Parser for array type. (#3075)

Co-authored-by: Farzana Ahmed Siddique <fasiddique@google.com>

toolchain/parser/parser_handle_array_expression.cpp

@@ -0,0 +1,50 @@
+// 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 "toolchain/lexer/token_kind.h"
+#include "toolchain/lexer/tokenized_buffer.h"
+#include "toolchain/parser/parse_node_kind.h"
+#include "toolchain/parser/parser_context.h"
+#include "toolchain/parser/parser_state.h"
+
+namespace Carbon {
+
+auto ParserHandleArrayExpression(ParserContext& context) -> void {
+  auto state = context.PopState();
+  state.state = ParserState::ArrayExpressionSemi;
+  context.AddLeafNode(ParseNodeKind::ArrayExpressionStart,
+                      context.ConsumeChecked(TokenKind::OpenSquareBracket),
+                      state.has_error);
+  context.PushState(state);
+  context.PushState(ParserState::Expression);
+}
+
+auto ParserHandleArrayExpressionSemi(ParserContext& context) -> void {
+  auto state = context.PopState();
+  auto semi = context.ConsumeIf(TokenKind::Semi);
+  if (!semi) {
+    context.AddNode(ParseNodeKind::ArrayExpressionSemi, *context.position(),
+                    state.subtree_start, true);
+    CARBON_DIAGNOSTIC(ExpectedArraySemi, Error, "Expected `;` in array type.");
+    context.emitter().Emit(*context.position(), ExpectedArraySemi);
+    state.has_error = true;
+  } else {
+    context.AddNode(ParseNodeKind::ArrayExpressionSemi, *semi,
+                    state.subtree_start, state.has_error);
+  }
+  state.state = ParserState::ArrayExpressionFinish;
+  context.PushState(state);
+  if (!context.PositionIs(TokenKind::CloseSquareBracket)) {
+    context.PushState(ParserState::Expression);
+  }
+}
+
+auto ParserHandleArrayExpressionFinish(ParserContext& context) -> void {
+  auto state = context.PopState();
+  context.ConsumeAndAddCloseSymbol(
+      *(TokenizedBuffer::TokenIterator(state.token)), state,
+      ParseNodeKind::ArrayExpression);
+}
+
+}  // namespace Carbon