Golang ast.Stmt类代码示例

// insertInWithin places before/after advice around a statement
func (wb *WithinBlock) insertInWithin(a ast.Stmt, w *Weave) string {
	rout := ""

	mName := grabMethodName(a)

	// begin line
	begin := wb.fset.Position(a.Pos()).Line - 1
	after := wb.fset.Position(a.End()).Line + 1

	// until this is refactored - any lines we add in our
	// advice need to be accounted for w/begin
	before_advice := formatAdvice(wb.aspect.advize.before, mName)
	after_advice := formatAdvice(wb.aspect.advize.after, mName)

	if before_advice != "" {
		rout = w.writeAtLine(wb.fname, begin+wb.linecnt, before_advice)
		wb.linecnt += strings.Count(before_advice, "\n") + 1
	}

	if after_advice != "" {
		rout = w.writeAtLine(wb.fname, after+wb.linecnt-1, after_advice)

		wb.linecnt += strings.Count(after_advice, "\n") + 1
	}

	for t := 0; t < len(wb.aspect.importz); t++ {
		wb.importsNeeded = append(wb.importsNeeded, wb.aspect.importz[t])
	}

	return rout
}

func (c *compiler) VisitStmt(stmt ast.Stmt) {
	if c.logger != nil {
		c.logger.Println("Compile statement:", reflect.TypeOf(stmt),
			"@", c.fileset.Position(stmt.Pos()))
	}
	switch x := stmt.(type) {
	case *ast.ReturnStmt:
		c.VisitReturnStmt(x)
	case *ast.AssignStmt:
		c.VisitAssignStmt(x)
	case *ast.IncDecStmt:
		c.VisitIncDecStmt(x)
	case *ast.IfStmt:
		c.VisitIfStmt(x)
	case *ast.ForStmt:
		c.VisitForStmt(x)
	case *ast.ExprStmt:
		c.VisitExpr(x.X)
	case *ast.BlockStmt:
		c.VisitBlockStmt(x)
	case *ast.DeclStmt:
		c.VisitDecl(x.Decl)
	case *ast.GoStmt:
		c.VisitGoStmt(x)
	case *ast.SwitchStmt:
		c.VisitSwitchStmt(x)
	default:
		panic(fmt.Sprintf("Unhandled Stmt node: %s", reflect.TypeOf(stmt)))
	}
}

// statementBoundary finds the location in s that terminates the current basic
// block in the source.
func (f *File) statementBoundary(s ast.Stmt) token.Pos {
	// Control flow statements are easy.
	switch s := s.(type) {
	case *ast.BlockStmt:
		// Treat blocks like basic blocks to avoid overlapping counters.
		return s.Lbrace
	case *ast.IfStmt:
		return s.Body.Lbrace
	case *ast.ForStmt:
		return s.Body.Lbrace
	case *ast.LabeledStmt:
		return f.statementBoundary(s.Stmt)
	case *ast.RangeStmt:
		return s.Body.Lbrace
	case *ast.SwitchStmt:
		return s.Body.Lbrace
	case *ast.SelectStmt:
		return s.Body.Lbrace
	case *ast.TypeSwitchStmt:
		return s.Body.Lbrace
	}
	// If not a control flow statement, it is a declaration, expression, call, etc. and it may have a function literal.
	// If it does, that's tricky because we want to exclude the body of the function from this block.
	// Draw a line at the start of the body of the first function literal we find.
	// TODO: what if there's more than one? Probably doesn't matter much.
	var literal funcLitFinder
	ast.Walk(&literal, s)
	if literal.found() {
		return token.Pos(literal)
	}
	return s.End()
}

func emitTraceStmt(f *Function, event TraceEvent, syntax ast.Stmt) Value {
	t := &Trace{
		Event:      event,
		Start:      syntax.Pos(),
		End:        syntax.End(),
		Breakpoint: false,
		syntax:     syntax,
	}
	return emitTraceCommon(f, t)
}

