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authorKenneth Heafield <github@kheafield.com>2012-05-12 14:01:52 -0400
committerKenneth Heafield <github@kheafield.com>2012-05-12 14:01:52 -0400
commit3faecf9a00512dcbc8712c4bca9adae72fb64410 (patch)
tree9761b50d12f81a675fb7cbc663ceebad15079f78 /jam-files/boost-build/build/generators.jam
parentc806a8fff63043f63773874986301f2822a2b552 (diff)
Give in and copy bjam into cdec source code
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+# Copyright Vladimir Prus 2002.
+# Copyright Rene Rivera 2006.
+#
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at
+# http://www.boost.org/LICENSE_1_0.txt)
+
+# Manages 'generators' --- objects which can do transformation between different
+# target types and contain algorithm for finding transformation from sources to
+# targets.
+#
+# The main entry point to this module is generators.construct rule. It is given
+# a list of source targets, desired target type and a set of properties. It
+# starts by selecting 'viable generators', which have any chances of producing
+# the desired target type with the required properties. Generators are ranked
+# and a set of the most specific ones is selected.
+#
+# The most specific generators have their 'run' methods called, with the
+# properties and list of sources. Each one selects a target which can be
+# directly consumed, and tries to convert the remaining ones to the types it can
+# consume. This is done by recursively calling 'construct' with all consumable
+# types.
+#
+# If the generator has collected all the targets it needs, it creates targets
+# corresponding to result, and returns it. When all generators have been run,
+# results of one of them are selected and returned as a result.
+#
+# It is quite possible for 'construct' to return more targets that it was asked
+# for. For example, if it were asked to generate a target of type EXE, but the
+# only found generator produces both EXE and TDS (file with debug) information.
+# The extra target will be returned.
+#
+# Likewise, when generator tries to convert sources to consumable types, it can
+# get more targets that it was asked for. The question is what to do with extra
+# targets. Boost.Build attempts to convert them to requested types, and attempts
+# that as early as possible. Specifically, this is done after invoking each
+# generator. TODO: An example is needed to document the rationale for trying
+# extra target conversion at that point.
+#
+# In order for the system to be able to use a specific generator instance 'when
+# needed', the instance needs to be registered with the system using
+# generators.register() or one of its related rules. Unregistered generators may
+# only be run explicitly and will not be considered by Boost.Build when when
+# converting between given target types.
+
+import "class" : new ;
+import errors ;
+import property-set ;
+import sequence ;
+import set ;
+import type ;
+import utility ;
+import virtual-target ;
+
+
+if "--debug-generators" in [ modules.peek : ARGV ]
+{
+ .debug = true ;
+}
+
+
+# Updated cached viable source target type information as needed after a new
+# target type gets defined. This is needed because if a target type is a viable
+# source target type for some generator then all of the target type's derived
+# target types should automatically be considered as viable source target types
+# for the same generator as well. Does nothing if a non-derived target type is
+# passed to it.
+#
+rule update-cached-information-with-a-new-type ( type )
+{
+ local base-type = [ type.base $(type) ] ;
+ if $(base-type)
+ {
+ for local g in $(.vstg-cached-generators)
+ {
+ if $(base-type) in $(.vstg.$(g))
+ {
+ .vstg.$(g) += $(type) ;
+ }
+ }
+
+ for local t in $(.vst-cached-types)
+ {
+ if $(base-type) in $(.vst.$(t))
+ {
+ .vst.$(t) += $(type) ;
+ }
+ }
+ }
+}
+
+
+# Clears cached viable source target type information except for target types
+# and generators with all source types listed as viable. Should be called when
+# something invalidates those cached values by possibly causing some new source
+# types to become viable.
+#
+local rule invalidate-extendable-viable-source-target-type-cache ( )
+{
+ local generators-with-cached-source-types = $(.vstg-cached-generators) ;
+ .vstg-cached-generators = ;
+ for local g in $(generators-with-cached-source-types)
+ {
+ if $(.vstg.$(g)) = *
+ {
+ .vstg-cached-generators += $(g) ;
+ }
+ else
+ {
+ .vstg.$(g) = ;
+ }
+ }
+
+ local types-with-cached-source-types = $(.vst-cached-types) ;
+ .vst-cached-types = ;
+ for local t in $(types-with-cached-source-types)
+ {
+ if $(.vst.$(t)) = *
+ {
+ .vst-cached-types += $(t) ;
+ }
+ else
+ {
+ .vst.$(t) = ;
+ }
+ }
+}
+
+
+# Outputs a debug message if generators debugging is on. Each element of
+# 'message' is checked to see if it is a class instance. If so, instead of the
+# value, the result of 'str' call is output.
+#
+local rule generators.dout ( message * )
+{
+ if $(.debug)
+ {
+ ECHO [ sequence.transform utility.str : $(message) ] ;
+ }
+}
+
+
+local rule indent ( )
+{
+ return $(.indent:J="") ;
+}
+
+
+local rule increase-indent ( )
+{
+ .indent += " " ;
+}
+
+
+local rule decrease-indent ( )
+{
+ .indent = $(.indent[2-]) ;
+}
+
+
+# Models a generator.
+#
+class generator
+{
+ import generators : indent increase-indent decrease-indent generators.dout ;
+ import set ;
+ import utility ;
+ import feature ;
+ import errors ;
+ import sequence ;
+ import type ;
+ import virtual-target ;
+ import "class" : new ;
+ import property ;
+ import path ;
+
+ EXPORT class@generator : indent increase-indent decrease-indent
+ generators.dout ;
+
+ rule __init__ (
+ id # Identifies the generator - should be name
+ # of the rule which sets up the build
+ # actions.
