Added Header interface and class implementation

Author: DvirDukhan

src/main/java/com/redislabs/redisgraph/Header.java

@@ -0,0 +1,20 @@
+package com.redislabs.redisgraph;
+
+import java.util.List;
+
+public interface Header {
+
+
+    public enum ResultSetColumnTypes {
+        COLUMN_UNKNOWN,
+        COLUMN_SCALAR,
+        COLUMN_NODE,
+        COLUMN_RELATION;
+
+    }
+
+
+    List<String> getSchemaNames();
+
+    List<ResultSetColumnTypes> getSchemaTypes();
+}

src/main/java/com/redislabs/redisgraph/impl/HeaderImpl.java

@@ -0,0 +1,95 @@
+package com.redislabs.redisgraph.impl;
+
+import com.redislabs.redisgraph.Header;
+import redis.clients.jedis.util.SafeEncoder;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Query result header interface implementation
+ */
+public class HeaderImpl implements Header {
+
+    //members
+    private final List<List<Object>> raw;
+    private final List<ResultSetColumnTypes> schemaTypes = new ArrayList<>();
+    private final List<String> schemaNames = new ArrayList<>();
+
+
+    /**
+     * Parameterized constructor
+     * A raw representation of a header (query response schema) is a list.
+     * Each entry in the list is a tuple (list of size 2).
+     * tuple[0] represents the type of the column, and tuple[1] represents the name of the column.
+     *
+     * @param raw - raw representation of a header
+     */
+    public HeaderImpl(List<List<Object>> raw) {
+        this.raw = raw;
+    }
+
+
+    /**
+     * @return a list of column names, ordered by they appearance in the query
+     */
+    @Override
+    public List<String> getSchemaNames() {
+        if (schemaNames.size() == 0) {
+            buildSchema();
+        }
+        return schemaNames;
+    }
+
+    /**
+     * @return a list of column types, ordered by they appearance in the query
+     */
+    @Override
+    public List<ResultSetColumnTypes> getSchemaTypes() {
+        if (schemaTypes.size() == 0) {
+            buildSchema();
+        }
+        return schemaTypes;
+    }
+
+    /**
+     * Extracts schema names and types from the raw representation
+     */
+    private void buildSchema() {
+        for (List<Object> tuple : this.raw) {
+
+            //get type
+            ResultSetColumnTypes type = ResultSetColumnTypes.values()[(int) (long) tuple.get(0)];
+            //get text
+            String text = SafeEncoder.encode((byte[]) tuple.get(1));
+            if (type != null) {
+                schemaTypes.add(type);
+                schemaNames.add(text);
+            }
+        }
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof HeaderImpl)) return false;
+        HeaderImpl header = (HeaderImpl) o;
+        return Objects.equals(getSchemaTypes(), header.getSchemaTypes()) &&
+                Objects.equals(getSchemaNames(), header.getSchemaNames());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getSchemaTypes(), getSchemaNames());
+    }
+
+    @Override
+    public String toString() {
+        final StringBuilder sb = new StringBuilder("HeaderImpl{");
+        sb.append("schemaTypes=").append(schemaTypes);
+        sb.append(", schemaNames=").append(schemaNames);
+        sb.append('}');
+        return sb.toString();
+    }
+}