1])
     if n in context._funcs:
         f = context._funcs[n]
         args = _buildfuncargs(exp[2], context, exprmethods, n, f._argspec)
         return (f, args)
     if n in context._filters:
         args = _buildfuncargs(exp[2], context, exprmethods, n, argspec=None)
         if len(args) != 1:
             raise error.ParseError(_("filter %s expects one argument") % n)
         f = context._filters[n]
         return (templateutil.runfilter, (args[0], f))
     raise error.ParseError(_("unknown function '%s'") % n)
 
 def _buildfuncargs(exp, context, curmethods, funcname, argspec):
     """Compile parsed tree of function arguments into list or dict of
     (func, data) pairs
 
     >>> context = engine(lambda t: (templateutil.runsymbol, t))
     >>> def fargs(expr, argspec):
     ...     x = _parseexpr(expr)
     ...     n = getsymbol(x[1])
     ...     return _buildfuncargs(x[2], context, exprmethods, n, argspec)
     >>> list(fargs(b'a(l=1, k=2)', b'k l m').keys())
     ['l', 'k']
     >>> args = fargs(b'a(opts=1, k=2)', b'**opts')
     >>> list(args.keys()), list(args[b'opts'].keys())
     (['opts'], ['opts', 'k'])
     """
     def compiledict(xs):
         return util.sortdict((k, compileexp(x, context, curmethods))
                              for k, x in xs.iteritems())
     def compilelist(xs):
         return [compileexp(x, context, curmethods) for x in xs]
 
     if not argspec:
         # filter or function with no argspec: return list of positional args
         return compilelist(getlist(exp))
 
     # function with argspec: return dict of named args
     _poskeys, varkey, _keys, optkey = argspec = parser.splitargspec(argspec)
     treeargs = parser.buildargsdict(getlist(exp), funcname, argspec,
                                     keyvaluenode='keyvalue', keynode='symbol')
     compargs = util.sortdict()
     if varkey:
         compargs[varkey] = compilelist(treeargs.pop(varkey))
     if optkey:
         compargs[optkey] = compiledict(treeargs.pop(optkey))
     compargs.update(compiledict(treeargs))
     return compargs
 
 def buildkeyvaluepair(exp, content):
     raise error.ParseError(_("can't use a key-value pair in this context"))
 
 # methods to interpret function arguments or inner expressions (e.g. {_(x)})
 exprmethods = {
     "integer": lambda e, c: (templateutil.runinteger, e[1]),
     "string": lambda e, c: (templateutil.runstring, e[1]),
     "symbol": lambda e, c: (templateutil.runsymbol, e[1]),
     "template": buildtemplate,
     "group": lambda e, c: compileexp(e[1], c, exprmethods),
     ".": buildmember,
     "|": buildfilter,
     "%": buildmap,
     "func": buildfunc,
     "keyvalue": buildkeyvaluepair,
     "+": lambda e, c: buildarithmetic(e, c, lambda a, b: a + b),
     "-": lambda e, c: buildarithmetic(e, c, lambda a, b: a - b),
     "negate": buildnegate,
     "*": lambda e, c: buildarithmetic(e, c, lambda a, b: a * b),
     "/": lambda e, c: buildarithmetic(e, c, lambda a, b: a // b),
     }
 
 # methods to interpret top-level template (e.g. {x}, {x|_}, {x % "y"})
 methods = exprmethods.copy()
 methods["integer"] = exprmethods["symbol"]  # '{1}' as variable
 
 class _aliasrules(parser.basealiasrules):
     """Parsing and expansion rule set of template aliases"""
     _section = _('template alias')
     _parse = staticmethod(_parseexpr)
 
     @staticmethod
     def _trygetfunc(tree):
         """Return (name, args) if tree is func(...) or ...|filter; otherwise
         None"""
         if tree[0] == 'func' and tree[1][0] == 'symbol':
             return tree[1][1], getlist(tree[2])
         if tree[0] == '|' and tree[2][0] == 'symbol':
             return tree[2][1], [tree[1]]
 
 def expandaliases(tree, aliases):
     """Return new tree of aliases are expanded"""
     aliasmap = _aliasrules.buildmap(aliases)
     return _aliasrules.expand(aliasmap, tree)
 
