tpl: Add template function namespaces

This commit moves almost all of the template functions into separate
packages under tpl/ and adds a namespace framework.  All changes should
be backward compatible for end users, as all existing function names in
the template funcMap are left intact.

Seq and DoArithmatic have been moved out of the helpers package and into
template namespaces.

Most of the tests involved have been refactored, and many new tests have
been written.  There's still work to do, but this is a big improvement.

I got a little overzealous and added some new functions along the way:

- strings.Contains
- strings.ContainsAny
- strings.HasSuffix
- strings.TrimPrefix
- strings.TrimSuffix

Documentation is forthcoming.

Fixes #3042

2 files changed, 296 insertions, 0 deletions

diff --git a/tpl/safe/safe.go b/tpl/safe/safe.go
new file mode 100644
index 000000000..64f383703
--- /dev/null
+++ b/tpl/safe/safe.go
@@ -0,0 +1,74 @@
+// Copyright 2017 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 safe
+
+import (
+	"html/template"
+
+	"github.com/spf13/cast"
+	"github.com/spf13/hugo/helpers"
+)
+
+// New returns a new instance of the safe-namespaced template functions.
+func New() *Namespace {
+	return &Namespace{}
+}
+
+// Namespace provides template functions for the "safe" namespace.
+type Namespace struct{}
+
+// Namespace returns a pointer to the current namespace instance.
+func (ns *Namespace) Namespace() *Namespace { return ns }
+
+// CSS returns a given string as html/template CSS content.
+func (ns *Namespace) CSS(a interface{}) (template.CSS, error) {
+	s, err := cast.ToStringE(a)
+	return template.CSS(s), err
+}
+
+// HTML returns a given string as html/template HTML content.
+func (ns *Namespace) HTML(a interface{}) (template.HTML, error) {
+	s, err := cast.ToStringE(a)
+	return template.HTML(s), err
+}
+
+// HTMLAttr returns a given string as html/template HTMLAttr content.
+func (ns *Namespace) HTMLAttr(a interface{}) (template.HTMLAttr, error) {
+	s, err := cast.ToStringE(a)
+	return template.HTMLAttr(s), err
+}
+
+// JS returns the given string as a html/template JS content.
+func (ns *Namespace) JS(a interface{}) (template.JS, error) {
+	s, err := cast.ToStringE(a)
+	return template.JS(s), err
+}
+
+// JSStr returns the given string as a html/template JSStr content.
+func (ns *Namespace) JSStr(a interface{}) (template.JSStr, error) {
+	s, err := cast.ToStringE(a)
+	return template.JSStr(s), err
+}
+
+// URL returns a given string as html/template URL content.
+func (ns *Namespace) URL(a interface{}) (template.URL, error) {
+	s, err := cast.ToStringE(a)
+	return template.URL(s), err
+}
+
+// SanitizeURL returns a given string as html/template URL content.
+func (ns *Namespace) SanitizeURL(a interface{}) (string, error) {
+	s, err := cast.ToStringE(a)
+	return helpers.SanitizeURL(s), err
+}
diff --git a/tpl/safe/safe_test.go b/tpl/safe/safe_test.go
new file mode 100644
index 000000000..ae58d9784
--- /dev/null
+++ b/tpl/safe/safe_test.go
@@ -0,0 +1,222 @@
+// Copyright 2017 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 safe
+
+import (
+	"fmt"
+	"html/template"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type tstNoStringer struct{}
+
+func TestNamespace(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	assert.Equal(t, ns, ns.Namespace(), "object pointers should match")
+}
+
+func TestCSS(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{`a[href =~ "//example.com"]#foo`, template.CSS(`a[href =~ "//example.com"]#foo`)},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.CSS(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}
+
+func TestHTML(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{`Hello, <b>World</b> &amp;tc!`, template.HTML(`Hello, <b>World</b> &amp;tc!`)},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.HTML(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}
+
+func TestHTMLAttr(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{` dir="ltr"`, template.HTMLAttr(` dir="ltr"`)},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.HTMLAttr(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}
+
+func TestJS(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{`c && alert("Hello, World!");`, template.JS(`c && alert("Hello, World!");`)},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.JS(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}
+
+func TestJSStr(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{`Hello, World & O'Reilly\x21`, template.JSStr(`Hello, World & O'Reilly\x21`)},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.JSStr(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}
+
+func TestURL(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{`greeting=H%69&addressee=(World)`, template.URL(`greeting=H%69&addressee=(World)`)},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.URL(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}
+
+func TestSanitizeURL(t *testing.T) {
+	t.Parallel()
+
+	ns := New()
+
+	for i, test := range []struct {
+		a      interface{}
+		expect interface{}
+	}{
+		{"http://foo/../../bar", "http://foo/bar"},
+		// errors
+		{tstNoStringer{}, false},
+	} {
+		errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+		result, err := ns.SanitizeURL(test.a)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			require.Error(t, err, errMsg)
+			continue
+		}
+
+		require.NoError(t, err, errMsg)
+		assert.Equal(t, test.expect, result, errMsg)
+	}
+}