251 lines
8.4 KiB
Go
251 lines
8.4 KiB
Go
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Pseudo-versions
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//
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// Code authors are expected to tag the revisions they want users to use,
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// including prereleases. However, not all authors tag versions at all,
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// and not all commits a user might want to try will have tags.
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// A pseudo-version is a version with a special form that allows us to
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// address an untagged commit and order that version with respect to
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// other versions we might encounter.
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//
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// A pseudo-version takes one of the general forms:
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//
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// (1) vX.0.0-yyyymmddhhmmss-abcdef123456
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// (2) vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456
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// (3) vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456+incompatible
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// (4) vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456
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// (5) vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456+incompatible
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//
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// If there is no recently tagged version with the right major version vX,
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// then form (1) is used, creating a space of pseudo-versions at the bottom
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// of the vX version range, less than any tagged version, including the unlikely v0.0.0.
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//
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// If the most recent tagged version before the target commit is vX.Y.Z or vX.Y.Z+incompatible,
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// then the pseudo-version uses form (2) or (3), making it a prerelease for the next
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// possible semantic version after vX.Y.Z. The leading 0 segment in the prerelease string
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// ensures that the pseudo-version compares less than possible future explicit prereleases
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// like vX.Y.(Z+1)-rc1 or vX.Y.(Z+1)-1.
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//
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// If the most recent tagged version before the target commit is vX.Y.Z-pre or vX.Y.Z-pre+incompatible,
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// then the pseudo-version uses form (4) or (5), making it a slightly later prerelease.
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package module
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import (
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"errors"
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"fmt"
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"strings"
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"time"
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"golang.org/x/mod/internal/lazyregexp"
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"golang.org/x/mod/semver"
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)
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var pseudoVersionRE = lazyregexp.New(`^v[0-9]+\.(0\.0-|\d+\.\d+-([^+]*\.)?0\.)\d{14}-[A-Za-z0-9]+(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$`)
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const PseudoVersionTimestampFormat = "20060102150405"
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// PseudoVersion returns a pseudo-version for the given major version ("v1")
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// preexisting older tagged version ("" or "v1.2.3" or "v1.2.3-pre"), revision time,
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// and revision identifier (usually a 12-byte commit hash prefix).
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func PseudoVersion(major, older string, t time.Time, rev string) string {
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if major == "" {
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major = "v0"
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}
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segment := fmt.Sprintf("%s-%s", t.UTC().Format(PseudoVersionTimestampFormat), rev)
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build := semver.Build(older)
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older = semver.Canonical(older)
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if older == "" {
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return major + ".0.0-" + segment // form (1)
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}
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if semver.Prerelease(older) != "" {
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return older + ".0." + segment + build // form (4), (5)
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}
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// Form (2), (3).
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// Extract patch from vMAJOR.MINOR.PATCH
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i := strings.LastIndex(older, ".") + 1
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v, patch := older[:i], older[i:]
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// Reassemble.
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return v + incDecimal(patch) + "-0." + segment + build
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}
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// ZeroPseudoVersion returns a pseudo-version with a zero timestamp and
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// revision, which may be used as a placeholder.
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func ZeroPseudoVersion(major string) string {
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return PseudoVersion(major, "", time.Time{}, "000000000000")
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}
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// incDecimal returns the decimal string incremented by 1.
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func incDecimal(decimal string) string {
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// Scan right to left turning 9s to 0s until you find a digit to increment.
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digits := []byte(decimal)
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i := len(digits) - 1
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for ; i >= 0 && digits[i] == '9'; i-- {
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digits[i] = '0'
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}
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if i >= 0 {
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digits[i]++
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} else {
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// digits is all zeros
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digits[0] = '1'
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digits = append(digits, '0')
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}
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return string(digits)
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}
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// decDecimal returns the decimal string decremented by 1, or the empty string
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// if the decimal is all zeroes.
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func decDecimal(decimal string) string {
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// Scan right to left turning 0s to 9s until you find a digit to decrement.
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digits := []byte(decimal)
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i := len(digits) - 1
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for ; i >= 0 && digits[i] == '0'; i-- {
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digits[i] = '9'
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}
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if i < 0 {
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// decimal is all zeros
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return ""
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}
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if i == 0 && digits[i] == '1' && len(digits) > 1 {
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digits = digits[1:]
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} else {
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digits[i]--
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}
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return string(digits)
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}
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// IsPseudoVersion reports whether v is a pseudo-version.
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func IsPseudoVersion(v string) bool {
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return strings.Count(v, "-") >= 2 && semver.IsValid(v) && pseudoVersionRE.MatchString(v)
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}
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// IsZeroPseudoVersion returns whether v is a pseudo-version with a zero base,
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// timestamp, and revision, as returned by ZeroPseudoVersion.
