Support label using regexp in directive gazelle:resolve_regexp (#1822)

* Add ability to resolve label using regexp in directive resolve_regexp

* Add unit tests and update documentation

Fix formatting

Update test

Format test

remove extra whitespace

Trigger tests

Fix space

README.rst

@@ -1008,14 +1008,17 @@ The following directives are recognized:
 |   ``import-lang`` may be omitted if it is the same as ``source-lang``.                     |
 | * ``import-string-regex`` is the regex applied to the import in the source code.           |
 |   If it matches, that import will be resolved to the label specified below.                |
-| * ``label`` is the Bazel label that Gazelle should write in ``deps``.                      |
+| * ``label`` is the Bazel label that Gazelle should write in ``deps``. The label            |
+|   can be constructed using captured strings from the subpattern matching in                |
+|   import-string-regex                                                                      |
 |                                                                                            |
 | For example:                                                                               |
 |                                                                                            |
 | .. code:: bzl                                                                              |
 |                                                                                            |
 |   # gazelle:resolve_regexp go example.com/.* //foo:go_default_library                      |
 |   # gazelle:resolve_regexp proto go foo/.*\.proto //foo:foo_go_proto                       |
+|   # gazelle:resolve_regexp proto go foo/(.*)\.proto //foo/$1:foo_rule_proto                |
 |                                                                                            |
 +---------------------------------------------------+----------------------------------------+
 | :direc:`# gazelle:go_visibility label`            | n/a                                    |

resolve/config.go

@@ -38,7 +38,8 @@ func FindRuleWithOverride(c *config.Config, imp ImportSpec, lang string) (label.
 	for i := len(rc.regexpOverrides) - 1; i >= 0; i-- {
 		o := rc.regexpOverrides[i]
 		if o.matches(imp, lang) {
-			return o.dep, true
+			dep := o.resolveRegexpDep(imp)
+			return dep, true
 		}
 	}
 	return label.NoLabel, false
@@ -62,6 +63,17 @@ func (o regexpOverrideSpec) matches(imp ImportSpec, lang string) bool {
 		(o.lang == "" || o.lang == lang)
 }
 
+func (o regexpOverrideSpec) resolveRegexpDep(imp ImportSpec) label.Label {
+
+	resolvedDepWithRegex := o.ImpRegex.ReplaceAllString(imp.Imp, o.dep.String())
+	resolvedLabel, err := label.Parse(resolvedDepWithRegex)
+	if err != nil {
+		return o.dep
+	}
+
+	return resolvedLabel
+}
+
 type resolveConfig struct {
 	overrides       map[overrideKey]label.Label
 	regexpOverrides []regexpOverrideSpec

resolve/resolve_test.go

@@ -3,9 +3,9 @@ package resolve
 import (
 	"testing"
 
-	"github.com/bazelbuild/bazel-gazelle/rule"
 	"github.com/bazelbuild/bazel-gazelle/config"
 	"github.com/bazelbuild/bazel-gazelle/label"
+	"github.com/bazelbuild/bazel-gazelle/rule"
 	"github.com/google/go-cmp/cmp"
 )
 
@@ -22,6 +22,14 @@ func TestFindRuleWithOverride_ParentTraversal(t *testing.T) {
 
 	secondChildCfg := getConfig(t, "second/child/rel", nil, rootCfg)
 
+	dualResolveRegexpCfg := getConfig(t, "dual/resolve/regexp", []rule.Directive{
+		{Key: "resolve_regexp", Value: "go ^github.com/foo/(.*)$ @com_example//$1:replacement"},
+	}, rootCfg)
+
+	multipleExpDualResolveRegexpCfg := getConfig(t, "multi/dual/resolve/regexp", []rule.Directive{
+		{Key: "resolve_regexp", Value: "go ^github.com/foo/(.*)/(.*)$ @com_example//$1/bar_sub_dir/$2:replacement"},
+	}, rootCfg)
+
 	tests := []struct {
 		name      string
 		cfg       *config.Config
@@ -86,6 +94,22 @@ func TestFindRuleWithOverride_ParentTraversal(t *testing.T) {
 			want:      getTestLabel(t, "@com_example//root:replacement"),
 			wantFound: true,
 		},
+		{
+			name:       "Target resolves to label populated by regexp",
+			cfg:        dualResolveRegexpCfg,
+			importSpec: ImportSpec{Lang: "go", Imp: "github.com/foo/foo_package"},
+			lang:       "go",
+			want:       getTestLabel(t, "@com_example//foo_package:replacement"),
+			wantFound:  true,
+		},
+		{
+			name:       "Target resolves to label populated by multipe captured regexp",
+			cfg:        multipleExpDualResolveRegexpCfg,
+			importSpec: ImportSpec{Lang: "go", Imp: "github.com/foo/foo_package/baz"},
+			lang:       "go",
+			want:       getTestLabel(t, "@com_example//foo_package/bar_sub_dir/baz:replacement"),
+			wantFound:  true,
+		}, 
 	}
 
 	for _, tt := range tests {