platform_build_blueprint/proptools/proptools.go
Colin Cross 8011768729 Add property support for pointers to bools and strings
The only append semantics for bool that result in a no-op when the zero
value is appended is to OR the two values together, but that is rarely
the desired semantics.  Add support for *bool and *string as property
types, where appending a nil pointer is a no-op.  For *bool, appending a
non-nil pointer replaces the destination with the value.  For *string,
appending a non-nil pointer appends the value.

This also provides a more reliable replacement for
ModuleContext.ContainsProperty, as the  build logic can tell that the
property was set, even if it was set by a  mutator and not by the
blueprints file, by testing against nil.

[]string already provides these semantics for lists.

Setting a *bool or *string property from a blueprints file is the same
syntax as setting a bool or a string property.
2015-11-02 13:59:12 -08:00

79 lines
1.9 KiB
Go

// Copyright 2014 Google Inc. All rights reserved.
//
// 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 proptools
import (
"reflect"
"strings"
"unicode"
"unicode/utf8"
)
func PropertyNameForField(fieldName string) string {
r, size := utf8.DecodeRuneInString(fieldName)
propertyName := string(unicode.ToLower(r))
if len(fieldName) > size {
propertyName += fieldName[size:]
}
return propertyName
}
func FieldNameForProperty(propertyName string) string {
r, size := utf8.DecodeRuneInString(propertyName)
fieldName := string(unicode.ToUpper(r))
if len(propertyName) > size {
fieldName += propertyName[size:]
}
return fieldName
}
func HasTag(field reflect.StructField, name, value string) bool {
tag := field.Tag.Get(name)
for _, entry := range strings.Split(tag, ",") {
if entry == value {
return true
}
}
return false
}
// BoolPtr returns a pointer to a new bool containing the given value.
func BoolPtr(b bool) *bool {
return &b
}
// StringPtr returns a pointer to a new string containing the given value.
func StringPtr(s string) *string {
return &s
}
// Bool takes a pointer to a bool and returns true iff the pointer is non-nil and points to a true
// value.
func Bool(b *bool) bool {
if b != nil {
return *b
}
return false
}
// String takes a pointer to a string and returns the value of the string if the pointer is non-nil,
// or an empty string.
func String(s *string) string {
if s != nil {
return *s
}
return ""
}