1 files changed, 164 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/internal/modindex/modindex.go b/vendor/golang.org/x/tools/internal/modindex/modindex.go
new file mode 100644
index 000000000..355a53e71
--- /dev/null
+++ b/vendor/golang.org/x/tools/internal/modindex/modindex.go
@@ -0,0 +1,164 @@
+// Copyright 2024 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 modindex contains code for building and searching an index to
+// the Go module cache. The directory containing the index, returned by
+// IndexDir(), contains a file index-name-<ver> that contains the name
+// of the current index. We believe writing that short file is atomic.
+// ReadIndex reads that file to get the file name of the index.
+// WriteIndex writes an index with a unique name and then
+// writes that name into a new version of index-name-<ver>.
+// (<ver> stands for the CurrentVersion of the index format.)
+package modindex
+
+import (
+	"path/filepath"
+	"slices"
+	"strings"
+	"time"
+
+	"golang.org/x/mod/semver"
+)
+
+// Create always creates a new index for the go module cache that is in cachedir.
+func Create(cachedir string) error {
+	_, err := indexModCache(cachedir, true)
+	return err
+}
+
+// Update the index for the go module cache that is in cachedir,
+// If there is no existing index it will build one.
+// If there are changed directories since the last index, it will
+// write a new one and return true. Otherwise it returns false.
+func Update(cachedir string) (bool, error) {
+	return indexModCache(cachedir, false)
+}
+
+// indexModCache writes an index current as of when it is called.
+// If clear is true the index is constructed from all of GOMODCACHE
+// otherwise the index is constructed from the last previous index
+// and the updates to the cache. It returns true if it wrote an index,
+// false otherwise.
+func indexModCache(cachedir string, clear bool) (bool, error) {
+	cachedir, err := filepath.Abs(cachedir)
+	if err != nil {
+		return false, err
+	}
+	cd := Abspath(cachedir)
+	future := time.Now().Add(24 * time.Hour) // safely in the future
+	ok, err := modindexTimed(future, cd, clear)
+	if err != nil {
+		return false, err
+	}
+	return ok, nil
+}
+
+// modindexTimed writes an index current as of onlyBefore.
+// If clear is true the index is constructed from all of GOMODCACHE
+// otherwise the index is constructed from the last previous index
+// and all the updates to the cache before onlyBefore.
+// It returns true if it wrote a new index, false if it wrote nothing.
+func modindexTimed(onlyBefore time.Time, cachedir Abspath, clear bool) (bool, error) {
+	var curIndex *Index
+	if !clear {
+		var err error
+		curIndex, err = ReadIndex(string(cachedir))
+		if clear && err != nil {
+			return false, err
+		}
+		// TODO(pjw): check that most of those directories still exist
+	}
+	cfg := &work{
+		onlyBefore: onlyBefore,
+		oldIndex:   curIndex,
+		cacheDir:   cachedir,
+	}
+	if curIndex != nil {
+		cfg.onlyAfter = curIndex.Changed
+	}
+	if err := cfg.buildIndex(); err != nil {
+		return false, err
+	}
+	if len(cfg.newIndex.Entries) == 0 && curIndex != nil {
+		// no changes from existing curIndex, don't write a new index
+		return false, nil
+	}
+	if err := cfg.writeIndex(); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+type work struct {
+	onlyBefore time.Time // do not use directories later than this
+	onlyAfter  time.Time // only interested in directories after this
+	// directories from before onlyAfter come from oldIndex
+	oldIndex *Index
+	newIndex *Index
+	cacheDir Abspath
+}
+
+func (w *work) buildIndex() error {
+	// The effective date of the new index should be at least
+	// slightly earlier than when the directories are scanned
+	// so set it now.
+	w.newIndex = &Index{Changed: time.Now(), Cachedir: w.cacheDir}
+	dirs := findDirs(string(w.cacheDir), w.onlyAfter, w.onlyBefore)
+	if len(dirs) == 0 {
+		return nil
+	}
+	newdirs, err := byImportPath(dirs)
+	if err != nil {
+		return err
+	}
+	// for each import path it might occur only in newdirs,
+	// only in w.oldIndex, or in both.
+	// If it occurs in both, use the semantically later one
+	if w.oldIndex != nil {
+		for _, e := range w.oldIndex.Entries {
+			found, ok := newdirs[e.ImportPath]
+			if !ok {
+				w.newIndex.Entries = append(w.newIndex.Entries, e)
+				continue // use this one, there is no new one
+			}
+			if semver.Compare(found[0].version, e.Version) > 0 {
+				// use the new one
+			} else {
+				// use the old one, forget the new one
+				w.newIndex.Entries = append(w.newIndex.Entries, e)
+				delete(newdirs, e.ImportPath)
+			}
+		}
+	}
+	// get symbol information for all the new diredtories
+	getSymbols(w.cacheDir, newdirs)
+	// assemble the new index entries
+	for k, v := range newdirs {
+		d := v[0]
+		pkg, names := processSyms(d.syms)
+		if pkg == "" {
+			continue // PJW: does this ever happen?
+		}
+		entry := Entry{
+			PkgName:    pkg,
+			Dir:        d.path,
+			ImportPath: k,
+			Version:    d.version,
+			Names:      names,
+		}
+		w.newIndex.Entries = append(w.newIndex.Entries, entry)
+	}
+	// sort the entries in the new index
+	slices.SortFunc(w.newIndex.Entries, func(l, r Entry) int {
+		if n := strings.Compare(l.PkgName, r.PkgName); n != 0 {
+			return n
+		}
+		return strings.Compare(l.ImportPath, r.ImportPath)
+	})
+	return nil
+}
+
+func (w *work) writeIndex() error {
+	return writeIndex(w.cacheDir, w.newIndex)
+}