python-doc-tw.github.io/library/ast.html at master · python-doc-tw/python-doc-tw.github.io

History

582 lines (516 loc) · 39.3 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<head>

<title>33.2. ast — Abstract Syntax Trees — Python 3.7.0 說明文件</title>

title="在 Python 3.7.0 說明文件中搜尋"

href="../_static/opensearch.xml"/>

</head><body>

<ul>

<a href="../genindex.html" title="General Index"

accesskey="I">索引</a></li>

<a href="../py-modindex.html" title="Python 模組索引"

>模組</a> |</li>

<a href="symtable.html" title="33.3. symtable — Access to the compiler’s symbol tables"

accesskey="N">下一頁</a> |</li>

<a href="parser.html" title="33.1. parser — Access Python parse trees"

accesskey="P">上一頁</a> |</li>

<li><img src="../_static/py.png" alt=""

style="vertical-align: middle; margin-top: -1px"/></li>

<li><a href="https://www.python.org/">Python</a> »</li>

<li>

zh_TW

3.7.0

<a href="../index.html">Documentation </a> »

</li>

<li class="nav-item nav-item-1"><a href="index.html" >Python 標準函式庫 (Standard Library)</a> »</li>

<li class="nav-item nav-item-2"><a href="language.html" accesskey="U">33. Python Language Services</a> »</li>

</form>

</div>

</li>

</ul>

</div>

<h1>33.2. <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> — Abstract Syntax Trees<a class="headerlink" href="#module-ast" title="本標題的永久連結">¶</a></h1>

Source code: <a class="reference external" href="https://github.com/python/cpython/tree/3.7/Lib/ast.py">Lib/ast.py</a>

The <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> module helps Python applications to process trees of the Python

abstract syntax grammar. The abstract syntax itself might change with each

Python release; this module helps to find out programmatically what the current

grammar looks like.

An abstract syntax tree can be generated by passing <code class="xref py py-data docutils literal notranslate">ast.PyCF_ONLY_AST</code> as

a flag to the <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a> built-in function, or using the <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">parse()</code></a>

helper provided in this module. The result will be a tree of objects whose

classes all inherit from <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">ast.AST</code></a>. An abstract syntax tree can be

compiled into a Python code object using the built-in <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a> function.

<h2>33.2.1. Node classes<a class="headerlink" href="#node-classes" title="本標題的永久連結">¶</a></h2>

class <code class="descclassname">ast.</code><code class="descname">AST</code><a class="headerlink" href="#ast.AST" title="本定義的永久連結">¶</a></dt>

<dd>This is the base of all AST node classes. The actual node classes are

derived from the <code class="file docutils literal notranslate">Parser/Python.asdl</code> file, which is reproduced

<a class="reference internal" href="#abstract-grammar">below</a>. They are defined in the <code class="xref py py-mod docutils literal notranslate">_ast</code> C

module and re-exported in <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a>.

There is one class defined for each left-hand side symbol in the abstract

grammar (for example, <code class="xref py py-class docutils literal notranslate">ast.stmt</code> or <code class="xref py py-class docutils literal notranslate">ast.expr</code>). In addition,

there is one class defined for each constructor on the right-hand side; these

classes inherit from the classes for the left-hand side trees. For example,

<code class="xref py py-class docutils literal notranslate">ast.BinOp</code> inherits from <code class="xref py py-class docutils literal notranslate">ast.expr</code>. For production rules

with alternatives (aka 「sums」), the left-hand side class is abstract: only

instances of specific constructor nodes are ever created.

<code class="descname">_fields</code><a class="headerlink" href="#ast.AST._fields" title="本定義的永久連結">¶</a></dt>

<dd>Each concrete class has an attribute <a class="reference internal" href="#ast.AST._fields" title="ast.AST._fields"><code class="xref py py-attr docutils literal notranslate">_fields</code></a> which gives the names

of all child nodes.

