Support docgen from external repository

Tested this manually with rules_python and it produces the desired results.

PiperOrigin-RevId: 679631613
Change-Id: I9caad75e40e85b07ab81fe3bbbd33a0caab744bb

src/main/java/com/google/devtools/build/docgen/DocLinkMap.java

@@ -32,18 +32,18 @@ public class DocLinkMap {
 
   // For SourceUrlMapper
   final String sourceUrlRoot;
-  final Map<String, String> labelRewrites; // Gson#fromJson ensures the map is of an ordered type
+  final Map<String, String> repoPathRewrites; // Gson#fromJson ensures the map is of an ordered type
 
   @VisibleForTesting
   DocLinkMap(
       String beRoot,
       Map<String, String> beReferences,
       String sourceUrlRoot,
-      Map<String, String> labelRewrites) {
+      Map<String, String> repoPathRewrites) {
     this.beRoot = beRoot;
     this.beReferences = beReferences;
     this.sourceUrlRoot = sourceUrlRoot;
-    this.labelRewrites = labelRewrites;
+    this.repoPathRewrites = repoPathRewrites;
   }
 
   public static DocLinkMap createFromFile(String filePath) {

src/main/java/com/google/devtools/build/docgen/SourceUrlMapper.java

@@ -26,29 +26,27 @@
  * for the corresponding source file in the source code repository.
  */
 class SourceUrlMapper {
-  // TODO(arostovtsev): eventually, we will want to support multiple URL roots (e.g. for
-  // language-specific rules).
   private final String sourceUrlRoot;
   private final Path inputRoot;
-  private final ImmutableMap<String, String> labelRewrites;
+  private final ImmutableMap<String, String> repoPathsRewrites;
 
   /**
    * @param sourceUrlRoot root URL for the source code repository
    * @param inputRoot input directory corresponding to the source tree root
-   * @param labelRewrites an ordered map of label string prefixes; a map entry of the form "foo" ->
-   *     "bar" indicates that if a label string starts with "foo", that prefix should be replaced
-   *     with "bar". The intended use case is transforming labels of .bzl files in @_builtins, whose
-   *     corresponding source files live elsewhere in the repo.
+   * @param repoPathsRewrites an ordered map of repo path prefixes; A repo path is a string formed
+   *     by concatenation of @repo// and a path. This handles labels from @builtins as well as from
+   *     external * repositories. A map entry of the form "foo" -> "bar" indicates that if a repo
+   *     path starts with "foo", that prefix should be replaced with "bar" to form a full url.
    */
   SourceUrlMapper(
-      String sourceUrlRoot, String inputRoot, ImmutableMap<String, String> labelRewrites) {
+      String sourceUrlRoot, String inputRoot, ImmutableMap<String, String> repoPathsRewrites) {
     this.sourceUrlRoot = sourceUrlRoot;
     this.inputRoot = new File(inputRoot).toPath();
-    this.labelRewrites = labelRewrites;
+    this.repoPathsRewrites = repoPathsRewrites;
   }
 
   SourceUrlMapper(DocLinkMap linkMap, String inputRoot) {
-    this(linkMap.sourceUrlRoot, inputRoot, ImmutableMap.copyOf(linkMap.labelRewrites));
+    this(linkMap.sourceUrlRoot, inputRoot, ImmutableMap.copyOf(linkMap.repoPathRewrites));
   }
 
   /**
@@ -68,37 +66,40 @@ String urlOfFile(File file) {
    * Returns the source code repository URL of a .bzl file label which was passed as an input to the
    * Build Encyclopedia generator tool.
    *
-   * <p>A label is first rewritten via {@link labelRewrites}: an entry of the form "foo" -> "bar"
-   * means that if {@code labelString} starts with "foo", the "foo" prefix is replaced with "bar".
-   * Rewrite rules in {@link labelRewrites} are examined in order, and only the first matching
-   * rewrite is applied.
+   * <p>A label is first rewritten via {@link repoPathsRewrites}: an entry of the form "foo" ->
+   * "bar" means that if {@code labelString} starts with "foo", the "foo" prefix is replaced with
+   * "bar". Rewrite rules in {@link repoPathsRewrites} are examined in order, and only the first
+   * matching rewrite is applied.
    *
    * <p>If the result is a label in the main repo, the (possibly rewritten) label is transformed
    * into a URL.
    *
    * @throws InvalidArgumentException if the URL could not be produced.
    */
   String urlOfLabel(String labelString) {
-    String originalLabelString = labelString;
-    for (Map.Entry<String, String> entry : labelRewrites.entrySet()) {
-      if (labelString.startsWith(entry.getKey())) {
-        labelString = entry.getValue() + labelString.substring(entry.getKey().length());
-        break;
-      }
-    }
     Label label;
     try {
       label = Label.parseCanonical(labelString);
     } catch (LabelSyntaxException e) {
       String message = String.format("Failed to parse label '%s'", labelString);
-      if (!labelString.equals(originalLabelString)) {
-        message = String.format("%s (rewritten; originally '%s')", message, originalLabelString);
-      }
       throw new IllegalArgumentException(message, e);
     }
-    Preconditions.checkArgument(
-        label.getRepository().isMain(), "Label '%s' is not in the main repository", labelString);
+    return urlOfLabel(label);
+  }
+
+  private String urlOfLabel(Label label) {
+    String path =
+        "@"
+            + label.getPackageIdentifier().getRepository().getName()
+            + "//"
+            + label.toPathFragment().getPathString();
+    for (Map.Entry<String, String> entry : repoPathsRewrites.entrySet()) {
+      if (path.startsWith(entry.getKey())) {
+        path = entry.getValue() + path.substring(entry.getKey().length());
+        break;
+      }
+    }
 
