ahat - An android heap dump viewer. Initial checkin.

ahat is an android-aware heap dump viewer based on perflib with a
simple html interface.

Change-Id: I7c18a7603dbbe735f778a95cd047f4f9ec1705ef
diff --git a/tools/ahat/src/Query.java b/tools/ahat/src/Query.java
new file mode 100644
index 0000000..f910608
--- /dev/null
+++ b/tools/ahat/src/Query.java
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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.android.ahat;
+
+import java.net.URI;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * A class for getting and modifying query parameters.
+ */
+class Query {
+  private URI mUri;
+
+  // Map from parameter name to value. If the same parameter appears multiple
+  // times, only the last value is used.
+  private Map<String, String> mParams;
+
+  public Query(URI uri) {
+    mUri = uri;
+    mParams = new HashMap<String, String>();
+
+    String query = uri.getQuery();
+    if (query != null) {
+      for (String param : query.split("&")) {
+        int i = param.indexOf('=');
+        if (i < 0) {
+          mParams.put(param, "");
+        } else {
+          mParams.put(param.substring(0, i), param.substring(i + 1));
+        }
+      }
+    }
+  }
+
+  /**
+   * Return the value of a query parameter with the given name.
+   * If there is no query parameter with that name, returns the default value.
+   * If there are multiple query parameters with that name, the value of the
+   * last query parameter is returned.
+   * If the parameter is defined with an empty value, "" is returned.
+   */
+  public String get(String name, String defaultValue) {
+    String value = mParams.get(name);
+    return (value == null) ? defaultValue : value;
+  }
+
+  /**
+   * Return the long value of a query parameter with the given name.
+   */
+  public long getLong(String name, long defaultValue) {
+    String value = get(name, null);
+    return value == null ? defaultValue : Long.parseLong(value);
+  }
+
+  /**
+   * Return the int value of a query parameter with the given name.
+   */
+  public int getInt(String name, int defaultValue) {
+    String value = get(name, null);
+    return value == null ? defaultValue : Integer.parseInt(value);
+  }
+
+  /**
+   * Return a uri suitable for an href target that links to the current
+   * page, except with the named query parameter set to the new value.
+   *
+   * The generated parameters will be sorted alphabetically so it is easier to
+   * test.
+   */
+  public URI with(String name, String value) {
+    StringBuilder newQuery = new StringBuilder();
+    newQuery.append(mUri.getRawPath());
+    newQuery.append('?');
+
+    Map<String, String> params = new TreeMap<String, String>(mParams);
+    params.put(name, value);
+    String and = "";
+    for (Map.Entry<String, String> entry : params.entrySet()) {
+      newQuery.append(and);
+      newQuery.append(entry.getKey());
+      newQuery.append('=');
+      newQuery.append(entry.getValue());
+      and = "&";
+    }
+    return DocString.uri(newQuery.toString());
+  }
+
+  /**
+   * Return a uri suitable for an href target that links to the current
+   * page, except with the named query parameter set to the new long value.
+   */
+  public URI with(String name, long value) {
+    return with(name, String.valueOf(value));
+  }
+}