osh/cmd_parse.py

OILS / osh / cmd_parse.py View on Github | oilshell.org

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1	# Copyright 2016 Andy Chu. All rights reserved.
2	# Licensed under the Apache License, Version 2.0 (the "License");
3	# you may not use this file except in compliance with the License.
4	# You may obtain a copy of the License at
5	#
6	# http://www.apache.org/licenses/LICENSE-2.0
7	"""
8	cmd_parse.py - Parse high level shell commands.
9	"""
10	from __future__ import print_function
11
12	from _devbuild.gen import grammar_nt
13	from _devbuild.gen.id_kind_asdl import Id, Id_t, Id_str, Kind, Kind_str
14	from _devbuild.gen.types_asdl import lex_mode_e, cmd_mode_e, cmd_mode_t
15	from _devbuild.gen.syntax_asdl import (
16	loc,
17	SourceLine,
18	source,
19	parse_result,
20	parse_result_t,
21	command,
22	command_t,
23	condition,
24	condition_t,
25	for_iter,
26	ArgList,
27	BraceGroup,
28	LiteralBlock,
29	CaseArm,
30	case_arg,
31	IfArm,
32	pat,
33	pat_t,
34	Redir,
35	redir_param,
36	redir_loc,
37	redir_loc_t,
38	word_e,
39	word_t,
40	CompoundWord,
41	Token,
42	word_part_e,
43	word_part_t,
44	rhs_word,
45	rhs_word_t,
46	sh_lhs,
47	sh_lhs_t,
48	AssignPair,
49	EnvPair,
50	ParsedAssignment,
51	assign_op_e,
52	NameType,
53	proc_sig,
54	proc_sig_e,
55	Proc,
56	Func,
57	)
58	from core import alloc
59	from core import error
60	from core.error import p_die
61	from core import ui
62	from frontend import consts
63	from frontend import lexer
64	from frontend import location
65	from frontend import match
66	from frontend import reader
67	from mycpp.mylib import log
68	from osh import braces
69	from osh import bool_parse
70	from osh import word_
71
72	from typing import Optional, List, Dict, Any, Tuple, cast, TYPE_CHECKING
73	if TYPE_CHECKING:
74	from core.alloc import Arena
75	from core import optview
76	from frontend.lexer import Lexer
77	from frontend.parse_lib import ParseContext, AliasesInFlight
78	from frontend.reader import _Reader
79	from osh.word_parse import WordParser
80
81	_ = Kind_str # for debug prints
82
83	TAB_CH = 9 # ord('\t')
84	SPACE_CH = 32 # ord(' ')
85
86
87	def _ReadHereLines(
88	line_reader, # type: _Reader
89	h, # type: Redir
90	delimiter, # type: str
91	):
92	# type: (...) -> Tuple[List[Tuple[SourceLine, int]], Tuple[SourceLine, int]]
93	# NOTE: We read all lines at once, instead of parsing line-by-line,
94	# because of cases like this:
95	# cat <<EOF
96	# 1 $(echo 2
97	# echo 3) 4
98	# EOF
99	here_lines = [] # type: List[Tuple[SourceLine, int]]
100	last_line = None # type: Tuple[SourceLine, int]
101	strip_leading_tabs = (h.op.id == Id.Redir_DLessDash)
102
103	while True:
104	src_line, unused_offset = line_reader.GetLine()
105
106	if src_line is None: # EOF
107	# An unterminated here doc is just a warning in bash. We make it
108	# fatal because we want to be strict, and because it causes problems
109	# reporting other errors.
110	# Attribute it to the << in <<EOF for now.
111	p_die("Couldn't find terminator for here doc that starts here",
112	h.op)
113
114	assert len(src_line.content) != 0 # None should be the empty line
115
116	line = src_line.content
117
118	# If op is <<-, strip off ALL leading tabs -- not spaces, and not just
119	# the first tab.
120	start_offset = 0
121	if strip_leading_tabs:
122	n = len(line)
123	i = 0 # used after loop exit
124	while i < n:
125	if line[i] != '\t':
126	break
127	i += 1
128	start_offset = i
129
130	if line[start_offset:].rstrip() == delimiter:
131	last_line = (src_line, start_offset)
132	break
133
134	here_lines.append((src_line, start_offset))
135
136	return here_lines, last_line
137
138
139	def _MakeLiteralHereLines(
140	here_lines, # type: List[Tuple[SourceLine, int]]
141	arena, # type: Arena
142	do_lossless, # type: bool
143	):
144	# type: (...) -> List[word_part_t]
145	"""Create a Token for each line.
146
147	For <<'EOF' and <<-'EOF' - single quoted rule
148
149	<<- has non-zero start_offset
150	"""
151	# less precise type, because List[T] is an invariant type
152	tokens = [] # type: List[word_part_t]
153	for src_line, start_offset in here_lines:
154
155	# Maintain lossless invariant for STRIPPED tabs: add a Token to the
156	# arena invariant, but don't refer to it.
157	#
158	# Note: We could use Lit_CharsWithoutPrefix for 'single quoted' EOF
159	# here docs, but it's more complex with double quoted EOF docs.
160
161	if do_lossless: # avoid garbage, doesn't affect correctness
162	arena.NewToken(Id.Lit_CharsWithoutPrefix, start_offset, 0,
163	src_line)
164
165	t = arena.NewToken(Id.Lit_Chars, start_offset, len(src_line.content),
166	src_line)
167	tokens.append(t)
168	return tokens
169
170
171	def _ParseHereDocBody(parse_ctx, r, line_reader, arena):
172	# type: (ParseContext, Redir, _Reader, Arena) -> None
173	"""Fill in attributes of a pending here doc node."""
174	h = cast(redir_param.HereDoc, r.arg)
175	# "If any character in word is quoted, the delimiter shall be formed by
176	# performing quote removal on word, and the here-document lines shall not
177	# be expanded. Otherwise, the delimiter shall be the word itself."
178	# NOTE: \EOF counts, or even E\OF
179	ok, delimiter, delim_quoted = word_.StaticEval(h.here_begin)
180	if not ok:
181	p_die('Invalid here doc delimiter', loc.Word(h.here_begin))
182
183	here_lines, last_line = _ReadHereLines(line_reader, r, delimiter)
184
185	if delim_quoted:
186	# <<'EOF' and <<-'EOF' - Literal for each line.
187	h.stdin_parts = _MakeLiteralHereLines(here_lines, arena,
188	parse_ctx.do_lossless)
189	else:
190	# <<EOF and <<-EOF - Parse as word
191	line_reader = reader.VirtualLineReader(arena, here_lines,
192	parse_ctx.do_lossless)
193	w_parser = parse_ctx.MakeWordParserForHereDoc(line_reader)
194	w_parser.ReadHereDocBody(h.stdin_parts) # fills this in
195
196	end_line, start_offset = last_line
197
198	# Maintain lossless invariant for STRIPPED tabs: add a Token to the
199	# arena invariant, but don't refer to it.
200	if parse_ctx.do_lossless: # avoid garbage, doesn't affect correctness
201	arena.NewToken(Id.Lit_CharsWithoutPrefix, start_offset, 0, end_line)
202
203	# Create a Token with the end terminator. Maintains the invariant that the
204	# tokens "add up".
205	h.here_end_tok = arena.NewToken(Id.Undefined_Tok, start_offset,
206	len(end_line.content), end_line)
207
208
209	def _MakeAssignPair(parse_ctx, preparsed, arena):
210	# type: (ParseContext, ParsedAssignment, Arena) -> AssignPair
211	"""Create an AssignPair from a 4-tuples from DetectShAssignment."""
212
213	left_token = preparsed.left
214	close_token = preparsed.close
215
216	lhs = None # type: sh_lhs_t
217
218	if left_token.id == Id.Lit_VarLike: # s=1
219	if lexer.IsPlusEquals(left_token):
220	var_name = lexer.TokenSliceRight(left_token, -2)
221	op = assign_op_e.PlusEqual
222	else:
223	var_name = lexer.TokenSliceRight(left_token, -1)
224	op = assign_op_e.Equal
225
226	lhs = sh_lhs.Name(left_token, var_name)
227
228	elif left_token.id == Id.Lit_ArrayLhsOpen and parse_ctx.do_lossless:
229	var_name = lexer.TokenSliceRight(left_token, -1)
230	if lexer.IsPlusEquals(close_token):
231	op = assign_op_e.PlusEqual
232	else:
233	op = assign_op_e.Equal
234
235	assert left_token.line == close_token.line, \
236	'%s and %s not on same line' % (left_token, close_token)
237
238	left_pos = left_token.col + left_token.length
239	index_str = left_token.line.content[left_pos:close_token.col]
240	lhs = sh_lhs.UnparsedIndex(left_token, var_name, index_str)
241
242	elif left_token.id == Id.Lit_ArrayLhsOpen: # a[x++]=1
243	var_name = lexer.TokenSliceRight(left_token, -1)
244	if lexer.IsPlusEquals(close_token):
245	op = assign_op_e.PlusEqual
246	else:
247	op = assign_op_e.Equal
248
249	# Similar to SnipCodeString / SnipCodeBlock
250	if left_token.line == close_token.line:
251	# extract what's between brackets
252	s = left_token.col + left_token.length
253	code_str = left_token.line.content[s:close_token.col]
254	else:
255	raise NotImplementedError('%s != %s' %
256	(left_token.line, close_token.line))
257	a_parser = parse_ctx.MakeArithParser(code_str)
258
259	# a[i+1]= is a LHS
260	src = source.Reparsed('array LHS', left_token, close_token)
261	with alloc.ctx_SourceCode(arena, src):
262	index_node = a_parser.Parse() # may raise error.Parse
263
264	lhs = sh_lhs.IndexedName(left_token, var_name, index_node)
265
266	else:
267	raise AssertionError()
268
269	# TODO: Should we also create a rhs_expr.ArrayLiteral here?
270	parts = preparsed.w.parts
271	offset = preparsed.part_offset
272
273	n = len(parts)
274	if offset == n:
275	rhs = rhs_word.Empty # type: rhs_word_t
276	else:
277	w = CompoundWord(parts[offset:])
278	word_.TildeDetectAssign(w)
279	rhs = w
280
281	return AssignPair(left_token, lhs, op, rhs)
282
283
284	def _AppendMoreEnv(preparsed_list, more_env):
285	# type: (List[ParsedAssignment], List[EnvPair]) -> None
286	"""Helper to modify a SimpleCommand node.
287
288	Args:
289	preparsed: a list of 4-tuples from DetectShAssignment
290	more_env: a list to append env_pairs to
291	"""
292	for preparsed in preparsed_list:
293	left_token = preparsed.left
294
295	if left_token.id != Id.Lit_VarLike: # can't be a[x]=1
296	p_die(
297	"Environment binding shouldn't look like an array assignment",
298	left_token)
299
300	if lexer.IsPlusEquals(left_token):
301	p_die('Expected = in environment binding, got +=', left_token)
302
303	var_name = lexer.TokenSliceRight(left_token, -1)
304
305	parts = preparsed.w.parts
306	n = len(parts)
307	offset = preparsed.part_offset
308	if offset == n:
309	rhs = rhs_word.Empty # type: rhs_word_t
310	else:
311	w = CompoundWord(parts[offset:])
312	word_.TildeDetectAssign(w)
313	rhs = w
314
315	more_env.append(EnvPair(left_token, var_name, rhs))
316
317
318	def _SplitSimpleCommandPrefix(words):
319	# type: (List[CompoundWord]) -> Tuple[List[ParsedAssignment], List[CompoundWord]]
320	"""Second pass of SimpleCommand parsing: look for assignment words."""
321	preparsed_list = [] # type: List[ParsedAssignment]
322	suffix_words = [] # type: List[CompoundWord]
323
324	done_prefix = False
325	for w in words:
326	if done_prefix:
327	suffix_words.append(w)
328	continue
329
330	left_token, close_token, part_offset = word_.DetectShAssignment(w)
331	if left_token:
332	preparsed_list.append(
333	ParsedAssignment(left_token, close_token, part_offset, w))
334	else:
335	done_prefix = True
336	suffix_words.append(w)
337
338	return preparsed_list, suffix_words
339
340
341	def _MakeSimpleCommand(
342	preparsed_list, # type: List[ParsedAssignment]
343	suffix_words, # type: List[CompoundWord]
344	typed_args, # type: Optional[ArgList]
345	block, # type: Optional[LiteralBlock]
346	):
347	# type: (...) -> command.Simple
348	"""Create a command.Simple"""
349
350	# FOO=(1 2 3) ls is not allowed.
351	for preparsed in preparsed_list:
352	if word_.HasArrayPart(preparsed.w):
353	p_die("Environment bindings can't contain array literals",
354	loc.Word(preparsed.w))
355
356	# NOTE: It would be possible to add this check back. But it already happens
357	# at runtime in EvalWordSequence2.
