Rename parser dir to parse (#3178)

Continuing with #3070. Just a dir and file rename (mostly removing
prefixes, although for parse_tree_fuzzer and parse_tree_file_test I'm
dropping "tree" instead of "parse"). Everything in the parse dir should
be marked as a move.

toolchain/parse/handle_array_expression.cpp

@@ -0,0 +1,49 @@
+// 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/parse/context.h"
+#include "toolchain/parse/node_kind.h"
+#include "toolchain/parse/state.h"
+
+namespace Carbon::Parse {
+
+auto HandleArrayExpression(Context& context) -> void {
+  auto state = context.PopState();
+  state.state = State::ArrayExpressionSemi;
+  context.AddLeafNode(NodeKind::ArrayExpressionStart,
+                      context.ConsumeChecked(Lex::TokenKind::OpenSquareBracket),
+                      state.has_error);
+  context.PushState(state);
+  context.PushState(State::Expression);
+}
+
+auto HandleArrayExpressionSemi(Context& context) -> void {
+  auto state = context.PopState();
+  auto semi = context.ConsumeIf(Lex::TokenKind::Semi);
+  if (!semi) {
+    context.AddNode(NodeKind::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(NodeKind::ArrayExpressionSemi, *semi, state.subtree_start,
+                    state.has_error);
+  }
+  state.state = State::ArrayExpressionFinish;
+  context.PushState(state);
+  if (!context.PositionIs(Lex::TokenKind::CloseSquareBracket)) {
+    context.PushState(State::Expression);
+  }
+}
+
+auto HandleArrayExpressionFinish(Context& context) -> void {
+  auto state = context.PopState();
+  context.ConsumeAndAddCloseSymbol(*(Lex::TokenIterator(state.token)), state,
+                                   NodeKind::ArrayExpression);
+}
+
+}  // namespace Carbon::Parse