completion context getting ahead

Author: juleswritescode

crates/pg_completions/src/context.rs

@@ -1,9 +1,48 @@
+use pg_schema_cache::SchemaCache;
+
 use crate::CompletionParams;
 
-pub struct CompletionContext {}
+pub struct CompletionContext<'a> {
+    pub ts_node: Option<tree_sitter::Node<'a>>,
+    pub tree: Option<&'a tree_sitter::Tree>,
+    pub text: &'a str,
+    pub schema_cache: &'a SchemaCache,
+    pub original_token: Option<char>,
+}
 
-impl CompletionContext {
-    pub fn new(params: &CompletionParams) -> Self {
-        todo!()
+impl<'a> CompletionContext<'a> {
+    pub fn new(params: &'a CompletionParams) -> Self {
+        Self {
+            ts_node: find_ts_node(params),
+            tree: params.tree,
+            text: params.text,
+            schema_cache: params.schema,
+            original_token: find_original_token(params),
+        }
     }
 }
+
+fn find_original_token<'a>(params: &'a CompletionParams) -> Option<char> {
+    let idx = usize::from(params.position);
+    params.text.chars().nth(idx)
+}
+
+fn find_ts_node<'a>(params: &'a CompletionParams) -> Option<tree_sitter::Node<'a>> {
+    let tree = params.tree?;
+
+    let mut node = tree.root_node().named_descendant_for_byte_range(
+        usize::from(params.position),
+        usize::from(params.position),
+    )?;
+
+    let node_range = node.range();
+    while let Some(parent) = node.parent() {
+        if parent.range() != node_range {
+            break;
+        }
+
+        node = parent;
+    }
+
+    Some(node)
+}