feat(compiler): addition and subtraction assignment operators impleme…

…ntation (#4018)

Fixes #4005

Implemented a `+=` and `-=` operators, as a new type of `StmtKind::Assignment`.
- [Type Check](https://github.com/winglang/wing/compare/main...wzslr321:feature/compiler/add-and-sub-assignment-ops?expand=1#diff-fe246e49d57ca72d41851e8dacc3d2ccee194881769083dd8ca508058cff13b4R1829) allows only for numbers to be used on both sides of the operator.



## Checklist

- [x] Title matches [Winglang's style guide](https://www.winglang.io/contributing/start-here/pull_requests#how-are-pull-request-titles-formatted)
- [x] Description explains motivation and solution
- [x] Tests added (always)
- [x] Docs updated (only required for features)
- [ ] Added `pr/e2e-full` label if this feature requires end-to-end testing

*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)*.

docs/docs/03-language-reference.md

@@ -657,6 +657,14 @@ for item in [1,2,3] {
 }
 ```
 
+To modify a numeric value, it is also possible to use `+=` and `-=` operators.
+```TS
+// wing
+let var x = 0;
+x += 5; // x == 5
+x -= 10; // x == -5
+```
+
 Re-assignment to class fields is allowed if field is marked with `var`.
 Examples in the class section below.
 

examples/tests/valid/expressions_binary_operators.w

@@ -15,4 +15,5 @@ assert(xyznf == -5);
 let xyznfj = 501.9 \ (-99.1 - 0.91);
 assert(xyznfj == -5);
 let xynfj = -501.9 \ (-99.1 - 0.91);
-assert(xynfj == 5);
+assert(xynfj == 5);
+

examples/tests/valid/reassignment.w

@@ -4,6 +4,13 @@ assert(x == 5);
 x = x + 1;
 assert(x == 6);
 
+let var z = 1;
+z += 2;
+assert(z == 3);
+
+z -= 1;
+assert(z == 2);
+
 class R {
   var f: num;
   f1: num;

libs/tree-sitter-wing/grammar.js

@@ -152,14 +152,17 @@ module.exports = grammar({
     throw_statement: ($) =>
       seq("throw", optional(field("expression", $.expression)), $._semicolon),
 
+    assignment_operator: ($) => choice("=", "+=", "-="),
+
     variable_assignment_statement: ($) =>
       seq(
         field("name", alias($.reference, $.lvalue)),
-        "=",
+        field("operator", $.assignment_operator),
         field("value", $.expression),
         $._semicolon
       ),
 
+
     expression_statement: ($) => seq($.expression, $._semicolon),
 
     reassignable: ($) => "var",

libs/tree-sitter-wing/test/corpus/statements/statements.txt

@@ -72,6 +72,10 @@ Variable assignment
 let x: num = 1;
 x = 2;
 
+let var z = 1;
+z += 2;
+z -= 1;
+
 let var y = "hello";
 
 --------------------------------------------------------------------------------
@@ -84,6 +88,21 @@ let var y = "hello";
   (variable_assignment_statement
     name: (lvalue
       (reference_identifier))
+    operator: (assignment_operator)
+    value: (number))
+  (variable_definition_statement
+    reassignable: (reassignable)
+    name: (identifier)
+    value: (number))
+  (variable_assignment_statement
+    name: (lvalue
+      (reference_identifier))
+    operator: (assignment_operator)
+    value: (number))
+  (variable_assignment_statement
+    name: (lvalue
+      (reference_identifier))
+    operator: (assignment_operator)
     value: (number))
   (variable_definition_statement
     reassignable: (reassignable)