Each instance of a concrete class has one attribute for each child node,

of the type as defined in the grammar. For example, <code class="xref py py-class docutils literal notranslate">ast.BinOp</code>

instances have an attribute <code class="xref py py-attr docutils literal notranslate">left</code> of type <code class="xref py py-class docutils literal notranslate">ast.expr</code>.

If these attributes are marked as optional in the grammar (using a

question mark), the value might be <code class="docutils literal notranslate">None</code>. If the attributes can have

zero-or-more values (marked with an asterisk), the values are represented

as Python lists. All possible attributes must be present and have valid

values when compiling an AST with <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>.

</dd></dl>

<code class="descname">lineno</code><a class="headerlink" href="#ast.AST.lineno" title="本定義的永久連結">¶</a></dt>

<code class="descname">col_offset</code><a class="headerlink" href="#ast.AST.col_offset" title="本定義的永久連結">¶</a></dt>

<dd>Instances of <code class="xref py py-class docutils literal notranslate">ast.expr</code> and <code class="xref py py-class docutils literal notranslate">ast.stmt</code> subclasses have

<a class="reference internal" href="#ast.AST.lineno" title="ast.AST.lineno"><code class="xref py py-attr docutils literal notranslate">lineno</code></a> and <a class="reference internal" href="#ast.AST.col_offset" title="ast.AST.col_offset"><code class="xref py py-attr docutils literal notranslate">col_offset</code></a> attributes. The <a class="reference internal" href="#ast.AST.lineno" title="ast.AST.lineno"><code class="xref py py-attr docutils literal notranslate">lineno</code></a> is

the line number of source text (1-indexed so the first line is line 1) and

the <a class="reference internal" href="#ast.AST.col_offset" title="ast.AST.col_offset"><code class="xref py py-attr docutils literal notranslate">col_offset</code></a> is the UTF-8 byte offset of the first token that

generated the node. The UTF-8 offset is recorded because the parser uses

UTF-8 internally.

</dd></dl>

The constructor of a class <code class="xref py py-class docutils literal notranslate">ast.T</code> parses its arguments as follows:

<li>If there are positional arguments, there must be as many as there are items

in <code class="xref py py-attr docutils literal notranslate">T._fields</code>; they will be assigned as attributes of these names.</li>

<li>If there are keyword arguments, they will set the attributes of the same

names to the given values.</li>

</ul>

For example, to create and populate an <code class="xref py py-class docutils literal notranslate">ast.UnaryOp</code> node, you could

use

node.op = ast.USub()

node.operand = ast.Num()

node.operand.n = 5

node.operand.lineno = 0

node.operand.col_offset = 0

node.lineno = 0

node.col_offset = 0

</pre></div>

</div>

or the more compact

<div class="highlight-python3 notranslate"><div class="highlight"><pre>node = ast.UnaryOp(ast.USub(), ast.Num(5, lineno=0, col_offset=0),

lineno=0, col_offset=0)

</pre></div>

</div>

</dd></dl>

</div>

<h2>33.2.2. Abstract Grammar<a class="headerlink" href="#abstract-grammar" title="本標題的永久連結">¶</a></h2>

The abstract grammar is currently defined as follows:

<div class="highlight-none notranslate"><div class="highlight"><pre>-- ASDL's 7 builtin types are:

-- identifier, int, string, bytes, object, singleton, constant

-- singleton: None, True or False

-- constant can be None, whereas None means "no value" for object.

module Python

{

mod = Module(stmt* body)

| Interactive(stmt* body)

| Expression(expr body)

-- not really an actual node but useful in Jython's typesystem.

| Suite(stmt* body)

stmt = FunctionDef(identifier name, arguments args,

stmt* body, expr* decorator_list, expr? returns)

| AsyncFunctionDef(identifier name, arguments args,

stmt* body, expr* decorator_list, expr? returns)

| ClassDef(identifier name,

expr* bases,

keyword* keywords,

stmt* body,

expr* decorator_list)

| Return(expr? value)

| Delete(expr* targets)

| Assign(expr* targets, expr value)

| AugAssign(expr target, operator op, expr value)

