Source code for SCons.Subst

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"""SCons string substitution."""

import collections
import re
from inspect import signature, Parameter
from typing import Optional

import SCons.Errors
from SCons.Util import is_String, is_Sequence

# Indexed by the SUBST_* constants below.
_strconv = [
    SCons.Util.to_String_for_subst,
    SCons.Util.to_String_for_subst,
    SCons.Util.to_String_for_signature,
]

AllowableExceptions = (IndexError, NameError)


[docs] def SetAllowableExceptions(*excepts) -> None: global AllowableExceptions AllowableExceptions = [_f for _f in excepts if _f]
[docs] def raise_exception(exception, target, s): name = exception.__class__.__name__ msg = "%s `%s' trying to evaluate `%s'" % (name, exception, s) if target: raise SCons.Errors.BuildError(target[0], msg) else: raise SCons.Errors.UserError(msg)
[docs] class Literal: """A wrapper for a string. If you use this object wrapped around a string, then it will be interpreted as literal. When passed to the command interpreter, all special characters will be escaped.""" def __init__(self, lstr) -> None: self.lstr = lstr def __str__(self) -> str: return self.lstr
[docs] def escape(self, escape_func): return escape_func(self.lstr)
[docs] def for_signature(self): return self.lstr
[docs] def is_literal(self) -> bool: return True
def __eq__(self, other): if not isinstance(other, Literal): return False return self.lstr == other.lstr def __neq__(self, other) -> bool: return not self.__eq__(other) def __hash__(self): return hash(self.lstr)
[docs] class SpecialAttrWrapper: """This is a wrapper for what we call a 'Node special attribute.' This is any of the attributes of a Node that we can reference from Environment variable substitution, such as $TARGET.abspath or $SOURCES[1].filebase. We implement the same methods as Literal so we can handle special characters, plus a for_signature method, such that we can return some canonical string during signature calculation to avoid unnecessary rebuilds.""" def __init__(self, lstr, for_signature=None) -> None: """The for_signature parameter, if supplied, will be the canonical string we return from for_signature(). Else we will simply return lstr.""" self.lstr = lstr if for_signature: self.forsig = for_signature else: self.forsig = lstr def __str__(self) -> str: return self.lstr
[docs] def escape(self, escape_func): return escape_func(self.lstr)
[docs] def for_signature(self): return self.forsig
[docs] def is_literal(self) -> bool: return True
[docs] def quote_spaces(arg): """Generic function for putting double quotes around any string that has white space in it.""" if ' ' in arg or '\t' in arg: return '"%s"' % arg else: return str(arg)
[docs] class CmdStringHolder(collections.UserString): """This is a special class used to hold strings generated by scons_subst() and scons_subst_list(). It defines a special method escape(). When passed a function with an escape algorithm for a particular platform, it will return the contained string with the proper escape sequences inserted. """ def __init__(self, cmd, literal=None) -> None: super().__init__(cmd) self.literal = literal
[docs] def is_literal(self) -> bool: return self.literal
[docs] def escape(self, escape_func, quote_func=quote_spaces): """Escape the string with the supplied function. The function is expected to take an arbitrary string, then return it with all special characters escaped and ready for passing to the command interpreter. After calling this function, the next call to str() will return the escaped string. """ if self.is_literal(): return escape_func(self.data) elif ' ' in self.data or '\t' in self.data: return quote_func(self.data) else: return self.data
[docs] def escape_list(mylist, escape_func): """Escape a list of arguments by running the specified escape_func on every object in the list that has an escape() method.""" def escape(obj, escape_func=escape_func): try: e = obj.escape except AttributeError: return obj else: return e(escape_func) return list(map(escape, mylist))
[docs] class NLWrapper: """A wrapper class that delays turning a list of sources or targets into a NodeList until it's needed. The specified function supplied when the object is initialized is responsible for turning raw nodes into proxies that implement the special attributes like .abspath, .source, etc. This way, we avoid creating those proxies just "in case" someone is going to use $TARGET or the like, and only go through the trouble if we really have to. In practice, this might be a wash performance-wise, but it's a little cleaner conceptually... """ def __init__(self, list, func) -> None: self.list = list self.func = func
[docs] def _return_nodelist(self): return self.nodelist
