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+// file : libbuild2/target.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_TARGET_HXX
+#define LIBBUILD2_TARGET_HXX
+
+#include <iterator> // tags, etc.
+#include <type_traits> // aligned_storage
+#include <unordered_map>
+
+#include <libbutl/multi-index.mxx> // map_iterator_adapter
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/scope.hxx>
+#include <libbuild2/action.hxx>
+#include <libbuild2/variable.hxx>
+#include <libbuild2/target-key.hxx>
+#include <libbuild2/target-type.hxx>
+#include <libbuild2/target-state.hxx>
+#include <libbuild2/prerequisite.hxx>
+
+#include <libbuild2/export.hxx>
+
+namespace build2
+{
+ class rule;
+ class scope;
+ class target;
+
+ // From <libbuild2/context.hxx>.
+ //
+ LIBBUILD2_SYMEXPORT extern size_t current_on;
+
+ // From <libbuild2/algorithm.hxx>.
+ //
+ const target& search (const target&, const prerequisite&);
+ const target* search_existing (const prerequisite&);
+
+ // Recipe.
+ //
+ // The returned target state is normally changed or unchanged. If there is
+ // an error, then the recipe should throw failed rather than returning (this
+ // is the only exception that a recipe can throw).
+ //
+ // The return value of the recipe is used to update the target state. If it
+ // is target_state::group then the target's state is the group's state.
+ //
+ // The recipe may also return postponed in which case the target state is
+ // assumed to be unchanged (normally this means a prerequisite was postponed
+ // and while the prerequisite will be re-examined via another dependency,
+ // this target is done).
+ //
+ // Note that max size for the "small capture optimization" in std::function
+ // ranges (in pointer sizes) from 0 (GCC prior to 5) to 2 (GCC 5) to 6 (VC
+ // 14.2). With the size ranging (in bytes for 64-bit target) from 32 (GCC)
+ // to 64 (VC).
+ //
+ using recipe_function = target_state (action, const target&);
+ using recipe = function<recipe_function>;
+
+ // Commonly-used recipes. The default recipe executes the action on
+ // all the prerequisites in a loop, skipping ignored. Specifically,
+ // for actions with the "first" execution mode, it calls
+ // execute_prerequisites() while for those with the "last" mode --
+ // reverse_execute_prerequisites(); see <libbuild2/operation.hxx>,
+ // <libbuild2/algorithm.hxx> for details. The group recipe call's the
+ // group's recipe.
+ //
+ LIBBUILD2_SYMEXPORT extern const recipe empty_recipe;
+ LIBBUILD2_SYMEXPORT extern const recipe noop_recipe;
+ LIBBUILD2_SYMEXPORT extern const recipe default_recipe;
+ LIBBUILD2_SYMEXPORT extern const recipe group_recipe;
+
+ // Defined in <libbuild2/algorithm.hxx>.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ noop_action (action, const target&);
+
+ // Defined in <libbuild2/algorithm.hxx>.
+ //
+ LIBBUILD2_SYMEXPORT target_state
+ group_action (action, const target&);
+
+ // A view of target group members.
+ //
+ struct group_view
+ {
+ const target* const* members; // NULL means not yet known.
+ size_t count;
+ };
+
+ // List of prerequisites resolved to targets. Unless additional storage is
+ // needed, it can be used as just vector<const target*> (which is what we
+ // used to have initially).
+ //
+ struct prerequisite_target
+ {
+ using target_type = build2::target;
+
+ prerequisite_target (const target_type* t, bool a = false, uintptr_t d = 0)
+ : target (t), adhoc (a), data (d) {}
+
+ prerequisite_target (const target_type* t, include_type a, uintptr_t d = 0)
+ : prerequisite_target (t, a == include_type::adhoc, d) {}
+
+ operator const target_type*& () {return target;}
+ operator const target_type* () const {return target;}
+ const target_type* operator-> () const {return target;}
+
+ const target_type* target;
+ bool adhoc; // True if include=adhoc.
+ uintptr_t data;
+ };
+ using prerequisite_targets = vector<prerequisite_target>;
+
+ // A rule match is an element of hint_rule_map.
+ //
+ using rule_match = pair<const string, reference_wrapper<const rule>>;
+
+ // Target.
+ //
+ class LIBBUILD2_SYMEXPORT target
+ {
+ optional<string>* ext_; // Reference to value in target_key.
+
+ public:
+ // For targets that are in the src tree of a project we also keep the
+ // corresponding out directory. As a result we may end up with multiple
+ // targets for the same file if we are building multiple configurations of
+ // the same project at once. We do it this way because, in a sense, a
+ // target's out directory is its "configuration" (in terms of variables).
+ // As an example, consider installing the same README file (src) but for
+ // two different project configurations at once. Which installation
+ // directory should we use? The answer depends on which configuration you
+ // ask.
+ //
+ // Empty out directory indicates this target is in the out tree (including
+ // when src == out). We also treat out of project targets as being in the
+ // out tree.
+ //
+ const dir_path dir; // Absolute and normalized.
+ const dir_path out; // Empty or absolute and normalized.
+ const string name;
+
+ const string* ext () const; // Return NULL if not specified.
+ const string& ext (string);
+
+ const dir_path&
+ out_dir () const {return out.empty () ? dir : out;}
+
+ // A target that is not (yet) entered as part of a real dependency
+ // declaration (for example, that is entered as part of a target-specific
+ // variable assignment, dependency extraction, etc) is called implied.
+ //
+ // The implied flag should only be cleared during the load phase via the
+ // MT-safe target_set::insert().
+ //
+ bool implied;
+
+ // Target group to which this target belongs, if any. Note that we assume
+ // that the group and all its members are in the same scope (for example,
+ // in variable lookup). We also don't support nested groups (with an
+ // exception for ad hoc groups; see below).
+ //
+ // The semantics of the interaction between the group and its members and
+ // what it means to, say, update the group, is unspecified and is
+ // determined by the group's type. In particular, a group can be created
+ // out of member types that have no idea they are part of this group
+ // (e.g., cli.cxx{}).
+ //
+ // Normally, however, there are two kinds of groups: "all" and "choice".
+ // In a choice-group, normally one of the members is selected when the
+ // group is mentioned as a prerequisite with, perhaps, an exception for
+ // special rules, like aliases, where it makes more sense to treat such
+ // group prerequisites as a whole. In this case we say that the rule
+ // "semantically recognizes" the group and picks some of its members.
+ //
+ // Updating a choice-group as a whole can mean updating some subset of its
+ // members (e.g., lib{}). Or the group may not support this at all (e.g.,
+ // obj{}).
+ //
+ // In an all-group, when a group is updated, normally all its members are
+ // updates (and usually with a single command), though there could be some
+ // members that are omitted, depending on the configuration (e.g., an
+ // inline file not/being generated). When an all-group is mentioned as a
+ // prerequisite, the rule is usually interested in the individual members
+ // rather than the whole group. For example, a C++ compile rule would like
+ // to "see" the ?xx{} members when it gets a cli.cxx{} group.
