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Copy pathellipses.go
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207 lines (182 loc) · 5.73 KB
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/*
* Minio Cloud Storage, (C) 2018 Minio, 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 ellipses
import (
"errors"
"fmt"
"regexp"
"strconv"
"strings"
)
var (
// Regex to extract ellipses syntax inputs.
regexpEllipses = regexp.MustCompile(`(.*)({[0-9]*\.\.\.[0-9]*})(.*)`)
// Ellipses constants
openBraces = "{"
closeBraces = "}"
ellipses = "..."
)
// Parses an ellipses range pattern of following style
// `{1...64}`
// `{33...64}`
func parseEllipsesRange(pattern string) (seq []string, err error) {
if strings.Index(pattern, openBraces) == -1 {
return nil, errors.New("Invalid argument")
}
if strings.Index(pattern, closeBraces) == -1 {
return nil, errors.New("Invalid argument")
}
pattern = strings.TrimPrefix(pattern, openBraces)
pattern = strings.TrimSuffix(pattern, closeBraces)
ellipsesRange := strings.Split(pattern, ellipses)
if len(ellipsesRange) != 2 {
return nil, errors.New("Invalid argument")
}
var start, end uint64
if start, err = strconv.ParseUint(ellipsesRange[0], 10, 64); err != nil {
return nil, err
}
if end, err = strconv.ParseUint(ellipsesRange[1], 10, 64); err != nil {
return nil, err
}
if start > end {
return nil, fmt.Errorf("Incorrect range start %d cannot be bigger than end %d", start, end)
}
for i := start; i <= end; i++ {
if strings.HasPrefix(ellipsesRange[0], "0") && len(ellipsesRange[0]) > 1 || strings.HasPrefix(ellipsesRange[1], "0") {
seq = append(seq, fmt.Sprintf(fmt.Sprintf("%%0%dd", len(ellipsesRange[1])), i))
} else {
seq = append(seq, fmt.Sprintf("%d", i))
}
}
return seq, nil
}
// Pattern - ellipses pattern, describes the range and also the
// associated prefix and suffixes.
type Pattern struct {
Prefix string
Suffix string
Seq []string
}
// argExpander - recursively expands labels into its respective forms.
func argExpander(labels [][]string) (out [][]string) {
if len(labels) == 1 {
for _, v := range labels[0] {
out = append(out, []string{v})
}
return out
}
for _, lbl := range labels[0] {
rs := argExpander(labels[1:])
for _, rlbls := range rs {
r := append(rlbls, []string{lbl}...)
out = append(out, r)
}
}
return out
}
// ArgPattern contains a list of patterns provided in the input.
type ArgPattern []Pattern
// Expand - expands all the ellipses patterns in
// the given argument.
func (a ArgPattern) Expand() [][]string {
labels := make([][]string, len(a))
for i := range labels {
labels[i] = a[i].Expand()
}
return argExpander(labels)
}
// Expand - expands a ellipses pattern.
func (p Pattern) Expand() []string {
var labels []string
for i := range p.Seq {
switch {
case p.Prefix != "" && p.Suffix == "":
labels = append(labels, fmt.Sprintf("%s%s", p.Prefix, p.Seq[i]))
case p.Suffix != "" && p.Prefix == "":
labels = append(labels, fmt.Sprintf("%s%s", p.Seq[i], p.Suffix))
case p.Suffix == "" && p.Prefix == "":
labels = append(labels, fmt.Sprintf("%s", p.Seq[i]))
default:
labels = append(labels, fmt.Sprintf("%s%s%s", p.Prefix, p.Seq[i], p.Suffix))
}
}
return labels
}
// HasEllipses - returns true if input arg has ellipses type pattern.
func HasEllipses(args ...string) bool {
var ok = true
for _, arg := range args {
ok = ok && (strings.Count(arg, ellipses) > 0 || (strings.Count(arg, openBraces) > 0 && strings.Count(arg, closeBraces) > 0))
}
return ok
}
// ErrInvalidEllipsesFormatFn error returned when invalid ellipses format is detected.
var ErrInvalidEllipsesFormatFn = func(arg string) error {
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)
}
// FindEllipsesPatterns - finds all ellipses patterns, recursively and parses the ranges numerically.
func FindEllipsesPatterns(arg string) (ArgPattern, error) {
var patterns []Pattern
parts := regexpEllipses.FindStringSubmatch(arg)
if len(parts) == 0 {
// We throw an error if arg doesn't have any recognizable ellipses pattern.
return nil, ErrInvalidEllipsesFormatFn(arg)
}
parts = parts[1:]
patternFound := regexpEllipses.MatchString(parts[0])
for patternFound {
seq, err := parseEllipsesRange(parts[1])
if err != nil {
return patterns, err
}
patterns = append(patterns, Pattern{
Prefix: "",
Suffix: parts[2],
Seq: seq,
})
parts = regexpEllipses.FindStringSubmatch(parts[0])
if len(parts) > 0 {
parts = parts[1:]
patternFound = HasEllipses(parts[0])
continue
}
break
}
if len(parts) > 0 {
seq, err := parseEllipsesRange(parts[1])
if err != nil {
return patterns, err
}
patterns = append(patterns, Pattern{
Prefix: parts[0],
Suffix: parts[2],
Seq: seq,
})
}
// Check if any of the prefix or suffixes now have flower braces
// left over, in such a case we generally think that there is
// perhaps a typo in users input and error out accordingly.
for _, pattern := range patterns {
if strings.Count(pattern.Prefix, openBraces) > 0 || strings.Count(pattern.Prefix, closeBraces) > 0 {
return nil, ErrInvalidEllipsesFormatFn(arg)
}
if strings.Count(pattern.Suffix, openBraces) > 0 || strings.Count(pattern.Suffix, closeBraces) > 0 {
return nil, ErrInvalidEllipsesFormatFn(arg)
}
}
return patterns, nil
}