feat: added chunk and slice operations

cabret.go

@@ -22,6 +22,9 @@ type File struct {
 	Content
 }
 
+// MetadataOnly is a mime type representing an item that only holds metadata
+const MetadataOnly = "metadata-only"
+
 type Content struct {
 	// Type for known content formats is just the mime-type
 	Type string
@@ -34,15 +37,15 @@ type Content struct {
 }
 
 type Operation interface {
-	Configure(config map[string]any) error
+	Configure(options map[string]any) error
 }
 
 type ListOperation interface {
 	Operation
-	ProcessList(contents []Content) ([]Content, error)
+	ProcessList(items []Content) ([]Content, error)
 }
 
 type ItemOperation interface {
 	Operation
-	ProcessItem(content Content) (*Content, error)
+	ProcessItem(item Content) (*Content, error)
 }

go.mod

@@ -18,8 +18,10 @@ require (
 	github.com/yuin/goldmark v1.5.3 // indirect
 	github.com/yuin/goldmark-meta v1.1.0 // indirect
 	golang.org/x/exp v0.0.0-20221217163422-3c43f8badb15 // indirect
+	golang.org/x/mod v0.7.0 // indirect
 	golang.org/x/sys v0.3.0 // indirect
 	golang.org/x/text v0.5.0 // indirect
+	golang.org/x/tools v0.4.0 // indirect
 	gopkg.in/yaml.v2 v2.3.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	gotest.tools v2.2.0+incompatible // indirect

go.sum

@@ -35,6 +35,8 @@ github.com/yuin/goldmark-meta v1.1.0 h1:pWw+JLHGZe8Rk0EGsMVssiNb/AaPMHfSRszZeUei
 github.com/yuin/goldmark-meta v1.1.0/go.mod h1:U4spWENafuA7Zyg+Lj5RqK/MF+ovMYtBvXi1lBb2VP0=
 golang.org/x/exp v0.0.0-20221217163422-3c43f8badb15 h1:5oN1Pz/eDhCpbMbLstvIPa0b/BEQo6g6nwV3pLjfM6w=
 golang.org/x/exp v0.0.0-20221217163422-3c43f8badb15/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
+golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
+golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -45,6 +47,8 @@ golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
 golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/text v0.5.0 h1:OLmvp0KP+FVG99Ct/qFiL/Fhk4zp4QQnZ7b2U+5piUM=
 golang.org/x/text v0.5.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/tools v0.4.0 h1:7mTAgkunk3fr4GAloyyCasadO6h9zSsQZbwvcaIciV4=
+golang.org/x/tools v0.4.0/go.mod h1:UE5sM2OK9E/d67R0ANs2xJizIymRP5gJU295PvKXxjQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

operation/chunk.go

@@ -0,0 +1,55 @@
+package operation
+
+import "github.com/aziis98/cabret"
+
+func init() {
+	registerType("chunk", &Chunk{})
+}
+
+// Chunk is a list operation that will group incoming items in groups of the given size
+type Chunk struct {
+	Count         int
+	SkipRemaining bool
+}
+
+func (op *Chunk) Configure(options map[string]any) error {
+	var err error
+	op.Count, err = getKey[int](options, "size")
+	if err != nil {
+		return err
+	}
+	op.SkipRemaining, err = getKey(options, "skip_remaining", false)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (op *Chunk) ProcessList(items []cabret.Content) ([]cabret.Content, error) {
+	totalPages := len(items) / op.Count
+
+	chunks := make([][]cabret.Content, totalPages, totalPages+1)
+
+	for i := 0; i < totalPages; i++ {
+		chunks = append(chunks, items[i*op.Count:(i+1)*op.Count])
+	}
+
+	if !op.SkipRemaining {
+		chunks = append(chunks, items[totalPages*op.Count:])
+	}
+
+	result := make([]cabret.Content, len(chunks))
+	for i, chunk := range chunks {
+		result[i] = cabret.Content{
+			Type: cabret.MetadataOnly,
+			Metadata: cabret.Map{
+				"Page":       i + 1,
+				"TotalPages": totalPages,
+				"Items":      chunk,
+			},
+		}
+	}
+
+	return result, nil
+}

operation/slice.go

@@ -0,0 +1,62 @@
+package operation
+
+import (
+	"github.com/aziis98/cabret"
+)
+
+func init() {
+	registerType("slice", &Slice{})
+}
+
+// Slice is a [cabret.ListOperation] will return a slice of the incoming items.
+// Both indices can be negative and will wrap around the items list.
+// For example "&Slice{From: -1, To: 0}" will reverse the incoming items list.
+type Slice struct {
+	From, To int
+}
+
+// Configure will configure this operation
+//
+//	from: <start index> # inclusive, optional and defaults to the start
+//	to: <end index>     # exclusive, optional and defaults to the end
+func (op *Slice) Configure(options map[string]any) error {
+	var err error
+
+	op.From, err = getKey(options, "from", 0)
+	if err != nil {
+		return err
+	}
+	op.To, err = getKey(options, "to", -1)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (op *Slice) ProcessList(items []cabret.Content) ([]cabret.Content, error) {
+	from := op.From
+	to := op.To
+
+	if to < 0 {
+		to = to + len(items) + 1
+	}
+	if from < 0 {
+		reverse(items)
+		from = from + len(items) + 1
+		from, to = to, from
+	}
+
+	return items[from:to], nil
+}
+
+//
+// utilities
+//
+
+// reverse taken from this answer https://stackoverflow.com/questions/28058278/how-do-i-reverse-a-slice-in-go
+func reverse[S ~[]E, E any](s S) {
+	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
+		s[i], s[j] = s[j], s[i]
+	}
+}