Merge pull request #1529 from finos/1187-random-strings-uniformly-dis…

…tribute

fix(#1187): String lengths are uniformly random

common/src/main/java/com/scottlogic/deg/common/util/Defaults.java

@@ -32,6 +32,7 @@ public class Defaults {
 
     public static final BigDecimal NUMERIC_MAX = new BigDecimal("1e20");
     public static final BigDecimal NUMERIC_MIN = new BigDecimal("-1e20");
+
     public static final int MAX_STRING_LENGTH = 1000;
     public static final OffsetDateTime ISO_MAX_DATE = OffsetDateTime.of(9999, 12, 31, 23, 59, 59, 999_000_000, ZoneOffset.UTC);
     public static final OffsetDateTime ISO_MIN_DATE = OffsetDateTime.of(1, 1, 1, 0, 0, 0, 0, ZoneOffset.UTC);

generator/src/main/java/com/scottlogic/deg/generator/generation/string/factorys/RandomStringFactory.java

@@ -16,62 +16,46 @@
 
 package com.scottlogic.deg.generator.generation.string.factorys;
 
+import com.scottlogic.deg.common.ValidationException;
 import com.scottlogic.deg.generator.generation.string.StringUtils;
 import com.scottlogic.deg.generator.utils.RandomNumberGenerator;
 import dk.brics.automaton.State;
 import dk.brics.automaton.Transition;
 
+import java.util.LinkedList;
 import java.util.List;
 
 public class RandomStringFactory {
 
-    public String createRandomString(
-            String currentString,
-            State state,
-            int minLength,
-            int maxLength,
-            RandomNumberGenerator random) {
+    public String createRandomString(State state, RandomNumberGenerator random) {
+        List<Integer> validIndices = new LinkedList<>();
 
-        if (finishCreating(currentString, state, minLength, maxLength, random)) {
-            return currentString;
-        }
-
-        List<Transition> transitions = state.getSortedTransitions(false);
-
-        Transition randomTransition = transitions.get(random.nextInt(transitions.size()));
-
-        char randomChar = getRandomChar(random, randomTransition);
-
-        return createRandomString(
-            currentString + randomChar,
-            randomTransition.getDest(),
-            minLength,
-            maxLength,
-            random);
-    }
-
-    private boolean finishCreating(
-            String currentString,
-            State state,
-            int minLength,
-            int maxLength,
-            RandomNumberGenerator random) {
+        StringBuilder builder = new StringBuilder();
 
         if (state.isAccept()) {
-            if (currentString.length() == maxLength) {
-                return true;
-            }
-            if (currentString.length() >= minLength && randomlyStop(random)) {
-                return true;
+            validIndices.add(0);
+        }
+
+        for (int i = 1; !finishCreating(state); i++) {
+            List<Transition> transitions = state.getSortedTransitions(false);
+            Transition randomTransition = transitions.get(random.nextInt(transitions.size()));
+            builder.append(getRandomChar(random, randomTransition));
+            state = randomTransition.getDest();
+            if (state.isAccept()) {
+                validIndices.add(i);
             }
         }
 
-        return state.getTransitions().isEmpty();
-    }
+        if (validIndices.isEmpty()) {
+            throw new ValidationException("No possible states from the current regex");
+        }
 
+        int randomIndex = random.nextInt(validIndices.size());
+        return builder.toString().substring(0, validIndices.get(randomIndex));
+    }
 
-    private boolean randomlyStop(RandomNumberGenerator random) {
-        return random.nextInt(10) < 3; // 3 in 10 chance of stopping
+    private boolean finishCreating(State state) {
+        return state.getTransitions().isEmpty();
     }
 
     /**

generator/src/main/java/com/scottlogic/deg/generator/generation/string/generators/RegexStringGenerator.java

@@ -16,10 +16,13 @@
 
 package com.scottlogic.deg.generator.generation.string.generators;
 
+import com.scottlogic.deg.common.profile.FieldType;
+import com.scottlogic.deg.generator.fieldspecs.FieldSpecFactory;
 import com.scottlogic.deg.generator.generation.string.AutomatonUtils;
 import com.scottlogic.deg.generator.generation.string.iterators.FiniteStringAutomatonIterator;
 import com.scottlogic.deg.generator.generation.string.factorys.InterestingStringFactory;
 import com.scottlogic.deg.generator.generation.string.factorys.RandomStringFactory;
+import com.scottlogic.deg.generator.restrictions.string.StringRestrictions;
 import com.scottlogic.deg.generator.utils.RandomNumberGenerator;
 import dk.brics.automaton.Automaton;
 
@@ -39,6 +42,8 @@ public class RegexStringGenerator implements StringGenerator {
      */
     private static final Map<String, Automaton> containingRegexAutomatonCache = new HashMap<>();
 
+    private static final RegexStringGenerator DEFAULT = (RegexStringGenerator) ((StringRestrictions) FieldSpecFactory.fromType(FieldType.STRING).getRestrictions()).createGenerator();
+
     private Automaton automaton;
     private final String regexRepresentation;
 