[docs] def _gen_nodelist(self): mylist = self.list if mylist is None: mylist = [] elif not is_Sequence(mylist): mylist = [mylist] # The map(self.func) call is what actually turns # a list into appropriate proxies. self.nodelist = SCons.Util.NodeList(list(map(self.func, mylist))) self._create_nodelist = self._return_nodelist return self.nodelist
_create_nodelist = _gen_nodelist
[docs] class Targets_or_Sources(collections.UserList): """A class that implements $TARGETS or $SOURCES expansions by in turn wrapping a NLWrapper. This class handles the different methods used to access the list, calling the NLWrapper to create proxies on demand. Note that we subclass collections.UserList purely so that the is_Sequence() function will identify an object of this class as a list during variable expansion. We're not really using any collections.UserList methods in practice. """ def __init__(self, nl) -> None: self.nl = nl def __getattr__(self, attr): nl = self.nl._create_nodelist() return getattr(nl, attr) def __getitem__(self, i): nl = self.nl._create_nodelist() return nl[i] def __str__(self) -> str: nl = self.nl._create_nodelist() return str(nl) def __repr__(self) -> str: nl = self.nl._create_nodelist() return repr(nl)
[docs] class Target_or_Source: """A class that implements $TARGET or $SOURCE expansions by in turn wrapping a NLWrapper. This class handles the different methods used to access an individual proxy Node, calling the NLWrapper to create a proxy on demand. """ def __init__(self, nl) -> None: self.nl = nl def __getattr__(self, attr): nl = self.nl._create_nodelist() try: nl0 = nl[0] except IndexError: # If there is nothing in the list, then we have no attributes to # pass through, so raise AttributeError for everything. raise AttributeError("NodeList has no attribute: %s" % attr) return getattr(nl0, attr) def __str__(self) -> str: nl = self.nl._create_nodelist() if nl: return str(nl[0]) return '' def __repr__(self) -> str: nl = self.nl._create_nodelist() if nl: return repr(nl[0]) return ''
[docs] class NullNodeList(SCons.Util.NullSeq): def __call__(self, *args, **kwargs) -> str: return '' def __str__(self) -> str: return ''
NullNodesList = NullNodeList()
[docs] def subst_dict(target, source): """Create a dictionary for substitution of special construction variables. This translates the following special arguments: target - the target (object or array of objects), used to generate the TARGET and TARGETS construction variables source - the source (object or array of objects), used to generate the SOURCES and SOURCE construction variables """ dict = {} if target: def get_tgt_subst_proxy(thing): try: subst_proxy = thing.get_subst_proxy() except AttributeError: subst_proxy = thing # probably a string, just return it return subst_proxy tnl = NLWrapper(target, get_tgt_subst_proxy) dict['TARGETS'] = Targets_or_Sources(tnl) dict['TARGET'] = Target_or_Source(tnl) # This is a total cheat, but hopefully this dictionary goes # away soon anyway. We just let these expand to $TARGETS # because that's "good enough" for the use of ToolSurrogates # (see test/ToolSurrogate.py) to generate documentation. dict['CHANGED_TARGETS'] = '$TARGETS' dict['UNCHANGED_TARGETS'] = '$TARGETS' else: dict['TARGETS'] = NullNodesList dict['TARGET'] = NullNodesList if source: def get_src_subst_proxy(node): try: rfile = node.rfile except AttributeError: pass else: node = rfile() try: return node.get_subst_proxy() except AttributeError: return node # probably a String, just return it snl = NLWrapper(source, get_src_subst_proxy) dict['SOURCES'] = Targets_or_Sources(snl) dict['SOURCE'] = Target_or_Source(snl) # This is a total cheat, but hopefully this dictionary goes # away soon anyway. We just let these expand to $TARGETS # because that's "good enough" for the use of ToolSurrogates # (see test/ToolSurrogate.py) to generate documentation. dict['CHANGED_SOURCES'] = '$SOURCES' dict['UNCHANGED_SOURCES'] = '$SOURCES' else: dict['SOURCES'] = NullNodesList dict['SOURCE'] = NullNodesList return dict
_callable_args_set = {'target', 'source', 'env', 'for_signature'}
[docs] class StringSubber: """A class to construct the results of a scons_subst() call. This binds a specific construction environment, mode, target and source with two methods (substitute() and expand()) that handle the expansion. """ def __init__(self, env, mode, conv, gvars) -> None: self.env = env self.mode = mode self.conv = conv self.gvars = gvars