func (p *parser) makeExpr(s ast.Stmt) ast.Expr {
	if s == nil {
		return nil
	}
	if es, isExpr := s.(*ast.ExprStmt); isExpr {
		return p.checkExpr(es.X)
	}
	p.Error(s.Pos(), "expected condition, found simple statement")
	return &ast.BadExpr{s.Pos()}
}

func (v *ShortError) VisitStmt(scope *ast.Scope, stmt ast.Stmt) ScopeVisitor {
	v.stmt = stmt
	switch stmt := stmt.(type) {
	case *ast.BlockStmt:
		return &ShortError{v.file, v.patches, v.stmt, stmt, 0, new([]byte)}
	case *ast.ExprStmt:
		if call := calltomust(stmt.X); call != nil {
			// TODO(elazarl): depends on number of variables it returns, currently we assume one
			pos := v.file.Fset.Position(stmt.Pos())
			fmt.Printf("%s:%d:%d: 'must' builtin must be assigned into variable\n",
				pos.Filename, pos.Line, pos.Column)
		}
	case *ast.AssignStmt:
		if len(stmt.Rhs) != 1 {
			return v
		}
		if rhs, ok := stmt.Rhs[0].(*ast.CallExpr); ok {
			if fun, ok := rhs.Fun.(*ast.Ident); ok && fun.Name == MustKeyword {
				if stmt.Tok == token.DEFINE {
					tmpVar := v.tempVar("assignerr_", scope)
					*v.patches = append(*v.patches,
						patch.Insert(stmt.TokPos, ", "+tmpVar+" "),
						patch.Replace(fun, ""),
						patch.Insert(stmt.End(),
							"; if "+tmpVar+" != nil "+
								"{ panic("+tmpVar+") };"),
					)
					for _, arg := range rhs.Args {
						v.VisitExpr(scope, arg)
					}
					return nil
				} else if stmt.Tok == token.ASSIGN {
					vars := []string{}
					for i := 0; i < len(stmt.Lhs); i++ {
						vars = append(vars, v.tempVar(fmt.Sprint("assgn", i, "_"), scope))
					}
					assgnerr := v.tempVar("assgnErr_", scope)

					*v.patches = append(*v.patches,
						patch.Insert(stmt.Pos(),
							strings.Join(append(vars, assgnerr), ", ")+":="),
						patch.InsertNode(stmt.Pos(), rhs.Args[0]),
						patch.Insert(stmt.Pos(),
							"; if "+assgnerr+" != nil "+
								"{ panic("+assgnerr+") };"),
						patch.Replace(rhs, strings.Join(vars, ", ")),
					)
					v.VisitExpr(scope, rhs.Args[0])
					return nil
				}
			}
		}
	}
	return v
}

func (v *visitor) wrapLoop(node ast.Stmt, body *ast.BlockStmt) (block *ast.BlockStmt, loop ast.Stmt) {
	block = astPrintf(`
		{
			scope := %s.EnteringNewChildScope()
			_ = scope // placeholder
			godebug.Line(ctx, scope, %s)
		}`, v.scopeVar, pos2lineString(node.Pos()))[0].(*ast.BlockStmt)
	block.List[1] = node
	loop = node
	return
}

