Make Page an interface

The main motivation of this commit is to add a `page.Page` interface to replace the very file-oriented `hugolib.Page` struct.
This is all a preparation step for issue  #5074, "pages from other data sources".

But this also fixes a set of annoying limitations, especially related to custom output formats, and shortcodes.

Most notable changes:

* The inner content of shortcodes using the `{{%` as the outer-most delimiter will now be sent to the content renderer, e.g. Blackfriday.
  This means that any markdown will partake in the global ToC and footnote context etc.
* The Custom Output formats are now "fully virtualized". This removes many of the current limitations.
* The taxonomy list type now has a reference to the `Page` object.
  This improves the taxonomy template `.Title` situation and make common template constructs much simpler.

See #5074
Fixes #5763
Fixes #5758
Fixes #5090
Fixes #5204
Fixes #4695
Fixes #5607
Fixes #5707
Fixes #5719
Fixes #3113
Fixes #5706
Fixes #5767
Fixes #5723
Fixes #5769
Fixes #5770
Fixes #5771
Fixes #5759
Fixes #5776
Fixes #5777
Fixes #5778

1 files changed, 100 insertions, 0 deletions

diff --git a/codegen/methods_test.go b/codegen/methods_test.go
new file mode 100644
index 000000000..fad6da078
--- /dev/null
+++ b/codegen/methods_test.go
@@ -0,0 +1,100 @@
+// 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 codegen
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"reflect"
+	"testing"
+
+	"github.com/gohugoio/hugo/common/herrors"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMethods(t *testing.T) {
+
+	var (
+		zeroIE     = reflect.TypeOf((*IEmbed)(nil)).Elem()
+		zeroIEOnly = reflect.TypeOf((*IEOnly)(nil)).Elem()
+		zeroI      = reflect.TypeOf((*I)(nil)).Elem()
+	)
+
+	dir, _ := os.Getwd()
+	c := NewInspector(dir)
+
+	t.Run("MethodsFromTypes", func(t *testing.T) {
+		assert := require.New(t)
+
+		methods := c.MethodsFromTypes([]reflect.Type{zeroI}, nil)
+
+		methodsStr := fmt.Sprint(methods)
+
+		assert.Contains(methodsStr, "Method1(arg0 herrors.ErrorContext)")
+		assert.Contains(methodsStr, "Method7() interface {}")
+		assert.Contains(methodsStr, "Method0() string\n Method4() string")
+		assert.Contains(methodsStr, "MethodEmbed3(arg0 string) string\n MethodEmbed1() string")
+
+		assert.Contains(methods.Imports(), "github.com/gohugoio/hugo/common/herrors")
+	})
+
+	t.Run("EmbedOnly", func(t *testing.T) {
+		assert := require.New(t)
+
+		methods := c.MethodsFromTypes([]reflect.Type{zeroIEOnly}, nil)
+
+		methodsStr := fmt.Sprint(methods)
+
+		assert.Contains(methodsStr, "MethodEmbed3(arg0 string) string")
+
+	})
+
+	t.Run("ToMarshalJSON", func(t *testing.T) {
+		assert := require.New(t)
+
+		m, pkg := c.MethodsFromTypes(
+			[]reflect.Type{zeroI},
+			[]reflect.Type{zeroIE}).ToMarshalJSON("*page", "page")
+
+		assert.Contains(m, "method6 := p.Method6()")
+		assert.Contains(m, "Method0: method0,")
+		assert.Contains(m, "return json.Marshal(&s)")
+
+		assert.Contains(pkg, "github.com/gohugoio/hugo/common/herrors")
+		assert.Contains(pkg, "encoding/json")
+
+		fmt.Println(pkg)
+
+	})
+
+}
+
+type I interface {
+	IEmbed
+	Method0() string
+	Method4() string
+	Method1(myerr herrors.ErrorContext)
+	Method3(myint int, mystring string)
+	Method5() (string, error)
+	Method6() *net.IP
+	Method7() interface{}
+	Method8() herrors.ErrorContext
+	method2()
+	method9() os.FileInfo
+}
+
+type IEOnly interface {
+	IEmbed
+}