Add support for parsing unary operations (#2538)

pkg/sass-parser/CHANGELOG.md

@@ -12,6 +12,8 @@
 
 * Add support for parsing the `supports()` function in `@import` modifiers.
 
+* Add support for parsing unary operation expressions.
+
 ## 0.4.15
 
 * Add support for parsing list expressions.

pkg/sass-parser/lib/index.ts

@@ -248,6 +248,11 @@ export {
   StaticImportProps,
   StaticImportRaws,
 } from './src/static-import';
+export {
+  UnaryOperationExpression,
+  UnaryOperationExpressionProps,
+  UnaryOperationExpressionRaws,
+} from './src/expression/unary-operation';
 
 /** Options that can be passed to the Sass parsers to control their behavior. */
 export type SassParserOptions = Pick<postcss.ProcessOptions, 'from' | 'map'>;

pkg/sass-parser/lib/src/expression/__snapshots__/unary-operation.test.ts.snap

@@ -0,0 +1,18 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`a unary operation toJSON 1`] = `
+{
+  "inputs": [
+    {
+      "css": "@#{+foo}",
+      "hasBOM": false,
+      "id": "<input css _____>",
+    },
+  ],
+  "operand": <foo>,
+  "operator": "+",
+  "raws": {},
+  "sassType": "unary-operation",
+  "source": <1:4-1:8 in 0>,
+}
+`;

pkg/sass-parser/lib/src/expression/convert.ts

@@ -20,6 +20,7 @@ import {NumberExpression} from './number';
 import {ParenthesizedExpression} from './parenthesized';
 import {SelectorExpression} from './selector';
 import {StringExpression} from './string';
+import {UnaryOperationExpression} from './unary-operation';
 
 /** The visitor to use to convert internal Sass nodes to JS. */
 const visitor = sassInternal.createExpressionVisitor<AnyExpression>({
@@ -52,6 +53,8 @@ const visitor = sassInternal.createExpressionVisitor<AnyExpression>({
       ]),
       source: new LazySource(inner),
     }),
+  visitUnaryOperationExpression: inner =>
+    new UnaryOperationExpression(undefined, inner),
 });
 
 /** Converts an internal expression AST node into an external one. */

pkg/sass-parser/lib/src/expression/from-props.ts

@@ -15,11 +15,13 @@ import {NullExpression} from './null';
 import {NumberExpression} from './number';
 import {ParenthesizedExpression} from './parenthesized';
 import {StringExpression} from './string';
+import {UnaryOperationExpression} from './unary-operation';
 
 /** Constructs an expression from {@link ExpressionProps}. */
 export function fromProps(props: ExpressionProps): AnyExpression {
   if ('text' in props) return new StringExpression(props);
   if ('left' in props) return new BinaryOperationExpression(props);
+  if ('operand' in props) return new UnaryOperationExpression(props);
   if ('separator' in props) return new ListExpression(props);
   if ('nodes' in props) return new MapExpression(props);
   if ('inParens' in props) return new ParenthesizedExpression(props);

pkg/sass-parser/lib/src/expression/index.ts

@@ -24,6 +24,10 @@ import {
 } from './parenthesized';
 import type {SelectorExpression} from './selector';
 import type {StringExpression, StringExpressionProps} from './string';
+import type {
+  UnaryOperationExpression,
+  UnaryOperationExpressionProps,
+} from './unary-operation';
 
 /**
  * The union type of all Sass expressions.
@@ -42,7 +46,8 @@ export type AnyExpression =
   | NumberExpression
   | ParenthesizedExpression
   | SelectorExpression
-  | StringExpression;
+  | StringExpression
+  | UnaryOperationExpression;
 
 /**
  * Sass expression types.
@@ -61,7 +66,8 @@ export type ExpressionType =
   | 'number'
   | 'parenthesized'
   | 'selector-expr'
-  | 'string';
+  | 'string'
+  | 'unary-operation';
 
