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-rw-r--r--vendor/google.golang.org/appengine/cmd/aefix/typecheck.go673
1 files changed, 673 insertions, 0 deletions
diff --git a/vendor/google.golang.org/appengine/cmd/aefix/typecheck.go b/vendor/google.golang.org/appengine/cmd/aefix/typecheck.go
new file mode 100644
index 000000000..d54d37547
--- /dev/null
+++ b/vendor/google.golang.org/appengine/cmd/aefix/typecheck.go
@@ -0,0 +1,673 @@
+// Copyright 2011 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 main
+
+import (
+ "fmt"
+ "go/ast"
+ "go/token"
+ "os"
+ "reflect"
+ "strings"
+)
+
+// Partial type checker.
+//
+// The fact that it is partial is very important: the input is
+// an AST and a description of some type information to
+// assume about one or more packages, but not all the
+// packages that the program imports. The checker is
+// expected to do as much as it can with what it has been
+// given. There is not enough information supplied to do
+// a full type check, but the type checker is expected to
+// apply information that can be derived from variable
+// declarations, function and method returns, and type switches
+// as far as it can, so that the caller can still tell the types
+// of expression relevant to a particular fix.
+//
+// TODO(rsc,gri): Replace with go/typechecker.
+// Doing that could be an interesting test case for go/typechecker:
+// the constraints about working with partial information will
+// likely exercise it in interesting ways. The ideal interface would
+// be to pass typecheck a map from importpath to package API text
+// (Go source code), but for now we use data structures (TypeConfig, Type).
+//
+// The strings mostly use gofmt form.
+//
+// A Field or FieldList has as its type a comma-separated list
+// of the types of the fields. For example, the field list
+// x, y, z int
+// has type "int, int, int".
+
+// The prefix "type " is the type of a type.
+// For example, given
+// var x int
+// type T int
+// x's type is "int" but T's type is "type int".
+// mkType inserts the "type " prefix.
+// getType removes it.
+// isType tests for it.
+
+func mkType(t string) string {
+ return "type " + t
+}
+
+func getType(t string) string {
+ if !isType(t) {
+ return ""
+ }
+ return t[len("type "):]
+}
+
+func isType(t string) bool {
+ return strings.HasPrefix(t, "type ")
+}
+
+// TypeConfig describes the universe of relevant types.
+// For ease of creation, the types are all referred to by string
+// name (e.g., "reflect.Value"). TypeByName is the only place
+// where the strings are resolved.
+
+type TypeConfig struct {
+ Type map[string]*Type
+ Var map[string]string
+ Func map[string]string
+}
+
+// typeof returns the type of the given name, which may be of
+// the form "x" or "p.X".
+func (cfg *TypeConfig) typeof(name string) string {
+ if cfg.Var != nil {
+ if t := cfg.Var[name]; t != "" {
+ return t
+ }
+ }
+ if cfg.Func != nil {
+ if t := cfg.Func[name]; t != "" {
+ return "func()" + t
+ }
+ }
+ return ""
+}
+
+// Type describes the Fields and Methods of a type.
+// If the field or method cannot be found there, it is next
+// looked for in the Embed list.
+type Type struct {
+ Field map[string]string // map field name to type
+ Method map[string]string // map method name to comma-separated return types (should start with "func ")
+ Embed []string // list of types this type embeds (for extra methods)
+ Def string // definition of named type
+}
+
+// dot returns the type of "typ.name", making its decision
+// using the type information in cfg.
+func (typ *Type) dot(cfg *TypeConfig, name string) string {
+ if typ.Field != nil {
+ if t := typ.Field[name]; t != "" {
+ return t
+ }
+ }
+ if typ.Method != nil {
+ if t := typ.Method[name]; t != "" {
+ return t
+ }
+ }
+
+ for _, e := range typ.Embed {
+ etyp := cfg.Type[e]
+ if etyp != nil {
+ if t := etyp.dot(cfg, name); t != "" {
+ return t
+ }
+ }
+ }
+
+ return ""
+}
+
+// typecheck type checks the AST f assuming the information in cfg.
+// It returns two maps with type information:
+// typeof maps AST nodes to type information in gofmt string form.
+// assign maps type strings to lists of expressions that were assigned
+// to values of another type that were assigned to that type.
