feat(vscode): completions for bring and hiding more irrelevant comp…

…letions (#4433)

#### Stops completions on the left side of variable declarations
##### Fixes #3991
<img width="331" alt="image" src="https://github.com/winglang/wing/assets/1237390/5c5c7fed-c416-41ec-ba66-b2b3628d5597">

#### Stops completions in the `in` part of `for in` (prevent the common annoying `inflight` completions)
##### Fixes #3997
<img width="377" alt="image" src="https://github.com/winglang/wing/assets/1237390/ab776893-6cea-4aed-a4d5-bcee27025964">


#### Adds completions for `bring` (and prevent irrelevant completions)
##### Fixes #3975
<img width="599" alt="image" src="https://github.com/winglang/wing/assets/1237390/8118cce8-c2f6-49fb-8f72-0564062dfa82">

_Didn't add documentation for them yet, wasn't sure how to go about it without some duplicated hardcoding._

---

Misc:
- `bring` followed by a single character previously caused a panic (e.g. `bring c`). Most people probably didn't notice cause they were typing `bring cloud` so fast
- No completions in comments or strings
- Tried to centralize many of the cases where it's obvious there will be no completions available. `completions.rs` is still begging for a rewrite.

*By submitting this pull request, I confirm that my contribution is made under the terms of the [Wing Cloud Contribution License](https://github.com/winglang/wing/blob/main/CONTRIBUTION_LICENSE.md)*.

examples/tests/invalid/bring.test.w

@@ -4,4 +4,8 @@ bring cloud;
 bring cloud;
 //    ^^^^^ "cloud" is already defined
 bring fs;
-//    ^^^^^ "fs" is not a built-in module
+//    ^^^^^ "fs" is not a built-in module
+bring ;
+//^^^^^ Expected module specification (see https://www.winglang.io/docs/libraries)
+bring c;
+//^^^^^^ "c" is not a built-in module

libs/tree-sitter-wing/grammar.js

@@ -124,7 +124,7 @@ module.exports = grammar({
     import_statement: ($) =>
       seq(
         "bring",
-        field("module_name", choice($.identifier, $.string)),
+        optional(field("module_name", choice($.identifier, $.string))),
         optional(seq("as", field("alias", $.identifier))),
         $._semicolon
       ),

libs/wingc/src/lsp/completions.rs

@@ -20,7 +20,7 @@ use crate::type_check::{
 };
 use crate::visit::{visit_expr, visit_type_annotation, Visit};
 use crate::wasm_util::{ptr_to_string, string_to_combined_ptr, WASM_RETURN_ERROR};
-use crate::{UTIL_CLASS_NAME, WINGSDK_ASSEMBLY_NAME, WINGSDK_STD_MODULE};
+use crate::{UTIL_CLASS_NAME, WINGSDK_ASSEMBLY_NAME, WINGSDK_BRINGABLE_MODULES, WINGSDK_STD_MODULE};
 
 use super::sync::check_utf8;
 
@@ -38,6 +38,72 @@ pub unsafe extern "C" fn wingc_on_completion(ptr: u32, len: u32) -> u64 {
 	}
 }
 
+/// Using tree-sitter data only, check if there should be no valid completions at this position.
+/// This allows for quick short-circuits to avoid visiting the AST for unambiguous cases.
+/// Returns true if there should be no completions, false otherwise
+fn check_ts_to_completions(interesting_node: &Node) -> bool {
+	let interesting_node_kind = interesting_node.kind();
+
+	let mut no_completions = match interesting_node_kind {
+		"comment" => true,
+
+		// Loose backslash? Get outta here
+		"\\" => true,
+
+		// Strings are just strings
+		// TODO Remove this for https://github.com/winglang/wing/issues/4420
+		"string" | "\"" => true,
+
+		// After "for", we are expecting a variable name
+		"for" => true,
+
+		// we are at the end of an import statement and/or expecting an alias
+		"import_statement" | "as" => true,
+
+		// Starting a definition
+		"let" | "reassignable" => true,
+
+		// Following the keyword of a block-style declaration
+		"class" | "struct" | "interface" | "test" => true,
+
+		// Starting an inflight closure
+		"inflight_specifier" => true,
+
+		// No completions are valid immediately following a closing brace
+		")" | "}" | "]" => true,
+
+		// There will always be options following a colon
+		":" => return false,
+
+		_ => false,
+	};
+
+	if no_completions {
+		return no_completions;
+	}
+
+	if let Some(parent) = interesting_node.parent() {
+		let parent_kind = parent.kind();
+
+		no_completions = match parent_kind {
+			"ERROR" => {
+				if let Some(first_child) = parent.child(0) {
+					match first_child.kind() {
+						"for" => matches!(interesting_node_kind, "in" | "identifier"),
+						"let" => !matches!(interesting_node_kind, "="),
+						_ => false,
+					}
+				} else {
+					false
+				}
+			}
+			_ => false,
+		};
+	}
+
+	no_completions
+}
+
 pub fn on_completion(params: lsp_types::CompletionParams) -> CompletionResponse {
 	WING_TYPES.with(|types| {
 		let mut types = types.borrow_mut();
@@ -86,6 +152,30 @@ pub fn on_completion(params: lsp_types::CompletionParams) -> CompletionResponse
 			);
 			let node_to_complete_kind = node_to_complete.kind();
 
