Imported Upstream version 60upstream/60

1 files changed, 72 insertions, 0 deletions

diff --git a/doc/codelab/wiki/srcextract.go b/doc/codelab/wiki/srcextract.go
new file mode 100644
index 000000000..6b5fbcb43
--- /dev/null
+++ b/doc/codelab/wiki/srcextract.go
@@ -0,0 +1,72 @@
+package main
+
+import (
+	"bytes"
+	"flag"
+	"go/parser"
+	"go/printer"
+	"go/ast"
+	"go/token"
+	"log"
+	"template"
+	"os"
+)
+
+var (
+	srcFn   = flag.String("src", "", "source filename")
+	getName = flag.String("name", "", "func/type name to output")
+	html    = flag.Bool("html", true, "output HTML")
+	showPkg = flag.Bool("pkg", false, "show package in output")
+)
+
+func main() {
+	// handle input
+	flag.Parse()
+	if *srcFn == "" || *getName == "" {
+		flag.Usage()
+		os.Exit(2)
+	}
+	// load file
+	fs := token.NewFileSet()
+	file, err := parser.ParseFile(fs, *srcFn, nil, 0)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// create filter
+	filter := func(name string) bool {
+		return name == *getName
+	}
+	// filter
+	if !ast.FilterFile(file, filter) {
+		os.Exit(1)
+	}
+	// print the AST
+	var b bytes.Buffer
+	printer.Fprint(&b, fs, file)
+	// drop package declaration
+	if !*showPkg {
+		for {
+			c, err := b.ReadByte()
+			if c == '\n' || err != nil {
+				break
+			}
+		}
+	}
+	// drop leading newlines
+	for {
+		b, err := b.ReadByte()
+		if err != nil {
+			break
+		}
+		if b != '\n' {
+			os.Stdout.Write([]byte{b})
+			break
+		}
+	}
+	// output
+	if *html {
+		template.HTMLEscape(os.Stdout, b.Bytes())
+	} else {
+		b.WriteTo(os.Stdout)
+	}
+}