Spec: https://html.spec.whatwg.org/multipage/#dom-textarea/input-setrangetext
In order to do this, we need to define the SelectionMode enum in WebIDL:
https://html.spec.whatwg.org/multipage/#selectionmode
Since the enum is used by HTMLTextAreaElement and HTMLInputElement, it
doesn't seem to make sense to define it in the WebIDL file for one or
other of those.
However, we also can't create a stand-alone SelectionMode.webidl file,
because the current binding-generation code won't generate a "pub mod
SelectionMode;" line in mod.rs unless SelectionMode.webidl contains
either an interface or a namespace. (This logic happens in
components/script/dom/bindings/codegen/Configuration.py:35, in the
Configuration.__init__ method.)
I thought about changing the binding-generation code, but that seems
difficult. So I settled for placing the enum inside
HTMLFormElement.webidl, as that seems like a "neutral" location. We
could equally settle for putting it under HTMLTextAreaElement or
HTMLInputElement, it probably doesn't really matter.
The setRangeText algorithm set the "dirty value flag" on the
input/textarea. I made some clean-ups related to this:
1. HTMLTextAreaElement called its dirty value flag "value_changed"; I
changed this to "value_dirty" to be consistent with the spec.
2. HTMLInputElement had a "value_changed" field and also a "value_dirty"
field, which were each used in slightly different places (and
sometimes in both places). I consolidated these into a single
"value_dirty" field, which was necessary in order to make some of the
tests pass.
TextControl::set_dom_range_text replaces part of the existing textinput
content with the replacement string (steps 9-10 of the algorithm). My
implementation changes the textinput's selection and then replaces the
selection. A downside of this approach is that we lose the original
selection state from before the call to setRangeText. Therefore, we have
to save the state into the original_selection_state variable so that we
can later pass it into TextControl::set_selection_range. This allows
TextControl::set_selection_range to correctly decide whether or not to
fire the select event.
An alternative approach would be to implement a method on TextInput
which allows a subtring of the content to be mutated, without touching
the current selection state. However, any such method would potentially
put the TextInput into an inconsistent state where the edit_point and/or
selection_origin is a TextPoint which doesn't exist in the content. It
would be up to the caller to subsequently make sure that the TextInput
gets put back into a valid state (which would actually happen, when
TextControl::set_selection_range is called).
I think TextInput's public API should not make it possible to put it
into an invalid state, as that would be a potential source of bugs.
That's why I didn't take this approach. (TextInput's public API does
currently make it possible to create an invalid state, but I'd like to
submit a follow-up patch to lock this down.)
This came out of a conversation with nox in IRC:
https://mozilla.logbot.info/servo/20171201#c13946454-c13946594
The code I was working on which motivated this change is here:
https://github.com/servo/servo/pull/19461
Previously, InputType::Text was used to represent several different
values of the type attribute on an input element.
If an input element doesn't have a type attribute, or its type attribute
doesn't contain a recognised value, then the input's type defaults to
"text".
Before this change, there were a number of checks in the code which
directly looked at the type attribute. If those checks matched against
the value "text", then they were potentially buggy, since an input with
type=invalid should also behave like an input with type=text.
Rather than have every conditional which cares about the input type also
have to deal with invalid input types, we can convert the type attribute
to an InputType enum once, and then match against the enum.
A secondary benefit is that the compiler can tell us whether we've
missed branches in a match expression. While working on this I
discovered that the HTMLInputElement::value_mode() method misses a case
for inputs with type=hidden (this resulted in a failing WPT test
passing).
I've also implemented the Default trait for InputType, so we now only
have one place in the code which knows that InputType::Text is the
default, where previously there were several.
I had to change the test a little bit to avoid some failures due to
color and text both having a sanitizedValue which was making the test
use the first assertion instead of the second one in some cases.
The sanitize_value implementation is pretty simple, we iterate over the
content and checks that the content is 7 characters long, that the first
character is a `#` and then that all the following characters are
hexadecimal. If all those requirements are met, we lowercase the
content, otherwise we put `#000000` in it.
The three tests that are marked as failures are because they use offsetWidth as a dummy to force a layout flush. Now that these exist, they expose an unrelated bug with reflow.