+ //
+ // Which brings us to the group iteration mode. The target type contains a
+ // member called see_through that indicates whether the default iteration
+ // mode for the group should be "see through"; that is, whether we see the
+ // members or the group itself. For the iteration support itself, see the
+ // *_prerequisite_members() machinery below.
+ //
+ // In an all-group we usually want the state (and timestamp; see mtime())
+ // for members to come from the group. This is achieved with the special
+ // target_state::group state. You would normally also use the group_recipe
+ // for group members.
+ //
+ // Note that the group-member link-up can happen anywhere between the
+ // member creation and rule matching so reading the group before the
+ // member has been matched can be racy.
+ //
+ const target* group = nullptr;
+
+ // What has been described above is a "explicit" group. That is, there is
+ // a dedicated target type that explicitly serves as a group and there is
+ // an explicit mechanism for discovering the group's members.
+ //
+ // However, sometimes, we may want to create a group on the fly out of a
+ // normal target type. For example, we have the libs{} target type. But
+ // on Windows a shared library consist of (at least) two files: the import
+ // library and the DLL itself. So we somehow need to be able to capture
+ // that. One approach would be to imply the presence of the second file.
+ // However, that means that a lot of generic rules (e.g., clean, install,
+ // etc) will need to know about this special semantics on Windows. Also,
+ // there would be no convenient way to customize things like extensions,
+ // etc (for which we use target-specific variables). In other words, it
+ // would be much easier and more consistent to make these extra files
+ // proper targets.
+ //
+ // So to support this requirement we have "ad hoc" groups. The idea is
+ // that any target can be turned either by a user's declaration in a
+ // buildfile or by the rule that matches it into an ad hoc group by
+ // chaining several targets together.
+ //
+ // Ad hoc groups have a more restricted semantics compared to the normal
+ // groups. In particular:
+ //
+ // - The ad hoc group itself is in a sense its first/primary target.
+ //
+ // - Group member's recipes, if set, should be group_recipe. Normally, a
+ // rule-managed member isn't matched by the rule since all that's
+ // usually needed is to derive its path.
+ //
+ // - Unless declared, members are discovered lazily, they are only known
+ // after the group's rule's apply() call.
+ //
+ // - Only declared members can be used as prerequisites but all can be
+ // used as targets (e.g., to set variables, etc).
+ //
+ // - Members don't have prerequisites.
+ //
+ // - Ad hoc group cannot have sub-groups (of any kind) though an ad hoc
+ // group can be a sub-group of an explicit group.
+ //
+ // - Member variable lookup skips the ad hoc group (since the group is the
+ // first member, this is normally what we want).
+ //
+ // Note that ad hoc groups can be part of explicit groups. In a sense, we
+ // have a two-level grouping: an explicit group with its members each of
+ // which can be an ad hoc group. For example, lib{} contains libs{} which
+ // may have an import stub as its ad hoc member.
+ //
+ // Use add_adhoc_member(), find_adhoc_member() from algorithms to manage
+ // ad hoc members.
+ //
+ const_ptr<target> member = nullptr;
+
+ bool
+ adhoc_group () const
+ {
+ // An ad hoc group can be a member of a normal group.
+ //
+ return member != nullptr &&
+ (group == nullptr || group->member == nullptr);
+ }
+
+ bool
+ adhoc_member () const
+ {
+ return group != nullptr && group->member != nullptr;
+ }
+
+ public:
+ // Normally you should not call this function directly and rather use
+ // resolve_members() from algorithm.hxx.
+ //
+ virtual group_view
+ group_members (action) const;
+
+ // Note that the returned key "tracks" the target (except for the
+ // extension).
+ //
+ target_key
+ key () const;
+
+ // Scoping.
+ //
+ public:
+ // Most qualified scope that contains this target.
+ //
+ const scope&
+ base_scope () const;
+
+ // Root scope of a project that contains this target. Note that
+ // a target can be out of any (known) project root in which case
+ // this function asserts. If you need to detect this situation,
+ // then use base_scope().root_scope() expression instead.
+ //
+ const scope&
+ root_scope () const;
+
+ // Root scope of a strong amalgamation that contains this target.
+ // The same notes as to root_scope() apply.
+ //
+ const scope&
+ strong_scope () const {return *root_scope ().strong_scope ();}
+
+ // Root scope of the outermost amalgamation that contains this target.
+ // The same notes as to root_scope() apply.
+ //
+ const scope&
+ weak_scope () const {return *root_scope ().weak_scope ();}
+
+ bool
+ in (const scope& s) const
+ {
+ return out_dir ().sub (s.out_path ());
+ }
+
+ // Prerequisites.
+ //
+ // We use an atomic-empty semantics that allows one to "swap in" a set of
+ // prerequisites if none were specified. This is used to implement
+ // "synthesized" dependencies.
+ //
+ public:
+ using prerequisites_type = build2::prerequisites;
+
+ const prerequisites_type&
+ prerequisites () const;
+
+ // Swap-in a list of prerequisites. Return false if unsuccessful (i.e.,
+ // someone beat us to it). Note that it can be called on const target.
+ //
+ bool
+ prerequisites (prerequisites_type&&) const;
+
+ // Check if there are any prerequisites. Note that the group version may
+ // be racy (see target::group).
+ //
+ bool
+ has_prerequisites () const;
+
+ bool
+ has_group_prerequisites () const;
+
+ private:
+ friend class parser;
+
+ // Note that the state is also used to synchronize the prerequisites
+ // value so we use the release-acquire ordering.
+ //
+ // 0 - absent
+ // 1 - being set
+ // 2 - present
+ //
+ atomic<uint8_t> prerequisites_state_ {0};
+ prerequisites_type prerequisites_;
+
+ static const prerequisites_type empty_prerequisites_;
+
+ // Target-specific variables.
+ //
+ // See also rule-specific variables below.
+ //
+ public:
+ variable_map vars;
+
+ // Lookup, including in groups to which this target belongs and then in
+ // outer scopes (including target type/pattern-specific variables). If you
+ // only want to lookup in this target, do it on the variable map directly
+ // (and note that there will be no overrides).
+ //
+ lookup
+ operator[] (const variable& var) const
+ {
+ return find (var).first;
+ }
+
+ lookup
+ operator[] (const variable* var) const // For cached variables.
+ {
+ assert (var != nullptr);
+ return operator[] (*var);
+ }
+
+ lookup
+ operator[] (const string& name) const
+ {
+ const variable* var (var_pool.find (name));
+ return var != nullptr ? operator[] (*var) : lookup ();
+ }
+
+ // As above but also return the depth at which the value is found. The
+ // depth is calculated by adding 1 for each test performed. So a value
+ // that is from the target will have depth 1. That from the group -- 2.