+
+ composing ? # Whether generator processes each source
+ # target in turn, converting it to required
+ # types. Ordinary generators pass all
+ # sources together to the recursive
+ # generators.construct-types call.
+
+ : source-types * # Types that this generator can handle. If
+ # empty, the generator can consume anything.
+
+ : target-types-and-names + # Types the generator will create and,
+ # optionally, names for created targets.
+ # Each element should have the form
+ # type["(" name-pattern ")"], for example,
+ # obj(%_x). Generated target name will be
+ # found by replacing % with the name of
+ # source, provided an explicit name was not
+ # specified.
+
+ : requirements *
+ )
+ {
+ self.id = $(id) ;
+ self.rule-name = $(id) ;
+ self.composing = $(composing) ;
+ self.source-types = $(source-types) ;
+ self.target-types-and-names = $(target-types-and-names) ;
+ self.requirements = $(requirements) ;
+
+ for local e in $(target-types-and-names)
+ {
+ # Create three parallel lists: one with the list of target types,
+ # and two other with prefixes and postfixes to be added to target
+ # name. We use parallel lists for prefix and postfix (as opposed to
+ # mapping), because given target type might occur several times, for
+ # example "H H(%_symbols)".
+ local m = [ MATCH ([^\\(]*)(\\((.*)%(.*)\\))? : $(e) ] ;
+ self.target-types += $(m[1]) ;
+ self.name-prefix += $(m[3]:E="") ;
+ self.name-postfix += $(m[4]:E="") ;
+ }
+
+ # Note that 'transform' here, is the same as 'for_each'.
+ sequence.transform type.validate : $(self.source-types) ;
+ sequence.transform type.validate : $(self.target-types) ;
+ }
+
+ ################# End of constructor #################
+
+ rule id ( )
+ {
+ return $(self.id) ;
+ }
+
+ # Returns the list of target type the generator accepts.
+ #
+ rule source-types ( )
+ {
+ return $(self.source-types) ;
+ }
+
+ # Returns the list of target types that this generator produces. It is
+ # assumed to be always the same -- i.e. it can not change depending on some
+ # provided list of sources.
+ #
+ rule target-types ( )
+ {
+ return $(self.target-types) ;
+ }
+
+ # Returns the required properties for this generator. Properties in returned
+ # set must be present in build properties if this generator is to be used.
+ # If result has grist-only element, that build properties must include some
+ # value of that feature.
+ #
+ # XXX: remove this method?
+ #
+ rule requirements ( )
+ {
+ return $(self.requirements) ;
+ }
+
+ rule set-rule-name ( rule-name )
+ {
+ self.rule-name = $(rule-name) ;
+ }
+
+ rule rule-name ( )
+ {
+ return $(self.rule-name) ;
+ }
+
+ # Returns a true value if the generator can be run with the specified
+ # properties.
+ #
+ rule match-rank ( property-set-to-match )
+ {
+ # See if generator requirements are satisfied by 'properties'. Treat a
+ # feature name in requirements (i.e. grist-only element), as matching
+ # any value of the feature.
+ local all-requirements = [ requirements ] ;
+
+ local property-requirements feature-requirements ;
+ for local r in $(all-requirements)
+ {
+ if $(r:G=)
+ {
+ property-requirements += $(r) ;
+ }
+ else
+ {
+ feature-requirements += $(r) ;
+ }
+ }
+
+ local properties-to-match = [ $(property-set-to-match).raw ] ;
+ if $(property-requirements) in $(properties-to-match) &&
+ $(feature-requirements) in $(properties-to-match:G)
+ {
+ return true ;
+ }
+ else
+ {
+ return ;
+ }
+ }
+
+ # Returns another generator which differs from $(self) in
+ # - id
+ # - value to <toolset> feature in properties
+ #
+ rule clone ( new-id : new-toolset-properties + )
+ {
+ local g = [ new $(__class__) $(new-id) $(self.composing) :
+ $(self.source-types) : $(self.target-types-and-names) :
+ # Note: this does not remove any subfeatures of <toolset> which
+ # might cause problems.
+ [ property.change $(self.requirements) : <toolset> ]
+ $(new-toolset-properties) ] ;
+ return $(g) ;
+ }
+
+ # Creates another generator that is the same as $(self), except that if
+ # 'base' is in target types of $(self), 'type' will in target types of the
+ # new generator.
+ #
+ rule clone-and-change-target-type ( base : type )
+ {
+ local target-types ;
+ for local t in $(self.target-types-and-names)
+ {
+ local m = [ MATCH ([^\\(]*)(\\(.*\\))? : $(t) ] ;
+ if $(m) = $(base)
+ {
+ target-types += $(type)$(m[2]:E="") ;
+ }
+ else
+ {
+ target-types += $(t) ;
+ }
+ }
+
+ local g = [ new $(__class__) $(self.id) $(self.composing) :
+ $(self.source-types) : $(target-types) : $(self.requirements) ] ;
+ if $(self.rule-name)
+ {
+ $(g).set-rule-name $(self.rule-name) ;
+ }
+ return $(g) ;
+ }
+
+ # Tries to invoke this generator on the given sources. Returns a list of
+ # generated targets (instances of 'virtual-target') and optionally a set of
+ # properties to be added to the usage-requirements for all the generated
+ # targets. Returning nothing from run indicates that the generator was
+ # unable to create the target.
