Generate jerryscript-config.h before build (#2934)

Previously after the library was build there was no easy way
to get back the information of how it was build.

This change adds a bit of CMake code to generate the
jerryscript-config.h file containing the default options
and adding the modified build options/features.

JerryScript-DCO-1.0-Signed-off-by: Peter Gal pgal.u-szeged@partner.samsung.com

jerry-core/CMakeLists.txt

@@ -169,7 +169,7 @@ if(ENABLE_ALL_IN_ONE_SOURCE)
   set(ALL_IN_FILE_H "${CMAKE_BINARY_DIR}/src/jerryscript.h")
   set(JERRYSCRIPT_CONFIG_H "${CMAKE_BINARY_DIR}/src/jerryscript-config.h")
 
-  add_custom_command(OUTPUT ${ALL_IN_FILE} ${ALL_IN_FILE_H} ${JERRYSCRIPT_CONFIG_H}
+  add_custom_command(OUTPUT ${ALL_IN_FILE} ${ALL_IN_FILE_H}
                      COMMAND python ${CMAKE_SOURCE_DIR}/tools/srcgenerator.py
                              --jerry-core
                              --output-dir ${CMAKE_BINARY_DIR}/src
@@ -178,6 +178,14 @@ if(ENABLE_ALL_IN_ONE_SOURCE)
                              ${CMAKE_SOURCE_DIR}/tools/srcgenerator.py
                              ${CMAKE_SOURCE_DIR}/tools/srcmerger.py
   )
+
+  # The "true" jerryscript-config.h will be generated by the configure_file below,
+  # which contains the default options and the ones passed for the CMake.
+  # The input for this is the jerryscript-config.h generated by the command above.
+  set(JERRYSCRIPT_GEN_CONFIG_H ${CMAKE_CURRENT_BINARY_DIR}/jerryscript-config.h)
+  add_custom_command(OUTPUT ${JERRYSCRIPT_CONFIG_H}
+                     COMMAND ${CMAKE_COMMAND} -E copy ${JERRYSCRIPT_GEN_CONFIG_H} ${JERRYSCRIPT_CONFIG_H}
+                     DEPENDS ${ALL_IN_FILE_C} ${ALL_IN_FILE_H})
   add_custom_target(generate-single-source-jerry DEPENDS ${ALL_IN_FILE} ${ALL_IN_FILE_H})
   add_dependencies(generate-single-source generate-single-source-jerry)
 
@@ -245,6 +253,16 @@ if(EXISTS ${JERRY_PROFILE})
   file(READ "${JERRY_PROFILE}" PROFILE_SETTINGS)
   string(REGEX REPLACE "^#.*$" "" PROFILE_SETTINGS "${PROFILE_SETTINGS}")
   string(REGEX REPLACE "[\r|\n]" ";" PROFILE_SETTINGS "${PROFILE_SETTINGS}")
+
+  # Process entries and save them as CMake variables.
+  # This is required to correctly generate the jerryscript-config.h file.
+  foreach(PROFILE_ENTRY ${PROFILE_SETTINGS})
+    string(REPLACE "=" ";" PROFILE_ENTRY "${PROFILE_ENTRY}")
+    list(GET PROFILE_ENTRY 0 PROFILE_KEY)
+    list(GET PROFILE_ENTRY 1 PROFILE_VALUE)
+    set(${PROFILE_KEY} ${PROFILE_VALUE})
+  endforeach()
+
   set(DEFINES_JERRY ${DEFINES_JERRY} ${PROFILE_SETTINGS})
 else()
   message(FATAL_ERROR "Profile file: '${JERRY_PROFILE}' doesn't exist!")
@@ -280,6 +298,88 @@ set(DEFINES_JERRY ${DEFINES_JERRY} JERRY_GLOBAL_HEAP_SIZE=${JERRY_GLOBAL_HEAP_SI
 # Maximum size of stack memory usage
 set(DEFINES_JERRY ${DEFINES_JERRY} JERRY_STACK_LIMIT=${JERRY_STACK_LIMIT})
 
