Refactor CMakeLists.txt

This allows ANTLR to be compiled locally instead of globally. This
prevents bugs when emscripten is/isn't used.

tools/CMakeLists.txt

@@ -0,0 +1,63 @@
+set(DIAGON_TOOLS_DIR ${CMAKE_CURRENT_SOURCE_DIR} CACHE STRING "")
+
+# ┌─────────────────────────────────────────────────┐
+# │ ANTLR                                           │
+# └─────────────────────────────────────────────────┘
+execute_process(
+  COMMAND bash download_and_patch.sh
+  WORKING_DIRECTORY ${DIAGON_TOOLS_DIR}
+)
+
+FetchContent_Declare(antlr
+  GIT_REPOSITORY https://github.com/antlr/antlr4
+  GIT_TAG 4.8)
+
+FetchContent_GetProperties(antlr)
+if(NOT json_POPULATED)
+  FetchContent_Populate(antlr)
+  SET(WITH_LIBCXX OFF CACHE BOOL "")
+  add_subdirectory(
+    ${antlr_SOURCE_DIR}/runtime/Cpp
+    ${antlr_BINARY_DIR}
+    EXCLUDE_FROM_ALL)
+  target_include_directories(antlr4_static
+    PUBLIC ${antlr_SOURCE_DIR}/runtime/Cpp/runtime/src
+  )
+endif()
+
+# Function
+#   ANTLR(<file.g4>)
+#
+# Description:
+#   Take an ANTLR file and produce a CMake rule to generate the corresponding
+#   C++ files.
+#
+# Notes:
+#   The ANTLR file path must be relative to ${CMAKE_CURRENT_SOURCE_DIR}
+#
+# Example:
+#   ANTLR(Grammar.g4)
+function(ANTLR source)
+  get_filename_component(source_filename ${CMAKE_CURRENT_SOURCE_DIR}/${source} NAME_WE)
+  get_filename_component(source_src_dir  ${CMAKE_CURRENT_SOURCE_DIR}/${source} DIRECTORY)
+  get_filename_component(source_gen_dir  ${CMAKE_CURRENT_BINARY_DIR}/${source} DIRECTORY)
+  add_custom_command(
+    OUTPUT
+      ${source_gen_dir}/${source_filename}Lexer.cpp
+      ${source_gen_dir}/${source_filename}Parser.cpp
+      ${source_gen_dir}/${source_filename}Lexer.h
+      ${source_gen_dir}/${source_filename}Parser.h
+    COMMAND
+      java
+    ARGS
+      -jar ${DIAGON_TOOLS_DIR}/antlr.jar
+      -Dlanguage=Cpp
+      -no-listener
+      -no-visitor
+      -o ${source_gen_dir}
+      ${source_src_dir}/${source_filename}.g4
+    MAIN_DEPENDENCY
+      ${source_src_dir}/${source_filename}.g4
+  )
+endfunction()
+

tools/antlr/download_and_patch.sh

@@ -1,15 +0,0 @@
-cd "$(dirname "$0")"
-top=$(pwd)
-
-if [ -d cpp_runtime ]
-then
-  exit
-fi
-
-mkdir -p cpp_runtime
-
-## Download the ANTLR executable.
-curl http://www.antlr.org/download/antlr-4.8-complete.jar -L -o antlr.jar
-
-## Download the C++ runtime.
-git clone --depth 1 https://github.com/antlr/antlr4 -b 4.8

tools/download_and_patch.sh

@@ -0,0 +1,9 @@
+cd "$(dirname "$0")"
+top=$(pwd)
+
+if [[ -f "antlr.jar" ]]
+then
+  exit
+else
+  curl http://www.antlr.org/download/antlr-4.8-complete.jar -L -o antlr.jar
+fi