Emit UnaryOp expression.

This CL updates the WGSL generator to emit the UnaryOpExpression node.

Bug: tint:4
Change-Id: I54046b5238a45994f7a4ed27941bd22b0c75f836
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/17161
Reviewed-by: David Neto <dneto@google.com>

src/CMakeLists.txt

@@ -418,6 +418,7 @@ if(${TINT_BUILD_WGSL_WRITER})
     writer/wgsl/generator_impl_type_test.cc
     writer/wgsl/generator_impl_unary_derivative_test.cc
     writer/wgsl/generator_impl_unary_method_test.cc
+    writer/wgsl/generator_impl_unary_op_test.cc
     writer/wgsl/generator_impl_variable_test.cc
   )
 endif()

src/writer/wgsl/generator_impl.cc

@@ -46,6 +46,7 @@
 #include "src/ast/uint_literal.h"
 #include "src/ast/unary_derivative_expression.h"
 #include "src/ast/unary_method_expression.h"
+#include "src/ast/unary_op_expression.h"
 
 namespace tint {
 namespace writer {
@@ -152,6 +153,9 @@ bool GeneratorImpl::EmitExpression(ast::Expression* expr) {
   if (expr->IsUnaryMethod()) {
     return EmitUnaryMethod(expr->AsUnaryMethod());
   }
+  if (expr->IsUnaryOp()) {
+    return EmitUnaryOp(expr->AsUnaryOp());
+  }
 
   error_ = "unknown expression type";
   return false;
@@ -615,6 +619,26 @@ bool GeneratorImpl::EmitUnaryMethod(ast::UnaryMethodExpression* expr) {
   return true;
 }
 
+bool GeneratorImpl::EmitUnaryOp(ast::UnaryOpExpression* expr) {
+  switch (expr->op()) {
+    case ast::UnaryOp::kNot:
+      out_ << "!";
+      break;
+    case ast::UnaryOp::kNegation:
+      out_ << "-";
+      break;
+  }
+  out_ << "(";
+
+  if (!EmitExpression(expr->expr())) {
+    return false;
+  }
+
+  out_ << ")";
+
+  return true;
+}
+
 }  // namespace wgsl
 }  // namespace writer
 }  // namespace tint

src/writer/wgsl/generator_impl.h

@@ -134,6 +134,10 @@ class GeneratorImpl {
   /// @param expr the expression to emit
   /// @returns true if the expression was emitted
   bool EmitUnaryMethod(ast::UnaryMethodExpression* expr);
+  /// Handles a unary op expression
+  /// @param expr the expression to emit
+  /// @returns true if the expression was emitted
+  bool EmitUnaryOp(ast::UnaryOpExpression* expr);
   /// Handles generating a variable
   /// @param var the variable to generate
   /// @returns true if the variable was emitted

src/writer/wgsl/generator_impl_unary_op_test.cc

@@ -0,0 +1,56 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <memory>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "src/ast/identifier_expression.h"
+#include "src/ast/unary_op_expression.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+struct UnaryOpData {
+  const char* name;
+  ast::UnaryOp op;
+};
+inline std::ostream& operator<<(std::ostream& out, UnaryOpData data) {
+  out << data.op;
+  return out;
+}
+using UnaryOpTest = testing::TestWithParam<UnaryOpData>;
+TEST_P(UnaryOpTest, Emit) {
+  auto params = GetParam();
+
+  auto expr = std::make_unique<ast::IdentifierExpression>("expr");
+  ast::UnaryOpExpression op(params.op, std::move(expr));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitExpression(&op)) << g.error();
+  EXPECT_EQ(g.result(), std::string(params.name) + "(expr)");
+}
+INSTANTIATE_TEST_SUITE_P(GeneratorImplTest,
+                         UnaryOpTest,
+                         testing::Values(UnaryOpData{"!", ast::UnaryOp::kNot},
+                                         UnaryOpData{"-",
+                                                     ast::UnaryOp::kNegation}));
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint