github.com/gernest/nezuko@v0.1.2/internal/build/build.go

package build

import (
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	pathpkg "path"
	"path/filepath"
	"runtime"
	"strings"
)

// An ImportMode controls the behavior of the Import method.
type ImportMode uint

const (
	// If FindOnly is set, Import stops after locating the directory
	// that should contain the sources for a package. It does not
	// read any files in the directory.
	FindOnly ImportMode = 1 << iota

	// If AllowBinary is set, Import can be satisfied by a compiled
	// package object without corresponding sources.
	//
	// Deprecated:
	// The supported way to create a compiled-only package is to
	// write source code containing a //go:binary-only-package comment at
	// the top of the file. Such a package will be recognized
	// regardless of this flag setting (because it has source code)
	// and will have BinaryOnly set to true in the returned Package.
	AllowBinary

	// If ImportComment is set, parse import comments on package statements.
	// Import returns an error if it finds a comment it cannot understand
	// or finds conflicting comments in multiple source files.
	// See golang.org/s/go14customimport for more information.
	ImportComment

	// By default, Import searches vendor directories
	// that apply in the given source directory before searching
	// the GOROOT and GOPATH roots.
	// If an Import finds and returns a package using a vendor
	// directory, the resulting ImportPath is the complete path
	// to the package, including the path elements leading up
	// to and including "vendor".
	// For example, if Import("y", "x/subdir", 0) finds
	// "x/vendor/y", the returned package's ImportPath is "x/vendor/y",
	// not plain "y".
	// See golang.org/s/go15vendor for more information.
	//
	// Setting IgnoreVendor ignores vendor directories.
	//
	// In contrast to the package's ImportPath,
	// the returned package's Imports, TestImports, and XTestImports
	// are always the exact import paths from the source files:
	// Import makes no attempt to resolve or check those paths.
	IgnoreVendor
)

var Default Context = defaultContext()

type Context struct {
	ZIGPATH string // Go path

	JoinPath func(elem ...string) string

	// SplitPathList splits the path list into a slice of individual paths.
	// If SplitPathList is nil, Import uses filepath.SplitList.
	SplitPathList func(list string) []string

	// IsAbsPath reports whether path is an absolute path.
	// If IsAbsPath is nil, Import uses filepath.IsAbs.
	IsAbsPath func(path string) bool

	// IsDir reports whether the path names a directory.
	// If IsDir is nil, Import calls os.Stat and uses the result's IsDir method.
	IsDir func(path string) bool

	// HasSubdir reports whether dir is lexically a subdirectory of
	// root, perhaps multiple levels below. It does not try to check
	// whether dir exists.
	// If so, HasSubdir sets rel to a slash-separated path that
	// can be joined to root to produce a path equivalent to dir.
	// If HasSubdir is nil, Import uses an implementation built on
	// filepath.EvalSymlinks.
	HasSubdir func(root, dir string) (rel string, ok bool)

	// ReadDir returns a slice of os.FileInfo, sorted by Name,
	// describing the content of the named directory.
	// If ReadDir is nil, Import uses ioutil.ReadDir.
	ReadDir func(dir string) ([]os.FileInfo, error)

	// OpenFile opens a file (not a directory) for reading.
	// If OpenFile is nil, Import uses os.Open.
	OpenFile func(path string) (io.ReadCloser, error)
}

func envOr(name, def string) string {
	s := os.Getenv(name)
	if s == "" {
		return def
	}
	return s
}

func defaultGOPATH() string {
	env := "HOME"
	if runtime.GOOS == "windows" {
		env = "USERPROFILE"
	} else if runtime.GOOS == "plan9" {
		env = "home"
	}
	if home := os.Getenv(env); home != "" {
		def := filepath.Join(home, "zig")
		return def
	}
	return ""
}

func defaultContext() Context {
	var c Context
	c.ZIGPATH = envOr("ZIGPATH", defaultGOPATH())
	return c
}

func (ctxt *Context) ImportDir(dir string, mode ImportMode) (*Package, error) {
	return ctxt.Import(".", dir, mode)
}

func (ctxt *Context) isAbsPath(path string) bool {
	if f := ctxt.IsAbsPath; f != nil {
		return f(path)
	}
	return filepath.IsAbs(path)
}

