Thomas Capricelli

How to use flex and bison with qmake (my own way)

qmake (sort of) supports lex/yacc, but modern people prefer to use flex/bison. If you google, you can find some tricks like convincing qmake that yacc is spelled ‘bison’ and so on.  Morever qmake supports for lex/yacc has several drawbacks, such as weird naming scheme, and (when using the tricks), dependencies are not building files in the right order.

Finally, I created my own *.pri files, and here they are:

% cat flex.pri
[plain]
flex.name = Flex ${QMAKE_FILE_IN}
flex.input = FLEXSOURCES
flex.output = ${QMAKE_FILE_PATH}/${QMAKE_FILE_BASE}.lexer.cpp
flex.commands = flex -o ${QMAKE_FILE_PATH}/${QMAKE_FILE_BASE}.lexer.cpp ${QMAKE_FILE_IN}
flex.CONFIG += target_predeps
flex.variable_out = GENERATED_SOURCES
silent:flex.commands = @echo Lex ${QMAKE_FILE_IN} && $$flex.commands
QMAKE_EXTRA_COMPILERS += flex
[/plain]
% cat bison.pri
[plain]
bison.name = Bison ${QMAKE_FILE_IN}
bison.input = BISONSOURCES
bison.output = ${QMAKE_FILE_PATH}/${QMAKE_FILE_BASE}.parser.cpp
bison.commands = bison -d -o ${QMAKE_FILE_PATH}/${QMAKE_FILE_BASE}.parser.cpp ${QMAKE_FILE_IN}
bison.CONFIG += target_predeps
bison.variable_out = GENERATED_SOURCES
silent:bison.commands = @echo Bison ${QMAKE_FILE_IN} && $$bison.commands
QMAKE_EXTRA_COMPILERS += bison
bison_header.input = BISONSOURCES
bison_header.output = ${QMAKE_FILE_PATH}/${QMAKE_FILE_BASE}.parser.hpp
bison_header.commands = bison -d -o ${QMAKE_FILE_PATH}/${QMAKE_FILE_BASE}.parser.cpp ${QMAKE_FILE_IN}
bison_header.CONFIG += target_predeps no_link
silent:bison_header.commands = @echo Bison ${QMAKE_FILE_IN} && $$bison.commands
QMAKE_EXTRA_COMPILERS += bison_header
[/plain]

Of course, the proper way to use those is to include them and then define FLEXSOURCES / BISONSOURCES as needed. Example:
[plain]
include(flex.pri)
include(bison.pri)
FLEXSOURCES = myproject.l
BISONSOURCES = myproject.y
[/plain]