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func IsZeroPseudoVersion(v string) bool {
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return v == ZeroPseudoVersion(semver.Major(v))
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}
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// PseudoVersionTime returns the time stamp of the pseudo-version v.
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// It returns an error if v is not a pseudo-version or if the time stamp
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// embedded in the pseudo-version is not a valid time.
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func PseudoVersionTime(v string) (time.Time, error) {
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_, timestamp, _, _, err := parsePseudoVersion(v)
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if err != nil {
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return time.Time{}, err
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}
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t, err := time.Parse("20060102150405", timestamp)
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if err != nil {
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return time.Time{}, &InvalidVersionError{
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Version: v,
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Pseudo: true,
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Err: fmt.Errorf("malformed time %q", timestamp),
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}
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}
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return t, nil
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}
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// PseudoVersionRev returns the revision identifier of the pseudo-version v.
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// It returns an error if v is not a pseudo-version.
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func PseudoVersionRev(v string) (rev string, err error) {
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_, _, rev, _, err = parsePseudoVersion(v)
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return
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}
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// PseudoVersionBase returns the canonical parent version, if any, upon which
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// the pseudo-version v is based.
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//
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// If v has no parent version (that is, if it is "vX.0.0-[…]"),
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// PseudoVersionBase returns the empty string and a nil error.
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func PseudoVersionBase(v string) (string, error) {
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base, _, _, build, err := parsePseudoVersion(v)
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if err != nil {
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return "", err
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}
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switch pre := semver.Prerelease(base); pre {
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case "":
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// vX.0.0-yyyymmddhhmmss-abcdef123456 → ""
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if build != "" {
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// Pseudo-versions of the form vX.0.0-yyyymmddhhmmss-abcdef123456+incompatible
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// are nonsensical: the "vX.0.0-" prefix implies that there is no parent tag,
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// but the "+incompatible" suffix implies that the major version of
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// the parent tag is not compatible with the module's import path.
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//
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// There are a few such entries in the index generated by proxy.golang.org,
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// but we believe those entries were generated by the proxy itself.
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return "", &InvalidVersionError{
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Version: v,
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Pseudo: true,
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Err: fmt.Errorf("lacks base version, but has build metadata %q", build),
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}
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}
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return "", nil
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case "-0":
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// vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456 → vX.Y.Z
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// vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456+incompatible → vX.Y.Z+incompatible
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base = strings.TrimSuffix(base, pre)
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i := strings.LastIndexByte(base, '.')
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if i < 0 {
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panic("base from parsePseudoVersion missing patch number: " + base)
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}
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patch := decDecimal(base[i+1:])
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if patch == "" {
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// vX.0.0-0 is invalid, but has been observed in the wild in the index
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// generated by requests to proxy.golang.org.
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//
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// NOTE(bcmills): I cannot find a historical bug that accounts for
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// pseudo-versions of this form, nor have I seen such versions in any
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// actual go.mod files. If we find actual examples of this form and a
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// reasonable theory of how they came into existence, it seems fine to
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// treat them as equivalent to vX.0.0 (especially since the invalid
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// pseudo-versions have lower precedence than the real ones). For now, we
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// reject them.
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return "", &InvalidVersionError{
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Version: v,
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Pseudo: true,
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Err: fmt.Errorf("version before %s would have negative patch number", base),
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}
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}
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return base[:i+1] + patch + build, nil
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default:
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// vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456 → vX.Y.Z-pre
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// vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456+incompatible → vX.Y.Z-pre+incompatible
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if !strings.HasSuffix(base, ".0") {
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panic(`base from parsePseudoVersion missing ".0" before date: ` + base)
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}
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return strings.TrimSuffix(base, ".0") + build, nil
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}
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}
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var errPseudoSyntax = errors.New("syntax error")
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func parsePseudoVersion(v string) (base, timestamp, rev, build string, err error) {
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if !IsPseudoVersion(v) {
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return "", "", "", "", &InvalidVersionError{
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Version: v,
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Pseudo: true,
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Err: errPseudoSyntax,
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}
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}
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build = semver.Build(v)
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v = strings.TrimSuffix(v, build)
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j := strings.LastIndex(v, "-")
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v, rev = v[:j], v[j+1:]
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i := strings.LastIndex(v, "-")
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if j := strings.LastIndex(v, "."); j > i {
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base = v[:j] // "vX.Y.Z-pre.0" or "vX.Y.(Z+1)-0"
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timestamp = v[j+1:]
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} else {
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base = v[:i] // "vX.0.0"
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timestamp = v[i+1:]
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}
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return base, timestamp, rev, build, nil
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}
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