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Implement additional JsonParser methods to obtain and skip JsonValues
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Signed-off-by: Michael Edgar <michael@xlate.io>
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@MikeEdgar
MikeEdgar committed Feb 15, 2024
1 parent 5931d48 commit 9fa6197
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Showing 5 changed files with 450 additions and 140 deletions.
11 changes: 10 additions & 1 deletion src/main/java/io/xlate/yamljson/Yaml.java
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@
import jakarta.json.JsonReaderFactory;
import jakarta.json.JsonWriter;
import jakarta.json.JsonWriterFactory;
import jakarta.json.spi.JsonProvider;
import jakarta.json.stream.JsonGenerator;
import jakarta.json.stream.JsonGeneratorFactory;
import jakarta.json.stream.JsonParser;
Expand Down Expand Up @@ -123,7 +124,15 @@ private Settings() {
private Yaml() {
}

private static YamlProvider provider() {
/**
* Obtain the underlying YAML provider used by the other methods of this
* class. This may be useful in cases where a JsonProvider is needed.
* <p>
* Repeat calls to this method will return the same instance.
*
* @return a YAML provider implementation of the JsonProvider contract
*/
public static JsonProvider provider() {
return PROVIDER;
}

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229 changes: 226 additions & 3 deletions src/main/java/io/xlate/yamljson/YamlParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,14 +25,21 @@
import java.util.Deque;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.logging.Logger;

import jakarta.json.JsonArray;
import jakarta.json.JsonArrayBuilder;
import jakarta.json.JsonException;
import jakarta.json.JsonObject;
import jakarta.json.JsonObjectBuilder;
import jakarta.json.JsonValue;
import jakarta.json.spi.JsonProvider;
import jakarta.json.stream.JsonLocation;
import jakarta.json.stream.JsonParser;
import jakarta.json.stream.JsonParsingException;
Expand Down Expand Up @@ -81,6 +88,7 @@ enum NumberType {
static final BigDecimal UNSET_NUMBER = new BigDecimal(0);
static final YamlLocation UNKNOWN_LOCATION = new YamlLocation(-1, -1, -1);

final JsonProvider jsonProvider = JsonProvider.provider();
final Reader yamlSource;
final Iterator<E> yamlEvents;
final Map<String, ?> properties;
Expand All @@ -103,6 +111,7 @@ enum NumberType {
BigDecimal currentNumber;

final Boolean[] valueIsKey = new Boolean[200];
final List<Event> eventStack = new ArrayList<>();
int depth = -1;
final Deque<AnchorMetadata> anchorStack = new ArrayDeque<>();

Expand Down Expand Up @@ -456,16 +465,18 @@ Boolean isKeyExpected() {
return depth > -1 ? this.valueIsKey[depth] : null;
}

void incrementDepth(Boolean keyExpected) {
void incrementDepth(Event levelEvent, Boolean keyExpected) {
if (isKeyExpected() != null) {
this.valueIsKey[depth] = Boolean.TRUE;
}

depth++;
this.valueIsKey[depth] = keyExpected;
eventStack.add(depth, levelEvent);
}

void decrementDepth() {
eventStack.remove(depth);
depth--;
}

Expand Down Expand Up @@ -501,7 +512,7 @@ boolean enqueueEvent(E yamlEvent) {

case "SequenceStart":
addAnchorMetadata(getAnchor(yamlEvent));
incrementDepth(null);
incrementDepth(Event.START_ARRAY, null);
enqueue(yamlEvent, Event.START_ARRAY, NumberType.NONE, "", UNSET_NUMBER);
break;

Expand All @@ -513,7 +524,7 @@ boolean enqueueEvent(E yamlEvent) {

case "MappingStart":
addAnchorMetadata(getAnchor(yamlEvent));
incrementDepth(Boolean.TRUE);
incrementDepth(Event.START_OBJECT, Boolean.TRUE);
enqueue(yamlEvent, Event.START_OBJECT, NumberType.NONE, "", UNSET_NUMBER);
break;

Expand Down Expand Up @@ -635,6 +646,11 @@ public Event next() {
return currentEvent;
}

@Override
public Event currentEvent() {
return currentEvent;
}

@Override
public void close() {
try {
Expand Down Expand Up @@ -710,6 +726,213 @@ JsonLocation getLocation(E yamlEvent) {
return location;
}

@Override
public JsonValue getValue() {
return getJsonValue(null);
}

@Override
public JsonObject getObject() {
return (JsonObject) getJsonValue(Event.START_OBJECT);
}

