Add regression test for various power expressions with a zero base, and

adjust source code to be more modular.

diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index defdc62..a8cd226 100644 (file)
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -14,7 +14,7 @@
  * Copyright (c) 1998-2008, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.111 2008/05/08 19:25:38 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.112 2008/05/08 22:17:54 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -5170,21 +5170,6 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
        int                     local_rscale;
        double          val;
 
-       /*
-        *      This avoids log(0) for cases of 0 raised to a non-integer.
-        *      Also, while 0 ^ 0 can be either 1 or indeterminate (error), we
-        *      treat it as one because most programming languages do this.
-        *      http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
-        */
-       if (cmp_var(base, &const_zero) == 0)
-       {
-               if (cmp_var(exp, &const_zero) == 0)
-                       set_var_from_var(&const_one, result);
-               else
-                       set_var_from_var(&const_zero, result);
-               return;
-       }
-       
        /* If exp can be represented as an integer, use power_var_int */
        if (exp->ndigits == 0 || exp->ndigits <= exp->weight + 1)
        {
@@ -5217,6 +5202,17 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
                free_var(&x);
        }
 
+       /*
+        *      This avoids log(0) for cases of 0 raised to a non-integer.
+        *      0 ^ 0 handled by power_var_int().
+        */
+       if (cmp_var(base, &const_zero) == 0)
+       {
+               set_var_from_var(&const_zero, result);
+               result->dscale = NUMERIC_MIN_SIG_DIGITS;        /* no need to round */
+               return;
+       }
+       
        init_var(&ln_base);
        init_var(&ln_num);
 
@@ -5284,6 +5280,11 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
        switch (exp)
        {
                case 0:
+                       /*
+                        *      While 0 ^ 0 can be either 1 or indeterminate (error), we
+                        *      treat it as 1 because most programming languages do this.
+                        *      http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
+                        */
                        set_var_from_var(&const_one, result);
                        result->dscale = rscale;        /* no need to round */
                        return;

diff --git a/src/test/regress/expected/float8.out b/src/test/regress/expected/float8.out
index 38d2cbf..f81d9b2 100644 (file)
--- a/src/test/regress/expected/float8.out
+++ b/src/test/regress/expected/float8.out
@@ -349,6 +349,12 @@ SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
 ERROR:  value out of range: overflow
 SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
 ERROR:  value out of range: overflow
+SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
+ ?column? 
+----------
+        2
+(1 row)
+
 SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
 ERROR:  cannot take logarithm of zero
 SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;

diff --git a/src/test/regress/sql/float8.sql b/src/test/regress/sql/float8.sql
index b4dd7be..92b6b0d 100644 (file)
--- a/src/test/regress/sql/float8.sql
+++ b/src/test/regress/sql/float8.sql
@@ -129,6 +129,8 @@ SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
 
 SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
 
+SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
+
 SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
 
 SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;