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# Copyright 2017-2020 Palantir Technologies, Inc.
# Copyright 2021- Python Language Server Contributors.
import re
import parso
import parso.python.tree as tree_nodes
from pylsp import hookimpl
SKIP_NODES = (tree_nodes.Module, tree_nodes.IfStmt, tree_nodes.TryStmt)
IDENTATION_REGEX = re.compile(r"(\s+).+")
@hookimpl
def pylsp_folding_range(document):
program = document.source + "\n"
lines = program.splitlines()
tree = parso.parse(program)
ranges = __compute_folding_ranges(tree, lines)
results = []
for start_line, end_line in ranges:
start_line -= 1
end_line -= 1
# If start/end character is not defined, then it defaults to the
# corresponding line last character
results.append(
{
"startLine": start_line,
"endLine": end_line,
}
)
return results
def __merge_folding_ranges(left, right):
for start in list(left.keys()):
right_start = right.pop(start, None)
if right_start is not None:
left[start] = max(right_start, start)
left.update(right)
return left
def __empty_identation_stack(
identation_stack, level_limits, current_line, folding_ranges
):
while identation_stack != []:
upper_level = identation_stack.pop(0)
level_start = level_limits.pop(upper_level)
folding_ranges.append((level_start, current_line))
return folding_ranges
def __match_identation_stack(
identation_stack, level, level_limits, folding_ranges, current_line
):
upper_level = identation_stack.pop(0)
while upper_level >= level:
level_start = level_limits.pop(upper_level)
folding_ranges.append((level_start, current_line))
upper_level = identation_stack.pop(0)
identation_stack.insert(0, upper_level)
return identation_stack, folding_ranges
def __compute_folding_ranges_identation(text):
lines = text.splitlines()
folding_ranges = []
identation_stack = []
level_limits = {}
current_level = 0
current_line = 0
while lines[current_line] == "":
current_line += 1
for i, line in enumerate(lines):
if i < current_line:
continue
i += 1
identation_match = IDENTATION_REGEX.match(line)
if identation_match is not None:
whitespace = identation_match.group(1)
level = len(whitespace)
if level > current_level:
level_limits[current_level] = current_line
identation_stack.insert(0, current_level)
current_level = level
elif level < current_level:
identation_stack, folding_ranges = __match_identation_stack(
identation_stack, level, level_limits, folding_ranges, current_line
)
current_level = level
else:
folding_ranges = __empty_identation_stack(
identation_stack, level_limits, current_line, folding_ranges
)
current_level = 0
if line.strip() != "":
current_line = i
folding_ranges = __empty_identation_stack(
identation_stack, level_limits, current_line, folding_ranges
)
return dict(folding_ranges)
def __check_if_node_is_valid(node):
valid = True
if isinstance(node, tree_nodes.PythonNode):
kind = node.type
valid = kind not in {
"decorated",
"parameters",
"dictorsetmaker",
"testlist_comp",
}
if kind == "suite":
if isinstance(node.parent, tree_nodes.Function):
valid = False
return valid
def __handle_skip(stack, skip):
body = stack[skip]
children = [body]
if hasattr(body, "children"):
children = body.children
stack = stack[:skip] + children + stack[skip + 1 :]
node = body
end_line, _ = body.end_pos
return node, end_line
def __handle_flow_nodes(node, end_line, stack):
from_keyword = False
if isinstance(node, tree_nodes.Keyword):
from_keyword = True
if node.value in {"if", "elif", "with", "while"}:
node, end_line = __handle_skip(stack, 2)
elif node.value in {"except"}:
first_node = stack[0]
if isinstance(first_node, tree_nodes.Operator):
node, end_line = __handle_skip(stack, 1)
else:
node, end_line = __handle_skip(stack, 2)
elif node.value in {"for"}:
node, end_line = __handle_skip(stack, 4)
elif node.value in {"else"}:
node, end_line = __handle_skip(stack, 1)
return end_line, from_keyword, node, stack
def __compute_start_end_lines(node, stack):
start_line, _ = node.start_pos
end_line, _ = node.end_pos
modified = False
end_line, from_keyword, node, stack = __handle_flow_nodes(node, end_line, stack)
last_leaf = node.get_last_leaf()
last_newline = isinstance(last_leaf, tree_nodes.Newline)
last_operator = isinstance(last_leaf, tree_nodes.Operator)
node_is_operator = isinstance(node, tree_nodes.Operator)
last_operator = last_operator or not node_is_operator
end_line -= 1
if isinstance(node.parent, tree_nodes.PythonNode) and not from_keyword:
kind = node.type
if kind in {"suite", "atom", "atom_expr", "arglist"}:
if len(stack) > 0:
next_node = stack[0]
next_line, _ = next_node.start_pos
if next_line > end_line:
end_line += 1
modified = True
if not last_newline and not modified and not last_operator:
end_line += 1
return start_line, end_line, stack
def __compute_folding_ranges(tree, lines):
folding_ranges = {}
stack = [tree]
while len(stack) > 0:
node = stack.pop(0)
if isinstance(node, tree_nodes.Newline):
# Skip newline nodes
continue
if isinstance(node, tree_nodes.PythonErrorNode):
# Fallback to indentation-based (best-effort) folding
start_line, _ = node.start_pos
start_line -= 1
padding = [""] * start_line
text = "\n".join(padding + lines[start_line:]) + "\n"
identation_ranges = __compute_folding_ranges_identation(text)
folding_ranges = __merge_folding_ranges(folding_ranges, identation_ranges)
break
if not isinstance(node, SKIP_NODES):
valid = __check_if_node_is_valid(node)
if valid:
start_line, end_line, stack = __compute_start_end_lines(node, stack)
if end_line > start_line:
current_end = folding_ranges.get(start_line, -1)
folding_ranges[start_line] = max(current_end, end_line)
if hasattr(node, "children"):
stack = node.children + stack
folding_ranges = sorted(folding_ranges.items())
return folding_ranges
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