qemu/scripts/qapi/parser.py
John Snow d4092ffa26 qapi/parser: add docstrings
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210519183951.3946870-16-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Doc string spacing tweaked slightly]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2021-05-20 17:10:09 +02:00

769 lines
28 KiB
Python

# -*- coding: utf-8 -*-
#
# QAPI schema parser
#
# Copyright IBM, Corp. 2011
# Copyright (c) 2013-2019 Red Hat Inc.
#
# Authors:
# Anthony Liguori <aliguori@us.ibm.com>
# Markus Armbruster <armbru@redhat.com>
# Marc-André Lureau <marcandre.lureau@redhat.com>
# Kevin Wolf <kwolf@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2.
# See the COPYING file in the top-level directory.
from collections import OrderedDict
import os
import re
from typing import (
Dict,
List,
Optional,
Set,
Union,
)
from .common import must_match
from .error import QAPISemError, QAPISourceError
from .source import QAPISourceInfo
# Return value alias for get_expr().
_ExprValue = Union[List[object], Dict[str, object], str, bool]
class QAPIParseError(QAPISourceError):
"""Error class for all QAPI schema parsing errors."""
def __init__(self, parser: 'QAPISchemaParser', msg: str):
col = 1
for ch in parser.src[parser.line_pos:parser.pos]:
if ch == '\t':
col = (col + 7) % 8 + 1
else:
col += 1
super().__init__(parser.info, msg, col)
class QAPISchemaParser:
"""
Parse QAPI schema source.
Parse a JSON-esque schema file and process directives. See
qapi-code-gen.txt section "Schema Syntax" for the exact syntax.
Grammatical validation is handled later by `expr.check_exprs()`.
:param fname: Source file name.
:param previously_included:
The absolute names of previously included source files,
if being invoked from another parser.
:param incl_info:
`QAPISourceInfo` belonging to the parent module.
``None`` implies this is the root module.
:ivar exprs: Resulting parsed expressions.
:ivar docs: Resulting parsed documentation blocks.
:raise OSError: For problems reading the root schema document.
:raise QAPIError: For errors in the schema source.
"""
def __init__(self,
fname: str,
previously_included: Optional[Set[str]] = None,
incl_info: Optional[QAPISourceInfo] = None):
self._fname = fname
self._included = previously_included or set()
self._included.add(os.path.abspath(self._fname))
self.src = ''
# Lexer state (see `accept` for details):
self.info = QAPISourceInfo(self._fname, incl_info)
self.tok: Union[None, str] = None
self.pos = 0
self.cursor = 0
self.val: Optional[Union[bool, str]] = None
self.line_pos = 0
# Parser output:
self.exprs: List[Dict[str, object]] = []
self.docs: List[QAPIDoc] = []
# Showtime!
self._parse()
def _parse(self) -> None:
"""
Parse the QAPI schema document.
:return: None. Results are stored in ``.exprs`` and ``.docs``.
"""
cur_doc = None
# May raise OSError; allow the caller to handle it.
with open(self._fname, 'r', encoding='utf-8') as fp:
self.src = fp.read()
if self.src == '' or self.src[-1] != '\n':
self.src += '\n'
# Prime the lexer:
self.accept()
# Parse until done:
while self.tok is not None:
info = self.info
if self.tok == '#':
self.reject_expr_doc(cur_doc)
for cur_doc in self.get_doc(info):
self.docs.append(cur_doc)
continue
expr = self.get_expr()
if not isinstance(expr, dict):
raise QAPISemError(
info, "top-level expression must be an object")
if 'include' in expr:
self.reject_expr_doc(cur_doc)
if len(expr) != 1:
raise QAPISemError(info, "invalid 'include' directive")
include = expr['include']
if not isinstance(include, str):
raise QAPISemError(info,
"value of 'include' must be a string")
incl_fname = os.path.join(os.path.dirname(self._fname),