+			if check_ts_to_completions(&node_to_complete) {
+				return vec![];
+			}
+
+			if matches!(node_to_complete.parent(), Some(p) if p.kind() == "import_statement")
+				&& matches!(node_to_complete_kind, "identifier" | "bring")
+			{
+				let mut modules = WINGSDK_BRINGABLE_MODULES
+					.map(|module| CompletionItem {
+						label: module.to_string(),
+						kind: Some(CompletionItemKind::MODULE),
+						..Default::default()
+					})
+					.to_vec();
+				modules.push(CompletionItem {
+					label: "\"module\"".to_string(),
+					insert_text: Some("\"$1\" as $2".to_string()),
+					kind: Some(CompletionItemKind::SNIPPET),
+					insert_text_format: Some(InsertTextFormat::SNIPPET),
+					..Default::default()
+				});
+				return modules;
+			}
+
 			let mut scope_visitor = ScopeVisitor::new(
 				node_to_complete.parent().map(|parent| WingSpan {
 					start: parent.start_position().into(),
@@ -395,9 +485,6 @@ fn get_current_scope_completions(
 	let mut in_type = preceding_text.ends_with(':');
 
 	match node_to_complete.kind() {
-		// there are no possible completions that could follow ")"
-		")" => return vec![],
-
 		"set_literal" | "struct_literal" => {
 			in_type = false;
 		}
@@ -439,11 +526,6 @@ fn get_current_scope_completions(
 			});
 		}
 
-		// in block-style statements, there are no possible completions that can follow the keyword
-		"interface" | "struct" | "class" | "test" => {
-			return vec![];
-		}
-
 		_ => {}
 	}
 
@@ -1485,4 +1567,74 @@ let x: Outer = { bThing: {   } }
                          //^
 "#
 	);
+
+	test_completion_list!(
+		bring_suggestions,
+		r#"
+bring 
+    //^
+"#
+	);
+
+	test_completion_list!(
+		bring_suggestions_partial,
+		r#"
+bring c
+     //^
+"#
+	);
+
+	test_completion_list!(
+		bring_alias,
+		r#"
+bring "" as 
+	        //^
+"#,
+		assert!(bring_alias.is_empty())
+	);
+
+	test_completion_list!(
+		definition_identifier_partial,
+		r#"
+let a
+   //^
+"#,
+		assert!(definition_identifier_partial.is_empty())
+	);
+
+	test_completion_list!(
+		definition_identifier,
+		r#"
+let 
+  //^
+"#,
+		assert!(definition_identifier.is_empty())
+	);
+
+	test_completion_list!(
+		string_inner,
+		r#"
+let x = ""
+       //^
+"#,
+		assert!(string_inner.is_empty())
+	);
+
+	test_completion_list!(
+		for_in_inner,
+		r#"
+for x i
+     //^
+"#,
+		assert!(for_in_inner.is_empty())
+	);
+
+	test_completion_list!(
+		comment,
+		r#"
+let x = // hi 
+            //^
+"#,
+		assert!(comment.is_empty())
+	);
 }

