tpl: Add debug.Dump

Fixes #3957

tpl/debug/debug.go

@@ -0,0 +1,40 @@
+// Copyright 2020 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 debug provides template functions to help debugging templates.
+package debug
+
+import (
+	"github.com/sanity-io/litter"
+
+	"github.com/gohugoio/hugo/deps"
+)
+
+// New returns a new instance of the debug-namespaced template functions.
+func New(d *deps.Deps) *Namespace {
+	return &Namespace{}
+}
+
+// Namespace provides template functions for the "debug" namespace.
+type Namespace struct {
+}
+
+// Dump returns a object dump of val as a string.
+// Note that not every value passed to Dump will print so nicely, but
+// we'll improve on that. We recommend using the "go" Chroma lexer to format the output
+// nicely.
+// Also note that the output from Dump may change from Hugo version to the next,
+// so don't depend on a specific output.
+func (ns *Namespace) Dump(val interface{}) string {
+	return litter.Sdump(val)
+}

tpl/debug/init.go

@@ -0,0 +1,45 @@
+// Copyright 2020 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 debug
+
+import (
+	"github.com/gohugoio/hugo/deps"
+	"github.com/gohugoio/hugo/tpl/internal"
+)
+
+const name = "debug"
+
+func init() {
+	f := func(d *deps.Deps) *internal.TemplateFuncsNamespace {
+		ctx := New(d)
+
+		ns := &internal.TemplateFuncsNamespace{
+			Name:    name,
+			Context: func(args ...interface{}) interface{} { return ctx },
+		}
+
+		ns.AddMethodMapping(ctx.Dump,
+			nil,
+			[][2]string{
+				{`{{- $m := newScratch -}}
+{{- $m.Set "Hugo" "Rocks!" -}}
+{{- $m.Values | debug.Dump | safeHTML -}}`, "map[string]interface {}{\n  \"Hugo\": \"Rocks!\",\n}"},
+			},
+		)
+
+		return ns
+	}
+
+	internal.AddTemplateFuncsNamespace(f)
+}

tpl/debug/init_test.go

@@ -0,0 +1,42 @@
+// Copyright 2020 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 debug
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/htesting/hqt"
+
+	qt "github.com/frankban/quicktest"
+	"github.com/gohugoio/hugo/common/loggers"
+	"github.com/gohugoio/hugo/deps"
+	"github.com/gohugoio/hugo/tpl/internal"
+)
+
+func TestInit(t *testing.T) {
+	c := qt.New(t)
+	var found bool
+	var ns *internal.TemplateFuncsNamespace
+
+	for _, nsf := range internal.TemplateFuncsNamespaceRegistry {
+		ns = nsf(&deps.Deps{Log: loggers.NewErrorLogger()})
+		if ns.Name == name {
+			found = true
+			break
+		}
+	}
+
+	c.Assert(found, qt.Equals, true)
+	c.Assert(ns.Context(), hqt.IsSameType, &Namespace{})
+}

tpl/tplimpl/template_funcs.go

@@ -36,6 +36,7 @@ import (
 	_ "github.com/gohugoio/hugo/tpl/compare"
 	_ "github.com/gohugoio/hugo/tpl/crypto"
 	_ "github.com/gohugoio/hugo/tpl/data"
+	_ "github.com/gohugoio/hugo/tpl/debug"
 	_ "github.com/gohugoio/hugo/tpl/encoding"
 	_ "github.com/gohugoio/hugo/tpl/fmt"
 	_ "github.com/gohugoio/hugo/tpl/hugo"