Optimize TruncateCharsHTMLParser.process() to avoid redundant sum() calculation

[Tarek Nakkouch]

The TruncateCharsHTMLParser.process() method in django/utils/text.py recalculates sum(len(p) for p in self.output) every time it processes a text chunk. For HTML with multiple text nodes, this repeatedly iterates over the growing output list unnecessarily.

def process(self, data):
    self.processed_chars += len(data)
    if (self.processed_chars == self.length) and (
        sum(len(p) for p in self.output) + len(data) == len(self.rawdata)
    ):
        self.output.append(data)
        raise self.TruncationCompleted
    output = escape("".join(data[: self.remaining]))
    return data, output

Suggested optimization

Cache the output length as self.output_len and increment it when appending to self.output:

• Initialize self.output_len = 0 in TruncateHTMLParser.__init__()
• Increment in handle_starttag(), handle_endtag(), handle_data(), feed(), and process()
• Replace sum(len(p) for p in self.output) with self.output_len

This eliminates redundant iteration over already-processed output.