Re: [PATCH 2/2] data_smart.py: implement _remove as a keyword like _append.

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Wed, 2012-08-15 at 20:14 -0500, Peter Seebach wrote:
> There has historically been no way to remove a single word
> from a list, but many lists (such as DISTRO_FEATURES) are
> assembled from many sources all over the place. The _remove
> keyword offers a clean(er) way to do this.
> 
> Implementation: _remove is added to the keyword list next
> to _append and _prepend. During finalize(), the list of
> removes for a given variable is subjected to the usual
> filtering for overrides. However, the winning entries are
> not removed; they are added to a list stored in the new
> variable flag _remove_later.
> 
> At expansion time, after a variable has been expanded,
> removes for it (if any) are processed. We use the same
> _special_values magic here that we use elsewhere. Currently
> there's no caching; perhaps there should be.
> 
> Additionally, "-=" and "=-" are accepted as synonyms for
> _remove.

I read this far.

This is not going to make any friends. += and =+ behave differently to
_append with immediate vs. delayed functionality. I think equating -=
and =- is just going to confuse users even more. So no, I don't think we
can do this.

Why does this depend on 1/2 ?

Cheers,

Richard

> Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
> ---
>  lib/bb/data_smart.py                 |   45 +++++++++++++++++++++++++++++----
>  lib/bb/parse/ast.py                  |    6 ++++
>  lib/bb/parse/parse_py/ConfHandler.py |    2 +-
>  3 files changed, 46 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/bb/data_smart.py b/lib/bb/data_smart.py
> index a128914..d59f8ab 100644
> --- a/lib/bb/data_smart.py
> +++ b/lib/bb/data_smart.py
> @@ -40,8 +40,8 @@ from bb.COW  import COWDictBase
>  
>  logger = logging.getLogger("BitBake.Data")
>  
> -__setvar_keyword__ = ["_append", "_prepend"]
> -__setvar_regexp__ = re.compile('(?P<base>.*?)(?P<keyword>_append|_prepend)(_(?P<add>.*))?$')
> +__setvar_keyword__ = ["_append", "_prepend", "_remove"]
> +__setvar_regexp__ = re.compile('(?P<base>.*?)(?P<keyword>_append|_prepend|_remove)(_(?P<add>.*))?$')
>  __expand_var_regexp__ = re.compile(r"\${[^{}]+}")
>  __expand_python_regexp__ = re.compile(r"\${@.+?}")
>  
> @@ -219,7 +219,10 @@ class DataSmart(MutableMapping):
>  
>          #
>          # First we apply all overrides
> -        # Then  we will handle _append and _prepend
> +        # Then we will handle _append and _prepend and store the _remove
> +        # information for later. (_remove has to be processed during
> +        # expansion, but there's no reason to duplicate the override-checking
> +        # logic.)
>          #
>  
>          for o in overrides:
> @@ -243,12 +246,16 @@ class DataSmart(MutableMapping):
>                  except Exception, e:
>                      logger.info("Untracked delVar %s: %s" % (var, e))
>  
> -        # now on to the appends and prepends
> +        # now on to the appends and prepends, and stashing the removes
> +        # for processing during expansion
>          for op in __setvar_keyword__:
>              if op in self._special_values:
>                  appends = self._special_values[op] or []
>                  for append in appends:
>                      keep = []
> +                    # Anything we already have tagged for removal should be
> +                    # added to.
> +                    remove_later = self.getVarFlag(append, '_remove_later') or []
>                      for (a, o) in self.getVarFlag(append, op) or []:
>                          match = True
>                          if o:
> @@ -266,6 +273,19 @@ class DataSmart(MutableMapping):
>                          elif op == "_prepend":
>                              sval = a + (self.getVar(append, False) or "")
>                              self.setVar(append, sval, 'Ignore')
> +                        elif op == "_remove":
> +                            # stash for later processing
> +                            remove_later.append(a)
