Add comments for functions

Author: noah

README.md

@@ -54,5 +54,4 @@ Hyphens define ranges. For example, 2000-2010 indicates every year between 2000
 
 ## Details
 
-* At this moment, the package supports only **UTC** timezone.
 * The return value of `Next` and `Prev` is zero if the pattern doesn't match in five years.

parser.go

@@ -56,6 +56,8 @@ var (
 	}
 )
 
+// MustParse returns the same result as Parse but it panic
+// when something is wrong.
 func MustParseInLocation(expr string, locName string) *Schedule {
 	loc, err := time.LoadLocation(locName)
 	if err != nil {
@@ -71,6 +73,10 @@ func MustParseInLocation(expr string, locName string) *Schedule {
 	return schdule
 }
 
+// ParseInLocation parse the expression in the location and
+// returns a new schedule representing the given spec.
+// It returns an error when loading the location is failed or
+// the syntax of the expression is wrong.
 func ParseInLocation(expr string, locName string) (*Schedule, error) {
 	loc, err := time.LoadLocation(locName)
 	if err != nil {
@@ -86,6 +92,8 @@ func ParseInLocation(expr string, locName string) (*Schedule, error) {
 	return schdule, nil
 }
 
+// MustParse returns the same result as Parse but it panic
+// when the syntax of expression is wrong.
 func MustParse(expr string) *Schedule {
 	s, err := Parse(expr)
 	if err != nil {
@@ -95,6 +103,9 @@ func MustParse(expr string) *Schedule {
 	return s
 }
 
+// Parse parses the expression and returns a new schedule representing the given spec.
+// And the default location of a schedule is "UTC".
+// It returns an error when the syntax of expression is wrong.
 func Parse(expr string) (*Schedule, error) {
 	err := verifyExpr(expr)
 	if err != nil {

schedule.go

@@ -12,6 +12,7 @@ type (
 	}
 )
 
+// Next returns the next time matched with the expression.
 func (s *Schedule) Next(t time.Time) time.Time {
 	loc := time.UTC
 	if s.Location != nil {
@@ -96,6 +97,7 @@ L:
 	return t.In(origLoc)
 }
 
+// Next returns the previous time matched with the expression.
 func (s *Schedule) Prev(t time.Time) time.Time {
 	loc := time.UTC
 	if s.Location != nil {