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+// file : libbuild2/algorithm.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_ALGORITHM_HXX
+#define LIBBUILD2_ALGORITHM_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/action.hxx>
+#include <libbuild2/target.hxx>
+
+#include <libbuild2/export.hxx>
+
+namespace build2
+{
+ class scope;
+ class prerequisite;
+ class prerequisite_key;
+
+ // The default prerequisite search implementation. It first calls the
+ // prerequisite-type-specific search function. If that doesn't yeld
+ // anything, it creates a new target.
+ //
+ const target&
+ search (const target&, const prerequisite&);
+
+ // As above but only search for an already existing target.
+ //
+ const target*
+ search_existing (const prerequisite&);
+
+ // As above but cache a target searched in a custom way.
+ //
+ const target&
+ search_custom (const prerequisite&, const target&);
+
+ // As above but specify the prerequisite to search as a key.
+ //
+ LIBBUILD2_SYMEXPORT const target&
+ search (const target&, const prerequisite_key&);
+
+ LIBBUILD2_SYMEXPORT const target*
+ search_existing (const prerequisite_key&);
+
+ // Uniform search interface for prerequisite/prerequisite_member.
+ //
+ inline const target&
+ search (const target& t, const prerequisite_member& p) {return p.search (t);}
+
+ // As above but override the target type. Useful for searching for
+ // target group members where we need to search for a different
+ // target type.
+ //
+ const target&
+ search (const target&, const target_type&, const prerequisite_key&);
+
+ // As above but specify the prerequisite to search as individual key
+ // components. Scope can be NULL if the directory is absolute.
+ //
+ const target&
+ search (const target&,
+ const target_type& type,
+ const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ const string* ext = nullptr, // NULL means unspecified.
+ const scope* = nullptr, // NULL means dir is absolute.
+ const optional<project_name>& proj = nullopt);
+
+ const target*
+ search_existing (const target_type& type,
+ const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ const string* ext = nullptr,
+ const scope* = nullptr,
+ const optional<project_name>& proj = nullopt);
+
+ // As above but specify the target type as template argument.
+ //
+ template <typename T>
+ const T&
+ search (const target&,
+ const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ const string* ext = nullptr,
+ const scope* = nullptr);
+
+ // Search for a target identified by the name. The semantics is "as if" we
+ // first created a prerequisite based on this name in exactly the same way
+ // as the parser would and then searched based on this prerequisite.
+ //
+ LIBBUILD2_SYMEXPORT const target&
+ search (const target&, name, const scope&);
+
+ // Unlike the above version, this one can be called during the execute
+ // phase. Return NULL for unknown target types.
+ //
+ LIBBUILD2_SYMEXPORT const target*
+ search_existing (const name&,
+ const scope&,
+ const dir_path& out = dir_path ());
+
+ // Target match lock: a non-const target reference and the target::offset_*
+ // state that has already been "achieved". Note that target::task_count
+ // itself is set to busy for the duration or the lock. While at it we also
+ // maintain a stack of active locks in the current dependency chain (used to
+ // detect dependency cycles).
+ //
+ struct LIBBUILD2_SYMEXPORT target_lock
+ {
+ using action_type = build2::action;
+ using target_type = build2::target;
+
+ action_type action;
+ target_type* target = nullptr;
+ size_t offset = 0;
+
+ explicit operator bool () const {return target != nullptr;}
+
+ void
+ unlock ();
+
+ // Movable-only type with move-assignment only to NULL lock.
+ //
+ target_lock () = default;
+ target_lock (target_lock&&);
+ target_lock& operator= (target_lock&&);
+
+ target_lock (const target_lock&) = delete;
+ target_lock& operator= (const target_lock&) = delete;
+
+ // Implementation details.
+ //
+ ~target_lock ();
+ target_lock (action_type, target_type*, size_t);
+
+ struct data
+ {
+ action_type action;
+ target_type* target;
+ size_t offset;
+ };
+
+ data
+ release ();
+
+ // Tip of the stack.
+ //
+ static const target_lock*
+ stack () noexcept;
+
+ // Set the new and return the previous tip of the stack.
