[Relay][Parser] simplify build script, remove python 2 support (apach…

…e#3419)

* simplify build script, remove python 2 support

* remove py2 file

* update py3

cmake/modules/ANTLR.cmake

@@ -16,44 +16,19 @@
 # under the License.
 
 if(USE_ANTLR)
-  file(GLOB_RECURSE ANTLR4
-        /usr/local/lib/antlr-*-complete.jar
-        /usr/local/Cellar/*antlr-*-complete.jar)
+  set(RELAY_PARSER_DIR
+    ${CMAKE_CURRENT_SOURCE_DIR}/python/tvm/relay/grammar)
 
-if(ANTLR4)
-    # Get the first element of the list of antlr jars.
-    # Sort and reverse the list so the item selected is the highest
-    #   version in lib or else in Cellar if no lib installation exists.
-    list(SORT ANTLR4)
-    list(REVERSE ANTLR4)
-    list(GET ANTLR4 0 ANTLR4)
-    set(RELAY_PARSER_DIR
-      ${CMAKE_CURRENT_SOURCE_DIR}/python/tvm/relay/grammar)
+  set(RELAY_PARSER
+    ${RELAY_PARSER_DIR}/py3/RelayVisitor.py
+    ${RELAY_PARSER_DIR}/py3/RelayParser.py
+    ${RELAY_PARSER_DIR}/py3/RelayLexer.py)
 
-    set(RELAY_PARSER
-      ${RELAY_PARSER_DIR}/py2/RelayVisitor.py
-      ${RELAY_PARSER_DIR}/py2/RelayParser.py
-      ${RELAY_PARSER_DIR}/py2/RelayLexer.py
+  # Generate ANTLR grammar for parsing.
+  add_custom_command(OUTPUT ${RELAY_PARSER}
+    COMMAND antlr4 -visitor -no-listener -Dlanguage=Python3 ${RELAY_PARSER_DIR}/Relay.g4 -o ${RELAY_PARSER_DIR}/py3
+    DEPENDS ${RELAY_PARSER_DIR}/Relay.g4
+    WORKING_DIRECTORY ${RELAY_PARSER_DIR})
 
-      ${RELAY_PARSER_DIR}/py3/RelayVisitor.py
-      ${RELAY_PARSER_DIR}/py3/RelayParser.py
-      ${RELAY_PARSER_DIR}/py3/RelayLexer.py)
-
-    set(JAVA_HOME $ENV{JAVA_HOME})
-    if (NOT DEFINED JAVA_HOME)
-      # Hack to get system to search for Java itself.
-      set(JAVA_HOME "/usr")
-    endif()
-
-    # Generate ANTLR grammar for parsing.
-    add_custom_command(OUTPUT ${RELAY_PARSER}
-      COMMAND ${JAVA_HOME}/bin/java -jar ${ANTLR4} -visitor -no-listener -Dlanguage=Python2 ${RELAY_PARSER_DIR}/Relay.g4 -o ${RELAY_PARSER_DIR}/py2
-      COMMAND ${JAVA_HOME}/bin/java -jar ${ANTLR4} -visitor -no-listener -Dlanguage=Python3 ${RELAY_PARSER_DIR}/Relay.g4 -o ${RELAY_PARSER_DIR}/py3
-      DEPENDS ${RELAY_PARSER_DIR}/Relay.g4
-      WORKING_DIRECTORY ${RELAY_PARSER_DIR})
-
-    add_custom_target(relay_parser ALL DEPENDS ${RELAY_PARSER})
-  else()
-    message(FATAL_ERROR "Can't find ANTLR4: ANTLR4=" ${ANTLR4})
-  endif()
+  add_custom_target(relay_parser ALL DEPENDS ${RELAY_PARSER})
 endif(USE_ANTLR)

python/tvm/relay/_parser.py

@@ -43,14 +43,9 @@ def __init__(self, message):
 
 PYTHON_VERSION = sys.version_info.major
 try:
-    if PYTHON_VERSION == 2:
-        from .grammar.py2.RelayVisitor import RelayVisitor
-        from .grammar.py2.RelayParser import RelayParser
-        from .grammar.py2.RelayLexer import RelayLexer
-    else:
-        from .grammar.py3.RelayVisitor import RelayVisitor
-        from .grammar.py3.RelayParser import RelayParser
-        from .grammar.py3.RelayLexer import RelayLexer
+    from .grammar.py3.RelayVisitor import RelayVisitor
+    from .grammar.py3.RelayParser import RelayParser
+    from .grammar.py3.RelayLexer import RelayLexer
 except ImportError:
     raise ParseError("Couldn't find ANTLR parser. Try building with USE_ANTLR=ON.")