 # template engine
 
 def unquotestring(s):
     '''unwrap quotes if any; otherwise returns unmodified string'''
     if len(s) < 2 or s[0] not in "'\"" or s[0] != s[-1]:
         return s
     return s[1:-1]
 
 class resourcemapper(object):
     """Mapper of internal template resources"""
 
     __metaclass__ = abc.ABCMeta
 
     @abc.abstractmethod
     def availablekeys(self, context, mapping):
         """Return a set of available resource keys based on the given mapping"""
 
     @abc.abstractmethod
     def knownkeys(self):
         """Return a set of supported resource keys"""
 
     @abc.abstractmethod
     def lookup(self, context, mapping, key):
         """Return a resource for the key if available; otherwise None"""
 
     @abc.abstractmethod
     def populatemap(self, context, origmapping, newmapping):
         """Return a dict of additional mapping items which should be paired
         with the given new mapping"""
 
 class nullresourcemapper(resourcemapper):
     def availablekeys(self, context, mapping):
         return set()
 
     def knownkeys(self):
         return set()
 
     def lookup(self, context, mapping, key):
         return None
 
     def populatemap(self, context, origmapping, newmapping):
         return {}
 
 class engine(object):
     '''template expansion engine.
 
     template expansion works like this. a map file contains key=value
     pairs. if value is quoted, it is treated as string. otherwise, it
     is treated as name of template file.
 
     templater is asked to expand a key in map. it looks up key, and
     looks for strings like this: {foo}. it expands {foo} by looking up
     foo in map, and substituting it. expansion is recursive: it stops
     when there is no more {foo} to replace.
 
     expansion also allows formatting and filtering.
 
     format uses key to expand each item in list. syntax is
     {key%format}.
 
     filter uses function to transform value. syntax is
     {key|filter1|filter2|...}.'''
 
     def __init__(self, loader, filters=None, defaults=None, resources=None,
                  aliases=()):
         self._loader = loader
         if filters is None:
             filters = {}
         self._filters = filters
         self._funcs = templatefuncs.funcs  # make this a parameter if needed
         if defaults is None:
             defaults = {}
         if resources is None:
             resources = nullresourcemapper()
         self._defaults = defaults
         self._resources = resources
         self._aliasmap = _aliasrules.buildmap(aliases)
         self._cache = {}  # key: (func, data)
         self._tmplcache = {}  # literal template: (func, data)
 
     def overlaymap(self, origmapping, newmapping):
         """Create combined mapping from the original mapping and partial
         mapping to override the original"""
         # do not copy symbols which overrides the defaults depending on
         # new resources, so the defaults will be re-evaluated (issue5612)
         knownres = self._resources.knownkeys()
         newres = self._resources.availablekeys(self, newmapping)
         mapping = {k: v for k, v in origmapping.iteritems()
                    if (k in knownres  # not a symbol per self.symbol()
                        or newres.isdisjoint(self._defaultrequires(k)))}
         mapping.update(newmapping)
         mapping.update(
             self._resources.populatemap(self, origmapping, newmapping))
         return mapping
 
     def _defaultrequires(self, key):
         """Resource keys required by the specified default symbol function"""
         v = self._defaults.get(key)
         if v is None or not callable(v):
             return ()
         return getattr(v, '_requires', ())
 
     def symbol(self, mapping, key):
         """Resolve symbol to value or function; None if nothing found"""
         v = None
         if key not in self._resources.knownkeys():
             v = mapping.get(key)
         if v is None:
             v = self._defaults.get(key)
         return v
 
     def resource(self, mapping, key):
         """Return internal data (e.g. cache) used for keyword/function
         evaluation"""
         v = self._resources.lookup(self, mapping, key)
         if v is None:
             raise templateutil.ResourceUnavailable(
                 _('template resource not available: %s') % key)
         return v
 
     def _load(self, t):
         '''load, parse, and cache a template'''
         if t not in self._cache:
             # put poison to cut recursion while compiling 't'
             self._cache[t] = (_runrecursivesymbol, t)
             try:
                 x = parse(self._loader(t))
                 if self._aliasmap:
                     x = _aliasrules.expand(self._aliasmap, x)
                 self._cache[t] = compileexp(x, self, methods)
             except: # re-raises
                 del self._cache[t]
                 raise
         return self._cache[t]
 
