Allow arbitrary expression IDs (closes #163)

src/main/java/com/gliwka/hyperscan/wrapper/Database.java

@@ -19,7 +19,7 @@
  * Database containing compiled expressions ready for scanning using the Scanner
  */
 public class Database implements Closeable {
-    private final Expression[] expressions;
+    private final Map<Integer, Expression> expressions;
     private final int expressionCount;
 
     private NativeDatabase database;
@@ -38,13 +38,17 @@ private Database(NativeDatabase database, List<Expression> expressions) {
 
         boolean hasIds = expressions.get(0).getId() != null;
 
+        this.expressions = new HashMap<>(expressionCount);
         if (hasIds) {
-            int maxId = expressions.stream().mapToInt(Expression::getId).max().getAsInt();
-            this.expressions = new Expression[maxId + 1];
-
-            expressions.forEach(expression -> this.expressions[expression.getId()] = expression);
+            for (Expression expression : expressions) {
+                if (this.expressions.put(expression.getId(), expression) != null)
+                    throw new IllegalStateException("Expression ID must be unique within a Database.");
+            }
         } else {
-            this.expressions = expressions.toArray(new Expression[0]);
+            int i = 0;
+            for (Expression expression : expressions) {
+                this.expressions.put(i++, expression);
+            }
         }
     }
 
@@ -94,7 +98,6 @@ public static Database compile(List<Expression> expressions) throws CompileError
             throw new IllegalStateException("You can't mix expressions with and without id's in a single database");
         }
 
-
         for (int i = 0; i < expressionsSize; i++) {
             flags[i] = expressions.get(i).getFlagBits();
 
@@ -141,11 +144,7 @@ public long getSize() {
     }
 
     Expression getExpression(int id) {
-        return expressions[id];
-    }
-
-    int getExpressionCount() {
-        return expressionCount;
+        return expressions.get(id);
     }
 
     @Override
@@ -179,7 +178,7 @@ public void save(OutputStream expressionsOut, OutputStream databaseOut) throws I
         DataOutputStream expressionsDataOut = new DataOutputStream(expressionsOut);
         // How many expressions will be present. We need this to know when to stop reading.
         expressionsDataOut.writeInt(expressionCount);
-        for (Expression expression : expressions) {
+        for (Expression expression : expressions.values()) {
             if (expression == null) {
                 continue;
             }
@@ -289,13 +288,13 @@ public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         Database database = (Database) o;
-        return expressionCount == database.expressionCount && Arrays.deepEquals(expressions, database.expressions);
+        return expressionCount == database.expressionCount && expressions.equals(database.expressions);
     }
 
     @Override
     public int hashCode() {
         int result = Objects.hash(expressionCount);
-        result = 31 * result + Arrays.hashCode(expressions);
+        result = 31 * result + expressions.hashCode();
         return result;
     }
 }

src/main/java/com/gliwka/hyperscan/wrapper/Expression.java

@@ -16,8 +16,8 @@
 @ToString
 public class Expression {
     @Getter @NonNull private final String expression;
-    @Getter private EnumSet<ExpressionFlag> flags = EnumSet.of(ExpressionFlag.NO_FLAG);
-    @Getter private Integer id;
+    @Getter private final EnumSet<ExpressionFlag> flags;
+    @Getter private final Integer id;
 
     /**
      * Represents the validation results for a expression
@@ -37,34 +37,32 @@ public static class ValidationResult {
     }
 
     public Expression(@NonNull String expression) {
-        this.expression = expression;
+        this(expression,  EnumSet.of(ExpressionFlag.NO_FLAG), null);
     }
 
     public Expression(@NonNull String expression, Integer id) {
-        this.expression = expression;
-        this.id = id;
+        this(expression,  EnumSet.of(ExpressionFlag.NO_FLAG), id);
     }
 
     public Expression(@NonNull String expression, @NonNull EnumSet<ExpressionFlag> flags) {
-        this.expression = expression;
-        this.flags = flags;
+        this(expression, flags, null);
     }
 
     public Expression(@NonNull String expression, @NonNull ExpressionFlag flag) {
-        this.expression = expression;
-        this.flags = EnumSet.of(flag);
+        this(expression, EnumSet.of(flag), null);
     }
 
     public Expression(@NonNull String expression, @NonNull EnumSet<ExpressionFlag> flags, Integer id) {
+        if (id != null && id < 0)
+            throw new IllegalArgumentException("id must be >=0: " + id);
+
         this.expression = expression;
         this.flags = flags;
         this.id = id;
     }
 
     public Expression(@NonNull String expression, @NonNull ExpressionFlag flag, Integer id) {
-        this.expression = expression;
-        this.flags = EnumSet.of(flag);
-        this.id = id;
+        this(expression, EnumSet.of(flag), id);
     }
 
     public ValidationResult validate() {