Add formula

Formula/clang-format@10.rb

@@ -0,0 +1,64 @@
+class ClangFormatAT10 < Formula
+  desc "Formatting tools for C, C++, Obj-C, Java, JavaScript, TypeScript"
+  homepage "https://clang.llvm.org/docs/ClangFormat.html"
+  # The LLVM Project is under the Apache License v2.0 with LLVM Exceptions
+  license "Apache-2.0"
+  version_scheme 1
+  head "https://github.com/llvm/llvm-project.git"
+
+  stable do
+    url "https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.1/llvm-10.0.1.src.tar.xz"
+    sha256 "c5d8e30b57cbded7128d78e5e8dad811bff97a8d471896812f57fa99ee82cdf3"
+
+    resource "clang" do
+      url "https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.1/clang-10.0.1.src.tar.xz"
+      sha256 "f99afc382b88e622c689b6d96cadfa6241ef55dca90e87fc170352e12ddb2b24"
+    end
+
+    resource "libcxx" do
+      url "https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.1/libcxx-10.0.1.src.tar.xz"
+      sha256 "def674535f22f83131353b3c382ccebfef4ba6a35c488bdb76f10b68b25be86c"
+    end
+  end
+
+  depends_on "cmake" => :build
+  depends_on "ninja" => :build
+
+  uses_from_macos "libxml2"
+  uses_from_macos "ncurses"
+  uses_from_macos "zlib"
+
+  def install
+    if build.head?
+      ln_s buildpath/"libcxx", buildpath/"llvm/projects/libcxx"
+      ln_s buildpath/"clang", buildpath/"llvm/tools/clang"
+    else
+      (buildpath/"projects/libcxx").install resource("libcxx")
+      (buildpath/"tools/clang").install resource("clang")
+    end
+
+    llvmpath = build.head? ? buildpath/"llvm" : buildpath
+
+    mkdir llvmpath/"build" do
+      args = std_cmake_args
+      args << "-DLLVM_ENABLE_LIBCXX=ON"
+      args << ".."
+      system "cmake", "-G", "Ninja", *args
+      system "ninja", "clang-format"
+    end
+
+    bin.install llvmpath/"build/bin/clang-format"
+    bin.install llvmpath/"tools/clang/tools/clang-format/git-clang-format"
+    (share/"clang").install Dir[llvmpath/"tools/clang/tools/clang-format/clang-format*"]
+  end
+
+  test do
+    # NB: below C code is messily formatted on purpose.
+    (testpath/"test.c").write <<~EOS
+      int         main(char *args) { \n   \t printf("hello"); }
+    EOS
+
+    assert_equal "int main(char *args) { printf(\"hello\"); }\n",
+        shell_output("#{bin}/clang-format -style=Google test.c")
+  end
+end