     def _parse(self, tmpl):
         """Parse and cache a literal template"""
         if tmpl not in self._tmplcache:
             x = parse(tmpl)
             self._tmplcache[tmpl] = compileexp(x, self, methods)
         return self._tmplcache[tmpl]
 
     def preload(self, t):
         """Load, parse, and cache the specified template if available"""
         try:
             self._load(t)
             return True
         except templateutil.TemplateNotFound:
             return False
 
     def process(self, t, mapping):
         '''Perform expansion. t is name of map element to expand.
         mapping contains added elements for use during expansion. Is a
         generator.'''
         func, data = self._load(t)
         return self._expand(func, data, mapping)
 
     def expand(self, tmpl, mapping):
         """Perform expansion over a literal template
 
         No user aliases will be expanded since this is supposed to be called
         with an internal template string.
         """
         func, data = self._parse(tmpl)
         return self._expand(func, data, mapping)
 
     def _expand(self, func, data, mapping):
         # populate additional items only if they don't exist in the given
         # mapping. this is slightly different from overlaymap() because the
         # initial 'revcache' may contain pre-computed items.
         extramapping = self._resources.populatemap(self, {}, mapping)
         if extramapping:
             extramapping.update(mapping)
             mapping = extramapping
         return templateutil.flatten(self, mapping, func(self, mapping, data))
 
 engines = {'default': engine}
 
 def stylelist():
     paths = templatepaths()
     if not paths:
         return _('no templates found, try `hg debuginstall` for more info')
     dirlist = os.listdir(paths[0])
     stylelist = []
     for file in dirlist:
         split = file.split(".")
         if split[-1] in ('orig', 'rej'):
             continue
         if split[0] == "map-cmdline":
             stylelist.append(split[1])
     return ", ".join(sorted(stylelist))
 
 def _readmapfile(mapfile):
     """Load template elements from the given map file"""
     if not os.path.exists(mapfile):
         raise error.Abort(_("style '%s' not found") % mapfile,
                           hint=_("available styles: %s") % stylelist())
 
     base = os.path.dirname(mapfile)
     conf = config.config(includepaths=templatepaths())
     conf.read(mapfile, remap={'': 'templates'})
 
     cache = {}
     tmap = {}
     aliases = []
 
     val = conf.get('templates', '__base__')
     if val and val[0] not in "'\"":
         # treat as a pointer to a base class for this style
         path = util.normpath(os.path.join(base, val))
 
         # fallback check in template paths
         if not os.path.exists(path):
             for p in templatepaths():
                 p2 = util.normpath(os.path.join(p, val))
                 if os.path.isfile(p2):
                     path = p2
                     break
                 p3 = util.normpath(os.path.join(p2, "map"))
                 if os.path.isfile(p3):
                     path = p3
                     break
 
         cache, tmap, aliases = _readmapfile(path)
 
     for key, val in conf['templates'].items():
         if not val:
             raise error.ParseError(_('missing value'),
                                    conf.source('templates', key))
         if val[0] in "'\"":
             if val[0] != val[-1]:
                 raise error.ParseError(_('unmatched quotes'),
                                        conf.source('templates', key))
             cache[key] = unquotestring(val)
         elif key != '__base__':
             val = 'default', val
             if ':' in val[1]:
                 val = val[1].split(':', 1)
             tmap[key] = val[0], os.path.join(base, val[1])
     aliases.extend(conf['templatealias'].items())
     return cache, tmap, aliases
 
 class templater(object):
 
     def __init__(self, filters=None, defaults=None, resources=None,
                  cache=None, aliases=(), minchunk=1024, maxchunk=65536):
         """Create template engine optionally with preloaded template fragments
 
         - ``filters``: a dict of functions to transform a value into another.
         - ``defaults``: a dict of symbol values/functions; may be overridden
           by a ``mapping`` dict.
         - ``resources``: a resourcemapper object to look up internal data
           (e.g. cache), inaccessible from user template.
         - ``cache``: a dict of preloaded template fragments.
         - ``aliases``: a list of alias (name, replacement) pairs.
 
