Change/bert encoder public (#2658)

* change: BertEncoder struct to public

* change: make certain fields in Config struct public

* change: all fields in bert config struct to be public

* change: add clone to bert encoder and others

* Clippy fix.

---------

Co-authored-by: Laurent <laurent.mazare@gmail.com>

candle-transformers/src/models/bert.rs

@@ -22,6 +22,7 @@ pub enum HiddenAct {
     Relu,
 }
 
+#[derive(Clone)]
 struct HiddenActLayer {
     act: HiddenAct,
     span: tracing::Span,
@@ -46,7 +47,7 @@ impl HiddenActLayer {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, Default)]
 #[serde(rename_all = "lowercase")]
-enum PositionEmbeddingType {
+pub enum PositionEmbeddingType {
     #[default]
     Absolute,
 }
@@ -54,24 +55,24 @@ enum PositionEmbeddingType {
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/configuration_bert.py#L1
 #[derive(Debug, Clone, PartialEq, Deserialize)]
 pub struct Config {
-    vocab_size: usize,
-    hidden_size: usize,
-    num_hidden_layers: usize,
-    num_attention_heads: usize,
-    intermediate_size: usize,
+    pub vocab_size: usize,
+    pub hidden_size: usize,
+    pub num_hidden_layers: usize,
+    pub num_attention_heads: usize,
+    pub intermediate_size: usize,
     pub hidden_act: HiddenAct,
-    hidden_dropout_prob: f64,
-    max_position_embeddings: usize,
-    type_vocab_size: usize,
-    initializer_range: f64,
-    layer_norm_eps: f64,
-    pad_token_id: usize,
+    pub hidden_dropout_prob: f64,
+    pub max_position_embeddings: usize,
+    pub type_vocab_size: usize,
+    pub initializer_range: f64,
+    pub layer_norm_eps: f64,
+    pub pad_token_id: usize,
     #[serde(default)]
-    position_embedding_type: PositionEmbeddingType,
+    pub position_embedding_type: PositionEmbeddingType,
     #[serde(default)]
-    use_cache: bool,
-    classifier_dropout: Option<f64>,
-    model_type: Option<String>,
+    pub use_cache: bool,
+    pub classifier_dropout: Option<f64>,
+    pub model_type: Option<String>,
 }
 
 impl Default for Config {
@@ -121,6 +122,7 @@ impl Config {
     }
 }
 
+#[derive(Clone)]
 struct Dropout {
     #[allow(dead_code)]
     pr: f64,
@@ -199,6 +201,7 @@ impl BertEmbeddings {
     }
 }
 
+#[derive(Clone)]
 struct BertSelfAttention {
     query: Linear,
     key: Linear,
@@ -266,6 +269,7 @@ impl BertSelfAttention {
     }
 }
 
+#[derive(Clone)]
 struct BertSelfOutput {
     dense: Linear,
     layer_norm: LayerNorm,
@@ -299,6 +303,7 @@ impl BertSelfOutput {
 }
 
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/modeling_bert.py#L392
+#[derive(Clone)]
 struct BertAttention {
     self_attention: BertSelfAttention,
     self_output: BertSelfOutput,
@@ -325,6 +330,7 @@ impl BertAttention {
 }
 
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/modeling_bert.py#L441
+#[derive(Clone)]
 struct BertIntermediate {
     dense: Linear,
     intermediate_act: HiddenActLayer,
@@ -352,6 +358,7 @@ impl Module for BertIntermediate {
 }
 
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/modeling_bert.py#L456
+#[derive(Clone)]
 struct BertOutput {
     dense: Linear,
     layer_norm: LayerNorm,
@@ -385,7 +392,8 @@ impl BertOutput {
 }
 
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/modeling_bert.py#L470
-struct BertLayer {
+#[derive(Clone)]
+pub struct BertLayer {
     attention: BertAttention,
     intermediate: BertIntermediate,
     output: BertOutput,
@@ -420,13 +428,14 @@ impl BertLayer {
 }
 
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/modeling_bert.py#L556
-struct BertEncoder {
-    layers: Vec<BertLayer>,
+#[derive(Clone)]
+pub struct BertEncoder {
+    pub layers: Vec<BertLayer>,
     span: tracing::Span,
 }
 
 impl BertEncoder {
-    fn load(vb: VarBuilder, config: &Config) -> Result<Self> {
+    pub fn load(vb: VarBuilder, config: &Config) -> Result<Self> {
         let layers = (0..config.num_hidden_layers)
             .map(|index| BertLayer::load(vb.pp(format!("layer.{index}")), config))
             .collect::<Result<Vec<_>>>()?;
@@ -434,7 +443,7 @@ impl BertEncoder {
         Ok(BertEncoder { layers, span })
     }
 
-    fn forward(&self, hidden_states: &Tensor, attention_mask: &Tensor) -> Result<Tensor> {
+    pub fn forward(&self, hidden_states: &Tensor, attention_mask: &Tensor) -> Result<Tensor> {
         let _enter = self.span.enter();
         let mut hidden_states = hidden_states.clone();
         // Use a loop rather than a fold as it's easier to modify when adding debug/...