feat(library/app_builder): expose app_builder API in Lua

src/library/app_builder.cpp

@@ -9,6 +9,7 @@ Author: Leonardo de Moura
 #include "kernel/instantiate.h"
 #include "library/match.h"
 #include "library/app_builder.h"
+#include "library/kernel_bindings.h"
 
 namespace lean {
 
@@ -229,4 +230,56 @@ optional<expr> app_builder::mk_app(name const & n, expr const & a1, expr const &
 }
 void app_builder::push() { m_ptr->push(); }
 void app_builder::pop() { m_ptr->pop(); }
+
+struct lua_app_builder {
+    type_checker_ref m_tc;
+    app_builder      m_builder;
+    lua_app_builder(type_checker_ref const & r):m_tc(r), m_builder(*r.get()) {}
+};
+
+typedef std::shared_ptr<lua_app_builder> app_builder_ref;
+
+DECL_UDATA(app_builder_ref)
+
+static int mk_app_builder(lua_State * L) {
+    return push_app_builder_ref(L, std::make_shared<lua_app_builder>(to_type_checker_ref(L, 1)));
+}
+
+static int app_builder_mk_app(lua_State * L) {
+    int nargs = lua_gettop(L);
+    buffer<expr> args;
+    app_builder & b = to_app_builder_ref(L, 1)->m_builder;
+    name n          = to_name_ext(L, 2);
+    for (int i = 3; i <= nargs; i++)
+        args.push_back(to_expr(L, i));
+    return push_optional_expr(L, b.mk_app(n, args.size(), args.data()));
+}
+
+static int app_builder_push(lua_State * L) {
+    to_app_builder_ref(L, 1)->m_builder.push();
+    return 0;
+}
+
+static int app_builder_pop(lua_State * L) {
+    to_app_builder_ref(L, 1)->m_builder.pop();
+    return 0;
+}
+
+static const struct luaL_Reg app_builder_ref_m[] = {
+    {"__gc",    app_builder_ref_gc},
+    {"mk_app",  safe_function<app_builder_mk_app>},
+    {"push",    safe_function<app_builder_push>},
+    {"pop",     safe_function<app_builder_pop>},
+    {0, 0}
+};
+
+void open_app_builder(lua_State * L) {
+    luaL_newmetatable(L, app_builder_ref_mt);
+    lua_pushvalue(L, -1);
+    lua_setfield(L, -2, "__index");
+    setfuncs(L, app_builder_ref_m, 0);
+
+    SET_GLOBAL_FUN(mk_app_builder,       "app_builder");
+    SET_GLOBAL_FUN(app_builder_ref_pred, "is_app_builder");
+}
 }

src/library/app_builder.h

@@ -54,4 +54,6 @@ public:
     */
     void pop();
 };
+
+void open_app_builder(lua_State * L);
 }

src/library/register_module.h

@@ -18,6 +18,7 @@ Author: Leonardo de Moura
 #include "library/scoped_ext.h"
 #include "library/match.h"
 #include "library/reducible.h"
+#include "library/app_builder.h"
 
 namespace lean {
 inline void open_core_module(lua_State * L) {
@@ -33,6 +34,7 @@ inline void open_core_module(lua_State * L) {
     open_explicit(L);
     open_match(L);
     open_reducible(L);
+    open_app_builder(L);
 }
 inline void register_core_module() {
     script_state::register_module(open_core_module);