Regex with replace in Golang

I've used regexp package to replace bellow text

{% macro products_list(products) %}
{% for product in products %}
productsList
{% endfor %}
{% endmacro %}

but I could not replace "products" without replace another words like "products_list" and Golang has no a func like re.ReplaceAllStringSubmatch to do replace with submatch (there's just FindAllStringSubmatch). I've used re.ReplaceAllString to replace "products" with .

{% macro ._list(.) %}
{% for product in . %}
.List
{% endfor %}
{% endmacro %}

It's not sth which I want and I need below result:

{% macro products_list (.) %}
{% for product in . %}
productsList
{% endfor %}
{% endmacro %}

You can use capturing groups with alternations matching either string boundaries or a character not _ (still using a word boundary):

var re = regexp.MustCompile(`(^|[^_])\bproducts\b([^_]|$)`)
s := re.ReplaceAllString(sample, `$1.$2`)

Here is the Go demo and a regex demo.

Notes on the pattern:

• (^|[^_]) - match string start (^) or a character other than _
• \bproducts\b - a whole word "products"
• ([^_]|$) - either a non-_ or the end of string.

In the replacement pattern, we use backreferences to restore the characters captured with the parentheses (capturing groups).