Add unique function

interpolation/funcs.go

@@ -26,6 +26,9 @@ var CoreFunctions = map[string]ast.Function{
 	"split":      interpolationFuncSplit(),
 	"length":     interpolationFuncLength(),
 	"jsonencode": interpolationFuncJSONEncode(),
+	"pick":       interpolationFuncPick(),
+	"omit":       interpolationFuncOmit(),
+	"unique":     interpolationFuncUnique(),
 }
 
 // interpolationFuncEnv will extract a variable out of the env

interpolation/lists.go

@@ -3,6 +3,8 @@ package interpolation
 import (
 	"fmt"
 
+	"reflect"
+
 	"github.com/hashicorp/hil/ast"
 )
 
@@ -62,3 +64,29 @@ func interpolationFuncConcat() ast.Function {
 		},
 	}
 }
+
+// interpolationFuncUnique will extract the unique values and return a list
+func interpolationFuncUnique() ast.Function {
+	return ast.Function{
+		ArgTypes:   []ast.Type{ast.TypeList},
+		ReturnType: ast.TypeList,
+		Callback: func(inputs []interface{}) (interface{}, error) {
+			list := inputs[0].([]ast.Variable)
+			result := make([]ast.Variable, 0, len(list))
+
+			for _, val := range list {
+				exists := false
+				for _, r := range result {
+					if reflect.DeepEqual(val, r) {
+						exists = true
+					}
+				}
+				if !exists {
+					result = append(result, val)
+				}
+			}
+
+			return result, nil
+		},
+	}
+}

interpolation/lists_test.go

@@ -34,7 +34,7 @@ func TestInterpolationFuncList(t *testing.T) {
 	}
 }
 
-func TestInterpoloationFuncConcat(t *testing.T) {
+func TestInterpolationFuncConcat(t *testing.T) {
 	testCases := []functionTestCase{
 		{
 			description: "Two lists combine",
@@ -93,3 +93,32 @@ func TestInterpoloationFuncConcat(t *testing.T) {
 		})
 	}
 }
+
+func TestInterpolationFuncUnique(t *testing.T) {
+	testCases := []functionTestCase{
+		{
+			description: "Extracts unique values",
+			text:        `${unique(list("1", "2", "1"))}`,
+			expectation: []interface{}{"1", "2"},
+		},
+		{
+			description: "Extract unique complex values",
+			text:        `${unique(list(list("1", "2", "3"), list("1", "2"), list("1", "2", "3")))}`,
+			expectation: []interface{}{
+				[]interface{}{"1", "2", "3"},
+				[]interface{}{"1", "2"},
+			},
+		},
+	}
+
+	uniqueTestFunc := testInterpolationFunc(keyFuncs{
+		"unique": interpolationFuncUnique,
+		"list":   interpolationFuncList,
+	})
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			uniqueTestFunc(t, tc)
+		})
+	}
+}