// joinPath calls ctxt.JoinPath (if not nil) or else filepath.Join.
func (ctxt *Context) joinPath(elem ...string) string {
	if f := ctxt.JoinPath; f != nil {
		return f(elem...)
	}
	return filepath.Join(elem...)
}

// splitPathList calls ctxt.SplitPathList (if not nil) or else filepath.SplitList.
func (ctxt *Context) splitPathList(s string) []string {
	if f := ctxt.SplitPathList; f != nil {
		return f(s)
	}
	return filepath.SplitList(s)
}

func (ctxt *Context) gopath() []string {
	var all []string
	for _, p := range ctxt.splitPathList(ctxt.ZIGPATH) {
		if p == "" {
			// Empty paths are uninteresting.
			// If the path is the GOROOT, ignore it.
			// People sometimes set GOPATH=$GOROOT.
			// Do not get confused by this common mistake.
			continue
		}
		if strings.HasPrefix(p, "~") {
			// Path segments starting with ~ on Unix are almost always
			// users who have incorrectly quoted ~ while setting GOPATH,
			// preventing it from expanding to $HOME.
			// The situation is made more confusing by the fact that
			// bash allows quoted ~ in $PATH (most shells do not).
			// Do not get confused by this, and do not try to use the path.
			// It does not exist, and printing errors about it confuses
			// those users even more, because they think "sure ~ exists!".
			// The go command diagnoses this situation and prints a
			// useful error.
			// On Windows, ~ is used in short names, such as c:\progra~1
			// for c:\program files.
			continue
		}
		all = append(all, p)
	}
	return all
}

// hasSubdir calls ctxt.HasSubdir (if not nil) or else uses
// the local file system to answer the question.
func (ctxt *Context) hasSubdir(root, dir string) (rel string, ok bool) {
	if f := ctxt.HasSubdir; f != nil {
		return f(root, dir)
	}

	// Try using paths we received.
	if rel, ok = hasSubdir(root, dir); ok {
		return
	}

	// Try expanding symlinks and comparing
	// expanded against unexpanded and
	// expanded against expanded.
	rootSym, _ := filepath.EvalSymlinks(root)
	dirSym, _ := filepath.EvalSymlinks(dir)

	if rel, ok = hasSubdir(rootSym, dir); ok {
		return
	}
	if rel, ok = hasSubdir(root, dirSym); ok {
		return
	}
	return hasSubdir(rootSym, dirSym)
}

// hasSubdir reports if dir is within root by performing lexical analysis only.
func hasSubdir(root, dir string) (rel string, ok bool) {
	const sep = string(filepath.Separator)
	root = filepath.Clean(root)
	if !strings.HasSuffix(root, sep) {
		root += sep
	}
	dir = filepath.Clean(dir)
	if !strings.HasPrefix(dir, root) {
		return "", false
	}
	return filepath.ToSlash(dir[len(root):]), true
}

// isDir calls ctxt.IsDir (if not nil) or else uses os.Stat.
func (ctxt *Context) isDir(path string) bool {
	if f := ctxt.IsDir; f != nil {
		return f(path)
	}
	fi, err := os.Stat(path)
	return err == nil && fi.IsDir()
}

var errNoModules = errors.New("not using modules")

func (ctxt *Context) importGo(p *Package, path, srcDir string, mode ImportMode, gopath []string) error {
	const debugImportGo = false

	// To invoke the go command, we must know the source directory,
	// we must not being doing special things like AllowBinary or IgnoreVendor,
	// and all the file system callbacks must be nil (we're meant to use the local file system).
	if srcDir == "" ||
		ctxt.JoinPath != nil || ctxt.SplitPathList != nil || ctxt.IsAbsPath != nil || ctxt.IsDir != nil || ctxt.HasSubdir != nil || ctxt.ReadDir != nil || ctxt.OpenFile != nil {
		return errNoModules
	}

