Add source/cpp2decl.cpp

source/cpp2decl.cpp

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+//  Copyright (c) Herb Sutter
+//  SPDX-License-Identifier: CC-BY-NC-ND-4.0
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// ----
+
+// cpp2decl prints the declarations in a cpp2 file. For example, running on
+// regression-tests/pure2-types-inheritance.cpp2 (at commit 1764f0c) prints:
+//
+// Human                           : type
+// Human::speak                    : (this)
+// Human::operator=                : (move this)
+// N::Machine                      : type
+// N::Machine::operator=           : (out this, _: std::string)
+// N::Machine::work                : (this)
+// N::Machine::operator=           : (move this)
+// Cyborg                          : type
+// Cyborg::name                    : std::string
+// Cyborg::this                    : Human
+// Cyborg::address                 : std::string
+// Cyborg::this                    : N::Machine<(expression)>
+// Cyborg::operator=               : (out this, n: std::string)
+// Cyborg::speak                   : (this)
+// Cyborg::work                    : (this)
+// Cyborg::print                   : (this)
+// Cyborg::operator=               : (move this)
+// make_speak                      : (h: Human)
+// do_work                         : (m: N::Machine<(expression)>)
+// main                            : ()
+//
+// Declarations are printed one per line and their names are flattened, so that
+// the line for the `work` method on the `Machine` type in the `N` namespace
+// starts with `N::Machine::work`. This flattening is similar to how gron
+// (https://github.com/tomnomnom/gron) flattens JSON and has the same
+// motivation. Flattening combines well with classic, line-oriented, Unix-style
+// tools like diff, grep, sed and sort. Unlike the original C++2 source file,
+// which may have "N: namespace" and "Machine: type" on different lines,
+// sorting the lines of cpp2decl's output will not change its meaning.
+//
+// Many IDEs already have a "table of contents" view, but this command does not
+// require an IDE to provide a GUI or further context. For example, automated
+// tooling can combine cpp2decl, sort and diff to derive "what API changed
+// between two versions", similar to https://go.dev/api/go1.19.txt
+//
+// cpp2decl can also be used to get a quick overview of an unfamiliar corpus of
+// C++2 source code, and cpp2decl+grep can quickly answer ad hoc queries like
+// "show me all of the 'speak' methods implemented by cpp2 files in this
+// directory", without having to first import that project into an IDE or to
+// build (and keep up-to-date, e.g. when checking out different branches) a
+// code-search index.
+
+// ----
+
+// Build instructions: build cpp2decl.cpp just like building cppfront.cpp, per
+// the top-level README.md.
+
+// ----
+
+// TODO: a flag for writing to a file (a .cpp2decl file??) instead of always to
+// stdout. That would probably best start by refactoring cppfront.cpp.
+//
+// TODO: a flag for hiding private or anonymous-namespace names?
+//
+// TODO: a flag for hiding argument names (or replacing them with `_`)? Going
+// from `f(x: int)` to `f(y: int)` isn't actually an API change.
+//
+// TODO: fix the `(expression)` in `N::Machine<(expression)>`.
+//
+// TODO: also parse C++1 syntax, which is obviously easier said than done.
+//
+// TODO: paint the bikeshed about cpp2decl's output syntax.
+
+// ----
+
+// This file was formatted by clang-format (using its default options).
+
+// ----
+
+#include <cstdio>
+#include <iostream>
+#include <optional>
+#include <sstream>
+
+// TODO: is there a better header? We don't actually need semantic analysis.
+#include "sema.h"
+
+namespace cpp2 {
+
+namespace {
+
+auto do_declaration_name(std::ostream& out, declaration_node const& n)
+    -> size_t {
+  size_t num_printed = 0;
+  if (n.parent_declaration) {
+    num_printed = 2 + do_declaration_name(out, *n.parent_declaration);
+    out << "::";
+  }
+  std::string_view sv = std::string_view(*n.identifier->identifier);
+  out << sv;
+  return num_printed + sv.size();
+};
+
+auto do_parameters(std::ostream& out,
+                   parameter_declaration_list_node& n,
+                   passing_style default_passing_style) -> void {
+  out << "(";
+  bool first = true;
+  for (std::unique_ptr<parameter_declaration_node> const& pdn : n.parameters) {
+    if (!first) {
+      out << ", ";
+    }
+    std::string_view const& name = *pdn->name();
+    // TODO: print modifiers like "override".
