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/node_kind.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/parse/node_kind.h"
+
+#include "common/check.h"
+
+namespace Carbon::Parse {
+
+CARBON_DEFINE_ENUM_CLASS_NAMES(NodeKind) = {
+#define CARBON_PARSE_NODE_KIND(Name) CARBON_ENUM_CLASS_NAME_STRING(Name)
+#include "toolchain/parse/node_kind.def"
+};
+
+auto NodeKind::has_bracket() const -> bool {
+  static constexpr bool HasBracket[] = {
+#define CARBON_PARSE_NODE_KIND_BRACKET(...) true,
+#define CARBON_PARSE_NODE_KIND_CHILD_COUNT(...) false,
+#include "toolchain/parse/node_kind.def"
+  };
+  return HasBracket[AsInt()];
+}
+
+auto NodeKind::bracket() const -> NodeKind {
+  // Nodes are never self-bracketed, so we use that for nodes that instead set
+  // child_count.
+  static constexpr NodeKind Bracket[] = {
+#define CARBON_PARSE_NODE_KIND_BRACKET(Name, BracketName) NodeKind::BracketName,
+#define CARBON_PARSE_NODE_KIND_CHILD_COUNT(Name, ...) NodeKind::Name,
+#include "toolchain/parse/node_kind.def"
+  };
+  auto bracket = Bracket[AsInt()];
+  CARBON_CHECK(bracket != *this) << *this;
+  return bracket;
+}
+
+auto NodeKind::child_count() const -> int32_t {
+  static constexpr int32_t ChildCount[] = {
+#define CARBON_PARSE_NODE_KIND_BRACKET(...) -1,
+#define CARBON_PARSE_NODE_KIND_CHILD_COUNT(Name, Size) Size,
+#include "toolchain/parse/node_kind.def"
+  };
+  auto child_count = ChildCount[AsInt()];
+  CARBON_CHECK(child_count >= 0) << *this;
+  return child_count;
+}
+
+}  // namespace Carbon::Parse