Add PolicySource

PiperOrigin-RevId: 646279818

Author: l46kok

common/BUILD.bazel

@@ -59,3 +59,9 @@ java_library(
     name = "proto_json_adapter",
     exports = ["//common/src/main/java/dev/cel/common:proto_json_adapter"],
 )
+
+java_library(
+    name = "source",
+    visibility = ["//visibility:public"],
+    exports = ["//common/src/main/java/dev/cel/common:source"],
+)

common/src/main/java/dev/cel/common/BUILD.bazel

@@ -39,6 +39,7 @@ java_library(
     ],
     deps = [
         ":error_codes",
+        ":source",
         "//:auto_value",
         "//common/annotations",
         "//common/ast",
@@ -62,6 +63,7 @@ java_library(
     ],
     deps = [
         ":common",
+        ":source",
         "//:auto_value",
         "//common/annotations",
         "//common/internal:safe_string_formatter",
@@ -175,3 +177,16 @@ java_library(
         "@maven//:com_google_protobuf_protobuf_java_util",
     ],
 )
+
+java_library(
+    name = "source",
+    srcs = [
+        "CelSourceHelper.java",
+        "Source.java",
+    ],
+    deps = [
+        "//common/annotations",
+        "//common/internal",
+        "@maven//:com_google_guava_guava",
+    ],
+)

common/src/main/java/dev/cel/common/CelIssue.java

@@ -74,7 +74,7 @@ public static CelIssue formatError(int line, int column, String message) {
   private static final char WIDE_HAT = '\uff3e';
 
   /** Returns a string representing this error that is suitable for displaying to humans. */
-  public String toDisplayString(CelSource source) {
+  public String toDisplayString(Source source) {
     // Based onhttps://github.com/google/cel-go/blob/v0.5.1/common/error.go#L42.
     String result =
         SafeStringFormatter.format(

common/src/main/java/dev/cel/common/CelSource.java

@@ -16,9 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
 
 import com.google.auto.value.AutoValue;
-import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -36,8 +36,7 @@
 
 /** Represents the source content of an expression and related metadata. */
 @Immutable
-public final class CelSource {
-  private static final Splitter LINE_SPLITTER = Splitter.on('\n');
+public final class CelSource implements Source {
 
   private final CelCodePointArray codePoints;
   private final String description;
@@ -55,10 +54,12 @@ private CelSource(Builder builder) {
     this.extensions = checkNotNull(builder.extensions.build());
   }
 
+  @Override
   public CelCodePointArray getContent() {
     return codePoints;
   }
 
+  @Override
   public String getDescription() {
     return description;
   }
@@ -109,24 +110,9 @@ public Optional<CelSourceLocation> getOffsetLocation(int offset) {
     return getOffsetLocationImpl(lineOffsets, offset);
   }
 
-  /**
-   * Get the text from the source expression that corresponds to {@code line}.
-   *
-   * @param line the line number starting from 1.
-   */
+  @Override
   public Optional<String> getSnippet(int line) {
-    checkArgument(line > 0);
-    int start = findLineOffset(lineOffsets, line);
-    if (start == -1) {
-      return Optional.empty();
-    }
-    int end = findLineOffset(lineOffsets, line + 1);
-    if (end == -1) {
-      end = codePoints.size();
-    } else {
-      end--;
-    }
-    return Optional.of(end != start ? codePoints.slice(start, end).toString() : "");
+    return CelSourceHelper.getSnippet(codePoints, line);
   }
 
   /**
@@ -140,7 +126,7 @@ private static Optional<Integer> getLocationOffsetImpl(
       List<Integer> lineOffsets, int line, int column) {
     checkArgument(line > 0);
     checkArgument(column >= 0);
-    int offset = findLineOffset(lineOffsets, line);
+    int offset = CelSourceHelper.findLineOffset(lineOffsets, line);
     if (offset == -1) {
       return Optional.empty();
     }
@@ -157,16 +143,6 @@ public static Optional<CelSourceLocation> getOffsetLocationImpl(
     return Optional.of(CelSourceLocation.of(lineAndOffset.line, offset - lineAndOffset.offset));
   }
 
-  private static int findLineOffset(List<Integer> lineOffsets, int line) {
-    if (line == 1) {
-      return 0;
-    }
-    if (line > 1 && line <= lineOffsets.size()) {
-      return lineOffsets.get(line - 2);
-    }
-    return -1;
-  }
-
   private static LineAndOffset findLine(List<Integer> lineOffsets, int offset) {
     int line = 1;
     for (int index = 0; index < lineOffsets.size(); index++) {
@@ -194,13 +170,8 @@ public static Builder newBuilder() {
   }
 
   public static Builder newBuilder(String text) {
-    List<Integer> lineOffsets = new ArrayList<>();
-    int lineOffset = 0;
-    for (String line : LINE_SPLITTER.split(text)) {
-      lineOffset += (int) (line.codePoints().count() + 1);
-      lineOffsets.add(lineOffset);
-    }
-    return new Builder(CelCodePointArray.fromString(text), lineOffsets);
+    CelCodePointArray codePointArray = CelCodePointArray.fromString(text);
+    return new Builder(codePointArray, codePointArray.lineOffsets());
   }
 
