README.md

@@ -71,6 +71,14 @@ By default, any error in parsing an event will result in the whole feed being ab
  * `StrictModeFailEvent` - skip the current event
  * `StrictModeFailAttribute` - skip parsing of the failing attribute, set the `Valid` attribute of the event to `false`
 
+### Duplicate attribute behavior
+
+The behavior when an attribute is duplicated can be customized with the `Duplicate.Mode` field. The default is to follow the configured strict mode behavior, but you can relax those rule by instructing `Gocal` to keep either the first or last value.
+
+ * `DuplicateModeFailStrict`
+ * `DuplicateModeKeepFirst`
+ * `DuplicateModeKeepLast`
+
 ## Limitations
 
 I do not pretend this abides by [RFC 5545](https://tools.ietf.org/html/rfc5545), this only covers parts I needed to be parsed for my own personal use. Among other, most property parameters are not handled by the library, and, for now, only the following properties are parsed:

attrs.go

@@ -0,0 +1,91 @@
+package gocal
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/apognu/gocal/parser"
+)
+
+// resolve() processes a line's value, taking duplicate rule into account to inform failure modes.
+// It takes as parameters:
+//   - A Gocal and Line instance
+//   - A pointer to the resulting field in the in-process event
+//   - A resolver function that parse the raw string value into the desired output type
+//   - An optional post-processing function that can modify other event attributs, if necessary
+func resolve[T comparable](gc *Gocal, l *Line, dst *T, resolve func(gc *Gocal, l *Line) (T, T, error), post func(gc *Gocal, out T)) error {
+	// Retrieve the parsed value for the field, as well as its default value
+	value, empty, err := resolve(gc, l)
+
+	if err != nil {
+		return err
+	}
+
+	// Apply duplicate attribute rule if the target attribute is not empty (note: would fail for empty string values)
+	if dst != nil && *dst != empty {
+		if gc.Duplicate.Mode == DuplicateModeFailStrict {
+			return NewDuplicateAttribute(l.Key, l.Value)
+		}
+	}
+
+	// If the value is empty or the duplicate mode allows further processing, set the value
+	if *dst == empty || gc.Duplicate.Mode == DuplicateModeKeepLast {
+		*dst = value
+
+		if post != nil && dst != nil {
+			post(gc, *dst)
+		}
+	}
+
+	return nil
+}
+
+func resolveString(gc *Gocal, l *Line) (string, string, error) {
+	return l.Value, "", nil
+}
+
+func resolveDate(gc *Gocal, l *Line) (*time.Time, *time.Time, error) {
+	d, err := parser.ParseTime(l.Value, l.Params, parser.TimeStart, false, gc.AllDayEventsTZ)
+	if err != nil {
+		return nil, nil, fmt.Errorf("could not parse: %s", err)
+	}
+
+	return d, nil, nil
+}
+
+func resolveDateEnd(gc *Gocal, l *Line) (*time.Time, *time.Time, error) {
+	d, err := parser.ParseTime(l.Value, l.Params, parser.TimeEnd, false, gc.AllDayEventsTZ)
+	if err != nil {
+		return nil, nil, fmt.Errorf("could not parse: %s", err)
+	}
+
+	return d, nil, nil
+}
+
+func resolveDuration(gc *Gocal, l *Line) (*time.Duration, *time.Duration, error) {
+	d, err := parser.ParseDuration(l.Value)
+	if err != nil {
+		return nil, nil, fmt.Errorf("could not parse: %s", err)
+	}
+
+	return d, nil, nil
+}
+
+func resolveOrganizer(gc *Gocal, l *Line) (*Organizer, *Organizer, error) {
+	o := Organizer{
+		Cn:          l.Params["CN"],
+		DirectoryDn: l.Params["DIR"],
+		Value:       l.Value,
+	}
+
+	return &o, nil, nil
+}
+
+func resolveGeo(gc *Gocal, l *Line) (*Geo, *Geo, error) {
+	lat, long, err := parser.ParseGeo(l.Value)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return &Geo{lat, long}, nil, nil
+}

go.mod

@@ -1,11 +1,11 @@
 module github.com/apognu/gocal
 
-go 1.13
+go 1.21
 
 require (
 	github.com/ChannelMeter/iso8601duration v0.0.0-20150204201828-8da3af7a2a61
 	github.com/channelmeter/iso8601duration v0.0.0-20150204201828-8da3af7a2a61 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/stretchr/testify v1.2.0
+	github.com/stretchr/testify v1.2.2
 )

go.sum

@@ -6,5 +6,5 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/testify v1.2.0 h1:LThGCOvhuJic9Gyd1VBCkhyUXmO8vKaBFvBsJ2k03rg=
-github.com/stretchr/testify v1.2.0/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=