Logical "!" operator.

munificent · munificent · commit dc4d8de07a68 · 2023-11-04T20:30:21.000-07:00
diff --git a/packages/betwixt/lib/src/parser.dart b/packages/betwixt/lib/src/parser.dart
@@ -237,7 +237,7 @@ class Parser {
   }
 
   Expr _unary() {
-    if (_match(TokenType.minus)) {
+    if (_match(TokenType.minus) || _match(TokenType.bang)) {
       var op = _previous;
       return UnaryExpr(op, _unary());
     }
diff --git a/packages/betwixt/lib/src/renderer.dart b/packages/betwixt/lib/src/renderer.dart
@@ -224,12 +224,20 @@ class Renderer
   Future<Object?> visitUnaryExpr(UnaryExpr expr) async {
     var operand = await expr.expression.accept(this);
     switch ((expr.op.type, operand)) {
+      case (TokenType.bang, bool operand):
+        return !operand;
+
+      case (TokenType.bang, _):
+        _reporter.report(expr.op.span,
+            'Operand to "!" must be a Boolean but was ${operand.runtimeType}.');
+        return null;
+
       case (TokenType.minus, num operand):
         return -operand;
 
       case (TokenType.minus, _):
         _reporter.report(expr.op.span,
-            'Cannot negate a value of type ${operand.runtimeType}.');
+            'Operand to "-" must be a number but was ${operand.runtimeType}.');
         return null;
 
       default:
diff --git a/packages/betwixt/lib/src/token.dart b/packages/betwixt/lib/src/token.dart
@@ -52,7 +52,6 @@ enum TokenType {
   comma,
   dot,
   equal,
-  // TODO: Implement.
   bang,
   minus,
   plus,
diff --git a/packages/betwixt/test/cases/arithmetic/negate_wrong_type.txt b/packages/betwixt/test/cases/arithmetic/negate_wrong_type.txt
@@ -1,6 +1,6 @@
 {{ -"wat" }}
 --- runtime errors
-line 1, column 4 of test: Cannot negate a value of type String.
+line 1, column 4 of test: Operand to "-" must be a number but was String.
   ╷
 1 │ {{ -"wat" }}
   │    ^
diff --git a/packages/betwixt/test/cases/logic/not.txt b/packages/betwixt/test/cases/logic/not.txt
@@ -0,0 +1,11 @@
+{{ !yes }}
+{{ !no }}
+{{ !!yes }}
+{{ !!!no }}
+--- output
+false
+true
+true
+true
+--- data
+{"yes": true, "no": false}
diff --git a/packages/betwixt/test/cases/logic/not_wrong_type.txt b/packages/betwixt/test/cases/logic/not_wrong_type.txt
@@ -0,0 +1,7 @@
+{{ !"wat" }}
+--- runtime errors
+line 1, column 4 of test: Operand to "!" must be a Boolean but was String.
+  ╷
+1 │ {{ !"wat" }}
+  │    ^
+  ╵

Original file line number	Diff line number	Diff line change
`@@ -237,7 +237,7 @@ class Parser {`
`237`	`237`	`}`
`238`	`238`
`239`	`239`	`Expr _unary() {`
`240`		`- if (_match(TokenType.minus)) {`
	`240`	`+ if (_match(TokenType.minus) \|\| _match(TokenType.bang)) {`
`241`	`241`	`var op = _previous;`
`242`	`242`	`return UnaryExpr(op, _unary());`
`243`	`243`	`}`
-Original file line number
+Diff line change
   comma,
   dot,
   equal,
 -  // TODO: Implement.
   bang,
   minus,
   plus,