formatx 0.2.4

A macro for formatting non literal strings at runtime
Documentation 
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use crate::error::Error;
use crate::format_spec::FormatSpec;

/// Template placeholder specifications.
#[derive(Debug, Clone)]
pub struct Placeholder {
    pub attributes: Option<String>,
    pub format_spec: FormatSpec,
    pub replacer: String,
}

impl Placeholder {
    /// Parse template string and deserialize it to `Self`.
    pub fn new(template: &str, placeholder: &str) -> Result<Option<Self>, Error> {
        if let Some(start) = template.find(&format!("{{{}", placeholder)) {
            let matched = &template[(start + 1)..(start + template[start..].find('}').unwrap())];

            let attributes = if matched.rfind(':').is_some() {
                let mut attributes = matched.split(':').collect::<Vec<&str>>();
                let _ = attributes.pop();
                attributes
                    .join(":")
                    .trim_start_matches(placeholder)
                    .trim()
                    .to_owned()
            } else {
                matched.trim_start_matches(placeholder).trim().to_owned()
            };

            let attributes = if attributes.is_empty() {
                None
            } else {
                Some(attributes)
            };

            return Ok(Some(Self {
                attributes,
                format_spec: FormatSpec::new(matched)?,
                replacer: format!("{{{}}}", matched),
            }));
        }

        Ok(None)
    }

    /// Get attribute value if present else returns `None`.
    ///
    /// Attributes can be defined for as:
    ///
    /// ```text
    /// 1. name=emily -> Some("emily")
    /// 2. name="emily cooper" -> Some("emily cooper")
    /// 3. name='emily clarke' -> Some("emily clarke")
    /// ```
    pub fn attr(&self, attribute: &str) -> Option<String> {
        if let Some(attributes) = &self.attributes {
            let attribute_identifier = format!("{}=", attribute);

            if let Some(attribute_index) = attributes.find(&attribute_identifier) {
                let value = attributes[attribute_index..].trim_start_matches(&attribute_identifier);

                if let Some(stripped) = value.strip_prefix('\"') {
                    return Some(value[1..(stripped.find('\"')? + 1)].to_owned());
                } else if let Some(stripped) = value.strip_prefix('\'') {
                    return Some(value[1..(stripped.find('\'')? + 1)].to_owned());
                } else {
                    return value.split(' ').next().map(|x| x.to_owned());
                }
            }
        }

        None
    }
}