commit ed2872cd3bf6d352f36bbd34529738a60b0b51eb
parent 2d3f09544895b422eeecf89e0d108da8b8fcdfca
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 17 Apr 2019 14:57:02 -0300
'require' returns where module was found
The function 'require' returns the *loader data* as a second result.
For file searchers, this data is the path where they found the module.
Diffstat:
4 files changed, 66 insertions(+), 34 deletions(-)
diff --git a/loadlib.c b/loadlib.c
@@ -576,9 +576,14 @@ static int searcher_Croot (lua_State *L) {
static int searcher_preload (lua_State *L) {
const char *name = luaL_checkstring(L, 1);
lua_getfield(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
- if (lua_getfield(L, -1, name) == LUA_TNIL) /* not found? */
+ if (lua_getfield(L, -1, name) == LUA_TNIL) { /* not found? */
lua_pushfstring(L, "\n\tno field package.preload['%s']", name);
- return 1;
+ return 1;
+ }
+ else {
+ lua_pushliteral(L, ":preload:");
+ return 2;
+ }
}
@@ -620,17 +625,23 @@ static int ll_require (lua_State *L) {
/* else must load package */
lua_pop(L, 1); /* remove 'getfield' result */
findloader(L, name);
- lua_pushstring(L, name); /* pass name as argument to module loader */
- lua_insert(L, -2); /* name is 1st argument (before search data) */
+ lua_rotate(L, -2, 1); /* function <-> loader data */
+ lua_pushvalue(L, 1); /* name is 1st argument to module loader */
+ lua_pushvalue(L, -3); /* loader data is 2nd argument */
+ /* stack: ...; loader data; loader function; mod. name; loader data */
lua_call(L, 2, 1); /* run loader to load module */
+ /* stack: ...; loader data; result from loader */
if (!lua_isnil(L, -1)) /* non-nil return? */
lua_setfield(L, 2, name); /* LOADED[name] = returned value */
+ else
+ lua_pop(L, 1); /* pop nil */
if (lua_getfield(L, 2, name) == LUA_TNIL) { /* module set no value? */
lua_pushboolean(L, 1); /* use true as result */
- lua_pushvalue(L, -1); /* extra copy to be returned */
+ lua_copy(L, -1, -2); /* replace loader result */
lua_setfield(L, 2, name); /* LOADED[name] = true */
}
- return 1;
+ lua_rotate(L, -2, 1); /* loader data <-> module result */
+ return 2; /* return module result and loader data */
}
/* }====================================================== */
diff --git a/lundump.c b/lundump.c
@@ -271,8 +271,8 @@ static void fchecksize (LoadState *S, size_t size, const char *tname) {
#define checksize(S,t) fchecksize(S,sizeof(t),#t)
static void checkHeader (LoadState *S) {
- /* 1st char already checked */
- checkliteral(S, LUA_SIGNATURE + 1, "not a binary chunk");
+ /* skip 1st char (already read and checked) */
+ checkliteral(S, &LUA_SIGNATURE[1], "not a binary chunk");
if (LoadInt(S) != LUAC_VERSION)
error(S, "version mismatch");
if (LoadByte(S) != LUAC_FORMAT)
diff --git a/manual/manual.of b/manual/manual.of
@@ -6408,11 +6408,15 @@ The function starts by looking into the @Lid{package.loaded} table
to determine whether @id{modname} is already loaded.
If it is, then @id{require} returns the value stored
at @T{package.loaded[modname]}.
+(The absence of a second result in this case
+signals that this call did not have to load the module.)
Otherwise, it tries to find a @emph{loader} for the module.
To find a loader,
-@id{require} is guided by the @Lid{package.searchers} sequence.
-By changing this sequence,
+@id{require} is guided by the table @Lid{package.searchers}.
+Each item in this table is a search function,
+that searches for the module in a particular way.
+By changing this table,
we can change how @id{require} looks for a module.
The following explanation is based on the default configuration
for @Lid{package.searchers}.
@@ -6429,9 +6433,14 @@ it tries an @emph{all-in-one} loader @seeF{package.searchers}.
Once a loader is found,
@id{require} calls the loader with two arguments:
-@id{modname} and an extra value dependent on how it got the loader.
-(If the loader came from a file,
-this extra value is the file name.)
+@id{modname} and an extra value,
+a @emph{loader data},
+also returned by the searcher.
+The loader data can be any value useful to the module;
+for the default searchers,
+it indicates where the loader was found.
+(For instance, if the loader came from a file,
+this extra value is the file path.)
If the loader returns any non-nil value,
@id{require} assigns the returned value to @T{package.loaded[modname]}.
If the loader does not return a non-nil value and
@@ -6439,6 +6448,9 @@ has not assigned any value to @T{package.loaded[modname]},
then @id{require} assigns @Rw{true} to this entry.
In any case, @id{require} returns the
final value of @T{package.loaded[modname]}.
+Besides that value, @id{require} also returns as a second result
+the loader data returned by the searcher,
+which indicates how @id{require} found the module.
If there is any error loading or running the module,
or if it cannot find any loader for the module,
@@ -6558,16 +6570,20 @@ table used by @Lid{require}.