+ // From the innermost scope's target type/patter-specific variables --
+ // 3. From the innermost scope's variables -- 4. And so on. The idea is
+ // that given two lookups from the same target, we can say which one came
+ // earlier. If no value is found, then the depth is set to ~0.
+ //
+ pair<lookup, size_t>
+ find (const variable& var) const
+ {
+ auto p (find_original (var));
+ return var.overrides == nullptr
+ ? p
+ : base_scope ().find_override (var, move (p), true);
+ }
+
+ // If target_only is true, then only look in target and its target group
+ // without continuing in scopes.
+ //
+ pair<lookup, size_t>
+ find_original (const variable&, bool target_only = false) const;
+
+ // Return a value suitable for assignment. See scope for details.
+ //
+ value&
+ assign (const variable& var) {return vars.assign (var);}
+
+ value&
+ assign (const variable* var) {return vars.assign (var);} // For cached.
+
+ // Return a value suitable for appending. See scope for details.
+ //
+ value&
+ append (const variable&);
+
+ // Target operation state.
+ //
+ public:
+ // Atomic task count that is used during match and execution to track the
+ // target's "meta-state" as well as the number of its sub-tasks (e.g.,
+ // busy+1, busy+2, and so on, for instance, number of prerequisites
+ // being matched or executed).
+ //
+ // For each operation in a meta-operation batch (current_on) we have a
+ // "band" of counts, [touched, executed], that represent the target
+ // meta-state. Once the next operation is started, this band "moves" thus
+ // automatically resetting the target to "not yet touched" state for this
+ // operation.
+ //
+ // The target is said to be synchronized (in this thread) if we have
+ // either observed the task count to reach applied or executed or we have
+ // successfully changed it (via compare_exchange) to locked or busy. If
+ // the target is synchronized, then we can access and modify (second case)
+ // its state etc.
+ //
+ static const size_t offset_touched = 1; // Target has been locked.
+ static const size_t offset_tried = 2; // Rule match has been tried.
+ static const size_t offset_matched = 3; // Rule has been matched.
+ static const size_t offset_applied = 4; // Rule has been applied.
+ static const size_t offset_executed = 5; // Recipe has been executed.
+ static const size_t offset_busy = 6; // Match/execute in progress.
+
+ static size_t count_base () {return 5 * (current_on - 1);}
+
+ static size_t count_touched () {return offset_touched + count_base ();}
+ static size_t count_tried () {return offset_tried + count_base ();}
+ static size_t count_matched () {return offset_matched + count_base ();}
+ static size_t count_applied () {return offset_applied + count_base ();}
+ static size_t count_executed () {return offset_executed + count_base ();}
+ static size_t count_busy () {return offset_busy + count_base ();}
+
+ // Inner/outer operation state. See operation.hxx for details.
+ //
+ class LIBBUILD2_SYMEXPORT opstate
+ {
+ public:
+ mutable atomic_count task_count {0}; // Start offset_touched - 1.
+
+ // Number of direct targets that depend on this target in the current
+ // operation. It is incremented during match and then decremented during
+ // execution, before running the recipe. As a result, the recipe can
+ // detect the last chance (i.e., last dependent) to execute the command
+ // (see also the first/last execution modes in <operation.hxx>).
+ //
+ mutable atomic_count dependents {0};
+
+ // Matched rule (pointer to hint_rule_map element). Note that in case of
+ // a direct recipe assignment we may not have a rule (NULL).
+ //
+ const rule_match* rule;
+
+ // Applied recipe.
+ //
+ build2::recipe recipe;
+
+ // Target state for this operation. Note that it is undetermined until
+ // a rule is matched and recipe applied (see set_recipe()).
+ //
+ target_state state;
+
+ // Rule-specific variables.
+ //
+ // The rule (for this action) has to be matched before these variables
+ // can be accessed and only the rule being matched can modify them (so
+ // no iffy modifications of the group's variables by member's rules).
+ //
+ // They are also automatically cleared before another rule is matched,
+ // similar to the data pad. In other words, rule-specific variables are
+ // only valid for this match-execute phase.
+ //
+ variable_map vars;
+
+ // Lookup, continuing in the target-specific variables, etc. Note that
+ // the group's rule-specific variables are not included. If you only
+ // want to lookup in this target, do it on the variable map directly
+ // (and note that there will be no overrides).
+ //
+ lookup
+ operator[] (const variable& var) const
+ {
+ return find (var).first;
+ }
+
+ lookup
+ operator[] (const variable* var) const // For cached variables.
+ {
+ assert (var != nullptr);
+ return operator[] (*var);
+ }
+
+ lookup
+ operator[] (const string& name) const
+ {
+ const variable* var (var_pool.find (name));
+ return var != nullptr ? operator[] (*var) : lookup ();
+ }
+
+ // As above but also return the depth at which the value is found. The
+ // depth is calculated by adding 1 for each test performed. So a value
+ // that is from the rule will have depth 1. That from the target - 2,
+ // and so on, similar to target-specific variables.
+ //
+ pair<lookup, size_t>
+ find (const variable& var) const
+ {
+ auto p (find_original (var));
+ return var.overrides == nullptr
+ ? p
+ : target_->base_scope ().find_override (var, move (p), true, true);
+ }
+
+ // If target_only is true, then only look in target and its target group
+ // without continuing in scopes.
+ //
+ pair<lookup, size_t>
+ find_original (const variable&, bool target_only = false) const;
+
+ // Return a value suitable for assignment. See target for details.
+ //
+ value&
+ assign (const variable& var) {return vars.assign (var);}
+
+ value&
+ assign (const variable* var) {return vars.assign (var);} // For cached.
+
+ public:
+ opstate (): vars (false /* global */) {}
+
+ private:
+ friend class target_set;
+
+ const target* target_ = nullptr; // Back-pointer, set by target_set.
+ };
+
+ action_state<opstate> state;
+
+ opstate& operator[] (action a) {return state[a];}
+ const opstate& operator[] (action a) const {return state[a];}
+
+ // This function should only be called during match if we have observed
+ // (synchronization-wise) that this target has been matched (i.e., the
+ // rule has been applied) for this action.
+ //
+ target_state
+ matched_state (action, bool fail = true) const;
+
+ // See try_match().
+ //
+ pair<bool, target_state>
+ try_matched_state (action, bool fail = true) const;
+
+ // After the target has been matched and synchronized, check if the target
+ // is known to be unchanged. Used for optimizations during search & match.
+ //
+ bool
+ unchanged (action) const;
+
+ // This function should only be called during execution if we have
+ // observed (synchronization-wise) that this target has been executed.
+ //
+ target_state
+ executed_state (action, bool fail = true) const;
+
+ protected:
+ // Version that should be used during match after the target has been
+ // matched for this action.
+ //
+ // Indicate whether there is a rule match with the first half of the
+ // result (see try_match()).
