Added equals

Signed-off-by: Emmanuel Bigeon <emmanuel@bigeon.fr>

gclc/src/main/java/net/bigeon/gclc/tools/ConstantString.java

@@ -77,7 +77,7 @@ public class ConstantString implements StringProvider {
     /** Create a provider for a string.
      *
      * @param string the string */
-    public ConstantString(String string) {
+    public ConstantString(final String string) {
         this.string = string;
     }
 
@@ -87,4 +87,38 @@ public class ConstantString implements StringProvider {
     public String apply() {
         return string;
     }
+
+    /* (non-Javadoc)
+     * @see java.lang.Object#hashCode() */
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((string == null) ? 0 : string.hashCode());
+        return result;
+    }
+
+    /* (non-Javadoc)
+     * @see java.lang.Object#equals(java.lang.Object) */
+    @Override
+    public boolean equals(final Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        final ConstantString other = (ConstantString) obj;
+        if (string == null) {
+            if (other.string != null) {
+                return false;
+            }
+        } else if (!string.equals(other.string)) {
+            return false;
+        }
+        return true;
+    }
 }