Restructure handling of paren expressions (#417)

* Move nontrivial logic out of `parser.ypp` into `FieldList`, rename it to `ParenContents`, make it a class, and add tests * Use a `FieldInitializer` struct instead of `std::pair<std::string, Expression*>` to represent the fields of a tuple
2026-10-04 19:01:05 +01:00 · 2021-04-05 10:49:25 -07:00
parent 98a6477233
commit 80f035874d
9 changed files with 251 additions and 105 deletions
@@ -0,0 +1,113 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include "executable_semantics/syntax/paren_contents.h"
+
+#include "gtest/gtest.h"
+
+namespace Carbon {
+namespace {
+
+TEST(ParenContentsTest, EmptyAsExpression) {
+  ParenContents contents;
+  Expression* expression = contents.AsExpression(/*line_num=*/1);
+  EXPECT_EQ(expression->line_num, 1);
+  ASSERT_EQ(expression->tag, ExpressionKind::Tuple);
+  EXPECT_EQ(expression->u.tuple.fields->size(), 0);
+}
+
+TEST(ParenContentsTest, EmptyAsTuple) {
+  ParenContents contents;
+  Expression* tuple = contents.AsTuple(/*line_num=*/1);
+  EXPECT_EQ(tuple->line_num, 1);
+  ASSERT_EQ(tuple->tag, ExpressionKind::Tuple);
+  EXPECT_EQ(tuple->u.tuple.fields->size(), 0);
+}
+
+TEST(ParenContentsTest, UnaryNoCommaAsExpression) {
+  // Equivalent to a code fragment like
+  // ```
+  // (
+  //   42
+  // )
+  // ```
+  ParenContents contents({{.expression = MakeInt(/*line_num=*/2, 42)}},
+                         ParenContents::HasTrailingComma::No);
+
+  Expression* expression = contents.AsExpression(/*line_num=*/1);
+  EXPECT_EQ(expression->line_num, 2);
+  ASSERT_EQ(expression->tag, ExpressionKind::Integer);
+}
+
+TEST(ParenContentsTest, UnaryNoCommaAsTuple) {
+  ParenContents contents({{.expression = MakeInt(/*line_num=*/2, 42)}},
+                         ParenContents::HasTrailingComma::No);
+
+  Expression* tuple = contents.AsTuple(/*line_num=*/1);
+  EXPECT_EQ(tuple->line_num, 1);
+  ASSERT_EQ(tuple->tag, ExpressionKind::Tuple);
+  std::vector<std::pair<std::string, Expression*>> fields =
+      *tuple->u.tuple.fields;
+  ASSERT_EQ(fields.size(), 1);
+  EXPECT_EQ(fields[0].second->tag, ExpressionKind::Integer);
+}
+
+TEST(ParenContentsTest, UnaryWithCommaAsExpression) {
+  ParenContents contents({{.expression = MakeInt(/*line_num=*/2, 42)}},
+                         ParenContents::HasTrailingComma::Yes);
+
+  Expression* expression = contents.AsExpression(/*line_num=*/1);
+  EXPECT_EQ(expression->line_num, 1);
+  ASSERT_EQ(expression->tag, ExpressionKind::Tuple);
+  std::vector<std::pair<std::string, Expression*>> fields =
+      *expression->u.tuple.fields;
+  ASSERT_EQ(fields.size(), 1);
+  EXPECT_EQ(fields[0].second->tag, ExpressionKind::Integer);
+}
+
+TEST(ParenContentsTest, UnaryWithCommaAsTuple) {
+  ParenContents contents({{.expression = MakeInt(/*line_num=*/2, 42)}},
+                         ParenContents::HasTrailingComma::Yes);
+
+  Expression* tuple = contents.AsTuple(/*line_num=*/1);
+  EXPECT_EQ(tuple->line_num, 1);
+  ASSERT_EQ(tuple->tag, ExpressionKind::Tuple);
+  std::vector<std::pair<std::string, Expression*>> fields =
+      *tuple->u.tuple.fields;
+  ASSERT_EQ(fields.size(), 1);
+  EXPECT_EQ(fields[0].second->tag, ExpressionKind::Integer);
+}
+
+TEST(ParenContentsTest, BinaryAsExpression) {
+  ParenContents contents({{.expression = MakeInt(/*line_num=*/2, 42)},
+                          {.expression = MakeInt(/*line_num=*/3, 42)}},
+                         ParenContents::HasTrailingComma::Yes);
+
+  Expression* expression = contents.AsExpression(/*line_num=*/1);
+  EXPECT_EQ(expression->line_num, 1);
+  ASSERT_EQ(expression->tag, ExpressionKind::Tuple);
+  std::vector<std::pair<std::string, Expression*>> fields =
+      *expression->u.tuple.fields;
+  ASSERT_EQ(fields.size(), 2);
+  EXPECT_EQ(fields[0].second->tag, ExpressionKind::Integer);
+  EXPECT_EQ(fields[1].second->tag, ExpressionKind::Integer);
+}
+
+TEST(ParenContentsTest, BinaryAsTuple) {
+  ParenContents contents({{.expression = MakeInt(/*line_num=*/2, 42)},
+                          {.expression = MakeInt(/*line_num=*/3, 42)}},
+                         ParenContents::HasTrailingComma::Yes);
+
+  Expression* tuple = contents.AsTuple(/*line_num=*/1);
+  EXPECT_EQ(tuple->line_num, 1);
+  ASSERT_EQ(tuple->tag, ExpressionKind::Tuple);
+  std::vector<std::pair<std::string, Expression*>> fields =
+      *tuple->u.tuple.fields;
+  ASSERT_EQ(fields.size(), 2);
+  EXPECT_EQ(fields[0].second->tag, ExpressionKind::Integer);
+  EXPECT_EQ(fields[1].second->tag, ExpressionKind::Integer);
+}
+
+}  // namespace
+}  // namespace Carbon