defmodule Cldr.Route do
@moduledoc """
Generate localized routes and route helper
modules.
This module when `use`d , provides a `localize/1`
macro that is designed to wrap the standard Phoenix
route macros such as `get/3`, `put/3` and `resources/3`
and localizes them for each locale defined in a Gettext
backend module attached to a Cldr backend module.
Translations for the parts of a given route path are
translated at compile-time and are then combined into
a localised route that is added to the standard
Phoenix routing framework.
As a result, users can enter URLs using localised
terms which can enhance user engagement and content
relevance.
Similarly, localised path and URL helpers are
generated that wrap the standard Phoenix helpers to
supporting generating localised paths and URLs.
### Configuration
A Cldr backend module that configures a `Gettext`
asosciated backend is required.
Path parts (the parts between "/") are translated
at compile time using `Gettext`. Therefore localization
can only be applied to locales that are defined in
a [gettext backend module](https://hexdocs.pm/gettext/Gettext.html#module-using-gettext)
that is configured in a `Cldr` backend module.
For example:
```
defmodule MyApp.Cldr do
use Cldr,
locales: ["en", "fr"],
default_locale: "en".
gettext: MyApp.Gettext
providers: [Cldr.Route]
end
```
Here the `MyApp.Cldr` backend module
is used to instrospect the configured
locales in order to drive the localization
generation.
Next, configure the router module to
use the `localize/1` macro by adding
`use MyApp.Cldr.Route` to the module and invoke
the `localize/1` macro to wrap the required
routes. For example:
```elixir
defmodule MyApp.Router do
use Phoenix.Router
use MyApp.Cldr.Routes
localize do
get "/pages/:page", PageController, :show
resources "/users", UserController
end
end
```
The following routes are generated in the `MyApp.Router`
module (assuming that translations are updated in the `Gettext`
configuration).
For this example, the `:fr` and `:de` translations are
the same as the `:en` text with `_fr` or `_de` appended.
```bash
% mix phx.routes MyApp.Router
page_de_path GET /pages_de/:page PageController :show
page_en_path GET /pages/:page PageController :show
page_fr_path GET /pages_fr/:page PageController :show
user_de_path GET /users_de UserController :index
user_de_path GET /users_de/:id/edit UserController :edit
user_de_path GET /users_de/new UserController :new
user_de_path GET /users_de/:id UserController :show
...
```
It is also possible to emit the routes and route helpers before
localization using the `mix phx.routes` task on an automatically
generated mini-router. See `h MyApp.Router.LocalizedRoutes`.
### Interpolating Locale Data
A route may be defined with elements of the locale
interpolated into it. These interpolations are specified
using the normal `\#{}` interpolation syntax. However
since route translation occurs at compile time only
the following interpolations are supported:
* `locale` will interpolate the Cldr locale name
* `language` will interpolate the Cldr language name
* `territory` will interpolate the Cldr territory code
Some examples are:
```elixir
localize do
get "/\#{locale}/locale/pages/:page", PageController, :show
get "/\#{language}/language/pages/:page", PageController, :show
get "/\#{territory}/territory/pages/:page", PageController, :show
end
```
### Localized Helpers
Manually constructing the localized helper names shown in
the example above would be tedious. Therefore a `LocalizedHelpers`
module is generated at compile-time. Assuming the router
module is called `MyApp.Router` then the full name of the
localized helper module is `MyApp.Router.LocalizedHelpers`.
The functions on this module are the non-localized versions.
Localised routes can be printed by leveraging the `phx.routes`
mix task. For example:
```elixir
% mix phx.routes MyApp.Router
page_de_path GET /pages_de/:page PageController :show
page_en_path GET /pages/:page PageController :show
page_fr_path GET /pages_fr/:page PageController :show
user_de_path GET /users_de UserController :index
user_de_path GET /users_de/:id/edit UserController :edit
user_de_path GET /users_de/new UserController :new
user_de_path GET /users_de/:id UserController :show
user_de_path POST /users_de UserController :create
user_de_path PATCH /users_de/:id UserController :update
PUT /users_de/:id UserController :update
.....