> +
> +                    if remove_later:
> +                        # We build a list of applicable _remove values,
> +                        # which can then be used after expansion.
> +                        self.setVarFlag(append, '_remove_later', remove_later, 'Ignore')
> +                        try:
> +                            self._special_values['_remove_later'].add(append)
> +                        except KeyError:
> +                            self._special_values['_remove_later'] = set()
> +                            self._special_values['_remove_later'].add(append)
>  
>                      # We save overrides that may be applied at some later stage
>                      # ... but we don't need to report on this.
> @@ -356,10 +376,23 @@ class DataSmart(MutableMapping):
>  
>      def getVar(self, var, expand=False, noweakdefault=False):
>          value = self.getVarFlag(var, "content", False, noweakdefault)
> +        removes = None
> +        try:
> +            # See whether any _remove values made it through overrides
> +            if var in self._special_values['_remove_later']:
> +                removes = self.getVarFlag(var, '_remove_later', True)
> +        except KeyError:
> +            pass
>  
>          # Call expand() separately to make use of the expand cache
>          if expand and value:
> -            return self.expand(value, var)
> +            value = self.expand(value, var)
> +        if removes:
> +            list = value.split(' ')
> +            for r in removes:
> +                if r in list:
> +                    list.remove(r)
> +            value = " ".join(list)
>          return value
>  
>      def renameVar(self, key, newkey, filename = None, lineno = None):
> @@ -371,7 +404,7 @@ class DataSmart(MutableMapping):
>          if val is not None:
>              self.setVar(newkey, val, filename, lineno, 'rename-create')
>  
> -        for i in ('_append', '_prepend'):
> +        for i in (__setvar_keyword__):
>              src = self.getVarFlag(key, i)
>              if src is None:
>                  continue
> diff --git a/lib/bb/parse/ast.py b/lib/bb/parse/ast.py
> index dbc2237..b2e038b 100644
> --- a/lib/bb/parse/ast.py
> +++ b/lib/bb/parse/ast.py
> @@ -113,6 +113,12 @@ class DataNode(AstNode):
>              val = "%s %s" % (groupd["value"], (self.getFunc(key, data) or ""))
>              op = 'prepend'
>              details = groupd["value"]
> +        elif (("preminus" in groupd and groupd["preminus"] != None) or
> +              ("postminus" in groupd and groupd["postminus"] != None)):
> +            # There's no correct value to set in this case; it has to
> +            # convert into a flag.
> +            key = key + "_remove"
> +            val = "%s" % groupd["value"]
>          elif "postdot" in groupd and groupd["postdot"] != None:
>              val = "%s%s" % ((self.getFunc(key, data) or ""), groupd["value"])
>              op = 'postdot'
> diff --git a/lib/bb/parse/parse_py/ConfHandler.py b/lib/bb/parse/parse_py/ConfHandler.py
> index 4a1012e..a5a25fc 100644
> --- a/lib/bb/parse/parse_py/ConfHandler.py
> +++ b/lib/bb/parse/parse_py/ConfHandler.py
> @@ -29,7 +29,7 @@ import logging
>  import bb.utils
>  from bb.parse import ParseError, resolve_file, ast, logger
>  
> -__config_regexp__  = re.compile( r"(?P<exp>export\s*)?(?P<var>[a-zA-Z0-9\-_+.${}/]+)(\[(?P<flag>[a-zA-Z0-9\-_+.]+)\])?\s*((?P<colon>:=)|(?P<lazyques>\?\?=)|(?P<ques>\?=)|(?P<append>\+=)|(?P<prepend>=\+)|(?P<predot>=\.)|(?P<postdot>\.=)|=)\s*(?P<apo>['\"])(?P<value>.*)(?P=apo)$")
> +__config_regexp__  = re.compile( r"(?P<exp>export\s*)?(?P<var>[a-zA-Z0-9\-_+.${}/]+)(\[(?P<flag>[a-zA-Z0-9\-_+.]+)\])?\s*((?P<colon>:=)|(?P<lazyques>\?\?=)|(?P<ques>\?=)|(?P<append>\+=)|(?P<prepend>=\+)|(?P<preminus>=-)|(?P<postminus>-=)|(?P<predot>=\.)|(?P<postdot>\.=)|=)\s*(?P<apo>['\"])(?P<value>.*)(?P=apo)$")
>  __include_regexp__ = re.compile( r"include\s+(.+)" )
>  __require_regexp__ = re.compile( r"require\s+(.+)" )
>  __export_regexp__ = re.compile( r"export\s+([a-zA-Z0-9\-_+.${}/]+)$" )