+ #
+ rule run
+ (
+ project # Project for which the targets are generated.
+ name ? # Used when determining the 'name' attribute for all
+ # generated targets. See the 'generated-targets' method.
+ : property-set # Desired properties for generated targets.
+ : sources + # Source targets.
+ )
+ {
+ generators.dout [ indent ] " ** generator" $(self.id) ;
+ generators.dout [ indent ] " composing:" $(self.composing) ;
+
+ if ! $(self.composing) && $(sources[2]) && $(self.source-types[2])
+ {
+ errors.error "Unsupported source/source-type combination" ;
+ }
+
+ # We do not run composing generators if no name is specified. The reason
+ # is that composing generator combines several targets, which can have
+ # different names, and it cannot decide which name to give for produced
+ # target. Therefore, the name must be passed.
+ #
+ # This in effect, means that composing generators are runnable only at
+ # the top-level of a transformation graph, or if their name is passed
+ # explicitly. Thus, we dissallow composing generators in the middle. For
+ # example, the transformation CPP -> OBJ -> STATIC_LIB -> RSP -> EXE
+ # will not be allowed as the OBJ -> STATIC_LIB generator is composing.
+ if ! $(self.composing) || $(name)
+ {
+ run-really $(project) $(name) : $(property-set) : $(sources) ;
+ }
+ }
+
+ rule run-really ( project name ? : property-set : sources + )
+ {
+ # Targets that this generator will consume directly.
+ local consumed = ;
+ # Targets that can not be consumed and will be returned as-is.
+ local bypassed = ;
+
+ if $(self.composing)
+ {
+ convert-multiple-sources-to-consumable-types $(project)
+ : $(property-set) : $(sources) : consumed bypassed ;
+ }
+ else
+ {
+ convert-to-consumable-types $(project) $(name) : $(property-set)
+ : $(sources) : : consumed bypassed ;
+ }
+
+ local result ;
+ if $(consumed)
+ {
+ result = [ construct-result $(consumed) : $(project) $(name) :
+ $(property-set) ] ;
+ }
+
+ if $(result)
+ {
+ generators.dout [ indent ] " SUCCESS: " $(result) ;
+ }
+ else
+ {
+ generators.dout [ indent ] " FAILURE" ;
+ }
+ generators.dout ;
+ return $(result) ;
+ }
+
+ # Constructs the dependency graph to be returned by this generator.
+ #
+ rule construct-result
+ (
+ consumed + # Already prepared list of consumable targets.
+ # Composing generators may receive multiple sources
+ # all of which will have types matching those in
+ # $(self.source-types). Non-composing generators with
+ # multiple $(self.source-types) will receive exactly
+ # len $(self.source-types) sources with types matching
+ # those in $(self.source-types). And non-composing
+ # generators with only a single source type may
+ # receive multiple sources with all of them of the
+ # type listed in $(self.source-types).
+ : project name ?
+ : property-set # Properties to be used for all actions created here.
+ )
+ {
+ local result ;
+ # If this is 1->1 transformation, apply it to all consumed targets in
+ # order.
+ if ! $(self.source-types[2]) && ! $(self.composing)
+ {
+ for local r in $(consumed)
+ {
+ result += [ generated-targets $(r) : $(property-set) :
+ $(project) $(name) ] ;
+ }
+ }
+ else if $(consumed)
+ {
+ result += [ generated-targets $(consumed) : $(property-set) :
+ $(project) $(name) ] ;
+ }
+ return $(result) ;
+ }
+
+ # Determine target name from fullname (maybe including path components)
+ # Place optional prefix and postfix around basename
+ #
+ rule determine-target-name ( fullname : prefix ? : postfix ? )
+ {
+ # See if we need to add directory to the target name.
+ local dir = $(fullname:D) ;
+ local name = $(fullname:B) ;
+
+ name = $(prefix:E=)$(name) ;
+ name = $(name)$(postfix:E=) ;
+
+ if $(dir) &&
+ # Never append '..' to target path.
+ ! [ MATCH .*(\\.\\.).* : $(dir) ]
+ &&
+ ! [ path.is-rooted $(dir) ]
+ {
+ # Relative path is always relative to the source
+ # directory. Retain it, so that users can have files
+ # with the same in two different subdirectories.
+ name = $(dir)/$(name) ;
+ }
+ return $(name) ;
+ }
+
+ # Determine the name of the produced target from the names of the sources.
+ #
+ rule determine-output-name ( sources + )
+ {
+ # The simple case if when a name of source has single dot. Then, we take
+ # the part before dot. Several dots can be caused by:
+ # - using source file like a.host.cpp, or
+ # - a type whose suffix has a dot. Say, we can type 'host_cpp' with
+ # extension 'host.cpp'.
+ # In the first case, we want to take the part up to the last dot. In the
+ # second case -- not sure, but for now take the part up to the last dot
+ # too.
+ name = [ utility.basename [ $(sources[1]).name ] ] ;
+
+ for local s in $(sources[2])
+ {
+ local n2 = [ utility.basename [ $(s).name ] ] ;
+ if $(n2) != $(name)
+ {
+ errors.error "$(self.id): source targets have different names: cannot determine target name" ;
+ }
+ }
+ name = [ determine-target-name [ $(sources[1]).name ] ] ;
+ return $(name) ;
+ }
+
+ # Constructs targets that are created after consuming 'sources'. The result
+ # will be the list of virtual-target, which has the same length as the
+ # 'target-types' attribute and with corresponding types.
