Merge pull request #15 from fauna/feature/BT-4418-utf8faunareader_rea…

…d_string

[BT-4418] FaunaParser String values

build.gradle

@@ -32,7 +32,12 @@ project(':faunaJava') {
     dependencies {
         implementation project(':common')
 
+        implementation "com.fasterxml.jackson.core:jackson-core:${jacksonVersion}"
+        implementation "com.fasterxml.jackson.core:jackson-annotations:${jacksonVersion}"
+        implementation "com.fasterxml.jackson.core:jackson-databind:${jacksonVersion}"
+
         testImplementation "org.junit.jupiter:junit-jupiter-api:${junitVersion}"
+        testImplementation 'junit:junit:4.13.2'
         testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:${junitVersion}"
         testImplementation "org.mockito:mockito-core:${mockitoVersion}"
     }

faunaJava/src/main/java/com/fauna/exception/SerializationException.java

@@ -0,0 +1,12 @@
+package com.fauna.exception;
+
+public class SerializationException extends RuntimeException {
+
+    public SerializationException(String message) {
+        super(message);
+    }
+
+    public SerializationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

faunaJava/src/main/java/com/fauna/serialization/FaunaParser.java

@@ -0,0 +1,115 @@
+package com.fauna.serialization;
+
+import static com.fauna.common.enums.FaunaTokenType.END_ARRAY;
+import static com.fauna.common.enums.FaunaTokenType.END_DOCUMENT;
+import static com.fauna.common.enums.FaunaTokenType.END_OBJECT;
+import static com.fauna.common.enums.FaunaTokenType.END_PAGE;
+import static com.fauna.common.enums.FaunaTokenType.END_REF;
+import static com.fauna.common.enums.FaunaTokenType.NONE;
+
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import com.fauna.common.enums.FaunaTokenType;
+import com.fauna.exception.SerializationException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+import java.util.Stack;
+
+/**
+ * Represents a reader that provides fast, non-cached, forward-only access to serialized data.
+ */
+public class FaunaParser {
+
+    private static final String INT_TAG = "@int";
+    private static final String LONG_TAG = "@long";
+    private static final String DOUBLE_TAG = "@double";
+    private static final String TIME_TAG = "@time";
+    private static final String DATE_TAG = "@date";
+    private static final String REF_TAG = "@ref";
+    private static final String DOC_TAG = "@doc";
+    private static final String MOD_TAG = "@mod";
+    private static final String SET_TAG = "@set";
+    private static final String OBJECT_TAG = "@object";//TODO Understand Module
+    private final JsonParser jsonParser;
+    private final Stack<Object> tokenStack = new Stack<>();
+    private FaunaTokenType currentFaunaTokenType;
+    private FaunaTokenType bufferedFaunaTokenType;
+    private String taggedTokenValue;
+
+    public FaunaParser(InputStream body) throws IOException {
+        JsonFactory factory = new JsonFactory();
+        this.jsonParser = factory.createParser(body);
+        currentFaunaTokenType = NONE;
+    }
+
+    public FaunaParser(JsonParser jsonParser) {
+        this.jsonParser = jsonParser;
+        currentFaunaTokenType = NONE;
+    }
+
+    public JsonToken getCurrentTokenType() {
+        return jsonParser.currentToken();
+    }
+
+    private final Set<FaunaTokenType> closers = new HashSet<>(Arrays.asList(
+        END_OBJECT,
+        END_PAGE,
+        END_DOCUMENT,
+        END_REF,
+        END_ARRAY
+    ));
+
+    public boolean read() {
+        taggedTokenValue = null;
+
+        if (bufferedFaunaTokenType != null) {
+            currentFaunaTokenType = bufferedFaunaTokenType;
+            bufferedFaunaTokenType = null;
+            if (closers.contains(currentFaunaTokenType)) {
+                tokenStack.pop();
+            }
+            return true;
+        }
+
+        if (!advance()) {
+            return false;
+        }
+
+        JsonToken currentToken = jsonParser.currentToken();
+        if (currentToken != null) {
+            switch (currentToken) {
+                case VALUE_STRING:
+                    currentFaunaTokenType = FaunaTokenType.STRING;
+                    break;
+                default:
+                    throw new SerializationException(
+                        "Unhandled JSON token type " + currentToken + ".");
+            }
+        } else {
+            return false;
+        }
+
+        return true;
+    }
+
+    private boolean advance() {
+        try {
+            return Objects.nonNull(jsonParser.nextToken());
+        } catch (IOException e) {
+            throw new SerializationException("Failed to advance underlying JSON reader.", e);
+        }
+    }
+
+    public String getValueAsString() {
+        try {
+            return jsonParser.getValueAsString();
+        } catch (IOException e) {
+            throw new RuntimeException("Error reading current token as String", e);
+        }
+    }
+}

faunaJava/src/test/java/com/fauna/serialization/FaunaParserTest.java

@@ -0,0 +1,53 @@
+package com.fauna.serialization;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import com.fauna.common.enums.FaunaTokenType;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+
+
+class FaunaParserTest {
+
+    @Test
+    public void testGetValueAsString() throws IOException {
+        InputStream inputStream = new ByteArrayInputStream("\"hello\"".getBytes());
+        FaunaParser reader = new FaunaParser(inputStream);
+
+        List<Map.Entry<FaunaTokenType, Object>> expectedTokens = List.of(
+            Map.entry(FaunaTokenType.STRING, "hello")
+        );
+
+        assertReader(reader, expectedTokens);
+    }
+
+    private static void assertReader(FaunaParser reader,
+        List<Map.Entry<FaunaTokenType, Object>> tokens) {
+        for (Map.Entry<FaunaTokenType, Object> entry : tokens) {
+            reader.read();
+            assertNotNull(entry.getKey());
+            assertNotNull(reader.getCurrentTokenType());
+            assertEquals(entry.getKey(), FaunaTokenType.STRING);
+
+            switch (entry.getKey()) {
+                case FIELD_NAME:
+                case STRING:
+                    assertEquals(entry.getValue(), reader.getValueAsString());
+                    break;
+                default:
+                    assertNull(entry.getValue() == null);
+                    break;
+            }
+        }
+
+        assertFalse(reader.read());
+    }
+
+}

gradle.properties

@@ -1,4 +1,5 @@
 version=0.1.0
 
 junitVersion=5.10.0
-mockitoVersion=5.6.0
+mockitoVersion=5.6.0
+jacksonVersion=2.15.3