Feat/implement tag

.clang-format

@@ -1 +1 @@
-InsertNewlineAtEOF: true
+InsertNewlineAtEOF: true

CMakeLists.txt

@@ -1,56 +1,51 @@
 cmake_minimum_required(VERSION 3.8.2)
 
-#Set a name and a version number for your project:
-    project(cpp - project - template VERSION 0.0.1 LANGUAGES CXX)
-
-        set(CMAKE_AR / usr / bin / ar)
-
-#Enable C language
-            enable_language(C)
-
-#this needs to be in the top level CMakeLists.txt to enable tests
-                include(CTest)
-
-                    set(BOOST_ENABLE_CMAKE ON) set(Boost_CMAKE_CXX_STANDARD 17) set(
-                        CMAKE_CXX_STANDARD 17) set(CMAKE_CXX_STANDARD_REQUIRED
-                                                       ON)
-
-                        set(BOOST_INCLUDE_LIBRARIES iostreams uuid algorithm)
-
-                            include(FetchContent) FetchContent_Declare(
-                                Boost GIT_REPOSITORY
-                                    https : // github.com/boostorg/boost.git
-                                GIT_TAG boost -
-                                1.83.0 GIT_SHALLOW
-                                    TRUE) FetchContent_MakeAvailable(Boost)
-
-#compile the library
-                                add_subdirectory(src)
-
-#compile the application
-                                    add_subdirectory(app)
-
-#optionally add doxygen target to generate documentation
-                                        option(BUILD_DOCS
-                                               "Enable building of "
-                                               "documentation (requires "
-                                               "Doxygen)" OFF) if (BUILD_DOCS)
-                                            find_package(Doxygen REQUIRED) set(
-                                                DOXYGEN_EXCLUDE_PATTERNS
-                                                "${CMAKE_SOURCE_DIR}/ext/*")
-                                                doxygen_add_docs(
-                                                    doxygen ${
-                                                        CMAKE_SOURCE_DIR} WORKING_DIRECTORY
-                                                        ${CMAKE_CURRENT_BINARY_DIR})
-                                                    endif()
-
-#compile the tests
-                                                        option(BUILD_TESTS
-                                                               "Enable "
-                                                               "building of "
-                                                               "documentation "
-                                                               "(requires "
-                                                               "Doxygen"
-                                                               ")" OFF) if (BUILD_TESTS)
-                                                            add_subdirectory(
-                                                                tests) endif()
+# Set a name and a version number for your project:
+project(
+  cpp-project-template
+  VERSION 0.0.1
+  LANGUAGES CXX)
+
+set(CMAKE_AR /usr/bin/ar)
+
+# Enable C language
+enable_language(C)
+
+# this needs to be in the top level CMakeLists.txt to enable tests
+include(CTest)
+
+set(BOOST_ENABLE_CMAKE ON)
+set(Boost_CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+set(BOOST_INCLUDE_LIBRARIES iostreams uuid algorithm)
+
+include(FetchContent)
+FetchContent_Declare(
+  Boost
+  GIT_REPOSITORY https://github.com/boostorg/boost.git
+  GIT_TAG boost-1.83.0
+  GIT_SHALLOW TRUE)
+FetchContent_MakeAvailable(Boost)
+
+# compile the library
+add_subdirectory(src)
+
+# compile the application
+add_subdirectory(app)
+
+# optionally add doxygen target to generate documentation
+option(BUILD_DOCS "Enable building of documentation (requires Doxygen)" OFF)
+if(BUILD_DOCS)
+  find_package(Doxygen REQUIRED)
+  set(DOXYGEN_EXCLUDE_PATTERNS "${CMAKE_SOURCE_DIR}/ext/*")
+  doxygen_add_docs(doxygen ${CMAKE_SOURCE_DIR}
+                   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+endif()
+
+# compile the tests
+option(BUILD_TESTS "Enable building of documentation (requires Doxygen)" OFF)
+if(BUILD_TESTS)
+  add_subdirectory(tests)
+endif()

app/gyt.cpp

@@ -5,6 +5,7 @@
 #include "commands/log.h"
 #include "commands/ls-tree.h"
 #include "commands/show-ref.h"
+#include "commands/tag.h"
 #include <iostream>
 #include <string>
 #include <vector>
@@ -33,6 +34,8 @@ int main(int argc, char **argv) {
     commands::checkout(args);
   } else if (command == "show-ref") {
     commands::showref(args);
+  } else if (command == "tag") {
+    commands::tag(args);
   } else {
     std::cerr << "Unknown command: " << command << "\n";
     return -1;

doc/case studies/Singleton.md

@@ -0,0 +1,10 @@
+# Parser and singleton
+
+`TagParser` is an example of a singleton class.
+It was largely adapted from: https://stackoverflow.com/questions/75249277/is-singleton-with-static-unique-ptr-a-good-practice
+
+It stores a reference of itself as a static member. The constructor constructs and sets the CmdLine arguments.
+
+Some learning points:
+- CmdLine, Arg classes has no default constructor, so they have to be constructed during the construction of `TagParser`, not after.
+- Using a `static` reference of itself.

