Add tests for functions in input language

Makefile

@@ -9,7 +9,7 @@ DATA_built = unit--2--3.sql unit--3.sql \
 			 unit--4--5.sql unit--5.sql \
 			 unit--5--6.sql unit--6.sql \
 			 unit--6--7.sql unit--7.sql
-REGRESS = extension tables unit binary unicode prefix units time temperature functions round derived compare aggregate iec custom
+REGRESS = extension tables unit binary unicode prefix units time temperature functions language_functions round derived compare aggregate iec custom
 # Jessie's and trusty's bison (3.0.2) is buggy, ship pregenerated .tab files
 EXTRA_CLEAN = unitparse.yy.* powers powers.o unit-*.dump # unitparse.tab.*
 

README.md

@@ -249,10 +249,11 @@ Unit values allow a fairly complex expression syntax on input.
 * operators + - * /
 * exponentiation: `expr^integer` or Unicode superscripts: `expr⁺⁻⁰¹²³⁴⁵⁶⁷⁸⁹`
 * parentheses ()
-* multiplication binds tighter than division such that `kg/s^2*A`
+* multiplication binds tighter than division such that `kg/s^2*A` and `kg/s^2 A`
   can be written without parentheses
 * `N|M` denotes a numeric fraction, e.g. `3|4`
 * use `hh:mm:ss[.sss]` for time values, e.g. `10:05:30 s`
+* functions: `sqrt(unit)`, `exp(x)`, `ln(x)`, `log2(x)`, `asin(x)`, `tan(x)`
 
 *Note: This covers the unit input parser for expressions like
 `'1|2 m / h'::unit`. PostgreSQL operators on type unit values are a separate

expected/language_functions.out

@@ -0,0 +1,62 @@
+select 'sqrt(4 m^2)'::unit;
+ unit 
+------
+ 2 m
+(1 row)
+
+select 'sqrt(-4 m^2)'::unit;
+ERROR:  cannot take square root of a negative-valued unit
+LINE 1: select 'sqrt(-4 m^2)'::unit;
+               ^
+select 'sqrt(4 m^3)'::unit;
+ERROR:  cannot take square root of a unit with odd "m" exponent
+LINE 1: select 'sqrt(4 m^3)'::unit;
+               ^
+select 'exp(1)'::unit;
+       unit       
+------------------
+ 2.71828182845905
+(1 row)
+
+select 'exp(1 A)'::unit;
+ERROR:  cannot take base-e exponent of value that is not dimension-less
+LINE 1: select 'exp(1 A)'::unit;
+               ^
+select 'ln(2.7)'::unit;
+       unit        
+-------------------
+ 0.993251773010283
+(1 row)
+
+select 'ln(-2.7)'::unit;
+ERROR:  cannot take ln of a negative-valued unit
+LINE 1: select 'ln(-2.7)'::unit;
+               ^
+select 'ln(2.7 s)'::unit;
+ERROR:  cannot take ln of value that is not dimension-less
+LINE 1: select 'ln(2.7 s)'::unit;
+               ^
+select 'asin(1)'::unit;
+      unit       
+-----------------
+ 1.5707963267949
+(1 row)
+
+select 'asin(2)'::unit;
+ERROR:  cannot asin of values outside the range -1 to 1
+LINE 1: select 'asin(2)'::unit;
+               ^
+select 'asin(1 kg)'::unit;
+ERROR:  cannot take asin of value that is not dimension-less
+LINE 1: select 'asin(1 kg)'::unit;
+               ^
+select 'tan(1)'::unit;
+      unit       
+-----------------
+ 1.5574077246549
+(1 row)
+
+select 'tan(1 mol)'::unit;
+ERROR:  cannot take tan of value that is not dimension-less
+LINE 1: select 'tan(1 mol)'::unit;
+               ^

sql/language_functions.sql

@@ -0,0 +1,17 @@
+select 'sqrt(4 m^2)'::unit;
+select 'sqrt(-4 m^2)'::unit;
+select 'sqrt(4 m^3)'::unit;
+
+select 'exp(1)'::unit;
+select 'exp(1 A)'::unit;
+
+select 'ln(2.7)'::unit;
+select 'ln(-2.7)'::unit;
+select 'ln(2.7 s)'::unit;
+
+select 'asin(1)'::unit;
+select 'asin(2)'::unit;
+select 'asin(1 kg)'::unit;
+
+select 'tan(1)'::unit;
+select 'tan(1 mol)'::unit;

unit.c

@@ -995,6 +995,10 @@ unit_ln_internal(Unit *a, Unit *result)
 	int		 i;
 
 	/* compute ln of value */
+	if (a->value < 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
+				 errmsg("cannot take ln of a negative-valued unit")));
 	result->value = log(a->value);
 
 	/* check dimension */
@@ -1014,6 +1018,10 @@ unit_log2_internal(Unit *a, Unit *result)
 	int		 i;
 
 	/* compute log2 of value */
+	if (a->value < 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
+				 errmsg("cannot take log2 of a negative-valued unit")));
 	result->value = log2(a->value);
 
 	/* check dimension */