#!/bin/sh
# vim: ts=4 sw=4 ft=sh expandtab
#
# Test whether a single Mercury source file compiles cleanly.
# If not, show the error messages through a pager.
#
# It can be invoked in two ways. The first is simply "mtest file.m",
# which tests whether file.m compiles cleanly. The second, which is handy
# if you anticipate having to invoke mtest on the same file many times
# in a row but don't want to keep typing its name, is to set the
# environment variable MFILE to file.m, and then just invoke "mtest".
#

case "$#" in
    0)
        if test "${MFILE}" = ""
        then
            echo "mtest: the environment variable MFILE must be set"
            echo "when invoked without arguments."
            exit 1
        fi
        ;;
    1)
        MFILE="$1"
        export MFILE
        ;;
    *)
        echo "usage: mtest [filename.m]"
        exit 1
        ;;
esac

MODULE=`m_file_module ${MFILE}`
if test $? != 0
then
    # Since the exit status indicates that m_file_module failed,
    # its output will be its error message, not the module name.
    echo "${MODULE}"
else
    # Run the mmake with -j6, unless the user specifies a different level
    # of parallelism through the environment variable MTEST_JFACTOR.
    #
    # Put the output through less, unless the user specifies a different pager
    # via the standard PAGER environment variable.
    #
    # Note that it is important we push the output of mmake, as well as
    # the .err file, through the pager. If e.g. an error in another module
    # prevents mmake from successfully generating all the .int* files
    # that ${MODULE} requires, then what will be in ${MODULE}.err will
    # NOT reflect the errors attributable to its current contents. Instead,
    # it will reflect the errors attributable to what its content was
    # *the last time mmc actually tried to compile it*, which in this case
    # would be from *before* the invocation of mtest. This shell script
    # has no simple means to distinguish between (a) errors reported by
    # mmc when compiling ${MODULE} from (b) errors reported by mmc
    # *before* it starts compiling ${MODULE}, but the output from mmake
    # should allow the user to make that distinction.
    ( mmake -k -j${MTEST_JFACTOR:-6} "${MODULE}.c_date" ; \
        cat "${MODULE}.err" ) 2>&1 | ${PAGER:-less}
fi