Use filters with expressions

[almousa1990]

Hi,

For some reasons, filters don't seem to work when evaluating and expressions, for example, the following will always evaluate (with filters):

{% assign people = "alice, bob, carol" | split: ", " -%}
{%- if people | size == 1 -%}shouldn't evaulate{%- endif%}

The following will not evaluate:

{% assign people = "alice, bob, carol" | split: ", " -%}
{%- if people.size == 1 -%}shouldn't evaulate{%- endif%}

Note that both conditions should have the same outcome

[harttle]

I tried the Ruby version just to find it doesn't support this too. But I'm happy to have this feature in LiquidJS. I'll keep this open till someone implement it.

[harttle]

The operator priority is another potential issue to use filters in expressions.

{{ foo | bar: 'a'  ==  'b' }}  // one may expect == has higher priority
{{ people | size == 1 }}     // one may expect '|' has higher priority

But I managed to make this work (the | always has higher priority, which is more intuitive and compliant to the current implementation):

liquidjs/test/integration/builtin/tags/if.ts

Lines 84 to 89 in 2430672

	it('should support filter on expression', async function () {
	liquid.registerFilter('negate', (val) => !val)
	const src = '{% if 2 == 3 | negate %}yes{%else%}no{%endif%}'
	const html = await liquid.parseAndRender(src, scope)
	return expect(html).to.equal('yes')
	})

Now filters are available for expressions in if, unless and case.