358	# echo FOO=(1 2 3) is not allowed (but we should NOT fail on echo FOO[x]=1).
359	if 0:
360	for w in suffix_words:
361	if word_.HasArrayPart(w):
362	p_die("Commands can't contain array literals", loc.Word(w))
363
364	assert len(suffix_words) != 0
365	# {a,b,c} # Use { before brace detection
366	# ~/bin/ls # Use ~ before tilde detection
367	part0 = suffix_words[0].parts[0]
368	blame_tok = location.LeftTokenForWordPart(part0)
369
370	# NOTE: We only do brace DETECTION here, not brace EXPANSION. Therefore we
371	# can't implement bash's behavior of having say {~bob,~jane}/src work,
372	# because we only have a BracedTree.
373	# This is documented in spec/brace-expansion.
374	# NOTE: Technically we could do expansion outside of 'oshc translate', but it
375	# doesn't seem worth it.
376	words2 = braces.BraceDetectAll(suffix_words)
377	words3 = word_.TildeDetectAll(words2)
378
379	more_env = [] # type: List[EnvPair]
380	_AppendMoreEnv(preparsed_list, more_env)
381
382	# do_fork by default
383	return command.Simple(blame_tok, more_env, words3, typed_args, block, True)
384
385
386	class VarChecker(object):
387	"""Statically check for proc and variable usage errors."""
388
389	def __init__(self):
390	# type: () -> None
391	"""
392	Args:
393	oil_proc: Whether to disallow nested proc/function declarations
394	"""
395	# self.tokens for location info: 'proc' or another token
396	self.tokens = [] # type: List[Token]
397	self.names = [] # type: List[Dict[str, Id_t]]
398
399	def Push(self, blame_tok):
400	# type: (Token) -> None
401	"""Called when we enter a shell function, proc, or func.
402
403	Bash allows this, but it's confusing because it's the same as two
404	functions at the top level.
405
406	f() {
407	g() {
408	echo 'top level function defined in another one'
409	}
410	}
411
412	YSH disallows nested procs and funcs.
413	"""
414	if len(self.tokens) != 0:
415	if blame_tok.id == Id.KW_Proc:
416	p_die("procs must be defined at the top level", blame_tok)
417	if blame_tok.id == Id.KW_Func:
418	p_die("funcs must be defined at the top level", blame_tok)
419	if self.tokens[0].id in (Id.KW_Proc, Id.KW_Func):
420	p_die("shell functions can't be defined inside proc or func",
421	blame_tok)
422
423	self.tokens.append(blame_tok)
424	entry = {} # type: Dict[str, Id_t]
425	self.names.append(entry)
426
427	def Pop(self):
428	# type: () -> None
429	self.names.pop()
430	self.tokens.pop()
431
432	def Check(self, keyword_id, var_name, blame_tok):
433	# type: (Id_t, str, Token) -> None
434	"""Check for declaration / mutation errors in proc and func.
435
436	var x
437	x already declared
438	setvar x:
439	x is not declared
440	setglobal x:
441	No errors are possible; we would need all these many conditions to
442	statically know the names:
443	- no 'source'
444	- shopt -u copy_env.
445	- AND use lib has to be static
446
447	What about bare assignment in Hay? I think these are dynamic checks --
448	there is no static check. Hay is for building up data imperatively,
449	and then LATER, right before main(), it can be type checked.
450
451	Package {
452	version = '3.11'
453	version = '3.12'
454	}
455	"""
456	# No static checks are the global level! Because of 'source', var and
457	# setvar are essentially the same.
458	if len(self.names) == 0:
459	return
460
461	top = self.names[-1]
462	if keyword_id == Id.KW_Var:
463	if var_name in top:
464	p_die('%r was already declared' % var_name, blame_tok)
465	else:
466	top[var_name] = keyword_id
467
468	if keyword_id == Id.KW_SetVar:
469	if var_name not in top:
470	# Note: the solution could be setglobal, etc.
471	p_die(
472	"setvar couldn't find matching 'var %s' (OILS-ERR-10)" %
473	var_name, blame_tok)
474
475
476	class ctx_VarChecker(object):
477
478	def __init__(self, var_checker, blame_tok):
479	# type: (VarChecker, Token) -> None
480	var_checker.Push(blame_tok)
481	self.var_checker = var_checker
482
483	def __enter__(self):
484	# type: () -> None
485	pass
486
487	def __exit__(self, type, value, traceback):
488	# type: (Any, Any, Any) -> None
489	self.var_checker.Pop()
490
491
492	class ctx_CmdMode(object):
493
494	def __init__(self, cmd_parse, new_cmd_mode):
495	# type: (CommandParser, cmd_mode_t) -> None
496	self.cmd_parse = cmd_parse
497	self.prev_cmd_mode = cmd_parse.cmd_mode
498	cmd_parse.cmd_mode = new_cmd_mode
499
500	def __enter__(self):
501	# type: () -> None
502	pass
503
504	def __exit__(self, type, value, traceback):
505	# type: (Any, Any, Any) -> None
506	self.cmd_parse.cmd_mode = self.prev_cmd_mode
507
508
509	SECONDARY_KEYWORDS = [
510	Id.KW_Do, Id.KW_Done, Id.KW_Then, Id.KW_Fi, Id.KW_Elif, Id.KW_Else,
511	Id.KW_Esac
512	]
513
514
515	class CommandParser(object):
516	"""Recursive descent parser derived from POSIX shell grammar.
517
518	This is a BNF grammar:
519	https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_10
520
521	- Augmented with both bash/OSH and YSH constructs.
522
523	- We use regex-like iteration rather than recursive references
524	? means optional (0 or 1)
525	* means 0 or more
526	+ means 1 or more
527
528	- Keywords are spelled in Caps:
529	If Elif Case
530
531	- Operator tokens are quoted:
532	'(' '\|'
533
534	or can be spelled directly if it matters:
535
536	Op_LParen Op_Pipe
537
538	- Non-terminals are snake_case:
539	brace_group subshell
540
541	Methods in this class should ROUGHLY CORRESPOND to grammar productions, and
542	the production should be in the method docstrings, e.g.
543
544	def ParseSubshell():
545	"
546	subshell : '(' compound_list ')'
547
548	Looking at Op_LParen # Comment to say how this method is called
549	"
550
551	The grammar may be factored to make parsing easier.
552	"""
553
554	def __init__(self,
555	parse_ctx,
556	parse_opts,
557	w_parser,
558	lexer,
559	line_reader,
560	eof_id=Id.Eof_Real):
561	# type: (ParseContext, optview.Parse, WordParser, Lexer, _Reader, Id_t) -> None
562	self.parse_ctx = parse_ctx
563	self.aliases = parse_ctx.aliases # aliases to expand at parse time
564
565	self.parse_opts = parse_opts
566	self.w_parser = w_parser # type: WordParser # for normal parsing
567	self.lexer = lexer # for pushing hints, lookahead to (
568	self.line_reader = line_reader # for here docs
569	self.eof_id = eof_id
570
571	self.arena = line_reader.arena # for adding here doc and alias spans
572	self.aliases_in_flight = [] # type: AliasesInFlight
573
574	# A hacky boolean to remove 'if cd / {' ambiguity.
575	self.allow_block = True
576
577	# Stack of booleans for nested Attr and SHELL nodes.
578	# Attr nodes allow bare assignment x = 42, but not shell x=42.
579	# SHELL nodes are the inverse. 'var x = 42' is preferred in shell
580	# nodes, but x42 is still allowed.
581	#
582	# Note: this stack could be optimized by turning it into an integer and
583	# binary encoding.
584	self.hay_attrs_stack = [] # type: List[bool]
585
586	# Note: VarChecker is instantiated with each CommandParser, which means
587	# that two 'proc foo' -- inside a command sub and outside -- don't
588	# conflict, because they use different CommandParser instances. I think
589	# this OK but you can imagine different behaviors.
590	self.var_checker = VarChecker()
591
592	self.cmd_mode = cmd_mode_e.Shell # type: cmd_mode_t
593
594	self.Reset()
595
596	# Init_() function for "keyword arg"
597	def Init_AliasesInFlight(self, aliases_in_flight):
598	# type: (AliasesInFlight) -> None
599	self.aliases_in_flight = aliases_in_flight
600
601	def Reset(self):
602	# type: () -> None
603	"""Reset our own internal state.
604
605	Called by the interactive loop.
606	"""
607	# Cursor state set by _GetWord()
608	self.next_lex_mode = lex_mode_e.ShCommand
609	self.cur_word = None # type: word_t # current word
610	self.c_kind = Kind.Undefined
611	self.c_id = Id.Undefined_Tok
612
613	self.pending_here_docs = [] # type: List[Redir]
614
615	def ResetInputObjects(self):
616	# type: () -> None
617	"""Reset the internal state of our inputs.
618
619	Called by the interactive loop.
620	"""
621	self.w_parser.Reset()
622	self.lexer.ResetInputObjects()
623	self.line_reader.Reset()
624
625	def _SetNext(self):
626	# type: () -> None
627	"""Call this when you no longer need the current token.
628
629	This method is lazy. A subsequent call to _GetWord() will
630	actually read the next Token.
631	"""
632	self.next_lex_mode = lex_mode_e.ShCommand
633
634	def _SetNextBrack(self):
635	# type: () -> None
636	self.next_lex_mode = lex_mode_e.ShCommandFakeBrack
637
638	def _GetWord(self):
639	# type: () -> None
640	"""Call this when you need to make a decision based on Id or Kind.
641
642	If there was an "unfulfilled" call to _SetNext(), it reads a word and sets
643	self.c_id and self.c_kind.
644
645	Otherwise it does nothing.
646	"""
647	if self.next_lex_mode != lex_mode_e.Undefined:
648	w = self.w_parser.ReadWord(self.next_lex_mode)
649	#log("w %s", w)
650
651	# Here docs only happen in command mode, so other kinds of newlines don't
652	# count.
653	if w.tag() == word_e.Operator:
654	tok = cast(Token, w)
655	if tok.id == Id.Op_Newline:
656	for h in self.pending_here_docs:
657	_ParseHereDocBody(self.parse_ctx, h, self.line_reader,
658	self.arena)
659	del self.pending_here_docs[:] # No .clear() until Python 3.3.
660
661	self.cur_word = w
662
663	self.c_kind = word_.CommandKind(self.cur_word)
664	# Has special case for Id.Lit_{LBrace,RBrace,Equals}
665	self.c_id = word_.CommandId(self.cur_word)
666	self.next_lex_mode = lex_mode_e.Undefined
667
668	def _Eat(self, c_id, msg=None):
669	# type: (Id_t, Optional[str]) -> word_t
670	"""Consume a word of a type, maybe showing a custom error message.
671
672	Args:
673	c_id: the Id we expected
674	msg: improved error message
675	"""
676	self._GetWord()
677	if self.c_id != c_id:
678	if msg is None:
679	msg = 'Expected word type %s, got %s' % (
680	ui.PrettyId(c_id), ui.PrettyId(self.c_id))
681	p_die(msg, loc.Word(self.cur_word))
682
683	skipped = self.cur_word
684	self._SetNext()
685	return skipped
686
687	def _NewlineOk(self):
688	# type: () -> None
689	"""Check for optional newline and consume it."""
690	self._GetWord()
691	if self.c_id == Id.Op_Newline:
692	self._SetNext()
693
694	def _AtSecondaryKeyword(self):
695	# type: () -> bool
696	self._GetWord()
697	if self.c_id in SECONDARY_KEYWORDS:
698	return True
699	return False
700
701	def ParseRedirect(self):
702	# type: () -> Redir
703	self._GetWord()
704	assert self.c_kind == Kind.Redir, self.cur_word
705	op_tok = cast(Token, self.cur_word) # for MyPy
706
707	# Note: the lexer could take distinguish between
708	# >out
709	# 3>out
710	# {fd}>out
711	#
712	# which would make the code below faster. But small string optimization
713	# would also speed it up, since redirects are small.
714
715	# One way to do this is with Kind.Redir and Kind.RedirNamed, and then
716	# possibly "unify" the IDs by subtracting a constant like 8 or 16?
