Skip to content

P
Postgres FD Implementation
Commit a72dd7a9 authored by Tom Lane's avatar Tom Lane
Browse files
Options

Okay, I've had it with answering newbie questions about why plpgsql 

FOR loops are giving weird syntax errors.  Restructure parsing of FOR
loops so that the integer-loop-vs-query-loop decision is driven off
the presence of '..' between IN and LOOP, rather than the presence
of a matching record/row variable name.  Hopefully this will make the
behavior a bit more transparent.
parent f5c798ee
Hide whitespace changes
Inline Side-by-side
Showing with 220 additions and 139 deletions
doc/src/sgml/plpgsql.sgml
View file @ a72dd7a9
<!--
$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.38 2004/05/16 23:22:06 neilc Exp $
$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.39 2004/07/04 02:48:52 tgl Exp $
-->
<chapter id="plpgsql">
......@@ -1769,7 +1769,7 @@ END;
<para>
The <literal>FOR-IN-EXECUTE</> statement is another way to iterate over
records:
rows:
<synopsis>
<optional>&lt;&lt;<replaceable>label</replaceable>&gt;&gt;</optional>
FOR <replaceable>record_or_row</replaceable> IN EXECUTE <replaceable>text_expression</replaceable> LOOP
......@@ -1788,13 +1788,12 @@ END LOOP;
<para>
The <application>PL/pgSQL</> parser presently distinguishes the
two kinds of <literal>FOR</> loops (integer or query result) by checking
whether the target variable mentioned just after <literal>FOR</> has been
declared as a record or row variable. If not, it's presumed to be
an integer <literal>FOR</> loop. This can cause rather nonintuitive error
messages when the true problem is, say, that one has
misspelled the variable name after the <literal>FOR</>. Typically
the complaint will be something like <literal>missing ".." at end of SQL
expression</>.
whether <literal>..</> appears outside any parentheses between
<literal>IN</> and <literal>LOOP</>. If <literal>..</> is not seen then
the loop is presumed to be a loop over rows. Mistyping the <literal>..</>
is thus likely to lead to a complaint along the lines of
<quote>loop variable of loop over rows must be a record or row</>,
rather than the simple syntax error one might expect to get.
</para>
</note>
</sect2>
......
src/pl/plpgsql/src/gram.y
View file @ a72dd7a9
......@@ -4,7 +4,7 @@
* procedural language
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.56 2004/06/04 02:37:06 tgl Exp $
* $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.57 2004/07/04 02:49:04 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
......@@ -40,9 +40,11 @@
static PLpgSQL_expr *read_sql_construct(int until,
int until2,
const char *expected,
bool isexpression,
const char *sqlstart);
const char *sqlstart,
int *endtoken);
static PLpgSQL_expr *read_sql_stmt(const char *sqlstart);
static PLpgSQL_type *read_datatype(int tok);
static PLpgSQL_stmt *make_select_stmt(void);
......@@ -73,9 +75,11 @@ static void check_assignable(PLpgSQL_datum *datum);
} dtlist;
struct
{
int reverse;
PLpgSQL_expr *expr;
} forilow;
char *name;
int lineno;
PLpgSQL_rec *rec;
PLpgSQL_row *row;
} forvariable;
struct
{
char *label;