+ #
+ # When 'name' is empty, all source targets must have the same 'name'
+ # attribute value, which will be used instead of the 'name' argument.
+ #
+ # The 'name' attribute value for each generated target will be equal to
+ # the 'name' parameter if there is no name pattern for this type. Otherwise,
+ # the '%' symbol in the name pattern will be replaced with the 'name'
+ # parameter to obtain the 'name' attribute.
+ #
+ # For example, if targets types are T1 and T2 (with name pattern "%_x"),
+ # suffixes for T1 and T2 are .t1 and .t2, and source is foo.z, then created
+ # files would be "foo.t1" and "foo_x.t2". The 'name' attribute actually
+ # determines the basename of a file.
+ #
+ # Note that this pattern mechanism has nothing to do with implicit patterns
+ # in make. It is a way to produce a target whose name is different than the
+ # name of its source.
+ #
+ rule generated-targets ( sources + : property-set : project name ? )
+ {
+ if ! $(name)
+ {
+ name = [ determine-output-name $(sources) ] ;
+ }
+
+ # Assign an action for each target.
+ local action = [ action-class ] ;
+ local a = [ class.new $(action) $(sources) : $(self.rule-name) :
+ $(property-set) ] ;
+
+ # Create generated target for each target type.
+ local targets ;
+ local pre = $(self.name-prefix) ;
+ local post = $(self.name-postfix) ;
+ for local t in $(self.target-types)
+ {
+ local generated-name = $(pre[1])$(name:BS)$(post[1]) ;
+ generated-name = $(generated-name:R=$(name:D)) ;
+ pre = $(pre[2-]) ;
+ post = $(post[2-]) ;
+
+ targets += [ class.new file-target $(generated-name) : $(t) :
+ $(project) : $(a) ] ;
+ }
+
+ return [ sequence.transform virtual-target.register : $(targets) ] ;
+ }
+
+ # Attempts to convert 'sources' to targets of types that this generator can
+ # handle. The intention is to produce the set of targets that can be used
+ # when the generator is run.
+ #
+ rule convert-to-consumable-types
+ (
+ project name ?
+ : property-set
+ : sources +
+ : only-one ? # Convert 'source' to only one of the source types. If
+ # there is more that one possibility, report an error.
+ : consumed-var # Name of the variable which receives all targets which
+ # can be consumed.
+ bypassed-var # Name of the variable which receives all targets which
+ # can not be consumed.
+ )
+ {
+ # We are likely to be passed 'consumed' and 'bypassed' var names. Use
+ # '_' to avoid name conflicts.
+ local _consumed ;
+ local _bypassed ;
+ local missing-types ;
+
+ if $(sources[2])
+ {
+ # Do not know how to handle several sources yet. Just try to pass
+ # the request to other generator.
+ missing-types = $(self.source-types) ;
+ }
+ else
+ {
+ consume-directly $(sources) : _consumed : missing-types ;
+ }
+
+ # No need to search for transformation if some source type has consumed
+ # source and no more source types are needed.
+ if $(only-one) && $(_consumed)
+ {
+ missing-types = ;
+ }
+
+ # TODO: we should check that only one source type if create of
+ # 'only-one' is true.
+ # TODO: consider if consumed/bypassed separation should be done by
+ # 'construct-types'.
+
+ if $(missing-types)
+ {
+ local transformed = [ generators.construct-types $(project) $(name)
+ : $(missing-types) : $(property-set) : $(sources) ] ;
+
+ # Add targets of right type to 'consumed'. Add others to 'bypassed'.
+ # The 'generators.construct' rule has done its best to convert
+ # everything to the required type. There is no need to rerun it on
+ # targets of different types.
+
+ # NOTE: ignoring usage requirements.
+ for local t in $(transformed[2-])
+ {
+ if [ $(t).type ] in $(missing-types)
+ {
+ _consumed += $(t) ;
+ }
+ else
+ {
+ _bypassed += $(t) ;
+ }
+ }
+ }
+
+ _consumed = [ sequence.unique $(_consumed) ] ;
+ _bypassed = [ sequence.unique $(_bypassed) ] ;
+
+ # Remove elements of '_bypassed' that are in '_consumed'.
+
+ # Suppose the target type of current generator, X is produced from X_1
+ # and X_2, which are produced from Y by one generator. When creating X_1
+ # from Y, X_2 will be added to 'bypassed'. Likewise, when creating X_2
+ # from Y, X_1 will be added to 'bypassed', but they are also in
+ # 'consumed'. We have to remove them from bypassed, so that generators
+ # up the call stack do not try to convert them.
+
+ # In this particular case, X_1 instance in 'consumed' and X_1 instance
+ # in 'bypassed' will be the same: because they have the same source and
+ # action name, and 'virtual-target.register' will not allow two
+ # different instances. Therefore, it is OK to use 'set.difference'.
+
+ _bypassed = [ set.difference $(_bypassed) : $(_consumed) ] ;
+
+ $(consumed-var) += $(_consumed) ;
+ $(bypassed-var) += $(_bypassed) ;
+ }
+
+ # Converts several files to consumable types. Called for composing
+ # generators only.