+ //
+ static const target_lock*
+ stack (const target_lock*) noexcept;
+
+ const target_lock* prev;
+
+ void
+ unstack ();
+
+ struct stack_guard
+ {
+ explicit stack_guard (const target_lock* s): s_ (stack (s)) {}
+ ~stack_guard () {stack (s_);}
+ const target_lock* s_;
+ };
+ };
+
+ // If this target is already locked in this dependency chain, then return
+ // the corresponding lock. Return NULL otherwise (so can be used a boolean
+ // predicate).
+ //
+ const target_lock*
+ dependency_cycle (action, const target&);
+
+ // If the target is already applied (for this action) or executed, then no
+ // lock is acquired. Otherwise, the target must not yet be matched for this
+ // action.
+ //
+ // @@ MT fuzzy: what if it is already in the desired state, why assert?
+ // Currently we only use it with match_recipe() and if it is matched
+ // but not applied, then it's not clear why we are overriding that
+ // match.
+ //
+ target_lock
+ lock (action, const target&);
+
+ // Add an ad hoc member to the end of the chain assuming that an already
+ // existing member of this target type is the same. Return the newly added
+ // or already existing target. The member directories (dir and out) are
+ // expected to be absolute and normalized.
+ //
+ // Note that here and in find_adhoc_member() below (as well as in
+ // perform_clean_extra()) we use target type (as opposed to, say, type and
+ // name) as the member's identity. This fits our current needs where every
+ // (rule-managed) ad hoc member has a unique target type and we have no need
+ // for multiple members of the same type. This also allows us to support
+ // things like changing the ad hoc member name by declaring it in a
+ // buildfile.
+ //
+ LIBBUILD2_SYMEXPORT target&
+ add_adhoc_member (target&,
+ const target_type&,
+ const dir_path& dir,
+ const dir_path& out,
+ string name);
+
+ // If the extension is specified then it is added to the member's target
+ // name.
+ //
+ target&
+ add_adhoc_member (target&, const target_type&, const char* ext = nullptr);
+
+ template <typename T>
+ inline T&
+ add_adhoc_member (target& g, const target_type& tt, const char* e = nullptr)
+ {
+ return static_cast<T&> (add_adhoc_member (g, tt, e));
+ }
+
+ template <typename T>
+ inline T&
+ add_adhoc_member (target& g, const char* e = nullptr)
+ {
+ return add_adhoc_member<T> (g, T::static_type, e);
+ }
+
+ // Find an ad hoc member of the specified target type returning NULL if not
+ // found.
+ //
+ target*
+ find_adhoc_member (target&, const target_type&);
+
+ const target*
+ find_adhoc_member (const target&, const target_type&);
+
+ template <typename T>
+ inline T*
+ find_adhoc_member (target& g, const target_type& tt)
+ {
+ return static_cast<T*> (find_adhoc_member (g, tt));
+ }
+
+ template <typename T>
+ inline const T*
+ find_adhoc_member (const target& g, const target_type& tt)
+ {
+ return static_cast<const T*> (find_adhoc_member (g, tt));
+ }
+
+ template <typename T>
+ inline const T*
+ find_adhoc_member (const target& g)
+ {
+ return find_adhoc_member<T> (g, T::static_type);
+ }
+
+ template <typename T>
+ inline T*
+ find_adhoc_member (target& g)
+ {
+ return find_adhoc_member<T> (g, T::static_type);
+ }
+
+ // Match and apply a rule to the action/target with ambiguity detection.
+ // Increment the target's dependents count, which means that you should call
+ // this function with the intent to also call execute(). Return the target
+ // state translating target_state::failed to the failed exception unless
+ // instructed otherwise.
+ //
+ // The try_match() version doesn't issue diagnostics if there is no rule
+ // match (but fails as match() for all other errors, like rule ambiguity,
+ // inability to apply, etc). The first half of the result indicated whether
+ // there was a rule match.
+ //
+ // The unmatch argument allows optimizations that avoid calling execute().
+ // If it is unmatch::unchanged then only unmatch the target if it is known
+ // to be unchanged after match. If it is unmatch::safe, then unmatch the
+ // target if it is safe (this includes unchanged or if we know that someone
+ // else will execute this target). Return true if unmatch succeeded. Always
+ // throw if failed.