 /**
  * The union type of all properties that can be used to construct Sass
@@ -80,7 +86,8 @@ export type ExpressionProps =
   | NullExpressionProps
   | NumberExpressionProps
   | ParenthesizedExpressionProps
-  | StringExpressionProps;
+  | StringExpressionProps
+  | UnaryOperationExpressionProps;
 
 /**
  * The superclass of Sass expression nodes.

pkg/sass-parser/lib/src/expression/unary-operation.test.ts

@@ -0,0 +1,269 @@
+// Copyright 2025 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+import {StringExpression, UnaryOperationExpression} from '../..';
+import * as utils from '../../../test/utils';
+
+describe('a unary operation', () => {
+  let node: UnaryOperationExpression;
+  function describeNode(
+    description: string,
+    create: () => UnaryOperationExpression,
+  ): void {
+    describe(description, () => {
+      beforeEach(() => void (node = create()));
+
+      it('has sassType unary-operation', () =>
+        expect(node.sassType).toBe('unary-operation'));
+
+      it('has an operator', () => expect(node.operator).toBe('+'));
+
+      it('has an operand', () =>
+        expect(node).toHaveStringExpression('operand', 'foo'));
+    });
+  }
+
+  describeNode('parsed', () => utils.parseExpression('+foo'));
+
+  describeNode(
+    'constructed manually',
+    () =>
+      new UnaryOperationExpression({
+        operator: '+',
+        operand: {text: 'foo'},
+      }),
+  );
+
+  describeNode('constructed from ExpressionProps', () =>
+    utils.fromExpressionProps({
+      operator: '+',
+      operand: {text: 'foo'},
+    }),
+  );
+
+  describe('assigned new', () => {
+    beforeEach(() => void (node = utils.parseExpression('+foo')));
+
+    it('operator', () => {
+      node.operator = 'not';
+      expect(node.operator).toBe('not');
+    });
+
+    describe('operand', () => {
+      it("removes the old operand's parent", () => {
+        const oldOperand = node.operand;
+        node.operand = {text: 'zip'};
+        expect(oldOperand.parent).toBeUndefined();
+      });
+
+      it('assigns operand explicitly', () => {
+        const operand = new StringExpression({text: 'zip'});
+        node.operand = operand;
+        expect(node.operand).toBe(operand);
+        expect(node.operand.parent).toBe(node);
+        expect(node).toHaveStringExpression('operand', 'zip');
+      });
+
+      it('assigns operand as ExpressionProps', () => {
+        node.operand = {text: 'zip'};
+        expect(node).toHaveStringExpression('operand', 'zip');
+      });
+    });
+  });
+
+  describe('stringifies', () => {
+    describe('plus', () => {
+      describe('with an identifier', () => {
+        beforeEach(
+          () =>
+            void (node = new UnaryOperationExpression({
+              operator: '+',
+              operand: {text: 'foo'},
+            })),
+        );
+
+        it('without raws', () => expect(node.toString()).toBe('+foo'));
+
+        it('with between', () => {
+          node.raws.between = '/**/';
+          expect(node.toString()).toBe('+/**/foo');
+        });
+      });
+
+      describe('with a number', () => {
+        beforeEach(
+          () =>
+            void (node = new UnaryOperationExpression({
+              operator: '+',
+              operand: {value: 0},
+            })),
+        );
+
+        it('without raws', () => expect(node.toString()).toBe('+ 0'));
+
+        it('with between', () => {
+          node.raws.between = '/**/';
+          expect(node.toString()).toBe('+/**/0');
+        });
+      });
+    });
+
+    describe('not', () => {
+      beforeEach(
+        () =>
+          void (node = new UnaryOperationExpression({
+            operator: 'not',
+            operand: {text: 'foo'},
+          })),
+      );
+
+      it('without raws', () => expect(node.toString()).toBe('not foo'));
+
+      it('with between', () => {
+        node.raws.between = '/**/';
+        expect(node.toString()).toBe('not/**/foo');
+      });
+    });
+
+    describe('minus', () => {
+      describe('with an identifier', () => {
