added

vendor/github.com/shurcooL/go/reflectsource/funcsource.go

@@ -0,0 +1,82 @@
+package reflectsource
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"reflect"
+	"runtime"
+
+	"github.com/shurcooL/go/printerutil"
+	"github.com/shurcooL/go/reflectfind"
+)
+
+// GetSourceAsString returns the source of the func f.
+func GetSourceAsString(f interface{}) string {
+	// No need to check for f being nil, since that's handled below.
+	fv := reflect.ValueOf(f)
+	return GetFuncValueSourceAsString(fv)
+}
+
+// GetFuncValueSourceAsString returns the source of the func value fv.
+func GetFuncValueSourceAsString(fv reflect.Value) string {
+	// Checking the kind catches cases where f was nil, resulting in fv being a zero Value (i.e. invalid kind),
+	// as well as when fv is non-func.
+	if fv.Kind() != reflect.Func {
+		return "kind not func"
+	}
+	pc := fv.Pointer()
+	if pc == 0 {
+		return "nil"
+	}
+	function := runtime.FuncForPC(pc)
+	if function == nil {
+		return "nil"
+	}
+	file, line := function.FileLine(pc)
+
+	var startIndex, endIndex int
+	{
+		b, err := ioutil.ReadFile(file)
+		if err != nil {
+			return "<file not found>"
+		}
+		startIndex, endIndex = getLineStartEndIndicies(b, line-1)
+	}
+
+	fs := token.NewFileSet()
+	fileAst, err := parser.ParseFile(fs, file, nil, 0*parser.ParseComments)
+	if err != nil {
+		return "<ParseFile failed>"
+	}
+
+	// TODO: Consider using ast.Walk() instead of custom FindFirst()
+	query := func(i interface{}) bool {
+		// TODO: Factor-out the unusual overlap check
+		if f, ok := i.(*ast.FuncLit); ok && ((startIndex <= int(f.Pos())-1 && int(f.Pos())-1 <= endIndex) || (int(f.Pos())-1 <= startIndex && startIndex <= int(f.End())-1)) {
+			return true
+		}
+		return false
+	}
+	funcAst := reflectfind.First(fileAst, query)
+
+	// If func literal wasn't found, try again looking for func declaration
+	if funcAst == nil {
+		query := func(i interface{}) bool {
+			// TODO: Factor-out the unusual overlap check
+			if f, ok := i.(*ast.FuncDecl); ok && ((startIndex <= int(f.Pos())-1 && int(f.Pos())-1 <= endIndex) || (int(f.Pos())-1 <= startIndex && startIndex <= int(f.End())-1)) {
+				return true
+			}
+			return false
+		}
+		funcAst = reflectfind.First(fileAst, query)
+	}
+
+	if funcAst == nil {
+		return fmt.Sprintf("<func src not found at %v:%v>", file, line)
+	}
+
+	return printerutil.SprintAst(fs, funcAst)
+}