extract some common errs

Author: dmitriy kalinin

patch/errs.go

@@ -49,3 +49,30 @@ func (e opMissingMapKeyErr) siblingKeysErrStr() string {
 	sort.Sort(sort.StringSlice(keys))
 	return "found map keys: '" + strings.Join(keys, "', '") + "'"
 }
+
+type opMissingIndexErr struct {
+	idx int
+	obj []interface{}
+}
+
+func (e opMissingIndexErr) Error() string {
+	return fmt.Sprintf("Expected to find array index '%d' but found array of length '%d'", e.idx, len(e.obj))
+}
+
+type opMultipleMatchingIndexErr struct {
+	path Pointer
+	idxs []int
+}
+
+func (e opMultipleMatchingIndexErr) Error() string {
+	return fmt.Sprintf("Expected to find exactly one matching array item for path '%s' but found %d", e.path, len(e.idxs))
+}
+
+type opUnexpectedTokenErr struct {
+	token Token
+	path  Pointer
+}
+
+func (e opUnexpectedTokenErr) Error() string {
+	return fmt.Sprintf("Expected to not find token '%T' at path '%s'", e.token, e.path)
+}

patch/find_op.go

@@ -30,8 +30,7 @@ func (op FindOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 			if idx >= len(typedObj) {
-				errMsg := "Expected to find array index '%d' but found array of length '%d'"
-				return nil, fmt.Errorf(errMsg, idx, len(typedObj))
+				return nil, opMissingIndexErr{idx, typedObj}
 			}
 
 			if isLast {
@@ -69,8 +68,7 @@ func (op FindOp) Apply(doc interface{}) (interface{}, error) {
 				}
 			} else {
 				if len(idxs) != 1 {
-					errMsg := "Expected to find exactly one matching array item for path '%s' but found %d"
-					return nil, fmt.Errorf(errMsg, NewPointer(tokens[:i+2]), len(idxs))
+					return nil, opMultipleMatchingIndexErr{NewPointer(tokens[:i+2]), idxs}
 				}
 
 				idx := idxs[0]
@@ -113,7 +111,7 @@ func (op FindOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 		default:
-			return nil, fmt.Errorf("Expected to not find token '%T' at '%s'", token, NewPointer(tokens[:i+2]))
+			return nil, opUnexpectedTokenErr{token, NewPointer(tokens[:i+2])}
 		}
 	}
 

patch/remove_op.go

@@ -31,8 +31,7 @@ func (op RemoveOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 			if idx >= len(typedObj) {
-				errMsg := "Expected to find array index '%d' but found array of length '%d'"
-				return nil, fmt.Errorf(errMsg, idx, len(typedObj))
+				return nil, opMissingIndexErr{idx, typedObj}
 			}
 
 			if isLast {
@@ -67,8 +66,7 @@ func (op RemoveOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 			if len(idxs) != 1 {
-				errMsg := "Expected to find exactly one matching array item for path '%s' but found %d"
-				return nil, fmt.Errorf(errMsg, NewPointer(tokens[:i+2]), len(idxs))
+				return nil, opMultipleMatchingIndexErr{NewPointer(tokens[:i+2]), idxs}
 			}
 
 			idx := idxs[0]
@@ -107,7 +105,7 @@ func (op RemoveOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 		default:
-			return nil, fmt.Errorf("Expected to not find token '%T' at '%s'", token, NewPointer(tokens[:i+2]))
+			return nil, opUnexpectedTokenErr{token, NewPointer(tokens[:i+2])}
 		}
 	}
 

patch/remove_op_test.go

@@ -77,7 +77,7 @@ var _ = Describe("RemoveOp.Apply", func() {
 		_, err := RemoveOp{Path: MustNewPointerFromString("/-")}.Apply([]interface{}{})
 		Expect(err).To(HaveOccurred())
 		Expect(err.Error()).To(Equal(
-			"Expected to not find token 'patch.AfterLastIndexToken' at '/-'"))
+			"Expected to not find token 'patch.AfterLastIndexToken' at path '/-'"))
 	})
 
 	Describe("array item with matching key and value", func() {

patch/replace_op.go

@@ -32,8 +32,7 @@ func (op ReplaceOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 			if idx >= len(typedObj) {
-				errMsg := "Expected to find array index '%d' but found array of length '%d'"
-				return nil, fmt.Errorf(errMsg, idx, len(typedObj))
+				return nil, opMissingIndexErr{idx, typedObj}
 			}
 
 			if isLast {
@@ -78,8 +77,7 @@ func (op ReplaceOp) Apply(doc interface{}) (interface{}, error) {
 				// no need to change prevUpdate since matching item can only be a map
 			} else {
 				if len(idxs) != 1 {
-					errMsg := "Expected to find exactly one matching array item for path '%s' but found %d"
-					return nil, fmt.Errorf(errMsg, NewPointer(tokens[:i+2]), len(idxs))
+					return nil, opMultipleMatchingIndexErr{NewPointer(tokens[:i+2]), idxs}
 				}
 
 				idx := idxs[0]
@@ -129,7 +127,7 @@ func (op ReplaceOp) Apply(doc interface{}) (interface{}, error) {
 			}
 
 		default:
-			return nil, fmt.Errorf("Expected to not find token '%T' at '%s'", token, NewPointer(tokens[:i+2]))
+			return nil, opUnexpectedTokenErr{token, NewPointer(tokens[:i+2])}
 		}
 	}