	// Look to see if there is a go.mod.
	abs, err := filepath.Abs(srcDir)
	if err != nil {
		return errNoModules
	}
	for {
		info, err := os.Stat(filepath.Join(abs, "go.mod"))
		if err == nil && !info.IsDir() {
			break
		}
		d := filepath.Dir(abs)
		if len(d) >= len(abs) {
			return errNoModules // reached top of file system, no go.mod
		}
		abs = d
	}

	return nil
}

// readDir calls ctxt.ReadDir (if not nil) or else ioutil.ReadDir.
func (ctxt *Context) readDir(path string) ([]os.FileInfo, error) {
	if f := ctxt.ReadDir; f != nil {
		return f(path)
	}
	return ioutil.ReadDir(path)
}

// hasGoFiles reports whether dir contains any files with names ending in .go.
// For a vendor check we must exclude directories that contain no .go files.
// Otherwise it is not possible to vendor just a/b/c and still import the
// non-vendored a/b. See golang.org/issue/13832.
func hasGoFiles(ctxt *Context, dir string) bool {
	ents, _ := ctxt.readDir(dir)
	for _, ent := range ents {
		if !ent.IsDir() && strings.HasSuffix(ent.Name(), ".zig") {
			return true
		}
	}
	return false
}

// openFile calls ctxt.OpenFile (if not nil) or else os.Open.
func (ctxt *Context) openFile(path string) (io.ReadCloser, error) {
	if fn := ctxt.OpenFile; fn != nil {
		return fn(path)
	}

	f, err := os.Open(path)
	if err != nil {
		return nil, err // nil interface
	}
	return f, nil
}

func (ctxt *Context) IsFile(path string) bool {
	return ctxt.isFile(path)
}

// isFile determines whether path is a file by trying to open it.
// It reuses openFile instead of adding another function to the
// list in Context.
func (ctxt *Context) isFile(path string) bool {
	f, err := ctxt.openFile(path)
	if err != nil {
		return false
	}
	f.Close()
	return true
}

// Import imports package
func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Package, error) {
	p := &Package{
		ImportPath: path,
	}
	if path == "" {
		return p, fmt.Errorf("import %q: invalid import path", path)
	}

	var pkgerr error
	binaryOnly := false
	if IsLocalImport(path) {
		if srcDir == "" {
			return p, fmt.Errorf("import %q: import relative to unknown directory", path)
		}
		if !ctxt.isAbsPath(path) {
			p.Dir = ctxt.joinPath(srcDir, path)
		}
		// p.Dir directory may or may not exist. Gather partial information first, check if it exists later.
		// Determine canonical import path, if any.
		// Exclude results where the import path would include /testdata/.
		inTestdata := func(sub string) bool {
			return strings.Contains(sub, "/testdata/") || strings.HasSuffix(sub, "/testdata") || strings.HasPrefix(sub, "testdata/") || sub == "testdata"
		}
		all := ctxt.gopath()
		for i, root := range all {
			rootsrc := ctxt.joinPath(root, "src")
			if sub, ok := ctxt.hasSubdir(rootsrc, p.Dir); ok && !inTestdata(sub) {
				// We found a potential import path for dir,
				// but check that using it wouldn't find something
				// else first.
				for _, earlyRoot := range all[:i] {
					if dir := ctxt.joinPath(earlyRoot, "src", sub); ctxt.isDir(dir) {
						p.ConflictDir = dir
						goto Found
					}
				}

				// sub would not name some other directory instead of this one.
				// Record it.
				p.ImportPath = sub
				p.Root = root
				goto Found
			}
		}
		// It's okay that we didn't find a root containing dir.
		// Keep going with the information we have.
	} else {
		if strings.HasPrefix(path, "/") {
			return p, fmt.Errorf("import %q: cannot import absolute path", path)
		}

		gopath := ctxt.gopath() // needed by both importGo and below; avoid computing twice
		if err := ctxt.importGo(p, path, srcDir, mode, gopath); err == nil {
			goto Found
		} else if err != errNoModules {
			return p, err
		}

		// tried records the location of unsuccessful package lookups
		var tried struct {
			vendor []string
			gopath []string
		}

