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forgejo/modules/context
wxiaoguang 722dab5286
Make HTML template functions support context (#24056)
# Background

Golang template is not friendly for large projects, and Golang template
team is quite slow, related:
* `https://github.com/golang/go/issues/54450`

Without upstream support, we can also have our solution to make HTML
template functions support context.

It helps a lot, the above Golang template issue `#54450` explains a lot:

1. It makes `{{Locale.Tr}}` could be used in any template, without
passing unclear `(dict "root" . )` anymore.
2. More and more functions need `context`, like `avatar`, etc, we do not
need to do `(dict "Context" $.Context)` anymore.
3. Many request-related functions could be shared by parent&children
templates, like "user setting" / "system setting"

See the test `TestScopedTemplateSetFuncMap`, one template set, two
`Execute` calls with different `CtxFunc`.

# The Solution

Instead of waiting for upstream, this PR re-uses the escaped HTML
template trees, use `AddParseTree` to add related templates/trees to a
new template instance, then the new template instance can have its own
FuncMap , the function calls in the template trees will always use the
new template's FuncMap.

`template.New` / `template.AddParseTree` / `adding-FuncMap` are all
quite fast, so the performance is not affected.

The details:

1. Make a new `html/template/Template` for `all` templates
2. Add template code to the `all` template
3. Freeze the `all` template, reset its exec func map, it shouldn't
execute any template.
4. When a router wants to render a template by its `name`
    1. Find the `name` in `all`
    2. Find all its related sub templates
3. Escape all related templates (just like what the html template
package does)
4. Add the escaped parse-trees of related templates into a new (scoped)
`text/template/Template`
    5. Add context-related func map into the new (scoped) text template
    6. Execute the new (scoped) text template
7. To improve performance, the escaped templates are cached to `template
sets`

# FAQ

## There is a `unsafe` call, is this PR unsafe?

This PR is safe. Golang has strict language definition, it's safe to do
so: https://pkg.go.dev/unsafe#Pointer (1) Conversion of a *T1 to Pointer
to *T2


## What if Golang template supports such feature in the future?

The public structs/interfaces/functions introduced by this PR is quite
simple, the code of `HTMLRender` is not changed too much. It's very easy
to switch to the official mechanism if there would be one.

## Does this PR change the template execution behavior?

No, see the tests (welcome to design more tests if it's necessary)

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: Giteabot <teabot@gitea.io>
2023-04-20 04:08:58 -04:00
..
access_log.go Correct the access log format (#24085) 2023-04-13 21:14:06 +08:00
api.go Set X-Gitea-Debug header once (#23361) 2023-03-08 15:40:04 -05:00
api_org.go
api_test.go
auth.go Refactor cookie (#24107) 2023-04-13 15:45:33 -04:00
captcha.go Add new captcha: cloudflare turnstile (#22369) 2023-02-05 15:29:03 +08:00
context.go Make HTML template functions support context (#24056) 2023-04-20 04:08:58 -04:00
csrf.go Refactor cookie (#24107) 2023-04-13 15:45:33 -04:00
form.go
org.go Add missing tabs to org projects page (#22705) 2023-03-10 09:18:20 -06:00
package.go Improve permission check of packages (#23879) 2023-04-06 22:18:29 +08:00
pagination.go Make branches list page operations remember current page (#23420) 2023-03-14 13:11:38 +08:00
permission.go
private.go
repo.go Allow adding new files to an empty repo (#24164) 2023-04-19 21:40:42 +08:00
response.go
utils.go
xsrf.go
xsrf_test.go