Index: reviewbot/handlers/policy_checklist/parser.py |
=================================================================== |
--- reviewbot/handlers/policy_checklist/parser.py (revision 0) |
+++ reviewbot/handlers/policy_checklist/parser.py (revision 0) |
@@ -0,0 +1,174 @@ |
+# Copyright (c) 2013 The Chromium Authors. All rights reserved. |
+# Use of this source code is governed by a BSD-style license that can be |
+# found in the LICENSE file. |
+ |
+import re |
+ |
+import util |
+ |
+ |
+CONTEXT_THRESHOLD = 12 |
+PROPERTY_NAME_RE = re.compile(r"^\s*'(\w+)'\s*:") |
+ |
+ |
+def nmin(*args): |
+ """Calculates the minimum of |args|, ignoring None entries.""" |
+ values = [v for v in args if v is not None] |
+ return None if len(values) == 0 else min(values) |
+ |
+ |
+def nmax(*args): |
+ """Calculates the maximum of |args|, ignoring None entries.""" |
+ values = [v for v in args if v is not None] |
+ return None if len(values) == 0 else max(values) |
+ |
+ |
+def nadd(a, b): |
+ """Calculates a + b, returning None if either a or b is None""" |
+ return None if (a is None or b is None) else a + b |
+ |
+ |
+def nsub(a, b): |
+ """Calculates a - b, returning None if either a or b is None""" |
+ return None if (a is None or b is None) else a - b |
+ |
+ |
+def get_indentation_level(line): |
+ """Returns the indentation level (number of leading spaces) for |line|.""" |
+ nspaces = len(line) - len(line.lstrip(' ')) |
+ return None if nspaces == 0 else nspaces |
+ |
+ |
+class PolicyChangeParser(object): |
+ """Parses a policy_templates.json diff to identify logical changes. |
+ |
+ This takes a list of triples of the form (old_line, new_line, text) as |
+ returned by patching.ParsePatchToLines and produces a list of dictionaries |
+ describing the logical changes that have been made. The dictionaries contain |
+ these keys: |
+ * start: A pair (old_line, new_line) indicating where the change starts. |
+ * end: A pair (old_line, new_line) indicating where the change ends. |
+ * comment_pos: A pair (old_line, new_line), indicating a suitable place to |
+ put an inline comment. This is typically the line where the |
+ policy name is found in the diff. |
+ * additions: Whether there have been line additions. |
+ * removals: Whether there have been line removals. |
+ """ |
+ |
+ def __init__(self, lines): |
+ self.lines = lines |
+ self.chunks_list = [] |
+ self.reset() |
+ |
+ def run(self): |
+ """Main parsing function. |
+ |
+ The code goes over the diff line by line, keeping track of the current line. |
+ It keeps track of the current line numbers, and where the last changes |
+ happened in the old and new version of the file. |
+ |
+ Certain events trigger start of a new logical change. These are |
+ discontinuities in the cursor position and decreases of the indentation |
+ level. Once a block closes, the information for that block is recorded in |
+ the result list. |
+ """ |
+ self.chunks_list = [] |
+ self.last_change = [None, None] |
+ cursor = [None, None] |
+ self.reset() |
+ for (a_line, b_line, line) in self.lines: |
+ # Skip comment lines. |
+ if line.startswith('#'): |
+ continue |
+ |
+ # See whether the current line has a JSON property. |
+ keyword = None |
+ match = PROPERTY_NAME_RE.match(line) |
+ if match: |
+ keyword = match.group(1).lower() |
+ |
+ |
+ # Check whether the current block closes. |
+ line_indent = get_indentation_level(line) |
+ if (self.block_indent is not None and |
+ line_indent is not None and |
+ line_indent < self.block_indent): |
+ self.block_closed = True |
+ |
+ # Update various cursors. |
+ cursor = [nmax(a_line, cursor[0]), nmax(b_line, cursor[1])] |
+ offset = nmin(nsub(cursor[0], self.last_change[0]), |
+ nsub(cursor[1], self.last_change[1])) |
+ |
+ # Update change tracking state. |
+ if a_line is not None and b_line is None: |
+ self.removals = True |
+ self.last_change[0] = a_line |
+ self.text_changed |= any([c.isalnum() for c in line]) |
+ elif a_line is None and b_line is not None: |
+ self.additions = True |
+ self.last_change[1] = b_line |
+ self.text_changed |= any([c.isalnum() for c in line]) |
+ |
+ # If the indentation block closes or the last chunk is too far away, |
+ # assume a new one starts. |
+ if (self.block_closed or |
+ (offset is not None and (offset > CONTEXT_THRESHOLD))): |
+ self.flush_chunk() |
+ |
+ # Try to figure out block indent from properties exclusively used for |
+ # policy definitions. |
+ if (self.block_indent is None and |
+ keyword in ('id', 'schema', 'future', 'features', 'supported_on', |
+ 'example_value', 'deprecated')): |
+ self.block_indent = line_indent |
+ |
+ # Put the comment on the policy name property if we see it fly by. |
+ if keyword == 'name': |
+ # Filter out name labels on enum items and schemas. |
+ if self.block_indent is not None and self.block_indent != line_indent: |
+ pass |
+ elif a_line is not None and b_line is None: |
+ self.comment_pos[0] = a_line |
+ elif a_line is None and b_line is not None: |
+ self.comment_pos[1] = b_line |
+ |
+ self.chunk_start = [nmin(self.last_change[0], self.chunk_start[0]), |
+ nmin(self.last_change[1], self.chunk_start[1])] |
+ |
+ # Flush the last chunk. |
+ if self.chunk_start != [None, None]: |
+ self.flush_chunk() |
+ |
+ def flush_chunk(self): |
+ if self.text_changed: |
+ comment_pos = [nmax(self.chunk_start[0], self.comment_pos[0]), |
+ nmax(self.chunk_start[1], self.comment_pos[1])] |
+ self.chunks_list.append( |
+ util.ObjectDict( |
+ { 'start': self.chunk_start, |
+ 'end': [nadd(self.last_change[0], 1), |
+ nadd(self.last_change[1], 1)], |
+ 'comment_pos': comment_pos, |
+ 'additions': self.additions, |
+ 'removals': self.removals })) |
+ self.reset() |
+ |
+ def reset(self): |
+ # This is called from __init__. |
+ # pylint: disable=W0201 |
+ self.chunk_start = [None, None] |
+ self.last_change = [None, None] |
+ self.comment_pos = [None, None] |
+ self.block_indent = None |
+ self.block_closed = False |
+ self.additions = False |
+ self.removals = False |
+ self.text_changed = False |
+ |
+ |
+def parse(lines): |
+ """Helper function to parse lines to a list of chunks directly.""" |
+ parser = PolicyChangeParser(lines) |
+ parser.run() |
+ return parser.chunks_list |
Property changes on: reviewbot/handlers/policy_checklist/parser.py |
___________________________________________________________________ |
Added: svn:eol-style |
+ LF |