@Override
public void skipObject() {
skip(Event.START_OBJECT);
}

@Override
public JsonArray getArray() {
return (JsonArray) getJsonValue(Event.START_ARRAY);
}

@Override
public void skipArray() {
skip(Event.START_ARRAY);
}

JsonValue getJsonValue(Event requiredEvent) {
Event event = currentEvent();

if (requiredEvent != null && event != requiredEvent) {
throw new IllegalStateException("Expected current state to be " + requiredEvent + ", but got [" + currentEvent() + ']');
}

Deque<Object> builders = new ArrayDeque<>();
Deque<String> keyNames = new LinkedList<>();
Object rootBuilder = null;
String keyName = null;
JsonValue rootValue = null;
int valueDepth = 0;
int iteration = 0;

do {
event = currentOrNextEvent(iteration++, event);

switch (event) {
case KEY_NAME:
keyName = getString();
break;
case START_ARRAY:
rootBuilder = beginStructure(builders, keyNames, keyName, jsonProvider.createArrayBuilder());
keyName = null;
valueDepth++;
break;
case START_OBJECT:
rootBuilder = beginStructure(builders, keyNames, keyName, jsonProvider.createObjectBuilder());
keyName = null;
valueDepth++;
break;
case END_ARRAY:
case END_OBJECT:
endStructure(builders, keyNames);
valueDepth--;
break;
default:
JsonValue parsedValue = getParsedValue(event);

if (builders.isEmpty()) {
rootValue = parsedValue;
} else {
addValue(builders.peekLast(), keyName, parsedValue);
}

keyName = null;
break;
}
} while (valueDepth > 0);

if (rootBuilder != null) {
rootValue = build(rootBuilder);
} else if (rootValue == null) {
// method was called at KEY_NAME
Objects.requireNonNull(keyName, "Expected value for KEY_NAME, but it was null");
rootValue = jsonProvider.createValue(keyName);
}

return rootValue;
}

void skip(Event structuralEvent) {
final int terminalDepth = eventStack.lastIndexOf(structuralEvent);

if (terminalDepth < 0) {
return;
}

Event event = currentEvent();
int valueDepth;
int iteration = 0;

/*
* Accounting for the fact that `depth` was already modified for start/end structure events
* and adjusting for the first pass through the loop.
*/
switch (event) {
case START_ARRAY:
case START_OBJECT:
valueDepth = depth - 1;
break;
case END_ARRAY:
case END_OBJECT:
valueDepth = depth + 1;
break;
default:
valueDepth = depth;
break;
}

do {
event = currentOrNextEvent(iteration++, event);

switch (event) {
case START_ARRAY:
case START_OBJECT:
valueDepth++;
break;

case END_ARRAY:
case END_OBJECT:
valueDepth--;
break;

default:
break;
}
} while (valueDepth >= terminalDepth);
}

Event currentOrNextEvent(int iteration, Event event) {
return iteration > 0 ? next() : event;
}

Object beginStructure(Deque<Object> builders, Deque<String> keyNames, String keyName, Object builder) {
builders.add(builder);
keyNames.push(keyName);

return builders.peek();
}

void endStructure(Deque<Object> builders, Deque<String> keyNames) {
final Object completedStructure = builders.removeLast();

if (builders.isEmpty()) {
// Nothing to do, this is the top level builder
} else {
final String keyName = keyNames.pop();
final JsonValue value = build(completedStructure);
final Object parentBuilder = builders.peekLast();

addValue(parentBuilder, keyName, value);
}
}

JsonValue build(Object builder) {
final JsonValue value;

if (builder instanceof JsonObjectBuilder) {
value = ((JsonObjectBuilder) builder).build();
} else {
value = ((JsonArrayBuilder) builder).build();
}

return value;
}

JsonValue getParsedValue(Event event) {
JsonValue value;

switch (event) {
case VALUE_TRUE:
value = JsonValue.TRUE;
break;
case VALUE_FALSE:
value = JsonValue.FALSE;
break;
case VALUE_NULL:
value = JsonValue.NULL;
break;
case VALUE_NUMBER:
value = jsonProvider.createValue(getBigDecimal());
break;
case VALUE_STRING:
value = jsonProvider.createValue(getString());
break;
default:
throw new IllegalStateException("Non-value event: " + event);
}

return value;
}

void addValue(Object builder, String keyName, JsonValue value) {
if (keyName != null) {
((JsonObjectBuilder) builder).add(keyName, value);
} else {
((JsonArrayBuilder) builder).add(value);
}
}

protected abstract M getMark(E event);
protected abstract int getMarkLine(M mark);
protected abstract int getMarkColumn(M mark);
Expand Down
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