+ //
+ pair<bool, target_state>
+ matched_state_impl (action) const;
+
+ // Return fail-untranslated (but group-translated) state assuming the
+ // target is executed and synchronized.
+ //
+ target_state
+ executed_state_impl (action) const;
+
+ // Return true if the state comes from the group. Target must be at least
+ // matched.
+ //
+ bool
+ group_state (action) const;
+
+ public:
+ // Targets to which prerequisites resolve for this action. Note that
+ // unlike prerequisite::target, these can be resolved to group members.
+ // NULL means the target should be skipped (or the rule may simply not add
+ // such a target to the list).
+ //
+ // Note also that it is possible the target can vary from action to
+ // action, just like recipes. We don't need to keep track of the action
+ // here since the targets will be updated if the recipe is updated,
+ // normally as part of rule::apply().
+ //
+ // Note that the recipe may modify this list.
+ //
+ mutable action_state<build2::prerequisite_targets> prerequisite_targets;
+
+ // Auxilary data storage.
+ //
+ // A rule that matches (i.e., returns true from its match() function) may
+ // use this pad to pass data between its match and apply functions as well
+ // as the recipe. After the recipe is executed, the data is destroyed by
+ // calling data_dtor (if not NULL). The rule should static assert that the
+ // size of the pad is sufficient for its needs.
+ //
+ // Note also that normally at least 2 extra pointers may be stored without
+ // a dynamic allocation in the returned recipe (small object optimization
+ // in std::function). So if you need to pass data only between apply() and
+ // the recipe, then this might be a more convenient way.
+ //
+ // Note also that a rule that delegates to another rule may not be able to
+ // use this mechanism fully since the delegated-to rule may also need the
+ // data pad.
+ //
+ // Currenly the data is not destroyed until the next match.
+ //
+ // Note that the recipe may modify the data. Currently reserved for the
+ // inner part of the action.
+ //
+ static constexpr size_t data_size = sizeof (string) * 16;
+ mutable std::aligned_storage<data_size>::type data_pad;
+
+ mutable void (*data_dtor) (void*) = nullptr;
+
+ template <typename R,
+ typename T = typename std::remove_cv<
+ typename std::remove_reference<R>::type>::type>
+ typename std::enable_if<std::is_trivially_destructible<T>::value,T&>::type
+ data (R&& d) const
+ {
+ assert (sizeof (T) <= data_size && data_dtor == nullptr);
+ return *new (&data_pad) T (forward<R> (d));
+ }
+
+ template <typename R,
+ typename T = typename std::remove_cv<
+ typename std::remove_reference<R>::type>::type>
+ typename std::enable_if<!std::is_trivially_destructible<T>::value,T&>::type
+ data (R&& d) const
+ {
+ assert (sizeof (T) <= data_size && data_dtor == nullptr);
+ T& r (*new (&data_pad) T (forward<R> (d)));
+ data_dtor = [] (void* p) {static_cast<T*> (p)->~T ();};
+ return r;
+ }
+
+ template <typename T>
+ T&
+ data () const {return *reinterpret_cast<T*> (&data_pad);}
+
+ void
+ clear_data () const
+ {
+ if (data_dtor != nullptr)
+ {
+ data_dtor (&data_pad);
+ data_dtor = nullptr;
+ }
+ }
+
+ // Target type info and casting.
+ //
+ public:
+ const target*
+ is_a (const target_type& tt) const {
+ return type ().is_a (tt) ? this : nullptr;}
+
+ template <typename T>
+ T*
+ is_a () {return dynamic_cast<T*> (this);}
+
+ template <typename T>
+ const T*
+ is_a () const {return dynamic_cast<const T*> (this);}
+
+ // Unchecked cast.
+ //
+ template <typename T>
+ T&
+ as () {return static_cast<T&> (*this);}
+
+ template <typename T>
+ const T&
+ as () const {return static_cast<const T&> (*this);}
+
+ // Dynamic derivation to support define.
+ //
+ const target_type* derived_type = nullptr;
+
+ const target_type&
+ type () const
+ {
+ return derived_type != nullptr ? *derived_type : dynamic_type ();
+ }
+
+ virtual const target_type& dynamic_type () const = 0;
+ static const target_type static_type;
+
+ public:
+ // Split the name leaf into target name (in place) and extension
+ // (returned).
+ //
+ static optional<string>
+ split_name (string&, const location&);
+
+ // Combine the target name and extension into the name leaf.
+ //
+ // If the target type has the default extension, then "escape" the
+ // existing extension if any.
+ //
+ static void
+ combine_name (string&, const optional<string>&, bool default_extension);
+
+ // Targets should be created via the targets set below.
+ //
+ public:
+ target (dir_path d, dir_path o, string n)
+ : dir (move (d)), out (move (o)), name (move (n)),
+ vars (false /* global */) {}
+
+ target (target&&) = delete;
+ target& operator= (target&&) = delete;
+
+ target (const target&) = delete;
+ target& operator= (const target&) = delete;
+
+ virtual
+ ~target ();
+
+ friend class target_set;
+ };
+
+ // All targets are from the targets set below.
+ //
+ inline bool
+ operator== (const target& x, const target& y) {return &x == &y;}
+
+ inline bool
+ operator!= (const target& x, const target& y) {return !(x == y);}
+
+ ostream&
+ operator<< (ostream&, const target&);
+
+ // Sometimes it is handy to "mark" a pointer to a target (for example, in
+ // prerequisite_targets). We use the last 2 bits in a pointer for that (aka
+ // the "bit stealing" technique). Note that the pointer needs to be unmarked
+ // before it can be usable so care must be taken in the face of exceptions,
+ // etc.
+ //
+ void
+ mark (const target*&, uint8_t = 1);
+
+ uint8_t
+ marked (const target*); // Can be used as a predicate or to get the mark.
+
+ uint8_t
+ unmark (const target*&);
+
+ // A "range" that presents the prerequisites of a group and one of
+ // its members as one continuous sequence, or, in other words, as
+ // if they were in a single container. The group's prerequisites
+ // come first followed by the member's. If you need to see them
+ // in the other direction, iterate in reverse, for example:
+ //
+ // for (prerequisite& p: group_prerequisites (t))
+ //
+ // for (prerequisite& p: reverse_iterate (group_prerequisites (t))
+ //
+ // Note that in this case the individual elements of each list will
+ // also be traversed in reverse, but that's what you usually want,
+ // anyway.
+ //
+ // Note that you either should be iterating over a locked target (e.g., in
+ // rule's match() or apply()) or you should call resolve_group().