+func typecheck(cfg *TypeConfig, f *ast.File) (typeof map[interface{}]string, assign map[string][]interface{}) {
+ typeof = make(map[interface{}]string)
+ assign = make(map[string][]interface{})
+ cfg1 := &TypeConfig{}
+ *cfg1 = *cfg // make copy so we can add locally
+ copied := false
+
+ // gather function declarations
+ for _, decl := range f.Decls {
+ fn, ok := decl.(*ast.FuncDecl)
+ if !ok {
+ continue
+ }
+ typecheck1(cfg, fn.Type, typeof, assign)
+ t := typeof[fn.Type]
+ if fn.Recv != nil {
+ // The receiver must be a type.
+ rcvr := typeof[fn.Recv]
+ if !isType(rcvr) {
+ if len(fn.Recv.List) != 1 {
+ continue
+ }
+ rcvr = mkType(gofmt(fn.Recv.List[0].Type))
+ typeof[fn.Recv.List[0].Type] = rcvr
+ }
+ rcvr = getType(rcvr)
+ if rcvr != "" && rcvr[0] == '*' {
+ rcvr = rcvr[1:]
+ }
+ typeof[rcvr+"."+fn.Name.Name] = t
+ } else {
+ if isType(t) {
+ t = getType(t)
+ } else {
+ t = gofmt(fn.Type)
+ }
+ typeof[fn.Name] = t
+
+ // Record typeof[fn.Name.Obj] for future references to fn.Name.
+ typeof[fn.Name.Obj] = t
+ }
+ }
+
+ // gather struct declarations
+ for _, decl := range f.Decls {
+ d, ok := decl.(*ast.GenDecl)
+ if ok {
+ for _, s := range d.Specs {
+ switch s := s.(type) {
+ case *ast.TypeSpec:
+ if cfg1.Type[s.Name.Name] != nil {
+ break
+ }
+ if !copied {
+ copied = true
+ // Copy map lazily: it's time.
+ cfg1.Type = make(map[string]*Type)
+ for k, v := range cfg.Type {
+ cfg1.Type[k] = v
+ }
+ }
+ t := &Type{Field: map[string]string{}}
+ cfg1.Type[s.Name.Name] = t
+ switch st := s.Type.(type) {
+ case *ast.StructType:
+ for _, f := range st.Fields.List {
+ for _, n := range f.Names {
+ t.Field[n.Name] = gofmt(f.Type)
+ }
+ }
+ case *ast.ArrayType, *ast.StarExpr, *ast.MapType:
+ t.Def = gofmt(st)
+ }
+ }
+ }
+ }
+ }
+
+ typecheck1(cfg1, f, typeof, assign)
+ return typeof, assign
+}
+
+func makeExprList(a []*ast.Ident) []ast.Expr {
+ var b []ast.Expr
+ for _, x := range a {
+ b = append(b, x)
+ }
+ return b
+}
+
+// Typecheck1 is the recursive form of typecheck.
+// It is like typecheck but adds to the information in typeof
+// instead of allocating a new map.
+func typecheck1(cfg *TypeConfig, f interface{}, typeof map[interface{}]string, assign map[string][]interface{}) {
+ // set sets the type of n to typ.
+ // If isDecl is true, n is being declared.
+ set := func(n ast.Expr, typ string, isDecl bool) {
+ if typeof[n] != "" || typ == "" {
+ if typeof[n] != typ {
+ assign[typ] = append(assign[typ], n)
+ }
+ return
+ }
+ typeof[n] = typ
+
+ // If we obtained typ from the declaration of x
+ // propagate the type to all the uses.
+ // The !isDecl case is a cheat here, but it makes
+ // up in some cases for not paying attention to
+ // struct fields. The real type checker will be
+ // more accurate so we won't need the cheat.
+ if id, ok := n.(*ast.Ident); ok && id.Obj != nil && (isDecl || typeof[id.Obj] == "") {
+ typeof[id.Obj] = typ
+ }
+ }
+
+ // Type-check an assignment lhs = rhs.
+ // If isDecl is true, this is := so we can update
+ // the types of the objects that lhs refers to.
