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ec70263fbfb6037f14ab5f6ee44f842811e098a5
build/new/generators.jam
Dave Abrahams ec70263fbf un-pluralized "target-types" in try-one-generator. 
[SVN r18370]
2003-05-08 13:33:17 +00:00

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# Copyright (C) Vladimir Prus 2002. Permission to copy, use, modify, sell and
# distribute this software is granted provided this copyright notice appears in
# all copies. This software is provided "as is" without express or implied
# warranty, and with no claim as to its suitability for any purpose.
# 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 most specific ones is selected.
#
# The most specific generators have their 'run' methods called, with the properties
# and list of sources. Each one selects 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 result.
#
# It's quite possible that 'construct' returns more targets that it was asked for.
# For example, it was asked to target type EXE, but the only found generators 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 as early as
# possible. Specifically, this is done after invoking each generator. (Later I'll
# document the rationale for trying extra target conversion at that point).
#
# That early conversion is not always desirable. Suppose a generator got a source of
# type Y and must consume one target of type X_1 and one target of type X_2.
# When converting Y to X_1 extra target of type Y_2 is created. We should not try to
# convert it to type X_1, because if we do so, the generator will get two targets
# of type X_1, and will be at loss as to which one to use. Because of that, the
# 'construct' rule has a parameter, telling if multiple targets can be returned. If
# the parameter is false, conversion of extra targets is not performed.
import class : class new is-a ;
import container : vector ;
import numbers : range ;
import utility : str equal ;
import set ;
if "--debug-generators" in [ modules.peek : ARGV ]
{
.debug = true ;
}
# Outputs a debug message if generators debugging is on.
local rule generators.dout
{
if $(.debug)
{
ECHO $(1) : $(2) : $(3) : $(4) : $(5) : $(6) : $(7) : $(8) : $(9) ;
}
}
local rule indent ( )
{
return $(.indent:J="") ;
}
local rule increase-indent ( )
{
.indent += " " ;
}
local rule decrease-indent ( )
{
.indent = $(.indent[2-]) ;
}
# Takes a vector of 'virtual-target' instances and makes a normalized
# representation, which is the same for given set of targets,
# regardless of their order.
rule normalize-target-list ( targets )
{
$(targets).sort ;
}
# Creates a generator
rule generator (
id # identifies the generator - should be name of the rule which
# sets up build actions
composing ? # whether generator processes each source target in
# turn, converting it to required types.
# Ordinary generators pass all sources together to
# recusrive generators.construct-types call.
: source-types * # types that this generator can handle
: 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). Name of generated target will be found
# by replacing % with the name of source, provided explicit name
# was not specified.
: requirements *
)
{
import generators ;
import assert ;
import generators : indent increase-indent decrease-indent generators.dout ;
import set ;
import utility : equal ;
import feature ;
import errors : error ;
self.id = $(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)
{
local m = [ MATCH ([^\\(]*)(\\((.*)%(.*)\\))? : $(e) ] ;
self.target-types += $(m[1]) ;
self.name-pre-post.$(m[1]) = $(m[3]) $(m[4]) ;
}
# Note that 'transform' here, is the same as 'for_each'.
sequence.transform type.validate : $(self.source-types) ;
if $(self.target-types) != *
{
sequence.transform type.validate : $(self.target-types) ;
}
# Add the bases of the target types to our optional properties.
# Since optional properties improve a generator's match-rank, a
# generator which requires only a base target type will not be as
# good a match as a generator which requires one of its derived
# target types (and thus has the base type as an optional
# property).
self.optional-properties
= [ feature.expand <base-target-type>$(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 cannot change depending
# 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) ;
}
# Returns the list of properties which increase this generator's
# specificity for the given target-type.
# TODO: comment is out of date.
rule optional-properties ( )
{
return $(self.optional-properties) ;
}
# Returns a number telling how well generator's properties match
# the passed properties, or an empty list if the generator can't
# be run at all.
rule match-rank ( property-set-to-match )
