128 lines
3.2 KiB
Go
128 lines
3.2 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ssa
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// This file defines a number of miscellaneous utility functions.
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import (
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"fmt"
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"go/ast"
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"go/token"
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"io"
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"os"
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"golang.org/x/tools/astutil"
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"golang.org/x/tools/go/types"
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)
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func unreachable() {
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panic("unreachable")
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}
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//// AST utilities
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func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
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// isBlankIdent returns true iff e is an Ident with name "_".
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// They have no associated types.Object, and thus no type.
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//
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func isBlankIdent(e ast.Expr) bool {
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id, ok := e.(*ast.Ident)
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return ok && id.Name == "_"
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}
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//// Type utilities. Some of these belong in go/types.
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// isPointer returns true for types whose underlying type is a pointer.
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func isPointer(typ types.Type) bool {
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_, ok := typ.Underlying().(*types.Pointer)
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return ok
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}
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// isInterface reports whether T's underlying type is an interface.
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func isInterface(T types.Type) bool {
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_, ok := T.Underlying().(*types.Interface)
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return ok
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}
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// deref returns a pointer's element type; otherwise it returns typ.
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func deref(typ types.Type) types.Type {
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if p, ok := typ.Underlying().(*types.Pointer); ok {
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return p.Elem()
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}
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return typ
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}
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// recvType returns the receiver type of method obj.
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func recvType(obj *types.Func) types.Type {
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return obj.Type().(*types.Signature).Recv().Type()
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}
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// DefaultType returns the default "typed" type for an "untyped" type;
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// it returns the incoming type for all other types. The default type
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// for untyped nil is untyped nil.
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//
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// Exported to ssa/interp.
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//
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// TODO(gri): this is a copy of go/types.defaultType; export that function.
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//
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func DefaultType(typ types.Type) types.Type {
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if t, ok := typ.(*types.Basic); ok {
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k := t.Kind()
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switch k {
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case types.UntypedBool:
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k = types.Bool
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case types.UntypedInt:
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k = types.Int
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case types.UntypedRune:
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k = types.Rune
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case types.UntypedFloat:
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k = types.Float64
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case types.UntypedComplex:
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k = types.Complex128
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case types.UntypedString:
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k = types.String
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}
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typ = types.Typ[k]
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}
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return typ
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}
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// logStack prints the formatted "start" message to stderr and
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// returns a closure that prints the corresponding "end" message.
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// Call using 'defer logStack(...)()' to show builder stack on panic.
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// Don't forget trailing parens!
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//
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func logStack(format string, args ...interface{}) func() {
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msg := fmt.Sprintf(format, args...)
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io.WriteString(os.Stderr, msg)
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io.WriteString(os.Stderr, "\n")
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return func() {
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io.WriteString(os.Stderr, msg)
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io.WriteString(os.Stderr, " end\n")
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}
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}
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// newVar creates a 'var' for use in a types.Tuple.
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func newVar(name string, typ types.Type) *types.Var {
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return types.NewParam(token.NoPos, nil, name, typ)
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}
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// anonVar creates an anonymous 'var' for use in a types.Tuple.
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func anonVar(typ types.Type) *types.Var {
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return newVar("", typ)
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}
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var lenResults = types.NewTuple(anonVar(tInt))
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// makeLen returns the len builtin specialized to type func(T)int.
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func makeLen(T types.Type) *Builtin {
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lenParams := types.NewTuple(anonVar(T))
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return &Builtin{
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name: "len",
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sig: types.NewSignature(nil, nil, lenParams, lenResults, false),
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}
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}
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