diff options
author | Bjørn Erik Pedersen <bjorn.erik.pedersen@gmail.com> | 2019-03-06 09:07:49 +0100 |
---|---|---|
committer | Bjørn Erik Pedersen <bjorn.erik.pedersen@gmail.com> | 2019-03-06 22:52:38 +0100 |
commit | 02eaddc2fbe92c26e67d9f82dd9aabecbbf2106c (patch) | |
tree | 517220ebb06a75e89d506183a621123d49ee20c6 /common/hreflect | |
parent | bdf47e8da80f87b7689badf48a6b8672c048d7e4 (diff) |
tpl/tplimpl: Fix template truth logic
Before this commit, due to a bug in Go's `text/template` package, this would print different output for typed nil interface values:
```
{{ if .AuthenticatedUser }}User is authenticated!{{ else }}{{ end }}
{{ if not .AuthenticatedUser }}{{ else }}}User is authenticated!{{ end }}
```
This commit works around this by wrapping every `if` and `with` with a custom `getif` template func with truth logic that matches `not`, `and` and `or`.
Those 3 template funcs from Go's stdlib are now pulled into Hugo's source tree and adjusted to support custom zero values, e.g. types that implement `IsZero`.
This means that you can now do:
```
{{ with .Date }}{{ . }}{{ end }}
```
And it would work as expected.
Fixes #5738
Diffstat (limited to 'common/hreflect')
-rw-r--r-- | common/hreflect/helpers.go | 91 | ||||
-rw-r--r-- | common/hreflect/helpers_test.go | 42 |
2 files changed, 133 insertions, 0 deletions
diff --git a/common/hreflect/helpers.go b/common/hreflect/helpers.go new file mode 100644 index 000000000..db7b208b5 --- /dev/null +++ b/common/hreflect/helpers.go @@ -0,0 +1,91 @@ +// Copyright 2019 The Hugo Authors. All rights reserved. +// Some functions in this file (see comments) 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 hreflect contains reflect helpers. +package hreflect + +import ( + "reflect" + + "github.com/gohugoio/hugo/common/types" +) + +// IsTruthful returns whether in represents a truthful value. +// See IsTruthfulValue +func IsTruthful(in interface{}) bool { + switch v := in.(type) { + case reflect.Value: + return IsTruthfulValue(v) + default: + return IsTruthfulValue(reflect.ValueOf(in)) + } + +} + +var zeroType = reflect.TypeOf((*types.Zeroer)(nil)).Elem() + +// IsTruthfulValue returns whether the given value has a meaningful truth value. +// This is based on template.IsTrue in Go's stdlib, but also considers +// IsZero and any interface value will be unwrapped before it's considered +// for truthfulness. +// +// Based on: +// https://github.com/golang/go/blob/178a2c42254166cffed1b25fb1d3c7a5727cada6/src/text/template/exec.go#L306 +func IsTruthfulValue(val reflect.Value) (truth bool) { + val = indirectInterface(val) + + if !val.IsValid() { + // Something like var x interface{}, never set. It's a form of nil. + return + } + + if val.Type().Implements(zeroType) { + return !val.Interface().(types.Zeroer).IsZero() + } + + switch val.Kind() { + case reflect.Array, reflect.Map, reflect.Slice, reflect.String: + truth = val.Len() > 0 + case reflect.Bool: + truth = val.Bool() + case reflect.Complex64, reflect.Complex128: + truth = val.Complex() != 0 + case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Interface: + truth = !val.IsNil() + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + truth = val.Int() != 0 + case reflect.Float32, reflect.Float64: + truth = val.Float() != 0 + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + truth = val.Uint() != 0 + case reflect.Struct: + truth = true // Struct values are always true. + default: + return + } + + return +} + +// Based on: https://github.com/golang/go/blob/178a2c42254166cffed1b25fb1d3c7a5727cada6/src/text/template/exec.go#L931 +func indirectInterface(v reflect.Value) reflect.Value { + if v.Kind() != reflect.Interface { + return v + } + if v.IsNil() { + return reflect.Value{} + } + return v.Elem() +} diff --git a/common/hreflect/helpers_test.go b/common/hreflect/helpers_test.go new file mode 100644 index 000000000..3c9179394 --- /dev/null +++ b/common/hreflect/helpers_test.go @@ -0,0 +1,42 @@ +// Copyright 2019 The Hugo Authors. 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 hreflect + +import ( + "reflect" + "testing" + "time" + + "github.com/stretchr/testify/require" +) + +func TestIsTruthful(t *testing.T) { + assert := require.New(t) + + assert.True(IsTruthful(true)) + assert.False(IsTruthful(false)) + assert.True(IsTruthful(time.Now())) + assert.False(IsTruthful(time.Time{})) +} + +func BenchmarkIsTruthFul(b *testing.B) { + v := reflect.ValueOf("Hugo") + + b.ResetTimer() + for i := 0; i < b.N; i++ { + if !IsTruthfulValue(v) { + b.Fatal("not truthful") + } + } +} |