Golang ast.BlockStmt类代码示例

// Sets multiLine to true if the function body spans multiple lines.
func (p *printer) funcBody(b *ast.BlockStmt, headerSize int, isLit bool, multiLine *bool) {
	if b == nil {
		return
	}

	p.nesting++
	defer func() {
		p.nesting--
	}()

	if p.isOneLineFunc(b, headerSize) {
		sep := vtab
		if isLit {
			sep = blank
		}
		p.print(sep, b.Pos(), token.LBRACE)
		if len(b.List) > 0 {
			p.print(blank)
			for i, s := range b.List {
				if i > 0 {
					p.print(token.SEMICOLON, blank)
				}
				p.stmt(s, i == len(b.List)-1, ignoreMultiLine)
			}
			p.print(blank)
		}
		p.print(b.Rbrace, token.RBRACE)
		return
	}

	p.print(blank)
	p.block(b, 1)
	*multiLine = true
}

func rewriteFnWithRecovers(body *ast.BlockStmt, fnType *ast.FuncType) (wrapped *ast.FuncLit) {
	// The formatting of the channel declaration is ugly, but it's presented this way here to show how it will look in the actual output.
	// As far as I know, I would need to set the token.Pos values for the left and right braces of the struct and interface type literals
	// in order to get them on one line, but I don't think I can do that without computing all of the other token.Pos values for everything
	// else I generate.
	// TODO: These identifiers will probably conflict if there is a nested function that also has unnamed outputs. Should probably make a better gensym.
	outputDecls, outputs := inputsOrOutputs(fnType.Results, idents.result)
	if len(outputs) > 0 {
		body.List = astPrintf(`%s = func() (%s) {%s}()`, outputs, fnType.Results, body.List)
	}
	body.List = astPrintf(`
		{{%s}}
		_r := make(chan chan interface {
		})
		recovers, panicChan := godebug.EnterFuncWithRecovers(_r, func(ctx *godebug.Context) {
			%s
		})
		for recoverChan := range recovers {
			recoverChan <- recover()
		}
		if panicVal, ok := <-panicChan; ok {
			panic(panicVal)
		}
		{{return %s}}`, outputDecls, body.List, outputs)
	body.Rbrace = token.NoPos // without this I was getting extra whitespace at the end of the function
	return wrapped
}

// labels checks correct label use in body.
func (check *Checker) labels(body *ast.BlockStmt) {
	// set of all labels in this body
	all := NewScope(nil, body.Pos(), body.End(), "label")

	fwdJumps := check.blockBranches(all, nil, nil, body.List)

	// If there are any forward jumps left, no label was found for
	// the corresponding goto statements. Either those labels were
	// never defined, or they are inside blocks and not reachable
	// for the respective gotos.
	for _, jmp := range fwdJumps {
		var msg string
		name := jmp.Label.Name
		if alt := all.Lookup(name); alt != nil {
			msg = "goto %s jumps into block"
			alt.(*Label).used = true // avoid another error
		} else {
			msg = "label %s not declared"
		}
		check.errorf(jmp.Label.Pos(), msg, name)
	}

	// spec: "It is illegal to define a label that is never used."
	for _, obj := range all.elems {
		if lbl := obj.(*Label); !lbl.used {
			check.softErrorf(lbl.pos, "label %s declared but not used", lbl.name)
		}
	}
}

func (p *parser) parseBlock(n *parse.Node, scope *ast.Scope) *ast.BlockStmt {
	block := ast.BlockStmt{
		Lbrace: token.Pos(n.Child(0).Pos()),
		Rbrace: token.Pos(n.LastChild().Pos()),
	}
	eachListItem(stmt, n.Child(1), func(item *parse.Node) {
		block.List = append(block.List, p.parseStmt(item))
	})
	return &block
}

func (c *compiler) createBlockMetadata(stmt *ast.BlockStmt) llvm.DebugDescriptor {
	uniqueId++
	file := c.fileset.File(stmt.Pos())
	fd := llvm.FileDescriptor(file.Name())
	return &llvm.BlockDescriptor{
		File:    &fd,
		Line:    uint32(file.Line(stmt.Pos())),
		Context: c.currentDebugContext(),
		Id:      uniqueId,
	}
}

