zrx-id 0.0.15

Identifier abstractions and utilities
Documentation
// Copyright (c) 2025-2026 Zensical and contributors

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// ----------------------------------------------------------------------------

//! Iterator over terms.

use slab::Iter;

use crate::id::expression::Term;

use super::condition::Condition;
use super::Filter;

// ----------------------------------------------------------------------------
// Structs
// ----------------------------------------------------------------------------

/// Iterator over terms.
pub struct Terms<'a> {
    /// Condition set, built from expressions.
    conditions: Iter<'a, Condition>,
    /// Current set of extracted terms.
    inner: &'a [Term],
}

// ----------------------------------------------------------------------------
// Implementations
// ----------------------------------------------------------------------------

impl Filter {
    /// Creates an iterator over the terms.
    ///
    /// # Examples
    ///
    /// ```
    /// # use std::error::Error;
    /// # fn main() -> Result<(), Box<dyn Error>> {
    /// use zrx_id::{selector, Expression, Filter};
    ///
    /// // Create filter builder and insert expression
    /// let mut builder = Filter::builder();
    /// builder.insert(Expression::any(|expr| {
    ///     expr.with(selector!(location = "**/*.jpg")?)?
    ///         .with(selector!(location = "**/*.png")?)
    /// })?);
    ///
    /// // Create filter from builder
    /// let filter = builder.build()?;
    ///
    /// // Create iterator over terms
    /// for term in filter.terms() {
    ///     println!("{term:?}");
    /// }
    /// # Ok(())
    /// # }
    /// ```
    #[inline]
    #[must_use]
    pub fn terms(&self) -> Terms<'_> {
        Terms {
            conditions: self.conditions.iter(),
            inner: &[],
        }
    }
}

// ----------------------------------------------------------------------------
// Trait implementations
// ----------------------------------------------------------------------------

impl<'a> Iterator for Terms<'a> {
    type Item = &'a Term;

    /// Returns the next term.
    fn next(&mut self) -> Option<Self::Item> {
        loop {
            // Check if we have terms left in the current condition
            if let Some(term) = self.inner.first() {
                self.inner = &self.inner[1..];
                return Some(term);
            }

            // Fetch next condition and extract its terms
            let (_, condition) = self.conditions.next()?;
            self.inner = condition.terms();
        }
    }
}