plpgsql/step2_eval.sql

   1 -- ---------------------------------------------------------
   2 -- step2_eval.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(ast integer, env hstore) RETURNS integer AS $$
  22 DECLARE
  23     type           integer;
  24     symkey         varchar;
  25     seq            integer[];
  26     eseq           integer[];
  27     hash           hstore;
  28     ehash          hstore;
  29     kv             RECORD;
  30     e              integer;
  31     result         integer;
  32 BEGIN
  33     SELECT type_id INTO type FROM types.value WHERE value_id = ast;
  34     CASE
  35     WHEN type = 7 THEN
  36     BEGIN
  37         symkey := types._valueToString(ast);
  38         IF env ? symkey THEN
  39             result := env -> symkey;
  40         ELSE
  41             RAISE EXCEPTION '''%'' not found', symkey;
  42         END IF;
  43     END;
  44     WHEN type IN (8, 9) THEN
  45     BEGIN
  46         SELECT val_seq INTO seq FROM types.value WHERE value_id = ast;
  47         -- Evaluate each entry creating a new sequence
  48         FOR i IN 1 .. COALESCE(array_length(seq, 1), 0) LOOP
  49             eseq[i] := mal.EVAL(seq[i], env);
  50         END LOOP;
  51         INSERT INTO types.value (type_id, val_seq) VALUES (type, eseq)
  52             RETURNING value_id INTO result;
  53     END;
  54     WHEN type = 10 THEN
  55     BEGIN
  56         SELECT val_hash INTO hash FROM types.value WHERE value_id = ast;
  57         -- Evaluate each value for every key/value
  58         FOR kv IN SELECT * FROM each(hash) LOOP
  59             e := mal.EVAL(CAST(kv.value AS integer), env);
  60             IF ehash IS NULL THEN
  61                 ehash := hstore(kv.key, CAST(e AS varchar));
  62             ELSE
  63                 ehash := ehash || hstore(kv.key, CAST(e AS varchar));
  64             END IF;
  65         END LOOP;
  66         INSERT INTO types.value (type_id, val_hash) VALUES (type, ehash)
  67             RETURNING value_id INTO result;
  68     END;
  69     ELSE
  70         result := ast;
  71     END CASE;
  72
  73     RETURN result;
  74 END; $$ LANGUAGE plpgsql;
  75
  76 CREATE FUNCTION mal.EVAL(ast integer, env hstore) RETURNS integer AS $$
  77 DECLARE
  78     type     integer;
  79     el       integer;
  80     fname    varchar;
  81     args     integer[];
  82     result   integer;
  83 BEGIN
  84     SELECT type_id INTO type FROM types.value WHERE value_id = ast;
  85     IF type <> 8 THEN
  86         RETURN mal.eval_ast(ast, env);
  87     END IF;
  88     IF types._count(ast) = 0 THEN
  89         RETURN ast;
  90     END IF;
  91
  92     el := mal.eval_ast(ast, env);
  93     SELECT val_string INTO fname FROM types.value
  94         WHERE value_id = types._first(el);
  95     args := types._restArray(el);
  96     EXECUTE format('SELECT %s($1);', fname) INTO result USING args;
  97     RETURN result;
  98 END; $$ LANGUAGE plpgsql;
  99
 100 -- print
 101 CREATE FUNCTION mal.PRINT(exp integer) RETURNS varchar AS $$
 102 BEGIN
 103     RETURN printer.pr_str(exp);
 104 END; $$ LANGUAGE plpgsql;
 105
 106
 107 -- repl
 108
 109 CREATE FUNCTION mal.intop(op varchar, args integer[]) RETURNS integer AS $$
 110 DECLARE a integer; b integer; result integer;
 111 BEGIN
 112     SELECT val_int INTO a FROM types.value WHERE value_id = args[1];
 113     SELECT val_int INTO b FROM types.value WHERE value_id = args[2];
 114     EXECUTE format('INSERT INTO types.value (type_id, val_int)
 115                     VALUES (3, $1 %s $2)
 116                     RETURNING value_id;', op) INTO result USING a, b;
 117     RETURN result;
 118 END; $$ LANGUAGE plpgsql;
 119
 120 CREATE FUNCTION mal.add(args integer[]) RETURNS integer AS $$
 121 BEGIN RETURN mal.intop('+', args); END; $$ LANGUAGE plpgsql;
 122 CREATE FUNCTION mal.subtract(args integer[]) RETURNS integer AS $$
 123 BEGIN RETURN mal.intop('-', args); END; $$ LANGUAGE plpgsql;
 124 CREATE FUNCTION mal.multiply(args integer[]) RETURNS integer AS $$
 125 BEGIN RETURN mal.intop('*', args); END; $$ LANGUAGE plpgsql;
 126 CREATE FUNCTION mal.divide(args integer[]) RETURNS integer AS $$
 127 BEGIN RETURN mal.intop('/', args); END; $$ LANGUAGE plpgsql;
 128
 129
 130 CREATE FUNCTION mal.REP(env hstore, line varchar) RETURNS varchar AS $$
 131 BEGIN
 132     RETURN mal.PRINT(mal.EVAL(mal.READ(line), env));
 133 END; $$ LANGUAGE plpgsql;
 134
 135 CREATE FUNCTION mal.MAIN(pwd varchar) RETURNS integer AS $$
 136 DECLARE
 137     repl_env  hstore;
 138     line      varchar;
 139     output    varchar;
 140 BEGIN
 141     repl_env := hstore(ARRAY[
 142         '+', types._function('mal.add'),
 143         '-', types._function('mal.subtract'),
 144         '*', types._function('mal.multiply'),
 145         '/', types._function('mal.divide')]);
 146     WHILE true LOOP
 147         BEGIN
 148             line := io.readline('user> ', 0);
 149             IF line IS NULL THEN
 150                 PERFORM io.close(1);
 151                 RETURN 0;
 152             END IF;
 153             IF line NOT IN ('', E'\n') THEN
 154                 output := mal.REP(repl_env, line);
 155                 PERFORM io.writeline(output);
 156             END IF;
 157
 158             EXCEPTION WHEN OTHERS THEN
 159                 PERFORM io.writeline('Error: ' || SQLERRM);
 160         END;
 161     END LOOP;
 162 END; $$ LANGUAGE plpgsql;