| // Copyright 2022 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package scan |
| |
| import ( |
| "fmt" |
| "strings" |
| |
| "golang.org/x/mod/semver" |
| ) |
| |
| // Support functions for standard library packages. |
| // These are copied from the internal/stdlib package in the pkgsite repo. |
| |
| // semverToGoTag returns the Go standard library repository tag corresponding |
| // to semver, a version string without the initial "v". |
| // Go tags differ from standard semantic versions in a few ways, |
| // such as beginning with "go" instead of "v". |
| func semverToGoTag(v string) string { |
| if strings.HasPrefix(v, "v0.0.0") { |
| return "master" |
| } |
| // Special case: v1.0.0 => go1. |
| if v == "v1.0.0" { |
| return "go1" |
| } |
| if !semver.IsValid(v) { |
| return fmt.Sprintf("<!%s:invalid semver>", v) |
| } |
| goVersion := semver.Canonical(v) |
| prerelease := semver.Prerelease(goVersion) |
| versionWithoutPrerelease := strings.TrimSuffix(goVersion, prerelease) |
| patch := strings.TrimPrefix(versionWithoutPrerelease, semver.MajorMinor(goVersion)+".") |
| if patch == "0" { |
| versionWithoutPrerelease = strings.TrimSuffix(versionWithoutPrerelease, ".0") |
| } |
| goVersion = fmt.Sprintf("go%s", strings.TrimPrefix(versionWithoutPrerelease, "v")) |
| if prerelease != "" { |
| // Go prereleases look like "beta1" instead of "beta.1". |
| // "beta1" is bad for sorting (since beta10 comes before beta9), so |
| // require the dot form. |
| i := finalDigitsIndex(prerelease) |
| if i >= 1 { |
| if prerelease[i-1] != '.' { |
| return fmt.Sprintf("<!%s:final digits in a prerelease must follow a period>", v) |
| } |
| // Remove the dot. |
| prerelease = prerelease[:i-1] + prerelease[i:] |
| } |
| goVersion += strings.TrimPrefix(prerelease, "-") |
| } |
| return goVersion |
| } |
| |
| // finalDigitsIndex returns the index of the first digit in the sequence of digits ending s. |
| // If s doesn't end in digits, it returns -1. |
| func finalDigitsIndex(s string) int { |
| // Assume ASCII (since the semver package does anyway). |
| var i int |
| for i = len(s) - 1; i >= 0; i-- { |
| if s[i] < '0' || s[i] > '9' { |
| break |
| } |
| } |
| if i == len(s)-1 { |
| return -1 |
| } |
| return i + 1 |
| } |