[PATCH v6 8/8] box: specify indexes in user-friendly form

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

Implemented a more convenient interface for creating an index
by JSON path. Instead of specifying fieldno and relative path
it comes possible to pass full JSON path to data.

Closes #1012

@TarantoolBot document
Title: Indexes by JSON path
Sometimes field data could have complex document structure.
When this structure is consistent across whole document,
you are able to create an index by JSON path.

Example:
s = box.schema.space.create('sample')
format = {{'id', 'unsigned'}, {'data', 'map'}}
s:format(format)
-- explicit JSON index creation
age_idx = s:create_index('age', {{2, 'number', path = ".age"}})
-- user-friendly syntax for JSON index creation
parts = {{'data.FIO["fname"]', 'str'}, {'data.FIO["sname"]', 'str'},
         {'data.age', 'number'}}
info_idx = s:create_index('info', {parts = parts}})
s:insert({1, {FIO={fname="James", sname="Bond"}, age=35}})
---
 src/box/lua/index.c       | 64 +++++++++++++++++++++++++++++++++++++++
 src/box/lua/schema.lua    | 22 +++++++-------
 test/engine/json.result   | 28 +++++++++++++++++
 test/engine/json.test.lua |  8 +++++
 4 files changed, 111 insertions(+), 11 deletions(-)

diff --git a/src/box/lua/index.c b/src/box/lua/index.c
index 6265c044a..9b04c5d9a 100644
--- a/src/box/lua/index.c
+++ b/src/box/lua/index.c
@@ -35,6 +35,9 @@
 #include "box/box.h"
 #include "box/index.h"
 #include "box/lua/tuple.h"
+#include "box/schema.h"
+#include "box/tuple_format.h"
+#include "json/json.h"
 #include "box/lua/misc.h" /* lbox_encode_tuple_on_gc() */
 
 /** {{{ box.index Lua library: access to spaces and indexes
@@ -328,6 +331,66 @@ lbox_index_compact(lua_State *L)
 	return 0;
 }
 
+/**
+ * Resolve field index by absolute JSON path first component and
+ * return relative JSON path.
+ */
+static int
+lbox_index_path_resolve(struct lua_State *L)
+{
+	if (lua_gettop(L) != 3 ||
+	    !lua_isnumber(L, 1) || !lua_isnumber(L, 2) || !lua_isstring(L, 3)) {
+		return luaL_error(L, "Usage box.internal."
+				     "path_resolve(part_id, space_id, path)");
+	}
+	uint32_t part_id = lua_tonumber(L, 1);
+	uint32_t space_id = lua_tonumber(L, 2);
+	size_t path_len;
+	const char *path = lua_tolstring(L, 3, &path_len);
+	struct space *space = space_cache_find(space_id);
+	if (space == NULL)
+		return luaT_error(L);
+	struct json_lexer lexer;
+	struct json_token token;
+	json_lexer_create(&lexer, path, path_len, TUPLE_INDEX_BASE);
+	int rc = json_lexer_next_token(&lexer, &token);
+	if (rc != 0) {
+		const char *err_msg =
+			tt_sprintf("options.parts[%d]: error in path on "
+				   "position %d", part_id, rc);
+		diag_set(ClientError, ER_ILLEGAL_PARAMS, err_msg);
+		return luaT_error(L);
+	}
+	assert(space->format != NULL && space->format->dict != NULL);
+	uint32_t fieldno = token.num;
+	uint32_t field_count = tuple_format_field_count(space->format);
+	if (token.type == JSON_TOKEN_NUM && fieldno >= field_count) {
+		const char *err_msg =
+			tt_sprintf("options.parts[%d]: field '%d' referenced "
+				   "in path is greater than format field "
+				   "count %d", part_id,
+				   fieldno + TUPLE_INDEX_BASE, field_count);
+		diag_set(ClientError, ER_ILLEGAL_PARAMS, err_msg);
+		return luaT_error(L);
+	} else if (token.type == JSON_TOKEN_STR &&
+		   tuple_fieldno_by_name(space->format->dict, token.str,
+					 token.len,
+					 field_name_hash(token.str, token.len),
+					 &fieldno) != 0) {
+		const char *err_msg =
+			tt_sprintf("options.parts[%d]: field was not found by "
+				   "name '%.*s'", part_id, token.len,
+				   token.str);
+		diag_set(ClientError, ER_ILLEGAL_PARAMS, err_msg);
+		return luaT_error(L);
+	}
+	fieldno += TUPLE_INDEX_BASE;
+	path += lexer.offset;
+	lua_pushnumber(L, fieldno);
+	lua_pushstring(L, path);
+	return 2;
+}
+
 /* }}} */
 
 void
@@ -365,6 +428,7 @@ box_lua_index_init(struct lua_State *L)
 		{"truncate", lbox_truncate},
 		{"stat", lbox_index_stat},
 		{"compact", lbox_index_compact},
+		{"path_resolve", lbox_index_path_resolve},
 		{NULL, NULL}
 	};
 
diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
index 8a804f0ba..497cf197c 100644
--- a/src/box/lua/schema.lua
+++ b/src/box/lua/schema.lua
@@ -575,7 +575,7 @@ local function update_index_parts_1_6_0(parts)
     return result
 end
 