// block prints an *ast.BlockStmt; it always spans at least two lines.
func (p *printer) block(s *ast.BlockStmt, indent int, moveComments bool) {
	if moveComments {
		p.print(p.beforeComment(s.Pos()))
	} else {
		p.print(s.Pos())
	}
	p.print(token.LBRACE)
	p.stmtList(s.List, indent)
	p.linebreak(s.Rbrace.Line, 1, maxStmtNewlines, ignore, true)
	p.print(s.Rbrace, token.RBRACE)
}

// lastComment returns the last comment inside the provided block.
func lastComment(b *ast.BlockStmt, c []*ast.CommentGroup) (i int, last *ast.CommentGroup) {
	pos, end := b.Pos(), b.End()
	for j, cg := range c {
		if cg.Pos() < pos {
			continue
		}
		if cg.End() > end {
			break
		}
		i, last = j, cg
	}
	return
}

func (v *visitor) finalizeLoop(pos token.Pos, body *ast.BlockStmt) {
	if body == nil {
		return
	}
	line := pos2line(pos)
	if len(v.newIdents) == 0 {
		call := newCall(idents.godebug, "Line", ast.NewIdent(idents.ctx), ast.NewIdent(v.scopeVar), newInt(line))
		body.List = append(body.List, &ast.ExprStmt{X: call})
	} else {
		body.List = append([]ast.Stmt{
			astPrintf(`godebug.Line(ctx, scope, %s)`, strconv.Itoa(line))[0],
			newDeclareCall(idents.scope, v.newIdents),
		}, body.List...)
	}
}

func (lp *linePrinter) trimBlock(stmt *ast.BlockStmt) *ast.BlockStmt {
	if !lp.trim(stmt) {
		return lp.emptyBlock(stmt)
	}
	stmt.Rbrace = stmt.Lbrace
	return stmt
}

// New returns a new control-flow graph for the specified function body,
// which must be non-nil.
//
// The CFG builder calls mayReturn to determine whether a given function
// call may return.  For example, calls to panic, os.Exit, and log.Fatal
// do not return, so the builder can remove infeasible graph edges
// following such calls.  The builder calls mayReturn only for a
// CallExpr beneath an ExprStmt.
func New(body *ast.BlockStmt, mayReturn func(*ast.CallExpr) bool) *CFG {
	b := builder{
		mayReturn: mayReturn,
		cfg:       new(CFG),
	}
	b.current = b.newBlock("entry")
	b.stmt(body)

	// Does control fall off the end of the function's body?
	// Make implicit return explicit.
	if b.current != nil && !b.current.unreachable {
		b.add(&ast.ReturnStmt{
			Return: body.End() - 1,
		})
	}

	return b.cfg
}

func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body *ast.BlockStmt) {
	if trace {
		if name == "" {
			name = "<function literal>"
		}
		fmt.Printf("--- %s: %s {\n", name, sig)
		defer fmt.Println("--- <end>")
	}

	// set function scope extent
	sig.scope.pos = body.Pos()
	sig.scope.end = body.End()

	// save/restore current context and setup function context
	// (and use 0 indentation at function start)
	defer func(ctxt context, indent int) {
		check.context = ctxt
		check.indent = indent
	}(check.context, check.indent)
	check.context = context{
		decl:  decl,
		scope: sig.scope,
		sig:   sig,
	}
	check.indent = 0

	check.stmtList(0, body.List)

	if check.hasLabel {
		check.labels(body)
	}

	if sig.results.Len() > 0 && !check.isTerminating(body, "") {
		check.error(body.Rbrace, "missing return")
	}

	// spec: "Implementation restriction: A compiler may make it illegal to
	// declare a variable inside a function body if the variable is never used."
	// (One could check each scope after use, but that distributes this check
	// over several places because CloseScope is not always called explicitly.)
	check.usage(sig.scope)
}