[docs] def expand(self, s, lvars): """Expand a single "token" as necessary, returning an appropriate string containing the expansion. This handles expanding different types of things (strings, lists, callables) appropriately. It calls the wrapper substitute() method to re-expand things as necessary, so that the results of expansions of side-by-side strings still get re-evaluated separately, not smushed together. """ if is_String(s): try: s0, s1 = s[:2] except (IndexError, ValueError): return s if s0 != '$': return s if s1 == '$': # In this case keep the double $'s which we'll later # swap for a single dollar sign as we need to retain # this information to properly avoid matching "$("" when # the actual text was "$$("" (or "$)"" when "$$)"" ) return '$$' elif s1 in '()': return s else: key = s[1:] if key[0] == '{' or '.' in key: if key[0] == '{': key = key[1:-1] # Store for error messages if we fail to expand the # value old_s = s s = None if key in lvars: s = lvars[key] elif key in self.gvars: s = self.gvars[key] else: try: s = eval(key, self.gvars, lvars) except KeyboardInterrupt: raise except Exception as e: if e.__class__ in AllowableExceptions: return '' raise_exception(e, lvars['TARGETS'], old_s) if s is None and NameError not in AllowableExceptions: raise_exception(NameError(key), lvars['TARGETS'], old_s) elif s is None: return '' # Before re-expanding the result, handle # recursive expansion by copying the local # variable dictionary and overwriting a null # string for the value of the variable name # we just expanded. # # This could potentially be optimized by only # copying lvars when s contains more expansions, # but lvars is usually supposed to be pretty # small, and deeply nested variable expansions # are probably more the exception than the norm, # so it should be tolerable for now. lv = lvars.copy() var = key.split('.')[0] lv[var] = '' return self.substitute(s, lv) elif is_Sequence(s): def func(l, conv=self.conv, substitute=self.substitute, lvars=lvars): return conv(substitute(l, lvars)) return list(map(func, s)) elif callable(s): # SCons has the unusual Null class where any __getattr__ call returns it's self, # which does not work the signature module, and the Null class returns an empty # string if called on, so we make an exception in this condition for Null class # Also allow callables where the only non default valued args match the expected defaults # this should also allow functools.partial's to work. if isinstance(s, SCons.Util.Null) or {k for k, v in signature(s).parameters.items() if k in _callable_args_set or v.default == Parameter.empty} == _callable_args_set: s = s(target=lvars['TARGETS'], source=lvars['SOURCES'], env=self.env, for_signature=(self.mode == SUBST_SIG)) else: # This probably indicates that it's a callable # object that doesn't match our calling arguments # (like an Action). if self.mode == SUBST_RAW: return s s = self.conv(s) return self.substitute(s, lvars) elif s is None: return '' else: return s
[docs] def substitute(self, args, lvars): """Substitute expansions in an argument or list of arguments. This serves as a wrapper for splitting up a string into separate tokens. """ def sub_match(match): return self.conv(self.expand(match.group(1), lvars)) if is_String(args) and not isinstance(args, CmdStringHolder): args = str(args) # In case it's a UserString. try: result = _dollar_exps.sub(sub_match, args) except TypeError: # If the internal conversion routine doesn't return # strings (it could be overridden to return Nodes, for # example), then the 1.5.2 re module will throw this # exception. Back off to a slower, general-purpose # algorithm that works for all data types. args = _separate_args.findall(args) result = [] for a in args: result.append(self.conv(self.expand(a, lvars))) if len(result) == 1: result = result[0] else: result = ''.join(map(str, result)) return result else: return self.expand(args, lvars)
[docs] class ListSubber(collections.UserList): """A class to construct the results of a scons_subst_list() call. Like StringSubber, this class binds a specific construction environment, mode, target and source with two methods (substitute() and expand()) that handle the expansion. In addition, however, this class is used to track the state of the result(s) we're gathering so we can do the appropriate thing whenever we have to append another word to the result--start a new line, start a new word, append to the current word, etc. We do this by setting the "append" attribute to the right method so that our wrapper methods only need ever call ListSubber.append(), and the rest of the object takes care of doing the right thing internally. """ def __init__(self, env, mode, conv, gvars) -> None: super().__init__([]) self.env = env self.mode = mode self.conv = conv self.gvars = gvars if self.mode == SUBST_RAW: self.add_strip = lambda x: self.append(x) else: self.add_strip = lambda x: None self.in_strip = None self.next_line()
