App.go: recreated go doc command rendering

The goal to build our own go doc renderer requires us to reproduce
the go doc output for our code. Hence, we need to re-create the
exact output.

This patch recreates the go doc output in App.go.
Signed-off-by: (Holloway) Chew, Kean Ho <kean.ho.chew@zoralab.com>

App.go

@@ -206,9 +206,10 @@ func (c *App) buildDocsData() {
 	canva := renderer.New()
 
 	for _, v := range c.targets {
+		c.printStatus(debugTag, "---NEW FILE---")
 		canva.Process(v)
 		canva.Render()
 		canva.Clear()
-		c.printStatus(debugTag, "new file.")
+		c.printStatus(debugTag, "---END FILE---")
 	}
 }

internal/generator/Generator.go

@@ -20,13 +20,14 @@ type DocData struct {
 	IsCMD        bool
 	Package      *doc.Package
 	BuildPackage *build.Package
+	FileSet      *token.FileSet
 }
 
 // Generate is to create the Go doc data from a given Go package.
 func (d *DocData) Generate() {
-	fset := token.NewFileSet()
+	d.FileSet = token.NewFileSet()
 
-	pkgSet, err := parser.ParseDir(fset,
+	pkgSet, err := parser.ParseDir(d.FileSet,
 		d.Path,
 		func(file os.FileInfo) bool {
 			name := file.Name()

internal/renderer/Renderer.go

@@ -3,6 +3,9 @@ package renderer
 import (
 	"bytes"
 	"fmt"
+	"go/doc"
+	"go/printer"
+	"go/token"
 
 	"gitlab.com/zoralab/godocgen/internal/generator"
 )
@@ -34,9 +37,88 @@ func (c *Canva) Clear() {
 
 // Process is to process the given input data
 func (c *Canva) Process(d *generator.DocData) {
-	c.renderHeader(d)
+	c.renderHeader(d.Name)
+	c.renderSynopsis(d.Package.Doc)
+	c.renderConstants(d.Package.Consts, d.FileSet)
+	c.renderVariables(d.Package.Vars, d.FileSet)
+	c.renderFunctions(d.Package.Funcs, d.FileSet)
+	c.renderTypes(d.Package.Types, d.FileSet)
 }
 
-func (c *Canva) renderHeader(d *generator.DocData) {
-	fmt.Fprintf(c.buffer, "# %s\n", d.Name)
+func (c *Canva) renderHeader(name string) {
+	fmt.Fprintf(c.buffer, "# %s\n", name)
+}
+
+func (c *Canva) renderSynopsis(content string) {
+	fmt.Fprintf(c.buffer, "%s\n", content)
+}
+
+func (c *Canva) renderConstants(list []*doc.Value, fileSet *token.FileSet) {
+	for _, entry := range list {
+		var decl bytes.Buffer
+
+		mode := printer.TabIndent | printer.UseSpaces
+		cfg := &printer.Config{Mode: mode, Tabwidth: 8}
+		_ = cfg.Fprint(&decl, fileSet, entry.Decl)
+
+		fmt.Fprintf(c.buffer, "%s\n%s\n", decl.String(), entry.Doc)
+	}
+}
+
+func (c *Canva) renderVariables(list []*doc.Value, fileSet *token.FileSet) {
+	for _, entry := range list {
+		var decl bytes.Buffer
+
+		mode := printer.TabIndent | printer.UseSpaces
+		cfg := &printer.Config{Mode: mode, Tabwidth: 8}
+		_ = cfg.Fprint(&decl, fileSet, entry.Decl)
+
+		fmt.Fprintf(c.buffer, "%s\n%s\n", decl.String(), entry.Doc)
+	}
+}
+
+func (c *Canva) renderFunctions(list []*doc.Func, fileSet *token.FileSet) {
+	for _, entry := range list {
+		var decl bytes.Buffer
+
+		// process decl
+		mode := printer.TabIndent | printer.UseSpaces
+		cfg := &printer.Config{Mode: mode, Tabwidth: 8}
+		_ = cfg.Fprint(&decl, fileSet, entry.Decl)
+
+		// process receiver
+		receiver := " "
+		if entry.Recv != "" {
+			receiver = fmt.Sprintf("(%s) ", entry.Recv)
+		}
+
+		fmt.Fprintf(c.buffer,
+			"func %s%s\n\n%s\n%s\n",
+			receiver,
+			entry.Name,
+			decl.String(),
+			entry.Doc)
+	}
+}
+
+func (c *Canva) renderTypes(list []*doc.Type, fileSet *token.FileSet) {
+	for _, entry := range list {
+		var decl bytes.Buffer
+
+		// process decl
+		mode := printer.TabIndent | printer.UseSpaces
+		cfg := &printer.Config{Mode: mode, Tabwidth: 8}
+		_ = cfg.Fprint(&decl, fileSet, entry.Decl)
+
+		fmt.Fprintf(c.buffer,
+			"type %s\n\n%s\n\n%s\n",
+			entry.Name,
+			decl.String(),
+			entry.Doc)
+
+		c.renderConstants(entry.Consts, fileSet)
+		c.renderVariables(entry.Vars, fileSet)
+		c.renderFunctions(entry.Funcs, fileSet)
+		c.renderFunctions(entry.Methods, fileSet)
+	}
 }