matcher.go

// Copyright 2022 Twitter, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

func matchContexts(in []string, f []filter) []string {
	var additive, subtractive []filter
	for _, ff := range f {
		if ff.additive() {
			additive = append(additive, ff)
		} else {
			subtractive = append(subtractive, ff)
		}
	}

	var out []string
	for _, ctx := range in {
		add, remove := len(additive) == 0, false

		for _, af := range additive {
			if af.match(ctx) {
				add = true
				break
			}
		}

		for _, sf := range subtractive {
			if sf.match(ctx) {
				remove = true
				break
			}
		}

		if add && !remove {
			out = append(out, ctx)
		}
	}
	return out
}