starlark/types: evaluate dict predeclared support

starlark/types/evaluate.go

@@ -8,10 +8,42 @@ import (
 	"go.starlark.net/starlarkstruct"
 )
 
+// BuiltinEvaluate returns a starlak.Builtin function to evalute Starlark files.
+//
+//   outline: types
+//     functions:
+//       evaluate(filename, predeclared=None) dict
+//         Evaluates a Starlark file and returns it's global context. Kwargs may
+//         be used to set predeclared.
+//         params:
+//           filename string
+//             Name of the file to execute.
+//           predeclared? dict
+//             Defines the predeclared context for the execution. Execution does
+//             not modify this dictionary
+//
 func BuiltinEvaluate() starlark.Value {
 	return starlark.NewBuiltin("evaluate", func(t *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
 		var raw starlark.String
+		predeclared := starlark.StringDict{}
+
 		switch len(args) {
+		case 2:
+			dict, ok := args.Index(1).(*starlark.Dict)
+			if !ok {
+				return nil, fmt.Errorf("expected dict, got %s", args.Index(1).Type())
+			}
+
+			for i, key := range dict.Keys() {
+				if _, ok := key.(starlark.String); ok {
+					continue
+				}
+
+				return nil, fmt.Errorf("expected string keys in dict, got %s at index %d", key.Type(), i)
+			}
+
+			kwargs = append(dict.Items(), kwargs...)
+			fallthrough
 		case 1:
 			var ok bool
 			raw, ok = args.Index(0).(starlark.String)
@@ -22,9 +54,8 @@ func BuiltinEvaluate() starlark.Value {
 			return nil, fmt.Errorf("unexpected positional arguments count")
 		}
 
-		dict := starlark.StringDict{}
 		for _, kwarg := range kwargs {
-			dict[kwarg.Index(0).(starlark.String).GoString()] = kwarg.Index(1)
+			predeclared[kwarg.Index(0).(starlark.String).GoString()] = kwarg.Index(1)
 		}
 
 		filename := raw.GoString()
@@ -35,7 +66,7 @@ func BuiltinEvaluate() starlark.Value {
 		_, file := filepath.Split(filename)
 		name := file[:len(file)-len(filepath.Ext(file))]
 
-		global, err := starlark.ExecFile(t, filename, nil, dict)
+		global, err := starlark.ExecFile(t, filename, nil, predeclared)
 		return &starlarkstruct.Module{
 			Name:    name,
 			Members: global,

starlark/types/testdata/evaluate.star

@@ -1,6 +1,22 @@
 load("assert.star", "assert")
 
 bar = "bar"
+
+# context by kwargs
 module = evaluate("evaluate/test.star", bar=bar)
 assert.eq(str(module), '<module "test">')
 assert.eq(module.foo, bar)
+
+# context by dict
+module = evaluate("evaluate/test.star", {"bar": bar})
+assert.eq(str(module), '<module "test">')
+assert.eq(module.foo, bar)
+
+# context dict overrided by kwargs
+module = evaluate("evaluate/test.star", {"bar": bar}, bar="foo")
+assert.eq(str(module), '<module "test">')
+assert.eq(module.foo, "foo")
+
+# context dict with non strings
+def contextNonString(): evaluate("evaluate/test.star", {1: bar})
+assert.fails(contextNonString, "expected string keys in dict, got int at index 0")