auto generate sql parser files (#473)

### What problem were solved in this pull request?

Issue Number: close #305

Problem:
当语法文件flex_sql.l和yacc_sql.y变更时，必须手动执行 gen_parser.sh 生成C++代码文件，比较麻烦。

### What is changed and how it works?
cmake中增加 add_custom_command，在 flex_sql.l 和
yacc_sql.y文件变更时自动重新生成相关的C++代码文件。
当然在这些文件不存在时，也会执行gen_parser.sh生成代码。

### Other information
将生成的代码文件加入了.gitignore，后续不需要再提交这些文件

.github/workflows/build.yml

@@ -61,12 +61,18 @@ jobs:
     runs-on: macos-latest
 
     steps:
+    - name: Init environment
+      shell: bash
+      run: |
+        brew install bison
+
     - name: Checkout repository and submodules
       uses: actions/checkout@v2
 
     - name: Build
       shell: bash
       run: |
         export ASAN_OPTIONS=detect_container_overflow=0
+        export PATH="/opt/homebrew/opt/bison/bin:$PATH"
         sudo bash build.sh init
         bash build.sh release --make -j4

.gitignore

@@ -27,3 +27,9 @@ GPATH
 GTAGS
 docs/book
 #*#
+
+# ignore generated files
+src/observer/sql/parser/lex_sql.cpp
+src/observer/sql/parser/lex_sql.h
+src/observer/sql/parser/yacc_sql.cpp
+src/observer/sql/parser/yacc_sql.hpp

src/observer/CMakeLists.txt

@@ -2,9 +2,21 @@ MESSAGE(STATUS "This is CMAKE_CURRENT_SOURCE_DIR dir " ${CMAKE_CURRENT_SOURCE_DI
 
 INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR})
 
+SET (PARSER_WORKDIR ${CMAKE_CURRENT_SOURCE_DIR}/sql/parser)
+SET (PARSER_SOURCES ${PARSER_WORKDIR}/lex_sql.cpp ${PARSER_WORKDIR}/yacc_sql.cpp)
+SET (PARSER_HEADERS ${PARSER_WORKDIR}/lex_sql.h ${PARSER_WORKDIR}/yacc_sql.hpp)
+ADD_CUSTOM_COMMAND(
+    OUTPUT ${PARSER_SOURCES} ${PARSER_HEADERS}
+    COMMAND bash gen_parser.sh
+    DEPENDS ${PARSER_WORKDIR}/lex_sql.l ${PARSER_WORKDIR}/yacc_sql.y
+    WORKING_DIRECTORY ${PARSER_WORKDIR}
+    COMMENT "generating lex and yacc files"
+)
+
 FILE(GLOB_RECURSE ALL_SRC *.cpp *.c)
 SET(MAIN_SRC ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp)
 MESSAGE("MAIN SRC: " ${MAIN_SRC})
+SET(LIB_SRC ${LIB_SRC} ${PARSER_SOURCES})
 FOREACH (F ${ALL_SRC})
 
     IF (NOT ${F} STREQUAL ${MAIN_SRC})