		// Vendor directories get first chance to satisfy import.
		if mode&IgnoreVendor == 0 && srcDir != "" {
			searchVendor := func(root string, isGoroot bool) bool {
				sub, ok := ctxt.hasSubdir(root, srcDir)
				if !ok || !strings.HasPrefix(sub, "src/") || strings.Contains(sub, "/testdata/") {
					return false
				}
				for {
					vendor := ctxt.joinPath(root, sub, "vendor")
					if ctxt.isDir(vendor) {
						dir := ctxt.joinPath(vendor, path)
						if ctxt.isDir(dir) && hasGoFiles(ctxt, dir) {
							p.Dir = dir
							p.ImportPath = strings.TrimPrefix(pathpkg.Join(sub, "vendor", path), "src/")
							p.Root = root
							return true
						}
						tried.vendor = append(tried.vendor, dir)
					}
					i := strings.LastIndex(sub, "/")
					if i < 0 {
						break
					}
					sub = sub[:i]
				}
				return false
			}
			for _, root := range gopath {
				if searchVendor(root, false) {
					goto Found
				}
			}
		}

		for _, root := range gopath {
			dir := ctxt.joinPath(root, "src", path)
			isDir := ctxt.isDir(dir)
			if isDir {
				p.Dir = dir
				p.Root = root
				goto Found
			}
			tried.gopath = append(tried.gopath, dir)
		}

		// package was not found
		var paths []string
		format := "\t%s (vendor tree)"
		for _, dir := range tried.vendor {
			paths = append(paths, fmt.Sprintf(format, dir))
			format = "\t%s"
		}

		paths = append(paths, "\t($GOROOT not set)")
		format = "\t%s (from $GOPATH)"
		for _, dir := range tried.gopath {
			paths = append(paths, fmt.Sprintf(format, dir))
			format = "\t%s"
		}
		if len(tried.gopath) == 0 {
			paths = append(paths, "\t($GOPATH not set. For more details see: 'go help gopath')")
		}
		return p, fmt.Errorf("cannot find package %q in any of:\n%s", path, strings.Join(paths, "\n"))
	}

Found:
	if p.Root != "" {
		p.SrcRoot = ctxt.joinPath(p.Root, "src")
		p.PkgRoot = ctxt.joinPath(p.Root, "pkg")
	}

	// If it's a local import path, by the time we get here, we still haven't checked
	// that p.Dir directory exists. This is the right time to do that check.
	// We can't do it earlier, because we want to gather partial information for the
	// non-nil *Package returned when an error occurs.
	// We need to do this before we return early on FindOnly flag.
	if IsLocalImport(path) && !ctxt.isDir(p.Dir) {
		// package was not found
		return p, fmt.Errorf("cannot find package %q in:\n\t%s", path, p.Dir)
	}

	if mode&FindOnly != 0 {
		return p, pkgerr
	}
	if binaryOnly && (mode&AllowBinary) != 0 {
		return p, pkgerr
	}

	dirs, err := ctxt.readDir(p.Dir)
	if err != nil {
		return p, err
	}

	// TODO(gernest) load package from z.mod
	for _, d := range dirs {
		if d.IsDir() {
			continue
		}
	}
	return p, pkgerr
}

// A Package describes the Go package found in a directory.
type Package struct {
	Dir           string // directory containing package sources
	Name          string // package name
	ImportComment string // path in import comment on package statement
	Doc           string // documentation synopsis
	ImportPath    string // import path of package ("" if unknown)
	Root          string // root of Go tree where this package lives
	SrcRoot       string // package source root directory ("" if unknown)
	PkgRoot       string // package install root directory ("" if unknown)
	ConflictDir   string // this directory shadows Dir in $GOPATH

	// Source files
	GoFiles []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)

	// Dependency information
	Imports []string // import paths from GoFiles, CgoFiles
}

// IsLocalImport reports whether the import path is
// a local import path, like ".", "..", "./foo", or "../foo".
func IsLocalImport(path string) bool {
	return path == "." || path == ".." ||
		strings.HasPrefix(path, "./") || strings.HasPrefix(path, "../")
}