+ //
+ class group_prerequisites
+ {
+ public:
+ explicit
+ group_prerequisites (const target& t);
+
+ group_prerequisites (const target& t, const target* g);
+
+ using prerequisites_type = target::prerequisites_type;
+ using base_iterator = prerequisites_type::const_iterator;
+
+ struct iterator
+ {
+ using value_type = base_iterator::value_type;
+ using pointer = base_iterator::pointer;
+ using reference = base_iterator::reference;
+ using difference_type = base_iterator::difference_type;
+ using iterator_category = std::bidirectional_iterator_tag;
+
+ iterator () {}
+ iterator (const target* t,
+ const target* g,
+ const prerequisites_type* c,
+ base_iterator i): t_ (t), g_ (g), c_ (c), i_ (i) {}
+
+ iterator&
+ operator++ ();
+
+ iterator
+ operator++ (int) {iterator r (*this); operator++ (); return r;}
+
+ iterator&
+ operator-- ();
+
+ iterator
+ operator-- (int) {iterator r (*this); operator-- (); return r;}
+
+ reference operator* () const {return *i_;}
+ pointer operator-> () const {return i_.operator -> ();}
+
+ friend bool
+ operator== (const iterator& x, const iterator& y)
+ {
+ return x.t_ == y.t_ && x.g_ == y.g_ && x.c_ == y.c_ && x.i_ == y.i_;
+ }
+
+ friend bool
+ operator!= (const iterator& x, const iterator& y) {return !(x == y);}
+
+ private:
+ const target* t_ = nullptr;
+ const target* g_ = nullptr;
+ const prerequisites_type* c_ = nullptr;
+ base_iterator i_;
+ };
+
+ using reverse_iterator = std::reverse_iterator<iterator>;
+
+ iterator
+ begin () const;
+
+ iterator
+ end () const;
+
+ reverse_iterator
+ rbegin () const {return reverse_iterator (end ());}
+
+ reverse_iterator
+ rend () const {return reverse_iterator (begin ());}
+
+ size_t
+ size () const;
+
+ private:
+ const target& t_;
+ const target* g_;
+ };
+
+ // A member of a prerequisite. If 'member' is NULL, then this is the
+ // prerequisite itself. Otherwise, it is its member. In this case
+ // 'prerequisite' still refers to the prerequisite.
+ //
+ struct prerequisite_member
+ {
+ using scope_type = build2::scope;
+ using target_type = build2::target;
+ using prerequisite_type = build2::prerequisite;
+ using target_type_type = build2::target_type;
+
+ const prerequisite_type& prerequisite;
+ const target_type* member;
+
+ template <typename T>
+ bool
+ is_a () const
+ {
+ return member != nullptr
+ ? member->is_a<T> () != nullptr
+ : prerequisite.is_a<T> ();
+ }
+
+ bool
+ is_a (const target_type_type& tt) const
+ {
+ return member != nullptr
+ ? member->is_a (tt) != nullptr
+ : prerequisite.is_a (tt);
+ }
+
+ prerequisite_key
+ key () const;
+
+ const target_type_type&
+ type () const
+ {
+ return member != nullptr ? member->type () : prerequisite.type;
+ }
+
+ const string&
+ name () const
+ {
+ return member != nullptr ? member->name : prerequisite.name;
+ }
+
+ const dir_path&
+ dir () const
+ {
+ return member != nullptr ? member->dir : prerequisite.dir;
+ }
+
+ const optional<project_name>&
+ proj () const
+ {
+ // Member cannot be project-qualified.
+ //
+ return member != nullptr ? nullopt_project_name : prerequisite.proj;
+ }
+
+ const scope_type&
+ scope () const
+ {
+ return member != nullptr ? member->base_scope () : prerequisite.scope;
+ }
+
+ const target_type&
+ search (const target_type& t) const
+ {
+ return member != nullptr ? *member : build2::search (t, prerequisite);
+ }
+
+ const target_type*
+ search_existing () const
+ {
+ return member != nullptr
+ ? member
+ : build2::search_existing (prerequisite);
+ }
+
+ const target_type*
+ load (memory_order mo = memory_order_consume)
+ {
+ return member != nullptr ? member : prerequisite.target.load (mo);
+ }
+
+ // Return as a new prerequisite instance.
+ //
+ prerequisite_type
+ as_prerequisite () const;
+ };
+
+ // It is often stored as the target's auxiliary data so make sure there is
+ // no destructor overhead.
+ //
+ static_assert (std::is_trivially_destructible<prerequisite_member>::value,
+ "prerequisite_member is not trivially destructible");
+
+ inline ostream&
+ operator<< (ostream& os, const prerequisite_member& pm)
+ {
+ return os << pm.key ();
+ }
+
+ inline include_type
+ include (action a, const target& t, const prerequisite_member& pm)
+ {
+ return include (a, t, pm.prerequisite, pm.member);
+ }
+
+ // A "range" that presents a sequence of prerequisites (e.g., from
+ // group_prerequisites()) as a sequence of prerequisite_member's. For each
+ // group prerequisite you will "see" either the prerequisite itself or all
+ // its members, depending on the default iteration mode of the target group
+ // type (ad hoc groups are never implicitly see through since one can only
+ // safely access members after a synchronous match). You can skip the
+ // rest of the group members with leave_group() and you can force iteration
+ // over the members with enter_group(). Usage:
+ //
+ // for (prerequisite_member pm: prerequisite_members (a, ...))
+ //
+ // Where ... can be:
+ //
+ // t.prerequisites
+ // reverse_iterate(t.prerequisites)
+ // group_prerequisites (t)
+ // reverse_iterate (group_prerequisites (t))
+ //
+ // But use shortcuts instead:
+ //
+ // prerequisite_members (a, t)
+ // reverse_prerequisite_members (a, t)
+ // group_prerequisite_members (a, t)
+ // reverse_group_prerequisite_members (a, t)
+ //
+ template <typename R>
+ class prerequisite_members_range;
+
+ // See-through group members iteration mode. Ad hoc members must always
+ // be entered explicitly.
+ //
+ enum class members_mode
+ {
+ always, // Iterate over members, assert if not resolvable.
+ maybe, // Iterate over members if resolvable, group otherwise.
+ never // Iterate over group (can still use enter_group()).
+ };
+
+ template <typename R>
+ inline prerequisite_members_range<R>
+ prerequisite_members (action a, const target& t,
+ R&& r,
+ members_mode m = members_mode::always)
+ {
+ return prerequisite_members_range<R> (a, t, forward<R> (r), m);
+ }
+
+ template <typename R>
+ class prerequisite_members_range
+ {
+ public:
+ prerequisite_members_range (action a, const target& t,
+ R&& r,
+ members_mode m)
+ : a_ (a), t_ (t), mode_ (m), r_ (forward<R> (r)), e_ (r_.end ()) {}
+
+ using base_iterator = decltype (declval<R> ().begin ());
+
+ struct iterator
+ {
+ using value_type = prerequisite_member;
+ using pointer = const value_type*;
+ using reference = const value_type&;
+ using difference_type = typename base_iterator::difference_type;
+ using iterator_category = std::forward_iterator_tag;
+
+ iterator (): r_ (nullptr) {}
+ iterator (const prerequisite_members_range* r, const base_iterator& i)
+ : r_ (r), i_ (i), g_ {nullptr, 0}, k_ (nullptr)
+ {
+ if (r_->mode_ != members_mode::never &&
+ i_ != r_->e_ &&
+ i_->type.see_through)
+ switch_mode ();
+ }
+
+ iterator& operator++ ();
+ iterator operator++ (int) {iterator r (*this); operator++ (); return r;}
+
+ // Skip iterating over the rest of this group's members, if any. Note
+ // that the only valid operation after this call is to increment the
+ // iterator.