+ //
+ enum class unmatch {none, unchanged, safe};
+
+ target_state
+ match (action, const target&, bool fail = true);
+
+ pair<bool, target_state>
+ try_match (action, const target&, bool fail = true);
+
+ bool
+ match (action, const target&, unmatch);
+
+ // Start asynchronous match. Return target_state::postponed if the
+ // asynchrounous operation has been started and target_state::busy if the
+ // target has already been busy. Regardless of the result, match() must be
+ // called in order to complete the operation (except target_state::failed).
+ //
+ // If fail is false, then return target_state::failed if the target match
+ // failed. Otherwise, throw the failed exception if keep_going is false and
+ // return target_state::failed otherwise.
+ //
+ target_state
+ match_async (action, const target&,
+ size_t start_count, atomic_count& task_count,
+ bool fail = true);
+
+ // Match by specifying the recipe directly and without incrementing the
+ // dependency counts. The target must be locked.
+ //
+ void
+ match_recipe (target_lock&, recipe);
+
+ // Match a "delegate rule" from withing another rules' apply() function
+ // avoiding recursive matches (thus the third argument). Unless try_match is
+ // true, fail if no rule is found. Otherwise return empty recipe. Note that
+ // unlike match(), this function does not increment the dependents count and
+ // the two rules must coordinate who is using the target's data pad and/or
+ // prerequisite_targets. See also the companion execute_delegate().
+ //
+ recipe
+ match_delegate (action, target&, const rule&, bool try_match = false);
+
+ // Match a rule for the inner operation from withing the outer rule's
+ // apply() function. See also the companion execute_inner().
+ //
+ target_state
+ match_inner (action, const target&);
+
+ bool
+ match_inner (action, const target&, unmatch);
+
+ // The standard prerequisite search and match implementations. They call
+ // search() (unless a custom is provided) and then match() (unless custom
+ // returned NULL) for each prerequisite in a loop omitting out of project
+ // prerequisites for the clean operation. If this target is a member of a
+ // group, then first do this to the group's prerequisites.
+ //
+ using match_search = function<
+ prerequisite_target (action,
+ const target&,
+ const prerequisite&,
+ include_type)>;
+
+ void
+ match_prerequisites (action, target&, const match_search& = nullptr);
+
+ // As above but go into group members.
+ //
+ // Note that if we cleaning, this function doesn't go into group members, as
+ // an optimization (the group should clean everything up).
+ //
+ using match_search_member = function<
+ prerequisite_target (action,
+ const target&,
+ const prerequisite_member&,
+ include_type)>;
+
+ void
+ match_prerequisite_members (action, target&,
+ const match_search_member& = nullptr);
+
+ // As above but omit prerequisites that are not in the specified scope.
+ //
+ void
+ match_prerequisites (action, target&, const scope&);
+
+ void
+ match_prerequisite_members (action, target&, const scope&);
+
+ // Match (already searched) members of a group or similar prerequisite-like
+ // dependencies. Similar in semantics to match_prerequisites(). Any marked
+ // target pointers are skipped.
+ //
+ // T can only be const target* or prerequisite_target.
+ //
+ template <typename T>
+ void
+ match_members (action, target&, T const*, size_t);
+
+ template <size_t N>
+ inline void
+ match_members (action a, target& t, const target* (&ts)[N])
+ {
+ match_members (a, t, ts, N);
+ }
+
+ inline void
+ match_members (action a,
+ target& t,
+ prerequisite_targets& ts,
+ size_t start = 0)
+ {
+ match_members (a, t, ts.data () + start, ts.size () - start);
+ }
+
+ // Unless already known, match, and, if necessary, execute the group in
+ // order to resolve its members list. Note that even after that the member's
+ // list might still not be available (e.g., if some wildcard/ fallback rule
+ // matched).
+ //
+ // If the action is for an outer operation, then it is changed to inner
+ // which means the members are always resolved by the inner (e.g., update)
+ // rule. This feels right since this is the rule that will normally do the
+ // work (e.g., update) and therefore knows what it will produce (and if we
+ // don't do this, then the group resolution will be racy since we will use
+ // two different task_count instances for synchronization).
+ //
+ group_view
+ resolve_members (action, const target&);
+
+ // Unless already known, match the target in order to resolve its group.
