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diff --git a/tools/build/src/kernel/modules.jam b/tools/build/src/kernel/modules.jam
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+# Copyright 2003 Dave Abrahams
+# Copyright 2003, 2005 Vladimir Prus
+# 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)
+
+# Essentially an include guard; ensures that no module is loaded multiple times.
+.loaded ?= ;
+
+# A list of modules currently being loaded for error reporting of circular
+# dependencies.
+.loading ?= ;
+
+# A list of modules needing to be tested using their __test__ rule.
+.untested ?= ;
+
+# A list of modules which have been tested using their __test__ rule.
+.tested ?= ;
+
+
+# Runs internal Boost Build unit tests for the specified module. The module's
+# __test__ rule is executed in its own module to eliminate any inadvertent
+# effects of testing module dependencies (such as assert) on the module itself.
+#
+local rule run-module-test ( m )
+{
+    local tested-modules = [ modules.peek modules : .tested ] ;
+
+    if ( ! $(m) in $(tested-modules) )  # Avoid recursive test invocations.
+        && ( ( --debug in $(argv) ) || ( --debug-module=$(m) in $(argv) ) )
+    {
+        modules.poke modules : .tested : $(tested-modules) $(m) ;
+
+        if ! ( __test__ in [ RULENAMES $(m) ] )
+        {
+            local argv = [ peek : ARGV ] ;
+            if ! ( --quiet in $(argv) ) && ( --debug-tests in $(argv) )
+            {
+                ECHO warning: no __test__ rule defined in module $(m) ;
+            }
+        }
+        else
+        {
+            if ! ( --quiet in $(argv) )
+            {
+                ECHO testing module $(m)... ;
+            }
+
+            local test-module = __test-$(m)__ ;
+            IMPORT $(m) : [ RULENAMES $(m) ] : $(test-module) : [ RULENAMES $(m)
+                ] ;
+            IMPORT $(m) : __test__ : $(test-module) : __test__ : LOCALIZE ;
+            module $(test-module)
+            {
+                __test__ ;
+            }
+        }
+    }
+}
+
+
+# Return the binding of the given module.
+#
+rule binding ( module )
+{
+    return $($(module).__binding__) ;
+}
+
+
+# Sets the module-local value of a variable. This is the most reliable way to
+# set a module-local variable in a different module; it eliminates issues of
+# name shadowing due to dynamic scoping.
+#
+rule poke ( module-name ? : variables + : value * )
+{
+    module $(<)
+    {
+        $(>) = $(3) ;
+    }
+}
+
+
+# Returns the module-local value of a variable. This is the most reliable way to
+# examine a module-local variable in a different module; it eliminates issues of
+# name shadowing due to dynamic scoping.
+#
+rule peek ( module-name ? : variables + )
+{
+    module $(<)
+    {
+        return $($(>)) ;
+    }
+}
+
+
+# Call the given rule locally in the given module. Use this for rules accepting
+# rule names as arguments, so that the passed rule may be invoked in the context
+# of the rule's caller (for example, if the rule accesses module globals or is a
+# local rule). Note that rules called this way may accept at most 18 parameters.
+#
+rule call-in ( module-name ? : rule-name args * : * )
+{
+    module $(module-name)
+    {
+        return [ $(2) : $(3) : $(4) : $(5) : $(6) : $(7) : $(8) : $(9) : $(10) :
+            $(11) : $(12) : $(13) : $(14) : $(15) : $(16) : $(17) : $(18) :
+            $(19) ] ;
+    }
+}
+
+
+# Given a possibly qualified rule name and arguments, remove any initial module
+# qualification from the rule and invoke it in that module. If there is no
+# module qualification, the rule is invoked in the global module. Note that
+# rules called this way may accept at most 18 parameters.
+#
+rule call-locally ( qualified-rule-name args * : * )
+{
+    local module-rule = [ MATCH (.*)\\.(.*) : $(qualified-rule-name) ] ;
+    local rule-name = $(module-rule[2]) ;
+    rule-name ?= $(qualified-rule-name) ;
+    #   We pass only 18 parameters here since Boost Jam allows at most 19 rule
+    # parameter positions and the call-in rule already uses up the initial
+    # position for the module name.
