Populate xpath/ hierarchy

[yangtools.git] / xpath / yang-xpath-api / src / main / java / org / opendaylight / yangtools / yang / xpath / api / YangLiteralExpr.java

diff --git a/xpath/yang-xpath-api/src/main/java/org/opendaylight/yangtools/yang/xpath/api/YangLiteralExpr.java b/xpath/yang-xpath-api/src/main/java/org/opendaylight/yangtools/yang/xpath/api/YangLiteralExpr.java
new file mode 100644 (file)
index 0000000..8aaf104
--- /dev/null
+++ b/xpath/yang-xpath-api/src/main/java/org/opendaylight/yangtools/yang/xpath/api/YangLiteralExpr.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2018 Pantheon Technologies, s.r.o.  All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.yangtools.yang.xpath.api;
+
+import static java.util.Objects.requireNonNull;
+
+import com.google.common.annotations.Beta;
+import org.eclipse.jdt.annotation.Nullable;
+
+/**
+ * An XPath literal expression.
+ *
+ * <p>
+ * Note that a literal may be required to hold a value of {@code instance-identifier} or {@code identityref} type,
+ * when the corresponding {@link YangXPathExpression} was parsed from reference String specification defined in RFC7950.
+ * When such conversion is required, it should be performed through
+ * {@link YangXPathExpression#interpretAsQName(YangLiteralExpr)} or
+ * {@link YangXPathExpression#interpretAsInstanceIdentifier(YangLiteralExpr)}.
+ *
+ * <p>
+ * A more type-safe alternative is {@link YangQNameExpr}, which should be preferred and used whenever possible.
+ *
+ * @author Robert Varga
+ */
+@Beta
+public final class YangLiteralExpr implements YangExpr {
+    private static final long serialVersionUID = 1L;
+    private static final YangLiteralExpr EMPTY = new YangLiteralExpr("");
+
+    private final String literal;
+
+    YangLiteralExpr(final String literal) {
+        this.literal = requireNonNull(literal);
+    }
+
+    public static YangLiteralExpr empty() {
+        return EMPTY;
+    }
+
+    public static YangLiteralExpr of(final String literal) {
+        return literal.isEmpty() ? EMPTY : new YangLiteralExpr(literal);
+    }
+
+    public String getLiteral() {
+        return literal;
+    }
+
+    @Override
+    public int hashCode() {
+        return literal.hashCode();
+    }
+
+    @Override
+    public boolean equals(final @Nullable Object obj) {
+        return this == obj || obj instanceof YangLiteralExpr && literal.equals(((YangLiteralExpr) obj).literal);
+    }
+
+    @Override
+    public String toString() {
+        return literal;
+    }
+
+    protected Object readResolve() {
+        return literal.isEmpty() ? EMPTY : this;
+    }
+}