{
# See if generator's 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)
{
# We're only used to rank matches based on the number of
# optional properties that appear in the property set.
# That seemed a little weak to me, so I changed it: now we
# account for the number of properties and features that
# were matched as well. -- dwa 5/6/2003
return
[ sequence.length
$(all-requirements)
[ set.intersection
[ optional-properties ]
: $(properties-to-match)
]
] ;
}
}
# Returns another generator which differers from $(self) in
# - id
# - value to <toolset> feature in properties
rule clone ( new-id : new-toolset-name )
{
return [ new $(__class__) $(new-id)
: $(self.source-types)
: $(self.target-types-and-names)
: [ property.change $(self.requirements)
: toolset $(new-toolset-name)
]
] ;
}
# Tries to invoke this generator on the given sources. Returns a
# list of generated targets (instances of 'virtual-target').
rule run ( project # Project for which the targets are generated
name ? # Determines the name of 'name' attribute for
# all generated targets. See 'generated-targets' method.
: property-set # Desired properties for generated targets.
: sources + # Source targets.
: multiple ? # Allows the rule to run generator several times and return
# multiple targets of the same type. When this argument is not
# given, 'run' will return the list of targets, which is equal
# in size to the list of target types, and where type of
# each target is the same as the corresponding element of
# target type list. Non-empty value allows to return several
# such target lists, joined together.
)
{
# multiple = true ; # The tests seem to tolerate this; will
# remove the parameter altogether in the
# next revision to see what I learn -- DWA 2003/5/6
generators.dout [ indent ] " generator" $(self.id) ;
generators.dout [ indent ] " multiple:" $(mutliple) ;
generators.dout [ indent ] " composing:" $(self.composing) ;
if ! $(self.composing) && $(sources[2]) && $(self.source-types[2])
{
errors.error "Unsupported source/source-type combination" ;
}
if $(self.source-types[2])
{
multiple = ;
}
# We don't run composing generators which are not given a name.
# This in effect, means that composing generators are runnable only
# at top-level of transofrmation graph, or if name is passed explicitly.
# Thus, we dissallow composing generators in the middle. For example, the
# transofrmation CPP -> OBJ -> STATIC_LIB -> RSP -> EXE won't be allowed
# (the OBJ -> STATIC_LIB generator is composing)
if ! $(self.composing) || $(name)
{
run-really $(project) $(name) : $(property-set) : $(sources) : $(multiple) ;
}
}
rule run-really ( project name ? : property-set : sources + : multiple ? )
{
# Targets that this generator will consume directly.
local consumed = ;
# Targets that can't 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) : $(multiple)
:
: consumed bypassed ;
}
local result ;
if $(consumed)
{
result = [ construct-result $(consumed) : $(project) $(name)
: $(property-set) ] ;
result += $(bypassed) ;
}
if $(result)
{
local v = [ new vector $(result) ] ;
generators.dout [ indent ] " SUCCESS: " [ $(v).str ] ;
}
else
{
generators.dout [ indent ] " FAILURE" ;
}
generators.dout ;
return $(result) ;
}
# Constructs the dependency graph that will be returned by this
# generator
rule construct-result (
consumed + # Already prepared list of consumable targets
# If generator requires several source files will contain
# exactly len $(self.source-types) targets with matching types
# Otherwise, might contain several targets with the type of
# $(self.source-types[1])
: project name ?
: property-set # Properties to be used for all actions create here
)
{
local result ;
# If this is 1->1 transformation, apply it to all consumed targets in order.
if ! $(self.source-types[2]) && ! $(self.composing)
{
generators.dout [ indent ] "alt1" ;
for local r in $(consumed)
{
result += [ generated-targets $(r) : $(property-set) : $(project) $(name) ] ; #(targets) ;
}
}
else
{
local v = [ new vector $(consumed) ] ;
generators.dout [ indent ] "alt2 : consumed is" [ $(v).str ] ;
if $(consumed)
{
result += [ generated-targets $(consumed) : $(property-set)
: $(project) $(name) ] ;
}
}
return $(result) ;
}
# Constructs targets that are created after consuming 'sources'.
# The result will be the list of virtual-target, which the same length
# as 'target-types' attribute and with corresponding types.
#
# When 'name' is empty, all source targets must have the same value of
# the 'name' attribute, which will be used instead of the 'name' argument.
#
# The value of 'name' attribute for each generated target will be equal to
# the 'name' parameter if there's 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 if foo.z, then created files would