-- 'simple' indicates that we annotate simple name without parens

| AnnAssign(expr target, expr annotation, expr? value, int simple)

-- use 'orelse' because else is a keyword in target languages

| For(expr target, expr iter, stmt* body, stmt* orelse)

| AsyncFor(expr target, expr iter, stmt* body, stmt* orelse)

| While(expr test, stmt* body, stmt* orelse)

| If(expr test, stmt* body, stmt* orelse)

| With(withitem* items, stmt* body)

| AsyncWith(withitem* items, stmt* body)

| Raise(expr? exc, expr? cause)

| Try(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)

| Assert(expr test, expr? msg)

| Import(alias* names)

| ImportFrom(identifier? module, alias* names, int? level)

| Global(identifier* names)

| Nonlocal(identifier* names)

| Expr(expr value)

| Pass | Break | Continue

-- XXX Jython will be different

-- col_offset is the byte offset in the utf8 string the parser uses

attributes (int lineno, int col_offset)

-- BoolOp() can use left & right?

expr = BoolOp(boolop op, expr* values)

| BinOp(expr left, operator op, expr right)

| UnaryOp(unaryop op, expr operand)

| Lambda(arguments args, expr body)

| IfExp(expr test, expr body, expr orelse)

| Dict(expr* keys, expr* values)

| Set(expr* elts)

| ListComp(expr elt, comprehension* generators)

| SetComp(expr elt, comprehension* generators)

| DictComp(expr key, expr value, comprehension* generators)

| GeneratorExp(expr elt, comprehension* generators)

-- the grammar constrains where yield expressions can occur

| Await(expr value)

| Yield(expr? value)

| YieldFrom(expr value)

-- need sequences for compare to distinguish between

-- x < 4 < 3 and (x < 4) < 3

| Compare(expr left, cmpop* ops, expr* comparators)

| Call(expr func, expr* args, keyword* keywords)

| Num(object n) -- a number as a PyObject.

| Str(string s) -- need to specify raw, unicode, etc?

| FormattedValue(expr value, int? conversion, expr? format_spec)

| JoinedStr(expr* values)

| Bytes(bytes s)

| NameConstant(singleton value)

| Ellipsis

| Constant(constant value)

-- the following expression can appear in assignment context

| Attribute(expr value, identifier attr, expr_context ctx)

| Subscript(expr value, slice slice, expr_context ctx)

| Starred(expr value, expr_context ctx)

| Name(identifier id, expr_context ctx)

| List(expr* elts, expr_context ctx)

| Tuple(expr* elts, expr_context ctx)

-- col_offset is the byte offset in the utf8 string the parser uses

attributes (int lineno, int col_offset)

slice = Slice(expr? lower, expr? upper, expr? step)

| ExtSlice(slice* dims)

| Index(expr value)

boolop = And | Or

operator = Add | Sub | Mult | MatMult | Div | Mod | Pow | LShift

unaryop = Invert | Not | UAdd | USub

cmpop = Eq | NotEq | Lt | LtE | Gt | GtE | Is | IsNot | In | NotIn

comprehension = (expr target, expr iter, expr* ifs, int is_async)

excepthandler = ExceptHandler(expr? type, identifier? name, stmt* body)

attributes (int lineno, int col_offset)

arguments = (arg* args, arg? vararg, arg* kwonlyargs, expr* kw_defaults,

arg? kwarg, expr* defaults)

arg = (identifier arg, expr? annotation)

attributes (int lineno, int col_offset)

-- keyword arguments supplied to call (NULL identifier for **kwargs)

keyword = (identifier? arg, expr value)

-- import name with optional 'as' alias.

alias = (identifier name, identifier? asname)

withitem = (expr context_expr, expr? optional_vars)