// filterBlocks keeps the statements that are need to calculate MappedCells.
func filterBlock(blk *ast.BlockStmt, filterIDs map[string]bool,
	imports map[string]string) (*ast.BlockStmt, []dictKey) {

	dicts := dictionaries(blk, imports)

	usedDks := make(map[dictKey]bool)
	filtered := make([]ast.Stmt, 0, len(blk.List))
	for i := len(blk.List) - 1; i >= 0; i-- {
		switch s := blk.List[i].(type) {
		// TODO(soheil): Support switches.
		case *ast.SwitchStmt:
		// TODO(soheil): Add support for ifs.
		case *ast.IfStmt:
		default:
			// TODO(soheil): It's actually more complicated that. What about
			// functional calls, what about multiple return values, ...?
			dks, yes := accessesDict(s, dicts)
			if yes {
				for _, dk := range dks {
					filterIDs[dk.k] = true
					usedDks[dk] = true
				}
				continue
			}

			dirty := false
			rIDs, wIDs := ids(s)
			for _, id := range wIDs {
				if filterIDs[id] {
					dirty = true
					break
				}
			}

			if !dirty {
				continue
			}

			for _, id := range rIDs {
				filterIDs[id] = true
			}

			filtered = append([]ast.Stmt{s}, filtered...)
		}
	}

	blk.List = filtered

	keys := make([]dictKey, 0, len(usedDks))
	for dk, _ := range usedDks {
		keys = append(keys, dk)
	}
	return blk, keys
}

// bodySize is like nodeSize but it is specialized for *ast.BlockStmt's.
func (p *printer) bodySize(b *ast.BlockStmt, maxSize int) int {
	pos1 := b.Pos()
	pos2 := b.Rbrace
	if pos1.IsValid() && pos2.IsValid() && p.lineFor(pos1) != p.lineFor(pos2) {
		// opening and closing brace are on different lines - don't make it a one-liner
		return maxSize + 1
	}
	if len(b.List) > 5 || p.commentBefore(p.posFor(pos2)) {
		// too many statements or there is a comment inside - don't make it a one-liner
		return maxSize + 1
	}
	// otherwise, estimate body size
	bodySize := 0
	for i, s := range b.List {
		if i > 0 {
			bodySize += 2 // space for a semicolon and blank
		}
		bodySize += p.nodeSize(s, maxSize)
	}
	return bodySize
}

/*
 * Given a test func named TestDoesSomethingNeat, rewrites it as
 * It("does something neat", func() { __test_body_here__ }) and adds it
 * to the Describe's list of statements
 */
func rewriteTestFuncAsItStatement(testFunc *ast.FuncDecl, rootNode *ast.File, describe *ast.CallExpr) {
	var funcIndex int = -1
	for index, child := range rootNode.Decls {
		if child == testFunc {
			funcIndex = index
			break
		}
	}

	if funcIndex < 0 {
		panic(fmt.Sprintf("Assert failed: Error finding index for test node %s\n", testFunc.Name.Name))
	}

	var block *ast.BlockStmt = blockStatementFromDescribe(describe)
	block.List = append(block.List, createItStatementForTestFunc(testFunc))
	replaceTestingTsWithGinkgoT(block, namedTestingTArg(testFunc))

	// remove the old test func from the root node's declarations
	rootNode.Decls = append(rootNode.Decls[:funcIndex], rootNode.Decls[funcIndex+1:]...)
	return
}

func (p *printer) isOneLineFunc(b *ast.BlockStmt, headerSize int) bool {
	pos1 := b.Pos()
	pos2 := b.Rbrace
	if pos1.IsValid() && pos2.IsValid() && pos1.Line != pos2.Line {
		// opening and closing brace are on different lines - don't make it a one-liner
		return false
	}
	if len(b.List) > 5 || p.commentBefore(pos2) {
		// too many statements or there is a comment inside - don't make it a one-liner
		return false
	}
	// otherwise, estimate body size
	const maxSize = 100
	bodySize := 0
	for i, s := range b.List {
		if i > 0 {
			bodySize += 2 // space for a semicolon and blank
		}
		bodySize += p.nodeSize(s, maxSize)
	}
	return headerSize+bodySize <= maxSize
}