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// 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 (
"fmt"
"go/ast"
"go/parser"
"go/token"
"go/types"
"os"
"path/filepath"
"slices"
"strings"
"golang.org/x/sync/errgroup"
)
// The name of a symbol contains information about the symbol:
// <name> T for types
// <name> C for consts
// <name> V for vars
// and for funcs: <name> F <num of return values> (<arg-name> <arg-type>)*
// any spaces in <arg-type> are replaced by $s so that the fields
// of the name are space separated
type symbol struct {
pkg string // name of the symbols's package
name string // declared name
kind string // T, C, V, or F
sig string // signature information, for F
}
// find the symbols for the best directories
func getSymbols(cd Abspath, dirs map[string][]*directory) {
var g errgroup.Group
g.SetLimit(-1) // maybe throttle this some day
for _, vv := range dirs {
// throttling some day?
d := vv[0]
g.Go(func() error {
thedir := filepath.Join(string(cd), string(d.path))
mode := parser.SkipObjectResolution
fi, err := os.ReadDir(thedir)
if err != nil {
return nil // log this someday?
}
for _, fx := range fi {
if !strings.HasSuffix(fx.Name(), ".go") || strings.HasSuffix(fx.Name(), "_test.go") {
continue
}
fname := filepath.Join(thedir, fx.Name())
tr, err := parser.ParseFile(token.NewFileSet(), fname, nil, mode)
if err != nil {
continue // ignore errors, someday log them?
}
d.syms = append(d.syms, getFileExports(tr)...)
}
return nil
})
}
g.Wait()
}
func getFileExports(f *ast.File) []symbol {
pkg := f.Name.Name
if pkg == "main" {
return nil
}
var ans []symbol
// should we look for //go:build ignore?
for _, decl := range f.Decls {
switch decl := decl.(type) {
case *ast.FuncDecl:
if decl.Recv != nil {
// ignore methods, as we are completing package selections
continue
}
name := decl.Name.Name
dtype := decl.Type
// not looking at dtype.TypeParams. That is, treating
// generic functions just like non-generic ones.
sig := dtype.Params
kind := "F"
result := []string{fmt.Sprintf("%d", dtype.Results.NumFields())}
for _, x := range sig.List {
// This code creates a string representing the type.
// TODO(pjw): it may be fragile:
// 1. x.Type could be nil, perhaps in ill-formed code
// 2. ExprString might someday change incompatibly to
// include struct tags, which can be arbitrary strings
if x.Type == nil {
// Can this happen without a parse error? (Files with parse
// errors are ignored in getSymbols)
continue // maybe report this someday
}
tp := types.ExprString(x.Type)
if len(tp) == 0 {
// Can this happen?
continue // maybe report this someday
}
// This is only safe if ExprString never returns anything with a $
// The only place a $ can occur seems to be in a struct tag, which
// can be an arbitrary string literal, and ExprString does not presently
// print struct tags. So for this to happen the type of a formal parameter
// has to be a explict struct, e.g. foo(x struct{a int "$"}) and ExprString
// would have to show the struct tag. Even testing for this case seems
// a waste of effort, but let's not ignore such pathologies
if strings.Contains(tp, "$") {
continue
}
tp = strings.Replace(tp, " ", "$", -1)
if len(x.Names) == 0 {
result = append(result, "_")
result = append(result, tp)
} else {
for _, y := range x.Names {
result = append(result, y.Name)
result = append(result, tp)
}
}
}
sigs := strings.Join(result, " ")
if s := newsym(pkg, name, kind, sigs); s != nil {
ans = append(ans, *s)
}
case *ast.GenDecl:
switch decl.Tok {
case token.CONST, token.VAR:
tp := "V"
if decl.Tok == token.CONST {
tp = "C"
}
for _, sp := range decl.Specs {
for _, x := range sp.(*ast.ValueSpec).Names {
if s := newsym(pkg, x.Name, tp, ""); s != nil {
ans = append(ans, *s)
}
}
}
case token.TYPE:
for _, sp := range decl.Specs {
if s := newsym(pkg, sp.(*ast.TypeSpec).Name.Name, "T", ""); s != nil {
ans = append(ans, *s)
}
}
}
}
}
return ans
}
func newsym(pkg, name, kind, sig string) *symbol {
if len(name) == 0 || !ast.IsExported(name) {
return nil
}
sym := symbol{pkg: pkg, name: name, kind: kind, sig: sig}
return &sym
}
// return the package name and the value for the symbols.
// if there are multiple packages, choose one arbitrarily
// the returned slice is sorted lexicographically
func processSyms(syms []symbol) (string, []string) {
if len(syms) == 0 {
return "", nil
}
slices.SortFunc(syms, func(l, r symbol) int {
return strings.Compare(l.name, r.name)
})
pkg := syms[0].pkg
var names []string
for _, s := range syms {
var nx string
if s.pkg == pkg {
if s.sig != "" {
nx = fmt.Sprintf("%s %s %s", s.name, s.kind, s.sig)
} else {
nx = fmt.Sprintf("%s %s", s.name, s.kind)
}
names = append(names, nx)
} else {
continue // PJW: do we want to keep track of these?
}
}
return pkg, names
}
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