}

</pre></div>

</div>

<h2>33.2.3. <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> Helpers<a class="headerlink" href="#ast-helpers" title="本標題的永久連結">¶</a></h2>

Apart from the node classes, the <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> module defines these utility functions

and classes for traversing abstract syntax trees:

<code class="descclassname">ast.</code><code class="descname">parse</code>(source, filename='<unknown>', mode='exec')<a class="headerlink" href="#ast.parse" title="本定義的永久連結">¶</a></dt>

<dd>Parse the source into an AST node. Equivalent to <code class="docutils literal notranslate">compile(source,

filename, mode, ast.PyCF_ONLY_AST)</code>.

警告

It is possible to crash the Python interpreter with a

sufficiently large/complex string due to stack depth limitations

in Python’s AST compiler.

</div>

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">literal_eval</code>(node_or_string)<a class="headerlink" href="#ast.literal_eval" title="本定義的永久連結">¶</a></dt>

<dd>Safely evaluate an expression node or a string containing a Python literal or

container display. The string or node provided may only consist of the

following Python literal structures: strings, bytes, numbers, tuples, lists,

dicts, sets, booleans, and <code class="docutils literal notranslate">None</code>.

This can be used for safely evaluating strings containing Python values from

untrusted sources without the need to parse the values oneself. It is not

capable of evaluating arbitrarily complex expressions, for example involving

operators or indexing.

警告

It is possible to crash the Python interpreter with a

sufficiently large/complex string due to stack depth limitations

in Python’s AST compiler.

</div>

3.2 版更變: Now allows bytes and set literals.

</div>

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">get_docstring</code>(node, clean=True)<a class="headerlink" href="#ast.get_docstring" title="本定義的永久連結">¶</a></dt>

<dd>Return the docstring of the given node (which must be a

<code class="xref py py-class docutils literal notranslate">FunctionDef</code>, <code class="xref py py-class docutils literal notranslate">AsyncFunctionDef</code>, <code class="xref py py-class docutils literal notranslate">ClassDef</code>,

or <code class="xref py py-class docutils literal notranslate">Module</code> node), or <code class="docutils literal notranslate">None</code> if it has no docstring.

If clean is true, clean up the docstring’s indentation with

<a class="reference internal" href="inspect.html#inspect.cleandoc" title="inspect.cleandoc"><code class="xref py py-func docutils literal notranslate">inspect.cleandoc()</code></a>.

3.5 版更變: <code class="xref py py-class docutils literal notranslate">AsyncFunctionDef</code> is now supported.

</div>

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">fix_missing_locations</code>(node)<a class="headerlink" href="#ast.fix_missing_locations" title="本定義的永久連結">¶</a></dt>

<dd>When you compile a node tree with <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>, the compiler expects

<code class="xref py py-attr docutils literal notranslate">lineno</code> and <code class="xref py py-attr docutils literal notranslate">col_offset</code> attributes for every node that supports

them. This is rather tedious to fill in for generated nodes, so this helper

adds these attributes recursively where not already set, by setting them to

the values of the parent node. It works recursively starting at node.

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">increment_lineno</code>(node, n=1)<a class="headerlink" href="#ast.increment_lineno" title="本定義的永久連結">¶</a></dt>

<dd>Increment the line number of each node in the tree starting at node by n.

This is useful to 「move code」 to a different location in a file.

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">copy_location</code>(new_node, old_node)<a class="headerlink" href="#ast.copy_location" title="本定義的永久連結">¶</a></dt>

<dd>Copy source location (<code class="xref py py-attr docutils literal notranslate">lineno</code> and <code class="xref py py-attr docutils literal notranslate">col_offset</code>) from old_node

to new_node if possible, and return new_node.

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">iter_fields</code>(node)<a class="headerlink" href="#ast.iter_fields" title="本定義的永久連結">¶</a></dt>

<dd>Yield a tuple of <code class="docutils literal notranslate">(fieldname, value)</code> for each field in <code class="docutils literal notranslate">node._fields</code>

that is present on node.

