vscode-python/pythonFiles/parso/python/diff.py at master · charismafight/vscode-python · GitHub

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"""

Basically a contains parser that is faster, because it tries to parse only

parts and if anything changes, it only reparses the changed parts.

It works with a simple diff in the beginning and will try to reuse old parser

fragments.

"""

import re

import difflib

from collections import namedtuple

import logging

from parso.utils import split_lines

from parso.python.parser import Parser

from parso.python.tree import EndMarker

from parso.python.tokenize import (NEWLINE, PythonToken, ERROR_DEDENT,

ENDMARKER, INDENT, DEDENT)

LOG = logging.getLogger(__name__)

def _get_last_line(node_or_leaf):

last_leaf = node_or_leaf.get_last_leaf()

if _ends_with_newline(last_leaf):

return last_leaf.start_pos[0]

else:

return last_leaf.end_pos[0]

def _ends_with_newline(leaf, suffix=''):

if leaf.type == 'error_leaf':

typ = leaf.original_type

else:

typ = leaf.type

return typ == 'newline' or suffix.endswith('\n')

def _flows_finished(pgen_grammar, stack):

"""

if, while, for and try might not be finished, because another part might

still be parsed.

"""

for dfa, newstate, (symbol_number, nodes) in stack:

if pgen_grammar.number2symbol[symbol_number] in ('if_stmt', 'while_stmt',

'for_stmt', 'try_stmt'):

return False

return True

def suite_or_file_input_is_valid(pgen_grammar, stack):

if not _flows_finished(pgen_grammar, stack):

return False

for dfa, newstate, (symbol_number, nodes) in reversed(stack):

if pgen_grammar.number2symbol[symbol_number] == 'suite':

# If only newline is in the suite, the suite is not valid, yet.

return len(nodes) > 1

# Not reaching a suite means that we're dealing with file_input levels

# where there's no need for a valid statement in it. It can also be empty.

return True

def _is_flow_node(node):

try:

value = node.children[0].value

except AttributeError:

return False

return value in ('if', 'for', 'while', 'try')

class _PositionUpdatingFinished(Exception):

pass

def _update_positions(nodes, line_offset, last_leaf):

for node in nodes:

try:

children = node.children

except AttributeError:

# Is a leaf

node.line += line_offset

if node is last_leaf:

raise _PositionUpdatingFinished

else:

_update_positions(children, line_offset, last_leaf)

class DiffParser(object):

"""

An advanced form of parsing a file faster. Unfortunately comes with huge

side effects. It changes the given module.

"""

def __init__(self, pgen_grammar, tokenizer, module):

self._pgen_grammar = pgen_grammar

self._tokenizer = tokenizer

self._module = module

def _reset(self):

self._copy_count = 0

self._parser_count = 0

self._nodes_stack = _NodesStack(self._module)

def update(self, old_lines, new_lines):

'''

The algorithm works as follows:

Equal:

- Assure that the start is a newline, otherwise parse until we get

one.

- Copy from parsed_until_line + 1 to max(i2 + 1)

- Make sure that the indentation is correct (e.g. add DEDENT)

- Add old and change positions

Insert:

- Parse from parsed_until_line + 1 to min(j2 + 1), hopefully not

much more.

Returns the new module node.

'''

LOG.debug('diff parser start')

# Reset the used names cache so they get regenerated.

self._module._used_names = None

self._parser_lines_new = new_lines

self._reset()

line_length = len(new_lines)

sm = difflib.SequenceMatcher(None, old_lines, self._parser_lines_new)

opcodes = sm.get_opcodes()

LOG.debug('diff parser calculated')

LOG.debug('diff: line_lengths old: %s, new: %s' % (len(old_lines), line_length))

for operation, i1, i2, j1, j2 in opcodes:

LOG.debug('diff %s old[%s:%s] new[%s:%s]',

operation, i1 + 1, i2, j1 + 1, j2)

if j2 == line_length and new_lines[-1] == '':

# The empty part after the last newline is not relevant.

j2 -= 1

if operation == 'equal':

line_offset = j1 - i1

self._copy_from_old_parser(line_offset, i2, j2)

elif operation == 'replace':

self._parse(until_line=j2)

elif operation == 'insert':

self._parse(until_line=j2)

else:

assert operation == 'delete'

# With this action all change will finally be applied and we have a

# changed module.

self._nodes_stack.close()

last_pos = self._module.end_pos[0]

if last_pos != line_length:

current_lines = split_lines(self._module.get_code(), keepends=True)

diff = difflib.unified_diff(current_lines, new_lines)

raise Exception(

"There's an issue (%s != %s) with the diff parser. Please report:\n%s"

