[PATCH 1/4] schema: use tuple field names in Lua

[Vladimir Davydov <vdavydov.dev@gmail.com>]

When schema.lua was introduced, there was no such thing as space format
and we had to access tuple fields by no. Now we can use human readable
names. Let's do it - this should improve code readability.

A note about box/alter.test.lua: for some reason it clears format of
_space and _index system spaces, which apparently breaks our assumption
about field names. Let's zap those pointless test cases.
---
 src/box/lua/schema.lua  | 98 ++++++++++++++++++++++++-------------------------
 test/box/alter.result   | 15 --------
 test/box/alter.test.lua |  6 ---
 3 files changed, 49 insertions(+), 70 deletions(-)

diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
index f31cf7f2..036e5f2d 100644
--- a/src/box/lua/schema.lua
+++ b/src/box/lua/schema.lua
@@ -155,7 +155,7 @@ local function user_or_role_resolve(user)
     if tuple == nil then
         return nil
     end
-    return tuple[1]
+    return tuple.id
 end
 
 local function role_resolve(name_or_id)
@@ -166,10 +166,10 @@ local function role_resolve(name_or_id)
     elseif type(name_or_id) ~= 'nil' then
         tuple = _vuser:get{name_or_id}
     end
-    if tuple == nil or tuple[4] ~= 'role' then
+    if tuple == nil or tuple.type ~= 'role' then
         return nil
     else
-        return tuple[1]
+        return tuple.id
     end
 end
 
@@ -181,10 +181,10 @@ local function user_resolve(name_or_id)
     elseif type(name_or_id) ~= 'nil' then
         tuple = _vuser:get{name_or_id}
     end
-    if tuple == nil or tuple[4] ~= 'user' then
+    if tuple == nil or tuple.type ~= 'user' then
         return nil
     else
-        return tuple[1]
+        return tuple.id
     end
 end
 
