diff options
Diffstat (limited to 'tools/go_marshal/gomarshal/util.go')
| -rw-r--r-- | tools/go_marshal/gomarshal/util.go | 503 |
1 files changed, 0 insertions, 503 deletions
diff --git a/tools/go_marshal/gomarshal/util.go b/tools/go_marshal/gomarshal/util.go deleted file mode 100644 index 6a42691cd..000000000 --- a/tools/go_marshal/gomarshal/util.go +++ /dev/null @@ -1,503 +0,0 @@ -// Copyright 2019 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -package gomarshal - -import ( - "bytes" - "flag" - "fmt" - "go/ast" - "go/token" - "io" - "os" - "path" - "reflect" - "sort" - "strings" -) - -var debug = flag.Bool("debug", false, "enables debugging output") - -// receiverName returns an appropriate receiver name given a type spec. -func receiverName(t *ast.TypeSpec) string { - if len(t.Name.Name) < 1 { - // Zero length type name? - panic("unreachable") - } - return strings.ToLower(t.Name.Name[:1]) -} - -// kindString returns a user-friendly representation of an AST expr type. -func kindString(e ast.Expr) string { - switch e.(type) { - case *ast.Ident: - return "scalar" - case *ast.ArrayType: - return "array" - case *ast.StructType: - return "struct" - case *ast.StarExpr: - return "pointer" - case *ast.FuncType: - return "function" - case *ast.InterfaceType: - return "interface" - case *ast.MapType: - return "map" - case *ast.ChanType: - return "channel" - default: - return reflect.TypeOf(e).String() - } -} - -func forEachStructField(st *ast.StructType, fn func(f *ast.Field)) { - for _, field := range st.Fields.List { - fn(field) - } -} - -// fieldDispatcher is a collection of callbacks for handling different types of -// fields in a struct declaration. -type fieldDispatcher struct { - primitive func(n, t *ast.Ident) - selector func(n, tX, tSel *ast.Ident) - array func(n *ast.Ident, a *ast.ArrayType, t *ast.Ident) - unhandled func(n *ast.Ident) -} - -// Precondition: All dispatch callbacks that will be invoked must be -// provided. -func (fd fieldDispatcher) dispatch(f *ast.Field) { - // Each field declaration may actually be multiple declarations of the same - // type. For example, consider: - // - // type Point struct { - // x, y, z int - // } - // - // We invoke the call-backs once per such instance. - - // Handle embedded fields. Embedded fields have no names, but can be - // referenced by the type name. - if len(f.Names) < 1 { - switch v := f.Type.(type) { - case *ast.Ident: - fd.primitive(v, v) - case *ast.SelectorExpr: - fd.selector(v.Sel, v.X.(*ast.Ident), v.Sel) - default: - // Note: Arrays can't be embedded, which is handled here. - panic(fmt.Sprintf("Attempted to dispatch on embedded field of unsupported kind: %#v", f.Type)) - } - return - } - - // Non-embedded field. - for _, name := range f.Names { - switch v := f.Type.(type) { - case *ast.Ident: - fd.primitive(name, v) - case *ast.SelectorExpr: - fd.selector(name, v.X.(*ast.Ident), v.Sel) - case *ast.ArrayType: - switch t := v.Elt.(type) { - case *ast.Ident: - fd.array(name, v, t) - default: - // Should be handled with a better error message during validate. - panic(fmt.Sprintf("Array element type is of unsupported kind. Expected *ast.Ident, got %v", t)) - } - default: - fd.unhandled(name) - } - } -} - -// debugEnabled indicates whether debugging is enabled for gomarshal. -func debugEnabled() bool { - return *debug -} - -// abort aborts the go_marshal tool with the given error message. -func abort(msg string) { - if !strings.HasSuffix(msg, "\n") { - msg += "\n" - } - fmt.Print(msg) - os.Exit(1) -} - -// abortAt aborts the go_marshal tool with the given error message, with -// a reference position to the input source. -func abortAt(p token.Position, msg string) { - abort(fmt.Sprintf("%v:\n %s\n", p, msg)) -} - -// debugf conditionally prints a debug message. -func debugf(f string, a ...interface{}) { - if debugEnabled() { - fmt.Printf(f, a...) - } -} - -// debugfAt conditionally prints a debug message with a reference to a position -// in the input source. -func debugfAt(p token.Position, f string, a ...interface{}) { - if debugEnabled() { - fmt.Printf("%s:\n %s", p, fmt.Sprintf(f, a...)) - } -} - -// emit generates a line of code in the output file. -// -// emit is a wrapper around writing a formatted string to the output -// buffer. emit can be invoked in one of two ways: -// -// (1) emit("some string") -// When emit is called with a single string argument, it is simply copied to -// the output buffer without any further formatting. -// (2) emit(fmtString, args...) -// emit can also be invoked in a similar fashion to *Printf() functions, -// where the first argument is a format string. -// -// Calling emit with a single argument that is not a string will result in a -// panic, as the caller's intent is ambiguous. -func emit(out io.Writer, indent int, a ...interface{}) { - const spacesPerIndentLevel = 4 - - if len(a) < 1 { - panic("emit() called with no arguments") - } - - if indent > 0 { - if _, err := fmt.Fprint(out, strings.Repeat(" ", indent*spacesPerIndentLevel)); err != nil { - // Writing to the emit output should not fail. Typically the output - // is a byte.Buffer; writes to these never fail. - panic(err) - } - } - - first, ok := a[0].