libs/wingc/src/lsp/snapshots/completions/bring_alias.snap

@@ -0,0 +1,5 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+[]
+

libs/wingc/src/lsp/snapshots/completions/bring_suggestions.snap

@@ -0,0 +1,30 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+- label: aws
+  kind: 9
+  sortText: kk|aws
+- label: cloud
+  kind: 9
+  sortText: kk|cloud
+- label: ex
+  kind: 9
+  sortText: kk|ex
+- label: http
+  kind: 9
+  sortText: kk|http
+- label: math
+  kind: 9
+  sortText: kk|math
+- label: regex
+  kind: 9
+  sortText: kk|regex
+- label: util
+  kind: 9
+  sortText: kk|util
+- label: "\"module\""
+  kind: 15
+  sortText: "ll|\"module\""
+  insertText: "\"$1\" as $2"
+  insertTextFormat: 2
+

libs/wingc/src/lsp/snapshots/completions/bring_suggestions_partial.snap

@@ -0,0 +1,30 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+- label: aws
+  kind: 9
+  sortText: kk|aws
+- label: cloud
+  kind: 9
+  sortText: kk|cloud
+- label: ex
+  kind: 9
+  sortText: kk|ex
+- label: http
+  kind: 9
+  sortText: kk|http
+- label: math
+  kind: 9
+  sortText: kk|math
+- label: regex
+  kind: 9
+  sortText: kk|regex
+- label: util
+  kind: 9
+  sortText: kk|util
+- label: "\"module\""
+  kind: 15
+  sortText: "ll|\"module\""
+  insertText: "\"$1\" as $2"
+  insertTextFormat: 2
+

libs/wingc/src/lsp/snapshots/completions/comment.snap

@@ -0,0 +1,5 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+[]
+

libs/wingc/src/lsp/snapshots/completions/definition_identifier.snap

@@ -0,0 +1,5 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+[]
+

libs/wingc/src/lsp/snapshots/completions/definition_identifier_partial.snap

@@ -0,0 +1,5 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+[]
+

libs/wingc/src/lsp/snapshots/completions/for_in_inner.snap

@@ -0,0 +1,5 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+[]
+

libs/wingc/src/lsp/snapshots/completions/string_inner.snap

@@ -0,0 +1,5 @@
+---
+source: libs/wingc/src/lsp/completions.rs
+---
+[]
+

libs/wingc/src/parser.rs

@@ -791,15 +791,23 @@ impl<'s> Parser<'s> {
 	}
 
 	fn build_bring_statement(&self, statement_node: &Node) -> DiagnosticResult<StmtKind> {
-		let module_name_node = self.get_child_field(&statement_node, "module_name")?;
+		let Some(module_name_node) = statement_node.child_by_field_name("module_name") else {
+			return self.with_error("Expected module specification (see https://www.winglang.io/docs/libraries)", &statement_node.child(statement_node.child_count() - 1).unwrap_or(*statement_node));
+		};
+
 		let module_name = self.node_symbol(&module_name_node)?;
 		let alias = if let Some(identifier) = statement_node.child_by_field_name("alias") {
 			Some(self.check_reserved_symbol(&identifier)?)
 		} else {
 			None
 		};
 
-		let module_path = Utf8Path::new(&module_name.name[1..module_name.name.len() - 1]);
+		let module_path = if module_name.name.len() > 1 {
+			Utf8Path::new(&module_name.name[1..module_name.name.len() - 1])
+		} else {
+			Utf8Path::new(&module_name.name)
+		};
+
 		if is_absolute_path(&module_path) {
 			return self.with_error(
 				format!("Cannot bring \"{}\" since it is not a relative path", module_path),

tools/hangar/__snapshots__/invalid.ts.snap

@@ -273,7 +273,14 @@ Duration <DURATION>"
 `;
 
 exports[`bring.test.w 1`] = `
-"error: Redundant bring of \\"std\\"
+"error: Expected module specification (see https://www.winglang.io/docs/libraries)
+  --> ../../../examples/tests/invalid/bring.test.w:8:7
+  |
+8 | bring ;
+  |       ^ Expected module specification (see https://www.winglang.io/docs/libraries)
+
+
+error: Redundant bring of \\"std\\"
   --> ../../../examples/tests/invalid/bring.test.w:1:1
   |
 1 | bring std;
@@ -294,6 +301,13 @@ error: \\"fs\\" is not a built-in module
   | ^^^^^^^^^ \\"fs\\" is not a built-in module
 
 
+error: \\"c\\" is not a built-in module
+   --> ../../../examples/tests/invalid/bring.test.w:10:1
+   |
+10 | bring c;
+   | ^^^^^^^^ \\"c\\" is not a built-in module
+
+
  
  
 Tests 1 failed (1)