@@ -197,7 +197,7 @@ local function sequence_resolve(name_or_id)
         tuple = _vsequence:get{name_or_id}
     end
     if tuple ~= nil then
-        return tuple[1], tuple
+        return tuple.id, tuple
     else
         return nil
     end
@@ -209,7 +209,7 @@ local function revoke_object_privs(object_type, object_id)
     local _priv = box.space[box.schema.PRIV_ID]
     local privs = _vpriv.index.object:select{object_type, object_id}
     for k, tuple in pairs(privs) do
-        local uid = tuple[2]
+        local uid = tuple.grantee
         _priv:delete{uid, object_type, object_id}
     end
 end
@@ -453,13 +453,13 @@ box.schema.space.create = function(name, options)
         local _schema = box.space._schema
         local max_id = _schema:update({'max_id'}, {{'+', 2, 1}})
         if max_id == nil then
-            id = _space.index.primary:max()[1]
+            id = _space.index.primary:max().id
             if id < box.schema.SYSTEM_ID_MAX then
                 id = box.schema.SYSTEM_ID_MAX
             end
             max_id = _schema:insert{'max_id', id + 1}
         end
-        id = max_id[2]
+        id = max_id.value
     end
     local uid = session.euid()
     if options.user then
@@ -492,7 +492,7 @@ function box.schema.space.format(id, format)
         if tuple == nil then
             box.error(box.error.NO_SUCH_SPACE, '#' .. tostring(id))
         end
-        return tuple[7]
+        return tuple.format
     else
         check_param(format, 'format', 'table')
         format = update_format(format)
@@ -514,9 +514,9 @@ box.schema.space.drop = function(space_id, space_name, opts)
     local _space_sequence = box.space[box.schema.SPACE_SEQUENCE_ID]
     local _fk_constraint = box.space[box.schema.FK_CONSTRAINT_ID]
     local sequence_tuple = _space_sequence:delete{space_id}
-    if sequence_tuple ~= nil and sequence_tuple[3] == true then
+    if sequence_tuple ~= nil and sequence_tuple.is_generated == true then
         -- Delete automatically generated sequence.
-        box.schema.sequence.drop(sequence_tuple[2])
+        box.schema.sequence.drop(sequence_tuple.sequence_id)
     end
     for _, t in _trigger.index.space_id:pairs({space_id}) do
         _trigger:delete({t.name})
@@ -527,7 +527,7 @@ box.schema.space.drop = function(space_id, space_name, opts)
     local keys = _vindex:select(space_id)
     for i = #keys, 1, -1 do
         local v = keys[i]
-        _index:delete{v[1], v[2]}
+        _index:delete{v.id, v.iid}
     end
     revoke_object_privs('space', space_id)
     _truncate:delete{space_id}
@@ -847,9 +847,9 @@ box.schema.index.create = function(space_id, name, options)
         local tuple = _vindex.index[0]
             :select(space_id, { limit = 1, iterator = 'LE' })[1]
         if tuple then
-            local id = tuple[1]
+            local id = tuple.id
             if id == space_id then
-                iid = tuple[2] + 1
+                iid = tuple.iid + 1
             end
         end
     end
@@ -923,9 +923,9 @@ box.schema.index.drop = function(space_id, index_id)
     if index_id == 0 then
         local _space_sequence = box.space[box.schema.SPACE_SEQUENCE_ID]
         local sequence_tuple = _space_sequence:delete{space_id}
-        if sequence_tuple ~= nil and sequence_tuple[3] == true then
+        if sequence_tuple ~= nil and sequence_tuple.is_generated == true then
             -- Delete automatically generated sequence.
-            box.schema.sequence.drop(sequence_tuple[2])
+            box.schema.sequence.drop(sequence_tuple.sequence_id)
         end
     end
     local _index = box.space[box.schema.INDEX_ID]
@@ -993,25 +993,23 @@ box.schema.index.alter = function(space_id, index_id, options)
     local tuple = _index:get{space_id, index_id }
     local parts = {}
     local index_opts = {}
-    local OPTS = 5
-    local PARTS = 6
-    if type(tuple[OPTS]) == 'number' then
+    if type(tuple.opts) == 'number' then
         -- old format
-        index_opts.unique = tuple[OPTS] == 1
-        local part_count = tuple[PARTS]
+        index_opts.unique = tuple[5] == 1
+        local part_count = tuple[6]
         for i = 1, part_count do
             table.insert(parts, {tuple[2 * i + 4], tuple[2 * i + 5]});
         end
     else
         -- new format
-        index_opts = tuple[OPTS]
-        parts = tuple[PARTS]
+        index_opts = tuple.opts
+        parts = tuple.parts
     end
     if options.name == nil then
-        options.name = tuple[3]
+        options.name = tuple.name
     end
     if options.type == nil then
-        options.type = tuple[4]
+        options.type = tuple.type
     end
     for k, t in pairs(index_options) do
         if options[k] ~= nil then
@@ -1048,7 +1046,7 @@ box.schema.index.alter = function(space_id, index_id, options)
         end
     end
     if sequence == true then
-        if sequence_tuple == nil or sequence_tuple[3] == false then
+        if sequence_tuple == nil or sequence_tuple.is_generated == false then
             sequence = box.schema.sequence.create(space.name .. '_seq')
             sequence = sequence.id
             sequence_is_generated = true
@@ -1070,10 +1068,10 @@ box.schema.index.alter = function(space_id, index_id, options)
     if sequence then
         _space_sequence:replace{space_id, sequence, sequence_is_generated}
     end
-    if sequence_tuple ~= nil and sequence_tuple[3] == true and
-       sequence_tuple[2] ~= sequence then
+    if sequence_tuple ~= nil and sequence_tuple.is_generated == true and
+       sequence_tuple.sequence_id ~= sequence then
         -- Delete automatically generated sequence.
-        box.schema.sequence.drop(sequence_tuple[2])
+        box.schema.sequence.drop(sequence_tuple.sequence_id)
     end
 end
 