717
718	op_val = lexer.TokenVal(op_tok)
719	if op_val[0] == '{':
720	pos = op_val.find('}')
721	assert pos != -1 # lexer ensures this
722	where = redir_loc.VarName(op_val[1:pos]) # type: redir_loc_t
723
724	elif op_val[0].isdigit():
725	pos = 1
726	if op_val[1].isdigit():
727	pos = 2
728	where = redir_loc.Fd(int(op_val[:pos]))
729
730	else:
731	where = redir_loc.Fd(consts.RedirDefaultFd(op_tok.id))
732
733	self._SetNext()
734
735	self._GetWord()
736	# Other redirect
737	if self.c_kind != Kind.Word:
738	p_die('Invalid token after redirect operator',
739	loc.Word(self.cur_word))
740
741	# Here doc
742	if op_tok.id in (Id.Redir_DLess, Id.Redir_DLessDash):
743	arg = redir_param.HereDoc.CreateNull()
744	arg.here_begin = self.cur_word
745	arg.stdin_parts = []
746
747	r = Redir(op_tok, where, arg)
748
749	self.pending_here_docs.append(r) # will be filled on next newline.
750
751	self._SetNext()
752	return r
753
754	arg_word = self.cur_word
755	tilde = word_.TildeDetect(arg_word)
756	if tilde:
757	arg_word = tilde
758	self._SetNext()
759
760	# We should never get Empty, Token, etc.
761	assert arg_word.tag() == word_e.Compound, arg_word
762	return Redir(op_tok, where, cast(CompoundWord, arg_word))
763
764	def _ParseRedirectList(self):
765	# type: () -> List[Redir]
766	"""Try parsing any redirects at the cursor.
767
768	This is used for blocks only, not commands.
769	"""
770	redirects = [] # type: List[Redir]
771	while True:
772	# This prediction needs to ONLY accept redirect operators. Should we
773	# make them a separate Kind?
774	self._GetWord()
775	if self.c_kind != Kind.Redir:
776	break
777
778	node = self.ParseRedirect()
779	redirects.append(node)
780	self._SetNext()
781
782	return redirects
783
784	def _MaybeParseRedirectList(self, node):
785	# type: (command_t) -> command_t
786	"""Try parsing redirects at the current position.
787
788	If there are any, then wrap the command_t argument with a
789	command.Redirect node. Otherwise, return argument unchanged.
790	"""
791	self._GetWord()
792	if self.c_kind != Kind.Redir:
793	return node
794
795	redirects = [self.ParseRedirect()]
796
797	while True:
798	# This prediction needs to ONLY accept redirect operators. Should we
799	# make them a separate Kind?
800	self._GetWord()
801	if self.c_kind != Kind.Redir:
802	break
803
804	redirects.append(self.ParseRedirect())
805	self._SetNext()
806
807	return command.Redirect(node, redirects)
808
809	def _ScanSimpleCommand(self):
810	# type: () -> Tuple[List[Redir], List[CompoundWord], Optional[ArgList], Optional[LiteralBlock]]
811	"""YSH extends simple commands with typed args and blocks.
812
813	Shell has a recursive grammar, which awkwardly expresses
814	non-grammatical rules:
815
816	simple_command : cmd_prefix cmd_word cmd_suffix
817	\| cmd_prefix cmd_word
818	\| cmd_prefix
819	\| cmd_name cmd_suffix
820	\| cmd_name
821	;
822	cmd_name : WORD /* Apply rule 7a */
823	;
824	cmd_word : WORD /* Apply rule 7b */
825	;
826	cmd_prefix : io_redirect
827	\| cmd_prefix io_redirect
828	\| ASSIGNMENT_WORD
829	\| cmd_prefix ASSIGNMENT_WORD
830	;
831	cmd_suffix : io_redirect
832	\| cmd_suffix io_redirect
833	\| WORD
834	\| cmd_suffix WORD
835
836	YSH grammar:
837
838	redirect = redir_op WORD
839	item = WORD \| redirect
840
841	typed_args =
842	'(' arglist ')'
843	\| '[' arglist ']'
844
845	simple_command =
846	cmd_prefix* item+ typed_args? BraceGroup? cmd_suffix*
847
848	Notably, redirects shouldn't appear after typed args, or after
849	BraceGroup.
850
851	Examples:
852
853	This is an assignment:
854	foo=1 >out
855
856	This is a command.Simple
857	>out
858
859	What about
860	>out (42)
861	"""
862	redirects = [] # type: List[Redir]
863	words = [] # type: List[CompoundWord]
864	typed_args = None # type: Optional[ArgList]
865	block = None # type: Optional[LiteralBlock]
866
867	first_word_caps = False # does first word look like Caps, but not CAPS
868
869	i = 0
870	while True:
871	self._GetWord()
872
873	# If we got { }, change it to something that's not Kind.Word
874	kind2 = self.c_kind
875	if (kind2 == Kind.Word and self.parse_opts.parse_brace() and
876	self.c_id in (Id.Lit_LBrace, Id.Lit_RBrace)):
877	kind2 = Kind.Op
878
879	if kind2 == Kind.Redir:
880	node = self.ParseRedirect()
881	redirects.append(node)
882
883	elif kind2 == Kind.Word:
884	w = cast(CompoundWord, self.cur_word) # Kind.Word ensures this
885
886	if i == 0:
887	# Disallow leading =a because it's confusing
888	part0 = w.parts[0]
889	if part0.tag() == word_part_e.Literal:
890	tok = cast(Token, part0)
891	if tok.id == Id.Lit_Equals:
892	p_die(
893	"=word isn't allowed. Hint: add a space after =, or quote it",
894	tok)
895
896	# Is the first word a Hay Attr word?
897	#
898	# Can we remove this StaticEval() call, and just look
899	# inside Token? I think once we get rid of SHELL nodes,
900	# this will be simpler.
901
902	ok, word_str, quoted = word_.StaticEval(w)
903	# Foo { a = 1 } is OK, but not foo { a = 1 } or FOO { a = 1 }
904	if (ok and len(word_str) and word_str[0].isupper() and
905	not word_str.isupper()):
906	first_word_caps = True
907	#log('W %s', word_str)
908
909	words.append(w)
910
911	else:
912	break
913
914	self._SetNextBrack() # Allow bracket for SECOND word on
915	i += 1
916
917	# my-cmd (x) or my-cmd [x]
918	self._GetWord()
919	if self.c_id == Id.Op_LParen:
920	# 1. Check that there's a preceding space
921	prev_byte = self.lexer.ByteLookBack()
922	if prev_byte not in (SPACE_CH, TAB_CH):
923	if self.parse_opts.parse_at():
924	p_die('Space required before (', loc.Word(self.cur_word))
925	else:
926	# inline func call like @sorted(x) is invalid in OSH, but the
927	# solution isn't a space
928	p_die(
929	'Unexpected left paren (might need a space before it)',
930	loc.Word(self.cur_word))
931
932	# 2. Check that it's not (). We disallow this because it's a no-op and
933	# there could be confusion with shell func defs.
934	# For some reason we need to call lexer.LookPastSpace, not
935	# w_parser.LookPastSpace. I think this is because we're at (, which is
936	# an operator token. All the other cases are like 'x=', which is PART
937	# of a word, and we don't know if it will end.
938	next_id = self.lexer.LookPastSpace(lex_mode_e.ShCommand)
939	if next_id == Id.Op_RParen:
940	p_die('Empty arg list not allowed', loc.Word(self.cur_word))
941
942	typed_args = self.w_parser.ParseProcCallArgs(
943	grammar_nt.ysh_eager_arglist)
944
945	self._SetNext()
946
947	elif self.c_id == Id.Op_LBracket: # only when parse_bracket set
948	typed_args = self.w_parser.ParseProcCallArgs(
949	grammar_nt.ysh_lazy_arglist)
950
951	self._SetNext()
952
953	self._GetWord()
954
955	# Allow redirects after typed args, e.g.
956	# json write (x) > out.txt
957	if self.c_kind == Kind.Redir:
958	redirects.extend(self._ParseRedirectList())
959
960	# my-cmd { echo hi } my-cmd (x) { echo hi } ...
961	if (self.parse_opts.parse_brace() and self.c_id == Id.Lit_LBrace and
962	# Disabled for if/while condition, etc.
963	self.allow_block):
964
965	# allow x = 42
966	self.hay_attrs_stack.append(first_word_caps)
967	brace_group = self.ParseBraceGroup()
968
969	# So we can get the source code back later
970	lines = self.arena.SaveLinesAndDiscard(brace_group.left,
971	brace_group.right)
972	block = LiteralBlock(brace_group, lines)
973
974	self.hay_attrs_stack.pop()
975
976	self._GetWord()
977
978	# Allow redirects after block, e.g.
979	# cd /tmp { echo $PWD } > out.txt
980	if self.c_kind == Kind.Redir:
981	redirects.extend(self._ParseRedirectList())
982
983	return redirects, words, typed_args, block
984
985	def _MaybeExpandAliases(self, words):
986	# type: (List[CompoundWord]) -> Optional[command_t]
987	"""Try to expand aliases.
988
989	Args:
990	words: A list of Compound
991
992	Returns:
993	A new LST node, or None.
994
995	Our implementation of alias has two design choices:
996	- Where to insert it in parsing. We do it at the end of ParseSimpleCommand.
997	- What grammar rule to parse the expanded alias buffer with. In our case
998	it's ParseCommand().
999
1000	This doesn't quite match what other shells do, but I can't figure out a
1001	better places.
1002
1003	Most test cases pass, except for ones like:
1004
1005	alias LBRACE='{'
1006	LBRACE echo one; echo two; }
1007
1008	alias MULTILINE='echo 1
1009	echo 2
1010	echo 3'
1011	MULTILINE
1012
1013	NOTE: dash handles aliases in a totally different way. It has a global
1014	variable checkkwd in parser.c. It assigns it all over the grammar, like
1015	this:
1016
1017	checkkwd = CHKNL \| CHKKWD \| CHKALIAS;
1018
1019	The readtoken() function checks (checkkwd & CHKALIAS) and then calls
1020	lookupalias(). This seems to provide a consistent behavior among shells,
1021	but it's less modular and testable.
1022
1023	Bash also uses a global 'parser_state & PST_ALEXPNEXT'.
1024
1025	Returns:
1026	A command node if any aliases were expanded, or None otherwise.
1027	"""
1028	# Start a new list if there aren't any. This will be passed recursively
1029	# through CommandParser instances.
1030	aliases_in_flight = (self.aliases_in_flight
1031	if len(self.aliases_in_flight) else [])
1032
1033	# for error message
1034	first_word_str = None # type: Optional[str]
1035	argv0_loc = loc.Word(words[0])
1036
1037	expanded = [] # type: List[str]
1038	i = 0
1039	n = len(words)
1040
1041	while i < n:
1042	w = words[i]
1043
1044	ok, word_str, quoted = word_.StaticEval(w)
1045	if not ok or quoted:
1046	break
1047
1048	alias_exp = self.aliases.get(word_str)
1049	if alias_exp is None:
1050	break
1051
1052	# Prevent infinite loops. This is subtle: we want to prevent infinite
1053	# expansion of alias echo='echo x'. But we don't want to prevent
1054	# expansion of the second word in 'echo echo', so we add 'i' to
1055	# "aliases_in_flight".
1056	if (word_str, i) in aliases_in_flight:
1057	break
1058
1059	if i == 0:
1060	first_word_str = word_str # for error message
1061
1062	#log('%r -> %r', word_str, alias_exp)
1063	aliases_in_flight.append((word_str, i))
1064	expanded.append(alias_exp)
1065	i += 1
1066
1067	if not alias_exp.endswith(' '):
1068	# alias e='echo [ ' is the same expansion as
1069	# alias e='echo ['
1070	# The trailing space indicates whether we should continue to expand
1071	# aliases; it's not part of it.
1072	expanded.append(' ')
1073	break # No more expansions
1074
1075	if len(expanded) == 0: # No expansions; caller does parsing.
1076	return None
1077
1078	# We are expanding an alias, so copy the rest of the words and re-parse.
1079	if i < n:
1080	left_tok = location.LeftTokenForWord(words[i])
1081	right_tok = location.RightTokenForWord(words[-1])
1082
1083	# OLD CONSTRAINT
1084	#assert left_tok.line_id == right_tok.line_id
1085
1086	words_str = self.arena.SnipCodeString(left_tok, right_tok)
1087	expanded.append(words_str)
1088
1089	code_str = ''.join(expanded)
1090
1091	# TODO:
1092	# Aliases break static parsing (like backticks), so use our own Arena.
1093	# This matters for Hay, which calls SaveLinesAndDiscard().
1094	# arena = alloc.Arena()
1095	arena = self.arena
1096
1097	line_reader = reader.StringLineReader(code_str, arena)
1098	cp = self.parse_ctx.MakeOshParser(line_reader)
1099	cp.Init_AliasesInFlight(aliases_in_flight)
1100
1101	# break circular dep
1102	from frontend import parse_lib
1103
1104	# The interaction between COMPLETION and ALIASES requires special care.
1105	# See docstring of BeginAliasExpansion() in parse_lib.py.
