From 535ee62e0b76f986d67e9a49389996164322ec8a Mon Sep 17 00:00:00 2001
From: Ilya Andreev <bugdealer@icloud.com>
Date: Sat, 27 Jan 2024 23:07:24 +0300
Subject: [PATCH] Implement tmp::file::write and tmp::file::append (#2)

- Remove tmp::file::operator<<
- Add tmp::file::write and tmp::file::append
- Make tmp::file remember if it is binary
- Refine constructors and factories
---
 include/tmp/file.hpp | 75 ++++++++++++++++++++++++++++++--------------
 tests/file_test.cpp  | 23 +++++++++++---
 2 files changed, 70 insertions(+), 28 deletions(-)

diff --git a/include/tmp/file.hpp b/include/tmp/file.hpp
index 5edfc8b..07ea678 100644
--- a/include/tmp/file.hpp
+++ b/include/tmp/file.hpp
@@ -19,8 +19,8 @@ namespace tmp {
 /// <system's default location for temporary files>/prefix/. The prefix can be
 /// a path consisting of multiple segments.
 ///
-/// The tmp::file class also provides an additional operator<< which allows
-/// writing data to the temporary file using the same syntax as std::cout.
+/// The tmp::file class also provides an additional write and append methods
+/// which allow writing data to the temporary file.
 ///
 /// When the object is destroyed, it deletes the temporary file.
 ///
@@ -46,28 +46,19 @@ namespace tmp {
 /// the product identifier prefix. When the function returns, the tmp::file
 /// object goes out of scope and the temporary file is deleted.
 class file {
-    std::filesystem::path p;    ///< This file path
-
-    /// Deletes this file
-    void remove() const noexcept {
-        if (!this->p.empty()) {
-            std::error_code ec;
-            std::filesystem::remove_all(this->p, ec);
-        }
-    }
-
 public:
-    /// Creates a unique temporary file using the system's default location
+    /// Creates a unique temporary binary file using the system's default
+    /// location for temporary files. If a prefix is provided to the
+    /// constructor, the directory is created in the path <temp dir>/prefix/.
+    /// The prefix can be a path consisting of multiple segments.
+    file(std::string_view prefix = "") : file(prefix, /*binary=*/true) {}
+
+    /// Creates a unique temporary text file using the system's default location
     /// for temporary files. If a prefix is provided to the constructor, the
     /// directory is created in the path <temp dir>/prefix/. The prefix can be
     /// a path consisting of multiple segments.
-    explicit file(std::string_view prefix = "") {
-        const auto parent = std::filesystem::temp_directory_path() / prefix;
-        std::string arg = parent / "XXXXXX";
-
-        std::filesystem::create_directories(parent);
-        ::mkstemp(arg.data());
-        this->p = arg;
+    static file text(std::string_view prefix = "") {
+        return file(prefix, /*binary=*/false);
     }
 
     /// Creates a file from a moved @p other
@@ -94,9 +85,14 @@ class file {
         return std::addressof(this->p);
     }
 
-    /// Inserts @p content into this file
-    void operator<<(std::string_view content) const {
-        std::ofstream { this->path(), std::ios::binary } << content;
+    /// Writes the given @p content to this file discarding any previous content
+    void write(std::string_view content) const {
+        this->stream(/*append=*/false) << content;
+    }
+
+    /// Appends the given @p content to the end of this file
+    void append(std::string_view content) const {
+        this->stream(/*append=*/true) << content;
     }
 
     /// Deletes this file when the enclosing scope is exited
@@ -104,6 +100,39 @@ class file {
 
     file(const file&) = delete;              ///< not copy-constructible
     auto operator=(const file&) = delete;    ///< not copy-assignable
+
+private:
+    std::filesystem::path p;    ///< This file path
+    bool binary;                ///< This file write mode
+
+    /// Creates a unique temporary file using the system's default location
+    /// for temporary files. If a prefix is provided to the constructor, the
+    /// directory is created in the path <temp dir>/prefix/. The prefix can be
+    /// a path consisting of multiple segments.
+    explicit file(std::string_view prefix, bool binary) : binary(binary) {
+        const auto parent = std::filesystem::temp_directory_path() / prefix;
+        std::string arg = parent / "XXXXXX";
+
+        std::filesystem::create_directories(parent);
+        ::mkstemp(arg.data());
+        this->p = arg;
+    }
+
+    /// Returns a stream for this file
+    std::ofstream stream(bool append) const noexcept {
+        std::ios::openmode mode = append ? std::ios::app : std::ios::trunc;
+        return this->binary
+            ? std::ofstream { this->path(), mode | std::ios::binary }
+            : std::ofstream { this->path(), mode };
+    }
+
+    /// Deletes this file
+    void remove() const noexcept {
+        if (!this->p.empty()) {
+            std::error_code ec;
+            std::filesystem::remove_all(this->p, ec);
+        }
+    }
 };
 
 }    // namespace tmp
diff --git a/tests/file_test.cpp b/tests/file_test.cpp
index 0ad2306..148a36b 100644
--- a/tests/file_test.cpp
+++ b/tests/file_test.cpp
@@ -62,11 +62,24 @@ TEST(FileTest, MoveAssignment) {
     ASSERT_TRUE(fs::exists(fst));
 }
 
-TEST(FileTest, Streaming) {
+TEST(FileTest, Write) {
     const auto tmpfile = file();
-    tmpfile << "Hi";
+    tmpfile.write("Hello");
 
-    std::string s;
-    std::fstream(tmpfile.path(), std::ios::in) >> s;
-    ASSERT_EQ(s, "Hi");
+    std::ifstream stream(tmpfile.path());
+    std::string content(std::istreambuf_iterator<char>(stream), {});
+    ASSERT_EQ(content, "Hello");
+}
+
+TEST(FileTest, Append) {
+    const auto tmpfile = file();
+    tmpfile.write("Hello");
+
+    tmpfile.append(", world!");
+
+    std::cout << tmpfile.path() << std::endl;
+
+    std::ifstream stream(tmpfile.path());
+    std::string content(std::istreambuf_iterator<char>(stream), {});
+    ASSERT_EQ(content, "Hello, world!");
 }