content: /*
   * MIT License
   *
   * Copyright (c) 2018 Alibaba Group
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  package com.tmall.wireless.tangram3.util;
  
  
  /**
   * Precondition class borrows from facebook, which originally is taken from guava
   */
  
  import android.os.Looper;
  import android.support.annotation.Nullable;
  
  import io.reactivex.Observer;
  
  /**
   * Static convenience methods that help a method or constructor check whether it was invoked
   * correctly (whether its <i>preconditions</i> have been met). These methods generally accept a
   * {@code boolean} expression which is expected to be {@code true} (or in the case of {@code
   * checkNotNull}, an object reference which is expected to be non-null). When {@code false} (or
   * {@code null}) is passed instead, the {@code Preconditions} method throws an unchecked exception,
   * which helps the calling method communicate to <i>its</i> caller that <i>that</i> caller has made
   * a mistake. Example: <pre>   {@code
   *
   *   /**
   *    * Returns the positive square root of the given value.
   *    *
   *    * @throws IllegalArgumentException if the value is negative
   *    *}{@code /
   *   public static double sqrt(double value) {
   *     Preconditions.checkArgument(value >= 0.0, "negative value: %s", value);
   *     // calculate the square root
   *   }
   *
   *   void exampleBadCaller() {
   *     double d = sqrt(-1.0);
   *   }}</pre>
   *
   * In this example, {@code checkArgument} throws an {@code IllegalArgumentException} to indicate
   * that {@code exampleBadCaller} made an error in <i>its</i> call to {@code sqrt}.
   *
   * <h3>Warning about performance</h3>
   *
   * <p>The goal of this class is to improve readability of code, but in some circumstances this may
   * come at a significant performance cost. Remember that parameter values for message construction
   * must all be computed eagerly, and autoboxing and varargs array creation may happen as well, even
   * when the precondition check then succeeds (as it should almost always do in production). In some
   * circumstances these wasted CPU cycles and allocations can add up to a real problem.
   * Performance-sensitive precondition checks can always be converted to the customary form:
   * <pre>   {@code
   *
   *   if (value < 0.0) {
   *     throw new IllegalArgumentException("negative value: " + value);
   *   }}</pre>
   *
   * <h3>Other types of preconditions</h3>
   *
   * <p>Not every type of precondition failure is supported by these methods. Continue to throw
   * standard JDK exceptions such as {@link java.util.NoSuchElementException} or {@link
   * UnsupportedOperationException} in the situations they are intended for.
   *
   * <h3>Non-preconditions</h3>
   *
   * <p>It is of course possible to use the methods of this class to check for invalid conditions
   * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
   * misleading to future readers of the code and of stack traces. See
   * <a href="http://code.google.com/p/guava-libraries/wiki/ConditionalFailuresExplained">Conditional
   * failures explained</a> in the Guava User Guide for more advice.
   *
   * <h3>{@code java.util.Objects.requireNonNull()}</h3>
   *
   * <p>Projects which use {@code com.google.common} should generally avoid the use of {@link
   * java.util.Objects#requireNonNull(Object)}. Instead, use whichever of {@link
   * #checkNotNull(Object)} or {@link Verify#verifyNotNull(Object)} is appropriate to the situation.
   * (The same goes for the message-accepting overloads.)
   *
   * <h3>Only {@code %s} is supported</h3>
   *
   * <p>In {@code Preconditions} error message template strings, only the {@code "%s"} specifier is
   * supported, not the full range of {@link java.util.Formatter} specifiers. However, note that if
   * the number of arguments does not match the number of occurrences of {@code "%s"} in the format
   * string, {@code Preconditions} will still behave as expected, and will still include all argument
   * values in the error message; the message will simply not be formatted exactly as intended.
   *
   * <h3>More information</h3>
   *
   * <p>See the Guava User Guide on
   * <a href="http://code.google.com/p/guava-libraries/wiki/PreconditionsExplained">using {@code
   * Preconditions}</a>.
   *
   * @author Kevin Bourrillion
   * @since 2.0 (imported from Google Collections Library)
   */
  public final class Preconditions {
      private Preconditions() {}
  
      /**
       * Ensures the truth of an expression involving one or more parameters to the calling method.
       *
       * @param expression a boolean expression
       * @throws IllegalArgumentException if {@code expression} is false
       */
      public static void checkArgument(boolean expression) {
          if (!expression) {
              throw new IllegalArgumentException();
          }
      }
  
