Independent values can be suggested for concurrent edits

Such that multiple input devices can be used to attempt edits on the same set of variables.
cdglabs · Feb 18, 2015 · 989361f · 989361f
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diff --git a/rhea/simplex_solver.cpp b/rhea/simplex_solver.cpp
@@ -336,6 +336,23 @@ simplex_solver& simplex_solver::suggest_value(const variable& v, double x)
     return *this;
 }
 
+simplex_solver& simplex_solver::suggest_value(const constraint& c, double x)
+{
+    if (!c.is_edit_constraint()) {
+        throw edit_misuse();
+    }
+    auto& e = c.as<edit_constraint>();
+    auto ei = std::find(edit_info_list_.rbegin(), edit_info_list_.rend(), c);
+    if (ei == edit_info_list_.rend())
+        throw edit_misuse(e.var());
+
+    double delta{x - ei->prev_constant};
+    ei->prev_constant = x;
+    delta_edit_constant(delta, ei->plus, ei->minus);
+
+    return *this;
+}
+
 simplex_solver& simplex_solver::suggest(const variable& v, double x)
 {
     add_edit_var(v);

diff --git a/rhea/simplex_solver.hpp b/rhea/simplex_solver.hpp
@@ -82,6 +82,12 @@ class simplex_solver : public solver, public tableau
      *  after resolve() or end_edit() has been called. */
     simplex_solver& suggest_value(const variable& v, double x);
 
+    /** Suggest a new value for an edit constraint.
+     *  The constraint needs to be an edit constraint and needs to
+     *  have been added before.  The tableau will not be solved
+     *  completely until resolve() or end_edit() has been called. */
+    simplex_solver& suggest_value(const constraint& v, double x);
+
     /** Suggest a new value for a variables.
      *  This function calls add_edit_variable(), begin_edit(), and
      *  end_edit() as well.

diff --git a/unit_tests/unit_tests.cpp b/unit_tests/unit_tests.cpp
@@ -995,3 +995,35 @@ BOOST_AUTO_TEST_CASE(contains_constraint)
     solver.remove_constraint(c);
     BOOST_CHECK(!solver.contains_constraint(c));
 }
+
+BOOST_AUTO_TEST_CASE(independent_values_can_be_suggested_for_concurrent_edits)
+{
+    simplex_solver s;
+    variable v;
+    constraint e1 = std::make_shared<edit_constraint>(v);
+    constraint e2 = std::make_shared<edit_constraint>(v, strength::medium());
+
+    s.add_constraint(e1);
+    s.add_constraint(e2);
+
+    s.suggest_value(e1, 42);
+    s.suggest_value(e2, 21);
+    s.resolve();
+    BOOST_CHECK_EQUAL(v.value(), 42);
+
+    // Other edit becomes visible after highest priority one is
+    // removed from the solver
+    s.remove_constraint(e1);
+    BOOST_CHECK_EQUAL(v.value(), 21);
+
+    // Edits are only remembered while the constraint is active
+    s.add_constraint(e1);
+    BOOST_CHECK_EQUAL(v.value(), 21);
+
+    // Multiple edits respect strength changes
+    s.suggest_value(e1, 50);
+    s.resolve();
+    BOOST_CHECK_EQUAL(v.value(), 50);
+    s.change_strength(e1, strength::weak());
+    BOOST_CHECK_EQUAL(v.value(), 21);
+}