From 1c5d3295ccf33cebe5d2b2aec2a5dc0c9a7940e4 Mon Sep 17 00:00:00 2001
From: Leonardo de Moura <leonardo@microsoft.com>
Date: Wed, 11 Jun 2014 13:48:28 -0700
Subject: [PATCH] refactor(library/deep_copy): use replace to implement
 deep_copy

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
---
 src/library/deep_copy.cpp | 52 +++++++++------------------------------
 1 file changed, 11 insertions(+), 41 deletions(-)

diff --git a/src/library/deep_copy.cpp b/src/library/deep_copy.cpp
index eb8b7cc9bf..c0c0a1c4a3 100644
--- a/src/library/deep_copy.cpp
+++ b/src/library/deep_copy.cpp
@@ -6,10 +6,11 @@ Author: Leonardo de Moura
 */
 #include "util/buffer.h"
 #include "kernel/expr.h"
-#include "kernel/expr_maps.h"
+#include "kernel/replace_fn.h"
 
 namespace lean {
 expr copy(expr const & a) {
+    scoped_expr_caching scope(false);
     switch (a.kind()) {
     case expr_kind::Var:      return mk_var(var_idx(a));
     case expr_kind::Constant: return mk_constant(const_name(a), const_levels(a));
@@ -25,44 +26,13 @@ expr copy(expr const & a) {
     lean_unreachable(); // LCOV_EXCL_LINE
 }
 
-/** \brief Implements deep copy of kernel expressions. */
-class deep_copy_fn {
-    expr_cell_map<expr> m_cache;
-
-    expr apply(expr const & a) {
-        bool sh = false;
-        if (is_shared(a)) {
-            auto r = m_cache.find(a.raw());
-            if (r != m_cache.end())
-                return r->second;
-            sh = true;
-        }
-        expr r;
-        switch (a.kind()) {
-        case expr_kind::Var:
-        case expr_kind::Constant:
-        case expr_kind::Sort:
-        case expr_kind::Macro:   r = copy(a); break;
-        case expr_kind::App:     r = mk_app(apply(app_fn(a)), apply(app_arg(a))); break;
-        case expr_kind::Lambda:  r = mk_lambda(binding_name(a), apply(binding_domain(a)), apply(binding_body(a))); break;
-        case expr_kind::Pi:      r = mk_pi(binding_name(a), apply(binding_domain(a)), apply(binding_body(a))); break;
-        case expr_kind::Let:     r = mk_let(let_name(a), apply(let_type(a)), apply(let_value(a)), apply(let_body(a))); break;
-        case expr_kind::Meta:    r = mk_metavar(mlocal_name(a), apply(mlocal_type(a))); break;
-        case expr_kind::Local:   r = mk_local(mlocal_name(a), local_pp_name(a), apply(mlocal_type(a))); break;
-        }
-        if (sh)
-            m_cache.insert(std::make_pair(a.raw(), r));
-        return r;
-    }
-public:
-    /**
-        \brief Return a new expression that is equal to the given
-        argument, but does not share any memory cell with it.
-    */
-    expr operator()(expr const & a) {
-        scoped_expr_caching set(false);
-        return apply(a);
-    }
-};
-expr deep_copy(expr const & e) { return deep_copy_fn()(e); }
+expr deep_copy(expr const & e) {
+    scoped_expr_caching scope(false);
+    return replace(e, [](expr const & e, unsigned) {
+            if (is_atomic(e))
+                return some_expr(copy(e));
+            else
+                return none_expr();
+        });
+}
 }