Reorganize completions structure

crates/completion/src/config.rs

@@ -0,0 +1,35 @@
+//! Settings for tweaking completion.
+//!
+//! The fun thing here is `SnippetCap` -- this type can only be created in this
+//! module, and we use to statically check that we only produce snippet
+//! completions if we are allowed to.
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CompletionConfig {
+    pub enable_postfix_completions: bool,
+    pub add_call_parenthesis: bool,
+    pub add_call_argument_snippets: bool,
+    pub snippet_cap: Option<SnippetCap>,
+}
+
+impl CompletionConfig {
+    pub fn allow_snippets(&mut self, yes: bool) {
+        self.snippet_cap = if yes { Some(SnippetCap { _private: () }) } else { None }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct SnippetCap {
+    _private: (),
+}
+
+impl Default for CompletionConfig {
+    fn default() -> Self {
+        CompletionConfig {
+            enable_postfix_completions: true,
+            add_call_parenthesis: true,
+            add_call_argument_snippets: true,
+            snippet_cap: Some(SnippetCap { _private: () }),
+        }
+    }
+}