+ //
+ // Unlike the member case, a rule can only decide whether a target is a
+ // member of the group in its match() since otherwise it (presumably) should
+ // not match (and some other rule may).
+ //
+ // If the action is for an outer operation, then it is changed to inner, the
+ // same as for members.
+ //
+ const target*
+ resolve_group (action, const target&);
+
+ // Inject dependency on the target's directory fsdir{}, unless it is in the
+ // src tree or is outside of any project (say, for example, an installation
+ // directory). If the parent argument is true, then inject the parent
+ // directory of a target that is itself a directory (name is empty). Return
+ // the injected target or NULL. Normally this function is called from the
+ // rule's apply() function.
+ //
+ // As an extension, this function will also search for an existing fsdir{}
+ // prerequisite for the directory and if one exists, return that (even if
+ // the target is in src tree). This can be used, for example, to place
+ // output into an otherwise non-existent directory.
+ //
+ LIBBUILD2_SYMEXPORT const fsdir*
+ inject_fsdir (action, target&, bool parent = true);
+
+ // Execute the action on target, assuming a rule has been matched and the
+ // recipe for this action has been set. This is the synchrounous executor
+ // implementation (but may still return target_state::busy if the target
+ // is already being executed). Decrements the dependents count.
+ //
+ // Note: does not translate target_state::failed to the failed exception.
+ //
+ target_state
+ execute (action, const target&);
+
+ // As above but wait for completion if the target is busy and translate
+ // target_state::failed to the failed exception.
+ //
+ target_state
+ execute_wait (action, const target&);
+
+ // As above but start asynchronous execution. Return target_state::unknown
+ // if the asynchrounous execution has been started and target_state::busy if
+ // the target has already been busy.
+ //
+ // If fail is false, then return target_state::failed if the target match
+ // failed. Otherwise, throw the failed exception if keep_going is false and
+ // return target_state::failed otherwise.
+ //
+ target_state
+ execute_async (action, const target&,
+ size_t start_count, atomic_count& task_count,
+ bool fail = true);
+
+ // Execute the recipe obtained with match_delegate(). Note that the target's
+ // state is neither checked nor updated by this function. In other words,
+ // the appropriate usage is to call this function from another recipe and to
+ // factor the obtained state into the one returned.
+ //
+ target_state
+ execute_delegate (const recipe&, action, const target&);
+
+ // Execute the inner operation matched with match_inner(). Note that the
+ // returned target state is for the inner operation. The appropriate usage
+ // is to call this function from the outer operation's recipe and to factor
+ // the obtained state into the one returned (similar to how we do it for
+ // prerequisites).
+ //
+ // Note: waits for the completion if the target is busy and translates
+ // target_state::failed to the failed exception.
+ //
+ target_state
+ execute_inner (action, const target&);
+
+ // A special version of the above that should be used for "direct" and "now"
+ // execution, that is, side-stepping the normal target-prerequisite
+ // relationship (so no dependents count is decremented) and execution order
+ // (so this function never returns the postponed target state).
+ //
+ // Note: waits for the completion if the target is busy and translates
+ // target_state::failed to the failed exception.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ execute_direct (action, const target&);
+
+ // The default prerequisite execute implementation. Call execute_async() on
+ // each non-ignored (non-NULL) prerequisite target in a loop and then wait
+ // for their completion. Return target_state::changed if any of them were
+ // changed and target_state::unchanged otherwise. If a prerequisite's
+ // execution is postponed (and thus its state cannot be queried MT-safely)
+ // of if the prerequisite is marked as ad hoc, then set its pointer in
+ // prerequisite_targets to NULL. If count is not 0, then only the first
+ // count prerequisites are executed beginning from start.
+ //
+ // Note that because after the call the ad hoc prerequisites are no longer
+ // easily accessible, this function shouldn't be used in rules that make a
+ // timestamp-based out-of-date'ness determination (which must take into
+ // account such prerequisites). Instead, consider the below versions that
+ // incorporate the timestamp check and do the right thing.
+ //
+ target_state
+ straight_execute_prerequisites (action, const target&,
+ size_t count = 0, size_t start = 0);
+
+ // As above but iterates over the prerequisites in reverse.
