Expose pooling type

Author: LucGeven

llama-cpp-2/src/context/params.rs

@@ -41,6 +41,49 @@ impl From<RopeScalingType> for i32 {
     }
 }
 
+/// A rusty wrapper around `LLAMA_POOLING_TYPE`.
+#[repr(i8)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum LlamaPoolingType {
+    /// The pooling type is unspecified
+    Unspecified = -1,
+    /// No pooling    
+    None = 0,
+    /// Mean pooling
+    Mean = 1,
+    /// CLS pooling
+    Cls = 2,
+    /// Last pooling
+    Last = 3,
+}
+
+/// Create a `LlamaPoolingType` from a `c_int` - returns `LlamaPoolingType::Unspecified` if
+/// the value is not recognized.
+impl From<i32> for LlamaPoolingType {
+    fn from(value: i32) -> Self {
+        match value {
+            0 => Self::None,
+            1 => Self::Mean,
+            2 => Self::Cls,
+            3 => Self::Last,
+            _ => Self::Unspecified,
+        }
+    }
+}
+
+/// Create a `c_int` from a `LlamaPoolingType`.
+impl From<LlamaPoolingType> for i32 {
+    fn from(value: LlamaPoolingType) -> Self {
+        match value {
+            LlamaPoolingType::None => 0,
+            LlamaPoolingType::Mean => 1,
+            LlamaPoolingType::Cls => 2,
+            LlamaPoolingType::Last => 3,
+            LlamaPoolingType::Unspecified => -1,
+        }
+    }
+}
+
 /// A safe wrapper around `llama_context_params`.
 ///
 /// Generally this should be created with [`Default::default()`] and then modified with `with_*` methods.
@@ -471,6 +514,35 @@ impl LlamaContextParams {
         self.context_params.cb_eval_user_data = cb_eval_user_data;
         self
     }
+
+    /// Set the type of pooling.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use llama_cpp_2::context::params::{LlamaContextParams, LlamaPoolingType};
+    /// let params = LlamaContextParams::default()
+    ///     .with_pooling_type(LlamaPoolingType::Last);
+    /// assert_eq!(params.pooling_type(), LlamaPoolingType::Last);
+    /// ```
+    #[must_use]
+    pub fn with_pooling_type(mut self, pooling_type: LlamaPoolingType) -> Self {
+        self.context_params.pooling_type = i32::from(pooling_type);
+        self
+    }
+
+    /// Get the type of pooling.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// let params = llama_cpp_2::context::params::LlamaContextParams::default();
+    /// assert_eq!(params.pooling_type(), llama_cpp_2::context::params::LlamaPoolingType::Unspecified);
+    /// ```
+    #[must_use]
+    pub fn pooling_type(&self) -> LlamaPoolingType {
+        LlamaPoolingType::from(self.context_params.pooling_type)
+    }
 }
 
 /// Default parameters for `LlamaContext`. (as defined in llama.cpp by `llama_context_default_params`)