libs/wingc/src/ast.rs

@@ -425,6 +425,13 @@ pub enum BringSource {
 	WingFile(Symbol),
 }
 
+#[derive(Debug)]
+pub enum AssignmentKind {
+	Assign,
+	AssignIncr,
+	AssignDecr,
+}
+
 #[derive(Debug)]
 pub enum StmtKind {
 	Bring {
@@ -469,6 +476,7 @@ pub enum StmtKind {
 	Throw(Expr),
 	Expression(Expr),
 	Assignment {
+		kind: AssignmentKind,
 		variable: Reference,
 		value: Expr,
 	},

libs/wingc/src/closure_transform.rs

@@ -2,9 +2,9 @@ use indexmap::IndexMap;
 
 use crate::{
 	ast::{
-		ArgList, CalleeKind, Class, ClassField, Expr, ExprKind, FunctionBody, FunctionDefinition, FunctionParameter,
-		FunctionSignature, Literal, NewExpr, Phase, Reference, Scope, Stmt, StmtKind, Symbol, TypeAnnotation,
-		TypeAnnotationKind, UserDefinedType,
+		ArgList, AssignmentKind, CalleeKind, Class, ClassField, Expr, ExprKind, FunctionBody, FunctionDefinition,
+		FunctionParameter, FunctionSignature, Literal, NewExpr, Phase, Reference, Scope, Stmt, StmtKind, Symbol,
+		TypeAnnotation, TypeAnnotationKind, UserDefinedType,
 	},
 	diagnostic::WingSpan,
 	fold::{self, Fold},
@@ -213,6 +213,7 @@ impl Fold for ClosureTransformer {
 				let class_init_body = vec![Stmt {
 					idx: 0,
 					kind: StmtKind::Assignment {
+						kind: AssignmentKind::Assign,
 						variable: Reference::InstanceMember {
 							object: Box::new(std_display_of_this),
 							property: Symbol::new("hidden", WingSpan::for_file(file_id)),

libs/wingc/src/fold.rs

@@ -158,7 +158,8 @@ where
 		StmtKind::Return(value) => StmtKind::Return(value.map(|value| f.fold_expr(value))),
 		StmtKind::Throw(value) => StmtKind::Throw(f.fold_expr(value)),
 		StmtKind::Expression(expr) => StmtKind::Expression(f.fold_expr(expr)),
-		StmtKind::Assignment { variable, value } => StmtKind::Assignment {
+		StmtKind::Assignment { kind, variable, value } => StmtKind::Assignment {
+			kind,
 			variable: f.fold_reference(variable),
 			value: f.fold_expr(value),
 		},

libs/wingc/src/jsify.rs

@@ -10,9 +10,9 @@ use std::{borrow::Borrow, cell::RefCell, cmp::Ordering, vec};
 
 use crate::{
 	ast::{
-		ArgList, BinaryOperator, BringSource, CalleeKind, Class as AstClass, ElifLetBlock, Expr, ExprKind, FunctionBody,
-		FunctionDefinition, InterpolatedStringPart, Literal, NewExpr, Phase, Reference, Scope, Stmt, StmtKind, StructField,
-		Symbol, TypeAnnotationKind, UnaryOperator, UserDefinedType,
+		ArgList, AssignmentKind, BinaryOperator, BringSource, CalleeKind, Class as AstClass, ElifLetBlock, Expr, ExprKind,
+		FunctionBody, FunctionDefinition, InterpolatedStringPart, Literal, NewExpr, Phase, Reference, Scope, Stmt,
+		StmtKind, StructField, Symbol, TypeAnnotationKind, UnaryOperator, UserDefinedType,
 	},
 	comp_ctx::{CompilationContext, CompilationPhase},
 	dbg_panic, debug,
@@ -1012,11 +1012,21 @@ impl<'a> JSifier<'a> {
 				code
 			}
 			StmtKind::Expression(e) => CodeMaker::one_line(format!("{};", self.jsify_expression(e, ctx))),
-			StmtKind::Assignment { variable, value } => CodeMaker::one_line(format!(
-				"{} = {};",
-				self.jsify_reference(variable, ctx),
-				self.jsify_expression(value, ctx)
-			)),
+
+			StmtKind::Assignment { kind, variable, value } => {
+				let operator = match kind {