include)
self.exprs.append({'expr': {'include': incl_fname},
'info': info})
exprs_include = self._include(include, info, incl_fname,
self._included)
if exprs_include:
self.exprs.extend(exprs_include.exprs)
self.docs.extend(exprs_include.docs)
elif "pragma" in expr:
self.reject_expr_doc(cur_doc)
if len(expr) != 1:
raise QAPISemError(info, "invalid 'pragma' directive")
pragma = expr['pragma']
if not isinstance(pragma, dict):
raise QAPISemError(
info, "value of 'pragma' must be an object")
for name, value in pragma.items():
self._pragma(name, value, info)
else:
expr_elem = {'expr': expr,
'info': info}
if cur_doc:
if not cur_doc.symbol:
raise QAPISemError(
cur_doc.info, "definition documentation required")
expr_elem['doc'] = cur_doc
self.exprs.append(expr_elem)
cur_doc = None
self.reject_expr_doc(cur_doc)
@staticmethod
def reject_expr_doc(doc: Optional['QAPIDoc']) -> None:
if doc and doc.symbol:
raise QAPISemError(
doc.info,
"documentation for '%s' is not followed by the definition"
% doc.symbol)
@staticmethod
def _include(include: str,
info: QAPISourceInfo,
incl_fname: str,
previously_included: Set[str]
) -> Optional['QAPISchemaParser']:
incl_abs_fname = os.path.abspath(incl_fname)
# catch inclusion cycle
inf: Optional[QAPISourceInfo] = info
while inf:
if incl_abs_fname == os.path.abspath(inf.fname):
raise QAPISemError(info, "inclusion loop for %s" % include)
inf = inf.parent
# skip multiple include of the same file
if incl_abs_fname in previously_included:
return None
try:
return QAPISchemaParser(incl_fname, previously_included, info)
except OSError as err:
raise QAPISemError(
info,
f"can't read include file '{incl_fname}': {err.strerror}"
) from err
@staticmethod
def _pragma(name: str, value: object, info: QAPISourceInfo) -> None:
def check_list_str(name: str, value: object) -> List[str]:
if (not isinstance(value, list) or
any(not isinstance(elt, str) for elt in value)):
raise QAPISemError(
info,
"pragma %s must be a list of strings" % name)
return value
pragma = info.pragma
if name == 'doc-required':
if not isinstance(value, bool):
raise QAPISemError(info,
"pragma 'doc-required' must be boolean")
pragma.doc_required = value
elif name == 'command-name-exceptions':
pragma.command_name_exceptions = check_list_str(name, value)
elif name == 'command-returns-exceptions':
pragma.command_returns_exceptions = check_list_str(name, value)
elif name == 'member-name-exceptions':
pragma.member_name_exceptions = check_list_str(name, value)
else:
raise QAPISemError(info, "unknown pragma '%s'" % name)
def accept(self, skip_comment: bool = True) -> None:
"""
Read and store the next token.
:param skip_comment:
When false, return COMMENT tokens ("#").
This is used when reading documentation blocks.
:return:
None. Several instance attributes are updated instead:
- ``.tok`` represents the token type. See below for values.
- ``.info`` describes the token's source location.
- ``.val`` is the token's value, if any. See below.
- ``.pos`` is the buffer index of the first character of
the token.
* Single-character tokens:
These are "{", "}", ":", ",", "[", and "]".
``.tok`` holds the single character and ``.val`` is None.
* Multi-character tokens:
* COMMENT:
This token is not normally returned by the lexer, but it can
be when ``skip_comment`` is False. ``.tok`` is "#", and
``.val`` is a string including all chars until end-of-line,
including the "#" itself.
* STRING:
``.tok`` is "'", the single quote. ``.val`` contains the
string, excluding the surrounding quotes.
* TRUE and FALSE:
``.tok`` is either "t" or "f", ``.val`` will be the
corresponding bool value.
* EOF:
``.tok`` and ``.val`` will both be None at EOF.
