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| 1 | +# pylint: disable=len-as-condition |
| 2 | +# Copyright 2019 Palantir Technologies, Inc. |
| 3 | + |
| 4 | +import re |
| 5 | + |
| 6 | +import parso |
| 7 | +import parso.python.tree as tree_nodes |
| 8 | + |
| 9 | +from pyls import hookimpl |
| 10 | + |
| 11 | +SKIP_NODES = (tree_nodes.Module, tree_nodes.IfStmt, tree_nodes.TryStmt) |
| 12 | +IDENTATION_REGEX = re.compile(r'(\s+).+') |
| 13 | + |
| 14 | + |
| 15 | +@hookimpl |
| 16 | +def pyls_folding_range(document): |
| 17 | + program = document.source + '\n' |
| 18 | + lines = program.splitlines() |
| 19 | + tree = parso.parse(program) |
| 20 | + ranges = __compute_folding_ranges(tree, lines) |
| 21 | + |
| 22 | + results = [] |
| 23 | + for (start_line, end_line) in ranges: |
| 24 | + start_line -= 1 |
| 25 | + end_line -= 1 |
| 26 | + # If start/end character is not defined, then it defaults to the |
| 27 | + # corresponding line last character |
| 28 | + results.append({ |
| 29 | + 'startLine': start_line, |
| 30 | + 'endLine': end_line, |
| 31 | + }) |
| 32 | + return results |
| 33 | + |
| 34 | + |
| 35 | +def __merge_folding_ranges(left, right): |
| 36 | + for start in list(left.keys()): |
| 37 | + right_start = right.pop(start, None) |
| 38 | + if right_start is not None: |
| 39 | + left[start] = max(right_start, start) |
| 40 | + left.update(right) |
| 41 | + return left |
| 42 | + |
| 43 | + |
| 44 | +def __empty_identation_stack(identation_stack, level_limits, |
| 45 | + current_line, folding_ranges): |
| 46 | + while identation_stack != []: |
| 47 | + upper_level = identation_stack.pop(0) |
| 48 | + level_start = level_limits.pop(upper_level) |
| 49 | + folding_ranges.append((level_start, current_line)) |
| 50 | + return folding_ranges |
| 51 | + |
| 52 | + |
| 53 | +def __match_identation_stack(identation_stack, level, level_limits, |
| 54 | + folding_ranges, current_line): |
| 55 | + upper_level = identation_stack.pop(0) |
| 56 | + while upper_level >= level: |
| 57 | + level_start = level_limits.pop(upper_level) |
| 58 | + folding_ranges.append((level_start, current_line)) |
| 59 | + upper_level = identation_stack.pop(0) |
| 60 | + identation_stack.insert(0, upper_level) |
| 61 | + return identation_stack, folding_ranges |
| 62 | + |
| 63 | + |
| 64 | +def __compute_folding_ranges_identation(text): |
| 65 | + lines = text.splitlines() |
| 66 | + folding_ranges = [] |
| 67 | + identation_stack = [] |
| 68 | + level_limits = {} |
| 69 | + current_level = 0 |
| 70 | + current_line = 0 |
| 71 | + while lines[current_line] == '': |
| 72 | + current_line += 1 |
| 73 | + for i, line in enumerate(lines): |
| 74 | + if i < current_line: |
| 75 | + continue |
| 76 | + i += 1 |
| 77 | + identation_match = IDENTATION_REGEX.match(line) |
| 78 | + if identation_match is not None: |
| 79 | + whitespace = identation_match.group(1) |
| 80 | + level = len(whitespace) |
| 81 | + if level > current_level: |
| 82 | + level_limits[current_level] = current_line |
| 83 | + identation_stack.insert(0, current_level) |
| 84 | + current_level = level |
| 85 | + elif level < current_level: |
| 86 | + identation_stack, folding_ranges = __match_identation_stack( |
| 87 | + identation_stack, level, level_limits, folding_ranges, |
| 88 | + current_line) |