+ typecheckAssign := func(lhs, rhs []ast.Expr, isDecl bool) {
+ if len(lhs) > 1 && len(rhs) == 1 {
+ if _, ok := rhs[0].(*ast.CallExpr); ok {
+ t := split(typeof[rhs[0]])
+ // Lists should have same length but may not; pair what can be paired.
+ for i := 0; i < len(lhs) && i < len(t); i++ {
+ set(lhs[i], t[i], isDecl)
+ }
+ return
+ }
+ }
+ if len(lhs) == 1 && len(rhs) == 2 {
+ // x = y, ok
+ rhs = rhs[:1]
+ } else if len(lhs) == 2 && len(rhs) == 1 {
+ // x, ok = y
+ lhs = lhs[:1]
+ }
+
+ // Match as much as we can.
+ for i := 0; i < len(lhs) && i < len(rhs); i++ {
+ x, y := lhs[i], rhs[i]
+ if typeof[y] != "" {
+ set(x, typeof[y], isDecl)
+ } else {
+ set(y, typeof[x], false)
+ }
+ }
+ }
+
+ expand := func(s string) string {
+ typ := cfg.Type[s]
+ if typ != nil && typ.Def != "" {
+ return typ.Def
+ }
+ return s
+ }
+
+ // The main type check is a recursive algorithm implemented
+ // by walkBeforeAfter(n, before, after).
+ // Most of it is bottom-up, but in a few places we need
+ // to know the type of the function we are checking.
+ // The before function records that information on
+ // the curfn stack.
+ var curfn []*ast.FuncType
+
+ before := func(n interface{}) {
+ // push function type on stack
+ switch n := n.(type) {
+ case *ast.FuncDecl:
+ curfn = append(curfn, n.Type)
+ case *ast.FuncLit:
+ curfn = append(curfn, n.Type)
+ }
+ }
+
+ // After is the real type checker.
+ after := func(n interface{}) {
+ if n == nil {
+ return
+ }
+ if false && reflect.TypeOf(n).Kind() == reflect.Ptr { // debugging trace
+ defer func() {
+ if t := typeof[n]; t != "" {
+ pos := fset.Position(n.(ast.Node).Pos())
+ fmt.Fprintf(os.Stderr, "%s: typeof[%s] = %s\n", pos, gofmt(n), t)
+ }
+ }()
+ }
+
+ switch n := n.(type) {
+ case *ast.FuncDecl, *ast.FuncLit:
+ // pop function type off stack
+ curfn = curfn[:len(curfn)-1]
+
+ case *ast.FuncType:
+ typeof[n] = mkType(joinFunc(split(typeof[n.Params]), split(typeof[n.Results])))
+
+ case *ast.FieldList:
+ // Field list is concatenation of sub-lists.
+ t := ""
+ for _, field := range n.List {
+ if t != "" {
+ t += ", "
+ }
+ t += typeof[field]
+ }
+ typeof[n] = t
+
+ case *ast.Field:
+ // Field is one instance of the type per name.
+ all := ""
+ t := typeof[n.Type]
+ if !isType(t) {
+ // Create a type, because it is typically *T or *p.T
+ // and we might care about that type.
+ t = mkType(gofmt(n.Type))
+ typeof[n.Type] = t
+ }
+ t = getType(t)
+ if len(n.Names) == 0 {
+ all = t
+ } else {
+ for _, id := range n.Names {
+ if all != "" {
+ all += ", "
+ }
+ all += t
+ typeof[id.Obj] = t
+ typeof[id] = t
+ }
+ }
+ typeof[n] = all
+
+ case *ast.ValueSpec:
+ // var declaration. Use type if present.
+ if n.Type != nil {
+ t := typeof[n.Type]
+ if !isType(t) {
+ t = mkType(gofmt(n.Type))
+ typeof[n.Type] = t
+ }
+ t = getType(t)
+ for _, id := range n.Names {
+ set(id, t, true)
+ }
+ }
+ // Now treat same as assignment.
+ typecheckAssign(makeExprList(n.Names), n.Values, true)
+
+ case *ast.AssignStmt:
+ typecheckAssign(n.Lhs, n.Rhs, n.Tok == token.DEFINE)
+
+ case *ast.Ident:
+ // Identifier can take its type from underlying object.
+ if t := typeof[n.Obj]; t != "" {
+ typeof[n] = t
+ }
+
+ case *ast.SelectorExpr:
+ // Field or method.