+ //
+ target_state
+ reverse_execute_prerequisites (action, const target&, size_t count = 0);
+
+ // Call straight or reverse depending on the current mode.
+ //
+ target_state
+ execute_prerequisites (action, const target&, size_t count = 0);
+
+ // As above but execute prerequisites for the inner action (that have
+ // been matched with match_inner()).
+ //
+ target_state
+ straight_execute_prerequisites_inner (action, const target&,
+ size_t count = 0, size_t start = 0);
+
+ target_state
+ reverse_execute_prerequisites_inner (action, const target&, size_t count = 0);
+
+ target_state
+ execute_prerequisites_inner (action, const target&, size_t count = 0);
+
+ // A version of the above that also determines whether the action needs to
+ // be executed on the target based on the passed timestamp and filter. If
+ // count is not 0, then only the first count prerequisites are executed.
+ //
+ // The filter is passed each prerequisite target and is expected to signal
+ // which ones should be used for timestamp comparison. If the filter is
+ // NULL, then all the prerequisites are used. Note that ad hoc prerequisites
+ // are always used.
+ //
+ // Note that the return value is an optional target state. If the target
+ // needs updating, then the value is absent. Otherwise it is the state that
+ // should be returned. This is used to handle the situation where some
+ // prerequisites were updated but no update of the target is necessary. In
+ // this case we still signal that the target was (conceptually, but not
+ // physically) changed. This is important both to propagate the fact that
+ // some work has been done and to also allow our dependents to detect this
+ // case if they are up to something tricky (like recursively linking liba{}
+ // prerequisites).
+ //
+ // Note that because we use mtime, this function should normally only be
+ // used in the perform_update action (which is straight).
+ //
+ using execute_filter = function<bool (const target&, size_t pos)>;
+
+ optional<target_state>
+ execute_prerequisites (action, const target&,
+ const timestamp&,
+ const execute_filter& = nullptr,
+ size_t count = 0);
+
+ // Another version of the above that does two extra things for the caller:
+ // it determines whether the action needs to be executed on the target based
+ // on the passed timestamp and finds a prerequisite of the specified type
+ // (e.g., a source file). If there are multiple prerequisites of this type,
+ // then the first is returned (this can become important if additional
+ // prerequisites of the same type get injected).
+ //
+ template <typename T>
+ pair<optional<target_state>, const T&>
+ execute_prerequisites (action, const target&,
+ const timestamp&,
+ const execute_filter& = nullptr,
+ size_t count = 0);
+
+ pair<optional<target_state>, const target&>
+ execute_prerequisites (const target_type&,
+ action, const target&,
+ const timestamp&,
+ const execute_filter& = nullptr,
+ size_t count = 0);
+
+ template <typename T>
+ pair<optional<target_state>, const T&>
+ execute_prerequisites (const target_type&,
+ action, const target&,
+ const timestamp&,
+ const execute_filter& = nullptr,
+ size_t count = 0);
+
+ // Execute members of a group or similar prerequisite-like dependencies.
+ // Similar in semantics to execute_prerequisites().
+ //
+ // T can only be const target* or prerequisite_target. If it is the latter,
+ // the ad hoc blank out semantics described in execute_prerequsites() is in
+ // effect.
+ //
+ template <typename T>
+ target_state
+ straight_execute_members (action, atomic_count&, T[], size_t, size_t);
+
+ template <typename T>
+ target_state
+ reverse_execute_members (action, atomic_count&, T[], size_t, size_t);
+
+ template <typename T>
+ inline target_state
+ straight_execute_members (action a, const target& t,
+ T ts[], size_t c, size_t s)
+ {
+ return straight_execute_members (a, t[a].task_count, ts, c, s);
+ }
+
+ template <typename T>
+ inline target_state
+ reverse_execute_members (action a, const target& t,
+ T ts[], size_t c, size_t s)
+ {
+ return reverse_execute_members (a, t[a].task_count, ts, c, s);
+ }
+
+ // Call straight or reverse depending on the current mode.
