# Copyright 2023 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Helpers to parse content of xml files."""
import html
from xml.dom import minidom
from typing import Iterator
_ELEMENT_NODE = minidom.Node.ELEMENT_NODE
def GetTagSubTree(tree: minidom.Element, tag: str,
depth: int) -> minidom.Element:
"""Returns sub tree with tag element as a root.
When no element with tag name is found or there are many of them
original tree is returned.
Args:
tree: XML dom tree.
tag: Element's tag name.
depth: Defines how deep in the tree function should search for a match.
Returns:
xml.dom.minidom.Node: Sub tree (matching criteria) or original one.
"""
entries = list(IterElementsWithTag(tree, tag, depth))
if len(entries) == 1:
tree = entries[0]
return tree
def NormalizeString(text: str) -> str:
r"""Replaces all white space sequences with a single space.
Also, unescapes any HTML escaped characters, e.g. " or >.
Args:
text: The string to normalize, '\n\n a \n b>c '.
Returns:
The normalized string 'a b>c'.
"""
line = ' '.join(text.split())
# Unescape using default ASCII encoding. Unescapes any HTML escaped character
# like " etc.
return html.unescape(line)
def NormalizeAllAttributeValues(node: minidom.Element) -> minidom.Element:
"""Recursively normalizes all tag attribute values in the given tree.
Args:
node: The minidom node to be normalized.
Returns:
The normalized minidom node.
"""
if node.nodeType == _ELEMENT_NODE:
for a in node.attributes.keys():
node.attributes[a].value = NormalizeString(node.attributes[a].value)
for c in node.childNodes:
NormalizeAllAttributeValues(c)
return node
def GetTextFromChildNodes(node: minidom.Element) -> str:
"""Returns a string concatenation of the text of the given node's children.
Comments are ignored, consecutive lines of text are joined with a single
space, and paragraphs are maintained so that long text is more readable on
dashboards.
Args:
node: The DOM Element whose children's text is to be extracted, processed,
and returned.
Returns:
A string concatenation of the text of the given node's children.
"""
paragraph_break = '\n\n'
text_parts = []
for child in node.childNodes:
if child.nodeType != minidom.Node.COMMENT_NODE:
child_text = child.toxml()
if not child_text:
continue
# If the given node has the below XML representation, then the text
# added to the list is 'Some words.\n\nWords.'
# <tag>
# Some
# words.
#
# <!--Child comment node.-->
#
# Words.
# </tag>
# In the case of the first child text node, raw_paragraphs would store
# ['\n Some\n words.', ' '], and in the case of the second,
# raw_paragraphs would store ['', ' Words.\n'].
raw_paragraphs = child_text.split(paragraph_break)
# In the case of the first child text node, processed_paragraphs would
# store ['Some words.', ''], and in the case of the second,
# processed_paragraphs would store ['Words.'].
processed_paragraphs = [
NormalizeString(text) for text in raw_paragraphs if text
]
text_parts.append(paragraph_break.join(processed_paragraphs))
return ''.join(text_parts).strip()
def IterElementsWithTag(root: minidom.Element,
tag: str,
depth: int = -1) -> Iterator[minidom.Element]:
"""Iterates over DOM tree and yields elements matching tag name.
It's meant to be replacement for `getElementsByTagName`,
(which does recursive search) but without recursive search
(nested tags are not supported in histograms files).
Note: This generator stops going deeper in the tree when it detects
that there are elements with given tag.
Args:
root: XML dom tree.
tag: Element's tag name.
depth: Defines how deep in the tree function should search for a match.
Yields:
xml.dom.minidom.Node: Element matching criteria.
"""
if depth == 0 and root.nodeType == _ELEMENT_NODE and root.tagName == tag:
yield root
return
had_tag = False
skipped = 0
for child in root.childNodes:
if child.nodeType == _ELEMENT_NODE and child.tagName == tag:
had_tag = True
yield child
else:
skipped += 1
depth -= 1
if not had_tag and depth != 0:
for child in root.childNodes:
for match in IterElementsWithTag(child, tag, depth):
yield match
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