% (last_pos, line_length, ''.join(diff))

)

LOG.debug('diff parser end')

return self._module

def _enabled_debugging(self, old_lines, lines_new):

if self._module.get_code() != ''.join(lines_new):

LOG.warning('parser issue:\n%s\n%s', ''.join(old_lines),

''.join(lines_new))

def _copy_from_old_parser(self, line_offset, until_line_old, until_line_new):

copied_nodes = [None]

last_until_line = -1

while until_line_new > self._nodes_stack.parsed_until_line:

parsed_until_line_old = self._nodes_stack.parsed_until_line - line_offset

line_stmt = self._get_old_line_stmt(parsed_until_line_old + 1)

if line_stmt is None:

# Parse 1 line at least. We don't need more, because we just

# want to get into a state where the old parser has statements

# again that can be copied (e.g. not lines within parentheses).

self._parse(self._nodes_stack.parsed_until_line + 1)

elif not copied_nodes:

# We have copied as much as possible (but definitely not too

# much). Therefore we just parse the rest.

# We might not reach the end, because there's a statement

# that is not finished.

self._parse(until_line_new)

else:

p_children = line_stmt.parent.children

index = p_children.index(line_stmt)

copied_nodes = self._nodes_stack.copy_nodes(

p_children[index:],

until_line_old,

line_offset

)

# Match all the nodes that are in the wanted range.

if copied_nodes:

self._copy_count += 1

from_ = copied_nodes[0].get_start_pos_of_prefix()[0] + line_offset

to = self._nodes_stack.parsed_until_line

LOG.debug('diff actually copy %s to %s', from_, to)

# Since there are potential bugs that might loop here endlessly, we

# just stop here.

assert last_until_line != self._nodes_stack.parsed_until_line \

or not copied_nodes, last_until_line

last_until_line = self._nodes_stack.parsed_until_line

def _get_old_line_stmt(self, old_line):

leaf = self._module.get_leaf_for_position((old_line, 0), include_prefixes=True)

if _ends_with_newline(leaf):

leaf = leaf.get_next_leaf()

if leaf.get_start_pos_of_prefix()[0] == old_line:

node = leaf

while node.parent.type not in ('file_input', 'suite'):

node = node.parent

return node

# Must be on the same line. Otherwise we need to parse that bit.

return None

def _get_before_insertion_node(self):

if self._nodes_stack.is_empty():

return None

line = self._nodes_stack.parsed_until_line + 1

node = self._new_module.get_last_leaf()

while True:

parent = node.parent

if parent.type in ('suite', 'file_input'):

assert node.end_pos[0] <= line

assert node.end_pos[1] == 0 or '\n' in self._prefix

return node

node = parent

def _parse(self, until_line):

"""

Parses at least until the given line, but might just parse more until a

valid state is reached.

"""

last_until_line = 0

while until_line > self._nodes_stack.parsed_until_line:

node = self._try_parse_part(until_line)

nodes = node.children

self._nodes_stack.add_parsed_nodes(nodes)

LOG.debug(

'parse_part from %s to %s (to %s in part parser)',

nodes[0].get_start_pos_of_prefix()[0],

self._nodes_stack.parsed_until_line,

node.end_pos[0] - 1

)

# Since the tokenizer sometimes has bugs, we cannot be sure that

# this loop terminates. Therefore assert that there's always a

# change.

assert last_until_line != self._nodes_stack.parsed_until_line, last_until_line

last_until_line = self._nodes_stack.parsed_until_line

def _try_parse_part(self, until_line):

"""

Sets up a normal parser that uses a spezialized tokenizer to only parse

until a certain position (or a bit longer if the statement hasn't

ended.

"""

self._parser_count += 1

# TODO speed up, shouldn't copy the whole list all the time.

# memoryview?

parsed_until_line = self._nodes_stack.parsed_until_line

lines_after = self._parser_lines_new[parsed_until_line:]