func (f *File) validStmt(stmt ast.Stmt) *Error {
	if stmt == nil {
		return nil
	}
	if assign, ok := stmt.(*ast.AssignStmt); ok {
		if len(assign.Lhs) != 1 || len(assign.Rhs) != 1 {
			return &Error{errors.New("Invalid assigment statment"), assign.Pos()}
		}
		return nil
	}
	if ifstmt, ok := stmt.(*ast.IfStmt); ok {
		if err := f.validExpr(ifstmt.Cond); err != nil {
			return err
		}
		// initialization clause not allowed for if statements
		if ifstmt.Init != nil {
			return &Error{errors.New("ifstmt cannot have initialization clause"), ifstmt.Init.Pos()}
		}
		if err := f.validStmt(ifstmt.Body); err != nil {
			return err
		}
		if err := f.validStmt(ifstmt.Else); err != nil {
			return err
		}
	}
	if blk, ok := stmt.(*ast.BlockStmt); ok {
		for _, s := range blk.List {
			if err := f.validStmt(s); err != nil {
				return err
			}
		}
	}
	if _, ok := stmt.(*ast.EmptyStmt); ok {
		return nil
	}
	if ret, ok := stmt.(*ast.ReturnStmt); ok {
		if ret.Results == nil || len(ret.Results) == 0 {
			return nil
		}
		if len(ret.Results) > 1 {
			return &Error{errors.New("Return statement doesn't allow multiple return values"), ret.Pos()}
		}
		return f.validRetExpr(ret.Results[0])
	}
	if indec, ok := stmt.(*ast.IncDecStmt); ok {
		// TODO specialize
		if err := f.validExpr(indec.X); err != nil {
			return err
		}
	}
	return &Error{errors.New(fmt.Sprintf("Invalid stmt:%v", stmt)), stmt.Pos()}
}

func generateCheckedAssign(stmt ast.Stmt, place ast.Expr) ast.Stmt {
	pos := stmt.Pos()
	return &ast.IfStmt{
		If:   pos,
		Init: stmt,
		Cond: &ast.BinaryExpr{
			X:     place,
			OpPos: pos,
			Op:    token.NEQ,
			Y:     ast.NewIdent("nil")},
		Body: &ast.BlockStmt{
			Lbrace: pos,
			List:   []ast.Stmt{&ast.ReturnStmt{}},
			Rbrace: pos},
	}
}

func (check *checker) multipleDefaults(list []ast.Stmt) {
	var first ast.Stmt
	for _, s := range list {
		var d ast.Stmt
		switch c := s.(type) {
		case *ast.CaseClause:
			if len(c.List) == 0 {
				d = s
			}
		case *ast.CommClause:
			if c.Comm == nil {
				d = s
			}
		default:
			check.invalidAST(s.Pos(), "case/communication clause expected")
		}
		if d != nil {
			if first != nil {
				check.errorf(d.Pos(), "multiple defaults (first at %s)", first.Pos())
			} else {
				first = d
			}
		}
	}
}

func (t *rewriteVisitor) rewriteRecvStmt(stmt ast.Stmt) []ast.Stmt {
	// Prohibit inner blocks from having channel operation nodes
	switch q := stmt.(type) {
	case *ast.AssignStmt:
		for _, expr := range q.Lhs {
			// TODO: Handle channel operations inside LHS of assignments
			RecurseProhibit(t, expr)
		}
		for _, expr := range q.Rhs {
			if expr == nil {
				continue
			}
			// TODO: Handle channel operations inside RHS of assignments
			if ue := filterRecvExpr(expr); ue != nil {
				RecurseProhibit(t, ue.X)
			} else {
				RecurseProhibit(t, expr)
			}
		}
	case *ast.ExprStmt:
		if q == nil {
			break
		}
		// TODO: Handle channel operations inside RHS of assignments
		if ue := filterRecvExpr(q.X); ue != nil {
			RecurseProhibit(t, ue.X)
		} else {
			RecurseProhibit(t, q)
		}
	default:
		panic("unreach")
	}
	// Rewrite receive statement itself
	return []ast.Stmt{
		makeSimpleCallStmt("vtime", "Block", stmt.Pos()),
		stmt,
		makeSimpleCallStmt("vtime", "Unblock", stmt.Pos()),
	}
}

