77 lines
2.7 KiB
Go
77 lines
2.7 KiB
Go
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// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package match provides functions for performing filepath [?,*,**] wildcard
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// matching.
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package match
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import (
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"fmt"
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"regexp"
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"strings"
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)
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// Test is the match predicate returned by New.
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type Test func(path string) bool
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// New returns a Test function that returns true iff the path matches the
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// provided pattern.
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//
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// pattern uses forward-slashes for directory separators '/', and may use the
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// following wildcards:
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// ? - matches any single non-separator character
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// * - matches any sequence of non-separator characters
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// ** - matches any sequence of characters including separators
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func New(pattern string) (Test, error) {
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// Transform pattern into a regex by replacing the uses of `?`, `*`, `**`
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// with corresponding regex patterns.
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// As the pattern may contain other regex sequences, the string has to be
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// escaped. So:
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// a) Replace the patterns of `?`, `*`, `**` with unique placeholder tokens.
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// b) Escape the expression so that other sequences don't confuse the regex
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// parser.
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// c) Replace the placeholder tokens with the corresponding regex tokens.
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// Temporary placeholder tokens
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const (
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starstar = "••"
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star = "•"
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questionmark = "¿"
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)
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// Check pattern doesn't contain any of our placeholder tokens
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for _, r := range []rune{'•', '¿'} {
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if strings.ContainsRune(pattern, r) {
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return nil, fmt.Errorf("Pattern must not contain '%c'", r)
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}
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}
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// Replace **, * and ? with placeholder tokens
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subbed := pattern
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subbed = strings.ReplaceAll(subbed, "**", starstar)
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subbed = strings.ReplaceAll(subbed, "*", star)
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subbed = strings.ReplaceAll(subbed, "?", questionmark)
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// Escape any remaining regex characters
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escaped := regexp.QuoteMeta(subbed)
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// Insert regex matchers for the substituted tokens
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regex := "^" + escaped + "$"
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regex = strings.ReplaceAll(regex, starstar, ".*")
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regex = strings.ReplaceAll(regex, star, "[^/]*")
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regex = strings.ReplaceAll(regex, questionmark, "[^/]")
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re, err := regexp.Compile(regex)
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if err != nil {
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return nil, fmt.Errorf(`Failed to compile regex "%v" for pattern "%v": %w`, regex, pattern, err)
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}
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return re.MatchString, nil
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}
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