-    return sourceUrlRoot + label.toPathFragment().getPathString();
+    return path;
   }
 }

src/main/java/com/google/devtools/build/docgen/bazel_link_map.json

@@ -23,7 +23,9 @@
     "visibility": "/concepts/visibility"
   },
   "sourceUrlRoot": "https://github.com/bazelbuild/bazel/blob/master/",
-  "labelRewrites": {
-    "@@_builtins//:": "//src/main/starlark/builtins_bzl:"
+  "repoPathRewrites": {
+    "@//": "https://github.com/bazelbuild/bazel/blob/master/",
+    "@_builtins//": "https://github.com/bazelbuild/bazel/blob/master/src/main/starlark/builtins_bzl/",
+    "@rules_python//": "https://github.com/bazelbuild/rules_python/blob/main/"
   }
 }

src/test/java/com/google/devtools/build/docgen/BuildDocCollectorTest.java

@@ -48,7 +48,7 @@ public final class BuildDocCollectorTest {
       new SourceUrlMapper(
           /* sourceUrlRoot= */ "https://example.com/",
           /* inputRoot= */ "/tmp/io_bazel/",
-          ImmutableMap.of("@_builtins//:", "//src/main/starlark/builtins_bzl:"));
+          ImmutableMap.of("@_builtins//", "https://example.com/src/main/starlark/builtins_bzl/"));
 
   @Before
   public void setUpCollectorState() {

src/test/java/com/google/devtools/build/docgen/DocLinkMapTest.java

@@ -56,10 +56,10 @@ public void testCreateFromFile() throws IOException {
             + "    \"build-ref3\": \"build-ref3.html\""
             + "},"
             + "\"sourceUrlRoot\": \"https://example.com/\","
-            + "\"labelRewrites\": {"
-            + "    \"@_builtins//:common/\": \"//common/builtins_bzl:\","
-            + "    \"@_builtins//:uncommon/\": \"//uncommon/builtins_bzl:\","
-            + "    \"@_builtins//:\": \"//main/builtins_bzl:\""
+            + "\"repoPathRewrites\": {"
+            + "    \"@_builtins//common/\": \"https://example.com/common/builtins_bzl\","
+            + "    \"@_builtins//uncommon/\": \"https://example.com/uncommon/builtins_bzl\","
+            + "    \"@_builtins//\": \"https://example.com/main/builtins_bzl\""
             + "}"
             + "}";
 
@@ -78,14 +78,14 @@ public void testCreateFromFile() throws IOException {
             "build-ref3.html")
         .inOrder();
     assertThat(map.sourceUrlRoot).isEqualTo("https://example.com/");
-    assertThat(map.labelRewrites)
+    assertThat(map.repoPathRewrites)
         .containsExactly(
-            "@_builtins//:common/",
-            "//common/builtins_bzl:",
-            "@_builtins//:uncommon/",
-            "//uncommon/builtins_bzl:",
-            "@_builtins//:",
-            "//main/builtins_bzl:")
+            "@_builtins//common/",
+            "https://example.com/common/builtins_bzl",
+            "@_builtins//uncommon/",
+            "https://example.com/uncommon/builtins_bzl",
+            "@_builtins//",
+            "https://example.com/main/builtins_bzl")
         .inOrder();
   }
 }

src/test/java/com/google/devtools/build/docgen/SourceUrlMapperTest.java

@@ -32,10 +32,10 @@ public final class SourceUrlMapperTest {
           "https://example.com/",
           "/tmp/io_bazel",
           ImmutableMap.of(
-              "@_builtins//:common/",
-              "//src/common/starlark/builtins_bzl:",
-              "@_builtins//:",
-              "//src/main/starlark/builtins_bzl:"));
+              "@//",
+              "https://example.com/",
+              "@_builtins//",
+              "https://example.com/src/main/starlark/builtins_bzl/"));
 
   @Test
   public void urlOfFile() {
@@ -56,21 +56,9 @@ public void urlOfFile_throwsIfFileNotUnderSourceRoot() {
 
   @Test
   public void urlOfLabel() {
-    assertThat(mapper.urlOfLabel("@_builtins//:common/foo/bar.bzl"))
-        .isEqualTo("https://example.com/src/common/starlark/builtins_bzl/foo/bar.bzl");
     assertThat(mapper.urlOfLabel("@_builtins//:foo/bar.bzl"))
         .isEqualTo("https://example.com/src/main/starlark/builtins_bzl/foo/bar.bzl");
     assertThat(mapper.urlOfLabel("//not/in/builtins/foo:bar.bzl"))
         .isEqualTo("https://example.com/not/in/builtins/foo/bar.bzl");
   }
-
-  @Test
-  public void urlOfLabel_throwsIfLabelNotInMainRepo() {
-    IllegalArgumentException e =
-        assertThrows(
-            IllegalArgumentException.class, () -> mapper.urlOfLabel("@other_repo//foo:bar.bzl"));
-    assertThat(e)
-        .hasMessageThat()
-        .contains("Label '@other_repo//foo:bar.bzl' is not in the main repository");
-  }
 }