// compiles a statement
func (w *World) compileStmt(st ast.Stmt) Expr {
	switch st := st.(type) {
	default:
		panic(err(st.Pos(), "not allowed:", typ(st)))
	case *ast.EmptyStmt:
		return &emptyStmt{}
	case *ast.AssignStmt:
		return w.compileAssignStmt(st)
	case *ast.ExprStmt:
		return w.compileExpr(st.X)
	case *ast.IfStmt:
		return w.compileIfStmt(st)
	case *ast.ForStmt:
		return w.compileForStmt(st)
	case *ast.IncDecStmt:
		return w.compileIncDecStmt(st)
	case *ast.BlockStmt:
		w.EnterScope()
		defer w.ExitScope()
		return w.compileBlockStmt_noScope(st)
	}
}

// statementBoundary finds the location in s that terminates the current basic
// block in the source.
func (f *File) statementBoundary(s ast.Stmt) token.Pos {
	// Control flow statements are easy.
	switch s := s.(type) {
	case *ast.BlockStmt:
		// Treat blocks like basic blocks to avoid overlapping counters.
		return s.Lbrace
	case *ast.IfStmt:
		return s.Body.Lbrace
	case *ast.ForStmt:
		return s.Body.Lbrace
	case *ast.LabeledStmt:
		return f.statementBoundary(s.Stmt)
	case *ast.RangeStmt:
		// Ranges might loop over things with function literals.: for _ = range []func(){ ... } {.
		// TODO: There are a few other such possibilities, but they're extremely unlikely.
		found, pos := hasFuncLiteral(s.X)
		if found {
			return pos
		}
		return s.Body.Lbrace
	case *ast.SwitchStmt:
		return s.Body.Lbrace
	case *ast.SelectStmt:
		return s.Body.Lbrace
	case *ast.TypeSwitchStmt:
		return s.Body.Lbrace
	}
	// If not a control flow statement, it is a declaration, expression, call, etc. and it may have a function literal.
	// If it does, that's tricky because we want to exclude the body of the function from this block.
	// Draw a line at the start of the body of the first function literal we find.
	// TODO: what if there's more than one? Probably doesn't matter much.
	found, pos := hasFuncLiteral(s)
	if found {
		return pos
	}
	return s.End()
}

// stmt typechecks statement s.
func (check *checker) stmt(s ast.Stmt) {
	switch s := s.(type) {
	case *ast.BadStmt, *ast.EmptyStmt:
		// ignore

	case *ast.DeclStmt:
		d, _ := s.Decl.(*ast.GenDecl)
		if d == nil || (d.Tok != token.CONST && d.Tok != token.TYPE && d.Tok != token.VAR) {
			check.invalidAST(token.NoPos, "const, type, or var declaration expected")
			return
		}
		if d.Tok == token.CONST {
			check.assocInitvals(d)
		}
		check.decl(d)

	case *ast.LabeledStmt:
		// TODO(gri) anything to do with label itself?
		check.stmt(s.Stmt)

	case *ast.ExprStmt:
		var x operand
		used := false
		switch e := unparen(s.X).(type) {
		case *ast.CallExpr:
			// function calls are permitted
			used = true
			// but some builtins are excluded
			// (Caution: This evaluates e.Fun twice, once here and once
			//           below as part of s.X. This has consequences for
			//           check.register. Perhaps this can be avoided.)
			check.expr(&x, e.Fun, nil, -1)
			if x.mode != invalid {
				if b, ok := x.typ.(*builtin); ok && !b.isStatement {
					used = false
				}
			}
		case *ast.UnaryExpr:
			// receive operations are permitted
			if e.Op == token.ARROW {
				used = true
			}
		}
		if !used {
			check.errorf(s.Pos(), "%s not used", s.X)
			// ok to continue
		}
		check.rawExpr(&x, s.X, nil, -1, false)
		if x.mode == typexpr {
			check.errorf(x.pos(), "%s is not an expression", &x)
		}