[docs] def expanded(self, s) -> bool: """Determines if the string s requires further expansion. Due to the implementation of ListSubber expand will call itself 2 additional times for an already expanded string. This method is used to determine if a string is already fully expanded and if so exit the loop early to prevent these recursive calls. """ if not is_String(s) or isinstance(s, CmdStringHolder): return False s = str(s) # in case it's a UserString return _separate_args.findall(s) is None
[docs] def expand(self, s, lvars, within_list): """Expand a single "token" as necessary, appending the expansion to the current result. This handles expanding different types of things (strings, lists, callables) appropriately. It calls the wrapper substitute() method to re-expand things as necessary, so that the results of expansions of side-by-side strings still get re-evaluated separately, not smushed together. """ if is_String(s): try: s0, s1 = s[:2] except (IndexError, ValueError): self.append(s) return if s0 != '$': self.append(s) return if s1 == '$': self.append('$') elif s1 == '(': self.open_strip('$(') elif s1 == ')': self.close_strip('$)') else: key = s[1:] if key[0] == '{' or key.find('.') >= 0: if key[0] == '{': key = key[1:-1] # Store for error messages if we fail to expand the # value old_s = s s = None if key in lvars: s = lvars[key] elif key in self.gvars: s = self.gvars[key] else: try: s = eval(key, self.gvars, lvars) except KeyboardInterrupt: raise except Exception as e: if e.__class__ in AllowableExceptions: return raise_exception(e, lvars['TARGETS'], old_s) if s is None and NameError not in AllowableExceptions: raise_exception(NameError(), lvars['TARGETS'], old_s) elif s is None: return # If the string is already full expanded there's no # need to continue recursion. if self.expanded(s): self.append(s) return # Before re-expanding the result, handle # recursive expansion by copying the local # variable dictionary and overwriting a null # string for the value of the variable name # we just expanded. lv = lvars.copy() var = key.split('.')[0] lv[var] = '' self.substitute(s, lv, 0) self.this_word() elif is_Sequence(s): for a in s: self.substitute(a, lvars, 1) self.next_word() elif callable(s): # SCons has the unusual Null class where any __getattr__ call returns it's self, # which does not work the signature module, and the Null class returns an empty # string if called on, so we make an exception in this condition for Null class # Also allow callables where the only non default valued args match the expected defaults # this should also allow functools.partial's to work. if isinstance(s, SCons.Util.Null) or {k for k, v in signature(s).parameters.items() if k in _callable_args_set or v.default == Parameter.empty} == _callable_args_set: s = s(target=lvars['TARGETS'], source=lvars['SOURCES'], env=self.env, for_signature=(self.mode != SUBST_CMD)) else: # This probably indicates that it's a callable # object that doesn't match our calling arguments # (like an Action). if self.mode == SUBST_RAW: self.append(s) return s = self.conv(s) self.substitute(s, lvars, within_list) elif s is None: self.this_word() else: self.append(s)
[docs] def substitute(self, args, lvars, within_list) -> None: """Substitute expansions in an argument or list of arguments. This serves as a wrapper for splitting up a string into separate tokens. """ if is_String(args) and not isinstance(args, CmdStringHolder): args = str(args) # In case it's a UserString. args = _separate_args.findall(args) for a in args: if a[0] in ' \t\n\r\f\v': if '\n' in a: self.next_line() elif within_list: self.append(a) else: self.next_word() else: self.expand(a, lvars, within_list) else: self.expand(args, lvars, within_list)
[docs] def next_line(self) -> None: """Arrange for the next word to start a new line. This is like starting a new word, except that we have to append another line to the result.""" collections.UserList.append(self, []) self.next_word()
[docs] def this_word(self) -> None: """Arrange for the next word to append to the end of the current last word in the result.""" self.append = self.add_to_current_word
[docs] def next_word(self) -> None: """Arrange for the next word to start a new word.""" self.append = self.add_new_word
