Fix analysis server caching edge case http://code.google.com/p/dart/issues/detail?id=3423

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/CacheReader.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/CacheReader.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/CacheReader.java	(revision 0)
+++ editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/CacheReader.java	(revision 0)
@@ -0,0 +1,156 @@
+package com.google.dart.tools.core.analysis;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.LineNumberReader;
+import java.io.Reader;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Internal class for reading analysis state from disk when starting a new session.
+ */
+public class CacheReader {
+  static final String CACHE_VERSION_TAG = "v2";
+
+  private final LineNumberReader reader;
+
+  public CacheReader(Reader reader) throws IOException {
+    if (!reader.markSupported()) {
+      throw new IllegalArgumentException();
+    }
+    this.reader = reader instanceof LineNumberReader ? (LineNumberReader) reader
+        : new LineNumberReader(reader);
+    String line = this.reader.readLine();
+    if (!CACHE_VERSION_TAG.equals(line)) {
+      throw new IOException("Expected cache version " + CACHE_VERSION_TAG + " but found " + line);
+    }
+  }
+
+  /**
+   * Read a boolean originally written by {@link CacheWriter#writeBoolean(boolean)}
+   */
+  public boolean readBoolean() throws IOException {
+    String line = reader.readLine();
+    if ("true".equals(line)) {
+      return true;
+    }
+    if ("false".equals(line)) {
+      return false;
+    }
+    throw new IOException("Expected true or false, but found " + line);
+  }
+
+  /**
+   * Read a collection of file paths originally written by {@link
+   * CacheWriter#writeFilePaths(Collection<File>, String)}
+   * 
+   * @param files the collection into which files are placed (not <code>null</code> )
+   * @param endTag the tag used to denote the end of the collection of file paths
+   */
+  public void readFilePaths(Collection<File> files, String endTag) throws IOException {
+    while (true) {
+      String path = readString();
+      if (path == null) {
+        throw new IOException("Expected " + endTag + " but found EOF");
+      }
+      if (path.equals(endTag)) {
+        break;
+      }
+      files.add(new File(path));
+    }
+  }
+
+  /**
+   * Read a string originally written by {@link CacheWriter#writeString(String)}
+   * 
+   * @return the string or <code>null</code> if EOF
+   */
+  public String readString() throws IOException {
+
+    // Normal case... read a line
+
+    reader.mark(1);
+    int ch = reader.read();
+    if (ch == -1) {
+      throw new IOException("Unexpected EOF when reading string");
+    }
+    if (ch != '!') {
+      reader.reset();
+      return reader.readLine();
+    }
+
+    // If the string contains a line separator, then string length is encoded
+    // preceding the string as bang-number-bang
+
+    int length = 0;
+    while (true) {
+      ch = reader.read();
+      if (ch == '!') {
+        break;
+      }
+      if (ch < '0' || ch > '9') {
+        throw new IOException("Expected digit, but found character value " + ch);
+      }
+      length = length * 10 + ch - '0';
+    }
+    char[] buf = new char[length];
+    int count = reader.read(buf);
+    if (length != count) {
+      throw new IOException("Expected " + length + " characters, but found only " + count);
+    }
+    reader.readLine();
+    return new String(buf);
+  }
+
+  /**
+   * Read a collection of key/value pairs originally written by
+   * {@link CacheWriter#writeStringFileMap(Map, String)} where the keys are strings and the values
+   * are instances of {@link java.io.File}.
+   * 
+   * @param endTag the tag used to denote the end of the collection
+   * @return the collection (not <code>null</code>)
+   */
+  public HashMap<String, File> readStringFileMap(String endTag) throws IOException {
+    HashMap<String, File> result = new HashMap<String, File>();
+    while (true) {
+      String key = readString();
+      if (key == null) {
+        throw new IOException("Expected " + endTag + " but found EOF");
+      }
+      if (key.equals(endTag)) {
+        break;
+      }
+      String absFilePath = readString();
+      if (absFilePath == null) {
+        throw new IOException("Expected absolute file path but found EOF");
+      }
+      result.put(key, new File(absFilePath));
+    }
+    return result;
+  }
+
+  /**
+   * Read a collection of strings originally written by
+   * {@link CacheWriter#writeStringSet(Set, String)}.
+   * 
+   * @param endTag the tag used to denote the end of the collection of strings
+   * @return the collection of strings (not <code>null</code>)
+   */
+  public HashSet<String> readStringSet(String endTag) throws IOException {
+    HashSet<String> result = new HashSet<String>();
+    while (true) {
+      String string = readString();
+      if (string == null) {
+        throw new IOException("Expected " + endTag + " but found EOF");
+      }
+      if (string.equals(endTag)) {
+        return result;
+      }
+      result.add(string);
+    }
+  }
+}