[SOLVED] Replace with regex in Golang

Replace with regex in Golang

I've tried to use the regexp package to replace text :

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

I could not replace "products" without replace other words like "products_list"; and Golang has not a function like re.ReplaceAllStringSubmatch to replace with submatch (there's just FindAllStringSubmatch). I've used re.ReplaceAllString to replace "products" with .

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

But I need this result:

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

Solution

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).