@@ -119,7 +124,7 @@ RegexStringGenerator union(RegexStringGenerator otherGenerator) {
     @Override
     public StringGenerator complement() {
         return new RegexStringGenerator(
-            this.automaton.clone().complement(),
+            this.automaton.clone().complement().intersection(DEFAULT.automaton),
             complementaryRepresentation(this.regexRepresentation));
     }
 
@@ -150,10 +155,7 @@ public Stream<String> generateAllValues() {
     public Stream<String> generateRandomValues(RandomNumberGenerator randomNumberGenerator) {
         return Stream.generate(
             () -> randomStringFactory.createRandomString(
-                "",
                 automaton.getInitialState(),
-                1,
-                Integer.MAX_VALUE,
                 randomNumberGenerator));
     }
 

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/AfterConstantTimeConstraint.java

@@ -22,7 +22,7 @@
 import com.scottlogic.deg.generator.restrictions.linear.Limit;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictions;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory;
-import com.scottlogic.deg.generator.utils.Defaults;
+import com.scottlogic.deg.generator.utils.GeneratorDefaults;
 
 import java.time.LocalTime;
 
@@ -50,7 +50,7 @@ public AtomicConstraint negate() {
     public FieldSpec toFieldSpec() {
         final Limit<LocalTime> min = new Limit<>(referenceValue.getValue(), false);
         final LinearRestrictions<LocalTime> timeRestrictions =
-            LinearRestrictionsFactory.createTimeRestrictions(min, Defaults.TIME_MAX_LIMIT);
+            LinearRestrictionsFactory.createTimeRestrictions(min, GeneratorDefaults.TIME_MAX_LIMIT);
         return FieldSpecFactory.fromRestriction(timeRestrictions);
     }
 }

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/AfterConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createDateTimeRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MAX_LIMIT;
 
 public class AfterConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/AfterOrAtConstraint.java

@@ -27,7 +27,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createDateTimeRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MAX_LIMIT;
 
 public class AfterOrAtConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/AfterOrEqualToConstantTimeConstraint.java

@@ -22,7 +22,7 @@
 import com.scottlogic.deg.generator.restrictions.linear.Limit;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictions;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory;
-import com.scottlogic.deg.generator.utils.Defaults;
+import com.scottlogic.deg.generator.utils.GeneratorDefaults;
 
 import java.time.LocalTime;
 
@@ -50,7 +50,7 @@ public AtomicConstraint negate() {
     public FieldSpec toFieldSpec() {
         final Limit<LocalTime> min = new Limit<>(referenceValue.getValue(), true);
         final LinearRestrictions<LocalTime> timeRestrictions =
-            LinearRestrictionsFactory.createTimeRestrictions(min, Defaults.TIME_MAX_LIMIT);
+            LinearRestrictionsFactory.createTimeRestrictions(min, GeneratorDefaults.TIME_MAX_LIMIT);
         return FieldSpecFactory.fromRestriction(timeRestrictions);
     }
 }

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/BeforeConstantTimeConstraint.java

@@ -22,7 +22,7 @@
 import com.scottlogic.deg.generator.restrictions.linear.Limit;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictions;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory;
-import com.scottlogic.deg.generator.utils.Defaults;
+import com.scottlogic.deg.generator.utils.GeneratorDefaults;
 
 import java.time.LocalTime;
 
@@ -51,7 +51,7 @@ public FieldSpec toFieldSpec() {
 
         final Limit<LocalTime> max = new Limit<>(referenceValue.getValue(), false);
         final LinearRestrictions<LocalTime> timeRestriction =
-            LinearRestrictionsFactory.createTimeRestrictions(Defaults.TIME_MIN_LIMIT, max);
+            LinearRestrictionsFactory.createTimeRestrictions(GeneratorDefaults.TIME_MIN_LIMIT, max);
         if (timeRestriction.isContradictory()) {
             return FieldSpecFactory.nullOnly();
         }

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/BeforeConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createDateTimeRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MIN_LIMIT;
 
 public class BeforeConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/BeforeOrAtConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createDateTimeRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MIN_LIMIT;
 
 public class BeforeOrAtConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/BeforeOrEqualToConstantTimeConstraint.java

@@ -22,7 +22,7 @@
 import com.scottlogic.deg.generator.restrictions.linear.Limit;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictions;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory;
-import com.scottlogic.deg.generator.utils.Defaults;
+import com.scottlogic.deg.generator.utils.GeneratorDefaults;
 
 import java.time.LocalTime;
 
@@ -49,7 +49,7 @@ public AtomicConstraint negate() {
     public FieldSpec toFieldSpec() {
         final Limit<LocalTime> max = new Limit<>(referenceValue.getValue(), true);
         final LinearRestrictions<LocalTime> timeRestriction =
-            LinearRestrictionsFactory.createTimeRestrictions(Defaults.TIME_MIN_LIMIT, max);
+            LinearRestrictionsFactory.createTimeRestrictions(GeneratorDefaults.TIME_MIN_LIMIT, max);
         return FieldSpecFactory.fromRestriction(timeRestriction);
     }
 }

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/GranularToDateConstraint.java

