From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 26 Dec 2018 21:45:09 +0300 From: Vladimir Davydov Subject: Re: [PATCH 2/3] Add module to ease using Lua iterators from C Message-ID: <20181226184509.aoreae3ova3k2lz3@esperanza> References: <84dde7baf7a3d9364d3199a6eb705c725589bad0.1544989900.git.alexander.turenko@tarantool.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <84dde7baf7a3d9364d3199a6eb705c725589bad0.1544989900.git.alexander.turenko@tarantool.org> To: Alexander Turenko Cc: tarantool-patches@freelists.org List-ID: On Sun, Dec 16, 2018 at 11:17:25PM +0300, Alexander Turenko wrote: > Needed for #3276. > --- > src/lua/lua_iterator.h | 117 +++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 117 insertions(+) > create mode 100644 src/lua/lua_iterator.h > > diff --git a/src/lua/lua_iterator.h b/src/lua/lua_iterator.h > new file mode 100644 > index 000000000..3e1a88c93 > --- /dev/null > +++ b/src/lua/lua_iterator.h > @@ -0,0 +1,117 @@ > +#ifndef TARANTOOL_LUA_LUA_ITERATOR_H_INCLUDED > +#define TARANTOOL_LUA_LUA_ITERATOR_H_INCLUDED 1 Nit: we don't set an include guard macro to any particular value. > +/* > + * Copyright 2010-2018, Tarantool AUTHORS, please see AUTHORS file. > + * > + * Redistribution and use in source and binary forms, with or > + * without modification, are permitted provided that the following > + * conditions are met: > + * > + * 1. Redistributions of source code must retain the above > + * copyright notice, this list of conditions and the > + * following disclaimer. > + * > + * 2. Redistributions in binary form must reproduce the above > + * copyright notice, this list of conditions and the following > + * disclaimer in the documentation and/or other materials > + * provided with the distribution. > + * > + * THIS SOFTWARE IS PROVIDED BY AUTHORS ``AS IS'' AND > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED > + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR > + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL > + * AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, > + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF > + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR > + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF > + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT > + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF > + * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF > + * SUCH DAMAGE. > + */ > + > +/** > + * This module contains helper functions to interact with a Lua > + * iterator from C. > + */ > + > +#include extern 'C' is missing. > + > +/** > + * Holds iterator state (references to Lua objects). > + */ > +struct lua_iterator { I guess this structure as well as the functions below should have luaL_ prefix. > + int gen; > + int param; > + int state; > +}; > + > +/** > + * Create a Lua iterator from {gen, param, state}. > + */ > +struct lua_iterator * > +lua_iterator_new_fromtable(lua_State *L, int idx) If you include this header into two different source files, you'll get a linker error. All functions defined in a header should be marked static inline. Anyway, I don't think that defining these functions in a header is a good idea - they are heavy and not supposed to be blazing fast. May be, just move them to lua/util.c? > +{ > + struct lua_iterator *it = (struct lua_iterator *) malloc( > + sizeof(struct lua_iterator)); > + > + lua_rawgeti(L, idx, 1); /* Popped by luaL_ref(). */ > + it->gen = luaL_ref(L, LUA_REGISTRYINDEX); > + lua_rawgeti(L, idx, 2); /* Popped by luaL_ref(). */ > + it->param = luaL_ref(L, LUA_REGISTRYINDEX); > + lua_rawgeti(L, idx, 3); /* Popped by luaL_ref(). */ > + it->state = luaL_ref(L, LUA_REGISTRYINDEX); > + > + return it; > +} > + > +/** > + * Move iterator to the next value. Push values returned by > + * gen(param, state) and return its count. Zero means no more > + * results available. > + */ > +int > +lua_iterator_next(lua_State *L, struct lua_iterator *it) > +{ > + int frame_start = lua_gettop(L); > + > + /* Call gen(param, state). */ > + lua_rawgeti(L, LUA_REGISTRYINDEX, it->gen); > + lua_rawgeti(L, LUA_REGISTRYINDEX, it->param); > + lua_rawgeti(L, LUA_REGISTRYINDEX, it->state); > + lua_call(L, 2, LUA_MULTRET); > + int nresults = lua_gettop(L) - frame_start; > + if (nresults == 0) { > + luaL_error(L, "lua_iterator_next: gen(param, state) must " > + "return at least one result"); > + unreachable(); > + return 0; > + } > + > + /* The call above returns nil as the first result. */ > + if (lua_isnil(L, frame_start + 1)) { > + lua_settop(L, frame_start); > + return 0; > + } > + > + /* Save the first result to it->state. */ > + luaL_unref(L, LUA_REGISTRYINDEX, it->state); > + lua_pushvalue(L, frame_start + 1); /* Popped by luaL_ref(). */ > + it->state = luaL_ref(L, LUA_REGISTRYINDEX); > + > + return nresults; > +} > + > +/** > + * Free all resources hold by the iterator. Nit: s/hold/held > + */ > +void lua_iterator_free(lua_State *L, struct lua_iterator *it) > +{ > + luaL_unref(L, LUA_REGISTRYINDEX, it->gen); > + luaL_unref(L, LUA_REGISTRYINDEX, it->param); > + luaL_unref(L, LUA_REGISTRYINDEX, it->state); > + free(it); > +} > + > +#endif /* TARANTOOL_LUA_LUA_ITERATOR_H_INCLUDED */