# be "foo.t1" and "foo_x.t2". The 'name' attribute actually determined the
# basename of a file.
#
# Note that this pattern mechanism has nothing to do with implicit patterns
# in make. It's a way to produce target which name is different for name of
# source.
rule generated-targets ( sources + : property-set : project name ? )
{
if ! $(name)
{
name = [ $(sources[1]).name ] ;
for local s in $(sources[2])
{
if [ $(s).name ] != $(name)
{
error "$(self.id): source targets have different names: cannot determine target name" ;
}
}
# Names of sources might include directory. We should strip it.
name = $(name:D=) ;
}
# Create generated target for each target type.
local targets ;
for local t in $(self.target-types)
{
local generated-name ;
if $(self.name-pre-post.$(t))
{
generated-name = [ sequence.join $(self.name-pre-post.$(t)[1]) $(name) $(self.name-pre-post.$(t)[2]) ] ;
}
else
{
generated-name = $(name) ;
}
targets += [ new file-target $(generated-name) : $(t) : $(project) ] ;
}
# Assign an action for each target
local action = [ action-class ] ;
local a = [ new $(action) $(targets) : $(sources) : $(self.id) :
$(property-set) ] ;
for local t in $(targets)
{
$(t).action $(a) ;
}
return [ sequence.transform virtual-target.register : $(targets) ] ;
}
# Attempts to convert 'source' to the types that this generator can
# handle. The intention is to produce the set of targets can should be
# used when generator is run.
rule convert-to-consumable-types ( project name ? :
property-set : sources + : multiple ?
: only-one ? # convert 'source' to only one of source types
# if there's more that one possibility, report an
# error
: consumed-var # name of variable which recieves all targets which
# can be consumed.
bypassed-var # name variable which recieves all targets which
# cannot be consumed
)
{
# We're likely to be passed 'consumed' and 'bypassed'
# var names. Use "_" to avoid name conflicts.
local _consumed ;
local _bypassed ;
local missing-types ;
if $(sources[2])
{
# Don't 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 consuned/bypassed separation should
# be done by 'construct-types'.
if $(missing-types)
{
local transformed = [ generators.construct-types $(project) $(name)
: $(missing-types) : $(multiple) : $(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's no need to rerun it on targets of different types.
for local t in $(transformed)
{
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 don't 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' won't allow two different
# instances. Therefore, it's OK to use 'set.difference'.
_bypassed = [ set.difference $(_bypassed) : $(_consumed) ] ;
$(consumed-var) += $(_consumed) ;
$(bypassed-var) += $(_bypassed) ;
}
# Converts several files to consumable types.
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.
local failed ;
while $(sources) && ! $(failed)
{
local _c ;
local _b ;
# TODO: need to check for failure on each source.
convert-to-consumable-types $(project) : $(property-set)
: $(sources[1]) : * : true : _c _b ;
if ! $(_c)
{
generators.dout [ indent ] " failed to convert " [ $(sources[1]).str ] ;
# failed = true ;
}
$(consumed-var) += $(_c) ;
$(bypassed-var) += $(_b) ;
sources = $(sources[2-]) ;
}
if $(failed)
{
$(consumed-var) = ;
$(bypassed-var) = ;
}
}
rule consume-directly ( source : consumed-var : missing-types-var )
{
local real-source-type = [ $(source).type ] ;
for local st in $(self.source-types)
{
# The 'source' if of 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" ;
}
}
class generator ;
import errors : error ;
.generators = ;
# Registers new generator instance 'g'.
rule register ( g )
{
.generators += $(g) ;
for local t in [ $(g).target-types ]
{
.generators.$(t) += $(g) ;
}
# Update the set of generators for toolset
local id = [ $(g).id ] ;
.generators-for-toolset.$(id:S=) += $(g) ;
}
# Creates new instance of the 'generator' class and registers it.
rule register-standard ( id : source-types + : target-types + : requirements * )
{
local g = [ new generator $(id) : $(source-types) : $(target-types)
: $(requirements) ] ;
register $(g) ;
}
# Creates new instance of the 'composing-generator' class 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) ;
}
# Returns all generators which belong to 'toolset', i.e. which
# ids are $(toolset).<something>
rule generators-for-toolset ( toolset )
{
return $(.generators-for-toolset.$(toolset)) ;