(string) - if !ok { - // First argument must be either the string to emit (case 1 from - // function-level comment), or a format string (case 2). - panic(fmt.Sprintf("First argument to emit() is not a string: %+v", a[0])) - } - - if len(a) == 1 { - // Single string argument. Assume no formatting requested. - if _, err := fmt.Fprint(out, first); err != nil { - // Writing to out should not fail. - panic(err) - } - return - - } - - // Formatting requested. - if _, err := fmt.Fprintf(out, first, a[1:]...); err != nil { - // Writing to out should not fail. - panic(err) - } -} - -// sourceBuffer represents fragments of generated go source code. -// -// sourceBuffer provides a convenient way to build up go souce fragments in -// memory. May be safely zero-value initialized. Not thread-safe. -type sourceBuffer struct { - // Current indentation level. - indent int - - // Memory buffer containing contents while they're being generated. - b bytes.Buffer -} - -func (b *sourceBuffer) reset() { - b.indent = 0 - b.b.Reset() -} - -func (b *sourceBuffer) incIndent() { - b.indent++ -} - -func (b *sourceBuffer) decIndent() { - if b.indent <= 0 { - panic("decIndent() without matching incIndent()") - } - b.indent-- -} - -func (b *sourceBuffer) emit(a ...interface{}) { - emit(&b.b, b.indent, a...) -} - -func (b *sourceBuffer) emitNoIndent(a ...interface{}) { - emit(&b.b, 0 /*indent*/, a...) -} - -func (b *sourceBuffer) inIndent(body func()) { - b.incIndent() - body() - b.decIndent() -} - -func (b *sourceBuffer) write(out io.Writer) error { - _, err := fmt.Fprint(out, b.b.String()) - return err -} - -// Write implements io.Writer.Write. -func (b *sourceBuffer) Write(buf []byte) (int, error) { - return (b.b.Write(buf)) -} - -// importStmt represents a single import statement. -type importStmt struct { - // Local name of the imported package. - name string - // Import path. - path string - // Indicates whether the local name is an alias, or simply the final - // component of the path. - aliased bool - // Indicates whether this import was referenced by generated code. - used bool - // AST node and file set representing the import statement, if any. These - // are only non-nil if the import statement originates from an input source - // file. - spec *ast.ImportSpec - fset *token.FileSet -} - -func newImport(p string) *importStmt { - name := path.Base(p) - return &importStmt{ - name: name, - path: p, - aliased: false, - } -} - -func newImportFromSpec(spec *ast.ImportSpec, f *token.FileSet) *importStmt { - p := spec.Path.Value[1 : len(spec.Path.Value)-1] // Strip the " quotes around path. - name := path.Base(p) - if name == "" || name == "/" || name == "." { - panic(fmt.Sprintf("Couldn't process local package name for import at %s, (processed as %s)", - f.Position(spec.Path.Pos()), name)) - } - if spec.Name != nil { - name = spec.Name.Name - } - return &importStmt{ - name: name, - path: p, - aliased: spec.Name != nil, - spec: spec, - fset: f, - } -} - -// String implements fmt.Stringer.String. This generates a string for the import -// statement appropriate for writing directly to generated code. -func (i *importStmt) String() string { - if i.aliased { - return fmt.Sprintf("%s %q", i.name, i.path) - } - return fmt.Sprintf("%q", i.path) -} - -// debugString returns a debug string representing an import statement. This -// representation is not valid golang code and is used for debugging output. -func (i *importStmt) debugString() string { - if i.spec != nil && i.fset != nil { - return fmt.Sprintf("%s: %s", i.fset.Position(i.spec.Path.Pos()), i) - } - return fmt.Sprintf("(go-marshal import): %s", i) -} - -func (i *importStmt) markUsed() { - i.used = true -} - -func (i *importStmt) equivalent(other *importStmt) bool { - return i.name == other.name && i.path == other.path && i.aliased == other.aliased -} - -// importTable represents a collection of importStmts. -// -// An importTable may contain multiple import statements referencing the same -// local name. All import statements aliasing to the same local name are -// technically ambiguous, as if such an import