+ #
+ rule convert-multiple-sources-to-consumable-types ( project : property-set :
+ sources * : consumed-var bypassed-var )
+ {
+ # We process each source one-by-one, trying to convert it to a usable
+ # type.
+ for local source in $(sources)
+ {
+ local _c ;
+ local _b ;
+ # TODO: need to check for failure on each source.
+ convert-to-consumable-types $(project) : $(property-set) : $(source)
+ : true : _c _b ;
+ if ! $(_c)
+ {
+ generators.dout [ indent ] " failed to convert " $(source) ;
+ }
+ $(consumed-var) += $(_c) ;
+ $(bypassed-var) += $(_b) ;
+ }
+ }
+
+ rule consume-directly ( source : consumed-var : missing-types-var )
+ {
+ local real-source-type = [ $(source).type ] ;
+
+ # If there are no source types, we can consume anything.
+ local source-types = $(self.source-types) ;
+ source-types ?= $(real-source-type) ;
+
+ for local st in $(source-types)
+ {
+ # The 'source' if of the right type already.
+ if $(real-source-type) = $(st) || [ type.is-derived
+ $(real-source-type) $(st) ]
+ {
+ $(consumed-var) += $(source) ;
+ }
+ else
+ {
+ $(missing-types-var) += $(st) ;
+ }
+ }
+ }
+
+ # Returns the class to be used to actions. Default implementation returns
+ # "action".
+ #
+ rule action-class ( )
+ {
+ return "action" ;
+ }
+}
+
+
+# Registers a new generator instance 'g'.
+#
+rule register ( g )
+{
+ .all-generators += $(g) ;
+
+ # A generator can produce several targets of the same type. We want unique
+ # occurrence of that generator in .generators.$(t) in that case, otherwise,
+ # it will be tried twice and we will get a false ambiguity.
+ for local t in [ sequence.unique [ $(g).target-types ] ]
+ {
+ .generators.$(t) += $(g) ;
+ }
+
+ # Update the set of generators for toolset.
+
+ # TODO: should we check that generator with this id is not already
+ # registered. For example, the fop.jam module intentionally declared two
+ # generators with the same id, so such check will break it.
+ local id = [ $(g).id ] ;
+
+ # Some generators have multiple periods in their name, so a simple $(id:S=)
+ # will not generate the right toolset name. E.g. if id = gcc.compile.c++,
+ # then .generators-for-toolset.$(id:S=) will append to
+ # .generators-for-toolset.gcc.compile, which is a separate value from
+ # .generators-for-toolset.gcc. Correcting this makes generator inheritance
+ # work properly. See also inherit-generators in the toolset module.
+ local base = $(id) ;
+ while $(base:S)
+ {
+ base = $(base:B) ;
+ }
+ .generators-for-toolset.$(base) += $(g) ;
+
+
+ # After adding a new generator that can construct new target types, we need
+ # to clear the related cached viable source target type information for
+ # constructing a specific target type or using a specific generator. Cached
+ # viable source target type lists affected by this are those containing any
+ # of the target types constructed by the new generator or any of their base
+ # target types.
+ #
+ # A more advanced alternative to clearing that cached viable source target
+ # type information would be to expand it with additional source types or
+ # even better - mark it as needing to be expanded on next use.
+ #
+ # Also see the http://thread.gmane.org/gmane.comp.lib.boost.build/19077
+ # mailing list thread for an even more advanced idea of how we could convert
+ # Boost Build's Jamfile processing, target selection and generator selection
+ # into separate steps which would prevent these caches from ever being
+ # invalidated.
+ #
+ # For now we just clear all the cached viable source target type information
+ # that does not simply state 'all types' and may implement a more detailed
+ # algorithm later on if it becomes needed.
+
+ invalidate-extendable-viable-source-target-type-cache ;
+}
+
+
+# Creates a new non-composing 'generator' class instance and registers it.
+# Returns the created instance. Rationale: the instance is returned so that it
+# is possible to first register a generator and then call its 'run' method,
+# bypassing the whole generator selection process.
+#
+rule register-standard ( id : source-types * : target-types + : requirements * )
+{
+ local g = [ new generator $(id) : $(source-types) : $(target-types) :
+ $(requirements) ] ;
+ register $(g) ;
+ return $(g) ;
+}
+
+
+# Creates a new composing 'generator' class instance and registers it.
+#
+rule register-composing ( id : source-types * : target-types + : requirements *
+ )
+{
+ local g = [ new generator $(id) true : $(source-types) : $(target-types) :
+ $(requirements) ] ;
+ register $(g) ;
+ return $(g) ;
+}
+
+
+# Returns all generators belonging to the given 'toolset', i.e. whose ids are
+# '$(toolset).<something>'.
+#
+rule generators-for-toolset ( toolset )
+{
+ return $(.generators-for-toolset.$(toolset)) ;
+}
+
+
+# Make generator 'overrider-id' be preferred to 'overridee-id'. If, when
+# searching for generators that could produce a target of a certain type, both
+# those generators are among viable generators, the overridden generator is
+# immediately discarded.
+#
+# The overridden generators are discarded immediately after computing the list
+# of viable generators but before running any of them.
+#
+rule override ( overrider-id : overridee-id )
+{
+ .override.$(overrider-id) += $(overridee-id) ;
+}
+
+
+# Returns a list of source type which can possibly be converted to 'target-type'
+# by some chain of generator invocation.
+#
+# More formally, takes all generators for 'target-type' and returns a union of
+# source types for those generators and result of calling itself recursively on
+# source types.