      /**
       * Ensures the truth of an expression involving one or more parameters to the calling method.
       *
       * @param expression a boolean expression
       * @param errorMessage the exception message to use if the check fails; will be converted to a
       *     string using {@link String#valueOf(Object)}
       * @throws IllegalArgumentException if {@code expression} is false
       */
      public static void checkArgument(boolean expression, @Nullable Object errorMessage) {
          if (!expression) {
              throw new IllegalArgumentException(String.valueOf(errorMessage));
          }
      }
  
      /**
       * Ensures the truth of an expression involving one or more parameters to the calling method.
       *
       * @param expression a boolean expression
       * @param errorMessageTemplate a template for the exception message should the check fail. The
       *     message is formed by replacing each {@code %s} placeholder in the template with an
       *     argument. These are matched by position - the first {@code %s} gets {@code
       *     errorMessageArgs[0]}, etc.  Unmatched arguments will be appended to the formatted message
       *     in square braces. Unmatched placeholders will be left as-is.
       * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
       *     are converted to strings using {@link String#valueOf(Object)}.
       * @throws IllegalArgumentException if {@code expression} is false
       * @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or
       *     {@code errorMessageArgs} is null (don't let this happen)
       */
      public static void checkArgument(boolean expression,
                                       @Nullable String errorMessageTemplate,
                                       @Nullable Object... errorMessageArgs) {
          if (!expression) {
              throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
          }
      }
  
      /**
       * Ensures the truth of an expression involving the state of the calling instance, but not
       * involving any parameters to the calling method.
       *
       * @param expression a boolean expression
       * @throws IllegalStateException if {@code expression} is false
       */
      public static void checkState(boolean expression) {
          if (!expression) {
              throw new IllegalStateException();
          }
      }
  
      /**
       * Ensures the truth of an expression involving the state of the calling instance, but not
       * involving any parameters to the calling method.
       *
       * @param expression a boolean expression
       * @param errorMessage the exception message to use if the check fails; will be converted to a
       *     string using {@link String#valueOf(Object)}
       * @throws IllegalStateException if {@code expression} is false
       */
      public static void checkState(boolean expression, @Nullable Object errorMessage) {
          if (!expression) {
              throw new IllegalStateException(String.valueOf(errorMessage));
          }
      }
  
      /**
       * Ensures the truth of an expression involving the state of the calling instance, but not
       * involving any parameters to the calling method.
       *
       * @param expression a boolean expression
       * @param errorMessageTemplate a template for the exception message should the check fail. The
       *     message is formed by replacing each {@code %s} placeholder in the template with an
       *     argument. These are matched by position - the first {@code %s} gets {@code
       *     errorMessageArgs[0]}, etc.  Unmatched arguments will be appended to the formatted message
       *     in square braces. Unmatched placeholders will be left as-is.
       * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
       *     are converted to strings using {@link String#valueOf(Object)}.
       * @throws IllegalStateException if {@code expression} is false
       * @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or
       *     {@code errorMessageArgs} is null (don't let this happen)
       */
      public static void checkState(boolean expression,
                                    @Nullable String errorMessageTemplate,
                                    @Nullable Object... errorMessageArgs) {
          if (!expression) {
              throw new IllegalStateException(format(errorMessageTemplate, errorMessageArgs));
          }
      }
  
      /**
       * Ensures that an object reference passed as a parameter to the calling method is not null.
       *
       * @param reference an object reference
       * @return the non-null reference that was validated
       * @throws NullPointerException if {@code reference} is null
       */
      public static <T> T checkNotNull(T reference) {
          if (reference == null) {
              throw new NullPointerException();
          }
          return reference;
      }
  
      /**
       * Ensures that an object reference passed as a parameter to the calling method is not null.
       *
       * @param reference an object reference
       * @param errorMessage the exception message to use if the check fails; will be converted to a
       *     string using {@link String#valueOf(Object)}
       * @return the non-null reference that was validated
       * @throws NullPointerException if {@code reference} is null
       */
      public static <T> T checkNotNull(T reference, @Nullable Object errorMessage) {
          if (reference == null) {
              throw new NullPointerException(String.valueOf(errorMessage));
          }
          return reference;
      }
  
