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Core Jackson abstractions, basic JSON streaming API implementation
package com.fasterxml.jackson.core.json;
import com.fasterxml.jackson.core.*;
/**
* Extension of {@link JsonStreamContext}, which implements
* core methods needed, and also exposes
* more complete API to generator implementation classes.
*/
public class JsonWriteContext extends JsonStreamContext
{
// // // Return values for writeValue()
public final static int STATUS_OK_AS_IS = 0;
public final static int STATUS_OK_AFTER_COMMA = 1;
public final static int STATUS_OK_AFTER_COLON = 2;
public final static int STATUS_OK_AFTER_SPACE = 3; // in root context
public final static int STATUS_EXPECT_VALUE = 4;
public final static int STATUS_EXPECT_NAME = 5;
/**
* Parent context for this context; null for root context.
*/
protected final JsonWriteContext _parent;
// // // Optional duplicate detection
protected DupDetector _dups;
/*
/**********************************************************
/* Simple instance reuse slots; speed up things
/* a bit (10-15%) for docs with lots of small
/* arrays/objects
/**********************************************************
*/
protected JsonWriteContext _child = null;
/*
/**********************************************************
/* Location/state information (minus source reference)
/**********************************************************
*/
/**
* Name of the field of which value is to be parsed; only
* used for OBJECT contexts
*/
protected String _currentName;
/**
* @since 2.5
*/
protected Object _currentValue;
/**
* Marker used to indicate that we just received a name, and
* now expect a value
*/
protected boolean _gotName;
/*
/**********************************************************
/* Life-cycle
/**********************************************************
*/
protected JsonWriteContext(int type, JsonWriteContext parent, DupDetector dups) {
super();
_type = type;
_parent = parent;
_dups = dups;
_index = -1;
}
protected JsonWriteContext reset(int type) {
_type = type;
_index = -1;
_currentName = null;
_gotName = false;
_currentValue = null;
if (_dups != null) { _dups.reset(); }
return this;
}
public JsonWriteContext withDupDetector(DupDetector dups) {
_dups = dups;
return this;
}
@Override
public Object getCurrentValue() {
return _currentValue;
}
@Override
public void setCurrentValue(Object v) {
_currentValue = v;
}
/*
/**********************************************************
/* Factory methods
/**********************************************************
*/
/**
* @deprecated Since 2.3; use method that takes argument
*/
@Deprecated
public static JsonWriteContext createRootContext() { return createRootContext(null); }
public static JsonWriteContext createRootContext(DupDetector dd) {
return new JsonWriteContext(TYPE_ROOT, null, dd);
}
public JsonWriteContext createChildArrayContext() {
JsonWriteContext ctxt = _child;
if (ctxt == null) {
_child = ctxt = new JsonWriteContext(TYPE_ARRAY, this, (_dups == null) ? null : _dups.child());
return ctxt;
}
return ctxt.reset(TYPE_ARRAY);
}
public JsonWriteContext createChildObjectContext() {
JsonWriteContext ctxt = _child;
if (ctxt == null) {
_child = ctxt = new JsonWriteContext(TYPE_OBJECT, this, (_dups == null) ? null : _dups.child());
return ctxt;
}
return ctxt.reset(TYPE_OBJECT);
}
@Override public final JsonWriteContext getParent() { return _parent; }
@Override public final String getCurrentName() { return _currentName; }
public DupDetector getDupDetector() {
return _dups;
}
/**
* Method that writer is to call before it writes a field name.
*
* @return Index of the field entry (0-based)
*/
public int writeFieldName(String name) throws JsonProcessingException {
if (_gotName) {
return JsonWriteContext.STATUS_EXPECT_VALUE;
}
_gotName = true;
_currentName = name;
if (_dups != null) { _checkDup(_dups, name); }
return (_index < 0) ? STATUS_OK_AS_IS : STATUS_OK_AFTER_COMMA;
}
private final void _checkDup(DupDetector dd, String name) throws JsonProcessingException {
if (dd.isDup(name)) { throw new JsonGenerationException("Duplicate field '"+name+"'"); }
}
public int writeValue() {
// Most likely, object:
if (_type == TYPE_OBJECT) {
if (!_gotName) {
return STATUS_EXPECT_NAME;
}
_gotName = false;
++_index;
return STATUS_OK_AFTER_COLON;
}
// Ok, array?
if (_type == TYPE_ARRAY) {
int ix = _index;
++_index;
return (ix < 0) ? STATUS_OK_AS_IS : STATUS_OK_AFTER_COMMA;
}
// Nope, root context
// No commas within root context, but need space
++_index;
return (_index == 0) ? STATUS_OK_AS_IS : STATUS_OK_AFTER_SPACE;
}
// // // Internally used abstract methods
protected void appendDesc(StringBuilder sb) {
if (_type == TYPE_OBJECT) {
sb.append('{');
if (_currentName != null) {
sb.append('"');
// !!! TODO: Name chars should be escaped?
sb.append(_currentName);
sb.append('"');
} else {
sb.append('?');
}
sb.append('}');
} else if (_type == TYPE_ARRAY) {
sb.append('[');
sb.append(getCurrentIndex());
sb.append(']');
} else {
// nah, ROOT:
sb.append("/");
}
}
// // // Overridden standard methods
/**
* Overridden to provide developer writeable "JsonPath" representation
* of the context.
*/
@Override public String toString() {
StringBuilder sb = new StringBuilder(64);
appendDesc(sb);
return sb.toString();
}
}