| 89 | + current_level = level |
| 90 | + else: |
| 91 | + folding_ranges = __empty_identation_stack( |
| 92 | + identation_stack, level_limits, current_line, folding_ranges) |
| 93 | + current_level = 0 |
| 94 | + if line.strip() != '': |
| 95 | + current_line = i |
| 96 | + folding_ranges = __empty_identation_stack( |
| 97 | + identation_stack, level_limits, current_line, folding_ranges) |
| 98 | + return dict(folding_ranges) |
| 99 | + |
| 100 | + |
| 101 | +def __check_if_node_is_valid(node): |
| 102 | + valid = True |
| 103 | + if isinstance(node, tree_nodes.PythonNode): |
| 104 | + kind = node.type |
| 105 | + valid = kind not in {'decorated', 'parameters'} |
| 106 | + if kind == 'suite': |
| 107 | + if isinstance(node.parent, tree_nodes.Function): |
| 108 | + valid = False |
| 109 | + return valid |
| 110 | + |
| 111 | + |
| 112 | +def __compute_start_end_lines(node, stack): |
| 113 | + start_line, _ = node.start_pos |
| 114 | + end_line, _ = node.end_pos |
| 115 | + |
| 116 | + last_leaf = node.get_last_leaf() |
| 117 | + last_newline = isinstance(last_leaf, tree_nodes.Newline) |
| 118 | + last_operator = isinstance(last_leaf, tree_nodes.Operator) |
| 119 | + node_is_operator = isinstance(node, tree_nodes.Operator) |
| 120 | + last_operator = last_operator or not node_is_operator |
| 121 | + |
| 122 | + end_line -= 1 |
| 123 | + |
| 124 | + modified = False |
| 125 | + if isinstance(node.parent, tree_nodes.PythonNode): |
| 126 | + kind = node.type |
| 127 | + if kind in {'suite', 'atom', 'atom_expr', 'arglist'}: |
| 128 | + if len(stack) > 0: |
| 129 | + next_node = stack[0] |
| 130 | + next_line, _ = next_node.start_pos |
| 131 | + if next_line > end_line: |
| 132 | + end_line += 1 |
| 133 | + modified = True |
| 134 | + if not last_newline and not modified and not last_operator: |
| 135 | + end_line += 1 |
| 136 | + return start_line, end_line |
| 137 | + |
| 138 | + |
| 139 | +def __compute_folding_ranges(tree, lines): |
| 140 | + folding_ranges = {} |
| 141 | + stack = [tree] |
| 142 | + |
| 143 | + while len(stack) > 0: |
| 144 | + node = stack.pop(0) |
| 145 | + if isinstance(node, tree_nodes.Newline): |
| 146 | + # Skip newline nodes |
| 147 | + continue |
| 148 | + elif isinstance(node, tree_nodes.PythonErrorNode): |
| 149 | + # Fallback to identation-based (best-effort) folding |
| 150 | + start_line, _ = node.start_pos |
| 151 | + start_line -= 1 |
| 152 | + padding = [''] * start_line |
| 153 | + text = '\n'.join(padding + lines[start_line:]) + '\n' |
| 154 | + identation_ranges = __compute_folding_ranges_identation(text) |
| 155 | + folding_ranges = __merge_folding_ranges( |
| 156 | + folding_ranges, identation_ranges) |
| 157 | + break |
| 158 | + elif not isinstance(node, SKIP_NODES): |
| 159 | + valid = __check_if_node_is_valid(node) |
| 160 | + if valid: |
| 161 | + start_line, end_line = __compute_start_end_lines(node, stack) |
| 162 | + if end_line > start_line: |
| 163 | + current_end = folding_ranges.get(start_line, -1) |
| 164 | + folding_ranges[start_line] = max(current_end, end_line) |
| 165 | + if hasattr(node, 'children'): |
| 166 | + stack = node.children + stack |
| 167 | + |
| 168 | + folding_ranges = sorted(folding_ranges.items()) |
| 169 | + return folding_ranges |
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