+    if (passing_style ps = pdn->direction(); ps != default_passing_style) {
+      out << to_string_view(ps) << " ";
+    }
+    out << name;
+    if (name != "this") {
+      out << ": ";
+      if (pdn->declaration->is_object()) {
+        auto const& o =
+            std::get<declaration_node::an_object>(pdn->declaration->type);
+        for (auto const& q : o->pc_qualifiers) {
+          out << *q << " ";
+        }
+        out << pdn->declaration->object_type();
+      } else {
+        out << "???";
+      }
+    }
+    first = false;
+  }
+  out << ")";
+}
+
+auto do_function(std::ostream& out, function_type_node& n) -> void {
+  do_parameters(out, *n.parameters, passing_style::in);
+
+  switch (n.returns.index()) {
+    case function_type_node::empty: {
+      break;
+    }
+    case function_type_node::id: {
+      function_type_node::single_type_id const& sti =
+          std::get<function_type_node::id>(n.returns);
+      out << " -> ";
+      if (passing_style ps = sti.pass; ps != passing_style::move) {
+        out << to_string_view(ps) << " ";
+      }
+      out << sti.type->to_string();
+      break;
+    }
+    case function_type_node::list: {
+      std::unique_ptr<parameter_declaration_list_node>& pdln =
+          std::get<function_type_node::list>(n.returns);
+      out << " -> ";
+      do_parameters(out, *pdln, passing_style::out);
+      break;
+    }
+  }
+}
+
+auto do_declaration(std::ostream& out, declaration_node const& n) -> void {
+  if (!n.is_namespace()) {
+    size_t num_printed = do_declaration_name(out, n);
+    if (num_printed < 32) {
+      static const char* thirty_two_spaces = "                                ";
+      out << thirty_two_spaces + num_printed << ": ";
+    } else {
+      out << " : ";
+    }
+
+    switch (n.type.index()) {
+      case declaration_node::a_function: {
+        do_function(out, *std::get<declaration_node::a_function>(n.type));
+        break;
+      }
+      case declaration_node::an_object: {
+        auto const& o = std::get<declaration_node::an_object>(n.type);
+        for (auto const& q : o->pc_qualifiers) {
+          out << *q << " ";
+        }
+        out << n.object_type();
+        break;
+      }
+      case declaration_node::a_type: {
+        // TODO: print "@interface", "@polymorphic_base", "<I:int>", etc.
+        out << "type";
+        break;
+      }
+    }
+    out << "\n";
+  }
+
+  if (n.is_namespace() || n.is_type()) {
+    auto& c = std::get<statement_node::compound>(n.initializer->statement);
+    for (auto& s : c->statements) {
+      if (s->is_declaration()) {
+        auto& d = std::get<statement_node::declaration>(s->statement);
+        do_declaration(out, *d);
+      }
+    }
+  }
+}
+
+}  // namespace
+
+auto cmdline_processor::print(std::string_view s, int width) -> void {
+  if (width > 0) {
+    std::cout << std::setw(width) << std::left;
+  }
+  std::cout << s;
+}
+
+auto error_entry::print(auto& o, std::string const& file) const -> void {
+  o << file;
+  if (where.lineno > 0) {
+    o << "(" << (where.lineno);
+    if (where.colno >= 0) {
+      o << "," << where.colno;
+    }
+    o << ")";
+  }
+  o << ":";
+  if (internal) {
+    o << " internal compiler";
+  }
+  o << " error: " << msg << "\n";
+}
+
+class cpp2decl {
+  std::string sourcefile;
+  std::vector<error_entry> errors;
+
+  cpp2::source source;
+  cpp2::tokens tokens;
+  cpp2::parser parser;
+
+ public:
+  cpp2decl(std::string const& filename)
+      : sourcefile{filename}, source{errors}, tokens{errors}, parser{errors} {
+    if (!sourcefile.ends_with(".cpp2") && !sourcefile.ends_with(".h2")) {
+      errors.emplace_back(
+          source_position(-1, -1),
+          "source filename must end with .cpp2 or .h2: " + sourcefile);
+    } else if (!source.load(sourcefile)) {
+      if (errors.empty()) {
+        errors.emplace_back(source_position(-1, -1),
+                            "file not found: " + sourcefile);
+      }
+    } else {
+      tokens.lex(source.get_lines());
+      try {
+        for (auto const& [line, entry] : tokens.get_map()) {
+          if (!parser.parse(entry, tokens.get_generated())) {
+            errors.emplace_back(source_position(line, 0),
+                                "parse failed for section starting here", false,
+                                true);
+          }
+        }
+      } catch (std::runtime_error& e) {
+        errors.emplace_back(source_position(-1, -1), e.what());
+      }
+    }
+  }
+
+  auto run(std::ostream& out) -> void {
+    for (auto& section : tokens.get_map()) {
+      auto decls = parser.get_parse_tree_declarations_in_range(section.second);
+      for (auto const& decl : decls) {
+        do_declaration(out, *decl);
+      }
+    }
+  }
+
+  auto print_errors(std::ostream& out) -> void {
+    error_entry const* prev = {};
+    bool print_fallback_errors = true;
+    for (auto&& error : errors) {
+      if (!error.fallback) {
+        print_fallback_errors = false;
+      }
+      if (error.fallback && !print_fallback_errors) {
+        continue;
+      }
+      if (!prev || error != *prev) {
+        error.print(out, strip_path(sourcefile));
+      }
+      prev = &error;
+    }
+  }
+
+  auto had_no_errors() -> bool { return errors.empty(); }
+};
+
+}  // namespace cpp2
+
+auto main(int argc, char* argv[]) -> int {
+  cpp2::cmdline.set_args(argc, argv);
+  cpp2::cmdline.process_flags();
+  std::stringbuf str_buf;
+  std::ostream os(&str_buf);
+  int exit_status = EXIT_SUCCESS;
+  for (auto const& arg : cpp2::cmdline.arguments()) {
+    cpp2::cpp2decl c(arg.text);
+    c.run(os);
+    if (!c.had_no_errors()) {
+      c.print_errors(std::cerr);
+      exit_status = EXIT_FAILURE;
+    }
+  }
+  std::cout << str_buf.str();
+  return exit_status;
+}