```
The functions on the `MyApp.Router.LocalizedHelpers` module all
respect the current locale, based upon `Cldr.get_locale/1`, and will
delegate to the appropriate localized function in the
`MyApp.Router.Helpers` module created automatically by Phoenix
at compile time.
### Configuring Localized Helpers as default
Since `LocalizedHelpers` have the same semantics and
API as the standard `Helpers` module it is possible to
update the generated Phoenix configuration to use the
`LocalizedHelpers` module by default. Assuming the
presence of `myapp_web.ex` defining the module `MyAppWeb`
then changing the `view_helpers` function from
```elixir
defp view_helpers do
quote do
...
import MyAppWeb.ErrorHelpers
import MyAppWeb.Gettext
alias MyAppWeb.Router.Helpers, as: Routes
end
end
```
to
```elixir
defp view_helpers do
quote do
...
import MyAppWeb.ErrorHelpers
import MyAppWeb.Gettext
alias MyAppWeb.Router.LocalizedHelpers, as: Routes
end
end
```
will result in the automatic use of the localized
helpers rather than the standard helpers.
### Translations
In order for routes to be localized, translations must be
provided for each path segment. This translation is performed
by `Gettext.dgettext/3` with the domain "routes". Therefore for
each configured locale, a "routes.pot" file is required containing
the path segment translations for that locale.
Using the example Cldr backend that has "en" and "fr" Gettext
locales then the directory structure would look like the following
(if the default Gettext configuration is used):
priv/gettext
├── default.pot
├── en
│ └── LC_MESSAGES
│ ├── default.po
│ ├── errors.po
│ └── routes.po
├── errors.pot
└── fr
└── LC_MESSAGES
├── default.po
├── errors.po
└── routes.po
"""
@domain "routes"
@path_separator "/"
@interpolate ":"
@localizable_verbs [
:resources,
:get,
:put,
:patch,
:post,
:delete,
:options,
:head,
:connect,
:live
]
@doc false
def cldr_backend_provider(config) do
backend = config.backend
gettext = config.gettext
quote location: :keep, bind_quoted: [backend: backend, gettext: gettext] do
defmodule Routes do
@moduledoc false
defmacro __using__(opts) do
Cldr.Route.confirm_backend_has_gettext!(unquote(backend))
caller = __CALLER__.module
Module.put_attribute(caller, :_cldr_backend, unquote(backend))
quote do
import Cldr.Route, only: :macros
@before_compile Cldr.Route
end
end
end
end
end
@doc false
def confirm_backend_has_gettext!(backend) do
confirm_backend_has_gettext!(backend, backend.__cldr__(:config))
end
@doc false
def confirm_backend_has_gettext!(backend, %Cldr.Config{gettext: nil}) do
raise ArgumentError,
"""
The Cldr backend #{inspect(backend)} does not have a Gettext
module configured.
A Gettext module must be configured in order to define localized
routes. In addition, translations must be provided for the Gettext
backend under the "routes" domain (ie in a file "routes.pot" for
each configured Gettext locale).
"""
end
def confirm_backend_has_gettext!(_backend, %Cldr.Config{} = _config) do
:ok
end
@doc false
def localizable_verbs do
@localizable_verbs
end
@doc false
defmacro __before_compile__(env) do
alias Cldr.Route.LocalizedHelpers
routes = env.module |> Module.get_attribute(:phoenix_routes) |> Enum.reverse()
localized_routes = Cldr.Route.routes(routes)
# Remove bookkeeping data in :private
Module.delete_attribute(env.module, :phoenix_routes)
Module.register_attribute(env.module, :phoenix_routes, [])
Module.put_attribute(env.module, :phoenix_routes, Cldr.Route.delete_original_path(routes))
routes_with_exprs = Enum.map(routes, &{&1, Phoenix.Router.Route.exprs(&1)})
helpers_moduledoc = Module.get_attribute(env.module, :helpers_moduledoc)
LocalizedHelpers.define(env, routes_with_exprs, docs: helpers_moduledoc)
quote do
defmodule LocalizedRoutes do
@moduledoc """
This module exists only to host route definitions.
