cue: add Value.BuildInstance method

Signed-off-by: Roger Peppe <[email protected]> Change-Id: I8305b61a881a15420df128937800a2c0ea1be5e3 Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/542769 Reviewed-by: Marcel van Lohuizen <[email protected]> Unity-Result: CUEcueckoo <[email protected]> TryBot-Result: CUEcueckoo <[email protected]>
cue-lang · Aug 31, 2022 · a552c1f · a552c1f
1 parent 351a9fb
commit a552c1f
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Showing 2 changed files with 34 additions and 6 deletions.
diff --git a/cue/types.go b/cue/types.go
@@ -26,6 +26,7 @@ import (
 	"github.com/cockroachdb/apd/v2"
 
 	"cuelang.org/go/cue/ast"
+	"cuelang.org/go/cue/build"
 	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/cue/token"
 	"cuelang.org/go/internal"
@@ -1088,6 +1089,18 @@ func (v Value) Source() ast.Node {
 	return v.v.Value().Source()
 }
 
+// If v exactly represents a package, BuildInstance returns
+// the build instance corresponding to the value; otherwise it returns nil.
+//
+// The value returned by Value.ReferencePath will commonly represent
+// a package.
+func (v Value) BuildInstance() *build.Instance {
+	if v.idx == nil {
+		return nil
+	}
+	return v.idx.GetInstanceFromNode(v.v)
+}
+
 // Err returns the error represented by v or nil v is not an error.
 func (v Value) Err() error {
 	if err := v.checkKind(v.ctx(), adt.BottomKind); err != nil {

diff --git a/cue/types_test.go b/cue/types_test.go
@@ -2858,9 +2858,10 @@ func TestTrimZeros(t *testing.T) {
 
 func TestReferencePath(t *testing.T) {
 	testCases := []struct {
-		input string
-		want  string
-		alt   string
+		input          string
+		want           string
+		wantImportPath string
+		alt            string
 	}{{
 		input: "v: w: x: _|_",
 		want:  "",
@@ -2926,8 +2927,9 @@ func TestReferencePath(t *testing.T) {
 
 		v: w: x: math.Pi
 		`,
-		want: "Pi",
-		alt:  "3.14159265358979323846264338327950288419716939937510582097494459",
+		want:           "Pi",
+		wantImportPath: "math",
+		alt:            "3.14159265358979323846264338327950288419716939937510582097494459",
 	}}
 	for _, tc := range testCases {
 		t.Run("", func(t *testing.T) {
@@ -2939,7 +2941,6 @@ func TestReferencePath(t *testing.T) {
 			if got := path.String(); got != tc.want {
 				t.Errorf("\n got %v;\nwant %v", got, tc.want)
 			}
-
 			if tc.want != "" {
 				want := "1"
 				if tc.alt != "" {
@@ -2949,6 +2950,13 @@ func TestReferencePath(t *testing.T) {
 				if v != want {
 					t.Errorf("path resolved to %s; want %s", v, want)
 				}
+				buildInst := root.BuildInstance()
+				if buildInst == nil {
+					t.Fatalf("no build instance found for reference path root")
+				}
+				if got, want := buildInst.ImportPath, tc.wantImportPath; got != want {
+					t.Errorf("unexpected import path; got %q want %q", got, want)
+				}
 			}
 
 			inst, a := v.Reference()
@@ -2970,6 +2978,13 @@ func TestReferencePath(t *testing.T) {
 	}
 }
 
+func TestZeroValueBuildInstance(t *testing.T) {
+	inst := Value{}.BuildInstance()
+	if inst != nil {
+		t.Error("unexpected non-nil instance")
+	}
+}
+
 func TestPos(t *testing.T) {
 	testCases := []struct {
 		value string