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">iter_child_nodes</code>(node)<a class="headerlink" href="#ast.iter_child_nodes" title="本定義的永久連結">¶</a></dt>

<dd>Yield all direct child nodes of node, that is, all fields that are nodes

and all items of fields that are lists of nodes.

</dd></dl>

<dd>Recursively yield all descendant nodes in the tree starting at node

(including node itself), in no specified order. This is useful if you only

want to modify nodes in place and don’t care about the context.

</dd></dl>

class <code class="descclassname">ast.</code><code class="descname">NodeVisitor</code><a class="headerlink" href="#ast.NodeVisitor" title="本定義的永久連結">¶</a></dt>

<dd>A node visitor base class that walks the abstract syntax tree and calls a

visitor function for every node found. This function may return a value

which is forwarded by the <a class="reference internal" href="#ast.NodeVisitor.visit" title="ast.NodeVisitor.visit"><code class="xref py py-meth docutils literal notranslate">visit()</code></a> method.

This class is meant to be subclassed, with the subclass adding visitor

methods.

<code class="descname">visit</code>(node)<a class="headerlink" href="#ast.NodeVisitor.visit" title="本定義的永久連結">¶</a></dt>

<dd>Visit a node. The default implementation calls the method called

<code class="samp docutils literal notranslate">self.visit_classname</code> where classname is the name of the node

class, or <a class="reference internal" href="#ast.NodeVisitor.generic_visit" title="ast.NodeVisitor.generic_visit"><code class="xref py py-meth docutils literal notranslate">generic_visit()</code></a> if that method doesn’t exist.

</dd></dl>

<code class="descname">generic_visit</code>(node)<a class="headerlink" href="#ast.NodeVisitor.generic_visit" title="本定義的永久連結">¶</a></dt>

<dd>This visitor calls <a class="reference internal" href="#ast.NodeVisitor.visit" title="ast.NodeVisitor.visit"><code class="xref py py-meth docutils literal notranslate">visit()</code></a> on all children of the node.

Note that child nodes of nodes that have a custom visitor method won’t be

visited unless the visitor calls <a class="reference internal" href="#ast.NodeVisitor.generic_visit" title="ast.NodeVisitor.generic_visit"><code class="xref py py-meth docutils literal notranslate">generic_visit()</code></a> or visits them

itself.

</dd></dl>

Don’t use the <a class="reference internal" href="#ast.NodeVisitor" title="ast.NodeVisitor"><code class="xref py py-class docutils literal notranslate">NodeVisitor</code></a> if you want to apply changes to nodes

during traversal. For this a special visitor exists

(<a class="reference internal" href="#ast.NodeTransformer" title="ast.NodeTransformer"><code class="xref py py-class docutils literal notranslate">NodeTransformer</code></a>) that allows modifications.

</dd></dl>

class <code class="descclassname">ast.</code><code class="descname">NodeTransformer</code><a class="headerlink" href="#ast.NodeTransformer" title="本定義的永久連結">¶</a></dt>

<dd>A <a class="reference internal" href="#ast.NodeVisitor" title="ast.NodeVisitor"><code class="xref py py-class docutils literal notranslate">NodeVisitor</code></a> subclass that walks the abstract syntax tree and

allows modification of nodes.

The <a class="reference internal" href="#ast.NodeTransformer" title="ast.NodeTransformer"><code class="xref py py-class docutils literal notranslate">NodeTransformer</code></a> will walk the AST and use the return value of

the visitor methods to replace or remove the old node. If the return value

of the visitor method is <code class="docutils literal notranslate">None</code>, the node will be removed from its

location, otherwise it is replaced with the return value. The return value

may be the original node in which case no replacement takes place.