+ //
+ void
+ leave_group ();
+
+ // Iterate over this group's members. Return false if the member
+ // information is not available. Similar to leave_group(), you should
+ // increment the iterator after calling this function (provided it
+ // returned true).
+ //
+ bool
+ enter_group ();
+
+ // Return true if the next element is this group's members. Normally
+ // used to iterate over group members only, for example:
+ //
+ // for (...; ++i)
+ // {
+ // if (i->prerequisite.type.see_through)
+ // {
+ // for (i.enter_group (); i.group (); )
+ // {
+ // ++i;
+ // ...
+ // }
+ // }
+ // }
+ //
+ bool
+ group () const;
+
+ value_type operator* () const
+ {
+ const target* t (k_ != nullptr ? k_:
+ g_.count != 0 ? g_.members[j_ - 1] : nullptr);
+
+ return value_type {*i_, t};
+ }
+
+ pointer operator-> () const
+ {
+ static_assert (
+ std::is_trivially_destructible<value_type>::value,
+ "prerequisite_member is not trivially destructible");
+
+ const target* t (k_ != nullptr ? k_:
+ g_.count != 0 ? g_.members[j_ - 1] : nullptr);
+
+ return new (&m_) value_type {*i_, t};
+ }
+
+ friend bool
+ operator== (const iterator& x, const iterator& y)
+ {
+ return x.i_ == y.i_ &&
+ x.g_.count == y.g_.count &&
+ (x.g_.count == 0 || x.j_ == y.j_) &&
+ x.k_ == y.k_;
+ }
+
+ friend bool
+ operator!= (const iterator& x, const iterator& y) {return !(x == y);}
+
+ // What we have here is a state for three nested iteration modes (and
+ // no, I am not proud of it). The innermost mode is iteration over an ad
+ // hoc group (k_). Then we have iteration over a normal group (g_ and
+ // j_). Finally, at the outer level, we have the range itself (i_).
+ //
+ // Also, the enter/leave group support is full of ugly, special cases.
+ //
+ private:
+ void
+ switch_mode ();
+
+ private:
+ const prerequisite_members_range* r_;
+ base_iterator i_;
+ group_view g_;
+ size_t j_; // 1-based index, to support enter_group().
+ const target* k_; // Current member of ad hoc group or NULL.
+ mutable typename std::aligned_storage<sizeof (value_type),
+ alignof (value_type)>::type m_;
+ };
+
+ iterator
+ begin () const {return iterator (this, r_.begin ());}
+
+ iterator
+ end () const {return iterator (this, e_);}
+
+ private:
+ action a_;
+ const target& t_;
+ members_mode mode_;
+ R r_;
+ base_iterator e_;
+ };
+
+ // prerequisite_members(t.prerequisites ())
+ //
+ auto
+ prerequisite_members (action a, const target& t,
+ members_mode m = members_mode::always);
+
+ // prerequisite_members(reverse_iterate(t.prerequisites ()))
+ //
+ auto
+ reverse_prerequisite_members (action a, const target& t,
+ members_mode m = members_mode::always);
+
+ // prerequisite_members(group_prerequisites (t))
+ //
+ inline auto
+ group_prerequisite_members (action a, target& t,
+ members_mode m = members_mode::always)
+ {
+ return prerequisite_members (a, t, group_prerequisites (t), m);
+ }
+
+ inline auto
+ group_prerequisite_members (action a, const target& t,
+ members_mode m = members_mode::always)
+ {
+ return prerequisite_members (a, t, group_prerequisites (t), m);
+ }
+
+ // prerequisite_members(reverse_iterate (group_prerequisites (t)))
+ //
+ inline auto
+ reverse_group_prerequisite_members (action a, target& t,
+ members_mode m = members_mode::always)
+ {
+ return prerequisite_members (
+ a, t, reverse_iterate (group_prerequisites (t)), m);
+ }
+
+ inline auto
+ reverse_group_prerequisite_members (action a, const target& t,
+ members_mode m = members_mode::always)
+ {
+ return prerequisite_members (
+ a, t, reverse_iterate (group_prerequisites (t)), m);
+ }
+
+ // A target with an unspecified extension is considered equal to the one
+ // with the specified one. And when we find a target with an unspecified
+ // extension via a key with the specified one, we update the extension,
+ // essentially modifying the map's key. To make this work we use a hash
+ // map. The key's hash ignores the extension, so the hash will stay stable
+ // across extension updates.
+ //
+ // Note also that once the extension is specified, it becomes immutable.
+ //
+ class LIBBUILD2_SYMEXPORT target_set
+ {
+ public:
+ using map_type = std::unordered_map<target_key, unique_ptr<target>>;
+
+ // Return existing target or NULL.
+ //
+ const target*
+ find (const target_key& k, tracer& trace) const;
+
+ const target*
+ find (const target_type& type,
+ const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ const optional<string>& ext,
+ tracer& trace) const
+ {
+ return find (target_key {&type, &dir, &out, &name, ext}, trace);
+ }
+
+ template <typename T>
+ const T*
+ find (const target_type& type,
+ const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ const optional<string>& ext,
+ tracer& trace) const
+ {
+ return static_cast<const T*> (find (type, dir, out, name, ext, trace));
+ }
+
+ // As above but ignore the extension.
+ //
+ const target*
+ find (const target_type& type,
+ const dir_path& dir,
+ const dir_path& out,
+ const string& name) const
+ {
+ slock l (mutex_);
+ auto i (map_.find (target_key {&type, &dir, &out, &name, nullopt}));
+ return i != map_.end () ? i->second.get () : nullptr;
+ }
+
+ template <typename T>
+ const T*
+ find (const dir_path& dir, const dir_path& out, const string& name) const
+ {
+ return static_cast<const T*> (find (T::static_type, dir, out, name));
+ }
+
+ // If the target was inserted, keep the map exclusive-locked and return
+ // the lock. In this case, the target is effectively still being created
+ // since nobody can see it until the lock is released.
+ //
+ pair<target&, ulock>
+ insert_locked (const target_type&,
+ dir_path dir,
+ dir_path out,
+ string name,
+ optional<string> ext,
+ bool implied,
+ tracer&);
+
+ pair<target&, bool>
+ insert (const target_type& tt,
+ dir_path dir,
+ dir_path out,
+ string name,
+ optional<string> ext,
+ bool implied,
+ tracer& t)
+ {
+ auto p (insert_locked (tt,
+ move (dir),
+ move (out),
+ move (name),
+ move (ext),
+ implied,
+ t));
+
+ return pair<target&, bool> (p.first, p.second.owns_lock ());
+ }
+
+ // Note that the following versions always enter implied targets.