@LibEntry{package.searchers|
-A table used by @Lid{require} to control how to load modules.
+A table used by @Lid{require} to control how to find modules.
Each entry in this table is a @def{searcher function}.
When looking for a module,
@Lid{require} calls each of these searchers in ascending order,
with the module name (the argument given to @Lid{require}) as its
sole argument.
-The function can return another function (the module @def{loader})
-plus an extra value that will be passed to that loader,
-or a string explaining why it did not find that module
+If the searcher finds the module,
+it returns another function, the module @def{loader},
+plus an extra value, a @emph{loader data},
+that will be passed to that loader and
+returned as a second result by @Lid{require}.
+If it cannot find the module,
+it returns a string explaining why
(or @nil if it has nothing to say).
Lua initializes this table with four searcher functions.
@@ -6617,9 +6633,9 @@ into one single library,
with each submodule keeping its original open function.
All searchers except the first one (preload) return as the extra value
-the file name where the module was found,
+the file path where the module was found,
as returned by @Lid{package.searchpath}.
-The first searcher returns no extra value.
+The first searcher always returns the string @St{:preload:}.
}
diff --git a/testes/attrib.lua b/testes/attrib.lua
@@ -122,12 +122,13 @@ local oldpath = package.path
package.path = string.gsub("D/?.lua;D/?.lc;D/?;D/??x?;D/L", "D/", DIR)
-local try = function (p, n, r)
+local try = function (p, n, r, ext)
NAME = nil
- local rr = require(p)
+ local rr, x = require(p)
assert(NAME == n)
assert(REQUIRED == p)
assert(rr == r)
+ assert(ext == x)
end
a = require"names"
@@ -143,27 +144,27 @@ assert(package.searchpath("C", package.path) == D"C.lua")
assert(require"C" == 25)
assert(require"C" == 25)
AA = nil
-try('B', 'B.lua', true)
+try('B', 'B.lua', true, "libs/B.lua")
assert(package.loaded.B)
assert(require"B" == true)
assert(package.loaded.A)
assert(require"C" == 25)
package.loaded.A = nil
-try('B', nil, true) -- should not reload package
-try('A', 'A.lua', true)
+try('B', nil, true, nil) -- should not reload package
+try('A', 'A.lua', true, "libs/A.lua")
package.loaded.A = nil
os.remove(D'A.lua')
AA = {}
-try('A', 'A.lc', AA) -- now must find second option
+try('A', 'A.lc', AA, "libs/A.lc") -- now must find second option
assert(package.searchpath("A", package.path) == D"A.lc")
assert(require("A") == AA)
AA = false
-try('K', 'L', false) -- default option
-try('K', 'L', false) -- default option (should reload it)
+try('K', 'L', false, "libs/L") -- default option
+try('K', 'L', false, "libs/L") -- default option (should reload it)
assert(rawget(_G, "_REQUIREDNAME") == nil)
AA = "x"
-try("X", "XXxX", AA)
+try("X", "XXxX", AA, "libs/XXxX")
removefiles(files)
@@ -183,14 +184,16 @@ files = {
createfiles(files, "_ENV = {}\n", "\nreturn _ENV\n")
AA = 0
-local m = assert(require"P1")
+local m, ext = assert(require"P1")
+assert(ext == "libs/P1/init.lua")
assert(AA == 0 and m.AA == 10)
assert(require"P1" == m)
assert(require"P1" == m)
assert(package.searchpath("P1.xuxu", package.path) == D"P1/xuxu.lua")
-m.xuxu = assert(require"P1.xuxu")
+m.xuxu, ext = assert(require"P1.xuxu")
assert(AA == 0 and m.xuxu.AA == 20)
+assert(ext == "libs/P1/xuxu.lua")
assert(require"P1.xuxu" == m.xuxu)
assert(require"P1.xuxu" == m.xuxu)
assert(require"P1" == m and m.AA == 10)
@@ -267,15 +270,17 @@ else
-- test C modules with prefixes in names
package.cpath = DC"?"
- local lib2 = require"lib2-v2"
+ local lib2, ext = require"lib2-v2"
+ assert(string.find(ext, "libs/lib2-v2", 1, true))
-- check correct access to global environment and correct
-- parameters
assert(_ENV.x == "lib2-v2" and _ENV.y == DC"lib2-v2")
assert(lib2.id("x") == "x")
-- test C submodules
- local fs = require"lib1.sub"
+ local fs, ext = require"lib1.sub"
assert(_ENV.x == "lib1.sub" and _ENV.y == DC"lib1")
+ assert(string.find(ext, "libs/lib1", 1, true))
assert(fs.id(45) == 45)
end
@@ -293,10 +298,10 @@ do
return _ENV
end
- local pl = require"pl"
+ local pl, ext = require"pl"
assert(require"pl" == pl)
assert(pl.xuxu(10) == 30)
- assert(pl[1] == "pl" and pl[2] == nil)
+ assert(pl[1] == "pl" and pl[2] == ":preload:" and ext == ":preload:")
package = p
assert(type(package.path) == "string")
