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use crate::{encode_section, ComponentArg, ComponentSection, ComponentSectionId, Encode};

/// Represents an export for a WebAssembly component.
pub type ComponentExport = ComponentArg;

/// An encoder for the export section of WebAssembly component.
///
/// # Example
///
/// ```rust
/// use wasm_encoder::{Component, ComponentExportSection, ComponentExport};
///
/// // This exports an instance named "foo" that exports a function named "bar".
/// let mut exports = ComponentExportSection::new();
/// exports.export("foo", ComponentExport::Function(0));
///
/// let mut component = Component::new();
/// component.section(&exports);
///
/// let bytes = component.finish();
/// ```
#[derive(Clone, Debug, Default)]
pub struct ComponentExportSection {
    bytes: Vec<u8>,
    num_added: u32,
}

impl ComponentExportSection {
    /// Create a new component export section encoder.
    pub fn new() -> Self {
        Self::default()
    }

    /// The number of exports in the section.
    pub fn len(&self) -> u32 {
        self.num_added
    }

    /// Determines if the section is empty.
    pub fn is_empty(&self) -> bool {
        self.num_added == 0
    }

    /// Define an export in the export section.
    pub fn export(&mut self, name: &str, export: impl Into<ComponentExport>) -> &mut Self {
        name.encode(&mut self.bytes);
        export.into().encode(&mut self.bytes);
        self.num_added += 1;
        self
    }
}

impl Encode for ComponentExportSection {
    fn encode(&self, sink: &mut Vec<u8>) {
        encode_section(
            sink,
            ComponentSectionId::Export,
            self.num_added,
            &self.bytes,
        );
    }
}

impl ComponentSection for ComponentExportSection {}