1 files changed, 145 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/internal/modindex/lookup.go b/vendor/golang.org/x/tools/internal/modindex/lookup.go
new file mode 100644
index 000000000..29d4e3d7a
--- /dev/null
+++ b/vendor/golang.org/x/tools/internal/modindex/lookup.go
@@ -0,0 +1,145 @@
+// 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
+
+import (
+	"slices"
+	"strconv"
+	"strings"
+)
+
+type Candidate struct {
+	PkgName    string
+	Name       string
+	Dir        string
+	ImportPath string
+	Type       LexType
+	// information for Funcs
+	Results int16   // how many results
+	Sig     []Field // arg names and types
+}
+
+type Field struct {
+	Arg, Type string
+}
+
+type LexType int8
+
+const (
+	Const LexType = iota
+	Var
+	Type
+	Func
+)
+
+// Lookup finds all the symbols in the index with the given PkgName and name.
+// If prefix is true, it finds all of these with name as a prefix.
+func (ix *Index) Lookup(pkg, name string, prefix bool) []Candidate {
+	loc, ok := slices.BinarySearchFunc(ix.Entries, pkg, func(e Entry, pkg string) int {
+		return strings.Compare(e.PkgName, pkg)
+	})
+	if !ok {
+		return nil // didn't find the package
+	}
+	var ans []Candidate
+	// loc is the first entry for this package name, but there may be severeal
+	for i := loc; i < len(ix.Entries); i++ {
+		e := ix.Entries[i]
+		if e.PkgName != pkg {
+			break // end of sorted package names
+		}
+		nloc, ok := slices.BinarySearchFunc(e.Names, name, func(s string, name string) int {
+			if strings.HasPrefix(s, name) {
+				return 0
+			}
+			if s < name {
+				return -1
+			}
+			return 1
+		})
+		if !ok {
+			continue // didn't find the name, nor any symbols with name as a prefix
+		}
+		for j := nloc; j < len(e.Names); j++ {
+			nstr := e.Names[j]
+			// benchmarks show this makes a difference when there are a lot of Possibilities
+			flds := fastSplit(nstr)
+			if !(flds[0] == name || prefix && strings.HasPrefix(flds[0], name)) {
+				// past range of matching Names
+				break
+			}
+			if len(flds) < 2 {
+				continue // should never happen
+			}
+			px := Candidate{
+				PkgName:    pkg,
+				Name:       flds[0],
+				Dir:        string(e.Dir),
+				ImportPath: e.ImportPath,
+				Type:       asLexType(flds[1][0]),
+			}
+			if flds[1] == "F" {
+				n, err := strconv.Atoi(flds[2])
+				if err != nil {
+					continue // should never happen
+				}
+				px.Results = int16(n)
+				if len(flds) >= 4 {
+					sig := strings.Split(flds[3], " ")
+					for i := 0; i < len(sig); i++ {
+						// $ cannot otherwise occur. removing the spaces
+						// almost works, but for chan struct{}, e.g.
+						sig[i] = strings.Replace(sig[i], "$", " ", -1)
+					}
+					px.Sig = toFields(sig)
+				}
+			}
+			ans = append(ans, px)
+		}
+	}
+	return ans
+}
+
+func toFields(sig []string) []Field {
+	ans := make([]Field, len(sig)/2)
+	for i := 0; i < len(ans); i++ {
+		ans[i] = Field{Arg: sig[2*i], Type: sig[2*i+1]}
+	}
+	return ans
+}
+
+// benchmarks show this is measurably better than strings.Split
+func fastSplit(x string) []string {
+	ans := make([]string, 0, 4)
+	nxt := 0
+	start := 0
+	for i := 0; i < len(x); i++ {
+		if x[i] != ' ' {
+			continue
+		}
+		ans = append(ans, x[start:i])
+		nxt++
+		start = i + 1
+		if nxt >= 3 {
+			break
+		}
+	}
+	ans = append(ans, x[start:])
+	return ans
+}
+
+func asLexType(c byte) LexType {
+	switch c {
+	case 'C':
+		return Const
+	case 'V':
+		return Var
+	case 'T':
+		return Type
+	case 'F':
+		return Func
+	}
+	return -1
+}