Add skeletal format subcommand. (#4383)

This extracts out the SourceBuffer handling of `-` in order to trivially share it. Note this still has a number of TODOs, it's just setting up the essential subcommand infrastructure, with some tests demonstrating that it at least does something.
2026-10-04 22:02:52 +01:00 · 2024-10-09 17:33:29 +00:00
parent 33954d1f20
commit 434173b016
15 changed files with 306 additions and 7 deletions
@@ -0,0 +1,99 @@
+// 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/driver/format_subcommand.h"
+
+#include <string>
+
+#include "toolchain/base/value_store.h"
+#include "toolchain/diagnostics/diagnostic_consumer.h"
+#include "toolchain/format/format.h"
+#include "toolchain/lex/lex.h"
+#include "toolchain/source/source_buffer.h"
+
+namespace Carbon {
+
+constexpr CommandLine::CommandInfo FormatOptions::Info = {
+    .name = "format",
+    .help = R"""(
+Format Carbon source code.
+)""",
+};
+
+auto FormatOptions::Build(CommandLine::CommandBuilder& b) -> void {
+  b.AddStringPositionalArg(
+      {
+          .name = "FILE",
+          .help = R"""(
+The input Carbon source file(s) to format.
+)""",
+      },
+      [&](auto& arg_b) {
+        arg_b.Required(true);
+        arg_b.Append(&input_filenames);
+      });
+  b.AddStringOption(
+      {
+          .name = "output",
+          .value_name = "FILE",
+          .help = R"""(
+The output filename for formatted output.
+
+By default, the input file is formatted. Passing `--output=-` will write the
+output to stdout.
+
+Not valid when multiple files are passed for formatting.
+)""",
+      },
+      [&](auto& arg_b) { arg_b.Set(&output_filename); });
+}
+
+auto FormatSubcommand::Run(DriverEnv& driver_env) -> DriverResult {
+  DriverResult result = {.success = true};
+  if (options_.input_filenames.size() > 1 &&
+      !options_.output_filename.empty()) {
+    driver_env.error_stream << "error: cannot format multiple input files when "
+                               "--output is set\n";
+    result.success = false;
+    return result;
+  }
+
+  auto mark_per_file_error = [&]() {
+    result.success = false;
+    result.per_file_success.back().second = false;
+  };
+
+  StreamDiagnosticConsumer consumer(driver_env.error_stream);
+  for (auto& f : options_.input_filenames) {
+    // Push a result, which we'll update on failure.
+    result.per_file_success.push_back({f.str(), true});
+
+    // TODO: Consider refactoring this for sharing with compile.
+    // TODO: Decide what to do with `-` when there are multiple arguments.
+    auto source = SourceBuffer::MakeFromFileOrStdin(driver_env.fs, f, consumer);
+    if (!source) {
+      mark_per_file_error();
+      continue;
+    }
+    SharedValueStores value_stores;
+    auto tokens = Lex::Lex(value_stores, *source, consumer);
+
+    std::string buffer_str;
+    llvm::raw_string_ostream buffer(buffer_str);
+
+    if (Format::Format(tokens, buffer)) {
+      // TODO: Figure out a multi-file output setup that supports good
+      // multi-file testing.
+      // TODO: Use --output values (and default to overwrite).
+      driver_env.output_stream << buffer_str;
+    } else {
+      mark_per_file_error();
+      driver_env.output_stream << source->text();
+    }
+  }
+
+  return result;
+}
+
+}  // namespace Carbon