   /** Builder for {@link CelSource}. */
@@ -212,6 +183,7 @@ public static final class Builder {
     private final Map<Long, CelExpr> macroCalls;
     private final ImmutableSet.Builder<Extension> extensions;
 
+    private final boolean lineOffsetsAlreadyComputed;
     private String description;
 
     private Builder() {
@@ -225,6 +197,7 @@ private Builder(CelCodePointArray codePoints, List<Integer> lineOffsets) {
       this.macroCalls = new HashMap<>();
       this.extensions = ImmutableSet.builder();
       this.description = "";
+      this.lineOffsetsAlreadyComputed = !lineOffsets.isEmpty();
     }
 
     @CanIgnoreReturnValue
@@ -236,6 +209,9 @@ public Builder setDescription(String description) {
     @CanIgnoreReturnValue
     public Builder addLineOffsets(int lineOffset) {
       checkArgument(lineOffset >= 0);
+      checkState(
+          !lineOffsetsAlreadyComputed,
+          "Line offsets were already been computed through the provided code points.");
       lineOffsets.add(lineOffset);
       return this;
     }
@@ -362,8 +338,8 @@ private LineAndOffset(int line, int offset) {
       this.offset = offset;
     }
 
-    int line;
-    int offset;
+    private final int line;
+    private final int offset;
   }
 
   /**

common/src/main/java/dev/cel/common/CelSourceHelper.java

@@ -0,0 +1,61 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package dev.cel.common;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.collect.ImmutableList;
+import dev.cel.common.annotations.Internal;
+import dev.cel.common.internal.CelCodePointArray;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Helper methods for common source handling in CEL.
+ *
+ * <p>CEL Library Internals. Do Not Use.
+ */
+@Internal
+public final class CelSourceHelper {
+
+  /** Extract the snippet text that corresponds to {@code line}. */
+  public static Optional<String> getSnippet(CelCodePointArray content, int line) {
+    checkArgument(line > 0);
+    ImmutableList<Integer> lineOffsets = content.lineOffsets();
+    int start = findLineOffset(lineOffsets, line);
+    if (start == -1) {
+      return Optional.empty();
+    }
+    int end = findLineOffset(lineOffsets, line + 1);
+    if (end == -1) {
+      end = content.size();
+    } else {
+      end--;
+    }
+    return Optional.of(end != start ? content.slice(start, end).toString() : "");
+  }
+
+  static int findLineOffset(List<Integer> lineOffsets, int line) {
+    if (line == 1) {
+      return 0;
+    }
+    if (line > 1 && line <= lineOffsets.size()) {
+      return lineOffsets.get(line - 2);
+    }
+    return -1;
+  }
+
+  private CelSourceHelper() {}
+}

common/src/main/java/dev/cel/common/Source.java

@@ -0,0 +1,46 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package dev.cel.common;
+
+import dev.cel.common.annotations.Internal;
+import dev.cel.common.internal.CelCodePointArray;
+import java.util.Optional;
+
+/**
+ * Common interface definition for source properties.
+ *
+ * <p>CEL Library Internals. Do Not Use. Consumers should instead use the canonical implementations
+ * such as CelSource.
+ */
+@Internal
+public interface Source {
+
+  /** Gets the original textual content of this source, represented in an array of code points. */
+  CelCodePointArray getContent();
+
+  /**
+   * Gets the description of this source that may optionally be set (example: location of the file
+   * containing the source).
+   */
+  String getDescription();
+
+  /**
+   * Get the text from the source text that corresponds to {@code line}. Snippets are split based on
+   * the newline ('\n').
+   *
+   * @param line the line number starting from 1.
+   */
+  Optional<String> getSnippet(int line);
+}

common/src/main/java/dev/cel/common/internal/BasicCodePointArray.java

@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkPositionIndexes;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.Immutable;
 import dev.cel.common.annotations.Internal;
 
@@ -38,21 +39,23 @@ public final class BasicCodePointArray extends CelCodePointArray {
 
   private final int offset;
   private final int size;
+  private final ImmutableList<Integer> lineOffsets;
 
-  BasicCodePointArray(char[] codePoints, int size) {
-    this(codePoints, 0, size);
+  BasicCodePointArray(char[] codePoints, int size, ImmutableList<Integer> lineOffsets) {
+    this(codePoints, 0, lineOffsets, size);
   }
 
-  BasicCodePointArray(char[] codePoints, int offset, int size) {
+  BasicCodePointArray(char[] codePoints, int offset, ImmutableList<Integer> lineOffsets, int size) {
     this.codePoints = checkNotNull(codePoints);
     this.offset = offset;
     this.size = size;
+    this.lineOffsets = lineOffsets;
   }
 
   @Override
   public BasicCodePointArray slice(int i, int j) {
     checkPositionIndexes(i, j, size());
-    return new BasicCodePointArray(codePoints, offset + i, j - i);
+    return new BasicCodePointArray(codePoints, offset + i, lineOffsets, j - i);
   }
 
   @Override
@@ -66,6 +69,11 @@ public int size() {
     return size;
   }
 
+  @Override
+  public ImmutableList<Integer> lineOffsets() {
+    return lineOffsets;
+  }
+
   @Override
   public String toString() {
     return new String(codePoints, offset, size);