+ //
+ template <typename T>
+ T&
+ insert (const target_type& tt,
+ dir_path dir,
+ dir_path out,
+ string name,
+ optional<string> ext,
+ tracer& t)
+ {
+ return insert (tt,
+ move (dir),
+ move (out),
+ move (name),
+ move (ext),
+ true,
+ t).first.template as<T> ();
+ }
+
+ template <typename T>
+ T&
+ insert (const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ const optional<string>& ext,
+ tracer& t)
+ {
+ return insert<T> (T::static_type, dir, out, name, ext, t);
+ }
+
+ template <typename T>
+ T&
+ insert (const dir_path& dir,
+ const dir_path& out,
+ const string& name,
+ tracer& t)
+ {
+ return insert<T> (dir, out, name, nullopt, t);
+ }
+
+ // Note: not MT-safe so can only be used during serial execution.
+ //
+ public:
+ using iterator = butl::map_iterator_adapter<map_type::const_iterator>;
+
+ iterator begin () const {return map_.begin ();}
+ iterator end () const {return map_.end ();}
+
+ void
+ clear () {map_.clear ();}
+
+ private:
+ friend class target; // Access to mutex.
+
+ mutable shared_mutex mutex_;
+ map_type map_;
+ };
+
+ LIBBUILD2_SYMEXPORT extern target_set targets;
+
+ // Modification time-based target.
+ //
+ class LIBBUILD2_SYMEXPORT mtime_target: public target
+ {
+ public:
+ using target::target;
+
+ // Modification time is an "atomic cash". That is, it can be set at any
+ // time (including on a const instance) and we assume everything will be
+ // ok regardless of the order in which racing updates happen because we do
+ // not modify the external state (which is the source of timestemps) while
+ // updating the internal.
+ //
+ // The modification time is reserved for the inner operation thus there is
+ // no action argument.
+ //
+ // The rule for groups that utilize target_state::group is as follows: if
+ // it has any members that are mtime_targets, then the group should be
+ // mtime_target and the members get the mtime from it. During match and
+ // execute the target should be synchronized.
+ //
+ // Note that this function can be called before the target is matched in
+ // which case the value always comes from the target itself. In other
+ // words, that group logic only kicks in once the target is matched.
+ //
+ timestamp
+ mtime () const;
+
+ // Note also that while we can cache the mtime, it may be ignored if the
+ // target state is set to group (see above).
+ //
+ void
+ mtime (timestamp) const;
+
+ // If the mtime is unknown, then load it from the filesystem also caching
+ // the result.
+ //
+ // Note: can only be called during executing and must not be used if the
+ // target state is group.
+ //
+ timestamp
+ load_mtime (const path&) const;
+
+ // Return true if this target is newer than the specified timestamp.
+ //
+ // Note: can only be called during execute on a synchronized target.
+ //
+ bool
+ newer (timestamp) const;
+
+ public:
+ static const target_type static_type;
+
+ protected:
+
+ // Complain if timestamp is not lock-free unless we were told non-lock-
+ // free is ok.
+ //
+#ifndef LIBBUILD2_ATOMIC_NON_LOCK_FREE
+ // C++17:
+ //
+ // static_assert (atomic<timestamp::rep>::is_always_lock_free,
+ // "timestamp is not lock-free on this architecture");
+ //
+#if !defined(ATOMIC_LLONG_LOCK_FREE) || ATOMIC_LLONG_LOCK_FREE != 2
+# error timestamp is not lock-free on this architecture
+#endif
+#endif
+
+ // Note that the value is not used to synchronize any other state so we
+ // use the release-consume ordering (i.e., we are only interested in the
+ // mtime value being synchronized).
+ //
+ // Store it as an underlying representation (normally int64_t) since
+ // timestamp is not usable with atomic (non-noexcept default ctor).
+ //
+ mutable atomic<timestamp::rep> mtime_ {timestamp_unknown_rep};
+ };
+
+ // Filesystem path-based target.
+ //
+ class LIBBUILD2_SYMEXPORT path_target: public mtime_target
+ {
+ public:
+ using mtime_target::mtime_target;
+
+ typedef build2::path path_type;
+
+ // Target path is an "atomic consistent cash". That is, it can be set at
+ // any time (including on a const instance) but any subsequent updates
+ // must set the same path. Or, in other words, once the path is set, it
+ // never changes.
+ //
+ // An empty path may signify special unknown/undetermined/unreal location
+ // (for example, a binless library or an installed import library -- we
+ // know the DLL is there, just not exactly where). In this case you would
+ // also normally set its mtime.
+ //
+ // We used to return a pointer to properly distinguish between not set and
+ // empty but that proved too tedious to work with. So now we return empty
+ // path both when not set (which will be empty_path so you can distinguish
+ // the two case if you really want to) and when set to empty. Note that
+ // this means there could be a race between path and mtime (unless you
+ // lock the target in some other way; see file_rule) so in this case it
+ // makes sense to set the timestamp first.
+ //
+ const path_type&
+ path () const;
+
+ const path_type&
+ path (path_type) const;
+
+ timestamp
+ load_mtime () const;
+
+ // Derive a path from target's dir, name, and, if set, ext. If ext is not
+ // set, try to derive it using the target type extension function and
+ // fallback to default_ext, if specified. In both cases also update the
+ // target's extension (this becomes important if later we need to reliably
+ // determine whether this file has an extension; think hxx{foo.bar.} and
+ // hxx{*}:extension is empty).
+ //
+ // If name_prefix is not NULL, add it before the name part and after the
+ // directory. Similarly, if name_suffix is not NULL, add it after the name
+ // part and before the extension.
+ //
+ // Finally, if the path was already assigned to this target, then this
+ // function verifies that the two are the same.
+ //
+ const path_type&
+ derive_path (const char* default_ext = nullptr,
+ const char* name_prefix = nullptr,
+ const char* name_suffix = nullptr);
+
+ // This version can be used to derive the path from another target's path
+ // by adding another extension.
+ //
+ const path_type&
+ derive_path (path_type base, const char* default_ext = nullptr);
+
+ // As above but only derives (and returns) the extension (empty means no
+ // extension used).
+ //
+ const string&
+ derive_extension (const char* default_ext = nullptr)
+ {
+ return *derive_extension (false, default_ext);
+ }
+
+ // As above but if search is true then look for the extension as if it was
+ // a prerequisite, not a target. In this case, if no extension can be
+ // derived, return NULL instead of failing (like search_existing_file()).
+ //
+ const string*
+ derive_extension (bool search, const char* default_ext = nullptr);
+
+ // Const versions of the above that can be used on unlocked targets. Note
+ // that here we don't allow providing any defaults since you probably
+ // should only use this version if everything comes from the target itself
+ // (and is therefore atomic).
