Allow iteration on a string

[Stepland]

I wanted to add some silly per-character rainbow text for my own blog with this style

I managed to do so with split but it feels hacky

{%- macro rainbow(text) -%}
{%- set color_index = 0 -%}
{%- set text_length = text | length -%}
{%- set text_array = text | split(pat="") | slice(start=1, end=-1) -%}
{%- for i in range(end=text_length) -%}
    {%- set char = text_array | nth(n=i) -%}
    {%- if char != " " -%}
        <span class="color-{{ color_index % 6 }}">{{ char }}</span>
        {%- set_global color_index = color_index + 1 -%}
    {%- else %} {% endif -%}
{%- endfor -%}
{%- endmacro input -%}

Adding the ability to iterate on characters with a filter reduces it to

{%- macro rainbow(text) -%}
{%- set color_index = 0 -%}
{%- for char in text | chars -%}
    {%- if char != " " -%}
        <span class="color-{{ color_index % 6 }}">{{ char }}</span>
        {%- set_global color_index = color_index + 1 -%}
    {%- else %} {% endif -%}
{%- endfor -%}
{%- endmacro input -%}

I feel like tera not allowing strings to be iterated on directly was intentional so I chose to implement it as a filter. Using filters also allows for other ways of iterating on a string to be implemented, even though I can't think of another useful way to iterate on a string right now.

[Keats]

I feel like tera not allowing strings to be iterated on directly was intentional

Not really, more like an oversight. If it works in Jinja2, it should work here as well in this case.

[Keats]

@Stepland are you interested in implementing iteration on strings?

[Stepland]

I'll try !

[Stepland]

I first tried repurposing ForLoopValues::Array for this but I couldn't figure out how to make it work without turning current_value() into a big mess, so instead I made a new enum variant

[Keats]

LGTM but can you add some tests?

[Keats]

Actually wait, using .chars will not work as expected. You want to make the unic-segment non optional and use that (see the truncate filter for an example).
See https://doc.rust-lang.org/std/primitive.char.html#representation for details

[Stepland]

Nice catch !

I added only one test. I think it is enough to check that string iteration gives back grapheme clusters and not something else like codepoints. I feel like adding more tests would just result in testing unic-segment by proxy.

[Keats]

Thanks, I'll merge/release it next week!

[Keats]

I should stop giving time estimates haha
Thanks, I'll release it now