From ce36bc72c9c5a762474654fcd9eeb2998a116a47 Mon Sep 17 00:00:00 2001
From: Ethan Reesor <ethan.reesor@gmail.com>
Date: Tue, 13 Apr 2021 01:30:54 -0500
Subject: [PATCH] interp: produce meaningful output for file statements

---
 go.sum                |  0
 interp/interp.go      | 38 +++++++++++++++++++++++++++
 interp/result.go      | 30 ++++++++++++++++++++++
 interp/result_test.go | 60 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 128 insertions(+)
 create mode 100644 go.sum
 create mode 100644 interp/result.go
 create mode 100644 interp/result_test.go

diff --git a/go.sum b/go.sum
new file mode 100644
index 000000000..e69de29bb
diff --git a/interp/interp.go b/interp/interp.go
index 8109fba00..3ccb726c3 100644
--- a/interp/interp.go
+++ b/interp/interp.go
@@ -500,6 +500,40 @@ func isFile(filesystem fs.FS, path string) bool {
 	return err == nil && fi.Mode().IsRegular()
 }
 
+func getFileResult(n *node) *FileResult {
+	res := new(FileResult)
+
+	n.Walk(func(n *node) bool {
+		var sres FileStatementResult
+		switch n.kind {
+		case fileStmt, importDecl, typeDecl:
+			return true
+
+		case importSpec:
+			if len(n.child) == 2 {
+				sres = &PackageImportResult{
+					Name: n.child[0].ident,
+					Path: constToString(n.child[1].rval),
+				}
+			} else {
+				sres = &PackageImportResult{Path: constToString(n.child[0].rval)}
+			}
+		case funcDecl:
+			sres = &FunctionDeclarationResult{Name: n.child[1].ident}
+		case typeSpec:
+			sres = &TypeDeclarationResult{Name: n.child[0].ident}
+		default:
+			return false
+		}
+		if sres != nil {
+			res.Statements = append(res.Statements, sres)
+		}
+		return false
+	}, nil)
+
+	return res
+}
+
 func (interp *Interpreter) eval(src, name string, inc bool) (res reflect.Value, err error) {
 	if name != "" {
 		interp.name = name
@@ -617,6 +651,10 @@ func (interp *Interpreter) eval(src, name string, inc bool) (res reflect.Value,
 		}
 	}
 
+	if root.kind == fileStmt {
+		res = reflect.ValueOf(getFileResult(root))
+	}
+
 	return res, err
 }
 
diff --git a/interp/result.go b/interp/result.go
new file mode 100644
index 000000000..3d97c7b62
--- /dev/null
+++ b/interp/result.go
@@ -0,0 +1,30 @@
+package interp
+
+// FileResult is the result of evaluating a file-like source.
+type FileResult struct {
+	Statements []FileStatementResult
+}
+
+// FileStatementResult is the result of a top-level statement in a file-like source.
+type FileStatementResult interface {
+	isFileStatementResult()
+}
+
+func (*PackageImportResult) isFileStatementResult()       {}
+func (*FunctionDeclarationResult) isFileStatementResult() {}
+func (*TypeDeclarationResult) isFileStatementResult()     {}
+
+// PackageImportResult is the result of a package import statement.
+type PackageImportResult struct {
+	Name, Path string
+}
+
+// FunctionDeclarationResult is the result of a top-level function declaration statement.
+type FunctionDeclarationResult struct {
+	Name string
+}
+
+// TypeDeclarationResult is the result of a top-level type declaration statement.
+type TypeDeclarationResult struct {
+	Name string
+}
diff --git a/interp/result_test.go b/interp/result_test.go
new file mode 100644
index 000000000..b5d556a01
--- /dev/null
+++ b/interp/result_test.go
@@ -0,0 +1,60 @@
+package interp_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/traefik/yaegi/interp"
+	"github.com/traefik/yaegi/stdlib"
+)
+
+type resultTestCase struct {
+	desc, src string
+	res       interface{}
+}
+
+func TestEvalFileResult(t *testing.T) {
+	type Results = []interp.FileStatementResult
+	type Import = interp.PackageImportResult
+	type Func = interp.FunctionDeclarationResult
+	type Type = interp.TypeDeclarationResult
+
+	i := interp.New(interp.Options{})
+	_ = i.Use(stdlib.Symbols)
+	runResultTests(t, i, []resultTestCase{
+		{desc: "bare import", src: `import "time"`, res: &Import{Path: "time"}},
+		{desc: "named import", src: `import x "time"`, res: &Import{Name: "x", Path: "time"}},
+		{desc: "multiple imports", src: "import (\ny \"time\"\nz \"fmt\"\n)", res: Results{&Import{Name: "y", Path: "time"}, &Import{Name: "z", Path: "fmt"}}},
+
+		{desc: "func", src: `func foo() { }`, res: &Func{Name: "foo"}},
+
+		{desc: "struct type", src: `type Foo struct {}`, res: &Type{Name: "Foo"}},
+	})
+}
+
+func runResultTests(t *testing.T, i *interp.Interpreter, tests []resultTestCase) {
+	t.Helper()
+
+	for _, test := range tests {
+		expected := test.res
+		if stmtResult, ok := expected.(interp.FileStatementResult); ok {
+			expected = []interp.FileStatementResult{stmtResult}
+		}
+		if stmtResults, ok := expected.([]interp.FileStatementResult); ok {
+			expected = &interp.FileResult{Statements: stmtResults}
+		}
+
+		t.Run(test.desc, func(t *testing.T) {
+			res, err := i.Eval(test.src)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !res.IsValid() {
+				t.Fatal("Result is not valid")
+			}
+			if !reflect.DeepEqual(expected, res.Interface()) {
+				t.Fatalf("Got %v, expected %v", res, expected)
+			}
+		})
+	}
+}