Replace boost::container::flat_map with a custom flat_map implementat…

…ion in P4Tools. (p4lang#4713)

Signed-off-by: fruffy <[email protected]>

backends/p4tools/common/lib/model.h

@@ -4,15 +4,14 @@
 #include <map>
 #include <utility>
 
-#include "absl/container/btree_map.h"
 #include "ir/ir.h"
 #include "ir/solver.h"
 #include "ir/visitor.h"
 
 namespace P4::P4Tools {
 
 /// Symbolic maps map a state variable to a IR::Expression.
-using SymbolicMapType = absl::btree_map<IR::StateVariable, const IR::Expression *>;
+using SymbolicMapType = P4::flat_map<IR::StateVariable, const IR::Expression *>;
 
 /// Represents a solution found by the solver. A model is a concretized form of a symbolic
 /// environment. All the expressions in a Model must be of type IR::Literal.

ir/solver.h

@@ -4,11 +4,11 @@
 #include <optional>
 #include <vector>
 
-#include "absl/container/btree_map.h"
 #include "ir/compare.h"
 #include "ir/ir.h"
 #include "lib/castable.h"
 #include "lib/cstring.h"
+#include "lib/flat_map.h"
 
 namespace P4 {
 
@@ -18,7 +18,7 @@ using Constraint = IR::Expression;
 
 /// This type maps symbolic variables to their value assigned by the solver.
 using SymbolicMapping =
-    absl::btree_map<const IR::SymbolicVariable *, const IR::Expression *, IR::SymbolicVariableLess>;
+    P4::flat_map<const IR::SymbolicVariable *, const IR::Expression *, IR::SymbolicVariableLess>;
 
 /// Provides a higher-level interface for an SMT solver.
 class AbstractSolver : public ICastable {