+#
+# Returns '*' in case any type should be considered a viable source type for the
+# given type.
+#
+local rule viable-source-types-real ( target-type )
+{
+ local result ;
+
+ # 't0' is the initial list of target types we need to process to get a list
+ # of their viable source target types. New target types will not be added to
+ # this list.
+ local t0 = [ type.all-bases $(target-type) ] ;
+
+ # 't' is the list of target types which have not yet been processed to get a
+ # list of their viable source target types. This list will get expanded as
+ # we locate more target types to process.
+ local t = $(t0) ;
+
+ while $(t)
+ {
+ # Find all generators for the current type. Unlike
+ # 'find-viable-generators' we do not care about the property-set.
+ local generators = $(.generators.$(t[1])) ;
+ t = $(t[2-]) ;
+
+ while $(generators)
+ {
+ local g = $(generators[1]) ;
+ generators = $(generators[2-]) ;
+
+ if ! [ $(g).source-types ]
+ {
+ # Empty source types -- everything can be accepted.
+ result = * ;
+ # This will terminate this loop.
+ generators = ;
+ # This will terminate the outer loop.
+ t = ;
+ }
+
+ for local source-type in [ $(g).source-types ]
+ {
+ if ! $(source-type) in $(result)
+ {
+ # If a generator accepts a 'source-type' it will also
+ # happily accept any type derived from it.
+ for local n in [ type.all-derived $(source-type) ]
+ {
+ if ! $(n) in $(result)
+ {
+ # Here there is no point in adding target types to
+ # the list of types to process in case they are or
+ # have already been on that list. We optimize this
+ # check by realizing that we only need to avoid the
+ # original target type's base types. Other target
+ # types that are or have been on the list of target
+ # types to process have been added to the 'result'
+ # list as well and have thus already been eliminated
+ # by the previous if.
+ if ! $(n) in $(t0)
+ {
+ t += $(n) ;
+ }
+ result += $(n) ;
+ }
+ }
+ }
+ }
+ }
+ }
+
+ return $(result) ;
+}
+
+
+# Helper rule, caches the result of 'viable-source-types-real'.
+#
+rule viable-source-types ( target-type )
+{
+ local key = .vst.$(target-type) ;
+ if ! $($(key))
+ {
+ .vst-cached-types += $(target-type) ;
+ local v = [ viable-source-types-real $(target-type) ] ;
+ if ! $(v)
+ {
+ v = none ;
+ }
+ $(key) = $(v) ;
+ }
+
+ if $($(key)) != none
+ {
+ return $($(key)) ;
+ }
+}
+
+
+# Returns the list of source types, which, when passed to 'run' method of
+# 'generator', has some change of being eventually used (probably after
+# conversion by other generators).
+#
+# Returns '*' in case any type should be considered a viable source type for the
+# given generator.
+#
+rule viable-source-types-for-generator-real ( generator )
+{
+ local source-types = [ $(generator).source-types ] ;
+ if ! $(source-types)
+ {
+ # If generator does not specify any source types, it might be a special
+ # generator like builtin.lib-generator which just relays to other
+ # generators. Return '*' to indicate that any source type is possibly
+ # OK, since we do not know for sure.
+ return * ;
+ }
+ else
+ {
+ local result ;
+ while $(source-types)
+ {
+ local s = $(source-types[1]) ;
+ source-types = $(source-types[2-]) ;
+ local viable-sources = [ generators.viable-source-types $(s) ] ;
+ if $(viable-sources) = *
+ {
+ result = * ;
+ source-types = ; # Terminate the loop.
+ }
+ else
+ {
+ result += [ type.all-derived $(s) ] $(viable-sources) ;
+ }
+ }
+ return [ sequence.unique $(result) ] ;
+ }
+}
+
+
+# Helper rule, caches the result of 'viable-source-types-for-generator'.
+#
+local rule viable-source-types-for-generator ( generator )
+{
+ local key = .vstg.$(generator) ;
+ if ! $($(key))
+ {
+ .vstg-cached-generators += $(generator) ;
+ local v = [ viable-source-types-for-generator-real $(generator) ] ;
+ if ! $(v)
+ {
+ v = none ;
+ }
+ $(key) = $(v) ;
+ }
+
+ if $($(key)) != none
+ {
+ return $($(key)) ;
+ }
+}
+
+
+# Returns usage requirements + list of created targets.
+#
+local rule try-one-generator-really ( project name ? : generator : target-type
+ : property-set : sources * )
+{
+ local targets =
+ [ $(generator).run $(project) $(name) : $(property-set) : $(sources) ] ;
+
+ local usage-requirements ;
+ local success ;
+
+ generators.dout [ indent ] returned $(targets) ;
+
+ if $(targets)
+ {
+ success = true ;
+
+ if [ class.is-a $(targets[1]) : property-set ]
+ {
+ usage-requirements = $(targets[1]) ;
+ targets = $(targets[2-]) ;
+ }
+ else
+ {
+ usage-requirements = [ property-set.empty ] ;
+ }
+ }
+
+ generators.dout [ indent ] " generator" [ $(generator).id ] " spawned " ;
+ generators.dout [ indent ] " " $(targets) ;
+ if $(usage-requirements)
+ {
+ generators.dout [ indent ] " with usage requirements:" $(x) ;
+ }
+
+ if $(success)
+ {
+ return $(usage-requirements) $(targets) ;
+ }
+}
+
+
+# Checks if generator invocation can be pruned, because it is guaranteed to
+# fail. If so, quickly returns an empty list. Otherwise, calls
+# try-one-generator-really.