      /**
       * Ensures that an object reference passed as a parameter to the calling method is not null.
       *
       * @param reference an object reference
       * @param errorMessageTemplate a template for the exception message should the check fail. The
       *     message is formed by replacing each {@code %s} placeholder in the template with an
       *     argument. These are matched by position - the first {@code %s} gets {@code
       *     errorMessageArgs[0]}, etc.  Unmatched arguments will be appended to the formatted message
       *     in square braces. Unmatched placeholders will be left as-is.
       * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
       *     are converted to strings using {@link String#valueOf(Object)}.
       * @return the non-null reference that was validated
       * @throws NullPointerException if {@code reference} is null
       */
      public static <T> T checkNotNull(T reference,
                                       @Nullable String errorMessageTemplate,
                                       @Nullable Object... errorMessageArgs) {
          if (reference == null) {
              // If either of these parameters is null, the right thing happens anyway
              throw new NullPointerException(format(errorMessageTemplate, errorMessageArgs));
          }
          return reference;
      }
  
    /*
     * All recent hotspots (as of 2009) *really* like to have the natural code
     *
     * if (guardExpression) {
     *    throw new BadException(messageExpression);
     * }
     *
     * refactored so that messageExpression is moved to a separate String-returning method.
     *
     * if (guardExpression) {
     *    throw new BadException(badMsg(...));
     * }
     *
     * The alternative natural refactorings into void or Exception-returning methods are much slower.
     * This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%.  (This
     * is a hotspot optimizer bug, which should be fixed, but that's a separate, big project).
     *
     * The coding pattern above is heavily used in java.util, e.g. in ArrayList.  There is a
     * RangeCheckMicroBenchmark in the JDK that was used to test this.
     *
     * But the methods in this class want to throw different exceptions, depending on the args, so it
     * appears that this pattern is not directly applicable.  But we can use the ridiculous, devious
     * trick of throwing an exception in the middle of the construction of another exception.  Hotspot
     * is fine with that.
     */
  
      /**
       * Ensures that {@code index} specifies a valid <i>element</i> in an array, list or string of size
       * {@code size}. An element index may range from zero, inclusive, to {@code size}, exclusive.
       *
       * @param index a user-supplied index identifying an element of an array, list or string
       * @param size the size of that array, list or string
       * @return the value of {@code index}
       * @throws IndexOutOfBoundsException if {@code index} is negative or is not less than {@code size}
       * @throws IllegalArgumentException if {@code size} is negative
       */
      public static int checkElementIndex(int index, int size) {
          return checkElementIndex(index, size, "index");
      }
  
      /**
       * Ensures that {@code index} specifies a valid <i>element</i> in an array, list or string of size
       * {@code size}. An element index may range from zero, inclusive, to {@code size}, exclusive.
       *
       * @param index a user-supplied index identifying an element of an array, list or string
       * @param size the size of that array, list or string
       * @param desc the text to use to describe this index in an error message
       * @return the value of {@code index}
       * @throws IndexOutOfBoundsException if {@code index} is negative or is not less than {@code size}
       * @throws IllegalArgumentException if {@code size} is negative
       */
      public static int checkElementIndex(
              int index, int size, @Nullable String desc) {
          // Carefully optimized for execution by hotspot (explanatory comment above)
          if (index < 0 || index >= size) {
              throw new IndexOutOfBoundsException(badElementIndex(index, size, desc));
          }
          return index;
      }
  
      private static String badElementIndex(int index, int size, @Nullable String desc) {
          if (index < 0) {
              return format("%s (%s) must not be negative", desc, index);
          } else if (size < 0) {
              throw new IllegalArgumentException("negative size: " + size);
          } else { // index >= size
              return format("%s (%s) must be less than size (%s)", desc, index, size);
          }
      }
  
      /**
       * Ensures that {@code index} specifies a valid <i>position</i> in an array, list or string of
       * size {@code size}. A position index may range from zero to {@code size}, inclusive.
       *
       * @param index a user-supplied index identifying a position in an array, list or string
       * @param size the size of that array, list or string
       * @return the value of {@code index}
       * @throws IndexOutOfBoundsException if {@code index} is negative or is greater than {@code size}
       * @throws IllegalArgumentException if {@code size} is negative
       */
      public static int checkPositionIndex(int index, int size) {
          return checkPositionIndex(index, size, "index");
      }
  