......@@ -110,11 +114,10 @@ static void check_assignable(PLpgSQL_datum *datum);
%type <expr> opt_exitcond
%type <ival> assign_var cursor_variable
%type <var> fori_var cursor_varptr
%type <var> cursor_varptr
%type <variable> decl_cursor_arg
%type <varname> fori_varname
%type <forilow> fori_lower
%type <rec> fors_target
%type <forvariable> for_variable
%type <stmt> for_control
%type <str> opt_lblname opt_label
%type <str> opt_exitlabel
......@@ -124,8 +127,8 @@ static void check_assignable(PLpgSQL_datum *datum);
%type <stmt> proc_stmt pl_block
%type <stmt> stmt_assign stmt_if stmt_loop stmt_while stmt_exit
%type <stmt> stmt_return stmt_return_next stmt_raise stmt_execsql
%type <stmt> stmt_fori stmt_fors stmt_select stmt_perform
%type <stmt> stmt_dynexecute stmt_dynfors stmt_getdiag
%type <stmt> stmt_for stmt_select stmt_perform
%type <stmt> stmt_dynexecute stmt_getdiag
%type <stmt> stmt_open stmt_fetch stmt_close
%type <intlist> raise_params
......@@ -616,9 +619,7 @@ proc_stmt : pl_block ';'
{ $$ = $1; }
| stmt_while
{ $$ = $1; }
| stmt_fori
{ $$ = $1; }
| stmt_fors
| stmt_for
{ $$ = $1; }
| stmt_select
{ $$ = $1; }
......@@ -634,8 +635,6 @@ proc_stmt : pl_block ';'
{ $$ = $1; }
| stmt_dynexecute
{ $$ = $1; }
| stmt_dynfors
{ $$ = $1; }
| stmt_perform
{ $$ = $1; }
| stmt_getdiag
......@@ -882,152 +881,218 @@ stmt_while : opt_label K_WHILE lno expr_until_loop loop_body
}
;
stmt_fori : opt_label K_FOR lno fori_var K_IN fori_lower expr_until_loop loop_body
stmt_for : opt_label K_FOR for_control loop_body
{
PLpgSQL_stmt_fori *new;
/* This runs after we've scanned the loop body */
if ($3->cmd_type == PLPGSQL_STMT_FORI)
{
PLpgSQL_stmt_fori *new;
new = malloc(sizeof(PLpgSQL_stmt_fori));
memset(new, 0, sizeof(PLpgSQL_stmt_fori));
new = (PLpgSQL_stmt_fori *) $3;
new->label = $1;
new->body = $4;
$$ = (PLpgSQL_stmt *) new;
}
else if ($3->cmd_type == PLPGSQL_STMT_FORS)
{
PLpgSQL_stmt_fors *new;
new->cmd_type = PLPGSQL_STMT_FORI;
new->lineno = $3;
new->label = $1;
new->var = $4;
new->reverse = $6.reverse;
new->lower = $6.expr;
new->upper = $7;
new->body = $8;
new = (PLpgSQL_stmt_fors *) $3;
new->label = $1;
new->body = $4;
$$ = (PLpgSQL_stmt *) new;
}
else
{
PLpgSQL_stmt_dynfors *new;
plpgsql_ns_pop();
Assert($3->cmd_type == PLPGSQL_STMT_DYNFORS);
new = (PLpgSQL_stmt_dynfors *) $3;
new->label = $1;
new->body = $4;
$$ = (PLpgSQL_stmt *) new;
}
$$ = (PLpgSQL_stmt *)new;
/* close namespace started in opt_label */
plpgsql_ns_pop();
}
;
fori_var : fori_varname
for_control : lno for_variable K_IN
{
PLpgSQL_var *new;
int tok;
bool reverse = false;
bool execute = false;
PLpgSQL_expr *expr1;
new = (PLpgSQL_var *)
plpgsql_build_variable($1.name, $1.lineno,
plpgsql_build_datatype(INT4OID,
-1),
true);
/* check for REVERSE and EXECUTE */
tok = yylex();
if (tok == K_REVERSE)
{
reverse = true;
tok = yylex();
}
plpgsql_add_initdatums(NULL);
if (tok == K_EXECUTE)
execute = true;
else
plpgsql_push_back_token(tok);
$$ = new;
}
;
/* Collect one or two expressions */
expr1 = read_sql_construct(K_DOTDOT,
K_LOOP,
"LOOP",
true,
"SELECT ",
&tok);
fori_varname : T_SCALAR
{
char *name;
if (tok == K_DOTDOT)
{
