Example of refactoring using rope library.

tools/telemetry/third_party/rope/rope/contrib/fixsyntax.py

Index: tools/telemetry/third_party/rope/rope/contrib/fixsyntax.py
diff --git a/tools/telemetry/third_party/rope/rope/contrib/fixsyntax.py b/tools/telemetry/third_party/rope/rope/contrib/fixsyntax.py
new file mode 100644
index 0000000000000000000000000000000000000000..cc45ad19b3458a3a0cacfad11492dac828e32312
--- /dev/null
+++ b/tools/telemetry/third_party/rope/rope/contrib/fixsyntax.py
@@ -0,0 +1,181 @@
+import rope.base.codeanalyze
+import rope.base.evaluate
+from rope.base import exceptions
+from rope.base import libutils
+from rope.base import utils
+from rope.base import worder
+from rope.base.codeanalyze import ArrayLinesAdapter, LogicalLineFinder
+
+
+class FixSyntax(object):
+
+    def __init__(self, project, code, resource, maxfixes=1):
+        self.project = project
+        self.code = code
+        self.resource = resource
+        self.maxfixes = maxfixes
+
+    @utils.saveit
+    def get_pymodule(self):
+        """Get a `PyModule`"""
+        msg = None
+        code = self.code
+        tries = 0
+        while True:
+            try:
+                if tries == 0 and self.resource is not None and \
+                   self.resource.read() == code:
+                    return self.project.get_pymodule(self.resource,
+                                                     force_errors=True)
+                return libutils.get_string_module(
+                    self.project, code, resource=self.resource,
+                    force_errors=True)
+            except exceptions.ModuleSyntaxError as e:
+                if msg is None:
+                    msg = '%s:%s %s' % (e.filename, e.lineno, e.message_)
+                if tries < self.maxfixes:
+                    tries += 1
+                    self.commenter.comment(e.lineno)
+                    code = '\n'.join(self.commenter.lines)
+                else:
+                    raise exceptions.ModuleSyntaxError(
+                        e.filename, e.lineno,
+                        'Failed to fix error: {0}'.format(msg))
+
+    @property
+    @utils.saveit
+    def commenter(self):
+        return _Commenter(self.code)
+
+    def pyname_at(self, offset):
+        pymodule = self.get_pymodule()
+
+        def old_pyname():
+            word_finder = worder.Worder(self.code, True)
+            expression = word_finder.get_primary_at(offset)
+            expression = expression.replace('\\\n', ' ').replace('\n', ' ')
+            lineno = self.code.count('\n', 0, offset)
+            scope = pymodule.get_scope().get_inner_scope_for_line(lineno)
+            return rope.base.evaluate.eval_str(scope, expression)
+        new_code = pymodule.source_code
+
+        def new_pyname():
+            newoffset = self.commenter.transfered_offset(offset)
+            return rope.base.evaluate.eval_location(pymodule, newoffset)
+        if new_code.startswith(self.code[:offset + 1]):
+            return new_pyname()
+        result = old_pyname()
+        if result is None:
+            return new_pyname()
+        return result
+
+
+class _Commenter(object):
+
+    def __init__(self, code):
+        self.code = code
+        self.lines = self.code.split('\n')
+        self.lines.append('\n')
+        self.origs = range(len(self.lines) + 1)
+        self.diffs = [0] * (len(self.lines) + 1)
+
+    def comment(self, lineno):
+        start = _logical_start(self.lines, lineno, check_prev=True) - 1
+        # using self._get_stmt_end() instead of self._get_block_end()
+        # to lower commented lines
+        end = self._get_stmt_end(start)
+        indents = _get_line_indents(self.lines[start])
+        if 0 < start:
+            last_lineno = self._last_non_blank(start - 1)
+            last_line = self.lines[last_lineno]
+            if last_line.rstrip().endswith(':'):
+                indents = _get_line_indents(last_line) + 4
+        self._set(start, ' ' * indents + 'pass')
+        for line in range(start + 1, end + 1):
+            self._set(line, self.lines[start])
+        self._fix_incomplete_try_blocks(lineno, indents)
+
+    def transfered_offset(self, offset):
+        lineno = self.code.count('\n', 0, offset)
+        diff = sum(self.diffs[:lineno])
+        return offset + diff
+
+    def _last_non_blank(self, start):
+        while start > 0 and self.lines[start].strip() == '':
+            start -= 1
+        return start
+
+    def _get_block_end(self, lineno):
+        end_line = lineno
+        base_indents = _get_line_indents(self.lines[lineno])
+        for i in range(lineno + 1, len(self.lines)):
+            if _get_line_indents(self.lines[i]) >= base_indents:
+                end_line = i
+            else:
+                break
+        return end_line
+
+    def _get_stmt_end(self, lineno):
+        base_indents = _get_line_indents(self.lines[lineno])
+        for i in range(lineno + 1, len(self.lines)):
+            if _get_line_indents(self.lines[i]) <= base_indents:
+                return i - 1
+        return lineno
+
+    def _fix_incomplete_try_blocks(self, lineno, indents):
+        block_start = lineno
+        last_indents = indents
+        while block_start > 0:
+            block_start = rope.base.codeanalyze.get_block_start(
+                ArrayLinesAdapter(self.lines), block_start) - 1
+            if self.lines[block_start].strip().startswith('try:'):
+                indents = _get_line_indents(self.lines[block_start])
+                if indents > last_indents:
+                    continue
+                last_indents = indents
+                block_end = self._find_matching_deindent(block_start)
+                line = self.lines[block_end].strip()
+                if not (line.startswith('finally:') or
+                        line.startswith('except ') or
+                        line.startswith('except:')):
+                    self._insert(block_end, ' ' * indents + 'finally:')
+                    self._insert(block_end + 1, ' ' * indents + '    pass')
+
+    def _find_matching_deindent(self, line_number):
+        indents = _get_line_indents(self.lines[line_number])
+        current_line = line_number + 1
+        while current_line < len(self.lines):
+            line = self.lines[current_line]
+            if not line.strip().startswith('#') and not line.strip() == '':
+                # HACK: We should have used logical lines here
+                if _get_line_indents(self.lines[current_line]) <= indents:
+                    return current_line
+            current_line += 1
+        return len(self.lines) - 1
+
+    def _set(self, lineno, line):
+        self.diffs[self.origs[lineno]] += len(line) - len(self.lines[lineno])
+        self.lines[lineno] = line
+
+    def _insert(self, lineno, line):
+        self.diffs[self.origs[lineno]] += len(line) + 1
+        self.origs.insert(lineno, self.origs[lineno])
+        self.lines.insert(lineno, line)
+
+
+def _logical_start(lines, lineno, check_prev=False):
+    logical_finder = LogicalLineFinder(ArrayLinesAdapter(lines))
+    if check_prev:
+        prev = lineno - 1
+        while prev > 0:
+            start, end = logical_finder.logical_line_in(prev)
+            if end is None or start <= lineno < end:
+                return start
+            if start <= prev:
+                break
+            prev -= 1
+    return logical_finder.logical_line_in(lineno)[0]
+
+
+def _get_line_indents(line):
+    return rope.base.codeanalyze.count_line_indents(line)