+ name := n.Sel.Name
+ if t := typeof[n.X]; t != "" {
+ if strings.HasPrefix(t, "*") {
+ t = t[1:] // implicit *
+ }
+ if typ := cfg.Type[t]; typ != nil {
+ if t := typ.dot(cfg, name); t != "" {
+ typeof[n] = t
+ return
+ }
+ }
+ tt := typeof[t+"."+name]
+ if isType(tt) {
+ typeof[n] = getType(tt)
+ return
+ }
+ }
+ // Package selector.
+ if x, ok := n.X.(*ast.Ident); ok && x.Obj == nil {
+ str := x.Name + "." + name
+ if cfg.Type[str] != nil {
+ typeof[n] = mkType(str)
+ return
+ }
+ if t := cfg.typeof(x.Name + "." + name); t != "" {
+ typeof[n] = t
+ return
+ }
+ }
+
+ case *ast.CallExpr:
+ // make(T) has type T.
+ if isTopName(n.Fun, "make") && len(n.Args) >= 1 {
+ typeof[n] = gofmt(n.Args[0])
+ return
+ }
+ // new(T) has type *T
+ if isTopName(n.Fun, "new") && len(n.Args) == 1 {
+ typeof[n] = "*" + gofmt(n.Args[0])
+ return
+ }
+ // Otherwise, use type of function to determine arguments.
+ t := typeof[n.Fun]
+ in, out := splitFunc(t)
+ if in == nil && out == nil {
+ return
+ }
+ typeof[n] = join(out)
+ for i, arg := range n.Args {
+ if i >= len(in) {
+ break
+ }
+ if typeof[arg] == "" {
+ typeof[arg] = in[i]
+ }
+ }
+
+ case *ast.TypeAssertExpr:
+ // x.(type) has type of x.
+ if n.Type == nil {
+ typeof[n] = typeof[n.X]
+ return
+ }
+ // x.(T) has type T.
+ if t := typeof[n.Type]; isType(t) {
+ typeof[n] = getType(t)
+ } else {
+ typeof[n] = gofmt(n.Type)
+ }
+
+ case *ast.SliceExpr:
+ // x[i:j] has type of x.
+ typeof[n] = typeof[n.X]
+
+ case *ast.IndexExpr:
+ // x[i] has key type of x's type.
+ t := expand(typeof[n.X])
+ if strings.HasPrefix(t, "[") || strings.HasPrefix(t, "map[") {
+ // Lazy: assume there are no nested [] in the array
+ // length or map key type.
+ if i := strings.Index(t, "]"); i >= 0 {
+ typeof[n] = t[i+1:]
+ }
+ }
+
+ case *ast.StarExpr:
+ // *x for x of type *T has type T when x is an expr.
+ // We don't use the result when *x is a type, but
+ // compute it anyway.
+ t := expand(typeof[n.X])
+ if isType(t) {
+ typeof[n] = "type *" + getType(t)
+ } else if strings.HasPrefix(t, "*") {
+ typeof[n] = t[len("*"):]
+ }
+
+ case *ast.UnaryExpr:
+ // &x for x of type T has type *T.
+ t := typeof[n.X]
+ if t != "" && n.Op == token.AND {
+ typeof[n] = "*" + t
+ }
+
+ case *ast.CompositeLit:
+ // T{...} has type T.
+ typeof[n] = gofmt(n.Type)
+
+ case *ast.ParenExpr:
+ // (x) has type of x.
+ typeof[n] = typeof[n.X]
+
+ case *ast.RangeStmt:
+ t := expand(typeof[n.X])
+ if t == "" {
+ return
+ }
+ var key, value string
+ if t == "string" {
+ key, value = "int", "rune"
+ } else if strings.HasPrefix(t, "[") {
+ key = "int"
+ if i := strings.Index(t, "]"); i >= 0 {
+ value = t[i+1:]
+ }
+ } else if strings.HasPrefix(t, "map[") {
+ if i := strings.Index(t, "]"); i >= 0 {
+ key, value = t[4:i], t[i+1:]
+ }
+ }
+ changed := false
+ if n.Key != nil && key != "" {
+ changed = true
+ set(n.Key, key, n.Tok == token.DEFINE)
+ }
+ if n.Value != nil && value != "" {
+ changed = true
+ set(n.Value, value, n.Tok == token.DEFINE)
+ }
+ // Ugly failure of vision: already type-checked body.
