Add basic support and documentation for CMake build system

CMakeLists.txt

@@ -0,0 +1,40 @@
+cmake_minimum_required(VERSION 3.22)
+project(
+        readtags
+        VERSION 0.3.0
+        DESCRIPTION "a library for looking up tag entries in tag files"
+        HOMEPAGE_URL "https://github.com/universal-ctags/libreadtags"
+        LANGUAGES C
+)
+
+set(CMAKE_C_STANDARD 99)
+
+option(LIBREADTAGS_BUILD_SHARED "Build shared/static library" OFF)
+
+set(API_VERSION 1)
+set(BUILD_VERSION 1.1.2)
+
+if (LIBREADTAGS_BUILD_SHARED)
+    message(STATUS "Building shared library")
+    add_library(${PROJECT_NAME} SHARED readtags.c)
+    set_target_properties(${PROJECT_NAME} PROPERTIES
+            VERSION ${BUILD_VERSION}
+            SOVERSION ${API_VERSION}
+            PUBLIC_HEADER readtags.h
+    )
+    install(TARGETS ${PROJECT_NAME}
+            LIBRARY DESTINATION lib
+            PUBLIC_HEADER DESTINATION include
+    )
+else ()
+    message(STATUS "Building static library")
+    add_library(${PROJECT_NAME} STATIC readtags.c)
+    install(TARGETS ${PROJECT_NAME}
+            ARCHIVE DESTINATION lib
+            PUBLIC_HEADER DESTINATION include
+    )
+endif ()
+
+add_library(universal-ctags::${PROJECT_NAME} ALIAS ${PROJECT_NAME})
+
+target_include_directories(${PROJECT_NAME} PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

README.md

@@ -1,3 +1,5 @@
+# libreadtags
+
 libreadtags is a library for reading tags files generated by ctags.
 libreadtags assumes the tags file format explained in [tags(5)](https://docs.ctags.io/en/latest/man/tags.5.html)
 of Universal-ctags.
@@ -10,3 +12,41 @@ NEWS.md describes note worty changes.
 If you are looking for command line interface for tags files,
 you will like [readtags command](https://docs.ctags.io/en/latest/man/readtags.1.html)
 shipped as part of Universal-ctags. It uses libreadtags extensively.
+
+## CMake Usage
+
+### Build as a standalone project
+
+#### Configure and build only
+
+```shell
+mkdir build
+cmake -DCMAKE_BUILD_TYPE=Release -DLIBREADTAGS_BUILD_SHARED=ON -S . -B build
+cmake --build build --target readtags
+```
+
+#### Configure and install
+
+This will install the library and headers to `/usr/local`.
+
+```shell
+mkdir build
+cmake -DCMAKE_BUILD_TYPE=Release -DLIBREADTAGS_BUILD_SHARED=ON -S . -B build
+sudo cmake --build build --target install
+```
+
+### Integrate into other CMake projects
+
+```cmake
+include(FetchContent)
+
+FetchContent_Declare(
+        readtags
+        GIT_REPOSITORY https://github.com/universal-ctags/libreadtags.git
+        GIT_TAG master
+)
+
+FetchContent_MakeAvailable(readtags)
+
+target_link_libraries(your_target PRIVATE universal-ctags::readtags)
+```