@@ -1662,13 +1660,13 @@ end
 
 local function sequence_on_alter(old_tuple, new_tuple)
     if old_tuple and not new_tuple then
-        local old_name = old_tuple[3]
+        local old_name = old_tuple.name
         box.sequence[old_name] = nil
     elseif not old_tuple and new_tuple then
         local seq = sequence_new(new_tuple)
         box.sequence[seq.name] = seq
     else
-        local old_name = old_tuple[3]
+        local old_name = old_tuple.name
         local seq = box.sequence[old_name]
         if not seq then
             seq = sequence_new(seq, new_tuple)
@@ -1919,7 +1917,7 @@ local function object_resolve(object_type, object_name)
             func = _vfunc:get{object_name}
         end
         if func then
-            return func[1]
+            return func.id
         else
             box.error(box.error.NO_SUCH_FUNCTION, object_name)
         end
@@ -1945,8 +1943,8 @@ local function object_resolve(object_type, object_name)
         else
             role_or_user = _vuser:get{object_name}
         end
-        if role_or_user and role_or_user[4] == object_type then
-            return role_or_user[1]
+        if role_or_user and role_or_user.type == object_type then
+            return role_or_user.id
         elseif object_type == 'role' then
             box.error(box.error.NO_SUCH_ROLE, object_name)
         else
@@ -1973,7 +1971,7 @@ local function object_name(object_type, object_id)
     else
         box.error(box.error.UNKNOWN_SCHEMA_OBJECT, object_type)
     end
-    return space:get{object_id}[3]
+    return space:get{object_id}.name
 end
 
 box.schema.func = {}
@@ -2010,7 +2008,7 @@ box.schema.func.drop = function(name, opts)
         tuple = _vfunc:get{name}
     end
     if tuple then
-        fid = tuple[1]
+        fid = tuple.id
     end
     if fid == nil then
         if not opts.if_exists then
@@ -2096,7 +2094,7 @@ end
 box.internal.collation.id_by_name = function(name)
     local _coll = box.space[box.schema.COLLATION_ID]
     local coll = _coll.index.name:get{name}
-    return coll[1]
+    return coll.id
 end
 