}
# Set if results of the current generators search are going to be cached
# This means no futher attempts to cache generators search should be
# made.
.caching = ;
# For all t in 'targets':
# if [ $(t).type ] in $(target-types), add 't' to result
# if [ $(t).type ] in base type for any of 'target-types', add 't' to result
# otherwise, add 't' to extra.
rule base-to-derived-type-conversion ( targets * : target-types +
: result-var extra-var )
{
for local t in $(targets)
{
if [ $(t).type ] in $(target-types)
{
$(result-var) += $(t) ;
}
else
{
# We might have asked for a type 'D', but found only generator for
# a type 'B', where 'D' is derived from 'B'. In this case, the
# generation succeeds, but we should change type of the generated target.
local at = [ $(t).type ] ;
local found ;
for local tt in $(target-types)
{
if ! $(found) && [ type.is-derived $(tt) $(at) ]
{
$(t).set-type $(tt) ;
$(result-var) += $(t) ;
found = 1 ;
}
}
if ! $(found)
{
$(extra-var) += $(t) ;
}
}
}
}
local rule try-one-generator ( project name ? : generator multiple ? :
target-type : property-set : sources * )
{
local targets =
[ $(generator).run $(project) $(name)
: $(property-set)
: $(sources)
: $(multiple)
] ;
# Generated targets that are of required types
local result ;
# Generated target of other types.
local extra ;
base-to-derived-type-conversion $(targets) : $(target-type)
: result extra ;
# Now try to convert extra targets
# 'construct' will to its best to return only requested
# target types, so if we receive any extra from that call,
# we don't try to do anything about them.
local extra2 ;
if $(multiple)
{
for local e in $(extra)
{
local try2 = [ construct-types $(project) $(name)
: $(target-type)
:
: $(property-set)
: $(e) ] ;
result += $(try2) ;
}
}
else
{
extra2 = $(extra) ;
}
local rr = [ new vector [ new vector $(result) ]
[ new vector $(extra2) ] ] ;
generators.dout [ indent ] " generator" [ $(generator).id ] " spawned " ;
generators.dout [ indent ] " " [ $(rr).str ] ;
return $(result) $(extra2) ;
}
rule construct-types ( project name ? : target-types + : multiple ? :
property-set : sources + )
{
local result ;
local matched-types ;
for local t in $(target-types)
{
local r = [ construct $(project) $(name) : $(t) $(multiple) : $(property-set) :
$(sources) ] ;
if $(r)
{
result += $(r) ;
matched-types += $(t) ;
}
}
# TODO: have to introduce parameter controlling if
# several types can be matches 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 $(result) ;
}
else
{
return $(sources) ;
}
}
# Ensures all 'targets' have types. 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 it's bases (in the order returned bt
# type.all-bases.
# - for each type find all generators that generate that type and which 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's
# at least one generator for requested target-type.
local rule find-viable-generators ( target-type : property-set )
{
# Select generators that can create the required target type.
local viable-generators = ;
local generator-rank = ;
import type ;
# Try all-type generators first. Assume they have
# quite specific requirements.
local t = * [ type.all-bases $(target-type) ] ;
generators.dout [ indent ] find-viable-generators target-type= $(target-type)
property-set= [ $(property-set).as-path ]
;
while $(t[1])
{
generators.dout [ indent ] "trying type" $(t[1]) ;
for local g in $(.generators.$(t[1]))
{
generators.dout [ indent ] "trying generator" [ $(g).source-types ] -> [ $(g).target-types ] ;
# Avoid trying the same generator twice on different levels.
if ! $(g) in $(.active-generators)
{
local m = [ $(g).match-rank $(property-set) ] ;
if $(m)
{
generators.dout [ indent ] " matched with rank" $(m) ;
viable-generators += $(g) ;
generator-rank += $(m) ;
t = ;
}
}
}
t = $(t[2-]) ;
}
return [ sequence.select-highest-ranked $(viable-generators) : $(generator-rank) ] ;
}
# Given a vector of vectors, of of them represents results of running some
# generator, returns the 'best' result, it it exists. Otherwise, exit with
# and error. Result is returned as plain jam list.
local rule select-dependency-graph ( options )
{
if [ $(options).size ] = 0
{
return ;
}
else if [ $(options).size ] = 1
{
return [ $(options).get-at 1 ] ;
