Add rootpath(s) and execpath(s) functions to template expansion

In addition to the $(location) function, we now also support $(rootpath) and
$(execpath) functions.

Unfortunately, we have to do this in two places since the Skylark API for expand_location has to continue calling into LocationExpander in order to preserve its semantic contract.

Progress on #2475.

RELNOTES[NEW]:
    In addition to $(location), Bazel now also supports $(rootpath) to obtain
    the root-relative path (i.e., for runfiles locations), and $(execpath) to
    obtain the exec path (i.e., for build-time locations)

PiperOrigin-RevId: 174454119

4 files changed, 79 insertions, 40 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java b/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java
index 2577ca4248..bf8f10cc64 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java
@@ -72,20 +72,21 @@ public final class LocationExpander {
     ALLOW_DATA,
   }
 
-  private static final String LOCATION = "$(location";
+  private static final boolean EXACTLY_ONE = false;
+  private static final boolean ALLOW_MULTIPLE = true;
+
+  private static final boolean USE_ROOT_PATHS = false;
+  private static final boolean USE_EXEC_PATHS = true;
 
   private final RuleErrorConsumer ruleErrorConsumer;
-  private final Function<String, String> locationFunction;
-  private final Function<String, String> locationsFunction;
+  private final ImmutableMap<String, Function<String, String>> functions;
 
   @VisibleForTesting
   LocationExpander(
       RuleErrorConsumer ruleErrorConsumer,
-      Function<String, String> locationFunction,
-      Function<String, String> locationsFunction) {
+      Map<String, Function<String, String>> functions) {
     this.ruleErrorConsumer = ruleErrorConsumer;
-    this.locationFunction = locationFunction;
-    this.locationsFunction = locationsFunction;
+    this.functions = ImmutableMap.copyOf(functions);
   }
 
   private LocationExpander(
@@ -95,8 +96,7 @@ public final class LocationExpander {
       boolean execPaths) {
     this(
         ruleErrorConsumer,
-        new LocationFunction(root, locationMap, execPaths, false),
-        new LocationFunction(root, locationMap, execPaths, true));
+        allLocationFunctions(root, locationMap, execPaths));
   }
 
   /**
@@ -167,44 +167,40 @@ public final class LocationExpander {
     StringBuilder result = new StringBuilder(value.length());
 
     while (true) {
-      // (1) Find '$(location ' or '$(locations '.
-      Function<String, String> func = locationFunction;
-      int start = value.indexOf(LOCATION, restart);
-      int scannedLength = LOCATION.length();
-      if (start == -1 || start + scannedLength == attrLength) {
+      // (1) Find '$(<fname> '.
+      int start = value.indexOf("$(", restart);
+      if (start == -1) {
         result.append(value.substring(restart));
         break;
       }
-      if (value.charAt(start + scannedLength) == 's') {
-        scannedLength++;
-        if (start + scannedLength == attrLength) {
-          result.append(value.substring(restart));
-          break;
-        }
-        func = locationsFunction;
+      int nextWhitespace = value.indexOf(' ', start);
+      if (nextWhitespace == -1) {
+        result.append(value, restart, start + 2);
+        restart = start + 2;
+        continue;
       }
-      if (value.charAt(start + scannedLength) != ' ') {
-        result.append(value, restart, start + scannedLength);
-        restart = start + scannedLength;
+      String fname = value.substring(start + 2, nextWhitespace);
+      if (!functions.containsKey(fname)) {
+        result.append(value, restart, start + 2);
+        restart = start + 2;
         continue;
       }
 
       result.append(value, restart, start);
-      scannedLength++;
 
-      int end = value.indexOf(')', start + scannedLength);
+      int end = value.indexOf(')', nextWhitespace);
       if (end == -1) {
         reporter.report(
             String.format(
                 "unterminated $(%s) expression",
-                value.substring(start + 2, start + scannedLength - 1)));
+                value.substring(start + 2, nextWhitespace)));
         return value;
       }
 
       // (2) Call appropriate function to obtain string replacement.
-      String functionValue = value.substring(start + scannedLength, end).trim();
+      String functionValue = value.substring(nextWhitespace + 1, end).trim();
       try {
-        String replacement = func.apply(functionValue);
+        String replacement = functions.get(fname).apply(functionValue);
         result.append(replacement);
       } catch (IllegalStateException ise) {
         reporter.report(ise.getMessage());
@@ -322,6 +318,18 @@ public final class LocationExpander {
     }
   }
 
