Method compute_auto_pause

src/tts.rs:589–628

Compute the length of the pause to use. The computation is based on the length of the speech strings (after removing tagging). There is a bias towards pausing more _after_ longer strings.

(&self, prefs: &PreferenceManager, before: &str, after: &str)

    /// The computation is based on the length of the speech strings (after removing tagging).
    /// There is a bias towards pausing more _after_ longer strings.
    pub fn compute_auto_pause(&self, prefs: &PreferenceManager, before: &str, after: &str) -> String {
        lazy_static! {
            static ref REMOVE_XML: Regex = Regex::new(r"<.+?>").unwrap();    // punctuation ending with a '.'
        }
        let before_len;
        let after_len;
        match self {
            TTS::SSML | TTS::SAPI5 => {
                before_len = REMOVE_XML.replace_all(before, "").len();
                after_len = REMOVE_XML.replace_all(after, "").len();
            },
            _ => {
                before_len = before.len();
                after_len = after.len();
            },
        }

        // pause values are not cut in stone
        // the calculation bias to 'previous' is based on MathPlayer which used '30 * #-of-descendants-on-left
        // I think I did this as a sort of "take a breath" after saying something long although one might want to do that
        //   before speaking something long.
        if after_len < 3 {
            // hack to prevent pausing before "of" in exprs like "the fourth power of secant, of x"
            // if it should pause anywhere, it should be after the "of"
            return "".to_string(); 
        }
        let pause = std::cmp::min(3000, ((2 * before_len + after_len)/48) * 128);
        // create a TTSCommandRule so we reuse code
        let command = TTSCommandRule::new(
            TTSCommand::Pause,
            TTSCommandValue::Number(pause as f64),
            ReplacementArray::build_empty(),
        );
        return match self {
            TTS::None  => self.get_string_none(&command, prefs, true),
            TTS::SSML  => self.get_string_ssml(&command, prefs, true),
            TTS::SAPI5 => self.get_string_sapi5(&command, prefs, true),
        };

    }

    /// Take the longest of the pauses
    ///