+ //
+ target_state
+ execute_members (action, const target&, const target*[], size_t);
+
+ template <size_t N>
+ inline target_state
+ straight_execute_members (action a, const target& t, const target* (&ts)[N])
+ {
+ return straight_execute_members (a, t, ts, N, 0);
+ }
+
+ template <size_t N>
+ inline target_state
+ reverse_execute_members (action a, const target& t, const target* (&ts)[N])
+ {
+ return reverse_execute_members (a, t, ts, N, N);
+ }
+
+ template <size_t N>
+ inline target_state
+ execute_members (action a, const target& t, const target* (&ts)[N])
+ {
+ return execute_members (a, t, ts, N);
+ }
+
+ // Return noop_recipe instead of using this function directly.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ noop_action (action, const target&);
+
+ // Default action implementation which forwards to the prerequisites.
+ // Use default_recipe instead of using this function directly.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ default_action (action, const target&);
+
+ // Standard perform(clean) action implementation for the file target
+ // (or derived).
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ perform_clean (action, const target&);
+
+ // As above, but also removes the auxiliary dependency database (.d file).
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ perform_clean_depdb (action, const target&);
+
+ // As above but clean the target group. The group should be an mtime_target
+ // and members should be files.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ perform_clean_group (action, const target&);
+
+ // As above but clean both the target group and depdb. The depdb file path
+ // is derived from the first member file path.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ perform_clean_group_depdb (action, const target&);
+
+ // Helper for custom perform(clean) implementations that cleans extra files
+ // and directories (recursively) specified as a list of either absolute
+ // paths or "path derivation directives". The directive string can be NULL,
+ // or empty in which case it is ignored. If the last character in a
+ // directive is '/', then the resulting path is treated as a directory
+ // rather than a file. The directive can start with zero or more '-'
+ // characters which indicate the number of extensions that should be
+ // stripped before the new extension (if any) is added (so if you want to
+ // strip the extension, specify just "-"). For example:
+ //
+ // perform_clean_extra (a, t, {".d", ".dlls/", "-.dll"});
+ //
+ // The extra files/directories are removed first in the specified order
+ // followed by the ad hoc group member, then target itself, and, finally,
+ // the prerequisites in the reverse order.
+ //
+ // You can also clean extra files derived from ad hoc group members that are
+ // "indexed" using using their target types (see add/find_adhoc_member() for
+ // details).
+ //
+ // Note that if the target path is empty then it is assumed "unreal" and is
+ // not cleaned (but its prerequisites/members still are).
+ //
+ using clean_extras = small_vector<const char*, 8>;
+
+ struct clean_adhoc_extra
+ {
+ const target_type& type;
+ clean_extras extras;
+ };
+
+ using clean_adhoc_extras = small_vector<clean_adhoc_extra, 2>;
+
+ LIBBUILD2_SYMEXPORT target_state
+ perform_clean_extra (action, const file&,
+ const clean_extras&,
+ const clean_adhoc_extras& = {});
+
+ inline target_state
+ perform_clean_extra (action a, const file& f,
+ initializer_list<const char*> e)
+ {
+ return perform_clean_extra (a, f, clean_extras (e));
+ }
+
+ // Update/clean a backlink issuing appropriate diagnostics at appropriate
+ // levels depending on the overload and the changed argument.
+ //
+ enum class backlink_mode
+ {
+ link, // Make a symbolic link if possible, hard otherwise.
+ symbolic, // Make a symbolic link.
+ hard, // Make a hard link.
+ copy, // Make a copy.
+ overwrite // Copy over but don't remove on clean (committed gen code).
+ };
+
+ LIBBUILD2_SYMEXPORT void
+ update_backlink (const file& target,
+ const path& link,
+ bool changed,
+ backlink_mode = backlink_mode::link);
+
+ LIBBUILD2_SYMEXPORT void
+ update_backlink (const path& target,
+ const path& link,
+ bool changed,
+ backlink_mode = backlink_mode::link);
+
+ LIBBUILD2_SYMEXPORT void
+ update_backlink (const path& target,
+ const path& link,
+ backlink_mode = backlink_mode::link);
+
+ LIBBUILD2_SYMEXPORT void
+ clean_backlink (const path& link,
+ uint16_t verbosity,
+ backlink_mode = backlink_mode::link);
+}
+
+#include <libbuild2/algorithm.ixx>
+
+#endif // LIBBUILD2_ALGORITHM_HXX