plpgsql/step2_eval.sql

   1 \i init.sql
   2 \i io.sql
   3 \i types.sql
   4 \i reader.sql
   5 \i printer.sql
   6
   7 -- ---------------------------------------------------------
   8 -- step1_read_print.sql
   9
  10 -- read
  11 CREATE FUNCTION READ(line varchar)
  12 RETURNS integer AS $$
  13 BEGIN
  14     RETURN read_str(line);
  15 END; $$ LANGUAGE plpgsql;
  16
  17 -- eval
  18 CREATE FUNCTION eval_ast(ast integer, env hstore)
  19 RETURNS integer AS $$
  20 DECLARE
  21     type           integer;
  22     symkey         varchar;
  23     seq            integer[];
  24     eseq           integer[];
  25     hash           hstore;
  26     ehash          hstore;
  27     kv             RECORD;
  28     e              integer;
  29     result         integer;
  30 BEGIN
  31     SELECT type_id INTO type FROM value WHERE value_id = ast;
  32     CASE
  33     WHEN type = 7 THEN
  34     BEGIN
  35         symkey := _valueToString(ast);
  36         IF env ? symkey THEN
  37             result := env -> symkey;
  38         ELSE
  39             RAISE EXCEPTION '''%'' not found', symkey;
  40         END IF;
  41     END;
  42     WHEN type IN (8, 9) THEN
  43     BEGIN
  44         SELECT val_seq INTO seq FROM value WHERE value_id = ast;
  45         -- Evaluate each entry creating a new sequence
  46         FOR i IN 1 .. COALESCE(array_length(seq, 1), 0) LOOP
  47             eseq[i] := EVAL(seq[i], env);
  48         END LOOP;
  49         INSERT INTO value (type_id, val_seq) VALUES (type, eseq)
  50             RETURNING value_id INTO result;
  51     END;
  52     WHEN type = 10 THEN
  53     BEGIN
  54         SELECT val_hash INTO hash FROM value WHERE value_id = ast;
  55         -- Evaluate each value for every key/value
  56         FOR kv IN SELECT * FROM each(hash) LOOP
  57             e := EVAL(CAST(kv.value AS integer), env);
  58             IF ehash IS NULL THEN
  59                 ehash := hstore(kv.key, CAST(e AS varchar));
  60             ELSE
  61                 ehash := ehash || hstore(kv.key, CAST(e AS varchar));
  62             END IF;
  63         END LOOP;
  64         INSERT INTO value (type_id, val_hash) VALUES (type, ehash)
  65             RETURNING value_id INTO result;
  66     END;
  67     ELSE
  68         result := ast;
  69     END CASE;
  70
  71     RETURN result;
  72 END; $$ LANGUAGE plpgsql;
  73
  74 CREATE FUNCTION EVAL(ast integer, env hstore)
  75 RETURNS integer AS $$
  76 DECLARE
  77     type    integer;
  78     el      integer;
  79     fname   varchar;
  80     args    integer[];
  81     result  integer;
  82 BEGIN
  83     SELECT type_id INTO type FROM value WHERE value_id = ast;
  84     IF type <> 8 THEN
  85         RETURN eval_ast(ast, env);
  86     END IF;
  87
  88     el := eval_ast(ast, env);
  89     SELECT val_string INTO fname FROM value WHERE value_id = _first(el);
  90     args := _restArray(el);
  91     EXECUTE format('SELECT %s($1);', fname) INTO result USING args;
  92     RETURN result;
  93 END; $$ LANGUAGE plpgsql;
  94
  95 -- print
  96 CREATE FUNCTION PRINT(exp integer)
  97 RETURNS varchar AS $$
  98 BEGIN
  99     RETURN pr_str(exp);
 100 END; $$ LANGUAGE plpgsql;
 101
 102
 103 -- repl
 104
 105 CREATE FUNCTION mal_intop(op varchar, args integer[])
 106 RETURNS integer AS $$
 107 DECLARE a integer; b integer; result integer;
 108 BEGIN
 109     SELECT val_int INTO a FROM value WHERE value_id = args[1];
 110     SELECT val_int INTO b FROM value WHERE value_id = args[2];
 111     EXECUTE format('INSERT INTO value (type_id, val_int) VALUES (3, $1 %s $2)
 112                     RETURNING value_id;', op) INTO result USING a, b;
 113     RETURN result;
 114 END; $$ LANGUAGE plpgsql;
 115
 116 CREATE FUNCTION mal_add(args integer[]) RETURNS integer AS $$
 117 BEGIN RETURN mal_intop('+', args); END; $$ LANGUAGE plpgsql;
 118 CREATE FUNCTION mal_subtract(args integer[]) RETURNS integer AS $$
 119 BEGIN RETURN mal_intop('-', args); END; $$ LANGUAGE plpgsql;
 120 CREATE FUNCTION mal_multiply(args integer[]) RETURNS integer AS $$
 121 BEGIN RETURN mal_intop('*', args); END; $$ LANGUAGE plpgsql;
 122 CREATE FUNCTION mal_divide(args integer[]) RETURNS integer AS $$
 123 BEGIN RETURN mal_intop('/', args); END; $$ LANGUAGE plpgsql;
 124
 125
 126 CREATE FUNCTION REP(env hstore, line varchar)
 127 RETURNS varchar AS $$
 128 BEGIN
 129     RETURN PRINT(EVAL(READ(line), env));
 130 END; $$ LANGUAGE plpgsql;
 131
 132 CREATE FUNCTION MAIN_LOOP(pwd varchar)
 133 RETURNS integer AS $$
 134 DECLARE
 135     repl_env  hstore;
 136     line      varchar;
 137     output    varchar;
 138 BEGIN
 139     repl_env := hstore(ARRAY[
 140         '+', _function('mal_add'),
 141         '-', _function('mal_subtract'),
 142         '*', _function('mal_multiply'),
 143         '/', _function('mal_divide')]);
 144     WHILE true LOOP
 145         BEGIN
 146             line := readline('user> ', 0);
 147             IF line IS NULL THEN RETURN 0; END IF;
 148             IF line <> '' THEN
 149                 output := REP(repl_env, line);
 150                 PERFORM writeline(output);
 151             END IF;
 152
 153             EXCEPTION WHEN OTHERS THEN
 154                 PERFORM writeline('Error: ' || SQLERRM);
 155         END;
 156     END LOOP;
 157 END; $$ LANGUAGE plpgsql;