1106	src = source.Alias(first_word_str, argv0_loc)
1107	with alloc.ctx_SourceCode(arena, src):
1108	with parse_lib.ctx_Alias(self.parse_ctx.trail):
1109	try:
1110	# _ParseCommandTerm() handles multiline commands, compound
1111	# commands, etc. as opposed to ParseLogicalLine()
1112	node = cp._ParseCommandTerm()
1113	except error.Parse as e:
1114	# Failure to parse alias expansion is a fatal error
1115	# We don't need more handling here/
1116	raise
1117
1118	if 0:
1119	log('AFTER expansion:')
1120	node.PrettyPrint()
1121
1122	return node
1123
1124	def ParseSimpleCommand(self):
1125	# type: () -> command_t
1126	"""Fixed transcription of the POSIX grammar
1127
1128	io_file : '<' filename
1129	\| LESSAND filename
1130	...
1131
1132	io_here : DLESS here_end
1133	\| DLESSDASH here_end
1134
1135	redirect : IO_NUMBER (io_redirect \| io_here)
1136
1137	prefix_part : ASSIGNMENT_WORD \| redirect
1138	cmd_part : WORD \| redirect
1139
1140	assign_kw : Declare \| Export \| Local \| Readonly
1141
1142	# Without any words it is parsed as a command, not an assignment
1143	assign_listing : assign_kw
1144
1145	# Now we have something to do (might be changing assignment flags too)
1146	# NOTE: any prefixes should be a warning, but they are allowed in shell.
1147	assignment : prefix_part* assign_kw (WORD \| ASSIGNMENT_WORD)+
1148
1149	# an external command, a function call, or a builtin -- a "word_command"
1150	word_command : prefix_part* cmd_part+
1151
1152	simple_command : assign_listing
1153	\| assignment
1154	\| proc_command
1155
1156	Simple imperative algorithm:
1157
1158	1) Read a list of words and redirects. Append them to separate lists.
1159	2) Look for the first non-assignment word. If it's declare, etc., then
1160	keep parsing words AND assign words. Otherwise, just parse words.
1161	3) If there are no non-assignment words, then it's a global assignment.
1162
1163	{ redirects, global assignments } OR
1164	{ redirects, prefix_bindings, words } OR
1165	{ redirects, ERROR_prefix_bindings, keyword, assignments, words }
1166
1167	THEN CHECK that prefix bindings don't have any array literal parts!
1168	global assignment and keyword assignments can have the of course.
1169	well actually EXPORT shouldn't have them either -- WARNING
1170
1171	3 cases we want to warn: prefix_bindings for assignment, and array literal
1172	in prefix bindings, or export
1173
1174	A command can be an assignment word, word, or redirect on its own.
1175
1176	ls
1177	>out.txt
1178
1179	>out.txt FOO=bar # this touches the file
1180
1181	Or any sequence:
1182	ls foo bar
1183	<in.txt ls foo bar >out.txt
1184	<in.txt ls >out.txt foo bar
1185
1186	Or add one or more environment bindings:
1187	VAR=val env
1188	>out.txt VAR=val env
1189
1190	here_end vs filename is a matter of whether we test that it's quoted. e.g.
1191	<<EOF vs <<'EOF'.
1192	"""
1193	redirects, words, typed_args, block = self._ScanSimpleCommand()
1194
1195	typed_loc = None # type: Optional[Token]
1196	if block:
1197	typed_loc = block.brace_group.left
1198	if typed_args:
1199	typed_loc = typed_args.left # preferred over block location
1200
1201	if len(words) == 0: # e.g. >out.txt # redirect without words
1202	assert len(redirects) != 0
1203	if typed_loc is not None:
1204	p_die("Unexpected typed args", typed_loc)
1205	return command.Redirect(command.NoOp, redirects)
1206
1207	preparsed_list, suffix_words = _SplitSimpleCommandPrefix(words)
1208	if len(preparsed_list):
1209	# Disallow X=Y inside proc and func
1210	# and inside Hay Attr blocks
1211	# But allow X=Y at the top level
1212	# for interactive use foo=bar
1213	# for global constants GLOBAL=~/src
1214	# because YSH assignment doesn't have tilde sub
1215	if len(suffix_words) == 0:
1216	if (self.cmd_mode != cmd_mode_e.Shell or
1217	(len(self.hay_attrs_stack) and self.hay_attrs_stack[-1])):
1218	p_die('Use var/setvar to assign in YSH',
1219	preparsed_list[0].left)
1220
1221	# Set a reference to words and redirects for completion. We want to
1222	# inspect this state after a failed parse.
1223	self.parse_ctx.trail.SetLatestWords(suffix_words, redirects)
1224
1225	if len(suffix_words) == 0:
1226	if typed_loc is not None:
1227	p_die("Unexpected typed args", typed_loc)
1228
1229	# ShAssignment: No suffix words like ONE=1 a[x]=1 TWO=2
1230	pairs = [] # type: List[AssignPair]
1231	for preparsed in preparsed_list:
1232	pairs.append(
1233	_MakeAssignPair(self.parse_ctx, preparsed, self.arena))
1234
1235	left_tok = location.LeftTokenForCompoundWord(words[0])
1236	assign_node = command.ShAssignment(left_tok, pairs)
1237	if len(redirects):
1238	return command.Redirect(assign_node, redirects)
1239	else:
1240	return assign_node
1241
1242	kind, kw_token = word_.IsControlFlow(suffix_words[0])
1243
1244	if kind == Kind.ControlFlow:
1245	if not self.parse_opts.parse_ignored() and len(redirects):
1246	p_die("Control flow shouldn't have redirects", kw_token)
1247	if len(preparsed_list): # FOO=bar local spam=eggs not allowed
1248	p_die("Control flow shouldn't have environment bindings",
1249	preparsed_list[0].left)
1250
1251	if kw_token.id == Id.ControlFlow_Return:
1252	# return x - inside procs and shell functions
1253	# return (x) - inside funcs
1254	if typed_args is None:
1255	if self.cmd_mode not in (cmd_mode_e.Shell,
1256	cmd_mode_e.Proc):
1257	p_die('Shell-style returns not allowed here', kw_token)
1258	else:
1259	if self.cmd_mode != cmd_mode_e.Func:
1260	p_die('Typed return is only allowed inside func',
1261	typed_loc)
1262	if len(typed_args.pos_args) != 1:
1263	p_die("Typed return expects one argument", typed_loc)
1264	if len(typed_args.named_args) != 0:
1265	p_die("Typed return doesn't take named arguments",
1266	typed_loc)
1267	return command.Retval(kw_token, typed_args.pos_args[0])
1268
1269	# Except for return (x), we shouldn't have typed args
1270	if typed_loc is not None:
1271	p_die("Unexpected typed args", typed_loc)
1272
1273	# Attach the token for errors. (ShAssignment may not need it.)
1274	if len(suffix_words) == 1:
1275	arg_word = None # type: Optional[word_t]
1276	elif len(suffix_words) == 2:
1277	arg_word = suffix_words[1]
1278	else:
1279	p_die('Unexpected argument to %r' % lexer.TokenVal(kw_token),
1280	loc.Word(suffix_words[2]))
1281
1282	return command.ControlFlow(kw_token, arg_word)
1283
1284	# Alias expansion only understands words, not typed args ( ) or block { }
1285	if not typed_args and not block and self.parse_opts.expand_aliases():
1286	# If any expansions were detected, then parse again.
1287	expanded_node = self._MaybeExpandAliases(suffix_words)
1288	if expanded_node:
1289	# Attach env bindings and redirects to the expanded node.
1290	more_env = [] # type: List[EnvPair]
1291	_AppendMoreEnv(preparsed_list, more_env)
1292	exp = command.ExpandedAlias(expanded_node, more_env)
1293	if len(redirects):
1294	return command.Redirect(exp, redirects)
1295	else:
1296	return exp
1297
1298	# TODO: check that we don't have env1=x x[1]=y env2=z here.
1299
1300	# FOO=bar printenv.py FOO
1301	node = _MakeSimpleCommand(preparsed_list, suffix_words, typed_args,
1302	block)
1303	if len(redirects):
1304	return command.Redirect(node, redirects)
1305	else:
1306	return node
1307
1308	def ParseBraceGroup(self):
1309	# type: () -> BraceGroup
1310	"""
1311	Original:
1312	brace_group : LBrace command_list RBrace ;
1313
1314	YSH:
1315	brace_group : LBrace (Op_Newline IgnoredComment?)? command_list RBrace ;
1316
1317	The doc comment can only occur if there's a newline.
1318	"""
1319	ate = self._Eat(Id.Lit_LBrace)
1320	left = word_.BraceToken(ate)
1321
1322	doc_word = None # type: word_t
1323	self._GetWord()
1324	if self.c_id == Id.Op_Newline:
1325	self._SetNext()
1326	# Set a flag so we don't skip over ###
1327	with word_.ctx_EmitDocToken(self.w_parser):
1328	self._GetWord()
1329
1330	if self.c_id == Id.Ignored_Comment:
1331	doc_word = self.cur_word
1332	self._SetNext()
1333
1334	# Id.Ignored_Comment means it's a Token, or None
1335	doc_token = cast(Token, doc_word)
1336
1337	c_list = self._ParseCommandList()
1338
1339	ate = self._Eat(Id.Lit_RBrace)
1340	right = word_.BraceToken(ate)
1341
1342	# Note(andychu): Related ASDL bug #1216. Choosing the Python [] behavior
1343	# would allow us to revert this back to None, which was changed in
1344	# https://github.com/oilshell/oil/pull/1211. Choosing the C++ nullptr
1345	# behavior saves allocations, but is less type safe.
1346	return BraceGroup(left, doc_token, c_list.children, right)
1347
1348	def ParseDoGroup(self):
1349	# type: () -> command.DoGroup
1350	"""Used by ForEach, ForExpr, While, Until. Should this be a Do node?
1351
1352	do_group : Do command_list Done ; /* Apply rule 6 */
1353	"""
1354	ate = self._Eat(Id.KW_Do)
1355	do_kw = word_.AsKeywordToken(ate)
1356
1357	c_list = self._ParseCommandList() # could be anything
1358
1359	ate = self._Eat(Id.KW_Done)
1360	done_kw = word_.AsKeywordToken(ate)
1361
1362	return command.DoGroup(do_kw, c_list.children, done_kw)
1363
1364	def ParseForWords(self):
1365	# type: () -> Tuple[List[CompoundWord], Optional[Token]]
1366	"""
1367	for_words : WORD* for_sep
1368	;
1369	for_sep : ';' newline_ok
1370	\| NEWLINES
1371	;
1372	"""
1373	words = [] # type: List[CompoundWord]
1374	# The token of any semi-colon, so we can remove it.
1375	semi_tok = None # type: Optional[Token]
1376
1377	while True:
1378	self._GetWord()
1379	if self.c_id == Id.Op_Semi:
1380	tok = cast(Token, self.cur_word)
1381	semi_tok = tok
1382	self._SetNext()
1383	self._NewlineOk()
1384	break
1385	elif self.c_id == Id.Op_Newline:
1386	self._SetNext()
1387	break
1388	elif self.parse_opts.parse_brace() and self.c_id == Id.Lit_LBrace:
1389	break
1390
1391	if self.cur_word.tag() != word_e.Compound:
1392	# TODO: Can we also show a pointer to the 'for' keyword?
1393	p_die('Invalid word in for loop', loc.Word(self.cur_word))
1394
1395	w2 = cast(CompoundWord, self.cur_word)
1396	words.append(w2)
1397	self._SetNext()
1398	return words, semi_tok
1399
1400	def _ParseForExprLoop(self, for_kw):
1401	# type: (Token) -> command.ForExpr
1402	"""
1403	Shell:
1404	for '((' init ';' cond ';' update '))' for_sep? do_group
1405
1406	YSH:
1407	for '((' init ';' cond ';' update '))' for_sep? brace_group
1408	"""
1409	node = self.w_parser.ReadForExpression()
1410	node.keyword = for_kw
1411
1412	self._SetNext()
1413
1414	self._GetWord()
1415	if self.c_id == Id.Op_Semi:
1416	self._SetNext()
1417	self._NewlineOk()
1418	elif self.c_id == Id.Op_Newline:
1419	self._SetNext()
1420	elif self.c_id == Id.KW_Do: # missing semicolon/newline allowed
1421	pass
1422	elif self.c_id == Id.Lit_LBrace: # does NOT require parse_brace
1423	pass
1424	else:
1425	p_die('Invalid word after for expression', loc.Word(self.cur_word))
1426
1427	if self.c_id == Id.Lit_LBrace:
1428	node.body = self.ParseBraceGroup()
1429	else:
1430	node.body = self.ParseDoGroup()
1431	return node
1432
1433	def _ParseForEachLoop(self, for_kw):
1434	# type: (Token) -> command.ForEach
1435	node = command.ForEach.CreateNull(alloc_lists=True)
1436	node.keyword = for_kw
1437
1438	num_iter_names = 0
1439	while True:
1440	w = self.cur_word
1441
1442	# Hack that makes the language more familiar:
1443	# - 'x, y' is accepted, but not 'x,y' or 'x ,y'
1444	# - 'x y' is also accepted but not idiomatic.
1445	UP_w = w
1446	if w.tag() == word_e.Compound:
1447	w = cast(CompoundWord, UP_w)
1448	if word_.LiteralId(w.parts[-1]) == Id.Lit_Comma:
1449	w.parts.pop()
1450
1451	ok, iter_name, quoted = word_.StaticEval(w)
1452	if not ok or quoted: # error: for $x
1453	p_die('Expected loop variable (a constant word)', loc.Word(w))
1454
1455	if not match.IsValidVarName(iter_name): # error: for -
1456	# TODO: consider commas?
1457	if ',' in iter_name:
1458	p_die('Loop variables look like x, y (fix spaces)',
1459	loc.Word(w))
1460	p_die('Invalid loop variable name %r' % iter_name, loc.Word(w))
1461
1462	node.iter_names.append(iter_name)
1463	num_iter_names += 1
1464	self._SetNext()
1465
1466	self._GetWord()
1467	# 'in' or 'do' or ';' or Op_Newline marks the end of variable names
1468	# Subtlety: 'var' is KW_Var and is a valid loop name
1469	if self.c_id in (Id.KW_In, Id.KW_Do) or self.c_kind == Kind.Op:
1470	break
1471
1472	if num_iter_names == 3:
1473	p_die('Unexpected word after 3 loop variables',
1474	loc.Word(self.cur_word))
1475
1476	self._NewlineOk()
1477
1478	self._GetWord()
1479	if self.c_id == Id.KW_In:
1480	expr_blame = word_.AsKeywordToken(self.cur_word)
1481
1482	self._SetNext() # skip in
1483
1484	next_id = self.w_parser.LookPastSpace()
1485	#log('%s', Id_str(next_id))
1486
1487	if next_id == Id.Op_LParen: # for x in (expr) {
1488	enode = self.w_parser.ParseYshExprForCommand()
1489	node.iterable = for_iter.YshExpr(enode, expr_blame)
1490
1491	# For simplicity, we don't accept for x in (obj); do ...
1492	self._GetWord()
1493	if self.c_id != Id.Lit_LBrace:
1494	p_die('Expected { after iterable expression',
1495	loc.Word(self.cur_word))
1496
1497	elif next_id == Id.Redir_LessGreat: # for x in <> {
1498	# <> is Id.Redir_Great - reuse this for simplicity
1499	#
1500	# Later
1501	# < is Id.Redir_Less
1502	# > is Id.Redir_Great
1503
1504	self._Eat(Id.Redir_LessGreat)
1505	#self._Eat(Id.Redir_Less)
1506	#self._SetNext()
1507	#self._Eat(Id.Redir_Great)
1508	p_die('TODO', loc.Word(self.cur_word))
1509
1510	else:
1511	semi_tok = None # type: Optional[Token]
1512	iter_words, semi_tok = self.ParseForWords()
1513	node.semi_tok = semi_tok
1514
1515	if not self.parse_opts.parse_bare_word() and len(
1516	iter_words) == 1:
1517	ok, s, quoted = word_.StaticEval(iter_words[0])
1518	if ok and match.IsValidVarName(s) and not quoted:
1519	p_die(
1520	'Surround this word with either parens or quotes (parse_bare_word)',
1521	loc.Word(iter_words[0]))
1522
1523	words2 = braces.BraceDetectAll(iter_words)
1524	words3 = word_.TildeDetectAll(words2)
1525	node.iterable = for_iter.Words(words3)
1526
1527	# Now that we know there are words, do an extra check
1528	if num_iter_names > 2:
1529	p_die('Expected at most 2 loop variables', for_kw)
1530
1531	elif self.c_id == Id.KW_Do:
1532	node.iterable = for_iter.Args # implicitly loop over "$@"
1533	# do not advance
1534
1535	elif self.c_id == Id.Op_Semi: # for x; do
1536	node.iterable = for_iter.Args # implicitly loop over "$@"
1537	self._SetNext()
1538
1539	else: # for foo BAD
1540	p_die('Unexpected word after for loop variable',
1541	loc.Word(self.cur_word))
1542
1543	self._GetWord()
1544	if self.c_id == Id.Lit_LBrace: # parse_opts.parse_brace() must be on
1545	node.body = self.ParseBraceGroup()
1546	else:
1547	node.body = self.ParseDoGroup()
1548
1549	return node
1550
1551	def ParseFor(self):
1552	# type: () -> command_t
1553	"""
1554	TODO: Update the grammar
1555
1556	for_clause : For for_name newline_ok (in for_words? for_sep)? do_group ;
1557	\| For '((' ... TODO
1558	"""
1559	ate = self._Eat(Id.KW_For)
1560	for_kw = word_.AsKeywordToken(ate)
1561
1562	self._GetWord()
1563	if self.c_id == Id.Op_DLeftParen:
1564	if not self.parse_opts.parse_dparen():
1565	p_die("Bash for loops aren't allowed (parse_dparen)",
1566	loc.Word(self.cur_word))
1567
1568	# for (( i = 0; i < 10; i++)
1569	n1 = self._ParseForExprLoop(for_kw)
1570	return self._MaybeParseRedirectList(n1)
1571	else:
1572	# for x in a b; do echo hi; done
1573	n2 = self._ParseForEachLoop(for_kw)
1574	return self._MaybeParseRedirectList(n2)
1575
1576	def _ParseConditionList(self):
1577	# type: () -> condition_t
1578	"""
1579	condition_list: command_list
1580
1581	This is a helper to parse a condition list for if commands and while/until
1582	loops. It will throw a parse error if there are no conditions in the list.
1583	"""
1584	self.allow_block = False
1585	commands = self._ParseCommandList()
1586	self.allow_block = True
1587
1588	if len(commands.children) == 0:
1589	p_die("Expected a condition", loc.Word(self.cur_word))
1590
1591	return condition.Shell(commands.children)
1592
1593	def ParseWhileUntil(self, keyword):
1594	# type: (Token) -> command.WhileUntil
1595	"""
1596	while_clause : While command_list do_group ;
1597	until_clause : Until command_list do_group ;
1598	"""
1599	self._SetNext() # skip keyword
1600
1601	if (self.parse_opts.parse_paren() and
1602	self.w_parser.LookPastSpace() == Id.Op_LParen):
1603	enode = self.w_parser.ParseYshExprForCommand()
1604	cond = condition.YshExpr(enode) # type: condition_t
1605	else:
1606	cond = self._ParseConditionList()
1607
1608	# NOTE: The LSTs will be different for OSH and YSH, but the execution
1609	# should be unchanged. To be sure we should desugar.
1610	self._GetWord()
1611	if self.parse_opts.parse_brace() and self.c_id == Id.Lit_LBrace:
1612	# while test -f foo {
1613	body_node = self.ParseBraceGroup() # type: command_t
1614	else:
1615	body_node = self.ParseDoGroup()
1616
1617	return command.WhileUntil(keyword, cond, body_node)
1618
1619	def ParseCaseArm(self):
1620	# type: () -> CaseArm
1621	"""
1622	case_item: '('? pattern ('\|' pattern)* ')'
1623	newline_ok command_term? trailer? ;
1624
1625	Looking at '(' or pattern
1626	"""
1627	self.lexer.PushHint(Id.Op_RParen, Id.Right_CasePat)
1628
1629	left_tok = location.LeftTokenForWord(self.cur_word) # ( or pat
1630
1631	if self.c_id == Id.Op_LParen: # Optional (
1632	self._SetNext()
1633
1634	pat_words = [] # type: List[word_t]
1635	while True:
1636	self._GetWord()
1637	if self.c_kind != Kind.Word:
1638	p_die('Expected case pattern', loc.Word(self.cur_word))
1639	pat_words.append(self.cur_word)
1640	self._SetNext()
1641
1642	self._GetWord()
1643	if self.c_id == Id.Op_Pipe:
1644	self._SetNext()
1645	else:
1646	break
1647
1648	ate = self._Eat(Id.Right_CasePat)
1649	middle_tok = word_.AsOperatorToken(ate)
1650
1651	self._NewlineOk()
1652
1653	self._GetWord()
1654	if self.c_id not in (Id.Op_DSemi, Id.Op_SemiAmp, Id.Op_DSemiAmp,
1655	Id.KW_Esac):
1656	c_list = self._ParseCommandTerm()
1657	action_children = c_list.children
1658	else:
1659	action_children = []
1660
1661	dsemi_tok = None # type: Token
1662	self._GetWord()
1663	if self.c_id == Id.KW_Esac: # missing last ;;
1664	pass
1665	elif self.c_id in (Id.Op_DSemi, Id.Op_SemiAmp, Id.Op_DSemiAmp):
1666	dsemi_tok = word_.AsOperatorToken(self.cur_word)
1667	self._SetNext()
1668	else:
1669	# Happens on EOF
1670	p_die('Expected ;; or esac', loc.Word(self.cur_word))
1671
1672	self._NewlineOk()
1673
1674	return CaseArm(left_tok, pat.Words(pat_words), middle_tok,
1675	action_children, dsemi_tok)
1676
1677	def ParseYshCaseArm(self, discriminant):
1678	# type: (Id_t) -> CaseArm
1679	"""
1680	case_item : pattern newline_ok brace_group newline_ok
1681	pattern : pat_words
1682	\| pat_exprs
1683	\| pat_eggex
1684	\| pat_else
1685	pat_words : pat_word (newline_ok '\|' newline_ok pat_word)*
1686	pat_exprs : pat_expr (newline_ok '\|' newline_ok pat_expr)*
1687	pat_word : WORD
1688	pat_eggex : '/' oil_eggex '/'
1689	pat_expr : '(' oil_expr ')'
1690	pat_else : '(' Id.KW_Else ')'
1691
1692	Looking at: 'pattern'
1693
1694	Note that the trailing `newline_ok` in `case_item` is handled by
1695	`ParseYshCase`. We do this because parsing that `newline_ok` returns
1696	the next "discriminant" for the next token, so it makes more sense to
1697	handle it there.
1698	"""
1699	left_tok = None # type: Token
1700	pattern = None # type: pat_t
1701
1702	if discriminant in (Id.Op_LParen, Id.Arith_Slash):
1703	# pat_exprs, pat_else or pat_eggex
1704	pattern, left_tok = self.w_parser.ParseYshCasePattern()
1705	else:
1706	# pat_words
1707	pat_words = [] # type: List[word_t]
1708	while True:
1709	self._GetWord()
1710	if self.c_kind != Kind.Word:
1711	p_die('Expected case pattern', loc.Word(self.cur_word))
1712	pat_words.append(self.cur_word)
1713	self._SetNext()
1714
1715	if not left_tok:
1716	left_tok = location.LeftTokenForWord(self.cur_word)
1717
1718	self._NewlineOk()
1719
1720	self._GetWord()
1721	if self.c_id == Id.Op_Pipe:
1722	self._SetNext()
1723	self._NewlineOk()
1724	else:
1725	break
1726	pattern = pat.Words(pat_words)
1727
1728	self._NewlineOk()
1729	action = self.ParseBraceGroup()
1730
1731	# The left token of the action is our "middle" token
1732	return CaseArm(left_tok, pattern, action.left, action.children,
1733	action.right)
1734
1735	def ParseYshCase(self, case_kw):
1736	# type: (Token) -> command.Case
1737	"""
1738	ysh_case : Case '(' expr ')' LBrace newline_ok ysh_case_arm* RBrace ;
1739
1740	Looking at: token after 'case'
1741	"""
1742	enode = self.w_parser.ParseYshExprForCommand()
1743	to_match = case_arg.YshExpr(enode)
1744
1745	ate = self._Eat(Id.Lit_LBrace)
1746	arms_start = word_.BraceToken(ate)
1747
1748	discriminant = self.w_parser.NewlineOkForYshCase()
1749
1750	# Note: for now, zero arms are accepted, just like POSIX case $x in esac
1751	arms = [] # type: List[CaseArm]
1752	while discriminant != Id.Op_RBrace:
1753	arm = self.ParseYshCaseArm(discriminant)
1754	arms.append(arm)
1755
1756	discriminant = self.w_parser.NewlineOkForYshCase()
1757
1758	# NewlineOkForYshCase leaves the lexer in lex_mode_e.Expr. So the '}'
1759	# token is read as an Id.Op_RBrace, but we need to store this as a
1760	# Id.Lit_RBrace.
