208 lines
5.7 KiB
Go
208 lines
5.7 KiB
Go
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/*
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* Minio Cloud Storage, (C) 2018 Minio, Inc.
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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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* http://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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*/
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package ellipses
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import (
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"errors"
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"fmt"
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"regexp"
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"strconv"
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"strings"
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)
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var (
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// Regex to extract ellipses syntax inputs.
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regexpEllipses = regexp.MustCompile(`(.*)({[0-9]*\.\.\.[0-9]*})(.*)`)
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// Ellipses constants
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openBraces = "{"
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closeBraces = "}"
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ellipses = "..."
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)
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// Parses an ellipses range pattern of following style
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// `{1...64}`
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// `{33...64}`
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func parseEllipsesRange(pattern string) (seq []string, err error) {
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if strings.Index(pattern, openBraces) == -1 {
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return nil, errors.New("Invalid argument")
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}
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if strings.Index(pattern, closeBraces) == -1 {
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return nil, errors.New("Invalid argument")
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}
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pattern = strings.TrimPrefix(pattern, openBraces)
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pattern = strings.TrimSuffix(pattern, closeBraces)
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ellipsesRange := strings.Split(pattern, ellipses)
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if len(ellipsesRange) != 2 {
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return nil, errors.New("Invalid argument")
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}
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var start, end uint64
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if start, err = strconv.ParseUint(ellipsesRange[0], 10, 64); err != nil {
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return nil, err
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}
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if end, err = strconv.ParseUint(ellipsesRange[1], 10, 64); err != nil {
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return nil, err
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}
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if start > end {
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return nil, fmt.Errorf("Incorrect range start %d cannot be bigger than end %d", start, end)
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}
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for i := start; i <= end; i++ {
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if strings.HasPrefix(ellipsesRange[0], "0") && len(ellipsesRange[0]) > 1 || strings.HasPrefix(ellipsesRange[1], "0") {
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seq = append(seq, fmt.Sprintf(fmt.Sprintf("%%0%dd", len(ellipsesRange[1])), i))
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} else {
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seq = append(seq, fmt.Sprintf("%d", i))
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}
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}
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return seq, nil
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}
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// Pattern - ellipses pattern, describes the range and also the
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// associated prefix and suffixes.
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type Pattern struct {
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Prefix string
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Suffix string
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Seq []string
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}
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// argExpander - recursively expands labels into its respective forms.
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func argExpander(labels [][]string) (out [][]string) {
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if len(labels) == 1 {
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for _, v := range labels[0] {
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out = append(out, []string{v})
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}
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return out
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}
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for _, lbl := range labels[0] {
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rs := argExpander(labels[1:])
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for _, rlbls := range rs {
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r := append(rlbls, []string{lbl}...)
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out = append(out, r)
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}
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}
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return out
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}
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// ArgPattern contains a list of patterns provided in the input.
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type ArgPattern []Pattern
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// Expand - expands all the ellipses patterns in
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// the given argument.
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func (a ArgPattern) Expand() [][]string {
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labels := make([][]string, len(a))
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for i := range labels {
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labels[i] = a[i].Expand()
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}
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return argExpander(labels)
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}
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// Expand - expands a ellipses pattern.
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func (p Pattern) Expand() []string {
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var labels []string
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for i := range p.Seq {
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switch {
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case p.Prefix != "" && p.Suffix == "":
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labels = append(labels, fmt.Sprintf("%s%s", p.Prefix, p.Seq[i]))
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case p.Suffix != "" && p.Prefix == "":
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labels = append(labels, fmt.Sprintf("%s%s", p.Seq[i], p.Suffix))
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case p.Suffix == "" && p.Prefix == "":
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labels = append(labels, fmt.Sprintf("%s", p.Seq[i]))
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default:
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labels = append(labels, fmt.Sprintf("%s%s%s", p.Prefix, p.Seq[i], p.Suffix))
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}
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}
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return labels
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}
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// HasEllipses - returns true if input arg has ellipses type pattern.
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func HasEllipses(args ...string) bool {
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var ok = true
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for _, arg := range args {
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ok = ok && (strings.Count(arg, ellipses) > 0 || (strings.Count(arg, openBraces) > 0 && strings.Count(arg, closeBraces) > 0))
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}
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return ok
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}
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// ErrInvalidEllipsesFormatFn error returned when invalid ellipses format is detected.
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var ErrInvalidEllipsesFormatFn = func(arg string) error {
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return fmt.Errorf("Invalid ellipsis format in (%s), Ellipsis range must be provided in format {N...M} where N and M are positive integers, M must be greater than N, with an allowed minimum range of 4", arg)
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}
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// FindEllipsesPatterns - finds all ellipses patterns, recursively and parses the ranges numerically.
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func FindEllipsesPatterns(arg string) (ArgPattern, error) {
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var patterns []Pattern
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parts := regexpEllipses.FindStringSubmatch(arg)
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if len(parts) == 0 {
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// We throw an error if arg doesn't have any recognizable ellipses pattern.
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return nil, ErrInvalidEllipsesFormatFn(arg)
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}
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parts = parts[1:]
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patternFound := regexpEllipses.MatchString(parts[0])
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for patternFound {
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seq, err := parseEllipsesRange(parts[1])
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if err != nil {
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return patterns, err
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}
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patterns = append(patterns, Pattern{
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Prefix: "",
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Suffix: parts[2],
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Seq: seq,
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})
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parts = regexpEllipses.FindStringSubmatch(parts[0])
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if len(parts) > 0 {
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parts = parts[1:]
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patternFound = HasEllipses(parts[0])
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continue
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}
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break
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}
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if len(parts) > 0 {
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seq, err := parseEllipsesRange(parts[1])
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if err != nil {
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return patterns, err
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}
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patterns = append(patterns, Pattern{
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Prefix: parts[0],
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Suffix: parts[2],
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Seq: seq,
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})
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}
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// Check if any of the prefix or suffixes now have flower braces
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// left over, in such a case we generally think that there is
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// perhaps a typo in users input and error out accordingly.
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for _, pattern := range patterns {
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if strings.Count(pattern.Prefix, openBraces) > 0 || strings.Count(pattern.Prefix, closeBraces) > 0 {
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return nil, ErrInvalidEllipsesFormatFn(arg)
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}
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if strings.Count(pattern.Suffix, openBraces) > 0 || strings.Count(pattern.Suffix, closeBraces) > 0 {
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return nil, ErrInvalidEllipsesFormatFn(arg)
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}
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}
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return patterns, nil
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}
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