/* Found .., so it must be an integer loop */
PLpgSQL_stmt_fori *new;
PLpgSQL_expr *expr2;
PLpgSQL_var *fvar;
plpgsql_convert_ident(yytext, &name, 1);
/* name should be malloc'd for use as varname */
$$.name = strdup(name);
$$.lineno = plpgsql_scanner_lineno();
pfree(name);
}
| T_WORD
{
char *name;
expr2 = plpgsql_read_expression(K_LOOP, "LOOP");
plpgsql_convert_ident(yytext, &name, 1);
/* name should be malloc'd for use as varname */
$$.name = strdup(name);
$$.lineno = plpgsql_scanner_lineno();
pfree(name);
}
;
if (execute)
{
plpgsql_error_lineno = $1;
yyerror("cannot specify EXECUTE in integer for-loop");
}
fori_lower :
{
int tok;
/* name should be malloc'd for use as varname */
fvar = (PLpgSQL_var *)
plpgsql_build_variable(strdup($2.name),
$2.lineno,
plpgsql_build_datatype(INT4OID,
-1),
true);
tok = yylex();
if (tok == K_REVERSE)
{
$$.reverse = 1;
/* put the for-variable into the local block */
plpgsql_add_initdatums(NULL);
new = malloc(sizeof(PLpgSQL_stmt_fori));
memset(new, 0, sizeof(PLpgSQL_stmt_fori));
new->cmd_type = PLPGSQL_STMT_FORI;
new->lineno = $1;
new->var = fvar;
new->reverse = reverse;
new->lower = expr1;
new->upper = expr2;
$$ = (PLpgSQL_stmt *) new;
}
else
else if (execute)
{
$$.reverse = 0;
plpgsql_push_back_token(tok);
}
/* No .., so it must be a loop over rows */
PLpgSQL_stmt_dynfors *new;
$$.expr = plpgsql_read_expression(K_DOTDOT, "..");
}
;
if (reverse)
{
plpgsql_error_lineno = $1;
yyerror("cannot specify REVERSE in loop over rows");
}
stmt_fors : opt_label K_FOR lno fors_target K_IN K_SELECT expr_until_loop loop_body
{
PLpgSQL_stmt_fors *new;
new = malloc(sizeof(PLpgSQL_stmt_dynfors));
memset(new, 0, sizeof(PLpgSQL_stmt_dynfors));
new = malloc(sizeof(PLpgSQL_stmt_fors));
memset(new, 0, sizeof(PLpgSQL_stmt_fors));
new->cmd_type = PLPGSQL_STMT_DYNFORS;
new->lineno = $1;
if ($2.rec)
new->rec = $2.rec;
else if ($2.row)
new->row = $2.row;
else
{
plpgsql_error_lineno = $1;
yyerror("loop variable of loop over rows must be a record or row variable");
}
new->query = expr1;
new->cmd_type = PLPGSQL_STMT_FORS;
new->lineno = $3;
new->label = $1;
switch ($4->dtype)
{
case PLPGSQL_DTYPE_REC:
new->rec = $4;
break;
case PLPGSQL_DTYPE_ROW:
new->row = (PLpgSQL_row *)$4;
break;
default:
elog(ERROR, "unrecognized dtype: %d",
$4->dtype);
$$ = (PLpgSQL_stmt *) new;
}
new->query = $7;
new->body = $8;
else
{
/* No .., so it must be a loop over rows */
PLpgSQL_stmt_fors *new;
char *newquery;
plpgsql_ns_pop();
if (reverse)
{
plpgsql_error_lineno = $1;
yyerror("cannot specify REVERSE in loop over rows");
}
$$ = (PLpgSQL_stmt *)new;
}
;
new = malloc(sizeof(PLpgSQL_stmt_fors));
memset(new, 0, sizeof(PLpgSQL_stmt_fors));
stmt_dynfors : opt_label K_FOR lno fors_target K_IN K_EXECUTE expr_until_loop loop_body
{
PLpgSQL_stmt_dynfors *new;
new->cmd_type = PLPGSQL_STMT_FORS;
new->lineno = $1;
if ($2.rec)
new->rec = $2.rec;
else if ($2.row)
new->row = $2.row;
else
{
plpgsql_error_lineno = $1;
yyerror("loop variable of loop over rows must be a record or row variable");
}
/*
* Must get rid of the "SELECT " we prepended
* to expr1's text
*/
newquery = strdup(expr1->query + 7);