1761	ate = self._Eat(Id.Op_RBrace)
1762	arms_end = word_.AsOperatorToken(ate)
1763	arms_end.id = Id.Lit_RBrace
1764
1765	return command.Case(case_kw, to_match, arms_start, arms, arms_end)
1766
1767	def ParseOldCase(self, case_kw):
1768	# type: (Token) -> command.Case
1769	"""
1770	case_clause : Case WORD newline_ok In newline_ok case_arm* Esac ;
1771
1772	-> Looking at WORD
1773
1774	FYI original POSIX case list, which takes pains for DSEMI
1775
1776	case_list: case_item (DSEMI newline_ok case_item)* DSEMI? newline_ok;
1777	"""
1778	self._GetWord()
1779	w = self.cur_word
1780	if not self.parse_opts.parse_bare_word():
1781	ok, s, quoted = word_.StaticEval(w)
1782	if ok and not quoted:
1783	p_die(
1784	"This is a constant string. You may want a variable like $x (parse_bare_word)",
1785	loc.Word(w))
1786
1787	if w.tag() != word_e.Compound:
1788	p_die("Expected a word to match against", loc.Word(w))
1789
1790	to_match = case_arg.Word(w)
1791	self._SetNext() # past WORD
1792
1793	self._NewlineOk()
1794
1795	ate = self._Eat(Id.KW_In)
1796	arms_start = word_.AsKeywordToken(ate)
1797
1798	self._NewlineOk()
1799
1800	arms = [] # type: List[CaseArm]
1801	while True:
1802	self._GetWord()
1803	if self.c_id == Id.KW_Esac:
1804	break
1805	# case arm should begin with a pattern word or (
1806	if self.c_kind != Kind.Word and self.c_id != Id.Op_LParen:
1807	break
1808
1809	arm = self.ParseCaseArm()
1810	arms.append(arm)
1811
1812	ate = self._Eat(Id.KW_Esac)
1813	arms_end = word_.AsKeywordToken(ate)
1814
1815	# no redirects yet
1816	return command.Case(case_kw, to_match, arms_start, arms, arms_end)
1817
1818	def ParseCase(self):
1819	# type: () -> command.Case
1820	"""
1821	case_clause : old_case # from POSIX
1822	\| ysh_case
1823	;
1824
1825	Looking at 'Case'
1826	"""
1827	case_kw = word_.AsKeywordToken(self.cur_word)
1828	self._SetNext() # past 'case'
1829
1830	if self.w_parser.LookPastSpace() == Id.Op_LParen:
1831	return self.ParseYshCase(case_kw)
1832	else:
1833	return self.ParseOldCase(case_kw)
1834
1835	def _ParseYshElifElse(self, if_node):
1836	# type: (command.If) -> None
1837	"""If test -f foo { echo foo.
1838
1839	} elif test -f bar; test -f spam { ^ we parsed up to here echo
1840	bar } else { echo none }
1841	"""
1842	arms = if_node.arms
1843
1844	while self.c_id == Id.KW_Elif:
1845	elif_kw = word_.AsKeywordToken(self.cur_word)
1846	self._SetNext() # skip elif
1847	if (self.parse_opts.parse_paren() and
1848	self.w_parser.LookPastSpace() == Id.Op_LParen):
1849	enode = self.w_parser.ParseYshExprForCommand()
1850	cond = condition.YshExpr(enode) # type: condition_t
1851	else:
1852	self.allow_block = False
1853	commands = self._ParseCommandList()
1854	self.allow_block = True
1855	cond = condition.Shell(commands.children)
1856
1857	body = self.ParseBraceGroup()
1858	self._GetWord()
1859
1860	arm = IfArm(elif_kw, cond, None, body.children, None)
1861	arms.append(arm)
1862
1863	self._GetWord()
1864	if self.c_id == Id.KW_Else:
1865	self._SetNext()
1866	body = self.ParseBraceGroup()
1867	if_node.else_action = body.children
1868
1869	def _ParseYshIf(self, if_kw, cond):
1870	# type: (Token, condition_t) -> command.If
1871	"""
1872	if test -f foo {
1873	# ^ we parsed up to here
1874	echo foo
1875	} elif test -f bar; test -f spam {
1876	echo bar
1877	} else {
1878	echo none
1879	}
1880	NOTE: If you do something like if test -n foo{, the parser keeps going, and
1881	the error is confusing because it doesn't point to the right place.
1882
1883	I think we might need strict_brace so that foo{ is disallowed. It has to
1884	be foo\{ or foo{a,b}. Or just turn that on with parse_brace? After you
1885	form ANY CompoundWord, make sure it's balanced for Lit_LBrace and
1886	Lit_RBrace? Maybe this is pre-parsing step in the WordParser?
1887	"""
1888	if_node = command.If.CreateNull(alloc_lists=True)
1889	if_node.if_kw = if_kw
1890
1891	body1 = self.ParseBraceGroup()
1892	# Every arm has 1 spid, unlike shell-style
1893	# TODO: We could get the spids from the brace group.
1894	arm = IfArm(if_kw, cond, None, body1.children, None)
1895
1896	if_node.arms.append(arm)
1897
1898	self._GetWord()
1899	if self.c_id in (Id.KW_Elif, Id.KW_Else):
1900	self._ParseYshElifElse(if_node)
1901	# the whole if node has the 'else' spid, unlike shell-style there's no 'fi'
1902	# spid because that's in the BraceGroup.
1903	return if_node
1904
1905	def _ParseElifElse(self, if_node):
1906	# type: (command.If) -> None
1907	"""
1908	else_part: (Elif command_list Then command_list)* Else command_list ;
1909	"""
1910	arms = if_node.arms
1911
1912	self._GetWord()
1913	while self.c_id == Id.KW_Elif:
1914	elif_kw = word_.AsKeywordToken(self.cur_word)
1915	self._SetNext() # past 'elif'
1916
1917	cond = self._ParseConditionList()
1918
1919	ate = self._Eat(Id.KW_Then)
1920	then_kw = word_.AsKeywordToken(ate)
1921
1922	body = self._ParseCommandList()
1923	arm = IfArm(elif_kw, cond, then_kw, body.children, then_kw)
1924
1925	arms.append(arm)
1926
1927	self._GetWord()
1928	if self.c_id == Id.KW_Else:
1929	else_kw = word_.AsKeywordToken(self.cur_word)
1930	self._SetNext() # past 'else'
1931	body = self._ParseCommandList()
1932	if_node.else_action = body.children
1933	else:
1934	else_kw = None
1935
1936	if_node.else_kw = else_kw
1937
1938	def ParseIf(self):
1939	# type: () -> command.If
1940	"""
1941	if_clause : If command_list Then command_list else_part? Fi ;
1942
1943	open : '{' \| Then
1944	close : '}' \| Fi
1945
1946	ysh_if : If ( command_list \| '(' expr ')' )
1947	open command_list else_part? close;
1948
1949	There are 2 conditionals here: parse_paren, then parse_brace
1950	"""
1951	if_node = command.If.CreateNull(alloc_lists=True)
1952	if_kw = word_.AsKeywordToken(self.cur_word)
1953	if_node.if_kw = if_kw
1954	self._SetNext() # past 'if'
1955
1956	if (self.parse_opts.parse_paren() and
1957	self.w_parser.LookPastSpace() == Id.Op_LParen):
1958	# if (x + 1)
1959	enode = self.w_parser.ParseYshExprForCommand()
1960	cond = condition.YshExpr(enode) # type: condition_t
1961	else:
1962	# if echo 1; echo 2; then
1963	# Remove ambiguity with if cd / {
1964	cond = self._ParseConditionList()
1965
1966	self._GetWord()
1967	if self.parse_opts.parse_brace() and self.c_id == Id.Lit_LBrace:
1968	return self._ParseYshIf(if_kw, cond)
1969
1970	ate = self._Eat(Id.KW_Then)
1971	then_kw = word_.AsKeywordToken(ate)
1972
1973	body = self._ParseCommandList()
1974
1975	# First arm
1976	arm = IfArm(if_kw, cond, then_kw, body.children, then_kw)
1977	if_node.arms.append(arm)
1978
1979	# 2nd to Nth arm
1980	if self.c_id in (Id.KW_Elif, Id.KW_Else):
1981	self._ParseElifElse(if_node)
1982
1983	ate = self._Eat(Id.KW_Fi)
1984	if_node.fi_kw = word_.AsKeywordToken(ate)
1985
1986	return if_node
1987
1988	def ParseTime(self):
1989	# type: () -> command_t
1990	"""Time [-p] pipeline.
1991
1992	According to bash help.
1993	"""
1994	time_kw = word_.AsKeywordToken(self.cur_word)
1995	self._SetNext() # skip time
1996	pipeline = self.ParsePipeline()
1997	return command.TimeBlock(time_kw, pipeline)
1998
1999	def ParseCompoundCommand(self):
2000	# type: () -> command_t
2001	"""
2002	Refactoring: we put io_redirect* here instead of in function_body and
2003	command.
2004
2005	compound_command : brace_group io_redirect*
2006	\| subshell io_redirect*
2007	\| for_clause io_redirect*
2008	\| while_clause io_redirect*
2009	\| until_clause io_redirect*
2010	\| if_clause io_redirect*
2011	\| case_clause io_redirect*
2012
2013	# bash extensions
2014	\| time_clause
2015	\| [[ BoolExpr ]]
2016	\| (( ArithExpr ))
2017	"""
2018	self._GetWord()
2019	if self.c_id == Id.Lit_LBrace:
2020	n1 = self.ParseBraceGroup()
2021	return self._MaybeParseRedirectList(n1)
2022	if self.c_id == Id.Op_LParen:
2023	n2 = self.ParseSubshell()
2024	return self._MaybeParseRedirectList(n2)
2025
2026	if self.c_id == Id.KW_For:
2027	# Note: Redirects parsed in this call. POSIX for and bash for ((
2028	# have different nodetypes.
2029	return self.ParseFor()
2030	if self.c_id in (Id.KW_While, Id.KW_Until):
2031	keyword = word_.AsKeywordToken(self.cur_word)
2032	n3 = self.ParseWhileUntil(keyword)
2033	return self._MaybeParseRedirectList(n3)
2034
2035	if self.c_id == Id.KW_If:
2036	n4 = self.ParseIf()
2037	return self._MaybeParseRedirectList(n4)
2038
2039	if self.c_id == Id.KW_Case:
2040	n5 = self.ParseCase()
2041	return self._MaybeParseRedirectList(n5)
2042
2043	if self.c_id == Id.KW_DLeftBracket:
2044	if not self.parse_opts.parse_dbracket():
2045	p_die('Bash [[ not allowed in YSH (parse_dbracket)',
2046	loc.Word(self.cur_word))
2047	n6 = self.ParseDBracket()
2048	return self._MaybeParseRedirectList(n6)
2049	if self.c_id == Id.Op_DLeftParen:
2050	if not self.parse_opts.parse_dparen():
2051	p_die(
2052	'Bash (( not allowed in YSH (parse_dparen, see OILS-ERR-14 for wart)',
2053	loc.Word(self.cur_word))
2054	n7 = self.ParseDParen()
2055	return self._MaybeParseRedirectList(n7)
2056
2057	# bash extensions: no redirects
2058	if self.c_id == Id.KW_Time:
2059	return self.ParseTime()
2060
2061	# Happens in function body, e.g. myfunc() oops
2062	p_die(
2063	'Unexpected word while parsing compound command (%s)' %
2064	Id_str(self.c_id), loc.Word(self.cur_word))
2065	assert False # for MyPy
2066
2067	def ParseFunctionDef(self):
2068	# type: () -> command.ShFunction
2069	"""
2070	function_header : fname '(' ')'
2071	function_def : function_header newline_ok function_body ;
2072
2073	Precondition: Looking at the function name.
2074
2075	NOTE: There is an ambiguity with:
2076
2077	function foo ( echo hi ) and
2078	function foo () ( echo hi )
2079
2080	Bash only accepts the latter, though it doesn't really follow a grammar.
2081	"""
2082	word0 = cast(CompoundWord, self.cur_word) # caller ensures validity
2083	name = word_.ShFunctionName(word0)
2084	if len(name) == 0: # example: foo$x is invalid
2085	p_die('Invalid function name', loc.Word(word0))
2086
2087	part0 = word0.parts[0]
2088	# If we got a non-empty string from ShFunctionName, this should be true.