Localised routes can be printed by leveraging
the `phx.routes` mix task. For example:
% mix phx.routes #{inspect(__MODULE__)}
page_path GET /pages/:page PageController :show
user_path GET /users UserController :index
user_path GET /users/:id/edit UserController :edit
user_path GET /users/new UserController :new
user_path GET /users/:id UserController :show
.....
"""
def __routes__ do
unquote(Macro.escape(localized_routes))
end
end
end
end
@doc false
def delete_original_path(routes) do
Enum.map(routes, fn route ->
private = Map.delete(route.private, :original_path)
Map.put(route, :private, private)
end)
end
@doc """
Generates localised routes for each locale defined in a
Cldr backend.
This macro is intended to wrap a series of standard
route definitiosn in a `do` block. For example:
```elixir
localize do
get "/pages/:page", PageController, :show
resources "/users", UsersController
end
```
"""
defmacro localize(do: {:__block__, meta, routes}) do
translated_routes =
for route <- routes do
quote do
localize(do: unquote(route))
end
end
{:__block__, meta, translated_routes}
end
defmacro localize(do: route) do
cldr_backend = Module.get_attribute(__CALLER__.module, :_cldr_backend)
gettext_backend = cldr_backend.__cldr__(:config).gettext
cldr_locale_names = locales_from_unique_gettext_locales(cldr_backend)
unless gettext_backend do
raise "Cldr backend #{cldr_backend} does not have a configured Gettext backend."
end
quote do
require unquote(gettext_backend)
localize(unquote(cldr_locale_names), do: unquote(route))
end
end
@doc """
Generates localised routes for each locale provided.
This macro is intended to wrap a series of standard
route definitiosn in a `do` block. For example:
```elixir
localize [:en, :fr] do
get "/pages/:page", PageController, :show
resources "/users", UsersController
end
```
"""
defmacro localize(cldr_locale_names, do: {:__block__, meta, routes})
when is_list(cldr_locale_names) do
translated_routes =
for route <- routes do
quote do
localize(unquote(cldr_locale_names), do: unquote(route))
end
end
{:__block__, meta, translated_routes}
end
defmacro localize(cldr_locale_names, do: route) when is_list(cldr_locale_names) do
cldr_backend = Module.get_attribute(__CALLER__.module, :_cldr_backend)
for cldr_locale_name <- cldr_locale_names do
with {:ok, cldr_locale} <- cldr_backend.validate_locale(cldr_locale_name) do
if cldr_locale.gettext_locale_name do
quote do
localize(unquote(cldr_locale), unquote(route))
end
else
warn_no_gettext_locale(cldr_locale_name, route)
end
else
{:error, {exception, reason}} -> raise exception, reason
end
end
|> Enum.reject(&is_nil/1)
|> Enum.uniq_by(&canonical_route/1)
end
defmacro localize(locale, do: {:__block__, meta, routes}) do
translated_routes =
for route <- routes do
quote do
localize(unquote(locale), do: unquote(route))
end
end
{:__block__, meta, translated_routes}
end
defmacro localize(locale, do: route) do
quote do
localize(unquote(locale), unquote(route))
end
end