+ // Do it again now that we have that type info.
+ if changed {
+ typecheck1(cfg, n.Body, typeof, assign)
+ }
+
+ case *ast.TypeSwitchStmt:
+ // Type of variable changes for each case in type switch,
+ // but go/parser generates just one variable.
+ // Repeat type check for each case with more precise
+ // type information.
+ as, ok := n.Assign.(*ast.AssignStmt)
+ if !ok {
+ return
+ }
+ varx, ok := as.Lhs[0].(*ast.Ident)
+ if !ok {
+ return
+ }
+ t := typeof[varx]
+ for _, cas := range n.Body.List {
+ cas := cas.(*ast.CaseClause)
+ if len(cas.List) == 1 {
+ // Variable has specific type only when there is
+ // exactly one type in the case list.
+ if tt := typeof[cas.List[0]]; isType(tt) {
+ tt = getType(tt)
+ typeof[varx] = tt
+ typeof[varx.Obj] = tt
+ typecheck1(cfg, cas.Body, typeof, assign)
+ }
+ }
+ }
+ // Restore t.
+ typeof[varx] = t
+ typeof[varx.Obj] = t
+
+ case *ast.ReturnStmt:
+ if len(curfn) == 0 {
+ // Probably can't happen.
+ return
+ }
+ f := curfn[len(curfn)-1]
+ res := n.Results
+ if f.Results != nil {
+ t := split(typeof[f.Results])
+ for i := 0; i < len(res) && i < len(t); i++ {
+ set(res[i], t[i], false)
+ }
+ }
+ }
+ }
+ walkBeforeAfter(f, before, after)
+}
+
+// Convert between function type strings and lists of types.
+// Using strings makes this a little harder, but it makes
+// a lot of the rest of the code easier. This will all go away
+// when we can use go/typechecker directly.
+
+// splitFunc splits "func(x,y,z) (a,b,c)" into ["x", "y", "z"] and ["a", "b", "c"].
+func splitFunc(s string) (in, out []string) {
+ if !strings.HasPrefix(s, "func(") {
+ return nil, nil
+ }
+
+ i := len("func(") // index of beginning of 'in' arguments
+ nparen := 0
+ for j := i; j < len(s); j++ {
+ switch s[j] {
+ case '(':
+ nparen++
+ case ')':
+ nparen--
+ if nparen < 0 {
+ // found end of parameter list
+ out := strings.TrimSpace(s[j+1:])
+ if len(out) >= 2 && out[0] == '(' && out[len(out)-1] == ')' {
+ out = out[1 : len(out)-1]
+ }
+ return split(s[i:j]), split(out)
+ }
+ }
+ }
+ return nil, nil
+}
+
+// joinFunc is the inverse of splitFunc.
+func joinFunc(in, out []string) string {
+ outs := ""
+ if len(out) == 1 {
+ outs = " " + out[0]
+ } else if len(out) > 1 {
+ outs = " (" + join(out) + ")"
+ }
+ return "func(" + join(in) + ")" + outs
+}
+
+// split splits "int, float" into ["int", "float"] and splits "" into [].
+func split(s string) []string {
+ out := []string{}
+ i := 0 // current type being scanned is s[i:j].
+ nparen := 0
+ for j := 0; j < len(s); j++ {
+ switch s[j] {
+ case ' ':
+ if i == j {
+ i++
+ }
+ case '(':
+ nparen++
+ case ')':
+ nparen--
+ if nparen < 0 {
+ // probably can't happen
+ return nil
+ }
+ case ',':
+ if nparen == 0 {
+ if i < j {
+ out = append(out, s[i:j])
+ }
+ i = j + 1
+ }
+ }
+ }
+ if nparen != 0 {
+ // probably can't happen
+ return nil
+ }
+ if i < len(s) {
+ out = append(out, s[i:])
+ }
+ return out
+}
+
+// join is the inverse of split.
+func join(x []string) string {
+ return strings.Join(x, ", ")
+}
generated by cgit v1.2.3-1-g7c22 (git 2.25.1) at 2024-05-20 20:09:18 +0000