1 files changed, 112 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/ParserInputSource.java b/src/main/java/com/google/devtools/build/lib/syntax/ParserInputSource.java
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+++ b/src/main/java/com/google/devtools/build/lib/syntax/ParserInputSource.java
@@ -0,0 +1,112 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// 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
+//
+//    http://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 com.google.devtools.build.lib.syntax;
+
+import com.google.common.hash.HashCode;
+import com.google.devtools.build.lib.vfs.FileSystemUtils;
+import com.google.devtools.build.lib.vfs.Path;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * An abstraction for reading input from a file or taking it as a pre-cooked
+ * char[] or String.
+ */
+public abstract class ParserInputSource {
+
+  protected ParserInputSource() {}
+
+  /**
+   * Returns the content of the input source.
+   */
+  public abstract char [] getContent();
+
+  /**
+   * Returns the path of the input source. Note: Once constructed, this object
+   * will never re-read the content from path.
+   */
+  public abstract Path getPath();
+
+  /**
+   * Create an input source instance by (eagerly) reading from the file at
+   * path. The file is assumed to be ISO-8859-1 encoded and smaller than
+   * 2 Gigs - these assumptions are reasonable for BUILD files, which is
+   * all we care about here.
+   */
+  public static ParserInputSource create(Path path) throws IOException {
+    char[] content = FileSystemUtils.readContentAsLatin1(path);
+    if (path.getFileSize() > content.length) {
+      // This assertion is to help diagnose problems arising from the
+      // filesystem;  see bugs and #859334 and #920195.
+      throw new IOException("Unexpected short read from file '" + path
+          + "' (expected " + path.getFileSize() + ", got " + content.length + " bytes)");
+    }
+    return create(content, path);
+  }
+
+  /**
+   * Create an input source from the given content, and associate path with
+   * this source.  Path will be used in error messages etc. but we will *never*
+   * attempt to read the content from path.
+   */
+  public static ParserInputSource create(String content, Path path) {
+    return create(content.toCharArray(), path);
+  }
+
+  /**
+   * Create an input source from the given content, and associate path with
+   * this source.  Path will be used in error messages etc. but we will *never*
+   * attempt to read the content from path.
+   */
+  public static ParserInputSource create(final char[] content, final Path path) {
+    return new ParserInputSource() {
+
+      @Override
+      public char[] getContent() {
+        return content;
+      }
+
+      @Override
+      public Path getPath() {
+        return path;
+      }
+    };
+  }
+
+  /**
+   * Create an input source from the given input stream, and associate path
+   * with this source.  'path' will be used in error messages, etc, but will
+   * not (in general) be used to to read the content from path.
+   *
+   * (The exception is the case in which Python pre-processing is required; the
+   * path will be used to provide the input to the Python pre-processor.
+   * Arguably, we should just send the content as input to the subprocess
+   * instead of using the path, but it's not clear it's worth the effort.)
+   */
+  public static ParserInputSource create(InputStream in, Path path) throws IOException {
+    try {
+      return create(new String(FileSystemUtils.readContentAsLatin1(in)), path);
+    } finally {
+      in.close();
+    }
+  }
+
+  /**
+   * Returns a hash code calculated from the string content of this file.
+   */
+  public String contentHashCode() throws IOException {
+    return HashCode.fromBytes(getPath().getMD5Digest()).toString();
+  }
+}