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Diffstat (limited to 'tpl/compare/truth.go')
-rw-r--r-- | tpl/compare/truth.go | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/tpl/compare/truth.go b/tpl/compare/truth.go new file mode 100644 index 000000000..85ee22121 --- /dev/null +++ b/tpl/compare/truth.go @@ -0,0 +1,73 @@ +// Copyright 2019 The Hugo Authors. All rights reserved. +// The functions in this file is based on the Go source code, copyright +// The Go Authors and governed by a BSD-style license. +// +// 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 compare provides template functions for comparing values. +package compare + +import ( + "reflect" + + "github.com/gohugoio/hugo/common/hreflect" +) + +// Boolean logic, based on: +// https://github.com/golang/go/blob/178a2c42254166cffed1b25fb1d3c7a5727cada6/src/text/template/funcs.go#L302 + +func truth(arg reflect.Value) bool { + return hreflect.IsTruthfulValue(arg) +} + +// getIf will return the given arg if it is considered truthful, else an empty string. +func (*Namespace) getIf(arg reflect.Value) reflect.Value { + if truth(arg) { + return arg + } + return reflect.ValueOf("") +} + +// And computes the Boolean AND of its arguments, returning +// the first false argument it encounters, or the last argument. +func (*Namespace) And(arg0 reflect.Value, args ...reflect.Value) reflect.Value { + if !truth(arg0) { + return arg0 + } + for i := range args { + arg0 = args[i] + if !truth(arg0) { + break + } + } + return arg0 +} + +// Or computes the Boolean OR of its arguments, returning +// the first true argument it encounters, or the last argument. +func (*Namespace) Or(arg0 reflect.Value, args ...reflect.Value) reflect.Value { + if truth(arg0) { + return arg0 + } + for i := range args { + arg0 = args[i] + if truth(arg0) { + break + } + } + return arg0 +} + +// Not returns the Boolean negation of its argument. +func (*Namespace) Not(arg reflect.Value) bool { + return !truth(arg) +} |