internal/filetypes: support richer versions in IsPackage

To support package paths like `foo.com/[email protected]` and `@latest`,
we'll need to recognize those paths as packages, so change
filetypes.IsPackage to do so.

For #3618.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: If48f8821ca48680d146b9ffd778a529d19af4483
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1211883
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: rogpeppe

internal/filetypes/util.go

@@ -30,20 +30,31 @@ func IsPackage(s string) bool {
 		return false
 	}
 
-	// This goes off the assumption that file names may not have a `:` in their
-	// name in cue.
-	// A filename must have an extension or be preceded by a qualifier argument.
-	// So strings of the form foo/bar:baz, where bar is a valid identifier and
-	// absolute package
-	if p := strings.LastIndexByte(s, ':'); p > 0 {
-		if !ast.IsValidIdent(s[p+1:]) {
+	ip := ast.ParseImportPath(s)
+	if ip.ExplicitQualifier {
+		if !ast.IsValidIdent(ip.Qualifier) || strings.Contains(ip.Path, ":") || ip.Path == "-" {
+			// TODO potentially widen the scope of "file-like"
+			// paths here to include more invalid package paths?
 			return false
 		}
-		// For a non-pkg, the part before : may only be lowercase and '+'.
-		// In addition, a package necessarily must have a slash of some form.
-		return strings.ContainsAny(s[:p], `/.\`)
+		// If it's got an explicit qualifier, the path has a colon in
+		// which isn't generally allowed in CUE file names.
+		return true
+	}
+	if ip.Version != "" {
+		if strings.Contains(ip.Version, "/") {
+			// We'll definitely not allow slashes in the version string
+			// so treat it as a file name.
+			return false
+		}
+		// Looks like an explicit version suffix.
+		// Deliberately leave the syntax fairly open so that
+		// we get reasonable error messages when invalid version
+		// queries are specified.
+		return true
 	}
 
+	// No version and no qualifier.
 	// Assuming we terminate search for packages once a scoped qualifier is
 	// found, we know that any file without an extension (except maybe '-')
 	// is invalid. We can therefore assume it is a package.

internal/filetypes/util_test.go

@@ -26,10 +26,17 @@ func TestIsPackage(t *testing.T) {
 		{"../.../foo", true},
 		{".../foo", true},
 		{"./:foo", true},
+		{"[email protected]", true},
+		{"foo.bar/[email protected]", true},
+		{"foo.bar/[email protected]:foo", true},
 		{"foo.bar/foo", true},
 		{"./.foo", true},
 		{"./.foo.json", false},
-
+		{`C:\Users\somefile.cue`, false},
+		{`/foo.cue`, false},
+		{`C:somefile.cue`, false},
+		{`foo.cue:1234`, false},
+		{`foo.cue:12:13`, false},
 		// Not supported yet, but could be and isn't anything else valid.
 		{":foo", true},
 
@@ -43,7 +50,7 @@ func TestIsPackage(t *testing.T) {
 		t.Run(tc.in, func(t *testing.T) {
 			got := IsPackage(tc.in)
 			if got != tc.out {
-				t.Errorf("got %v; want %v", got, tc.out)
+				t.Errorf("%q; got %v; want %v", tc.in, got, tc.out)
 			}
 		})
 	}