"""
while True:
self.tok = self.src[self.cursor]
self.pos = self.cursor
self.cursor += 1
self.val = None
if self.tok == '#':
if self.src[self.cursor] == '#':
# Start of doc comment
skip_comment = False
self.cursor = self.src.find('\n', self.cursor)
if not skip_comment:
self.val = self.src[self.pos:self.cursor]
return
elif self.tok in '{}:,[]':
return
elif self.tok == "'":
# Note: we accept only printable ASCII
string = ''
esc = False
while True:
ch = self.src[self.cursor]
self.cursor += 1
if ch == '\n':
raise QAPIParseError(self, "missing terminating \"'\"")
if esc:
# Note: we recognize only \\ because we have
# no use for funny characters in strings
if ch != '\\':
raise QAPIParseError(self,
"unknown escape \\%s" % ch)
esc = False
elif ch == '\\':
esc = True
continue
elif ch == "'":
self.val = string
return
if ord(ch) < 32 or ord(ch) >= 127:
raise QAPIParseError(
self, "funny character in string")
string += ch
elif self.src.startswith('true', self.pos):
self.val = True
self.cursor += 3
return
elif self.src.startswith('false', self.pos):
self.val = False
self.cursor += 4
return
elif self.tok == '\n':
if self.cursor == len(self.src):
self.tok = None
return
self.info = self.info.next_line()
self.line_pos = self.cursor
elif not self.tok.isspace():
# Show up to next structural, whitespace or quote
# character
match = must_match('[^[\\]{}:,\\s\'"]+',
self.src[self.cursor-1:])
raise QAPIParseError(self, "stray '%s'" % match.group(0))
def get_members(self) -> Dict[str, object]:
expr: Dict[str, object] = OrderedDict()
if self.tok == '}':
self.accept()
return expr
if self.tok != "'":
raise QAPIParseError(self, "expected string or '}'")
while True:
key = self.val
assert isinstance(key, str) # Guaranteed by tok == "'"
self.accept()
if self.tok != ':':
raise QAPIParseError(self, "expected ':'")
self.accept()
if key in expr:
raise QAPIParseError(self, "duplicate key '%s'" % key)
expr[key] = self.get_expr()
if self.tok == '}':
self.accept()
return expr
if self.tok != ',':
raise QAPIParseError(self, "expected ',' or '}'")
self.accept()
if self.tok != "'":
raise QAPIParseError(self, "expected string")
def get_values(self) -> List[object]:
expr: List[object] = []
if self.tok == ']':
self.accept()
return expr
if self.tok not in tuple("{['tf"):
raise QAPIParseError(
self, "expected '{', '[', ']', string, or boolean")
while True:
expr.append(self.get_expr())
if self.tok == ']':
self.accept()
return expr
if self.tok != ',':
raise QAPIParseError(self, "expected ',' or ']'")
self.accept()
def get_expr(self) -> _ExprValue:
expr: _ExprValue
if self.tok == '{':
self.accept()
expr = self.get_members()
elif self.tok == '[':
self.accept()
expr = self.get_values()
elif self.tok in tuple("'tf"):
assert isinstance(self.val, (str, bool))
expr = self.val
self.accept()
else:
raise QAPIParseError(
self, "expected '{', '[', string, or boolean")
return expr
def get_doc(self, info: QAPISourceInfo) -> List['QAPIDoc']:
if self.val != '##':
raise QAPIParseError(
self, "junk after '##' at start of documentation comment")
docs = []
cur_doc = QAPIDoc(self, info)
self.accept(False)
while self.tok == '#':
assert isinstance(self.val, str)
if self.val.startswith('##'):
# End of doc comment
if self.val != '##':
raise QAPIParseError(
self,
"junk after '##' at end of documentation comment")
cur_doc.end_comment()
docs.append(cur_doc)
self.accept()
return docs
if self.val.startswith('# ='):
if cur_doc.symbol:
raise QAPIParseError(
self,
"unexpected '=' markup in definition documentation")
if cur_doc.body.text:
cur_doc.end_comment()
docs.append(cur_doc)
cur_doc = QAPIDoc(self, info)
cur_doc.append(self.val)
self.accept(False)
raise QAPIParseError(self, "documentation comment must end with '##'")
class QAPIDoc:
"""
A documentation comment block, either definition or free-form
Definition documentation blocks consist of
* a body section: one line naming the definition, followed by an
overview (any number of lines)
* argument sections: a description of each argument (for commands
and events) or member (for structs, unions and alternates)
* features sections: a description of each feature flag
* additional (non-argument) sections, possibly tagged
Free-form documentation blocks consist only of a body section.
