refactor(library/blast): hypothesis activation protocol

src/library/blast/backward/backward_strategy.cpp

@@ -52,15 +52,15 @@ static backward_branch_extension & get_extension() {
 class backward_strategy : public strategy {
     virtual optional<expr> preprocess() override { return none_expr(); }
 
-    action_result activate_hypothesis() {
-        optional<hypothesis_idx> hidx = curr_state().activate_hypothesis();
-        if (!hidx) return action_result::failed();
-        trace_action("activate");
+    virtual action_result hypothesis_pre_activation(hypothesis_idx hidx) override {
+        Try(assumption_contradiction_actions(hidx));
+        Try(subst_action(hidx));
+        Try(no_confusion_action(hidx));
+        Try(discard_action(hidx));
+        return action_result::new_branch();
+    }
 
-        Try(assumption_contradiction_actions(*hidx));
-        Try(subst_action(*hidx));
-        Try(no_confusion_action(*hidx));
-        Try(discard_action(*hidx));
+    virtual action_result hypothesis_post_activation(hypothesis_idx hidx) override {
         return action_result::new_branch();
     }
 

src/library/blast/simple_strategy.cpp

@@ -26,28 +26,27 @@ namespace blast {
 /** \brief Implement a simple proof strategy for blast.
     We use it mainly for testing new actions and the whole blast infra-structure. */
 class simple_strategy : public strategy {
-    action_result activate_hypothesis(bool preprocess) {
-        scope_trace scope(!preprocess && get_config().m_trace);
 
-        auto hidx = curr_state().activate_hypothesis();
-        if (!hidx) return action_result::failed();
-        trace_action("activate");
+    action_result hypothesis_pre_activation(hypothesis_idx hidx) override {
+        Try(assumption_contradiction_actions(hidx));
+        Try(simplify_hypothesis_action(hidx));
+        Try(no_confusion_action(hidx));
+        TrySolve(assert_cc_action(hidx));
+        Try(discard_action(hidx));
+        Try(subst_action(hidx));
+        return action_result::new_branch();
+    }
 
-        Try(assumption_contradiction_actions(*hidx));
-        Try(simplify_hypothesis_action(*hidx));
-        TrySolve(assert_cc_action(*hidx));
-        Try(subst_action(*hidx));
-        Try(no_confusion_action(*hidx));
-        Try(discard_action(*hidx));
-        Try(forward_action(*hidx));
-        Try(recursor_preprocess_action(*hidx));
+    action_result hypothesis_post_activation(hypothesis_idx hidx) override {
+        Try(forward_action(hidx));
+        Try(recursor_preprocess_action(hidx));
         return action_result::new_branch();
     }
 
     /* \brief Preprocess state
        It keeps applying intros, activating and finally simplify target.
        Return an expression if the goal has been proved during preprocessing step. */
-    virtual optional<expr> preprocess() {
+    virtual optional<expr> preprocess() override {
         trace("* Preprocess");
         while (true) {
             if (!failed(intros_action()))
@@ -61,7 +60,7 @@ class simple_strategy : public strategy {
         return none_expr();
     }
 
-    virtual action_result next_action() {
+    virtual action_result next_action() override {
         Try(intros_action());
         Try(activate_hypothesis(false));
         Try(trivial_action());

src/library/blast/state.cpp

@@ -765,20 +765,23 @@ void state::remove_from_indices(hypothesis const & h, hypothesis_idx hidx) {
         m_branch.m_head_to_hyps.erase(*i, hidx);
 }
 
-optional<unsigned> state::activate_hypothesis() {
+optional<unsigned> state::select_hypothesis_to_activate() {
     while (true) {
         if (m_branch.m_todo_queue.empty())
             return optional<unsigned>();
         unsigned hidx             = m_branch.m_todo_queue.erase_min();
         hypothesis const & h_decl = get_hypothesis_decl(hidx);
         if (!h_decl.is_dead()) {
-            m_branch.m_active.insert(hidx);
-            update_indices(hidx);
             return optional<unsigned>(hidx);
         }
     }
 }
 
+void state::activate_hypothesis(hypothesis_idx hidx) {
+    m_branch.m_active.insert(hidx);
+    update_indices(hidx);
+}
+
 bool state::hidx_depends_on(unsigned hidx_user, unsigned hidx_provider) const {
     if (auto s = m_branch.m_forward_deps.find(hidx_provider)) {
         return s->contains(hidx_user);

src/library/blast/state.h

@@ -293,8 +293,9 @@ public:
             });
     }
 
-    /** \brief Activate the next hypothesis in the TODO queue, return none if the TODO queue is empty. */
-    optional<hypothesis_idx> activate_hypothesis();
+    /** \brief Select next hypothesis in the TODO queue, return none if the TODO queue is empty. */
+    optional<hypothesis_idx> select_hypothesis_to_activate();
+    void activate_hypothesis(hypothesis_idx hidx);
 
     /** \brief Store in \c r the hypotheses in this branch sorted by dependency depth */
     void get_sorted_hypotheses(hypothesis_idx_buffer & r) const;

src/library/blast/strategy.cpp

@@ -14,6 +14,19 @@ namespace lean {
 namespace blast {
 strategy::strategy() {}
 
+action_result strategy::activate_hypothesis(bool preprocess) {
+    scope_trace scope(!preprocess && get_config().m_trace);
+    auto hidx = curr_state().select_hypothesis_to_activate();
+    if (!hidx) return action_result::failed();
+    auto r    = hypothesis_pre_activation(*hidx);
+    if (!solved(r) && !failed(r)) {
+        curr_state().activate_hypothesis(*hidx);
+        return hypothesis_post_activation(*hidx);
+    } else {
+        return r;
+    }
+}
+
 action_result strategy::next_branch(expr pr) {
     while (curr_state().has_proof_steps()) {
         proof_step s     = curr_state().top_proof_step();

src/library/blast/strategy.h

@@ -24,7 +24,10 @@ class strategy {
 protected:
     virtual optional<expr> preprocess() = 0;
     virtual action_result next_action() = 0;
+    virtual action_result hypothesis_pre_activation(hypothesis_idx hidx) = 0;
+    virtual action_result hypothesis_post_activation(hypothesis_idx hidx) = 0;
 
+    action_result activate_hypothesis(bool preprocess = false);
     action_result next_branch(expr pr);
     optional<expr> search_upto(unsigned depth);
     optional<expr> search();