+  static ImmutableMap<String, Function<String, String>> allLocationFunctions(
+      Label root, Supplier<Map<Label, Collection<Artifact>>> locationMap, boolean execPaths) {
+    return new ImmutableMap.Builder<String, Function<String, String>>()
+        .put("location", new LocationFunction(root, locationMap, execPaths, EXACTLY_ONE))
+        .put("locations", new LocationFunction(root, locationMap, execPaths, ALLOW_MULTIPLE))
+        .put("rootpath", new LocationFunction(root, locationMap, USE_ROOT_PATHS, EXACTLY_ONE))
+        .put("rootpaths", new LocationFunction(root, locationMap, USE_ROOT_PATHS, ALLOW_MULTIPLE))
+        .put("execpath", new LocationFunction(root, locationMap, USE_EXEC_PATHS, EXACTLY_ONE))
+        .put("execpaths", new LocationFunction(root, locationMap, USE_EXEC_PATHS, ALLOW_MULTIPLE))
+        .build();
+  }
+
   /**
    * Extracts all possible target locations from target specification.
    *
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/LocationTemplateContext.java b/src/main/java/com/google/devtools/build/lib/analysis/LocationTemplateContext.java
index d2888200e0..96bb24ffe8 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/LocationTemplateContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/LocationTemplateContext.java
@@ -20,7 +20,6 @@ import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Artifact;
-import com.google.devtools.build.lib.analysis.LocationExpander.LocationFunction;
 import com.google.devtools.build.lib.analysis.LocationExpander.Options;
 import com.google.devtools.build.lib.analysis.stringtemplate.ExpansionException;
 import com.google.devtools.build.lib.analysis.stringtemplate.TemplateContext;
@@ -49,8 +48,7 @@ import javax.annotation.Nullable;
  */
 final class LocationTemplateContext implements TemplateContext {
   private final TemplateContext delegate;
-  private final Function<String, String> locationFunction;
-  private final Function<String, String> locationsFunction;
+  private final ImmutableMap<String, Function<String, String>> functions;
 
   private LocationTemplateContext(
       TemplateContext delegate,
@@ -58,8 +56,7 @@ final class LocationTemplateContext implements TemplateContext {
       Supplier<Map<Label, Collection<Artifact>>> locationMap,
       boolean execPaths) {
     this.delegate = delegate;
-    this.locationFunction = new LocationFunction(root, locationMap, execPaths, false);
-    this.locationsFunction = new LocationFunction(root, locationMap, execPaths, true);
+    this.functions = LocationExpander.allLocationFunctions(root, locationMap, execPaths);
   }
 
   private LocationTemplateContext(
@@ -98,10 +95,9 @@ final class LocationTemplateContext implements TemplateContext {
   @Override
   public String lookupFunction(String name, String param) throws ExpansionException {
     try {
-      if ("location".equals(name)) {
-        return locationFunction.apply(param);
-      } else if ("locations".equals(name)) {
-        return locationsFunction.apply(param);
+      Function<String, String> f = functions.get(name);
+      if (f != null) {
+        return f.apply(param);
       }
     } catch (IllegalStateException e) {
       throw new ExpansionException(e.getMessage(), e);
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderIntegrationTest.java b/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderIntegrationTest.java
index 6dc45745d3..a1137cd02d 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderIntegrationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderIntegrationTest.java
@@ -63,4 +63,36 @@ public class LocationExpanderIntegrationTest extends BuildViewTestCase {
 
     assertThat(result).isEqualTo("foo 'spaces/file with space A' 'spaces/file with space B' bar");
   }
+
+  @Test
+  public void otherPathExpansion() throws Exception {
+    scratch.file(
+        "expansion/BUILD",
+        "genrule(name='foo', outs=['foo.txt'], cmd='never executed')",
+        "sh_library(name='lib', srcs=[':foo'])");
+
+    LocationExpander expander = makeExpander("//expansion:lib");
+    assertThat(expander.expand("foo $(execpath :foo) bar"))
+        .matches("foo .*-out/.*/expansion/foo\\.txt bar");
+    assertThat(expander.expand("foo $(execpaths :foo) bar"))
+        .matches("foo .*-out/.*/expansion/foo\\.txt bar");
+    assertThat(expander.expand("foo $(rootpath :foo) bar"))
+        .matches("foo expansion/foo.txt bar");
+    assertThat(expander.expand("foo $(rootpaths :foo) bar"))
+        .matches("foo expansion/foo.txt bar");
+  }
+
+  @Test
+  public void otherPathMultiExpansion() throws Exception {
+    scratch.file(
+        "expansion/BUILD",
+        "genrule(name='foo', outs=['foo.txt', 'bar.txt'], cmd='never executed')",
+        "sh_library(name='lib', srcs=[':foo'])");
+
+    LocationExpander expander = makeExpander("//expansion:lib");
+    assertThat(expander.expand("foo $(execpaths :foo) bar"))
+        .matches("foo .*-out/.*/expansion/bar\\.txt .*-out/.*/expansion/foo\\.txt bar");
+    assertThat(expander.expand("foo $(rootpaths :foo) bar"))
+        .matches("foo expansion/bar.txt expansion/foo.txt bar");
+  }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java
index 7fe406660d..f49cf5901a 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java
@@ -16,10 +16,12 @@ package com.google.devtools.build.lib.analysis;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.packages.AbstractRuleErrorConsumer;
 import com.google.devtools.build.lib.packages.RuleErrorConsumer;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Function;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -60,8 +62,9 @@ public class LocationExpanderTest {
   private LocationExpander makeExpander(RuleErrorConsumer ruleErrorConsumer) throws Exception {
     return new LocationExpander(
         ruleErrorConsumer,
-        (String s) -> "one(" + s + ")",
-        (String s) -> "more(" + s + ")");
+        ImmutableMap.<String, Function<String, String>>of(
+            "location", (String s) -> "one(" + s + ")",
+            "locations", (String s) -> "more(" + s + ")"));
   }
 
   private String expand(String input) throws Exception {