+        beforeEach(
+          () =>
+            void (node = new UnaryOperationExpression({
+              operator: '-',
+              operand: {text: 'foo'},
+            })),
+        );
+
+        it('without raws', () => expect(node.toString()).toBe('- foo'));
+
+        it('with between', () => {
+          node.raws.between = '/**/';
+          expect(node.toString()).toBe('-/**/foo');
+        });
+      });
+
+      describe('with a number', () => {
+        beforeEach(
+          () =>
+            void (node = new UnaryOperationExpression({
+              operator: '-',
+              operand: {value: 0},
+            })),
+        );
+
+        it('without raws', () => expect(node.toString()).toBe('- 0'));
+
+        it('with between', () => {
+          node.raws.between = '/**/';
+          expect(node.toString()).toBe('-/**/0');
+        });
+      });
+
+      describe('with a function call', () => {
+        beforeEach(
+          () =>
+            void (node = new UnaryOperationExpression({
+              operator: '-',
+              operand: {name: 'foo', arguments: []},
+            })),
+        );
+
+        it('without raws', () => expect(node.toString()).toBe('- foo()'));
+
+        it('with between', () => {
+          node.raws.between = '/**/';
+          expect(node.toString()).toBe('-/**/foo()');
+        });
+      });
+
+      describe('with a parenthesized expression', () => {
+        beforeEach(
+          () =>
+            void (node = new UnaryOperationExpression({
+              operator: '-',
+              operand: {inParens: {text: 'foo'}},
+            })),
+        );
+
+        it('without raws', () => expect(node.toString()).toBe('-(foo)'));
+
+        it('with between', () => {
+          node.raws.between = '/**/';
+          expect(node.toString()).toBe('-/**/(foo)');
+        });
+      });
+    });
+  });
+
+  describe('clone', () => {
+    let original: UnaryOperationExpression;
+    beforeEach(() => {
+      original = utils.parseExpression('+foo');
+      // TODO: remove this once raws are properly parsed
+      original.raws.between = '  ';
+    });
+
+    describe('with no overrides', () => {
+      let clone: UnaryOperationExpression;
+      beforeEach(() => void (clone = original.clone()));
+
+      describe('has the same properties:', () => {
+        it('operator', () => expect(clone.operator).toBe('+'));
+
+        it('operand', () =>
+          expect(clone).toHaveStringExpression('operand', 'foo'));
+
+        it('raws', () => expect(clone.raws).toEqual({between: '  '}));
+
+        it('source', () => expect(clone.source).toBe(original.source));
+      });
+
+      describe('creates a new', () => {
+        it('self', () => expect(clone).not.toBe(original));
+
+        for (const attr of ['operand', 'raws'] as const) {
+          it(attr, () => expect(clone[attr]).not.toBe(original[attr]));
+        }
+      });
+    });
+
+    describe('overrides', () => {
+      describe('operator', () => {
+        it('defined', () =>
+          expect(original.clone({operator: '-'}).operator).toBe('-'));
+
+        it('undefined', () =>
+          expect(original.clone({operator: undefined}).operator).toBe('+'));
+      });
+
+      describe('operand', () => {
+        it('defined', () =>
+          expect(
+            original.clone({operand: {text: 'zip'}}),
+          ).toHaveStringExpression('operand', 'zip'));
+
+        it('undefined', () =>
+          expect(original.clone({operand: undefined})).toHaveStringExpression(
+            'operand',
+            'foo',
+          ));
+      });
+
+      describe('raws', () => {
+        it('defined', () =>
+          expect(original.clone({raws: {between: '/**/'}}).raws).toEqual({
+            between: '/**/',
+          }));
+
+        it('undefined', () =>
+          expect(original.clone({raws: undefined}).raws).toEqual({
+            between: '  ',
+          }));
+      });
+    });
+  });
+
+  it('toJSON', () => expect(utils.parseExpression('+foo')).toMatchSnapshot());
+});