Merge pull request #15 from gharris1727/iterator-initializer

CC-7198: Add iterator initializer schema field

Author: C0urante

README.md

@@ -76,17 +76,19 @@ read from the file after decoding with the specified format (currently
 "json" and "binary" are the only supported values, and "binary" may be
 somewhat buggy).
 + __iteration:__ A JSON object that conforms to the following format:
-`{"start": <start>, "restart": <restart>, "step": <step>}` ("start" has
-to be specified, but "restart" and "step" do not). If provided with a
+`{"start": <start>, "restart": <restart>, "step": <step>, "initial": 
+<initial> }` ("start" has to be specified, but "restart", "step", 
+and "initial" do not). If provided with a
 numeric schema, ensures that the first generated value will be equal to
-&lt;start&gt;, and successive values will increase by &lt;step&gt;,
-wrapping around at &lt;restart&gt;; &lt;step&gt; will default to 1 if
-&lt;restart&gt; is greater than &lt;step&gt;, will default to -1 if
-&lt;restart&gt; is less than &lt;step&gt;, and an error will be thrown
-if &lt;restart&gt; is equal to &lt;step&gt;. If provided with a boolean
+&lt;initial&gt; (or &lt;start&gt; if &lt;initial&gt; is not specified),
+and successive values will increase by &lt;step&gt;, wrapping around at 
+&lt;restart&gt; back to &lt;start&gt;; &lt;step&gt; will default to 1 if
+&lt;restart&gt; is greater than &lt;start&gt;, will default to -1 if
+&lt;restart&gt; is less than &lt;start&gt;, and an error will be thrown
+if &lt;restart&gt; is equal to &lt;start&gt;. If provided with a boolean
 schema, only &lt;start&gt; may be specified; the resulting values will
 begin with &lt;start&gt; and alternate from `true` to `false` and from
-`false` to `true` from that point on.
+`false` to `true` from that point on. 
 + __range:__ A JSON object that conforms to the following format:
 `{"min": <min>, "max": <max>}` (at least one of "min" or "max" must be
 specified). If provided, ensures that the generated number will be

src/main/java/io/confluent/avro/random/generator/Generator.java

@@ -189,6 +189,12 @@ public class Generator {
    * {@link #ITERATION_PROP_RESTART} is less than the value for {@link #ITERATION_PROP_START}.
    */
   public static final String ITERATION_PROP_STEP = "step";
+  /**
+   * The name of the attribute for specifying the initial value in a schema with iterative
+   * generation. If given, must be a numeric type that is integral if the given schema is as well.
+   * If not given, defaults to the value for {@link #ITERATION_PROP_START}.
+   */
+  public static final String ITERATION_PROP_INITIAL = "initial";
 
   static final String DECIMAL_LOGICAL_TYPE_NAME = "decimal";
 
@@ -650,6 +656,7 @@ private Iterator<Object> getIntegralIterator(
       Long iterationStartField,
       Long iterationRestartField,
       Long iterationStepField,
+      Long iterationInitialField,
       IntegralIterator.Type type) {
 
     if (iterationStartField == null) {
@@ -750,10 +757,16 @@ private Iterator<Object> getIntegralIterator(
       }
     }
 
+    long iterationInitial = iterationStart;
+    if (iterationInitialField != null) {
+      iterationInitial = iterationInitialField;
+    }
+
     return new IntegralIterator(
         iterationStart,
         iterationRestart,
         iterationStep,
+        iterationInitial,
         generation,
         type
     );
@@ -763,6 +776,7 @@ private Iterator<Object> getDecimalIterator(
       Double iterationStartField,
       Double iterationRestartField,
       Double iterationStepField,
+      Double iterationInitialField,
       DecimalIterator.Type type) {
 
     if (iterationStartField == null) {
@@ -863,10 +877,16 @@ private Iterator<Object> getDecimalIterator(
       }
     }
 
+    double iterationInitial = iterationStart;
+    if (iterationInitialField != null) {
+      iterationInitial = iterationInitialField;
+    }
+
     return new DecimalIterator(
         iterationStart,
         iterationRestart,
         iterationStep,
+        iterationInitial,
         generation,
         type
     );
@@ -927,10 +947,16 @@ private Iterator<Object> getDoubleIterator(final Map iterationProps) {
         ITERATION_PROP_STEP,
         iterationProps
     );
+    Double iterationInitialField = getDecimalNumberField(
+        ITERATION_PROP,
+        ITERATION_PROP_INITIAL,
+        iterationProps
+    );
     return getDecimalIterator(
         iterationStartField,
         iterationRestartField,
         iterationStepField,
+        iterationInitialField,
         DecimalIterator.Type.DOUBLE
     );
   }
@@ -951,10 +977,16 @@ private Iterator<Object> getFloatIterator(final Map iterationProps) {
         ITERATION_PROP_STEP,
         iterationProps
     );
+    Float iterationInitialField = getFloatNumberField(
+        ITERATION_PROP,
+        ITERATION_PROP_INITIAL,
+        iterationProps
+    );
     return getDecimalIterator(
         iterationStartField != null ? iterationStartField.doubleValue() : null,
         iterationRestartField != null ? iterationRestartField.doubleValue() : null,
         iterationStepField != null ? iterationStepField.doubleValue() : null,
+        iterationInitialField != null ? iterationInitialField.doubleValue() : null,
         DecimalIterator.Type.FLOAT
     );
   }
@@ -975,10 +1007,16 @@ private Iterator<Object> getLongIterator(final Map iterationProps) {
         ITERATION_PROP_STEP,
         iterationProps
     );
+    Long iterationInitialField = getIntegralNumberField(
+        ITERATION_PROP,
+        ITERATION_PROP_INITIAL,
+        iterationProps
+    );
     return getIntegralIterator(
         iterationStartField,
         iterationRestartField,
         iterationStepField,
+        iterationInitialField,
         IntegralIterator.Type.LONG
     );
   }
@@ -1013,10 +1051,16 @@ private Iterator<Object> getIntegerIterator(Map iterationProps) {
         ITERATION_PROP_STEP,
         iterationProps
     );
+    Integer iterationInitialField = getIntegerNumberField(
+        ITERATION_PROP,
+        ITERATION_PROP_INITIAL,
+        iterationProps
+    );
     return getIntegralIterator(
         iterationStartField != null ? iterationStartField.longValue() : null,
         iterationRestartField != null ? iterationRestartField.longValue() : null,
         iterationStepField != null ? iterationStepField.longValue() : null,
+        iterationInitialField != null ? iterationInitialField.longValue() : null,
         IntegralIterator.Type.INTEGER
     );
   }
@@ -1486,18 +1530,19 @@ public enum Type {
     private final Type type;
     private BigInteger current;
 