@@ -25,8 +25,8 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createDateTimeRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MAX_LIMIT;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MIN_LIMIT;
 
 public class GranularToDateConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/GranularToTimeConstraint.java

@@ -21,7 +21,7 @@
 import com.scottlogic.deg.generator.fieldspecs.FieldSpec;
 import com.scottlogic.deg.generator.fieldspecs.FieldSpecFactory;
 import com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory;
-import com.scottlogic.deg.generator.utils.Defaults;
+import com.scottlogic.deg.generator.utils.GeneratorDefaults;
 
 public class GranularToTimeConstraint implements AtomicConstraint {
     public final TimeGranularity timeGranularity;
@@ -51,8 +51,8 @@ public AtomicConstraint negate() {
     public FieldSpec toFieldSpec() {
         return FieldSpecFactory.fromRestriction(
             LinearRestrictionsFactory.createTimeRestrictions(
-                Defaults.TIME_MIN_LIMIT,
-                Defaults.TIME_MAX_LIMIT,
+                GeneratorDefaults.TIME_MIN_LIMIT,
+                GeneratorDefaults.TIME_MAX_LIMIT,
                 timeGranularity));
     }
 }

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/GreaterThanConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MAX_LIMIT;
 
 public class GreaterThanConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/GreaterThanOrEqualToConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MAX_LIMIT;
 
 public class GreaterThanOrEqualToConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/LessThanConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MIN_LIMIT;
 
 public class LessThanConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/profile/constraints/atomic/LessThanOrEqualToConstraint.java

@@ -26,7 +26,7 @@
 import java.util.Objects;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MIN_LIMIT;
 
 public class LessThanOrEqualToConstraint implements AtomicConstraint {
     public final Field field;

generator/src/main/java/com/scottlogic/deg/generator/restrictions/linear/LinearRestrictionsFactory.java

@@ -22,7 +22,7 @@
 import java.time.OffsetDateTime;
 
 import static com.scottlogic.deg.common.util.Defaults.*;
-import static com.scottlogic.deg.generator.utils.Defaults.*;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.*;
 
 public class LinearRestrictionsFactory {
 

generator/src/main/java/com/scottlogic/deg/generator/utils/Defaults.java → generator/src/main/java/com/scottlogic/deg/generator/utils/GeneratorDefaults.java

@@ -24,7 +24,7 @@
 
 import static com.scottlogic.deg.common.util.Defaults.*;
 
-public class Defaults {
+public class GeneratorDefaults {
 
     public static final Limit<BigDecimal> NUMERIC_MAX_LIMIT = new Limit<>(NUMERIC_MAX, true);
     public static final Limit<BigDecimal> NUMERIC_MIN_LIMIT= new Limit<>(NUMERIC_MIN, true);

generator/src/test/java/com/scottlogic/deg/generator/fieldspecs/FieldSpecTests.java

@@ -33,7 +33,7 @@
 
 import static com.scottlogic.deg.common.profile.FieldType.*;
 import static com.scottlogic.deg.generator.restrictions.string.StringRestrictionsFactory.forMaxLength;
-import static com.scottlogic.deg.generator.utils.Defaults.*;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.*;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.hamcrest.core.IsNot.not;
 import static org.junit.Assert.assertFalse;

generator/src/test/java/com/scottlogic/deg/generator/fieldspecs/RestrictionsMergeOperationTest.java

@@ -33,9 +33,9 @@
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createDateTimeRestrictions;
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MAX_LIMIT;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MAX_LIMIT;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MIN_LIMIT;
 import static org.mockito.Mockito.*;
 
 class RestrictionsMergeOperationTest {

generator/src/test/java/com/scottlogic/deg/generator/generation/FieldSpecGetFieldValueSourceTests.java

@@ -37,8 +37,8 @@
 
 import static com.scottlogic.deg.common.profile.FieldType.*;
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MAX_LIMIT;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MIN_LIMIT;
 
 public class FieldSpecGetFieldValueSourceTests {
 

generator/src/test/java/com/scottlogic/deg/generator/generation/fieldvaluesources/RealNumberFieldValueSourceTests.java

@@ -35,8 +35,8 @@
 import java.util.stream.Stream;
 
 import static com.scottlogic.deg.generator.restrictions.linear.LinearRestrictionsFactory.createNumericRestrictions;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MAX_LIMIT;
-import static com.scottlogic.deg.generator.utils.Defaults.NUMERIC_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.NUMERIC_MIN_LIMIT;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.Matchers.*;
 

generator/src/test/java/com/scottlogic/deg/generator/generation/fieldvaluesources/datetime/DateTimeFieldValueSourceTests.java

@@ -34,8 +34,8 @@
 
 import static com.scottlogic.deg.common.util.Defaults.ISO_MAX_DATE;
 import static com.scottlogic.deg.common.util.Defaults.ISO_MIN_DATE;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MAX_LIMIT;
-import static com.scottlogic.deg.generator.utils.Defaults.DATETIME_MIN_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MAX_LIMIT;
+import static com.scottlogic.deg.generator.utils.GeneratorDefaults.DATETIME_MIN_LIMIT;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.core.Is.is;
 import static org.hamcrest.core.IsNot.not;