 box.schema.user = {}
@@ -2148,7 +2146,7 @@ box.schema.user.create = function(name, opts)
         auth_mech_list["chap-sha1"] = box.schema.user.password(opts.password)
     end
     local _user = box.space[box.schema.USER_ID]
-    uid = _user:auto_increment{session.euid(), name, 'user', auth_mech_list}[1]
+    uid = _user:auto_increment{session.euid(), name, 'user', auth_mech_list}.id
     -- grant role 'public' to the user
     box.schema.user.grant(uid, 'public')
     -- Grant privilege 'alter' on itself, so that it can
@@ -2201,7 +2199,7 @@ local function grant(uid, name, privilege, object_type,
     local tuple = _vpriv:get{uid, object_type, oid}
     local old_privilege
     if tuple ~= nil then
-        old_privilege = tuple[5]
+        old_privilege = tuple.privilege
     else
         old_privilege = 0
     end
@@ -2255,8 +2253,8 @@ local function revoke(uid, name, privilege, object_type, object_name, options)
                       object_type, object_name)
         end
     end
-    local old_privilege = tuple[5]
-    local grantor = tuple[1]
+    local old_privilege = tuple.privilege
+    local grantor = tuple.grantor
     -- sic:
     -- a user may revoke more than he/she granted
     -- (erroneous user input)
@@ -2282,25 +2280,25 @@ local function drop(uid, opts)
     local _vpriv = box.space[box.schema.VPRIV_ID]
     local spaces = box.space[box.schema.VSPACE_ID].index.owner:select{uid}
     for k, tuple in pairs(spaces) do
-        box.space[tuple[1]]:drop()
+        box.space[tuple.id]:drop()
     end
     local funcs = box.space[box.schema.VFUNC_ID].index.owner:select{uid}
     for k, tuple in pairs(funcs) do
-        box.schema.func.drop(tuple[1])
+        box.schema.func.drop(tuple.id)
     end
     -- if this is a role, revoke this role from whoever it was granted to
     local grants = _vpriv.index.object:select{'role', uid}
     for k, tuple in pairs(grants) do
-        revoke(tuple[2], tuple[2], uid)
+        revoke(tuple.grantee, tuple.grantee, uid)
     end
     local sequences = box.space[box.schema.VSEQUENCE_ID].index.owner:select{uid}
     for k, tuple in pairs(sequences) do
-        box.schema.sequence.drop(tuple[1])
+        box.schema.sequence.drop(tuple.id)
     end
     -- xxx: hack, we have to revoke session and usage privileges
     -- of a user using a setuid function in absence of create/drop
     -- privileges and grant option
-    if box.space._vuser:get{uid}[4] == 'user' then
+    if box.space._vuser:get{uid}.type == 'user' then
         box.session.su('admin', box.schema.user.revoke, uid,
                        'session,usage', 'universe', nil, {if_exists = true})
     end
@@ -2309,7 +2307,8 @@ local function drop(uid, opts)
     for k, tuple in pairs(privs) do
         -- we need an additional box.session.su() here, because of
         -- unnecessary check for privilege PRIV_REVOKE in priv_def_check()
-        box.session.su("admin", revoke, uid, uid, tuple[5], tuple[3], tuple[4])
+        box.session.su("admin", revoke, uid, uid, tuple.privilege,
+                       tuple.object_type, tuple.object_id)
     end
     box.space[box.schema.USER_ID]:delete{uid}
 end
@@ -2369,7 +2368,8 @@ local function info(id)
     for _, v in pairs(_priv:select{id}) do
         table.insert(
             privs,
-            {privilege_name(v[5]), v[3], object_name(v[3], v[4])}
+            {privilege_name(v.privilege), v.object_type,
+             object_name(v.object_type, v.object_id)}
         )
     end
     return privs
diff --git a/test/box/alter.result b/test/box/alter.result
index c1b1de13..75d6dae2 100644
--- a/test/box/alter.result
+++ b/test/box/alter.result
@@ -52,25 +52,10 @@ _space:insert{_space.id, ADMIN, '_space', 'memtx', 0, EMPTY_MAP, {}}
 ---
 - error: Duplicate key exists in unique index 'primary' in space '_space'
 ...
-_space:replace{_space.id, ADMIN, '_space', 'memtx', 0, EMPTY_MAP, {}}
----
-- [280, 1, '_space', 'memtx', 0, {}, []]
-...
 _space:insert{_index.id, ADMIN, '_index', 'memtx', 0, EMPTY_MAP, {}}
 ---
 - error: Duplicate key exists in unique index 'primary' in space '_space'
 ...
-_space:replace{_index.id, ADMIN, '_index', 'memtx', 0, EMPTY_MAP, {}}
----
-- [288, 1, '_index', 'memtx', 0, {}, []]
-...
---
--- Can't change properties of a space
---
-_space:replace{_space.id, ADMIN, '_space', 'memtx', 0, EMPTY_MAP, {}}
----
-- [280, 1, '_space', 'memtx', 0, {}, []]
-...
 --
 -- Can't drop a system space
 --
diff --git a/test/box/alter.test.lua b/test/box/alter.test.lua
index 733d27c5..3cb0c4f8 100644
--- a/test/box/alter.test.lua
+++ b/test/box/alter.test.lua
@@ -24,13 +24,7 @@ _space:insert{_space.id, ADMIN, 'test', 'world', 0, EMPTY_MAP, {}}
 -- There is already a tuple for the system space
 --
 _space:insert{_space.id, ADMIN, '_space', 'memtx', 0, EMPTY_MAP, {}}
-_space:replace{_space.id, ADMIN, '_space', 'memtx', 0, EMPTY_MAP, {}}
 _space:insert{_index.id, ADMIN, '_index', 'memtx', 0, EMPTY_MAP, {}}
-_space:replace{_index.id, ADMIN, '_index', 'memtx', 0, EMPTY_MAP, {}}
---
--- Can't change properties of a space
---
-_space:replace{_space.id, ADMIN, '_space', 'memtx', 0, EMPTY_MAP, {}}
 --
 -- Can't drop a system space
 --
-- 
2.11.0