         self.cache may be updated later to register additional template
         fragments.
         """
         if filters is None:
             filters = {}
         if defaults is None:
             defaults = {}
         if cache is None:
             cache = {}
         self.cache = cache.copy()
         self.map = {}
         self.filters = templatefilters.filters.copy()
         self.filters.update(filters)
         self.defaults = defaults
         self._resources = resources
         self._aliases = aliases
         self.minchunk, self.maxchunk = minchunk, maxchunk
         self.ecache = {}
 
     @classmethod
     def frommapfile(cls, mapfile, filters=None, defaults=None, resources=None,
                     cache=None, minchunk=1024, maxchunk=65536):
         """Create templater from the specified map file"""
         t = cls(filters, defaults, resources, cache, [], minchunk, maxchunk)
         cache, tmap, aliases = _readmapfile(mapfile)
         t.cache.update(cache)
         t.map = tmap
         t._aliases = aliases
         return t
 
     def __contains__(self, key):
         return key in self.cache or key in self.map
 
     def load(self, t):
         '''Get the template for the given template name. Use a local cache.'''
         if t not in self.cache:
             try:
                 self.cache[t] = util.readfile(self.map[t][1])
             except KeyError as inst:
                 raise templateutil.TemplateNotFound(
                     _('"%s" not in template map') % inst.args[0])
             except IOError as inst:
                 reason = (_('template file %s: %s')
                           % (self.map[t][1],
                              stringutil.forcebytestr(inst.args[1])))
                 raise IOError(inst.args[0], encoding.strfromlocal(reason))
         return self.cache[t]
 
     def renderdefault(self, mapping):
         """Render the default unnamed template and return result as string"""
         return self.render('', mapping)
 
     def render(self, t, mapping):
         """Render the specified named template and return result as string"""
         return b''.join(self.generate(t, mapping))
 
     def generate(self, t, mapping):
         """Return a generator that renders the specified named template and
         yields chunks"""
         ttype = t in self.map and self.map[t][0] or 'default'
         if ttype not in self.ecache:
             try:
                 ecls = engines[ttype]
             except KeyError:
                 raise error.Abort(_('invalid template engine: %s') % ttype)
             self.ecache[ttype] = ecls(self.load, self.filters, self.defaults,
                                       self._resources, self._aliases)
         proc = self.ecache[ttype]
 
         stream = proc.process(t, mapping)
         if self.minchunk:
             stream = util.increasingchunks(stream, min=self.minchunk,
                                            max=self.maxchunk)
         return stream
 
 def templatepaths():
     '''return locations used for template files.'''
     pathsrel = ['templates']
     paths = [os.path.normpath(os.path.join(util.datapath, f))
              for f in pathsrel]
     return [p for p in paths if os.path.isdir(p)]
 
 def templatepath(name):
     '''return location of template file. returns None if not found.'''
     for p in templatepaths():
         f = os.path.join(p, name)
         if os.path.exists(f):
             return f
     return None
 
 def stylemap(styles, paths=None):
     """Return path to mapfile for a given style.
 
     Searches mapfile in the following locations:
     1. templatepath/style/map
     2. templatepath/map-style
     3. templatepath/map
     """
 
     if paths is None:
         paths = templatepaths()
     elif isinstance(paths, bytes):
         paths = [paths]
 
     if isinstance(styles, bytes):
         styles = [styles]
 
     for style in styles:
         # only plain name is allowed to honor template paths
         if (not style
             or style in (pycompat.oscurdir, pycompat.ospardir)
             or pycompat.ossep in style
             or pycompat.osaltsep and pycompat.osaltsep in style):
             continue
         locations = [os.path.join(style, 'map'), 'map-' + style]
         locations.append('map')
 
         for path in paths:
             for location in locations:
                 mapfile = os.path.join(path, location)
                 if os.path.isfile(mapfile):
                     return style, mapfile
 
     raise RuntimeError("No hgweb templates found in %r" % paths)

mercurial/templateutil.py

@@ -1,584 +1,649 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
 
     Use unwrapvalue(), unwrapastype(), or unwraphybrid() to obtain the inner
     object.
     """
 