+    return [ call-in $(module-rule[1]) : $(rule-name) $(args) : $(2) : $(3) :
+        $(4) : $(5) : $(6) : $(7) : $(8) : $(9) : $(10) : $(11) : $(12) : $(13)
+        $(14) : $(15) : $(16) : $(17) : $(18) : $(19) ] ;
+}
+
+
+# Load the indicated module if it is not already loaded.
+#
+rule load (
+      module-name  # Name of module to load. Rules will be defined in this
+                   # module.
+    : filename ?   # (partial) path to file; Defaults to $(module-name).jam.
+    : search *     # Directories in which to search for filename. Defaults to
+                   # $(BOOST_BUILD_PATH).
+)
+{
+    # Avoid loading modules twice.
+    if ! ( $(module-name) in $(.loaded) )
+    {
+        filename ?= $(module-name).jam ;
+
+        # Mark the module loaded so we do not try to load it recursively.
+        .loaded += $(module-name) ;
+
+        # Suppress tests if any module loads are already in progress.
+        local suppress-test = $(.loading[1]) ;
+
+        # Push this module on the loading stack.
+        .loading += $(module-name) ;
+
+        # Remember that it is untested.
+        .untested += $(module-name) ;
+
+        # Insert the new module's __name__ and __file__ globals.
+        poke $(module-name) : __name__ : $(module-name) ;
+        poke $(module-name) : __file__ : $(filename) ;
+
+        module $(module-name)
+        {
+            # Add some grist so that the module will have a unique target name.
+            local module-target = $(__file__:G=module@) ;
+
+            local search = $(3) ;
+            search ?= [ modules.peek : BOOST_BUILD_PATH ] ;
+            SEARCH on $(module-target) = $(search) ;
+            BINDRULE on $(module-target) = modules.record-binding ;
+
+            include $(module-target) ;
+
+            # Allow the module to see its own names with full qualification.
+            local rules = [ RULENAMES $(__name__) ] ;
+            IMPORT $(__name__) : $(rules) : $(__name__) : $(__name__).$(rules) ;
+        }
+
+        if $(module-name) != modules && ! [ binding $(module-name) ]
+        {
+            import errors ;
+            errors.error "Could not find module" $(module-name) in $(search) ;
+        }
+
+        # Pop the loading stack. Must happen before testing or we will run into
+        # a circular loading dependency.
+        .loading = $(.loading[1--2]) ;
+
+        # Run any pending tests if this is an outer load.
+        if ! $(suppress-test)
+        {
+            local argv = [ peek : ARGV ] ;
+            for local m in $(.untested)
+            {
+                run-module-test $(m) ;
+            }
+            .untested = ;
+        }
+    }
+    else if $(module-name) in $(.loading)
+    {
+        import errors ;
+        errors.error loading \"$(module-name)\"
+            : circular module loading dependency:
+            : $(.loading)" ->" $(module-name) ;
+    }
+}
+
+
+# This helper is used by load (above) to record the binding (path) of each
+# loaded module.
+#
+rule record-binding ( module-target : binding )
+{
+    $(.loading[-1]).__binding__ = $(binding) ;
+}
+
+
+# Transform each path in the list, with all backslashes converted to forward
+# slashes and all detectable redundancy removed. Something like this is probably
+# needed in path.jam, but I am not sure of that, I do not understand it, and I
+# am not ready to move all of path.jam into the kernel.
+#
+local rule normalize-raw-paths ( paths * )
+{
+    local result ;
+    for p in $(paths:T)
+    {
+        result += [ NORMALIZE_PATH $(p) ] ;
+    }
+    return $(result) ;
+}
+
+
+.cwd = [ PWD ] ;
+
+
+# Load the indicated module and import rule names into the current module. Any
+# members of rules-opt will be available without qualification in the caller's
+# module. Any members of rename-opt will be taken as the names of the rules in
+# the caller's module, in place of the names they have in the imported module.