	case *ast.SendStmt:
		var ch, x operand
		check.expr(&ch, s.Chan, nil, -1)
		check.expr(&x, s.Value, nil, -1)
		if ch.mode == invalid || x.mode == invalid {
			return
		}
		if tch, ok := underlying(ch.typ).(*Chan); !ok || tch.Dir&ast.SEND == 0 || !check.assignment(&x, tch.Elt) {
			if x.mode != invalid {
				check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
			}
		}

	case *ast.IncDecStmt:
		var op token.Token
		switch s.Tok {
		case token.INC:
			op = token.ADD
		case token.DEC:
			op = token.SUB
		default:
			check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
			return
		}
		var x operand
		Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
		check.binary(&x, s.X, Y, op, -1)
		if x.mode == invalid {
			return
		}
		check.assign1to1(s.X, nil, &x, false, -1)

	case *ast.AssignStmt:
		switch s.Tok {
		case token.ASSIGN, token.DEFINE:
			if len(s.Lhs) == 0 {
				check.invalidAST(s.Pos(), "missing lhs in assignment")
				return
			}
			check.assignNtoM(s.Lhs, s.Rhs, s.Tok == token.DEFINE, -1)
		default:
			// assignment operations
			if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
				check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
				return
			}
			// TODO(gri) make this conversion more efficient
//.........这里部分代码省略.........

// stmt typechecks statement s.
func (check *checker) stmt(ctxt stmtContext, s ast.Stmt) {
	// statements cannot use iota in general
	// (constant declarations set it explicitly)
	assert(check.iota == nil)

	// statements must end with the same top scope as they started with
	if debug {
		defer func(scope *Scope) {
			// don't check if code is panicking
			if p := recover(); p != nil {
				panic(p)
			}
			assert(scope == check.topScope)
		}(check.topScope)
	}

	inner := ctxt &^ fallthroughOk
	switch s := s.(type) {
	case *ast.BadStmt, *ast.EmptyStmt:
		// ignore

	case *ast.DeclStmt:
		check.declStmt(s.Decl)

	case *ast.LabeledStmt:
		check.hasLabel = true
		check.stmt(ctxt, s.Stmt)

	case *ast.ExprStmt:
		// spec: "With the exception of specific built-in functions,
		// function and method calls and receive operations can appear
		// in statement context. Such statements may be parenthesized."
		var x operand
		kind := check.rawExpr(&x, s.X, nil)
		var msg string
		switch x.mode {
		default:
			if kind == statement {
				return
			}
			msg = "is not used"
		case builtin:
			msg = "must be called"
		case typexpr:
			msg = "is not an expression"
		}
		check.errorf(x.pos(), "%s %s", &x, msg)

	case *ast.SendStmt:
		var ch, x operand
		check.expr(&ch, s.Chan)
		check.expr(&x, s.Value)
		if ch.mode == invalid || x.mode == invalid {
			return
		}
		if tch, ok := ch.typ.Underlying().(*Chan); !ok || tch.dir&ast.SEND == 0 || !check.assignment(&x, tch.elem) {
			if x.mode != invalid {
				check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
			}
		}

	case *ast.IncDecStmt:
		var op token.Token
		switch s.Tok {
		case token.INC:
			op = token.ADD
		case token.DEC:
			op = token.SUB
		default:
			check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
			return
		}
		var x operand
		Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
		check.binary(&x, s.X, Y, op)
		if x.mode == invalid {
			return
		}
		check.assignVar(s.X, &x)

	case *ast.AssignStmt:
		switch s.Tok {
		case token.ASSIGN, token.DEFINE:
			if len(s.Lhs) == 0 {
				check.invalidAST(s.Pos(), "missing lhs in assignment")
				return
			}
			if s.Tok == token.DEFINE {
				check.shortVarDecl(s.TokPos, s.Lhs, s.Rhs)
			} else {
				// regular assignment
				check.assignVars(s.Lhs, s.Rhs)
			}

		default:
			// assignment operations
			if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
				check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
				return
//.........这里部分代码省略.........