If a name isn't provided, try to infer it from the git repo (#202)

* Added assert_not_defined check

* Function to get package name form git uri and tests

* Autofix format

* If name is not provided, try to infer it from the git repo

* Unset result of cpm_package_name_from_git_uri if there is no match
- Also reordered tests to ensure that the result is actually unset when needed

* Removed trailing spaces in README

* Updated the main example with the new minimal syntax

* Well... autofix format again

* Update error message for missing name to reflect the possible auto-infer step

* Autofix format... yet again :)

README.md

@@ -71,7 +71,6 @@ add_executable(tests tests.cpp)
 include(cmake/CPM.cmake)
 
 CPMAddPackage(
-  NAME Catch2
   GITHUB_REPOSITORY catchorg/Catch2
   VERSION 2.5.0
 )

cmake/CPM.cmake

@@ -134,6 +134,19 @@ endif()
 include(FetchContent)
 include(CMakeParseArguments)
 
+# Infer package name from git repository uri (path or url)
+function(cpm_package_name_from_git_uri URI RESULT)
+  string(REGEX MATCH "([^/:]+)/?.git/?$" cpmGitUriMatch "${URI}")
+  if(DEFINED cpmGitUriMatch)
+    set(${RESULT}
+        ${CMAKE_MATCH_1}
+        PARENT_SCOPE
+    )
+  else()
+    unset(${RESULT} PARENT_SCOPE)
+  endif()
+endfunction()
+
 # Initialize logging prefix
 if(NOT CPM_INDENT)
   set(CPM_INDENT
@@ -264,12 +277,6 @@ function(CPMAddPackage)
 
   cmake_parse_arguments(CPM_ARGS "" "${oneValueArgs}" "${multiValueArgs}" "${ARGN}")
 
-  # Check for required arguments
-
-  if(NOT DEFINED CPM_ARGS_NAME)
-    message(FATAL_ERROR "CPM: 'NAME' was not provided for package added with arguments: '${ARGN}'")
-  endif()
-
   # Set default values for arguments
 
   if(NOT DEFINED CPM_ARGS_VERSION)
@@ -297,6 +304,11 @@ function(CPMAddPackage)
     if(NOT DEFINED CPM_ARGS_GIT_TAG)
       set(CPM_ARGS_GIT_TAG v${CPM_ARGS_VERSION})
     endif()
+
+    # If a name wasn't provided, try to infer it from the git repo
+    if(NOT DEFINED CPM_ARGS_NAME)
+      cpm_package_name_from_git_uri(${CPM_ARGS_GIT_REPOSITORY} CPM_ARGS_NAME)
+    endif()
   endif()
 
   set(CPM_SKIP_FETCH FALSE)
@@ -309,6 +321,15 @@ function(CPMAddPackage)
     endif()
   endif()
 
+  # Check for required arguments
+
+  if(NOT DEFINED CPM_ARGS_NAME)
+    message(
+      FATAL_ERROR
+        "CPM: 'NAME' was not provided and couldn't be automatically inferred for package added with arguments: '${ARGN}'"
+    )
+  endif()
+
   # Check if package has been added before
   cpm_check_if_package_already_added(${CPM_ARGS_NAME} "${CPM_ARGS_VERSION}" "${CPM_ARGS_OPTIONS}")
   if(CPM_PACKAGE_ALREADY_ADDED)

cmake/testing.cmake

@@ -36,6 +36,14 @@ function(ASSERT_DEFINED KEY)
   endif()
 endfunction()
 
+function(ASSERT_NOT_DEFINED KEY)
+  if(DEFINED ${KEY})
+    message(FATAL_ERROR "assertion failed: '${KEY}' is defiend")
+  else()
+    message(STATUS "test passed: '${KEY}' is not defined")
+  endif()
+endfunction()
+
 function(ASSERT_TRUTHY KEY)
   if(${${KEY}})
     message(STATUS "test passed: '${KEY}' is set truthy")

test/unit/package_name_from_git_uri.cmake

@@ -0,0 +1,28 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+include(${CPM_PATH}/CPM.cmake)
+include(${CPM_PATH}/testing.cmake)
+
+cpm_package_name_from_git_uri("https://github.com/cpm-cmake/CPM.cmake.git" name)
+assert_equal("CPM.cmake" ${name})
+
+cpm_package_name_from_git_uri("ssh://user@host.xz:123/path/to/pkg.git/" name)
+assert_equal("pkg" ${name})
+
+cpm_package_name_from_git_uri("git://host.xz/path/to/pkg.git" name)
+assert_equal("pkg" ${name})
+
+cpm_package_name_from_git_uri("git@host.xz:cool-pkg.git" name)
+assert_equal("cool-pkg" ${name})
+
+cpm_package_name_from_git_uri("file:///path/to/pkg33.git" name)
+assert_equal("pkg33" ${name})
+
+cpm_package_name_from_git_uri("../local-repo/.git" name)
+assert_equal("local-repo" ${name})
+
+cpm_package_name_from_git_uri("asdf" name)
+assert_not_defined(name)
+
+cpm_package_name_from_git_uri("/something.git/stuff" name)
+assert_not_defined(name)