}
else
{
# We have several alternatives and need to check if they
# are the same.
for local r in [ $(options).get ]
{
normalize-target-list $(r) ;
generators.dout [ $(r).str ] ;
}
local f = [ $(options).at 1 ] ;
local mismatch ;
for local r in [ $(results).get ]
{
if ! [ utility.equal $(r) $(f) ]
{
mismatch = true ;
}
}
if ! $(mismatch)
{
return [ $(f).get ] ;
}
else
{
error [ $(options).size ] "possible generations for "
$(target-types) "Can't handle this now." ;
}
}
}
.construct-stack = ;
# Attempt to construct the target by looking at transformation cache.
local rule construct-with-caching (
project name ? : target-type multiple ? : property-set : sources * )
{
local result ;
# Caching is only possible when we're not computing cacheable transformation
# already, when there's only one source which has no action -- i.e. source file,
# and name of target is not specified.
if ! $(.caching) && ! $(sources[2]) && $(sources[1]) && ! $(name)
&& ! [ $(sources[1]).action ]
{
local .caching = true ;
local t = $(sources[1]) ;
local signature = [ sequence.join [ $(t).type ] $(target-type) $(property-set) : - ] ;
# Get a transformation template from cache or create it.
local cresult ;
if $(.transformation.cache.$(signature))
{
cresult = $(.transformation.cache.$(signature)) ;
}
else
{
local ut = [ new file-target % : [ $(t).type ] : "no project" ] ;
cresult = [ construct $(project) : $(target-type) $(multiple)
: $(property-set) : $(ut) ] ;
.transformation.cache.$(signature) = $(cresult) ;
}
# Substitute the real source name in the transformation template.
if $(cresult)
{
generators.dout [ indent ] "*** putting to cache?" ;
for local c in $(cresult)
{
local cc = [ virtual-target.clone-template $(c) : $(t) ] ;
generators.dout [ indent ] "*** cloning " [ $(c).str ] ;
generators.dout [ indent ] "*** cloned" $(cc) --- [ $(cc).str ] ;
result += $(cc) ;
}
}
}
return $(result) ;
}
# Attempts to construct target by finding viable generators, running them
# and selecting the dependency graph
local rule construct-without-caching (
project name ? : target-type multiple ? : property-set : sources * )
{
viable-generators = [ find-viable-generators $(target-type) : $(property-set) ] ;
local results = [ new vector ] ;
generators.dout [ indent ] "*** " [ sequence.length $(viable-generators) ]
" viable generators" ;
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) $(multiple) : $(target-type) :
$(property-set) : $(sources) ] ;
if $(r)
{
$(results).push-back [ new vector $(r) ] ;
}
}
return [ select-dependency-graph $(results) ] ;
}
# Attempts to create target of 'target-type' with 'properties'
# from 'sources'. The 'sources' are treated as a collection of
# *possible* ingridients -- i.e. it is not required to consume
# them all. If 'multiple' is true, the rule is allowed to return
# several targets of 'target-type'.
#
#
# Returns a list of target. 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.
rule construct ( project name ? : target-type multiple ? : property-set * : sources * )
{
if (.construct-stack)
{
ensure-type $(sources) ;
}
.construct-stack += 1 ;
increase-indent ;
local m ;
if $(multiple)
{
m = "(may return multiple targets)" ;
}
generators.dout [ indent ] "*** construct" $(target-type) $(m) ;
for local s in $(sources)
{
generators.dout [ indent ] " from" [ $(s).str ] ;
}
generators.dout [ indent ] " properties:" [ $(property-set).raw ] ;
local result = [ construct-with-caching $(project) $(name)
: $(target-type) $(multiple) : $(property-set) : $(sources) ] ;
if ! $(result) {
result = [ construct-without-caching $(project) $(name)
: $(target-type) $(multiple) : $(property-set) : $(sources) ] ;
}
decrease-indent ;
.construct-stack = $(.construct-stack[2-]) ;
if ! $(.construct-stack) # This is first invocation in stack
{
local result2 ;
for local t in $(result)
{
local type = [ $(t).type ] ;
assert.nonempty-variable type ;
assert.nonempty-variable target-type ;
if $(type) = $(target-type) || [ type.is-derived $(type) $(target-type) ]
{
result2 += $(t) ;
}
}
return $(result2) ;
}
else
{
return $(result) ;
}
}
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