Teach the server about Semantic Tokens proposed LSP

crates/rust-analyzer/src/semantic_tokens.rs

@@ -0,0 +1,86 @@
+use lsp_types::{Range, SemanticToken, SemanticTokenModifier, SemanticTokenType};
+
+const SUPPORTED_TYPES: &[SemanticTokenType] = &[
+    SemanticTokenType::COMMENT,
+    SemanticTokenType::KEYWORD,
+    SemanticTokenType::STRING,
+    SemanticTokenType::NUMBER,
+    SemanticTokenType::REGEXP,
+    SemanticTokenType::OPERATOR,
+    SemanticTokenType::NAMESPACE,
+    SemanticTokenType::TYPE,
+    SemanticTokenType::STRUCT,
+    SemanticTokenType::CLASS,
+    SemanticTokenType::INTERFACE,
+    SemanticTokenType::ENUM,
+    SemanticTokenType::TYPE_PARAMETER,
+    SemanticTokenType::FUNCTION,
+    SemanticTokenType::MEMBER,
+    SemanticTokenType::PROPERTY,
+    SemanticTokenType::MACRO,
+    SemanticTokenType::VARIABLE,
+    SemanticTokenType::PARAMETER,
+    SemanticTokenType::LABEL,
+];
+
+const SUPPORTED_MODIFIERS: &[SemanticTokenModifier] = &[
+    SemanticTokenModifier::DOCUMENTATION,
+    SemanticTokenModifier::DECLARATION,
+    SemanticTokenModifier::DEFINITION,
+    SemanticTokenModifier::REFERENCE,
+    SemanticTokenModifier::STATIC,
+    SemanticTokenModifier::ABSTRACT,
+    SemanticTokenModifier::DEPRECATED,
+    SemanticTokenModifier::ASYNC,
+    SemanticTokenModifier::VOLATILE,
+    SemanticTokenModifier::READONLY,
+];
+
+pub(crate) fn supported_token_types() -> &'static [SemanticTokenType] {
+    SUPPORTED_TYPES
+}
+
+pub(crate) fn supported_token_modifiers() -> &'static [SemanticTokenModifier] {
+    SUPPORTED_MODIFIERS
+}
+
+#[derive(Default)]
+pub(crate) struct SemanticTokensBuilder {
+    prev_line: u32,
+    prev_char: u32,
+    data: Vec<SemanticToken>,
+}
+
+impl SemanticTokensBuilder {
+    pub fn push(&mut self, range: Range, token_index: u32, modifier_bitset: u32) {
+        let mut push_line = range.start.line as u32;
+        let mut push_char = range.start.character as u32;
+
+        if !self.data.is_empty() {
+            push_line -= self.prev_line;
+            if push_line == 0 {
+                push_char -= self.prev_char;
+            }
+        }
+
+        // A token cannot be multiline
+        let token_len = range.end.character - range.start.character;
+
+        let token = SemanticToken {
+            delta_line: push_line,
+            delta_start: push_char,
+            length: token_len as u32,
+            token_type: token_index,
+            token_modifiers_bitset: modifier_bitset,
+        };
+
+        self.data.push(token);
+
+        self.prev_line = range.start.line as u32;
+        self.prev_char = range.start.character as u32;
+    }
+
+    pub fn build(self) -> Vec<SemanticToken> {
+        self.data
+    }
+}