loader

type Config struct {
	// Fset is the file set for the parser to use when loading the
	// program.  If nil, it may be lazily initialized by any
	// method of Config.
	Fset *token.FileSet

	// ParserMode specifies the mode to be used by the parser when
	// loading source packages.
	ParserMode parser.Mode

	// TypeChecker contains options relating to the type checker.
	//
	// The supplied IgnoreFuncBodies is not used; the effective
	// value comes from the TypeCheckFuncBodies func below.
	//
	// TypeChecker.Packages is lazily initialized during Load.
	TypeChecker types.Config

	// TypeCheckFuncBodies is a predicate over package import
	// paths.  A package for which the predicate is false will
	// have its package-level declarations type checked, but not
	// its function bodies; this can be used to quickly load
	// dependencies from source.  If nil, all func bodies are type
	// checked.
	TypeCheckFuncBodies func(string) bool

	// ImportFromBinary determines whether to satisfy dependencies by
	// loading gc export data instead of Go source code.
	//
	// If false, the entire program---the initial packages and their
	// transitive closure of dependencies---will be loaded from
	// source, parsed, and type-checked.  This is required for
	// whole-program analyses such as pointer analysis.
	//
	// If true, the go/gcimporter mechanism is used instead to read
	// the binary export-data files written by the gc toolchain.
	// They supply only the types of package-level declarations and
	// values of constants, but no code, this option will not yield
	// a whole program.  It is intended for analyses that perform
	// modular analysis of a single package, e.g. traditional
	// compilation.
	//
	// No check is made that the export data files are up-to-date.
	//
	// The initial packages (CreatePkgs and ImportPkgs) are always
	// loaded from Go source, regardless of this flag's setting.
	//
	// NB: there is a bug when loading multiple initial packages with
	// this flag enabled: https://github.com/golang/go/issues/9955.
	ImportFromBinary bool

	// If Build is non-nil, it is used to locate source packages.
	// Otherwise &build.Default is used.
	//
	// By default, cgo is invoked to preprocess Go files that
	// import the fake package "C".  This behaviour can be
	// disabled by setting CGO_ENABLED=0 in the environment prior
	// to startup, or by setting Build.CgoEnabled=false.
	Build *build.Context

	// If DisplayPath is non-nil, it is used to transform each
	// file name obtained from Build.Import().  This can be used
	// to prevent a virtualized build.Config's file names from
	// leaking into the user interface.
	DisplayPath func(path string) string

	// If AllowErrors is true, Load will return a Program even
	// if some of the its packages contained I/O, parser or type
	// errors; such errors are accessible via PackageInfo.Errors.  If
	// false, Load will fail if any package had an error.
	AllowErrors bool

	// CreatePkgs specifies a list of non-importable initial
	// packages to create.  The resulting packages will appear in
	// the corresponding elements of the Program.Created slice.
	CreatePkgs []PkgSpec

	// ImportPkgs specifies a set of initial packages to load from
	// source.  The map keys are package import paths, used to
	// locate the package relative to $GOROOT.
	//
	// The map value indicates whether to load tests.  If true, Load
	// will add and type-check two lists of files to the package:
	// non-test files followed by in-package *_test.go files.  In
	// addition, it will append the external test package (if any)
	// to Program.Created.
	ImportPkgs map[string]bool

	// FindPackage is called during Load to create the build.Package
	// for a given import path.  If nil, a default implementation
	// based on ctxt.Import is used.  A client may use this hook to
	// adapt to a proprietary build system that does not follow the
	// "go build" layout conventions, for example.
	//
	// It must be safe to call concurrently from multiple goroutines.
	FindPackage func(ctxt *build.Context, importPath string) (*build.Package, error)

	// PackageCreated is a hook called when a types.Package
	// is created but before it has been populated.
	//
	// The package's import Path() and Scope() are defined,
	// but not its Name() since no package declaration has
	// been seen yet.
	//
	// Clients may use this to insert synthetic items into
	// the package scope, for example.
	//
	// It must be safe to call concurrently from multiple goroutines.
	PackageCreated func(*types.Package)
}

type PackageInfo struct {
	Pkg                   *types.Package
	Importable            bool        // true if 'import "Pkg.Path()"' would resolve to this
	TransitivelyErrorFree bool        // true if Pkg and all its dependencies are free of errors
	Files                 []*ast.File // syntax trees for the package's files
	Errors                []error     // non-nil if the package had errors
	types.Info                        // type-checker deductions.
	// contains filtered or unexported fields
}

type PkgSpec struct {
	Path      string      // import path ("" => use package declaration)
	Files     []*ast.File // ASTs of already-parsed files
	Filenames []string    // names of files to be parsed
}

type Program struct {
	Fset *token.FileSet // the file set for this program

	// Created[i] contains the initial package whose ASTs or
	// filenames were supplied by Config.CreatePkgs[i], followed by
	// the external test package, if any, of each package in
	// Config.ImportPkgs ordered by ImportPath.
	Created []*PackageInfo

	// Imported contains the initially imported packages,
	// as specified by Config.ImportPkgs.
	Imported map[string]*PackageInfo

	// ImportMap is the canonical mapping of import paths to
	// packages used by the type-checker (Config.TypeChecker.Packages).
	// It contains all Imported initial packages, but not Created
	// ones, and all imported dependencies.
	ImportMap map[string]*types.Package

	// AllPackages contains the PackageInfo of every package
	// encountered by Load: all initial packages and all
	// dependencies, including incomplete ones.
	AllPackages map[*types.Package]*PackageInfo
}