json_pointer: allow the feature to be disabled

Some users may not want to included it in their build/system. So allow a
cmake symbol to disable it.

A user can do 'cmake -DDISABLE_JSON_POINTER=ON <json_c_root_dir>' and
disable the json_pointer functionality. That saves about 17 KB (on an
x86_64) machine. This may be useful on smaller embedded systems; even
though the saving would be fewer kilobytes.

One thing that also needs to change a bit, is that the 'json.h' be
autogenerated via cmake, in order to conditionally include that
"json_pointer.h" file.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

.gitignore

@@ -70,6 +70,7 @@
 # It's not good practice to build directly in the source tree
 # but ignore cmake auto-generated files anyway:
 /json_config.h
+/json.h
 /config.h
 /json-c.pc
 /Makefile

CMakeLists.txt

@@ -98,6 +98,7 @@ option(ENABLE_RDRAND                  "Enable RDRAND Hardware RNG Hash Seed."
 option(ENABLE_THREADING               "Enable partial threading support."                     OFF)
 option(OVERRIDE_GET_RANDOM_SEED       "Override json_c_get_random_seed() with custom code."   OFF)
 option(DISABLE_EXTRA_LIBS             "Avoid linking against extra libraries, such as libbsd." OFF)
+option(DISABLE_JSON_POINTER           "Disable JSON pointer (RFC6901) support."               OFF)
 
 
 if (UNIX OR MINGW OR CYGWIN)
@@ -370,14 +371,13 @@ set(JSON_C_PUBLIC_HEADERS
     # Note: config.h is _not_ included here
     ${PROJECT_BINARY_DIR}/json_config.h
 
-    ${PROJECT_SOURCE_DIR}/json.h
+    ${PROJECT_BINARY_DIR}/json.h
     ${PROJECT_SOURCE_DIR}/arraylist.h
     ${PROJECT_SOURCE_DIR}/debug.h
     ${PROJECT_SOURCE_DIR}/json_c_version.h
     ${PROJECT_SOURCE_DIR}/json_inttypes.h
     ${PROJECT_SOURCE_DIR}/json_object.h
     ${PROJECT_SOURCE_DIR}/json_object_iterator.h
-    ${PROJECT_SOURCE_DIR}/json_pointer.h
     ${PROJECT_SOURCE_DIR}/json_tokener.h
     ${PROJECT_SOURCE_DIR}/json_types.h
     ${PROJECT_SOURCE_DIR}/json_util.h
@@ -404,7 +404,6 @@ set(JSON_C_SOURCES
     ${PROJECT_SOURCE_DIR}/json_c_version.c
     ${PROJECT_SOURCE_DIR}/json_object.c
     ${PROJECT_SOURCE_DIR}/json_object_iterator.c
-    ${PROJECT_SOURCE_DIR}/json_pointer.c
     ${PROJECT_SOURCE_DIR}/json_tokener.c
     ${PROJECT_SOURCE_DIR}/json_util.c
     ${PROJECT_SOURCE_DIR}/json_visit.c
@@ -414,6 +413,16 @@ set(JSON_C_SOURCES
     ${PROJECT_SOURCE_DIR}/strerror_override.c
 )
 
+if (NOT DISABLE_JSON_POINTER)
+    set(JSON_C_PUBLIC_HEADERS   ${JSON_C_PUBLIC_HEADERS}  ${PROJECT_SOURCE_DIR}/json_pointer.h)
+    set(JSON_C_SOURCES          ${JSON_C_SOURCES}         ${PROJECT_SOURCE_DIR}/json_pointer.c)
+    set(JSON_H_JSON_POINTER "#include \"json_pointer.h\"")
+else()
+    set(JSON_H_JSON_POINTER "")
+endif()
+
+configure_file(json.h.cmakein ${PROJECT_BINARY_DIR}/json.h @ONLY)
+
 include_directories(${PROJECT_SOURCE_DIR})
 include_directories(${PROJECT_BINARY_DIR})
 

json.h → json.h.cmakein

@@ -26,7 +26,7 @@ extern "C" {
 #include "json_c_version.h"
 #include "json_object.h"
 #include "json_object_iterator.h"
-#include "json_pointer.h"
+@JSON_H_JSON_POINTER@
 #include "json_tokener.h"
 #include "json_util.h"
 #include "linkhash.h"

tests/CMakeLists.txt

@@ -24,7 +24,6 @@ set(ALL_TEST_NAMES
     test_double_serializer
     test_float
     test_int_add
-    test_json_pointer
     test_locale
     test_null
     test_parse
@@ -37,6 +36,10 @@ set(ALL_TEST_NAMES
     test_visit
     test_object_iterator)
 
+if (NOT DISABLE_JSON_POINTER)
+    set(ALL_TEST_NAMES ${ALL_TEST_NAMES} test_json_pointer)
+endif()
+
 foreach(TESTNAME ${ALL_TEST_NAMES})
 
 add_executable(${TESTNAME} ${TESTNAME}.c)