plpgsql/step1_read_print.sql

   1 -- ---------------------------------------------------------
   2 -- step1_read_print.sql
   3
   4 \i init.sql
   5 \i io.sql
   6 \i types.sql
   7 \i reader.sql
   8 \i printer.sql
   9
  10 -- ---------------------------------------------------------
  11
  12 CREATE SCHEMA mal;
  13
  14 -- read
  15 CREATE FUNCTION mal.READ(line varchar) RETURNS integer AS $$
  16 BEGIN
  17     RETURN reader.read_str(line);
  18 END; $$ LANGUAGE plpgsql;
  19
  20 -- eval
  21 CREATE FUNCTION mal.EVAL(ast integer, env varchar) RETURNS integer AS $$
  22 BEGIN
  23     RETURN ast;
  24 END; $$ LANGUAGE plpgsql;
  25
  26 -- print
  27 CREATE FUNCTION mal.PRINT(exp integer) RETURNS varchar AS $$
  28 BEGIN
  29     RETURN printer.pr_str(exp);
  30 END; $$ LANGUAGE plpgsql;
  31
  32
  33 -- repl
  34
  35 CREATE FUNCTION mal.REP(line varchar) RETURNS varchar AS $$
  36 BEGIN
  37     RETURN mal.PRINT(mal.EVAL(mal.READ(line), ''));
  38 END; $$ LANGUAGE plpgsql;
  39
  40 CREATE FUNCTION mal.MAIN(pwd varchar) RETURNS integer AS $$
  41 DECLARE
  42     line      varchar;
  43     output    varchar;
  44 BEGIN
  45     WHILE true
  46     LOOP
  47         BEGIN
  48             line := io.readline('user> ', 0);
  49             IF line IS NULL THEN
  50                 PERFORM io.close(1);
  51                 RETURN 0;
  52             END IF;
  53             IF line NOT IN ('', E'\n') THEN
  54                 output := mal.REP(line);
  55                 PERFORM io.writeline(output);
  56             END IF;
  57
  58             EXCEPTION WHEN OTHERS THEN
  59                 PERFORM io.writeline('Error: ' || SQLERRM);
  60         END;
  61     END LOOP;
  62 END; $$ LANGUAGE plpgsql;