[docs] def add_to_current_word(self, x) -> None: """Append the string x to the end of the current last word in the result. If that is not possible, then just add it as a new word. Make sure the entire concatenated string inherits the object attributes of x (in particular, the escape function) by wrapping it as CmdStringHolder.""" if not self.in_strip or self.mode != SUBST_SIG: try: current_word = self[-1][-1] except IndexError: self.add_new_word(x) else: # All right, this is a hack and it should probably # be refactored out of existence in the future. # The issue is that we want to smoosh words together # and make one file name that gets escaped if # we're expanding something like foo$EXTENSION, # but we don't want to smoosh them together if # it's something like >$TARGET, because then we'll # treat the '>' like it's part of the file name. # So for now, just hard-code looking for the special # command-line redirection characters... try: last_char = str(current_word)[-1] except IndexError: last_char = '\0' if last_char in '<>|': self.add_new_word(x) else: y = current_word + x # We used to treat a word appended to a literal # as a literal itself, but this caused problems # with interpreting quotes around space-separated # targets on command lines. Removing this makes # none of the "substantive" end-to-end tests fail, # so we'll take this out but leave it commented # for now in case there's a problem not covered # by the test cases and we need to resurrect this. #literal1 = self.literal(self[-1][-1]) #literal2 = self.literal(x) y = self.conv(y) if is_String(y): #y = CmdStringHolder(y, literal1 or literal2) y = CmdStringHolder(y, None) self[-1][-1] = y
[docs] def add_new_word(self, x) -> None: if not self.in_strip or self.mode != SUBST_SIG: literal = self.literal(x) x = self.conv(x) if is_String(x): x = CmdStringHolder(x, literal) self[-1].append(x) self.append = self.add_to_current_word
[docs] def literal(self, x): try: l = x.is_literal except AttributeError: return None else: return l()
[docs] def open_strip(self, x) -> None: """Handle the "open strip" $( token.""" self.add_strip(x) self.in_strip = 1
[docs] def close_strip(self, x) -> None: """Handle the "close strip" $) token.""" self.add_strip(x) self.in_strip = None
# Constants for the "mode" parameter to scons_subst_list() and # scons_subst(). SUBST_RAW gives the raw command line. SUBST_CMD # gives a command line suitable for passing to a shell. SUBST_SIG # gives a command line appropriate for calculating the signature # of a command line...if this changes, we should rebuild. SUBST_CMD = 0 SUBST_RAW = 1 SUBST_SIG = 2 _rm = re.compile(r'\$[()]') # Note the pattern below only matches $( or $) when there is no # preceeding $. (Thus the (?<!\$)) _rm_split = re.compile(r'(?<!\$)(\$[()])') # Indexed by the SUBST_* constants above. _regex_remove = [ _rm, None, _rm_split ]
[docs] def _rm_list(list): return [l for l in list if l not in ('$(', '$)')]
[docs] def _remove_list(list): result = [] depth = 0 for l in list: if l == '$(': depth += 1 elif l == '$)': depth -= 1 if depth < 0: break elif depth == 0: result.append(l) if depth != 0: return None return result
# Indexed by the SUBST_* constants above. _list_remove = [ _rm_list, None, _remove_list ] # Regular expressions for splitting strings and handling substitutions, # for use by the scons_subst() and scons_subst_list() functions: # # The first expression compiled matches all of the $-introduced tokens # that we need to process in some way, and is used for substitutions. # The expressions it matches are: # # "$$" # "$(" # "$)" # "$variable" [must begin with alphabetic or underscore] # "${any stuff}" # # The second expression compiled is used for splitting strings into tokens # to be processed, and it matches all of the tokens listed above, plus # the following that affect how arguments do or don't get joined together: # # " " [white space] # "non-white-space" [without any dollar signs] # "$" [single dollar sign] # _dollar_exps_str = r'\$[\$\(\)]|\$[_a-zA-Z][\.\w]*|\${[^}]*}' _dollar_exps = re.compile(r'(%s)' % _dollar_exps_str) _separate_args = re.compile(r'(%s|\s+|[^\s$]+|\$)' % _dollar_exps_str) # This regular expression is used to replace strings of multiple white # space characters in the string result from the scons_subst() function. _space_sep = re.compile(r'[\t ]+(?![^{]*})')
[docs] def scons_subst(strSubst, env, mode=SUBST_RAW, target=None, source=None, gvars={}, lvars={}, conv=None, overrides: Optional[dict] = None): """Expand a string or list containing construction variable substitutions. This is the work-horse function for substitutions in file names and the like. The companion scons_subst_list() function (below) handles separating command lines into lists of arguments, so see that function if that's what you're looking for. """ if (isinstance(strSubst, str) and '$' not in strSubst) or isinstance(strSubst, CmdStringHolder): return strSubst if conv is None: conv = _strconv[mode] # Doing this every time is a bit of a waste, since the Executor # has typically already populated the OverrideEnvironment with # $TARGET/$SOURCE variables. We're keeping this (for now), though, # because it supports existing behavior that allows us to call # an Action directly with an arbitrary target+source