+# If rules-opt = '*', all rules from the indicated module are imported into the
+# caller's module. If rename-opt is supplied, it must have the same number of
+# elements as rules-opt.
+#
+rule import ( module-names + : rules-opt * : rename-opt * )
+{
+    if ( $(rules-opt) = * || ! $(rules-opt) ) && $(rename-opt)
+    {
+        import errors ;
+        errors.error "Rule aliasing is only available for explicit imports." ;
+    }
+
+    if $(module-names[2]) && ( $(rules-opt) || $(rename-opt) )
+    {
+        import errors ;
+        errors.error "When loading multiple modules, no specific rules or"
+            "renaming is allowed" ;
+    }
+
+    local caller = [ CALLER_MODULE ] ;
+
+    # Import each specified module
+    for local m in $(module-names)
+    {
+        if ! $(m) in $(.loaded)
+        {
+            # If the importing module is not already in the BOOST_BUILD_PATH,
+            # prepend it to the path.  We do not want to invert the search order
+            # of modules that are already there.
+
+            local caller-location ;
+            if $(caller)
+            {
+                caller-location = [ binding $(caller) ] ;
+                caller-location = $(caller-location:D) ;
+                caller-location = [ normalize-raw-paths
+                    $(caller-location:R=$(.cwd)) ] ;
+            }
+
+            local search = [ peek : BOOST_BUILD_PATH ] ;
+            search = [ normalize-raw-paths $(search:R=$(.cwd)) ] ;
+
+            if $(caller-location) && ! $(caller-location) in $(search)
+            {
+                search = $(caller-location) $(search) ;
+            }
+
+            load $(m) : : $(search) ;
+        }
+
+        IMPORT_MODULE $(m) : $(caller) ;
+
+        if $(rules-opt)
+        {
+            local source-names ;
+            if $(rules-opt) = *
+            {
+                local all-rules = [ RULENAMES $(m) ] ;
+                source-names = $(all-rules) ;
+            }
+            else
+            {
+                source-names = $(rules-opt) ;
+            }
+            local target-names = $(rename-opt) ;
+            target-names ?= $(source-names) ;
+            IMPORT $(m) : $(source-names) : $(caller) : $(target-names) ;
+        }
+    }
+}
+
+
+# Define exported copies in $(target-module) of all rules exported from
+# $(source-module). Also make them available in the global module with
+# qualification, so that it is just as though the rules were defined originally
+# in $(target-module).
+#
+rule clone-rules ( source-module target-module )
+{
+    local r = [ RULENAMES $(source-module) ] ;
+    IMPORT $(source-module) : $(r) : $(target-module) : $(r) : LOCALIZE ;
+    EXPORT $(target-module) : $(r) ;
+    IMPORT $(target-module) : $(r) : : $(target-module).$(r) ;
+}
+
+
+# These rules need to be available in all modules to implement module loading
+# itself and other fundamental operations.
+local globalize = peek poke record-binding ;
+IMPORT modules : $(globalize) : : modules.$(globalize) ;
+
+
+rule __test__ ( )
+{
+    import assert ;
+    import modules : normalize-raw-paths ;
+
+    module modules.__test__
+    {
+        foo = bar ;
+    }
+
+    assert.result bar : peek modules.__test__ : foo ;
+
+    poke modules.__test__ : foo : bar baz ;
+    assert.result bar baz : peek modules.__test__ : foo ;
+
+    assert.result c:/foo/bar : normalize-raw-paths c:/x/../foo/./xx/yy/../../bar ;
+    assert.result .          : normalize-raw-paths .                             ;
+    assert.result ..         : normalize-raw-paths ..                            ;
+    assert.result ../..      : normalize-raw-paths ../..                         ;
+    assert.result ..         : normalize-raw-paths ./..                          ;
+    assert.result / /        : normalize-raw-paths / \\                          ;
+    assert.result a          : normalize-raw-paths a                             ;
+    assert.result a          : normalize-raw-paths a/                            ;
+    assert.result /a         : normalize-raw-paths /a/                           ;
+    assert.result /          : normalize-raw-paths /a/..                         ;
+}