2089	assert part0.tag() == word_part_e.Literal
2090	blame_tok = cast(Token, part0) # for ctx_VarChecker
2091
2092	self._SetNext() # move past function name
2093
2094	# Must be true because of lookahead
2095	self._GetWord()
2096	assert self.c_id == Id.Op_LParen, self.cur_word
2097
2098	self.lexer.PushHint(Id.Op_RParen, Id.Right_ShFunction)
2099	self._SetNext()
2100
2101	self._GetWord()
2102	if self.c_id == Id.Right_ShFunction:
2103	# 'f ()' implies a function definition, since invoking it with no args
2104	# would just be 'f'
2105	self._SetNext()
2106
2107	self._NewlineOk()
2108
2109	func = command.ShFunction.CreateNull()
2110	func.name = name
2111	with ctx_VarChecker(self.var_checker, blame_tok):
2112	func.body = self.ParseCompoundCommand()
2113
2114	func.name_tok = location.LeftTokenForCompoundWord(word0)
2115	return func
2116	else:
2117	p_die('Expected ) in function definition', loc.Word(self.cur_word))
2118	return None
2119
2120	def ParseKshFunctionDef(self):
2121	# type: () -> command.ShFunction
2122	"""
2123	ksh_function_def : 'function' fname ( '(' ')' )? newline_ok function_body
2124	"""
2125	keyword_tok = word_.AsKeywordToken(self.cur_word)
2126
2127	self._SetNext() # skip past 'function'
2128	self._GetWord()
2129
2130	cur_word = cast(CompoundWord, self.cur_word) # caller ensures validity
2131	name = word_.ShFunctionName(cur_word)
2132	if len(name) == 0: # example: foo$x is invalid
2133	p_die('Invalid KSH-style function name', loc.Word(cur_word))
2134
2135	name_word = self.cur_word
2136	self._SetNext() # skip past 'function name
2137
2138	self._GetWord()
2139	if self.c_id == Id.Op_LParen:
2140	self.lexer.PushHint(Id.Op_RParen, Id.Right_ShFunction)
2141	self._SetNext()
2142	self._Eat(Id.Right_ShFunction)
2143
2144	self._NewlineOk()
2145
2146	func = command.ShFunction.CreateNull()
2147	func.name = name
2148	with ctx_VarChecker(self.var_checker, keyword_tok):
2149	func.body = self.ParseCompoundCommand()
2150
2151	func.keyword = keyword_tok
2152	func.name_tok = location.LeftTokenForWord(name_word)
2153	return func
2154
2155	def ParseYshProc(self):
2156	# type: () -> Proc
2157	node = Proc.CreateNull(alloc_lists=True)
2158
2159	keyword_tok = word_.AsKeywordToken(self.cur_word)
2160	node.keyword = keyword_tok
2161
2162	with ctx_VarChecker(self.var_checker, keyword_tok):
2163	with ctx_CmdMode(self, cmd_mode_e.Proc):
2164	self.w_parser.ParseProc(node)
2165	if node.sig.tag() == proc_sig_e.Closed: # Register params
2166	sig = cast(proc_sig.Closed, node.sig)
2167
2168	# Treat 3 kinds of params as variables.
2169	wp = sig.word
2170	if wp:
2171	for param in wp.params:
2172	self.var_checker.Check(Id.KW_Var, param.name,
2173	param.blame_tok)
2174	if wp.rest_of:
2175	r = wp.rest_of
2176	self.var_checker.Check(Id.KW_Var, r.name,
2177	r.blame_tok)
2178	# We COULD register __out here but it would require a different API.
2179	#if param.prefix and param.prefix.id == Id.Arith_Colon:
2180	# self.var_checker.Check(Id.KW_Var, '__' + param.name)
2181
2182	posit = sig.positional
2183	if posit:
2184	for param in posit.params:
2185	self.var_checker.Check(Id.KW_Var, param.name,
2186	param.blame_tok)
2187	if posit.rest_of:
2188	r = posit.rest_of
2189	self.var_checker.Check(Id.KW_Var, r.name,
2190	r.blame_tok)
2191
2192	named = sig.named
2193	if named:
2194	for param in named.params:
2195	self.var_checker.Check(Id.KW_Var, param.name,
2196	param.blame_tok)
2197	if named.rest_of:
2198	r = named.rest_of
2199	self.var_checker.Check(Id.KW_Var, r.name,
2200	r.blame_tok)
2201
2202	if sig.block_param:
2203	b = sig.block_param
2204	self.var_checker.Check(Id.KW_Var, b.name, b.blame_tok)
2205
2206	self._SetNext()
2207	node.body = self.ParseBraceGroup()
2208	# No redirects for YSH procs (only at call site)
2209
2210	return node
2211
2212	def ParseYshFunc(self):
2213	# type: () -> Func
2214	"""
2215	ysh_func: (
2216	Expr_Name '(' [func_params] [';' func_params] ')' ['=>' type_expr] '{'
2217	)
2218	Looking at KW_Func
2219	"""
2220	node = Func.CreateNull(alloc_lists=True)
2221
2222	keyword_tok = word_.AsKeywordToken(self.cur_word)
2223	node.keyword = keyword_tok
2224
2225	with ctx_VarChecker(self.var_checker, keyword_tok):
2226	self.w_parser.ParseFunc(node)
2227
2228	posit = node.positional
2229	if posit:
2230	for param in posit.params:
2231	self.var_checker.Check(Id.KW_Var, param.name,
2232	param.blame_tok)
2233	if posit.rest_of:
2234	r = posit.rest_of
2235	self.var_checker.Check(Id.KW_Var, r.name, r.blame_tok)
2236
2237	named = node.named
2238	if named:
2239	for param in named.params:
2240	self.var_checker.Check(Id.KW_Var, param.name,
2241	param.blame_tok)
2242	if named.rest_of:
2243	r = named.rest_of
2244	self.var_checker.Check(Id.KW_Var, r.name, r.blame_tok)
2245
2246	self._SetNext()
2247	with ctx_CmdMode(self, cmd_mode_e.Func):
2248	node.body = self.ParseBraceGroup()
2249
2250	return node
2251
2252	def ParseCoproc(self):
2253	# type: () -> command_t
2254	"""
2255	TODO: command.Coproc?
2256	"""
2257	raise NotImplementedError()
2258
2259	def ParseSubshell(self):
2260	# type: () -> command.Subshell
2261	"""
2262	subshell : '(' compound_list ')'
2263
2264	Looking at Op_LParen
2265	"""
2266	left = word_.AsOperatorToken(self.cur_word)
2267	self._SetNext() # skip past (
2268
2269	# Ensure that something $( (cd / && pwd) ) works. If ) is already on the
2270	# translation stack, we want to delay it.
2271
2272	self.lexer.PushHint(Id.Op_RParen, Id.Right_Subshell)
2273
2274	c_list = self._ParseCommandList()
2275	if len(c_list.children) == 1:
2276	child = c_list.children[0]
2277	else:
2278	child = c_list
2279
2280	ate = self._Eat(Id.Right_Subshell)
2281	right = word_.AsOperatorToken(ate)
2282
2283	return command.Subshell(left, child, right)
2284
2285	def ParseDBracket(self):
2286	# type: () -> command.DBracket
2287	"""Pass the underlying word parser off to the boolean expression
2288	parser."""
2289	left = word_.AsKeywordToken(self.cur_word)
2290	# TODO: Test interactive. Without closing ]], you should get > prompt
2291	# (PS2)
2292
2293	self._SetNext() # skip [[
2294	b_parser = bool_parse.BoolParser(self.w_parser)
2295	bnode, right = b_parser.Parse() # May raise
2296	return command.DBracket(left, bnode, right)
2297
2298	def ParseDParen(self):
2299	# type: () -> command.DParen
2300	left = word_.AsOperatorToken(self.cur_word)
2301
2302	self._SetNext() # skip ((
2303	anode, right = self.w_parser.ReadDParen()
2304	assert anode is not None
2305
2306	return command.DParen(left, anode, right)
2307
2308	def ParseCommand(self):
2309	# type: () -> command_t
2310	"""
2311	command : simple_command
2312	\| compound_command # OSH edit: io_redirect* folded in
2313	\| function_def
2314	\| ksh_function_def
2315
2316	# YSH extensions
2317	\| proc NAME ...
2318	\| typed proc NAME ...
2319	\| func NAME ...
2320	\| const ...
2321	\| var ...
2322	\| setglobal ...
2323	\| setref ...
2324	\| setvar ...
2325	\| call EXPR
2326	\| = EXPR
2327	;
2328
2329	Note: the reason const / var are not part of compound_command is because
2330	they can't be alone in a shell function body.
2331
2332	Example:
2333	This is valid shell f() if true; then echo hi; fi
2334	This is invalid f() var x = 1
2335	"""
2336	if self._AtSecondaryKeyword():
2337	p_die('Unexpected word when parsing command',
2338	loc.Word(self.cur_word))
2339
2340	# YSH Extensions
2341
2342	if self.c_id == Id.KW_Proc: # proc p { ... }
2343	# proc is hidden because of the 'local reasoning' principle. Code
2344	# inside procs should be YSH, full stop. That means ysh:upgrade is
2345	# on.
2346	if self.parse_opts.parse_proc():
2347	return self.ParseYshProc()
2348	else:
2349	# 2024-02: This avoids bad syntax errors if you type YSH code
2350	# into OSH
2351	# proc p (x) { echo hi } would actually be parsed as a
2352	# command.Simple! Shell compatibility: quote 'proc'
2353	p_die("proc is a YSH keyword, but this is OSH.",
2354	loc.Word(self.cur_word))
2355
2356	if self.c_id == Id.KW_Typed: # typed proc p () { ... }
2357	self._SetNext()
2358	self._GetWord()
2359	if self.c_id != Id.KW_Proc:
2360	p_die("Expected 'proc' after 'typed'", loc.Word(self.cur_word))
2361
2362	if self.parse_opts.parse_proc():
2363	return self.ParseYshProc()
2364	else:
2365	p_die("typed is a YSH keyword, but this is OSH.",
2366	loc.Word(self.cur_word))
2367
2368	if self.c_id == Id.KW_Func: # func f(x) { ... }
2369	if self.parse_opts.parse_func():
2370	return self.ParseYshFunc()
2371	else:
2372	# Same reasoning as above, for 'proc'
2373	p_die("func is a YSH keyword, but this is OSH.",
2374	loc.Word(self.cur_word))
2375
2376	if self.c_id == Id.KW_Const and self.cmd_mode != cmd_mode_e.Shell:
2377	p_die("const can't be inside proc or func. Use var instead.",
2378	loc.Word(self.cur_word))
2379
2380	if self.c_id in (Id.KW_Var, Id.KW_Const): # var x = 1
2381	keyword_id = self.c_id
2382	kw_token = word_.LiteralToken(self.cur_word)
2383	self._SetNext()
2384	n8 = self.w_parser.ParseVarDecl(kw_token)
2385	for lhs in n8.lhs:
2386	self.var_checker.Check(keyword_id, lhs.name, lhs.left)
2387	return n8
2388
2389	if self.c_id in (Id.KW_SetVar, Id.KW_SetGlobal):
2390	kw_token = word_.LiteralToken(self.cur_word)
2391	self._SetNext()
2392	n9 = self.w_parser.ParseMutation(kw_token, self.var_checker)
2393	return n9
2394
2395	if self.c_id in (Id.KW_Call, Id.Lit_Equals):
2396	# = 42 + a[i]
2397	# call mylist->append('x')
2398
2399	keyword = word_.LiteralToken(self.cur_word)
2400	assert keyword is not None
2401	self._SetNext()
2402	enode = self.w_parser.ParseCommandExpr()
2403	return command.Expr(keyword, enode)
2404
2405	if self.c_id == Id.KW_Function:
2406	return self.ParseKshFunctionDef()
2407
2408	if self.c_id in (Id.KW_DLeftBracket, Id.Op_DLeftParen, Id.Op_LParen,
2409	Id.Lit_LBrace, Id.KW_For, Id.KW_While, Id.KW_Until,
2410	Id.KW_If, Id.KW_Case, Id.KW_Time):
2411	return self.ParseCompoundCommand()
2412
2413	# Syntax error for '}' starting a line, which all shells disallow.
2414	if self.c_id == Id.Lit_RBrace:
2415	p_die('Unexpected right brace', loc.Word(self.cur_word))
2416
2417	if self.c_kind == Kind.Redir: # Leading redirect
2418	return self.ParseSimpleCommand()
2419
2420	if self.c_kind == Kind.Word:
2421	# ensured by Kind.Word
2422	cur_word = cast(CompoundWord, self.cur_word)
2423
2424	# NOTE: At the top level, only Token and Compound are possible.
2425	# Can this be modelled better in the type system, removing asserts?