# Rewrite nested resources; guard against infinite recursion
defmacro localize(locale, {:resources, _, [path, controller, [do: {fun, _, _}] = nested]})
when fun != :localize do
nested = localize_nested_resources(locale, nested)
quote do
localize unquote(locale) do
resources unquote(path), unquote(controller) do
unquote(nested)
end
end
end
end
# Do the actual translations
defmacro localize(cldr_locale_name, {verb, meta, [path | args]}) when verb in @localizable_verbs do
cldr_backend = Module.get_attribute(__CALLER__.module, :_cldr_backend)
do_localize(:private, cldr_locale_name, cldr_backend, {verb, meta, [path | args]})
end
# If the verb is unsupported for localization
defmacro localize(_cldr_locale_name, {verb, _meta, [path | args]}) do
{args, []} = Code.eval_quoted(args)
args = Enum.map_join(args, ", ", &inspect/1)
raise ArgumentError,
"""
Invalid route for localization: #{verb} #{inspect(path)}, #{inspect(args)}
Allowed localizable routes are #{inspect(@localizable_verbs)}
"""
end
defp do_localize(field, cldr_locale_name, cldr_backend, {verb, meta, [path | args]} = route) do
gettext_backend = cldr_backend.__cldr__(:config).gettext
{:ok, cldr_locale} = cldr_backend.validate_locale(cldr_locale_name)
{original_path, _} = escape_interpolation(path) |> Code.eval_quoted()
if cldr_locale.gettext_locale_name do
translated_path =
path
|> interpolate(cldr_locale)
|> combine_string_segments()
|> :erlang.iolist_to_binary()
|> translate_path(gettext_backend, cldr_locale.gettext_locale_name)
args =
add_to_route(args, field, :cldr_locale, cldr_locale)
|> add_to_route(:private, :original_path, original_path)
|> localise_helper(verb, cldr_locale.gettext_locale_name)
quote do
unquote({verb, meta, [translated_path | args]})
end
else
warn_no_gettext_locale(cldr_locale_name, route)
quote do
unquote({verb, meta, [path | args]})
end
end
end
defp localize_nested_resources(locale, nested) do
Macro.postwalk nested, fn
{:resources, _, [_path, _meta, _args, [do: {:resources, _, _}]]} = resources ->
quote do
localize unquote(locale) do
unquote(resources)
end
end
{:resources, _, [_path, _meta, [do: {:resources, _, _}]]} = resources ->
quote do
localize unquote(locale) do
unquote(resources)
end
end
{:resources, _, _} = route ->
quote do
localize unquote(locale), unquote(route)
end
other ->
other
end
end
defp locales_from_unique_gettext_locales(cldr_backend) do
cldr_backend.known_locale_names()
|> Enum.map(&cldr_backend.validate_locale/1)
|> Enum.map(&elem(&1, 1))
|> Enum.uniq_by(&(&1.gettext_locale_name))
|> Enum.reject(&is_nil/1)
|> Enum.map(&(&1.cldr_locale_name))
end
# Interpolates the locale, language and territory
# into he path by splicing the AST
defp interpolate(path, locale) do
Macro.prewalk path, fn
{{:., _, [Kernel, :to_string]}, _, [{:locale, _, _}]} ->
to_string(locale.cldr_locale_name) |> String.downcase()
{{:., _, [Kernel, :to_string]}, _, [{:language, _, _}]} ->
to_string(locale.language) |> String.downcase()
{{:., _, [Kernel, :to_string]}, _, [{:territory, _, _}]} ->
to_string(locale.territory) |> String.downcase()