+					AssignmentKind::Assign => "=",
+					AssignmentKind::AssignIncr => "+=",
+					AssignmentKind::AssignDecr => "-=",
+				};
+
+				CodeMaker::one_line(format!(
+					"{} {} {};",
+					self.jsify_reference(variable, ctx),
+					operator,
+					self.jsify_expression(value, ctx)
+				))
+			}
 			StmtKind::Scope(scope) => {
 				let mut code = CodeMaker::default();
 				if !scope.statements.is_empty() {

libs/wingc/src/parser.rs

@@ -8,10 +8,10 @@ use tree_sitter::Node;
 use tree_sitter_traversal::{traverse, Order};
 
 use crate::ast::{
-	ArgList, BinaryOperator, BringSource, CalleeKind, CatchBlock, Class, ClassField, ElifBlock, ElifLetBlock, Expr,
-	ExprKind, FunctionBody, FunctionDefinition, FunctionParameter, FunctionSignature, Interface, InterpolatedString,
-	InterpolatedStringPart, Literal, NewExpr, Phase, Reference, Scope, Stmt, StmtKind, StructField, Symbol,
-	TypeAnnotation, TypeAnnotationKind, UnaryOperator, UserDefinedType,
+	ArgList, AssignmentKind, BinaryOperator, BringSource, CalleeKind, CatchBlock, Class, ClassField, ElifBlock,
+	ElifLetBlock, Expr, ExprKind, FunctionBody, FunctionDefinition, FunctionParameter, FunctionSignature, Interface,
+	InterpolatedString, InterpolatedStringPart, Literal, NewExpr, Phase, Reference, Scope, Stmt, StmtKind, StructField,
+	Symbol, TypeAnnotation, TypeAnnotationKind, UnaryOperator, UserDefinedType,
 };
 use crate::comp_ctx::{CompilationContext, CompilationPhase};
 use crate::diagnostic::{report_diagnostic, Diagnostic, DiagnosticResult, WingSpan};
@@ -438,8 +438,16 @@ impl<'s> Parser<'s> {
 			"import_statement" => self.build_bring_statement(statement_node)?,
 
 			"variable_definition_statement" => self.build_variable_def_statement(statement_node, phase)?,
-			"variable_assignment_statement" => self.build_assignment_statement(statement_node, phase)?,
+			"variable_assignment_statement" => {
+				let kind = match self.node_text(&statement_node.child_by_field_name("operator").unwrap()) {
+					"=" => AssignmentKind::Assign,
+					"+=" => AssignmentKind::AssignIncr,
+					"-=" => AssignmentKind::AssignDecr,
+					other => return self.report_unimplemented_grammar(other, "assignment operator", statement_node),
+				};
 
+				self.build_assignment_statement(statement_node, phase, kind)?
+			}
 			"expression_statement" => {
 				StmtKind::Expression(self.build_expression(&statement_node.named_child(0).unwrap(), phase)?)
 			}
@@ -631,10 +639,17 @@ impl<'s> Parser<'s> {
 		})
 	}
 
-	fn build_assignment_statement(&self, statement_node: &Node, phase: Phase) -> DiagnosticResult<StmtKind> {
+	fn build_assignment_statement(
+		&self,
+		statement_node: &Node,
+		phase: Phase,
+		kind: AssignmentKind,
+	) -> DiagnosticResult<StmtKind> {
 		let reference = self.build_reference(&statement_node.child_by_field_name("name").unwrap(), phase)?;
+
 		if let ExprKind::Reference(r) = reference.kind {
 			Ok(StmtKind::Assignment {
+				kind: kind,
 				variable: r,
 				value: self.build_expression(&statement_node.child_by_field_name("value").unwrap(), phase)?,
 			})

libs/wingc/src/type_check.rs

@@ -4,7 +4,9 @@ pub(crate) mod jsii_importer;
 pub mod lifts;
 pub mod symbol_env;
 
