providers: Add slice functions provider

providers/slice/slice.go

@@ -0,0 +1,65 @@
+package slice
+
+import "fmt"
+import "html/template"
+import "git.tebibyte.media/sashakoshka/step"
+
+const hiddenPrefix = "."
+
+var _ step.FuncProvider = new(Provider)
+
+// Provider provides slice functions.
+type Provider struct {
+	
+}
+
+// FuncMap fulfills the step.FuncProvider interface.
+func (this *Provider) FuncMap () template.FuncMap {
+	return template.FuncMap {
+		"sAppend": funcSAppend,
+		"iAppend": funcIAppend,
+		"fAppend": funcFAppend,
+	}
+}
+
+func funcSAppend (slice any, addition string) []string {
+	switch slice := slice.(type) {
+	case []string:
+		newSlice := make([]string, len(slice) + 1)
+		copy(newSlice, slice)
+		newSlice[len(slice)] = addition
+		return newSlice
+	case string:
+		return []string { slice, addition }
+	default:
+		return funcSAppend(fmt.Sprint(slice), addition)
+	}
+}
+
+func funcIAppend (slice any, addition int) []int {
+	switch slice := slice.(type) {
+	case []int:
+		newSlice := make([]int, len(slice) + 1)
+		copy(newSlice, slice)
+		newSlice[len(slice)] = addition
+		return newSlice
+	case int:
+		return []int { slice, addition }
+	default:
+		return funcIAppend(0, addition)
+	}
+}
+
+func funcFAppend (slice any, addition float64) []float64 {
+	switch slice := slice.(type) {
+	case []float64:
+		newSlice := make([]float64, len(slice) + 1)
+		copy(newSlice, slice)
+		newSlice[len(slice)] = addition
+		return newSlice
+	case float64:
+		return []float64 { slice, addition }
+	default:
+		return funcFAppend(0, addition)
+	}
+}