test.sh

$ echo 'sdf>sdf>' | ./a.out
text|regex:1:1 'sdf>sdf>
'

test_mpc.c

#include "mpc.h"

mpc_parser_t* gen_parser() {
    mpc_parser_t* Entity    = mpc_new("entity");
    mpc_parser_t* Text      = mpc_new("text");
    mpc_parser_t* All       = mpc_new("all");

    mpc_err_t* err = mpca_lang(MPCA_LANG_WHITESPACE_SENSITIVE,
        "entity : /&[a-zA-Z0-9_#]+;/            ;\n"
        "text : /.+/                            ;\n"
        "all : (<entity> | <text>)*             ;\n"
        , Entity, Text, All, NULL);

    if (err != NULL) {
        mpc_err_print(err);
        mpc_err_delete(err);
        return NULL;
    }

    return All;
}

int main() {
    mpc_result_t r;
    if (mpc_parse_pipe("stdin", stdin, gen_parser(), &r)) {
        mpc_ast_print((mpc_ast_t*)r.output);
        mpc_ast_delete((mpc_ast_t*)r.output);
    } else {
        mpc_err_print(r.error);
        mpc_err_delete(r.error);
    }
}