+ //
+ const path_type&
+ derive_path () const
+ {
+ return const_cast<path_target*> (this)->derive_path (); // MT-aware.
+ }
+
+ const string&
+ derive_extension () const
+ {
+ return const_cast<path_target*> (this)->derive_extension (); // MT-aware.
+ }
+
+ public:
+ static const target_type static_type;
+
+ private:
+ // Note that the state is also used to synchronize the path value so
+ // we use the release-acquire ordering.
+ //
+ // 0 - absent
+ // 1 - being set
+ // 2 - present
+ //
+ mutable atomic<uint8_t> path_state_ {0};
+ mutable path_type path_;
+ };
+
+ // File target.
+ //
+ class LIBBUILD2_SYMEXPORT file: public path_target
+ {
+ public:
+ using path_target::path_target;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // Alias target. It represents a list of targets (its prerequisites)
+ // as a single "name".
+ //
+ class LIBBUILD2_SYMEXPORT alias: public target
+ {
+ public:
+ using target::target;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // Directory target. Note that this is not a filesystem directory
+ // but rather an alias target with the directory name. For actual
+ // filesystem directory (creation), see fsdir.
+ //
+ class LIBBUILD2_SYMEXPORT dir: public alias
+ {
+ public:
+ using alias::alias;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+
+ public:
+ template <typename K>
+ static const target*
+ search_implied (const scope&, const K&, tracer&);
+
+ // Return true if the implied buildfile is plausible for the specified
+ // subdirectory of a project with the specified root scope. That is, there
+ // is a buildfile in at least one of its subdirectories. Note that the
+ // directory must exist.
+ //
+ static bool
+ check_implied (const scope& root, const dir_path&);
+
+ private:
+ static prerequisites_type
+ collect_implied (const scope&);
+ };
+
+ // While a filesystem directory is mtime-based, the semantics is not very
+ // useful in our case. In particular, if another target depends on fsdir{},
+ // then all that's desired is the creation of the directory if it doesn't
+ // already exist. In particular, we don't want to update the target just
+ // because some unrelated entry was created in that directory.
+ //
+ class LIBBUILD2_SYMEXPORT fsdir: public target
+ {
+ public:
+ using target::target;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // Executable file.
+ //
+ class LIBBUILD2_SYMEXPORT exe: public file
+ {
+ public:
+ using file::file;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ class LIBBUILD2_SYMEXPORT buildfile: public file
+ {
+ public:
+ using file::file;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // Common documentation file targets.
+ //
+ class LIBBUILD2_SYMEXPORT doc: public file
+ {
+ public:
+ using file::file;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // The problem with man pages is this: different platforms have
+ // different sets of sections. What seems to be the "sane" set
+ // is 1-9 (Linux and BSDs). SysV (e.g., Solaris) instead maps
+ // 8 to 1M (system administration). The section determines two
+ // things: the directory where the page is installed (e.g.,
+ // /usr/share/man/man1) as well as the extension of the file
+ // (e.g., test.1). Note also that there could be sub-sections,
+ // e.g., 1p (for POSIX). Such a page would still go into man1
+ // but will have the .1p extension (at least that's what happens
+ // on Linux). The challenge is to somehow handle this in a
+ // portable manner. So here is the plan:
+ //
+ // First of all, we have the man{} target type which can be used
+ // for a custom man page. That is, you can have any extension and
+ // install it anywhere you please:
+ //
+ // man{foo.X}: install = man/manX
+ //
+ // Then we have man1..9{} target types which model the "sane"
+ // section set and that would be automatically installed into
+ // correct locations on other platforms. In other words, the
+ // idea is that you should be able to have the foo.8 file,
+ // write man8{foo} and have it installed as man1m/foo.1m on
+ // some SysV host.
+ //
+ // Re-mapping the installation directory is easy: to help with
+ // that we have assigned install.man1..9 directory names. The
+ // messy part is to change the extension. It seems the only
+ // way to do that would be to have special logic for man pages
+ // in the generic install rule. @@ This is still a TODO.
+ //
+ // Note that handling subsections with man1..9{} is easy, we
+ // simply specify the extension explicitly, e.g., man{foo.1p}.
+ //
+ class LIBBUILD2_SYMEXPORT man: public doc
+ {
+ public:
+ using doc::doc;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ class LIBBUILD2_SYMEXPORT man1: public man
+ {
+ public:
+ using man::man;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // We derive manifest from doc rather than file so that it get automatically
+ // installed into the same place where the rest of the documentation goes.
+ // If you think about it, it's kind of a documentation, similar to (but
+ // better than) the version file that many projects come with.
+ //
+ class LIBBUILD2_SYMEXPORT manifest: public doc
+ {
+ public:
+ using doc::doc;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+
+ // Common implementation of the target factory, extension, and search
+ // functions.
+ //
+ template <typename T>
+ target*
+ target_factory (const target_type&, dir_path d, dir_path o, string n)
+ {
+ return new T (move (d), move (o), move (n));
+ }
+
+ // Return fixed target extension unless one was specified.
+ //
+ template <const char* ext>
+ const char*
+ target_extension_fix (const target_key&, const scope*);
+
+ template <const char* ext>
+ bool
+ target_pattern_fix (const target_type&, const scope&,
+ string&, optional<string>&, const location&,
+ bool);
+
+ // Get the extension from the variable or use the default if none set. If
+ // the default is NULL, then return NULL.
+ //
+ template <const char* var, const char* def>
+ optional<string>
+ target_extension_var (const target_key&, const scope&, const char*, bool);
+
+ template <const char* var, const char* def>
+ bool
+ target_pattern_var (const target_type&, const scope&,
+ string&, optional<string>&, const location&,
+ bool);
+
+ // Target print functions.
+ //
+
+ // Target type uses the extension but it is fixed and there is no use
+ // printing it (e.g., man1{}).
+ //
+ LIBBUILD2_SYMEXPORT void
+ target_print_0_ext_verb (ostream&, const target_key&);
+
+ // Target type uses the extension and there is normally no default so it
+ // should be printed (e.g., file{}).
+ //
+ LIBBUILD2_SYMEXPORT void
+ target_print_1_ext_verb (ostream&, const target_key&);
+
+ // The default behavior, that is, look for an existing target in the
+ // prerequisite's directory scope.
+ //
+ LIBBUILD2_SYMEXPORT const target*
+ target_search (const target&, const prerequisite_key&);
+
+ // First look for an existing target as above. If not found, then look
+ // for an existing file in the target-type-specific list of paths.
+ //
+ LIBBUILD2_SYMEXPORT const target*
+ file_search (const target&, const prerequisite_key&);
+}
+
+#include <libbuild2/target.ixx>
+#include <libbuild2/target.txx>
+
+#endif // LIBBUILD2_TARGET_HXX