Replace use of text/template with string manipulations (#425)

feat: replace template with strings

Author: pgimalac

visualize.go

@@ -25,7 +25,6 @@ import (
 	"fmt"
 	"io"
 	"strconv"
-	"text/template"
 
 	"go.uber.org/dig/internal/dot"
 )
@@ -92,46 +91,6 @@ func updateGraph(dg *dot.Graph, err error) error {
 	return nil
 }
 
-var _graphTmpl = template.Must(
-	template.New("DotGraph").
-		Funcs(template.FuncMap{
-			"quote": strconv.Quote,
-		}).
-		Parse(`digraph {
-	rankdir=RL;
-	graph [compound=true];
-	{{range $g := .Groups}}
-		{{- quote .String}} [{{.Attributes}}];
-		{{range .Results}}
-			{{- quote $g.String}} -> {{quote .String}};
-		{{end}}
-	{{end -}}
-	{{range $index, $ctor := .Ctors}}
-		subgraph cluster_{{$index}} {
-			{{ with .Package }}label = {{ quote .}};
-			{{ end -}}
-
-			constructor_{{$index}} [shape=plaintext label={{quote .Name}}];
-			{{with .ErrorType}}color={{.Color}};{{end}}
-			{{range .Results}}
-				{{- quote .String}} [{{.Attributes}}];
-			{{end}}
-		}
-		{{range .Params}}
-			constructor_{{$index}} -> {{quote .String}} [ltail=cluster_{{$index}}{{if .Optional}} style=dashed{{end}}];
-		{{end}}
-		{{range .GroupParams}}
-			constructor_{{$index}} -> {{quote .String}} [ltail=cluster_{{$index}}];
-		{{end -}}
-	{{end}}
-	{{range .Failed.TransitiveFailures}}
-		{{- quote .String}} [color=orange];
-	{{end -}}
-	{{range .Failed.RootCauses}}
-		{{- quote .String}} [color=red];
-	{{end}}
-}`))
-
 // Visualize parses the graph in Container c into DOT format and writes it to
 // io.Writer w.
 func Visualize(c *Container, w io.Writer, opts ...VisualizeOption) error {
@@ -148,7 +107,66 @@ func Visualize(c *Container, w io.Writer, opts ...VisualizeOption) error {
 		}
 	}
 
-	return _graphTmpl.Execute(w, dg)
+	visualizeGraph(w, dg)
+	return nil
+}
+
+func visualizeGraph(w io.Writer, dg *dot.Graph) {
+	w.Write([]byte("digraph {\n\trankdir=RL;\n\tgraph [compound=true];\n"))
+	for _, g := range dg.Groups {
+		visualizeGroup(w, g)
+	}
+	w.Write([]byte("\t\n"))
+	for idx, c := range dg.Ctors {
+		visualizeCtor(w, idx, c)
+	}
+	for _, f := range dg.Failed.TransitiveFailures {
+		fmt.Fprintf(w, "\t%s [color=orange];\n", strconv.Quote(f.String()))
+	}
+	for _, f := range dg.Failed.RootCauses {
+		fmt.Fprintf(w, "\t%s [color=red];\n", strconv.Quote(f.String()))
+	}
+	w.Write([]byte("\t\n}"))
+}
+
+func visualizeGroup(w io.Writer, g *dot.Group) {
+	fmt.Fprintf(w, "\t%s [%s];\n", strconv.Quote(g.String()), g.Attributes())
+	for _, r := range g.Results {
+		fmt.Fprintf(w, "\t\t%s -> %s;\n", strconv.Quote(g.String()), strconv.Quote(r.String()))
+	}
+	w.Write([]byte("\t\t\n"))
+}
+
+func visualizeCtor(w io.Writer, index int, c *dot.Ctor) {
+	fmt.Fprintf(w, "\t\tsubgraph cluster_%d {\n", index)
+	w.Write([]byte("\t\t\t"))
+	if c.Package != "" {
+		fmt.Fprintf(w, "label = %s;", strconv.Quote(c.Package))
+	}
+	w.Write([]byte("\n"))
+	fmt.Fprintf(w, "\t\t\tconstructor_%d [shape=plaintext label=%s];\n", index, strconv.Quote(c.Name))
+
+	w.Write([]byte("\t\t\t"))
+	if c.ErrorType != 0 {
+		fmt.Fprintf(w, "color=%s;", c.ErrorType.Color())
+	}
+	w.Write([]byte("\n"))
+	for _, r := range c.Results {
+		fmt.Fprintf(w, "\t\t\t%s [%s];\n", strconv.Quote(r.String()), r.Attributes())
+	}
+	fmt.Fprintf(w, "\t\t\t\n\t\t}\n\t\t\n")
+	for _, p := range c.Params {
+		var optionalStyle string
+		if p.Optional {
+			optionalStyle = " style=dashed"
+		}
+
+		fmt.Fprintf(w, "\t\t\tconstructor_%d -> %s [ltail=cluster_%d%s];\n\t\t\n", index, strconv.Quote(p.String()), index, optionalStyle)
+	}
+	w.Write([]byte("\t\t\n"))
+	for _, p := range c.GroupParams {
+		fmt.Fprintf(w, "\t\t\tconstructor_%d -> %s [ltail=cluster_%d];\n\t\t\n", index, strconv.Quote(p.String()), index)
+	}
 }
 
 // CanVisualizeError returns true if the error is an errVisualizer.