free(expr1->query);
expr1->query = newquery;
new = malloc(sizeof(PLpgSQL_stmt_dynfors));
memset(new, 0, sizeof(PLpgSQL_stmt_dynfors));
new->query = expr1;
new->cmd_type = PLPGSQL_STMT_DYNFORS;
new->lineno = $3;
new->label = $1;
switch ($4->dtype)
{
case PLPGSQL_DTYPE_REC:
new->rec = $4;
break;
case PLPGSQL_DTYPE_ROW:
new->row = (PLpgSQL_row *)$4;
break;
default:
elog(ERROR, "unrecognized dtype: %d",
$4->dtype);
$$ = (PLpgSQL_stmt *) new;
}
new->query = $7;
new->body = $8;
}
;
plpgsql_ns_pop();
for_variable : T_SCALAR
{
char *name;
$$ = (PLpgSQL_stmt *)new;
plpgsql_convert_ident(yytext, &name, 1);
$$.name = name;
$$.lineno = plpgsql_scanner_lineno();
$$.rec = NULL;
$$.row = NULL;
}
;
| T_WORD
{
char *name;
plpgsql_convert_ident(yytext, &name, 1);
$$.name = name;
$$.lineno = plpgsql_scanner_lineno();
$$.rec = NULL;
$$.row = NULL;
}
| T_RECORD
{
char *name;
fors_target : T_RECORD
{ $$ = yylval.rec; }
plpgsql_convert_ident(yytext, &name, 1);
$$.name = name;
$$.lineno = plpgsql_scanner_lineno();
$$.rec = yylval.rec;
$$.row = NULL;
}
| T_ROW
{
$$ = (PLpgSQL_rec *)(yylval.row);
char *name;
plpgsql_convert_ident(yytext, &name, 1);
$$.name = name;
$$.lineno = plpgsql_scanner_lineno();
$$.row = yylval.row;
$$.rec = NULL;
}
;
......@@ -1521,20 +1586,33 @@ lno :
PLpgSQL_expr *
plpgsql_read_expression(int until, const char *expected)
{
return read_sql_construct(until, expected, true, "SELECT ");
return read_sql_construct(until, 0, expected, true, "SELECT ", NULL);
}
static PLpgSQL_expr *
read_sql_stmt(const char *sqlstart)
{
return read_sql_construct(';', ";", false, sqlstart);
return read_sql_construct(';', 0, ";", false, sqlstart, NULL);
}
/*
* Read a SQL construct and build a PLpgSQL_expr for it.
*
* until: token code for expected terminator
* until2: token code for alternate terminator (pass 0 if none)
* expected: text to use in complaining that terminator was not found
* isexpression: whether to say we're reading an "expression" or a "statement"
* sqlstart: text to prefix to the accumulated SQL text
* endtoken: if not NULL, ending token is stored at *endtoken
* (this is only interesting if until2 isn't zero)
*/
static PLpgSQL_expr *
read_sql_construct(int until,
int until2,
const char *expected,
bool isexpression,
const char *sqlstart)
const char *sqlstart,
int *endtoken)
{
int tok;
int lno;
......@@ -1554,6 +1632,8 @@ read_sql_construct(int until,
tok = yylex();
if (tok == until && parenlevel == 0)
break;
if (tok == until2 && parenlevel == 0)
break;
if (tok == '(' || tok == '[')
parenlevel++;
else if (tok == ')' || tok == ']')
......@@ -1586,7 +1666,6 @@ read_sql_construct(int until,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("missing \"%s\" at end of SQL statement",
expected)));
break;
}
if (plpgsql_SpaceScanned)
plpgsql_dstring_append(&ds, " ");
......@@ -1616,6 +1695,9 @@ read_sql_construct(int until,
}
}
if (endtoken)
*endtoken = tok;
expr = malloc(sizeof(PLpgSQL_expr) + sizeof(int) * nparams - sizeof(int));
expr->dtype = PLPGSQL_DTYPE_EXPR;
expr->query = strdup(plpgsql_dstring_get(&ds));
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment