From 47ed1270865c65f1ac97b37b084cdfa771550beb Mon Sep 17 00:00:00 2001
From: Teon Banek <teon.banek@memgraph.io>
Date: Wed, 8 Mar 2017 08:59:37 +0100
Subject: [PATCH] Generate openCypher parser sources if missing

Summary:
Makes cmake aware that parser source files are generated, so that it can
know how to set the dependencies for the underlying build tool. When the
files do not exist, invoking e.g. `make` will also run antlr to generate
them. Files will be regenerated only if their dependency changed
(Cypher.g4 file in this case).

Reviewers: buda, florijan

Reviewed By: buda

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D94
---
 CMakeLists.txt | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 14cbb72bb..5c0b90d73 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,9 +9,14 @@ if(NOT UNIX)
     message(FATAL "Unsupported operating system.")
 endif()
 
+# Set `make clean` to ignore outputs of add_custom_command. If generated files
+# need to be cleaned, set ADDITIONAL_MAKE_CLEAN_FILES property.
+set_directory_properties(PROPERTIES CLEAN_NO_CUSTOM TRUE)
+
 # ccache setup
 # ccache isn't enabled all the time because it makes some problem
 # during the code coverage process
+find_program(CCACHE_FOUND ccache)
 option(USE_CCACHE "ccache:" ON)
 message(STATUS "CCache: ${USE_CCACHE}")
 if(CCACHE_FOUND AND USE_CCACHE)
@@ -269,21 +274,25 @@ set(opencypher_grammar ${opencypher_frontend}/grammar/Cypher.g4)
 
 # enumerate all files that are generated from antlr
 set(antlr_opencypher_generated_src
-   ${opencypher_frontend}/generated/CypherLexer.cpp 
-   ${opencypher_frontend}/generated/CypherParser.cpp
-   ${opencypher_frontend}/generated/CypherBaseVisitor.cpp
-   ${opencypher_frontend}/generated/CypherVisitor.cpp
+   ${opencypher_generated}/CypherLexer.cpp 
+   ${opencypher_generated}/CypherParser.cpp
+   ${opencypher_generated}/CypherBaseVisitor.cpp
+   ${opencypher_generated}/CypherVisitor.cpp
 )
 
+# Provide a command to generate sources if missing. If this were a
+# custom_target, it would always run and we don't want that.
+add_custom_command(OUTPUT ${antlr_opencypher_generated_src}
+  COMMAND
+  ${CMAKE_COMMAND} -E make_directory ${opencypher_generated}
+  COMMAND
+  java -jar ${CMAKE_SOURCE_DIR}/libs/antlr-4.6-complete.jar -Dlanguage=Cpp -visitor -o ${opencypher_generated} -package antlropencypher ${opencypher_grammar}
+  WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
+  DEPENDS ${opencypher_grammar})
+
 # add custom target for generation
 add_custom_target(generate_opencypher_parser
-   COMMAND
-   ${CMAKE_COMMAND} -E make_directory ${opencypher_generated}
-   COMMAND 
-   java -jar ${CMAKE_SOURCE_DIR}/libs/antlr-4.6-complete.jar -Dlanguage=Cpp -visitor -o ${opencypher_generated} -package antlropencypher ${opencypher_grammar}
-   WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
-   DEPENDS ${opencypher_grammar}
-   )
+  DEPENDS ${antlr_opencypher_generated_src})
 
 # include antlr header files
 include_directories(
@@ -344,10 +353,12 @@ set(memgraph_src_files
 
 # STATIC library used by memgraph executables
 add_library(memgraph_lib STATIC ${memgraph_src_files})
+add_dependencies(memgraph_lib generate_opencypher_parser)
 # -----------------------------------------------------------------------------
 
 # STATIC PIC library used by query engine
 add_library(memgraph_pic STATIC ${memgraph_src_files})
+add_dependencies(memgraph_pic generate_opencypher_parser)
 set_property(TARGET memgraph_pic PROPERTY POSITION_INDEPENDENT_CODE TRUE)
 # -----------------------------------------------------------------------------