"""
class Section:
def __init__(self, parser, name=None, indent=0):
# parser, for error messages about indentation
self._parser = parser
# optional section name (argument/member or section name)
self.name = name
self.text = ''
# the expected indent level of the text of this section
self._indent = indent
def append(self, line):
# Strip leading spaces corresponding to the expected indent level
# Blank lines are always OK.
if line:
indent = must_match(r'\s*', line).end()
if indent < self._indent:
raise QAPIParseError(
self._parser,
"unexpected de-indent (expected at least %d spaces)" %
self._indent)
line = line[self._indent:]
self.text += line.rstrip() + '\n'
class ArgSection(Section):
def __init__(self, parser, name, indent=0):
super().__init__(parser, name, indent)
self.member = None
def connect(self, member):
self.member = member
def __init__(self, parser, info):
# self._parser is used to report errors with QAPIParseError. The
# resulting error position depends on the state of the parser.
# It happens to be the beginning of the comment. More or less
# servicable, but action at a distance.
self._parser = parser
self.info = info
self.symbol = None
self.body = QAPIDoc.Section(parser)
# dict mapping parameter name to ArgSection
self.args = OrderedDict()
self.features = OrderedDict()
# a list of Section
self.sections = []
# the current section
self._section = self.body
self._append_line = self._append_body_line
def has_section(self, name):
"""Return True if we have a section with this name."""
for i in self.sections:
if i.name == name:
return True
return False
def append(self, line):
"""
Parse a comment line and add it to the documentation.
The way that the line is dealt with depends on which part of
the documentation we're parsing right now:
* The body section: ._append_line is ._append_body_line
* An argument section: ._append_line is ._append_args_line
* A features section: ._append_line is ._append_features_line
* An additional section: ._append_line is ._append_various_line
"""
line = line[1:]
if not line:
self._append_freeform(line)
return
if line[0] != ' ':
raise QAPIParseError(self._parser, "missing space after #")
line = line[1:]
self._append_line(line)
def end_comment(self):
self._end_section()
@staticmethod
def _is_section_tag(name):
return name in ('Returns:', 'Since:',
# those are often singular or plural
'Note:', 'Notes:',
'Example:', 'Examples:',
'TODO:')
def _append_body_line(self, line):
"""
Process a line of documentation text in the body section.
If this a symbol line and it is the section's first line, this
is a definition documentation block for that symbol.
If it's a definition documentation block, another symbol line
begins the argument section for the argument named by it, and
a section tag begins an additional section. Start that
section and append the line to it.
Else, append the line to the current section.
"""
name = line.split(' ', 1)[0]
# FIXME not nice: things like '# @foo:' and '# @foo: ' aren't
# recognized, and get silently treated as ordinary text
if not self.symbol and not self.body.text and line.startswith('@'):
if not line.endswith(':'):
raise QAPIParseError(self._parser, "line should end with ':'")
self.symbol = line[1:-1]
# FIXME invalid names other than the empty string aren't flagged
if not self.symbol:
raise QAPIParseError(self._parser, "invalid name")
elif self.symbol:
# This is a definition documentation block
if name.startswith('@') and name.endswith(':'):
self._append_line = self._append_args_line
self._append_args_line(line)
elif line == 'Features:':
self._append_line = self._append_features_line
elif self._is_section_tag(name):
self._append_line = self._append_various_line
self._append_various_line(line)
else:
self._append_freeform(line)
else:
# This is a free-form documentation block
self._append_freeform(line)
def _append_args_line(self, line):
"""
Process a line of documentation text in an argument section.
A symbol line begins the next argument section, a section tag
section or a non-indented line after a blank line begins an
additional section. Start that section and append the line to
it.
Else, append the line to the current section.
"""
name = line.split(' ', 1)[0]
if name.startswith('@') and name.endswith(':'):
# If line is "@arg: first line of description", find
# the index of 'f', which is the indent we expect for any
# following lines. We then remove the leading "@arg:"
# from line and replace it with spaces so that 'f' has the
# same index as it did in the original line and can be
# handled the same way we will handle following lines.
indent = must_match(r'@\S*:\s*', line).end()
line = line[indent:]
if not line:
# Line was just the "@arg:" header; following lines
# are not indented
indent = 0
else:
line = ' ' * indent + line
self._start_args_section(name[1:-1], indent)
elif self._is_section_tag(name):
self._append_line = self._append_various_line
self._append_various_line(line)
return
elif (self._section.text.endswith('\n\n')
and line and not line[0].isspace()):
if line == 'Features:':
self._append_line = self._append_features_line
else:
self._start_section()
self._append_line = self._append_various_line
self._append_various_line(line)
return
self._append_freeform(line)
def _append_features_line(self, line):
name = line.split(' ', 1)[0]
if name.startswith('@') and name.endswith(':'):