     __metaclass__ = abc.ABCMeta
 
     @abc.abstractmethod
     def itermaps(self, context):
         """Yield each template mapping"""
 
     @abc.abstractmethod
     def join(self, context, mapping, sep):
         """Join items with the separator; Returns a bytes or (possibly nested)
         generator of bytes
 
         A pre-configured template may be rendered per item if this container
         holds unprintable items.
         """
 
     @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):
         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 itermaps(self, context):
         makemap = self._makemap
         for x in self._values:
             yield makemap(x)
 
     def join(self, context, mapping, sep):
         # TODO: switch gen to (context, mapping) API?
         return joinitems((self._joinfmt(x) for x in self._values), sep)
 
     def show(self, context, mapping):
         # TODO: switch gen to (context, mapping) API?
         gen = self._gen
         if gen is None:
             return self.join(context, mapping, ' ')
         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.
     """
 
     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, context):
         yield self.tomap()
 
     def join(self, context, mapping, sep):
         # TODO: just copies the old behavior where a value was a generator
         # yielding one item, but reconsider about it. join() over a string
         # has no consistent result because a string may be a bytes, or a
         # generator yielding an item, or a generator yielding multiple items.
         # Preserving all of the current behaviors wouldn't make any sense.
         return self.show(context, mapping)
 
     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)
 
+class _mappingsequence(wrapped):
+    """Wrapper for sequence of template mappings
+
+    This represents an inner template structure (i.e. a list of dicts),
+    which can also be rendered by the specified named/literal template.
+
+    Template mappings may be nested.
+    """
+
+    def __init__(self, name=None, tmpl=None, sep=''):
+        if name is not None and tmpl is not None:
+            raise error.ProgrammingError('name and tmpl are mutually exclusive')
+        self._name = name
+        self._tmpl = tmpl
+        self._defaultsep = sep
+
+    def join(self, context, mapping, sep):
+        mapsiter = _iteroverlaymaps(context, mapping, self.itermaps(context))
+        if self._name:
+            itemiter = (context.process(self._name, m) for m in mapsiter)
+        elif self._tmpl:
+            itemiter = (context.expand(self._tmpl, m) for m in mapsiter)
+        else:
+            raise error.ParseError(_('not displayable without template'))
+        return joinitems(itemiter, sep)
+
+    def show(self, context, mapping):
+        return self.join(context, mapping, self._defaultsep)
+
+    def tovalue(self, context, mapping):
+        return list(self.itermaps(context))
+
+class mappinggenerator(_mappingsequence):
+    """Wrapper for generator of template mappings
+
+    The function ``make(context, *args)`` should return a generator of
+    mapping dicts.
+    """
+
+    def __init__(self, make, args=(), name=None, tmpl=None, sep=''):
+        super(mappinggenerator, self).__init__(name, tmpl, sep)
+        self._make = make
+        self._args = args
+
+    def itermaps(self, context):
+        return self._make(context, *self._args)
+
+class mappinglist(_mappingsequence):
+    """Wrapper for list of template mappings"""
+
+    def __init__(self, mappings, name=None, tmpl=None, sep=''):
+        super(mappinglist, self).__init__(name, tmpl, sep)
+        self._mappings = mappings
+
+    def itermaps(self, context):
+        return iter(self._mappings)
+
 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 isinstance(thing, wrapped):
         return thing
     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 _iteroverlaymaps(context, origmapping, newmappings):
+    """Generate combined mappings from the original mapping and an iterable
+    of partial mappings to override the original"""
+    for i, nm in enumerate(newmappings):
+        lm = context.overlaymap(origmapping, nm)
+        lm['index'] = i
+        yield lm
+
 def runmap(context, mapping, data):
     darg, targ = data
     d = evalrawexp(context, mapping, darg)
     if isinstance(d, wrapped):
         diter = d.itermaps(context)
     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)
 
 def joinitems(itemiter, sep):
     """Join items with the separator; Returns generator of bytes"""
     first = True
     for x in itemiter:
         if first:
             first = False
         elif sep:
             yield sep
         yield x