Add RFC6901 json pointer support

now Path can convert RFC6901 style path to json path
for example
Path.ofJosnPointer("/abc/0") can convert to Path.of(".abc.[0]")

Author: leonchen83

src/main/java/com/redislabs/modules/rejson/Path.java

@@ -60,6 +60,10 @@ public static Path of(final String strPath) {
         return new Path(strPath);
     }
 
+    public static Path ofJosnPointer(final String strPath) {
+        return new Path(parse(strPath));
+    }
+    
     @Override
     public boolean equals(Object obj) {
         if (obj == null) return false;
@@ -72,4 +76,88 @@ public boolean equals(Object obj) {
     public int hashCode() {
         return strPath.hashCode();
     }
+    
+    private static String parse(String path) {
+        if (path == null) {
+            throw new NullPointerException("Json Pointer Path cannot be null.");
+        }
+        if (path.isEmpty()) {
+            throw new IllegalArgumentException("Json Pointer Path cannot be empty.");
+        }
+        if (path.charAt(0) != '/') {
+            throw new IllegalArgumentException("Json Pointer Path must start with '/'.");
+        }
+        if (path.length() == 1) {
+            // only contains '/'
+            return ROOT_PATH.toString();
+        }
+        char[] ary = path.toCharArray();
+        StringBuilder r = new StringBuilder(ary.length);
+        StringBuilder builder = new StringBuilder();
+        boolean num = true;
+        char prev = '/';
+        for (int i = 1; i < ary.length; i++) {
+            char c = ary[i];
+            switch (c) {
+            case '~':
+                if (prev == '~') {
+                    num = false;
+                    builder.append('~');
+                }
+                break;
+            case '/':
+                if (prev == '~') {
+                    num = false;
+                    builder.append('~');
+                }
+                if (builder.length() > 0 && num) {
+                    r.append(".[" + builder + "]");
+                } else {
+                    r.append("." + builder);
+                }
+                num = true;
+                builder.setLength(0);
+                break;
+            case '0':
+                if (prev == '~') {
+                    num = false;
+                    builder.append("~");
+                } else {
+                    builder.append(c);
+                }
+                break;
+            case '1':
+                if (prev == '~') {
+                    num = false;
+                    builder.append("/");
+                } else {
+                    builder.append(c);
+                }
+                break;
+            default:
+                if (prev == '~') {
+                    num = false;
+                    builder.append('~');
+                }
+                if (c < '0' || c > '9') {
+                    num = false;
+                }
+                builder.append(c);
+                break;
+            }
+            prev = c;
+        }
+        if (prev == '~') {
+            num = false;
+            builder.append("~");
+        }
+        if (builder.length() > 0) {
+            if (num) {
+                r.append(".[" + builder + "]");
+            } else {
+                r.append("." + builder);
+            }
+        }
+        return r.toString();
+    }
 }

src/test/java/com/redislabs/modules/rejson/PathTest.java

@@ -31,4 +31,20 @@ public void testPathHashCode() {
         assertEquals(Path.of(".a.b.c").hashCode(), Path.of(".a.b.c").hashCode());
         assertNotEquals(Path.of(".a.b.c").hashCode(), Path.of(".b.c").hashCode());
     }
+    
+    @Test
+    public void testJsonPointer() {
+        assertEquals(Path.ofJosnPointer("/"), Path.ROOT_PATH);
+        assertEquals(Path.ofJosnPointer("/a/b/c"), Path.of(".a.b.c"));
+        assertEquals(Path.ofJosnPointer("/a/0/c"), Path.of(".a.[0].c"));
+        assertEquals(Path.ofJosnPointer("/a/0b/c"), Path.of(".a.0b.c"));
+        assertEquals(Path.ofJosnPointer("/ab/cd/1010"), Path.of(".ab.cd.[1010]"));
+        assertEquals(Path.ofJosnPointer("/a/b/c").hashCode(), Path.of(".a.b.c").hashCode());
+
+        //escape test
+        assertEquals(Path.ofJosnPointer("/a/~0/c"), Path.of(".a.~.c"));
+        assertEquals(Path.ofJosnPointer("/a/~1/c"), Path.of(".a./.c"));
+        assertEquals(Path.ofJosnPointer("/a/~~/c"), Path.of(".a.~~.c"));
+        assertEquals(Path.ofJosnPointer("/~/~~~/~~"), Path.of(".~.~~~.~~"));
+    }
 }