#print('parse_content', parsed_until_line, lines_after, until_line)

tokens = self._diff_tokenize(

lines_after,

until_line,

line_offset=parsed_until_line

)

self._active_parser = Parser(

self._pgen_grammar,

error_recovery=True

)

return self._active_parser.parse(tokens=tokens)

def _diff_tokenize(self, lines, until_line, line_offset=0):

is_first_token = True

omitted_first_indent = False

indents = []

tokens = self._tokenizer(lines, (1, 0))

stack = self._active_parser.pgen_parser.stack

for typ, string, start_pos, prefix in tokens:

start_pos = start_pos[0] + line_offset, start_pos[1]

if typ == INDENT:

indents.append(start_pos[1])

if is_first_token:

omitted_first_indent = True

# We want to get rid of indents that are only here because

# we only parse part of the file. These indents would only

# get parsed as error leafs, which doesn't make any sense.

is_first_token = False

continue

is_first_token = False

# In case of omitted_first_indent, it might not be dedented fully.

# However this is a sign for us that a dedent happened.

if typ == DEDENT \

or typ == ERROR_DEDENT and omitted_first_indent and len(indents) == 1:

indents.pop()

if omitted_first_indent and not indents:

# We are done here, only thing that can come now is an

# endmarker or another dedented code block.

typ, string, start_pos, prefix = next(tokens)

if '\n' in prefix:

prefix = re.sub(r'(<=\n)[^\n]+$', '', prefix)

else:

prefix = ''

yield PythonToken(ENDMARKER, '', (start_pos[0] + line_offset, 0), prefix)

break

elif typ == NEWLINE and start_pos[0] >= until_line:

yield PythonToken(typ, string, start_pos, prefix)

# Check if the parser is actually in a valid suite state.

if suite_or_file_input_is_valid(self._pgen_grammar, stack):

start_pos = start_pos[0] + 1, 0

while len(indents) > int(omitted_first_indent):

indents.pop()

yield PythonToken(DEDENT, '', start_pos, '')

yield PythonToken(ENDMARKER, '', start_pos, '')

break

else:

continue

yield PythonToken(typ, string, start_pos, prefix)

class _NodesStackNode(object):

ChildrenGroup = namedtuple('ChildrenGroup', 'children line_offset last_line_offset_leaf')

def __init__(self, tree_node, parent=None):

self.tree_node = tree_node

self.children_groups = []

self.parent = parent

def close(self):

children = []

for children_part, line_offset, last_line_offset_leaf in self.children_groups:

if line_offset != 0:

try:

_update_positions(

children_part, line_offset, last_line_offset_leaf)

except _PositionUpdatingFinished:

pass

children += children_part

self.tree_node.children = children

# Reset the parents

for node in children:

node.parent = self.tree_node

def add(self, children, line_offset=0, last_line_offset_leaf=None):

group = self.ChildrenGroup(children, line_offset, last_line_offset_leaf)

self.children_groups.append(group)

def get_last_line(self, suffix):

line = 0

if self.children_groups:

children_group = self.children_groups[-1]

last_leaf = children_group.children[-1].get_last_leaf()

line = last_leaf.end_pos[0]

# Calculate the line offsets

offset = children_group.line_offset

if offset:

# In case the line_offset is not applied to this specific leaf,

# just ignore it.

if last_leaf.line <= children_group.last_line_offset_leaf.line:

line += children_group.line_offset

# Newlines end on the next line, which means that they would cover

# the next line. That line is not fully parsed at this point.

if _ends_with_newline(last_leaf, suffix):

line -= 1

line += suffix.count('\n')

if suffix and not suffix.endswith('\n'):

# This is the end of a file (that doesn't end with a newline).

line += 1

return line

class _NodesStack(object):

endmarker_type = 'endmarker'

def __init__(self, module):

# Top of stack

self._tos = self._base_node = _NodesStackNode(module)

self._module = module

self._last_prefix = ''

self.prefix = ''

def is_empty(self):

return not self._base_node.children

@property

def parsed_until_line(self):

return self._tos.get_last_line(self.prefix)

def _get_insertion_node(self, indentation_node):

indentation = indentation_node.start_pos[1]

# find insertion node

node = self._tos

while True:

tree_node = node.tree_node

if tree_node.type == 'suite':

# A suite starts with NEWLINE, ...

node_indentation = tree_node.children[1].start_pos[1]

if indentation >= node_indentation: # Not a Dedent

# We might be at the most outer layer: modules. We

# don't want to depend on the first statement

# having the right indentation.

return node

elif tree_node.type == 'file_input':

return node

node = self._close_tos()

def _close_tos(self):

self._tos.close()

self._tos = self._tos.parent

return self._tos

def add_parsed_nodes(self, tree_nodes):

tree_nodes = self._remove_endmarker(tree_nodes)

if not tree_nodes:

return

assert tree_nodes[0].type != 'newline'

node = self._get_insertion_node(tree_nodes[0])

assert node.tree_node.type in ('suite', 'file_input')

node.add(tree_nodes)

self._update_tos(tree_nodes[-1])

def _remove_endmarker(self, tree_nodes):

"""

Helps cleaning up the tree nodes that get inserted.