# If line is "@arg: first line of description", find
# the index of 'f', which is the indent we expect for any
# following lines. We then remove the leading "@arg:"
# from line and replace it with spaces so that 'f' has the
# same index as it did in the original line and can be
# handled the same way we will handle following lines.
indent = must_match(r'@\S*:\s*', line).end()
line = line[indent:]
if not line:
# Line was just the "@arg:" header; following lines
# are not indented
indent = 0
else:
line = ' ' * indent + line
self._start_features_section(name[1:-1], indent)
elif self._is_section_tag(name):
self._append_line = self._append_various_line
self._append_various_line(line)
return
elif (self._section.text.endswith('\n\n')
and line and not line[0].isspace()):
self._start_section()
self._append_line = self._append_various_line
self._append_various_line(line)
return
self._append_freeform(line)
def _append_various_line(self, line):
"""
Process a line of documentation text in an additional section.
A symbol line is an error.
A section tag begins an additional section. Start that
section and append the line to it.
Else, append the line to the current section.
"""
name = line.split(' ', 1)[0]
if name.startswith('@') and name.endswith(':'):
raise QAPIParseError(self._parser,
"'%s' can't follow '%s' section"
% (name, self.sections[0].name))
if self._is_section_tag(name):
# If line is "Section: first line of description", find
# the index of 'f', which is the indent we expect for any
# following lines. We then remove the leading "Section:"
# from line and replace it with spaces so that 'f' has the
# same index as it did in the original line and can be
# handled the same way we will handle following lines.
indent = must_match(r'\S*:\s*', line).end()
line = line[indent:]
if not line:
# Line was just the "Section:" header; following lines
# are not indented
indent = 0
else:
line = ' ' * indent + line
self._start_section(name[:-1], indent)
self._append_freeform(line)
def _start_symbol_section(self, symbols_dict, name, indent):
# FIXME invalid names other than the empty string aren't flagged
if not name:
raise QAPIParseError(self._parser, "invalid parameter name")
if name in symbols_dict:
raise QAPIParseError(self._parser,
"'%s' parameter name duplicated" % name)
assert not self.sections
self._end_section()
self._section = QAPIDoc.ArgSection(self._parser, name, indent)
symbols_dict[name] = self._section
def _start_args_section(self, name, indent):
self._start_symbol_section(self.args, name, indent)
def _start_features_section(self, name, indent):
self._start_symbol_section(self.features, name, indent)
def _start_section(self, name=None, indent=0):
if name in ('Returns', 'Since') and self.has_section(name):
raise QAPIParseError(self._parser,
"duplicated '%s' section" % name)
self._end_section()
self._section = QAPIDoc.Section(self._parser, name, indent)
self.sections.append(self._section)
def _end_section(self):
if self._section:
text = self._section.text = self._section.text.strip()
if self._section.name and (not text or text.isspace()):
raise QAPIParseError(
self._parser,
"empty doc section '%s'" % self._section.name)
self._section = None
def _append_freeform(self, line):
match = re.match(r'(@\S+:)', line)
if match:
raise QAPIParseError(self._parser,
"'%s' not allowed in free-form documentation"
% match.group(1))
self._section.append(line)
def connect_member(self, member):
if member.name not in self.args:
# Undocumented TODO outlaw
self.args[member.name] = QAPIDoc.ArgSection(self._parser,
member.name)
self.args[member.name].connect(member)
def connect_feature(self, feature):
if feature.name not in self.features:
raise QAPISemError(feature.info,
"feature '%s' lacks documentation"
% feature.name)
self.features[feature.name].connect(feature)
def check_expr(self, expr):
if self.has_section('Returns') and 'command' not in expr:
raise QAPISemError(self.info,
"'Returns:' is only valid for commands")
def check(self):
def check_args_section(args, info, what):
bogus = [name for name, section in args.items()
if not section.member]
if bogus:
raise QAPISemError(
self.info,
"documented member%s '%s' %s not exist"
% ("s" if len(bogus) > 1 else "",
"', '".join(bogus),
"do" if len(bogus) > 1 else "does"))
check_args_section(self.args, self.info, 'members')
check_args_section(self.features, self.info, 'features')