include/commands/tag.h

@@ -0,0 +1,10 @@
+#ifndef TAG_H
+#define TAG_H
+
+#include <string>
+#include <vector>
+namespace commands {
+void tag(std::vector<std::string> &args);
+} // namespace commands
+
+#endif // TAG_H

include/parsers/TagParser.h

@@ -0,0 +1,30 @@
+#ifndef TAGPARSER_H
+#define TAGPARSER_H
+
+#include "tclap/CmdLine.h"
+#include <string>
+#include <vector>
+
+class TagParser {
+public:
+  static TagParser &get();
+  void parse(std::vector<std::string> &args);
+  std::string getTag();
+  bool isCommitSet() const;
+  std::string getCommit();
+
+private:
+  // hides constructors to avoid accidental instantiation
+  TagParser();
+  TagParser(const TagParser &) = delete;
+  TagParser &operator=(const TagParser &) = delete;
+  TagParser(TagParser &&) = delete;
+  TagParser &operator=(TagParser &&) = delete;
+  ~TagParser() = default;
+  // data members
+  TCLAP::CmdLine cmd;
+  TCLAP::UnlabeledValueArg<std::string> tagArg;
+  TCLAP::UnlabeledValueArg<std::string> commitArg;
+};
+
+#endif // TAGPARSER_H

include/repository.h

@@ -9,7 +9,7 @@ namespace fs = std::filesystem;
 class GitRepository {
 public:
   GitRepository(fs::path worktree, fs::path gitdir);
-  GitRepository(std::string path, bool force = false);
+  GitRepository(const std::string &path, bool force = false);
 
   static std::optional<GitRepository> find(const fs::path &path = fs::path("."),
                                            bool required = true);

include/util.h

@@ -16,4 +16,5 @@ fs::perms get_unix_permissions(int mode);
 std::string remove_file_prefix(const fs::path &path,
                                const fs::path &repo_prefix);
 std::string resolve_ref(const fs::path &ref_path, GitRepository &repo);
+fs::path get_commit_path(const std::string &sha);
 #endif // UTIL_H

run.sh

@@ -1,33 +1,31 @@
-#!/ bin / bash
-set - e
+#!/bin/bash
+set -e
 
 #Set the default build type to Debug if no environment is specified
-          BUILD_TYPE = ${BUILD_TYPE : -Debug}
+BUILD_TYPE=${BUILD_TYPE:-Debug}
 
 #If the environment is specified as "prod", set the build type to Release
-if["$1" == "-p"];
-then BUILD_TYPE = Release fi
+if [ "$1" == "-p" ];
+then
+    BUILD_TYPE=Release 
+fi
 
 #remove old build if any
-    if[-f "app/gyt"];
-then rm -
-    rf app / gyt fi
+if [ -f "app/gyt" ];
+then 
+    rm -rf app/gyt 
+fi
 
 #Print the selected build type
-             echo "Selected build type: $BUILD_TYPE" echo
-                  "Building the project... This will take a while to install "
-                  "dependencies for the first time."
+echo "Selected build type: $BUILD_TYPE" 
+echo "Building the project... This will take a while to install dependencies for the first time."
 
 #Run CMake with the selected build type
-             cmake..-
-    DCMAKE_BUILD_TYPE = $BUILD_TYPE - DCMAKE_EXPORT_COMPILE_COMMANDS =
-                            1 -
-                            G Ninja
+cmake .. -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -G Ninja
 
 #Build the project
-                                    ninja
+ninja
 
 #symlink - so I can run it like gyt[arguments....]
-                                        sudo rm /
-                                usr / local / bin / gyt sudo ln -
-                            s "$(pwd)/app/gyt" / usr / local / bin / gyt
+sudo rm /usr/local/bin/gyt 
+sudo ln -s "$(pwd)/app/gyt" /usr/local/bin/gyt

src/CMakeLists.txt

@@ -24,8 +24,14 @@ target_link_libraries(object PRIVATE repository boost_libraries)
 target_include_directories(object PUBLIC ../include)
 target_compile_features(object PUBLIC cxx_std_17)
 