2426	#
2427	# TODO: This can be a proc INVOCATION! (Doesn't even need parse_paren)
2428	# Problem: We have to distinguish f( ) { echo ; } and myproc (x, y)
2429	# That requires 2 tokens of lookahead, which we don't have
2430	#
2431	# Or maybe we don't just have ParseSimpleCommand -- we will have
2432	# ParseYshCommand or something
2433
2434	if (self.w_parser.LookAheadFuncParens() and
2435	not word_.IsVarLike(cur_word)):
2436	return self.ParseFunctionDef() # f() { echo; } # function
2437
2438	# Parse x = 1+2*3 when inside HayNode { } blocks
2439	parts = cur_word.parts
2440	if self.parse_opts.parse_equals() and len(parts) == 1:
2441	part0 = parts[0]
2442	if part0.tag() == word_part_e.Literal:
2443	tok = cast(Token, part0)
2444	if (tok.id == Id.Lit_Chars and
2445	self.w_parser.LookPastSpace() == Id.Lit_Equals and
2446	match.IsValidVarName(lexer.LazyStr(tok))):
2447
2448	if (len(self.hay_attrs_stack) and
2449	self.hay_attrs_stack[-1]):
2450	# Note: no static var_checker.Check() for bare assignment
2451	enode = self.w_parser.ParseBareDecl()
2452	self._SetNext() # Somehow this is necessary
2453	# TODO: Use BareDecl here. Well, do that when we
2454	# treat it as const or lazy.
2455	return command.VarDecl(
2456	None,
2457	[NameType(tok, lexer.TokenVal(tok), None)],
2458	enode)
2459	else:
2460	self._SetNext()
2461	self._GetWord()
2462	p_die(
2463	'Unexpected = (Hint: use var/setvar, or quote it)',
2464	loc.Word(self.cur_word))
2465
2466	# echo foo
2467	# f=(a b c) # array
2468	# array[1+2]+=1
2469	return self.ParseSimpleCommand()
2470
2471	if self.c_kind == Kind.Eof:
2472	p_die("Unexpected EOF while parsing command",
2473	loc.Word(self.cur_word))
2474
2475	# NOTE: This only happens in batch mode in the second turn of the loop!
2476	# e.g. )
2477	p_die("Invalid word while parsing command", loc.Word(self.cur_word))
2478
2479	assert False # for MyPy
2480
2481	def ParsePipeline(self):
2482	# type: () -> command_t
2483	"""
2484	pipeline : Bang? command ( '\|' newline_ok command )* ;
2485	"""
2486	negated = None # type: Optional[Token]
2487
2488	self._GetWord()
2489	if self.c_id == Id.KW_Bang:
2490	negated = word_.AsKeywordToken(self.cur_word)
2491	self._SetNext()
2492
2493	child = self.ParseCommand()
2494	assert child is not None
2495
2496	children = [child]
2497
2498	self._GetWord()
2499	if self.c_id not in (Id.Op_Pipe, Id.Op_PipeAmp):
2500	if negated is not None:
2501	node = command.Pipeline(negated, children, [])
2502	return node
2503	else:
2504	return child # no pipeline
2505
2506	# \| or \|&
2507	ops = [] # type: List[Token]
2508	while True:
2509	op = word_.AsOperatorToken(self.cur_word)
2510	ops.append(op)
2511
2512	self._SetNext() # skip past Id.Op_Pipe or Id.Op_PipeAmp
2513	self._NewlineOk()
2514
2515	child = self.ParseCommand()
2516	children.append(child)
2517
2518	self._GetWord()
2519	if self.c_id not in (Id.Op_Pipe, Id.Op_PipeAmp):
2520	break
2521
2522	return command.Pipeline(negated, children, ops)
2523
2524	def ParseAndOr(self):
2525	# type: () -> command_t
2526	self._GetWord()
2527	if self.c_id == Id.Lit_TDot:
2528	# We got '...', so parse in multiline mode
2529	self._SetNext()
2530	with word_.ctx_Multiline(self.w_parser):
2531	return self._ParseAndOr()
2532
2533	# Parse in normal mode, not multiline
2534	return self._ParseAndOr()
2535
2536	def _ParseAndOr(self):
2537	# type: () -> command_t
2538	"""
2539	and_or : and_or ( AND_IF \| OR_IF ) newline_ok pipeline
2540	\| pipeline
2541
2542	Note that it is left recursive and left associative. We parse it
2543	iteratively with a token of lookahead.
2544	"""
2545	child = self.ParsePipeline()
2546	assert child is not None
2547
2548	self._GetWord()
2549	if self.c_id not in (Id.Op_DPipe, Id.Op_DAmp):
2550	return child
2551
2552	ops = [] # type: List[Token]
2553	children = [child]
2554
2555	while True:
2556	ops.append(word_.AsOperatorToken(self.cur_word))
2557
2558	self._SetNext() # skip past \|\| &&
2559	self._NewlineOk()
2560
2561	child = self.ParsePipeline()
2562	children.append(child)
2563
2564	self._GetWord()
2565	if self.c_id not in (Id.Op_DPipe, Id.Op_DAmp):
2566	break
2567
2568	return command.AndOr(children, ops)
2569
2570	# NOTE: _ParseCommandLine and _ParseCommandTerm are similar, but different.
2571
2572	# At the top level, we execute after every line, e.g. to
2573	# - process alias (a form of dynamic parsing)
2574	# - process 'exit', because invalid syntax might appear after it
2575
2576	# On the other hand, for a while loop body, we parse the whole thing at once,
2577	# and then execute it. We don't want to parse it over and over again!
2578
2579	# COMPARE
2580	# command_line : and_or (sync_op and_or)* trailer? ; # TOP LEVEL
2581	# command_term : and_or (trailer and_or)* ; # CHILDREN
2582
2583	def _ParseCommandLine(self):
2584	# type: () -> command_t
2585	"""
2586	command_line : and_or (sync_op and_or)* trailer? ;
2587	trailer : sync_op newline_ok
2588	\| NEWLINES;
2589	sync_op : '&' \| ';';
2590
2591	NOTE: This rule causes LL(k > 1) behavior. We would have to peek to see if
2592	there is another command word after the sync op.
2593
2594	But it's easier to express imperatively. Do the following in a loop:
2595	1. ParseAndOr
2596	2. Peek.
2597	a. If there's a newline, then return. (We're only parsing a single
2598	line.)
2599	b. If there's a sync_op, process it. Then look for a newline and
2600	return. Otherwise, parse another AndOr.
2601	"""
2602	# This END_LIST is slightly different than END_LIST in _ParseCommandTerm.
2603	# I don't think we should add anything else here; otherwise it will be
2604	# ignored at the end of ParseInteractiveLine(), e.g. leading to bug #301.
2605	END_LIST = [Id.Op_Newline, Id.Eof_Real]
2606
2607	children = [] # type: List[command_t]
2608	done = False
2609	while not done:
2610	child = self.ParseAndOr()
2611
2612	self._GetWord()
2613	if self.c_id in (Id.Op_Semi, Id.Op_Amp):
2614	tok = cast(Token, self.cur_word) # for MyPy
2615	child = command.Sentence(child, tok)
2616	self._SetNext()
2617
2618	self._GetWord()
2619	if self.c_id in END_LIST:
2620	done = True
2621
2622	elif self.c_id in END_LIST:
2623	done = True
2624
2625	else:
2626	# e.g. echo a(b)
2627	p_die(
2628	'Invalid word while parsing command line (%s)' %
2629	Id_str(self.c_id), loc.Word(self.cur_word))
2630
2631	children.append(child)
2632
2633	# Simplify the AST.
2634	if len(children) > 1:
2635	return command.CommandList(children)
2636	else:
2637	return children[0]
2638
2639	def _ParseCommandTerm(self):
2640	# type: () -> command.CommandList
2641	""""
2642	command_term : and_or (trailer and_or)* ;
2643	trailer : sync_op newline_ok
2644	\| NEWLINES;
2645	sync_op : '&' \| ';';
2646
2647	This is handled in imperative style, like _ParseCommandLine.
2648	Called by _ParseCommandList for all blocks, and also for ParseCaseArm,
2649	which is slightly different. (HOW? Is it the DSEMI?)
2650
2651	Returns:
2652	syntax_asdl.command
2653	"""
2654	# Token types that will end the command term.
2655	END_LIST = [
2656	self.eof_id, Id.Right_Subshell, Id.Lit_RBrace, Id.Op_DSemi,
2657	Id.Op_SemiAmp, Id.Op_DSemiAmp
2658	]
2659
2660	# NOTE: This is similar to _ParseCommandLine.
2661	#
2662	# - Why aren't we doing END_LIST in _ParseCommandLine?
2663	# - Because you will never be inside $() at the top level.
2664	# - We also know it will end in a newline. It can't end in "fi"!
2665	# - example: if true; then { echo hi; } fi
2666
2667	children = [] # type: List[command_t]
2668	done = False
2669	while not done:
2670	# Most keywords are valid "first words". But do/done/then do not BEGIN
2671	# commands, so they are not valid.
2672	if self._AtSecondaryKeyword():
2673	break
2674
2675	child = self.ParseAndOr()
2676
2677	self._GetWord()
2678	if self.c_id == Id.Op_Newline:
2679	self._SetNext()
2680
2681	self._GetWord()
2682	if self.c_id in END_LIST:
2683	done = True
2684
2685	elif self.c_id in (Id.Op_Semi, Id.Op_Amp):
2686	tok = cast(Token, self.cur_word) # for MyPy
2687	child = command.Sentence(child, tok)
2688	self._SetNext()
2689
2690	self._GetWord()
2691	if self.c_id == Id.Op_Newline:
2692	self._SetNext() # skip over newline
2693
2694	# Test if we should keep going. There might be another command after
2695	# the semi and newline.
2696	self._GetWord()
2697	if self.c_id in END_LIST: # \n EOF
2698	done = True
2699
2700	elif self.c_id in END_LIST: # ; EOF
2701	done = True
2702
2703	elif self.c_id in END_LIST: # EOF
2704	done = True
2705
2706	# For if test -f foo; test -f bar {
2707	elif self.parse_opts.parse_brace() and self.c_id == Id.Lit_LBrace:
2708	done = True
2709
2710	elif self.c_kind != Kind.Word:
2711	# e.g. f() { echo (( x )) ; }
2712	# but can't fail on 'fi fi', see osh/cmd_parse_test.py
2713
2714	#log("Invalid %s", self.cur_word)
2715	p_die("Invalid word while parsing command list",
2716	loc.Word(self.cur_word))
2717
2718	children.append(child)
2719
2720	return command.CommandList(children)
2721
2722	def _ParseCommandList(self):
2723	# type: () -> command.CommandList
2724	"""
2725	command_list : newline_ok command_term trailer? ;
2726
2727	This one is called by all the compound commands. It's basically a command
2728	block.
2729
2730	NOTE: Rather than translating the CFG directly, the code follows a style
2731	more like this: more like this: (and_or trailer)+. It makes capture
2732	easier.
2733	"""
2734	self._NewlineOk()
2735	return self._ParseCommandTerm()
2736
2737	def ParseLogicalLine(self):
2738	# type: () -> command_t
2739	"""Parse a single line for main_loop.
2740
2741	A wrapper around _ParseCommandLine(). Similar but not identical to
2742	_ParseCommandList() and ParseCommandSub().
2743
2744	Raises:
2745	ParseError
2746	"""
2747	self._NewlineOk()
2748	self._GetWord()
2749	if self.c_id == Id.Eof_Real:
2750	return None # main loop checks for here docs
2751	node = self._ParseCommandLine()
2752	return node
2753
2754	def ParseInteractiveLine(self):
2755	# type: () -> parse_result_t
2756	"""Parse a single line for Interactive main_loop.
2757
2758	Different from ParseLogicalLine because newlines are handled differently.
2759
2760	Raises:
2761	ParseError
2762	"""
2763	self._GetWord()
2764	if self.c_id == Id.Op_Newline:
2765	return parse_result.EmptyLine
2766	if self.c_id == Id.Eof_Real:
2767	return parse_result.Eof
2768
2769	node = self._ParseCommandLine()
2770	return parse_result.Node(node)
2771
2772	def ParseCommandSub(self):
2773	# type: () -> command_t
2774	"""Parse $(echo hi) and `echo hi` for word_parse.py.
2775
2776	They can have multiple lines, like this: echo $( echo one echo
2777	two )
2778	"""
2779	self._NewlineOk()
2780
2781	self._GetWord()
2782	if self.c_kind == Kind.Eof: # e.g. $()
2783	return command.NoOp
2784
2785	c_list = self._ParseCommandTerm()
2786	if len(c_list.children) == 1:
2787	return c_list.children[0]
2788	else:
2789	return c_list
2790
2791	def CheckForPendingHereDocs(self):
2792	# type: () -> None
2793	# NOTE: This happens when there is no newline at the end of a file, like
2794	# osh -c 'cat <<EOF'
2795	if len(self.pending_here_docs):
2796	node = self.pending_here_docs[0] # Just show the first one?
2797	h = cast(redir_param.HereDoc, node.arg)
2798	p_die('Unterminated here doc began here', loc.Word(h.here_begin))
2799
2800
2801	# vim: sw=4