-use crate::ast::{self, BringSource, CalleeKind, ClassField, ExprId, FunctionDefinition, NewExpr, TypeAnnotationKind};
+use crate::ast::{
+	self, AssignmentKind, BringSource, CalleeKind, ClassField, ExprId, FunctionDefinition, NewExpr, TypeAnnotationKind,
+};
 use crate::ast::{
 	ArgList, BinaryOperator, Class as AstClass, Expr, ExprKind, FunctionBody, FunctionParameter as AstFunctionParameter,
 	Interface as AstInterface, InterpolatedStringPart, Literal, Phase, Reference, Scope, Spanned, Stmt, StmtKind, Symbol,
@@ -3131,7 +3133,7 @@ impl<'a> TypeChecker<'a> {
 			StmtKind::Expression(e) => {
 				self.type_check_exp(e, env);
 			}
-			StmtKind::Assignment { variable, value } => {
+			StmtKind::Assignment { kind, variable, value } => {
 				let (exp_type, _) = self.type_check_exp(value, env);
 
 				// TODO: we need to verify that if this variable is defined in a parent environment (i.e.
@@ -3145,6 +3147,11 @@ impl<'a> TypeChecker<'a> {
 					self.spanned_error(stmt, "Variable cannot be reassigned from inflight".to_string());
 				}
 
+				if matches!(&kind, AssignmentKind::AssignIncr | AssignmentKind::AssignDecr) {
+					self.validate_type(exp_type, self.types.number(), value);
+					self.validate_type(var.type_, self.types.number(), variable);
+				}
+
 				self.validate_type(exp_type, var.type_, value);
 			}
 			StmtKind::Bring { source, identifier } => {

libs/wingc/src/type_check/class_fields_init.rs

@@ -1,5 +1,5 @@
 use crate::{
-	ast::{Reference, Stmt, StmtKind, Symbol},
+	ast::{AssignmentKind, Reference, Stmt, StmtKind, Symbol},
 	visit::{self, Visit},
 };
 
@@ -20,7 +20,11 @@ impl VisitClassInit {
 impl Visit<'_> for VisitClassInit {
 	fn visit_stmt(&mut self, node: &Stmt) {
 		match &node.kind {
-			StmtKind::Assignment { variable, value: _ } => match variable {
+			StmtKind::Assignment {
+				kind: AssignmentKind::Assign,
+				variable,
+				value: _,
+			} => match variable {
 				Reference::InstanceMember {
 					property,
 					object: _,

libs/wingc/src/visit.rs

@@ -170,7 +170,11 @@ where
 		StmtKind::Expression(expr) => {
 			v.visit_expr(&expr);
 		}
-		StmtKind::Assignment { variable, value } => {
+		StmtKind::Assignment {
+			kind: _,
+			variable,
+			value,
+		} => {
 			v.visit_reference(variable);
 			v.visit_expr(value);
 		}

tools/hangar/__snapshots__/test_corpus/valid/reassignment.w_compile_tf-aws.md

@@ -90,6 +90,11 @@ class $Root extends $stdlib.std.Resource {
     {((cond) => {if (!cond) throw new Error("assertion failed: x == 5")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(x,5)))};
     x = (x + 1);
     {((cond) => {if (!cond) throw new Error("assertion failed: x == 6")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(x,6)))};
+    let z = 1;
+    z += 2;
+    {((cond) => {if (!cond) throw new Error("assertion failed: z == 3")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(z,3)))};
+    z -= 1;
+    {((cond) => {if (!cond) throw new Error("assertion failed: z == 2")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(z,2)))};
     const r = new R(this,"R");
     (r.inc());
     {((cond) => {if (!cond) throw new Error("assertion failed: r.f == 2")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(r.f,2)))};