name is used in the generated -// code, it's not clear which import statement it refers to. We ignore any -// potential collisions until actually writing the import table to the generated -// source file. See importTable.write. -// -// Given the following import statements across all the files comprising a -// package marshalled: -// -// "sync" -// "pkg/sync" -// "pkg/sentry/kernel" -// ktime "pkg/sentry/kernel/time" -// -// An importTable representing them would look like this: -// -// importTable { -// is: map[string][]*importStmt { -// "sync": []*importStmt{ -// importStmt{name:"sync", path:"sync", aliased:false} -// importStmt{name:"sync", path:"pkg/sync", aliased:false} -// }, -// "kernel": []*importStmt{importStmt{ -// name: "kernel", -// path: "pkg/sentry/kernel", -// aliased: false -// }}, -// "ktime": []*importStmt{importStmt{ -// name: "ktime", -// path: "pkg/sentry/kernel/time", -// aliased: true, -// }}, -// } -// } -// -// Note that the local name "sync" is assigned to two different import -// statements. This is possible if the import statements are from different -// source files in the same package. -// -// Since go-marshal generates a single output file per package regardless of the -// number of input files, if "sync" is referenced by any generated code, it's -// unclear which import statement "sync" refers to. While it's theoretically -// possible to resolve this by assigning a unique local alias to each instance -// of the sync package, go-marshal currently aborts when it encounters such an -// ambiguity. -// -// TODO(b/151478251): importTable considers the final component of an import -// path to be the package name, but this is only a convention. The actual -// package name is determined by the package statement in the source files for -// the package. -type importTable struct { - // Map of imports and whether they should be copied to the output. - is map[string][]*importStmt -} - -func newImportTable() *importTable { - return &importTable{ - is: make(map[string][]*importStmt), - } -} - -// Merges import statements from other into i. -func (i *importTable) merge(other *importTable) { - for name, ims := range other.is { - i.is[name] = append(i.is[name], ims...) - } -} - -func (i *importTable) addStmt(s *importStmt) *importStmt { - i.is[s.name] = append(i.is[s.name], s) - return s -} - -func (i *importTable) add(s string) *importStmt { - n := newImport(s) - return i.addStmt(n) -} - -func (i *importTable) addFromSpec(spec *ast.ImportSpec, f *token.FileSet) *importStmt { - return i.addStmt(newImportFromSpec(spec, f)) -} - -// Marks the import named n as used. If no such import is in the table, returns -// false. -func (i *importTable) markUsed(n string) bool { - if ns, ok := i.is[n]; ok { - for _, n := range ns { - n.markUsed() - } - return true - } - return false -} - -func (i *importTable) clear() { - for _, is := range i.is { - for _, i := range is { - i.used = false - } - } -} - -func (i *importTable) write(out io.Writer) error { - if len(i.is) == 0 { - // Nothing to import, we're done. - return nil - } - - imports := make([]string, 0, len(i.is)) - for name, is := range i.is { - var lastUsed *importStmt - var ambiguous bool - - for _, i := range is { - if i.used { - if lastUsed != nil { - if !i.equivalent(lastUsed) { - ambiguous = true - } - } - lastUsed = i - } - } - - if ambiguous { - // We have two or more import statements across the different source - // files that share a local name, and at least one of these imports - // are used by the generated code. This ambiguity can't be resolved - // by go-marshal and requires the user intervention. Dump a list of - // the colliding import statements and let the user modify the input - // files as appropriate. - var b strings.Builder - fmt.Fprintf(&b, "The imported name %q is used by one of the types marked for marshalling, and which import statement the code refers to is ambiguous. Perhaps give the imports unique local names?\n\n", name) - fmt.Fprintf(&b, "The following %d import statements are ambiguous for the local name %q:\n", len(is), name) - // Note: len(is) is guaranteed to be 1 or greater or ambiguous can't - // be true. Therefore the slicing below is safe. - for _, i := range is[:len(is)-1] { - fmt.Fprintf(&b, " %v\n", i.debugString()) - } - fmt.Fprintf(&b, " %v", is[len(is)-1].debugString()) - panic(b.String()) - } - - if lastUsed != nil { - imports = append(imports, lastUsed.String()) - } - } - sort.Strings(imports) - - var b sourceBuffer - b.emit("import (\n") - b.incIndent() - for _, i := range imports { - b.emit("%s\n", i) - } - b.decIndent() - b.emit(")\n\n") - - return b.write(out) -} |