      /**
       * Ensures that {@code index} specifies a valid <i>position</i> in an array, list or string of
       * size {@code size}. A position index may range from zero to {@code size}, inclusive.
       *
       * @param index a user-supplied index identifying a position in an array, list or string
       * @param size the size of that array, list or string
       * @param desc the text to use to describe this index in an error message
       * @return the value of {@code index}
       * @throws IndexOutOfBoundsException if {@code index} is negative or is greater than {@code size}
       * @throws IllegalArgumentException if {@code size} is negative
       */
      public static int checkPositionIndex(int index, int size, @Nullable String desc) {
          // Carefully optimized for execution by hotspot (explanatory comment above)
          if (index < 0 || index > size) {
              throw new IndexOutOfBoundsException(badPositionIndex(index, size, desc));
          }
          return index;
      }
  
      private static String badPositionIndex(int index, int size, @Nullable String desc) {
          if (index < 0) {
              return format("%s (%s) must not be negative", desc, index);
          } else if (size < 0) {
              throw new IllegalArgumentException("negative size: " + size);
          } else { // index > size
              return format("%s (%s) must not be greater than size (%s)", desc, index, size);
          }
      }
  
      /**
       * Ensures that {@code start} and {@code end} specify a valid <i>positions</i> in an array, list
       * or string of size {@code size}, and are in order. A position index may range from zero to
       * {@code size}, inclusive.
       *
       * @param start a user-supplied index identifying a starting position in an array, list or string
       * @param end a user-supplied index identifying a ending position in an array, list or string
       * @param size the size of that array, list or string
       * @throws IndexOutOfBoundsException if either index is negative or is greater than {@code size},
       *     or if {@code end} is less than {@code start}
       * @throws IllegalArgumentException if {@code size} is negative
       */
      public static void checkPositionIndexes(int start, int end, int size) {
          // Carefully optimized for execution by hotspot (explanatory comment above)
          if (start < 0 || end < start || end > size) {
              throw new IndexOutOfBoundsException(badPositionIndexes(start, end, size));
          }
      }
  
      private static String badPositionIndexes(int start, int end, int size) {
          if (start < 0 || start > size) {
              return badPositionIndex(start, size, "start index");
          }
          if (end < 0 || end > size) {
              return badPositionIndex(end, size, "end index");
          }
          // end < start
          return format("end index (%s) must not be less than start index (%s)", end, start);
      }
  
      /**
       * Substitutes each {@code %s} in {@code template} with an argument. These are matched by
       * position: the first {@code %s} gets {@code args[0]}, etc.  If there are more arguments than
       * placeholders, the unmatched arguments will be appended to the end of the formatted message in
       * square braces.
       *
       * @param template a non-null string containing 0 or more {@code %s} placeholders.
       * @param args the arguments to be substituted into the message template. Arguments are converted
       *     to strings using {@link String#valueOf(Object)}. Arguments can be null.
       */
      // Note that this is somewhat-improperly used from Verify.java as well.
      static String format(@Nullable String template, @Nullable Object... args) {
          template = String.valueOf(template); // null -> "null"
  
          // start substituting the arguments into the '%s' placeholders
          StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
          int templateStart = 0;
          int i = 0;
          while (i < args.length) {
              int placeholderStart = template.indexOf("%s", templateStart);
              if (placeholderStart == -1) {
                  break;
              }
              builder.append(template.substring(templateStart, placeholderStart));
              builder.append(args[i++]);
              templateStart = placeholderStart + 2;
          }
          builder.append(template.substring(templateStart));
  
          // if we run out of placeholders, append the extra args in square braces
          if (i < args.length) {
              builder.append(" [");
              builder.append(args[i++]);
              while (i < args.length) {
                  builder.append(", ");
                  builder.append(args[i++]);
              }
              builder.append(']');
          }
  
          return builder.toString();
      }
  
      public static boolean checkMainThread(Observer<?> observer) {
          if (Looper.myLooper() != Looper.getMainLooper()) {
              observer.onError(new IllegalStateException(
                  "Expected to be called on the main thread but was " + Thread.currentThread().getName()));
              return false;
          }
          return true;
      }
  }
  