add show course and map names

internal/common/xslices/filter.go

@@ -0,0 +1,36 @@
+package xslices
+
+func Filter[T any](values []T, f func(T) bool) []T {
+	out := make([]T, 0, len(values))
+	for _, value := range values {
+		if f(value) {
+			out = append(out, value)
+		}
+	}
+
+	return out
+}
+
+func FilterInplace[T any](values []T, match func(T) bool) (newlen int) {
+	next := 0
+	for i := 0; i < len(values); i++ {
+		value := values[i]
+		if !match(value) {
+			continue
+		}
+
+		if next != i {
+			values[next] = value
+		}
+
+		next++
+	}
+
+	return next
+}
+
+func Not[T any](f func(T) bool) func(T) bool {
+	return func(t T) bool {
+		return !f(t)
+	}
+}

internal/common/xslices/filter_test.go

@@ -0,0 +1,52 @@
+package xslices_test
+
+import (
+	"testing"
+
+	"git.loyso.art/frx/kurious/internal/common/xslices"
+)
+
+func TestFilterInplace(t *testing.T) {
+	tt := []struct {
+		name   string
+		in     []int
+		check  func(int) bool
+		expLen int
+	}{{
+		name:   "empty",
+		in:     nil,
+		check:  nil,
+		expLen: 0,
+	}, {
+		name: "all match",
+		in:   []int{1, 2, 3},
+		check: func(int) bool {
+			return true
+		},
+		expLen: 3,
+	}, {
+		name: "all not match",
+		in:   []int{1, 2, 3},
+		check: func(int) bool {
+			return false
+		},
+		expLen: 0,
+	}, {
+		name: "some filtered out",
+		in:   []int{1, 2, 3, 4},
+		check: func(v int) bool {
+			return v%2 == 0
+		},
+		expLen: 2,
+	}}
+
+	for _, tc := range tt {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			gotLen := xslices.FilterInplace(tc.in, tc.check)
+			if gotLen != tc.expLen {
+				t.Errorf("exp %d got %d", tc.expLen, gotLen)
+			}
+		})
+	}
+}

internal/common/xslices/foreach.go

@@ -0,0 +1,7 @@
+package xslices
+
+func ForEach[T any](items []T, f func(T)) {
+	for _, item := range items {
+		f(item)
+	}
+}

internal/common/xslices/map.go

@@ -0,0 +1,10 @@
+package xslices
+
+func Map[T, U any](in []T, f func(T) U) []U {
+	out := make([]U, len(in))
+	for i, value := range in {
+		out[i] = f(value)
+	}
+
+	return out
+}