Here is an example transformer that rewrites all occurrences of name lookups

(<code class="docutils literal notranslate">foo</code>) to <code class="docutils literal notranslate">data['foo']</code>:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>class RewriteName(NodeTransformer):

def visit_Name(self, node):

return copy_location(Subscript(

value=Name(id='data', ctx=Load()),

slice=Index(value=Str(s=node.id)),

ctx=node.ctx

), node)

</pre></div>

</div>

Keep in mind that if the node you’re operating on has child nodes you must

either transform the child nodes yourself or call the <code class="xref py py-meth docutils literal notranslate">generic_visit()</code>

method for the node first.

For nodes that were part of a collection of statements (that applies to all

statement nodes), the visitor may also return a list of nodes rather than

just a single node.

Usually you use the transformer like this:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>node = YourTransformer().visit(node)

</pre></div>

</div>

</dd></dl>

<code class="descclassname">ast.</code><code class="descname">dump</code>(node, annotate_fields=True, include_attributes=False)<a class="headerlink" href="#ast.dump" title="本定義的永久連結">¶</a></dt>

<dd>Return a formatted dump of the tree in node. This is mainly useful for

debugging purposes. The returned string will show the names and the values

for fields. This makes the code impossible to evaluate, so if evaluation is

wanted annotate_fields must be set to <code class="docutils literal notranslate">False</code>. Attributes such as line

numbers and column offsets are not dumped by default. If this is wanted,

include_attributes can be set to <code class="docutils literal notranslate">True</code>.

</dd></dl>

也參考

<a class="reference external" href="https://greentreesnakes.readthedocs.io/">Green Tree Snakes</a>, an external documentation resource, has good

details on working with Python ASTs.

</div>

<ul>

<li><a class="reference internal" href="#">33.2. <code class="docutils literal notranslate">ast</code> — Abstract Syntax Trees</a><ul>

<li><a class="reference internal" href="#node-classes">33.2.1. Node classes</a></li>

<li><a class="reference internal" href="#abstract-grammar">33.2.2. Abstract Grammar</a></li>

<li><a class="reference internal" href="#ast-helpers">33.2.3. <code class="docutils literal notranslate">ast</code> Helpers</a></li>

</ul>

</li>

</ul>

<a href="parser.html"

title="上一章">33.1. <code class="docutils literal notranslate">parser</code> — Access Python parse trees</a>

<a href="symtable.html"

title="下一章">33.3. <code class="docutils literal notranslate">symtable</code> — Access to the compiler’s symbol tables</a>

<li><a href="../bugs.html">Report a Bug</a></li>

<li>

<a href="https://github.com/python/cpython/blob/3.7/Doc/library/ast.rst"

rel="nofollow">Show Source

</a>

</li>

</ul>

</div>

</div>

<ul>

<a href="../genindex.html" title="General Index"

>索引</a></li>

<a href="../py-modindex.html" title="Python 模組索引"

>模組</a> |</li>

<a href="symtable.html" title="33.3. symtable — Access to the compiler’s symbol tables"

>下一頁</a> |</li>

<a href="parser.html" title="33.1. parser — Access Python parse trees"

>上一頁</a> |</li>

<li><img src="../_static/py.png" alt=""

style="vertical-align: middle; margin-top: -1px"/></li>

<li><a href="https://www.python.org/">Python</a> »</li>

<li>

zh_TW

3.7.0

<a href="../index.html">Documentation </a> »

</li>

<li class="nav-item nav-item-1"><a href="index.html" >Python 標準函式庫 (Standard Library)</a> »</li>

<li class="nav-item nav-item-2"><a href="language.html" >33. Python Language Services</a> »</li>

</form>

</div>

</li>

</ul>

</div>

The Python Software Foundation is a non-profit corporation.

<a href="https://www.python.org/psf/donations/">Please donate.</a>

Last updated on 8月 22, 2018.

<a href="../bugs.html">Found a bug</a>?

Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.7.

</div>

</body>

</html>

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

FilesExpand file tree

ast.html

Latest commit

History

ast.html

File metadata and controls