-local function update_index_parts(format, parts)
+local function update_index_parts(format, parts, space_id)
     if type(parts) ~= "table" then
         box.error(box.error.ILLEGAL_PARAMS,
         "options.parts parameter should be a table")
@@ -626,16 +626,16 @@ local function update_index_parts(format, parts)
             box.error(box.error.ILLEGAL_PARAMS,
                       "options.parts[" .. i .. "]: field (name or number) is expected")
         elseif type(part.field) == 'string' then
-            for k,v in pairs(format) do
-                if v.name == part.field then
-                    part.field = k
-                    break
-                end
-            end
-            if type(part.field) == 'string' then
+            local idx, path = box.internal.path_resolve(i, space_id, part.field)
+            if part.path ~= nil and part.path ~= path then
                 box.error(box.error.ILLEGAL_PARAMS,
-                          "options.parts[" .. i .. "]: field was not found by name '" .. part.field .. "'")
+                          "options.parts[" .. i .. "]: field path '"..
+                          part.path.." doesn't math the path '" ..
+                          part.field .. "'")
             end
+            parts_can_be_simplified = parts_can_be_simplified and path == nil
+            part.field = idx
+            part.path = path or part.path
         elseif part.field == 0 then
             box.error(box.error.ILLEGAL_PARAMS,
                       "options.parts[" .. i .. "]: field (number) must be one-based")
@@ -792,7 +792,7 @@ box.schema.index.create = function(space_id, name, options)
         end
     end
     local parts, parts_can_be_simplified =
-        update_index_parts(format, options.parts)
+        update_index_parts(format, options.parts, space_id)
     -- create_index() options contains type, parts, etc,
     -- stored separately. Remove these members from index_opts
     local index_opts = {
@@ -959,7 +959,7 @@ box.schema.index.alter = function(space_id, index_id, options)
     if options.parts then
         local parts_can_be_simplified
         parts, parts_can_be_simplified =
-            update_index_parts(format, options.parts)
+            update_index_parts(format, options.parts, space_id)
         -- save parts in old format if possible
         if parts_can_be_simplified then
             parts = simplify_index_parts(parts)
diff --git a/test/engine/json.result b/test/engine/json.result
index c33e568b3..60d71bdfa 100644
--- a/test/engine/json.result
+++ b/test/engine/json.result
@@ -71,6 +71,34 @@ s:create_index('test2', {parts = {{2, 'number'}, {3, 'number', path = '.FIO.fnam
 - error: Field ["data"]["FIO"]["fname"] has type 'string' in one index, but type 'number'
     in another
 ...
+s:create_index('test3', {parts = {{2, 'number'}, {']sad.FIO["fname"]', 'str'}}})
+---
+- error: 'Illegal parameters, options.parts[2]: error in path on position 1'
+...
+s:create_index('test3', {parts = {{2, 'number'}, {'[666].FIO["fname"]', 'str'}}})
+---
+- error: 'Illegal parameters, options.parts[2]: field ''666'' referenced in path is
+    greater than format field count 5'
+...
+s:create_index('test3', {parts = {{2, 'number'}, {'invalid.FIO["fname"]', 'str'}}})
+---
+- error: 'Illegal parameters, options.parts[2]: field was not found by name ''invalid'''
+...
+idx3 = s:create_index('test3', {parts = {{2, 'number'}, {'data.FIO["fname"]', 'str'}}})
+---
+...
+assert(idx3 ~= nil)
+---
+- true
+...
+assert(idx3.parts[2].path == ".FIO[\"fname\"]")
+---
+- true
+...
+-- Vinyl has optimizations that omit index checks, so errors could differ.
+idx3:drop()
+---
+...
 s:insert{7, 7, {town = 'London', FIO = 666}, 4, 5}
 ---
 - error: 'Tuple field ["data"]["FIO"] type does not match one required by operation:
diff --git a/test/engine/json.test.lua b/test/engine/json.test.lua
index 45153743d..f91846d79 100644
--- a/test/engine/json.test.lua
+++ b/test/engine/json.test.lua
@@ -19,6 +19,14 @@ s:format(format)
 format = {{'id', 'unsigned'}, {'meta', 'unsigned'}, {'data', 'map'}, {'age', 'unsigned'}, {'level', 'unsigned'}}
 s:format(format)
 s:create_index('test2', {parts = {{2, 'number'}, {3, 'number', path = '.FIO.fname'}, {3, 'str', path = '["FIO"]["sname"]'}}})
+s:create_index('test3', {parts = {{2, 'number'}, {']sad.FIO["fname"]', 'str'}}})
+s:create_index('test3', {parts = {{2, 'number'}, {'[666].FIO["fname"]', 'str'}}})
+s:create_index('test3', {parts = {{2, 'number'}, {'invalid.FIO["fname"]', 'str'}}})
+idx3 = s:create_index('test3', {parts = {{2, 'number'}, {'data.FIO["fname"]', 'str'}}})
+assert(idx3 ~= nil)
+assert(idx3.parts[2].path == ".FIO[\"fname\"]")
+-- Vinyl has optimizations that omit index checks, so errors could differ.
+idx3:drop()
 s:insert{7, 7, {town = 'London', FIO = 666}, 4, 5}
 s:insert{7, 7, {town = 'London', FIO = {fname = 666, sname = 'Bond'}}, 4, 5}
 s:insert{7, 7, {town = 'London', FIO = {fname = "James"}}, 4, 5}
-- 
2.19.2