+#
+local rule try-one-generator ( project name ? : generator : target-type
+ : property-set : sources * )
+{
+ local source-types ;
+ for local s in $(sources)
+ {
+ source-types += [ $(s).type ] ;
+ }
+ local viable-source-types = [ viable-source-types-for-generator $(generator)
+ ] ;
+
+ if $(source-types) && $(viable-source-types) != * &&
+ ! [ set.intersection $(source-types) : $(viable-source-types) ]
+ {
+ local id = [ $(generator).id ] ;
+ generators.dout [ indent ] " ** generator '$(id)' pruned" ;
+ #generators.dout [ indent ] "source-types" '$(source-types)' ;
+ #generators.dout [ indent ] "viable-source-types" '$(viable-source-types)' ;
+ }
+ else
+ {
+ return [ try-one-generator-really $(project) $(name) : $(generator) :
+ $(target-type) : $(property-set) : $(sources) ] ;
+ }
+}
+
+
+rule construct-types ( project name ? : target-types + : property-set
+ : sources + )
+{
+ local result ;
+ local matched-types ;
+ local usage-requirements = [ property-set.empty ] ;
+ for local t in $(target-types)
+ {
+ local r = [ construct $(project) $(name) : $(t) : $(property-set) :
+ $(sources) ] ;
+ if $(r)
+ {
+ usage-requirements = [ $(usage-requirements).add $(r[1]) ] ;
+ result += $(r[2-]) ;
+ matched-types += $(t) ;
+ }
+ }
+ # TODO: have to introduce parameter controlling if several types can be
+ # matched and add appropriate checks.
+
+ # TODO: need to review the documentation for 'construct' to see if it should
+ # return $(source) even if nothing can be done with it. Currents docs seem
+ # to imply that, contrary to the behaviour.
+ if $(result)
+ {
+ return $(usage-requirements) $(result) ;
+ }
+ else
+ {
+ return $(usage-requirements) $(sources) ;
+ }
+}
+
+
+# Ensures all 'targets' have their type. If this is not so, exists with error.
+#
+local rule ensure-type ( targets * )
+{
+ for local t in $(targets)
+ {
+ if ! [ $(t).type ]
+ {
+ errors.error "target" [ $(t).str ] "has no type" ;
+ }
+ }
+}
+
+
+# Returns generators which can be used to construct target of specified type
+# with specified properties. Uses the following algorithm:
+# - iterates over requested target-type and all its bases (in the order returned
+# by type.all-bases).
+# - for each type find all generators that generate that type and whose
+# requirements are satisfied by properties.
+# - if the set of generators is not empty, returns that set.
+#
+# Note: this algorithm explicitly ignores generators for base classes if there
+# is at least one generator for the requested target-type.
+#
+local rule find-viable-generators-aux ( target-type : property-set )
+{
+ # Select generators that can create the required target type.
+ local viable-generators = ;
+ local generator-rank = ;
+
+ import type ;
+ local t = [ type.all-bases $(target-type) ] ;
+
+ generators.dout [ indent ] find-viable-generators target-type= $(target-type)
+ property-set= [ $(property-set).as-path ] ;
+
+ # Get the list of generators for the requested type. If no generator is
+ # registered, try base type, and so on.
+ local generators ;
+ while $(t[1])
+ {
+ generators.dout [ indent ] "trying type" $(t[1]) ;
+ if $(.generators.$(t[1]))
+ {
+ generators.dout [ indent ] "there are generators for this type" ;
+ generators = $(.generators.$(t[1])) ;
+
+ if $(t[1]) != $(target-type)
+ {
+ # We are here because there were no generators found for
+ # target-type but there are some generators for its base type.
+ # We will try to use them, but they will produce targets of
+ # base type, not of 'target-type'. So, we clone the generators
+ # and modify the list of target types.
+ local generators2 ;
+ for local g in $(generators)
+ {
+ # generators.register adds a generator to the list of
+ # generators for toolsets, which is a bit strange, but
+ # should work. That list is only used when inheriting a
+ # toolset, which should have been done before running
+ # generators.
+ generators2 += [ $(g).clone-and-change-target-type $(t[1]) :
+ $(target-type) ] ;
+ generators.register $(generators2[-1]) ;
+ }
+ generators = $(generators2) ;
+ }
+ t = ;
+ }
+ t = $(t[2-]) ;
+ }
+
+ for local g in $(generators)
+ {
+ generators.dout [ indent ] "trying generator" [ $(g).id ] "(" [ $(g).source-types ] -> [ $(g).target-types ] ")" ;
+
+ local m = [ $(g).match-rank $(property-set) ] ;
+ if $(m)
+ {
+ generators.dout [ indent ] " is viable" ;
+ viable-generators += $(g) ;
+ }
+ }
+
+ return $(viable-generators) ;
+}
+
+
+rule find-viable-generators ( target-type : property-set )
+{
+ local key = $(target-type).$(property-set) ;
+ local l = $(.fv.$(key)) ;
+ if ! $(l)
+ {
+ l = [ find-viable-generators-aux $(target-type) : $(property-set) ] ;
+ if ! $(l)
+ {
+ l = none ;
+ }
+ .fv.$(key) = $(l) ;
+ }
+
+ if $(l) = none
+ {
+ l = ;
+ }
+
+ local viable-generators ;
+ for local g in $(l)
+ {
+ # Avoid trying the same generator twice on different levels.
