build: split the 1423-line root CMakeLists into per-directory files with shared target helpers

cmake/reasampler_targets.cmake

@@ -0,0 +1,24 @@
+# The two shapes that repeat across src/: a pure static library and its CTest target.
+# Both are thin pass-throughs — LINK is forwarded to target_link_libraries verbatim, so
+# PUBLIC/PRIVATE keywords and link order stay visible at the call site rather than being
+# invented by the helper. Targets that genuinely deviate are written out longhand.
+
+# Every pure library carries src/ as a PUBLIC include dir: headers are included rooted
+# there ("core/json/json.h"), so a consumer needs only the link edge.
+function(reasampler_pure_library name)
+    cmake_parse_arguments(ARG "" "" "SOURCES;LINK" ${ARGN})
+    add_library(${name} STATIC ${ARG_SOURCES})
+    target_include_directories(${name} PUBLIC ${REASAMPLER_SRC_DIR})
+    if(ARG_LINK)
+        target_link_libraries(${name} ${ARG_LINK})
+    endif()
+endfunction()
+
+# Test naming is exceptionless: target <name>_tests is built from tests/test_<name>.cpp
+# and registered under its own target name.
+function(reasampler_test name)
+    cmake_parse_arguments(ARG "" "" "LINK" ${ARGN})
+    add_executable(${name}_tests ${REASAMPLER_TESTS_DIR}/test_${name}.cpp)
+    target_link_libraries(${name}_tests PRIVATE ${ARG_LINK})
+    add_test(NAME ${name}_tests COMMAND ${name}_tests)
+endfunction()