pair, which # we use in Tool/tex.py to handle calling $BIBTEX when necessary. # If we dropped that behavior (or found another way to cover it), # we could get rid of this call completely and just rely on the # Executor setting the variables. if 'TARGET' not in lvars: d = subst_dict(target, source) if d: lvars = lvars.copy() lvars.update(d) # Allow last ditch chance to override lvars if overrides: lvars.update(overrides) # We're (most likely) going to eval() things. If Python doesn't # find a __builtins__ value in the global dictionary used for eval(), # it copies the current global values for you. Avoid this by # setting it explicitly and then deleting, so we don't pollute the # construction environment Dictionary(ies) that are typically used # for expansion. gvars['__builtins__'] = __builtins__ ss = StringSubber(env, mode, conv, gvars) result = ss.substitute(strSubst, lvars) try: del gvars['__builtins__'] except KeyError: pass res = result if is_String(result): # Remove $(-$) pairs and any stuff in between, # if that's appropriate. remove = _regex_remove[mode] if remove: if mode == SUBST_SIG: result = _list_remove[mode](remove.split(result)) if result is None: raise SCons.Errors.UserError("Unbalanced $(/$) in: " + res) result = ' '.join(result) else: result = remove.sub('', result) if mode != SUBST_RAW: # Compress strings of white space characters into # a single space. result = _space_sep.sub(' ', result).strip() # Now replace escaped $'s currently "$$" # This is needed because we now retain $$ instead of # replacing them during substition to avoid # improperly trying to escape "$$(" as being "$(" result = result.replace('$$','$') elif is_Sequence(result): remove = _list_remove[mode] if remove: result = remove(result) if result is None: raise SCons.Errors.UserError("Unbalanced $(/$) in: " + str(res)) return result
[docs] def scons_subst_list(strSubst, env, mode=SUBST_RAW, target=None, source=None, gvars={}, lvars={}, conv=None, overrides: Optional[dict] = None): """Substitute construction variables in a string (or list or other object) and separate the arguments into a command list. The companion scons_subst() function (above) handles basic substitutions within strings, so see that function instead if that's what you're looking for. """ if conv is None: conv = _strconv[mode] # Doing this every time is a bit of a waste, since the Executor # has typically already populated the OverrideEnvironment with # $TARGET/$SOURCE variables. We're keeping this (for now), though, # because it supports existing behavior that allows us to call # an Action directly with an arbitrary target+source pair, which # we use in Tool/tex.py to handle calling $BIBTEX when necessary. # If we dropped that behavior (or found another way to cover it), # we could get rid of this call completely and just rely on the # Executor setting the variables. if 'TARGET' not in lvars: d = subst_dict(target, source) if d: lvars = lvars.copy() lvars.update(d) # Allow caller to specify last ditch override of lvars if overrides: lvars.update(overrides) # We're (most likely) going to eval() things. If Python doesn't # find a __builtins__ value in the global dictionary used for eval(), # it copies the current global values for you. Avoid this by # setting it explicitly and then deleting, so we don't pollute the # construction environment Dictionary(ies) that are typically used # for expansion. gvars['__builtins__'] = __builtins__ ls = ListSubber(env, mode, conv, gvars) ls.substitute(strSubst, lvars, 0) try: del gvars['__builtins__'] except KeyError: pass return ls.data
[docs] def scons_subst_once(strSubst, env, key): """Perform single (non-recursive) substitution of a single construction variable keyword. This is used when setting a variable when copying or overriding values in an Environment. We want to capture (expand) the old value before we override it, so people can do things like: env2 = env.Clone(CCFLAGS = '$CCFLAGS -g') We do this with some straightforward, brute-force code here... """ if isinstance(strSubst, str) and strSubst.find('$') < 0: return strSubst matchlist = ['$' + key, '${' + key + '}'] val = env.get(key, '') def sub_match(match, val=val, matchlist=matchlist): a = match.group(1) if a in matchlist: a = val if is_Sequence(a): return ' '.join(map(str, a)) else: return str(a) if is_Sequence(strSubst): result = [] for arg in strSubst: if is_String(arg): if arg in matchlist: arg = val if is_Sequence(arg): result.extend(arg) else: result.append(arg) else: result.append(_dollar_exps.sub(sub_match, arg)) else: result.append(arg) return result elif is_String(strSubst): return _dollar_exps.sub(sub_match, strSubst) else: return strSubst
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