Split func for strings

Author: cam-stitt

interpolation/funcs.go

@@ -22,6 +22,7 @@ var CoreFunctions = map[string]ast.Function{
 	"max":      interpolationFuncMax(),
 	"min":      interpolationFuncMin(),
 	"contains": interpolationFuncContains(),
+	"split":    interpolationFuncSplit(),
 }
 
 // interpolationFuncEnv will extract a variable out of the env

interpolation/strings.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/hashicorp/hil"
 	"github.com/hashicorp/hil/ast"
 )
 
@@ -54,6 +55,27 @@ func interpolationFuncJoin() ast.Function {
 	}
 }
 
+// interpolationFuncSplit will split a string into substrings separated by a separator string.
+func interpolationFuncSplit() ast.Function {
+	return ast.Function{
+		ArgTypes:   []ast.Type{ast.TypeString, ast.TypeString},
+		ReturnType: ast.TypeList,
+		Callback: func(inputs []interface{}) (interface{}, error) {
+			var result []ast.Variable
+			val := inputs[0].(string)
+			sep := inputs[1].(string)
+			for _, sub := range strings.Split(val, sep) {
+				nativeVal, err := hil.InterfaceToVariable(sub)
+				if err != nil {
+					return nil, err
+				}
+				result = append(result, nativeVal)
+			}
+			return result, nil
+		},
+	}
+}
+
 // interpolationFuncReplace replaces the occurences of a value on the provided string with another value.
 // The number of occurences to replace is the last argument to the function.
 func interpolationFuncReplace() ast.Function {

interpolation/strings_test.go

@@ -164,3 +164,26 @@ func TestInterpolationFuncContains(t *testing.T) {
 		})
 	}
 }
+
+func TestInterpolationFuncSplit(t *testing.T) {
+	testCases := []functionTestCase{
+		{
+			description: "Splits into list",
+			text:        `${split("foo,bar", ",")}`,
+			expectation: []interface{}{"foo", "bar"},
+		},
+		{
+			description: "Splits even when sep not found",
+			text:        `${split("foo,bar", ":")}`,
+			expectation: []interface{}{"foo,bar"},
+		},
+	}
+
+	splitTestFunc := testInterpolationFunc(keyFuncs{"split": interpolationFuncSplit})
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			splitTestFunc(t, tc)
+		})
+	}
+}