-    public IntegralIterator(long start, long restart, long step, long count, Type type) {
+    public IntegralIterator(long start, long restart, long step, long initial, long count, Type type) {
       this.start = BigInteger.valueOf(start);
       this.restart = BigInteger.valueOf(restart);
       this.step = BigInteger.valueOf(step);
       this.type = type;
-      current = BigInteger.ZERO;
+      current = BigInteger.valueOf(initial).subtract(this.start);
       if (count > 0) {
         // This is essentially the following expression when ignoring negative values:
         // current = (count * step) % (restart - start)
         // except BigInteger::mod only operates on positive numbers, so remove and re-add the sign after the modulo.
         current = BigInteger.valueOf(count)
             .multiply(this.step)
+            .add(current)
             .abs()
             .mod(this.restart.subtract(this.start).abs())
             .multiply(this.step.divide(this.step.abs()));
@@ -1541,16 +1586,17 @@ public enum Type {
     private final Type type;
     private BigDecimal current;
 
-    public DecimalIterator(double start, double restart, double step, long count, Type type) {
+    public DecimalIterator(double start, double restart, double step, double initial, long count, Type type) {
       this.start = BigDecimal.valueOf(start);
       this.restart = BigDecimal.valueOf(restart);
       this.modulo = this.restart.subtract(this.start);
       this.step = BigDecimal.valueOf(step);
       this.type = type;
-      current = BigDecimal.ZERO;
+      current = BigDecimal.valueOf(initial).subtract(this.start);
       if (count > 0) {
         current = BigDecimal.valueOf(count)
             .multiply(this.step)
+            .add(current)
             .remainder(this.modulo);
       }
     }

src/test/java/io/confluent/avro/random/generator/IterationTest.java

@@ -35,6 +35,15 @@ public void shouldCreateIteratorPerFieldEvenIfSameSchema() {
     assertThat(((GenericRecord) second.get("nested")).get("long_iteration"), is(-3L));
   }
 
+  @Test
+  public void shouldBeginIterationAtInitialValue() {
+    final GenericRecord generated = (GenericRecord) generator.generate();
+    assertThat(generated.get("int_iteration_offset"), is(40));
+    assertThat(generated.get("long_iteration_offset"), is(0L));
+    assertThat(generated.get("float_iteration_offset"), is(0.0f));
+    assertThat(generated.get("double_iteration_offset"), is(5.0));
+  }
+
   @Test
   public void shouldSupportStringIteration() {
     final GenericRecord first = (GenericRecord) generator.generate();

src/test/resources/test-schemas/iteration.json

@@ -26,6 +26,19 @@
           }
         }
       },
+      {
+        "name": "int_iteration_offset",
+        "type": {
+          "type": "int",
+          "arg.properties": {
+            "iteration": {
+              "start": 50,
+              "restart": -10,
+              "initial": 40
+            }
+          }
+        }
+      },
       {
         "name": "long_iteration",
         "type": {
@@ -39,6 +52,20 @@
           }
         }
       },
+      {
+        "name": "long_iteration_offset",
+        "type": {
+          "type": "long",
+          "arg.properties": {
+            "iteration": {
+              "start": -50,
+              "restart": 100,
+              "step": 47,
+              "initial": 0
+            }
+          }
+        }
+      },
       {
         "name": "float_iteration",
         "type": {
@@ -51,6 +78,19 @@
           }
         }
       },
+      {
+        "name": "float_iteration_offset",
+        "type": {
+          "type":"float",
+          "arg.properties": {
+            "iteration": {
+              "start": 10.4,
+              "step": 5.1,
+              "initial": 0
+            }
+          }
+        }
+      },
       {
         "name": "double_iteration",
         "type": {
@@ -64,6 +104,20 @@
           }
         }
       },
+      {
+        "name": "double_iteration_offset",
+        "type": {
+          "type": "double",
+          "arg.properties": {
+            "iteration": {
+              "start": 0.0,
+              "restart": 10.0,
+              "step": 27.3,
+              "initial": 5.0
+            }
+          }
+        }
+      },
       {
         "name": "string_iteration",
         "type": {