+file(GLOB PARSER_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/parsers/*.cpp")
+add_library(parsers ${PARSER_SOURCES})
+target_link_libraries(parsers PRIVATE repository object boost_libraries)
+target_include_directories(parsers PUBLIC ../include)
+target_compile_features(parsers PUBLIC cxx_std_17)
+
 file(GLOB COMMANDS_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/commands/*.cpp")
 add_library(commands ${COMMANDS_SOURCES})
-target_link_libraries(commands PRIVATE repository object boost_libraries)
+target_link_libraries(commands PRIVATE parsers repository object boost_libraries)
 target_include_directories(commands PUBLIC ../include)
 target_compile_features(commands PUBLIC cxx_std_17)

src/commands/tag.cpp

@@ -0,0 +1,36 @@
+#include "commands/tag.h"
+#include "object.h"
+#include "parsers/TagParser.h"
+#include "repository.h"
+#include "util.h"
+#include <optional>
+
+namespace commands {
+void tag(std::vector<std::string> &args) {
+  TagParser &parser = TagParser::get();
+  parser.parse(args);
+  // process args
+  std::optional<GitRepository> repo = GitRepository::find();
+  if (!repo) {
+    throw std::runtime_error("Not a git repository");
+  }
+  // resolve ref to find the commit hash
+  std::string commit = parser.isCommitSet() ? parser.getCommit()
+                                            : GitObject::find(*repo, "HEAD");
+  std::string tag = parser.getTag();
+  // ERROR: if the commit doesn't exist.
+  if (!fs::exists(repo->repo_path(get_commit_path(commit)))) {
+    std::string error_message = commit + ": not a valid commit";
+    throw std::runtime_error(error_message);
+  }
+  // ERROR: if the tag already exists
+  fs::path tag_path = repo->repo_path("refs/tags/" + tag);
+  if (fs::is_regular_file(tag_path)) {
+    std::string error_message = "tag '" + tag + "' already exists";
+    throw std::runtime_error(error_message);
+  }
+
+  // create a new file in refs/tags/{name}, and write the sha of the commit.
+  create_file(tag_path, commit + "\n");
+}
+} // namespace commands

src/object.cpp

@@ -18,9 +18,7 @@ GitObject::GitObject(const std::string &format) { this->format = format; }
 void GitObject::init() {}
 
 GitObject *GitObject::read(GitRepository &repo, const std::string &sha) {
-  std::string dir = sha.substr(0, 2);
-  std::string path = sha.substr(2);
-  fs::path file_path = fs::path("objects") / dir / path;
+  fs::path file_path = get_commit_path(sha);
   fs::path paths = repo.file(file_path);
 
   if (!fs::is_regular_file(paths)) {

src/parsers/TagParser.cpp

@@ -0,0 +1,28 @@
+#include "parsers/TagParser.h"
+#include <string>
+#include <vector>
+
+void TagParser::parse(std::vector<std::string> &args) {
+  cmd.reset();
+  cmd.parse(args);
+}
+
+std::string TagParser::getTag() { return tagArg.getValue(); }
+bool TagParser::isCommitSet() const { return commitArg.isSet(); }
+std::string TagParser::getCommit() { return commitArg.getValue(); }
+
+TagParser &TagParser::get() {
+  static TagParser instance;
+  return instance;
+}
+
+TagParser::TagParser()
+    : cmd("tag", ' ', "0.1"),
+      tagArg("tagname", "Tag name", true, "HEAD", "tag name"),
+      commitArg("commit",
+                "Commit to tag to. If not specified, defaults to HEAD", false,
+                "HEAD", "commit to tag") {
+  cmd.ignoreUnmatched(true);
+  cmd.add(tagArg);
+  cmd.add(commitArg);
+}

src/repository.cpp

@@ -6,7 +6,7 @@
 
 namespace fs = std::filesystem;
 
-GitRepository::GitRepository(std::string path, bool force)
+GitRepository::GitRepository(const std::string &path, bool force)
     : worktree(fs::path(path)), gitdir(fs::path(path) / ".git") {
   if (!force && !fs::is_directory(gitdir)) {
     std::cerr << "Not a git repository: " << gitdir << "\n";
@@ -111,4 +111,4 @@ std::optional<GitRepository> GitRepository::find(const fs::path &path,
 // TODO: update this to support refs
 void GitRepository::update_head(const std::string &new_head) {
   create_file(gitdir / "HEAD", new_head + "\n");
-}
+}

src/util.cpp

@@ -169,3 +169,9 @@ std::string resolve_ref(const fs::path &ref_path, GitRepository &repo) {
   }
   return ref;
 }
+
+fs::path get_commit_path(const std::string &sha) {
+  std::string dir = sha.substr(0, 2);
+  std::string path = sha.substr(2);
+  return fs::path("objects") / dir / path;
+}