"""

last_leaf = tree_nodes[-1].get_last_leaf()

is_endmarker = last_leaf.type == self.endmarker_type

self._last_prefix = ''

if is_endmarker:

try:

separation = last_leaf.prefix.rindex('\n')

except ValueError:

pass

else:

# Remove the whitespace part of the prefix after a newline.

# That is not relevant if parentheses were opened. Always parse

# until the end of a line.

last_leaf.prefix, self._last_prefix = \

last_leaf.prefix[:separation + 1], last_leaf.prefix[separation + 1:]

first_leaf = tree_nodes[0].get_first_leaf()

first_leaf.prefix = self.prefix + first_leaf.prefix

self.prefix = ''

if is_endmarker:

self.prefix = last_leaf.prefix

tree_nodes = tree_nodes[:-1]

return tree_nodes

def copy_nodes(self, tree_nodes, until_line, line_offset):

"""

Copies tree nodes from the old parser tree.

Returns the number of tree nodes that were copied.

"""

tos = self._get_insertion_node(tree_nodes[0])

new_nodes, self._tos = self._copy_nodes(tos, tree_nodes, until_line, line_offset)

return new_nodes

def _copy_nodes(self, tos, nodes, until_line, line_offset):

new_nodes = []

new_tos = tos

for node in nodes:

if node.type == 'endmarker':

# Endmarkers just distort all the checks below. Remove them.

break

if node.start_pos[0] > until_line:

break

# TODO this check might take a bit of time for large files. We

# might want to change this to do more intelligent guessing or

# binary search.

if _get_last_line(node) > until_line:

# We can split up functions and classes later.

if node.type in ('classdef', 'funcdef') and node.children[-1].type == 'suite':

new_nodes.append(node)

break

new_nodes.append(node)

if not new_nodes:

return [], tos

last_node = new_nodes[-1]

line_offset_index = -1

if last_node.type in ('classdef', 'funcdef'):

suite = last_node.children[-1]

if suite.type == 'suite':

suite_tos = _NodesStackNode(suite)

# Don't need to pass line_offset here, it's already done by the

# parent.

suite_nodes, recursive_tos = self._copy_nodes(

suite_tos, suite.children, until_line, line_offset)

if len(suite_nodes) < 2:

# A suite only with newline is not valid.

new_nodes.pop()

else:

suite_tos.parent = tos

new_tos = recursive_tos

line_offset_index = -2

elif (new_nodes[-1].type in ('error_leaf', 'error_node') or

_is_flow_node(new_nodes[-1])):

# Error leafs/nodes don't have a defined start/end. Error

# nodes might not end with a newline (e.g. if there's an

# open `(`). Therefore ignore all of them unless they are

# succeeded with valid parser state.

# If we copy flows at the end, they might be continued

# after the copy limit (in the new parser).

# In this while loop we try to remove until we find a newline.

new_nodes.pop()

while new_nodes:

last_node = new_nodes[-1]

if last_node.get_last_leaf().type == 'newline':

break

new_nodes.pop()

if new_nodes:

try:

last_line_offset_leaf = new_nodes[line_offset_index].get_last_leaf()

except IndexError:

line_offset = 0

# In this case we don't have to calculate an offset, because

# there's no children to be managed.

last_line_offset_leaf = None

tos.add(new_nodes, line_offset, last_line_offset_leaf)

return new_nodes, new_tos

def _update_tos(self, tree_node):

if tree_node.type in ('suite', 'file_input'):

self._tos = _NodesStackNode(tree_node, self._tos)

self._tos.add(list(tree_node.children))

self._update_tos(tree_node.children[-1])

elif tree_node.type in ('classdef', 'funcdef'):

self._update_tos(tree_node.children[-1])

def close(self):

while self._tos is not None:

self._close_tos()

# Add an endmarker.

try:

last_leaf = self._module.get_last_leaf()

end_pos = list(last_leaf.end_pos)

except IndexError:

end_pos = [1, 0]

lines = split_lines(self.prefix)

assert len(lines) > 0

if len(lines) == 1:

end_pos[1] += len(lines[0])

else:

end_pos[0] += len(lines) - 1

end_pos[1] = len(lines[-1])

endmarker = EndMarker('', tuple(end_pos), self.prefix + self._last_prefix)

endmarker.parent = self._module

self._module.children.append(endmarker)

vscode-python/pythonFiles/parso/python/diff.py at master · charismafight/vscode-python · GitHub

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