Migrate Sirupsen to sirupsen.

vendor/github.com/vulcand/predicate/lib.go

@@ -0,0 +1,150 @@
+/*
+Copyright 2016 Vulcand Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package predicate
+
+import (
+	"reflect"
+	"strings"
+
+	"github.com/gravitational/trace"
+)
+
+// GetStringMapValue is a helper function that returns property
+// from map[string]string or map[string][]string
+// the function returns empty value in case if key not found
+// In case if map is nil, returns empty value as well
+func GetStringMapValue(mapVal, keyVal interface{}) (interface{}, error) {
+	key, ok := keyVal.(string)
+	if !ok {
+		return nil, trace.BadParameter("only string keys are supported")
+	}
+	switch m := mapVal.(type) {
+	case map[string][]string:
+		if len(m) == 0 {
+			// to return nil with a proper type
+			var n []string
+			return n, nil
+		}
+		return m[key], nil
+	case map[string]string:
+		if len(m) == 0 {
+			return "", nil
+		}
+		return m[key], nil
+	default:
+		return nil, trace.BadParameter("type %T is not supported", m)
+	}
+}
+
+// BoolPredicate is a function without arguments that returns
+// boolean value when called
+type BoolPredicate func() bool
+
+// Equals can compare complex objects, e.g. arrays of strings
+// and strings together
+func Equals(a interface{}, b interface{}) BoolPredicate {
+	return func() bool {
+		switch aval := a.(type) {
+		case string:
+			bval, ok := b.(string)
+			return ok && aval == bval
+		case []string:
+			bval, ok := b.([]string)
+			if !ok {
+				return false
+			}
+			if len(aval) != len(bval) {
+				return false
+			}
+			for i := range aval {
+				if aval[i] != bval[i] {
+					return false
+				}
+			}
+			return true
+		default:
+			return false
+		}
+	}
+}
+
+// Contains checks if string slice contains a string
+// Contains([]string{"a", "b"}, "b") -> true
+func Contains(a interface{}, b interface{}) BoolPredicate {
+	return func() bool {
+		aval, ok := a.([]string)
+		if !ok {
+			return false
+		}
+		bval, ok := b.(string)
+		if !ok {
+			return false
+		}
+		for _, v := range aval {
+			if v == bval {
+				return true
+			}
+		}
+		return false
+	}
+}
+
+// And is a boolean predicate that calls two boolean predicates
+// and returns result of && operation on their return values
+func And(a, b BoolPredicate) BoolPredicate {
+	return func() bool {
+		return a() && b()
+	}
+}
+
+// Or is a boolean predicate that calls two boolean predicates
+// and returns result of || operation on their return values
+func Or(a, b BoolPredicate) BoolPredicate {
+	return func() bool {
+		return a() || b()
+	}
+}
+
+// GetFieldByTag returns a field from the object based on the tag
+func GetFieldByTag(ival interface{}, tagName string, fieldNames []string) (interface{}, error) {
+	if len(fieldNames) == 0 {
+		return nil, trace.BadParameter("missing field names")
+	}
+	val := reflect.ValueOf(ival)
+	if val.Kind() == reflect.Interface || val.Kind() == reflect.Ptr {
+		val = val.Elem()
+	}
+	if val.Kind() != reflect.Struct {
+		return nil, trace.NotFound("field name %v is not found", strings.Join(fieldNames, "."))
+	}
+	fieldName := fieldNames[0]
+	rest := fieldNames[1:]
+
+	valType := val.Type()
+	for i := 0; i < valType.NumField(); i++ {
+		tagValue := valType.Field(i).Tag.Get(tagName)
+		parts := strings.Split(tagValue, ",")
+		if parts[0] == fieldName {
+			value := val.Field(i).Interface()
+			if len(rest) == 0 {
+				return value, nil
+			}
+			return GetFieldByTag(value, tagName, rest)
+		}
+	}
+	return nil, trace.NotFound("field name %v is not found", strings.Join(fieldNames, "."))
+}