+## This function is to read "config.h" for default values
+function(read_set_defines FILE PREFIX OUTPUTVAR)
+  file(READ "${CMAKE_CURRENT_SOURCE_DIR}/${FILE}" INPUT_FILE_CONTENTS)
+
+  # match all "#define <PREFIX>\n" lines
+  # notes:
+  #  * before the "#" there must be a newline and any number of spaces.
+  #  * after the "#" there can be any number of spaces.
+  string(REGEX MATCHALL "\r?\n[ ]*#[ ]*define ${PREFIX}[^\n]*"
+         RAW_DEFINES "${INPUT_FILE_CONTENTS}")
+
+  set(SELECTED_VARS )
+
+  # Transform the defines to a list of (<name>; <value>; <name 2>; <value 2>; ...) list
+  foreach(DEFINE_ENTRY ${RAW_DEFINES})
+    # by default every define value is empty
+    set(DEFINE_VALUE " ")
+
+    # split up the define at the space between the define name and value (if there is any)
+
+    # first remove "#define" part of the string
+    string(REGEX REPLACE "\r?\n[ ]*#[ ]*define[ ]+" "" DEFINE_KEY_VALUE "${DEFINE_ENTRY}")
+    string(FIND "${DEFINE_KEY_VALUE}" " " DEFINE_KEY_IDX)
+    string(LENGTH "${DEFINE_KEY_VALUE}" DEFINE_LENGTH)
+
+    if (DEFINE_KEY_IDX EQUAL "-1")
+        set(DEFINE_KEY ${DEFINE_KEY_VALUE})
+    else()
+        string(SUBSTRING "${DEFINE_KEY_VALUE}" 0 ${DEFINE_KEY_IDX} DEFINE_KEY)
+        string(SUBSTRING "${DEFINE_KEY_VALUE}" ${DEFINE_KEY_IDX} -1 DEFINE_VALUE)
+        string(STRIP "${DEFINE_VALUE}" DEFINE_VALUE)
+    endif()
+
+    list(APPEND SELECTED_VARS ${DEFINE_KEY} ${DEFINE_VALUE})
+  endforeach()
+
+  set(${OUTPUTVAR} ${SELECTED_VARS} PARENT_SCOPE)
+endfunction(read_set_defines)
+
+# CONFIG_DEFAULTS contains define name and values which have the JERRY_ prefix
+# as a list of (<name>; <value>; <name 2>; <value 2>; ...)
+read_set_defines("config.h" JERRY_ CONFIG_DEFAULTS)
+
+
+## Process the default values and build options to generate build config defines
+list(LENGTH CONFIG_DEFAULTS CONFIG_DEFAULT_LENGTH)
+math(EXPR CONFIG_DEFAULT_LENGTH "${CONFIG_DEFAULT_LENGTH} - 1")
+
+set(JERRY_MODIFIED_OPTIONS)
+foreach(CONFIG_IDX RANGE 0 ${CONFIG_DEFAULT_LENGTH} 2)
+  list(GET CONFIG_DEFAULTS ${CONFIG_IDX} KEY)
+  math(EXPR VALUE_IDX "${CONFIG_IDX} + 1")
+  list(GET CONFIG_DEFAULTS ${VALUE_IDX} VALUE)
+
+  # ${KEY} is the value for the given variable (aka define)
+  # normalize ON/OFF cmake values to 1/0 for easier processing.
+  if(${KEY} STREQUAL "ON")
+    set(${KEY} 1)
+  elseif(${KEY} STREQUAL "OFF")
+    set(${KEY} 0)
+  endif()
+
+  # Generate "#define JERRY_<CONFIG> <CONFIG_VALUE>" entries if it is different from
+  # the config default.
+
+  # If the define loaded from the config file have a different value than the
+  # relevant option passed for the CMake means that it does not have a default value.
+  if(DEFINED ${KEY} AND NOT (${KEY} STREQUAL ${VALUE}))
+    set(JERRY_MODIFIED_OPTIONS "${JERRY_MODIFIED_OPTIONS}#define ${KEY} ${${KEY}}\n")
+  endif()
+endforeach()
+
+# Generate the jerryscript-config.h file into the build directory
+# This file will contain the options different from the default (aka it's the build config).
+if(JERRY_MODIFIED_OPTIONS)
+  set(JERRY_BUILD_CFG
+      "Generated differences from default by CMake based on build options:\n${JERRY_MODIFIED_OPTIONS}")
+else()
+  set(JERRY_BUILD_CFG "JerryScript configuration")
+endif()
+configure_file(config.h jerryscript-config.h @ONLY)
+
 add_library(${JERRY_CORE_NAME} ${SOURCE_CORE_FILES})
 
 target_compile_definitions(${JERRY_CORE_NAME} PUBLIC ${DEFINES_JERRY})
@@ -304,4 +404,5 @@ configure_file(libjerry-core.pc.in libjerry-core.pc @ONLY)
 
 install(TARGETS ${JERRY_CORE_NAME} DESTINATION lib)
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libjerry-core.pc DESTINATION lib/pkgconfig)
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/jerryscript-config.h DESTINATION include)
 install(DIRECTORY ${INCLUDE_CORE_PUBLIC}/ DESTINATION include)

jerry-core/config.h

@@ -13,8 +13,10 @@
  * limitations under the License.
  */
 
-#ifndef CONFIG_H
-#define CONFIG_H
+#ifndef JERRYSCRIPT_CONFIG_H
+#define JERRYSCRIPT_CONFIG_H
+
+// @JERRY_BUILD_CFG@
 
 /**
  * Built-in configurations
@@ -698,4 +700,4 @@
 #  error "Date does not support float32"
 #endif
 
-#endif /* !CONFIG_H */
+#endif /* !JERRYSCRIPT_CONFIG_H */