Filter out some scss partials to apply postcss on them

[ivangretsky]

Good day!

I am building my styles from SCSS with a single entry point main.scss. SCSS partials are included via @import. I need to apply some postcss transformations to some partials after the got compiled to css. As I do not know exactly in which order the transformations in fact happen during the sass compilation process I am not sure if it is even possible. I am not yet skillful enough to debug it myself)) Please give me an advice how to solve this.

Below is my .gulpfile so you can understand what I am after more clear:

var gulp = require('gulp');
var postcss = require('gulp-postcss');
var prefixer = require('postcss-prefixer');
var sass = require('gulp-sass');
var filter = require('gulp-filter');

gulp.task('prefix', function () {
    var plugins = [
        prefixer({
            prefix: 'PREFIXXX-',
            ignore: []
        })
    ];
    
    var f = filter('*.bootstrap.scss', {restore: true});

    // return gulp.src('./static_src/styles/utilities/**')
    return gulp.src('static_src/styles/main.scss', )
        .pipe(sass().on('error', sass.logError))
        .pipe(f)
            .pipe(postcss(plugins))
        .pipe(f.restore)
        .pipe(gulp.dest('./dest'));
});

gulp.task('default', ['prefix']);

[sindresorhus]

Probably better to ask on Stack Overflow.