other ->
other
end
end
# Since we are doing com[ile-time translation of the
# path, the path needs to be a string (not an expression).
# This function attempts to combine the segments and
# raises an exception if a string cannot be created.
defp combine_string_segments([]) do
[]
end
defp combine_string_segments(a) when is_binary(a) do
[a]
end
defp combine_string_segments({:"::", _, [a, {:binary, _, _}]}) do
[a]
end
defp combine_string_segments({:<<>>, _, [a | b]}) do
[combine_string_segments(a) | combine_string_segments(b)]
end
defp combine_string_segments({:<>, _, [a, b]}) do
[combine_string_segments(a), combine_string_segments(b)]
end
defp combine_string_segments([a | rest]) do
[combine_string_segments(a) | combine_string_segments(rest)]
end
defp combine_string_segments(ast) do
raise ArgumentError,
"""
The path arugment to a localized route must be a binary that
can be resolved at compile time. Found:
#{Macro.to_string(ast)}
"""
end
# Localise the helper name for the a verb (except resources)
defp localise_helper(args, verb, locale) when verb not in [:resources] do
[{_aliases, _meta, controller} | _rest] = args
configured_helper = get_option(args, :as)
helper = helper_name(controller, locale, configured_helper)
put_option(args, :as, String.to_atom(helper))
end
# It appears that `:name` is overridden by `:as` :-(
defp localise_helper(args, :resources, locale) do
case args do
[controller, options, do_block] ->
{_aliases, _meta, controller_name} = controller
configured_helper = get_option(args, :as)
options =
options
|> Keyword.put(:name, name(controller_name))
|> Keyword.put(:as, helper_name(controller_name, locale, configured_helper))
[controller, options, do_block]
[controller, _options] ->
{_aliases, _meta, controller} = controller
configured_helper = get_option(args, :as)
helper = helper_name(controller, locale, configured_helper)
put_option(args, :as, helper)
end
end
defp name(controller) do
Phoenix.Naming.resource_name(Module.concat(controller), "Controller")
end
defp helper_name(controller, locale, nil) do
Phoenix.Naming.resource_name(Module.concat(controller), "Controller") <> "_" <> locale
end
defp helper_name(_controller, locale, configured_helper) do
configured_helper <> "_" <> locale
end
defp get_option([_controller, _action, options], field) do
Keyword.get(options, field)
end
defp get_option([_controller, options], field) do
Keyword.get(options, field)
end
# For non-live routes
defp put_option([controller, action, options], field, value) do
[controller, action, [{field, value} | options]]
end
# For live routes
defp put_option([controller, options], field, value) do
[controller, [{field, value} | options]]
end
defp warn_no_gettext_locale(cldr_locale_name, route) do
{verb, _meta, [path, _controller | _args]} = route
IO.warn(
"No known gettext locale for #{inspect(cldr_locale_name)}. " <>
"No #{inspect(cldr_locale_name)} localized routes will be generated " <>
"for #{inspect(verb)} #{Macro.to_string(path)}",
[]
)
nil
end
# Gettext requires we set the current process locale
# in order to translate. This might ordinarily disrupt
# any user set locale. However since this is only executed
# at compile time it does not affect runtime behaviour.
@doc false
def translate_path(path, gettext_backend, locale) do
path
|> String.split(@path_separator)
|> Enum.map(&translate_part(gettext_backend, locale, &1))
|> reduce_parts()
end
defp translate_part(_gettext_backend, _locale, "" = part), do: part
defp translate_part(_gettext_backend, _locale, @interpolate <> _rest = part), do: part
defp translate_part(gettext_backend, locale, part) do
domain = @domain
quote do
Gettext.put_locale(unquote(gettext_backend), unquote(locale))
unquote(gettext_backend).dgettext(unquote(domain), unquote(part))
end
end
defp reduce_parts([]), do: []
defp reduce_parts([a, b]), do: {:<>, [], [a, {:<>, [], ["/", b]}]}
defp reduce_parts([a | b]), do: {:<>, [], [a, {:<>, [], ["/", reduce_parts(b)]}]}
# Add an assign :cldr_locale that is the
# gettext locale for which this route was recognised.
# This can be used by application code to make localization
# decisions. Its also used to mark localised routes
# for path and url helper generation.
# When inserting the assigns, make sure to keep any
# do: block in the correct place
@doc false
def add_to_route(args, field, key, value) do
case Enum.reverse(args) do
[[do: block], last | rest] ->
last
|> put_route(field, key, value)
|> combine(rest, do: block)
|> Enum.reverse()
[last | rest] ->
last
|> put_route(field, key, value)
|> combine(rest)
|> Enum.reverse()
[] = last ->
put_route(last, field, key, value)
end
end
defp combine(first, rest) when is_list(first) and is_list(rest), do: first ++ rest
defp combine(first, rest), do: [first | rest]
defp combine(first, rest, block) when is_list(first) and is_list(rest),
do: [block | first ++ rest]
defp combine(first, rest, block), do: [block, first | rest]
# Keyword list of options - update or add :private
defp put_route([{first, _value} | _rest] = options, field, key, value) when is_atom(first) do
{field_content, options} = Keyword.pop(options, field)
options = [Keyword.put(options, field, put_value(field_content, key, value))]
quote do
unquote(options)
end
end
# Not a keyword list - fabricate one
defp put_route(last, field, key, value) do
options =
quote do
[{unquote(field), %{unquote(key) => unquote(Macro.escape(value))}}]
end
[options, last]