+ if ! $(g) in $(.active-generators)
+ {
+ viable-generators += $(g) ;
+ }
+ else
+ {
+ generators.dout [ indent ] " generator " [ $(g).id ] "is active, discaring" ;
+ }
+ }
+
+ # Generators which override 'all'.
+ local all-overrides ;
+ # Generators which are overriden.
+ local overriden-ids ;
+ for local g in $(viable-generators)
+ {
+ local id = [ $(g).id ] ;
+ local this-overrides = $(.override.$(id)) ;
+ overriden-ids += $(this-overrides) ;
+ if all in $(this-overrides)
+ {
+ all-overrides += $(g) ;
+ }
+ }
+ if $(all-overrides)
+ {
+ viable-generators = $(all-overrides) ;
+ }
+ local result ;
+ for local g in $(viable-generators)
+ {
+ if ! [ $(g).id ] in $(overriden-ids)
+ {
+ result += $(g) ;
+ }
+ }
+
+ return $(result) ;
+}
+
+
+.construct-stack = ;
+
+
+# Attempts to construct a target by finding viable generators, running them and
+# selecting the dependency graph.
+#
+local rule construct-really ( project name ? : target-type : property-set :
+ sources * )
+{
+ viable-generators = [ find-viable-generators $(target-type) :
+ $(property-set) ] ;
+
+ generators.dout [ indent ] "*** " [ sequence.length $(viable-generators) ]
+ " viable generators" ;
+
+ local result ;
+ local generators-that-succeeded ;
+ for local g in $(viable-generators)
+ {
+ # This variable will be restored on exit from this scope.
+ local .active-generators = $(g) $(.active-generators) ;
+
+ local r = [ try-one-generator $(project) $(name) : $(g) : $(target-type)
+ : $(property-set) : $(sources) ] ;
+
+ if $(r)
+ {
+ generators-that-succeeded += $(g) ;
+ if $(result)
+ {
+ ECHO "Error: ambiguity found when searching for best transformation" ;
+ ECHO "Trying to produce type '$(target-type)' from: " ;
+ for local s in $(sources)
+ {
+ ECHO " - " [ $(s).str ] ;
+ }
+ ECHO "Generators that succeeded:" ;
+ for local g in $(generators-that-succeeded)
+ {
+ ECHO " - " [ $(g).id ] ;
+ }
+ ECHO "First generator produced: " ;
+ for local t in $(result[2-])
+ {
+ ECHO " - " [ $(t).str ] ;
+ }
+ ECHO "Second generator produced: " ;
+ for local t in $(r[2-])
+ {
+ ECHO " - " [ $(t).str ] ;
+ }
+ EXIT ;
+ }
+ else
+ {
+ result = $(r) ;
+ }
+ }
+ }
+
+ return $(result) ;
+}
+
+
+# Attempts to create a target of 'target-type' with 'properties' from 'sources'.
+# The 'sources' are treated as a collection of *possible* ingridients, i.e.
+# there is no obligation to consume them all.
+#
+# Returns a list of targets. When this invocation is first instance of
+# 'construct' in stack, returns only targets of requested 'target-type',
+# otherwise, returns also unused sources and additionally generated targets.
+#
+# If 'top-level' is set, does not suppress generators that are already
+# used in the stack. This may be useful in cases where a generator
+# has to build a metatargets -- for example a target corresponding to
+# built tool.
+#
+rule construct ( project name ? : target-type : property-set * : sources * : top-level ? )
+{
+ local saved-stack ;
+ if $(top-level)
+ {
+ saved-active = $(.active-generators) ;
+ .active-generators = ;
+ }
+
+ if (.construct-stack)
+ {
+ ensure-type $(sources) ;
+ }
+
+ .construct-stack += 1 ;
+
+ increase-indent ;
+
+ if $(.debug)
+ {
+ generators.dout [ indent ] "*** construct" $(target-type) ;
+
+ for local s in $(sources)
+ {
+ generators.dout [ indent ] " from" $(s) ;
+ }
+ generators.dout [ indent ] " properties:" [ $(property-set).raw ] ;
+ }
+
+ local result = [ construct-really $(project) $(name) : $(target-type) :
+ $(property-set) : $(sources) ] ;
+
+ decrease-indent ;
+
+ .construct-stack = $(.construct-stack[2-]) ;
+
+ if $(top-level)
+ {
+ .active-generators = $(saved-active) ;
+ }
+
+ return $(result) ;
+}
+
+# Given 'result', obtained from some generator or generators.construct, adds
+# 'raw-properties' as usage requirements to it. If result already contains usage
+# requirements -- that is the first element of result of an instance of the
+# property-set class, the existing usage requirements and 'raw-properties' are
+# combined.
+#
+rule add-usage-requirements ( result * : raw-properties * )
+{
+ if $(result)
+ {
+ if [ class.is-a $(result[1]) : property-set ]
+ {
+ return [ $(result[1]).add-raw $(raw-properties) ] $(result[2-]) ;
+ }
+ else
+ {
+ return [ property-set.create $(raw-properties) ] $(result) ;
+ }
+ }
+}
+
+rule dump ( )
+{
+ for local g in $(.all-generators)
+ {
+ ECHO [ $(g).id ] ":" [ $(g).source-types ] -> [ $(g).target-types ] ;
+ }
+}
+