end
defp put_value(nil, key, value) do
quote do
%{unquote(key) => unquote(Macro.escape(value))}
end
end
defp put_value({:%{}, meta, key_values}, key, value) do
{:%{}, meta, [{key, Macro.escape(value)} | key_values]}
end
# Testing uniqeness of a routes excluding options
# We use this to eliminate duplicate routes which can occur if
# there is no translation for a term and therefore the original
# term is returned.
defp canonical_route({verb, meta, [path, controller, action | _args]}) when is_atom(action) do
{verb, meta, [path, controller, action]}
end
defp canonical_route({verb, meta, [path, controller | _args]}) do
{verb, meta, [path, controller]}
end
defp canonical_route({:localize, _, [[do: {verb, meta, [path, controller, action]}]]})
when is_atom(action) do
{verb, meta, [path, controller, action]}
end
@route_keys [:verb, :path, :plug, :plug_opts, :helper, :metadata]
@doc false
def routes(routes) do
routes
|> Enum.map(&strip_locale_from_helper/1)
|> Enum.map(&add_locales_to_metadata/1)
|> group_locales_by_path_helper_verb()
|> Enum.map(&Map.take(&1, @route_keys))
end
defp group_locales_by_path_helper_verb([]) do
[]
end
# When the routes match except for locale
defp group_locales_by_path_helper_verb([
%{path: path, helper: helper, verb: verb} = first,
%{path: path, helper: helper, verb: verb} = second | rest]) do
locales = Enum.uniq([locale_from_args(second) | first.metadata.locales]) |> Enum.sort()
metadata = Map.put(first.metadata, :locales, locales)
group_locales_by_path_helper_verb([%{first | metadata: metadata} | rest])
end
defp group_locales_by_path_helper_verb([first | rest]) do
[first | group_locales_by_path_helper_verb(rest)]
end
# We add the locales for a given route into the metadata field
# of the route. This means later processing can identify which locales
# are applicable to which routes. Note this applies only to the
# routes being stored in `LocalizedRoutes`, not the routes
# stored in `MyApp.Router` - the latter are the active routes
# used by Phoenix for route detection.
defp add_locales_to_metadata(%{assigns: %{cldr_locale: locale}} = route) do
metadata = Map.put(route.metadata, :locales, [locale])
%{route | metadata: metadata}
end
defp add_locales_to_metadata(%{private: %{cldr_locale: locale}} = route) do
metadata = Map.put(route.metadata, :locales, [locale])
%{route | metadata: metadata}
end
defp add_locales_to_metadata(other) do
other
end
# For a given route, remove the locale suffixes (like "_fr") from
# the helper names to recover the original helper name that
# we define in `MyApp.Router.LocalizedHelpers`
defp strip_locale_from_helper(%{assigns: %{cldr_locale: locale}} = route) do
do_strip_locale_from_helper(route, locale)
end
defp strip_locale_from_helper(%{private: %{cldr_locale: locale}} = route) do
do_strip_locale_from_helper(route, locale)
end
defp strip_locale_from_helper(%{private: %{}} = other) do
other
end
defp strip_locale_from_helper(%{helper: nil} = route) do
route
end
defp do_strip_locale_from_helper(%{helper: helper} = route, locale) do
helper = Cldr.Route.LocalizedHelpers.strip_locale(helper, locale)
%{route | helper: helper}
end
defp locale_from_args(%{assigns: %{cldr_locale: locale}}) do
locale
end
defp locale_from_args(%{private: %{cldr_locale: locale}}) do
locale
end
defp locale_from_args(_other) do
nil
end
defp escape_interpolation(path) do
Macro.prewalk path, fn
{{:., _, [Kernel, :to_string]}, _, [{:locale, _, _}]} ->
~S"#{locale}"
{{:., _, [Kernel, :to_string]}, _, [{:language, _, _}]} ->
~S"#{language}"
{{:., _, [Kernel, :to_string]}, _, [{:territory, _, _}]} ->
~S"#{territory}"
other ->
other
end
end
end
