Java tutorial
package com.fasterxml.jackson.core.json; import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.core.io.CharTypes; /** * Extension of {@link JsonStreamContext}, which implements * core methods needed, and also exposes * more complete API to parser implementation classes. */ public final class JsonReadContext extends JsonStreamContext { // // // Configuration protected final JsonReadContext _parent; // // // Location information (minus source reference) protected int _lineNr; protected int _columnNr; protected String _currentName; /* /********************************************************** /* Simple instance reuse slots; speeds up things /* a bit (10-15%) for docs with lots of small /* arrays/objects (for which allocation was /* visible in profile stack frames) /********************************************************** */ protected JsonReadContext _child = null; /* /********************************************************** /* Instance construction, reuse /********************************************************** */ public JsonReadContext(JsonReadContext parent, int type, int lineNr, int colNr) { super(); _type = type; _parent = parent; _lineNr = lineNr; _columnNr = colNr; _index = -1; } protected void reset(int type, int lineNr, int colNr) { _type = type; _index = -1; _lineNr = lineNr; _columnNr = colNr; _currentName = null; } // // // Factory methods public static JsonReadContext createRootContext(int lineNr, int colNr) { return new JsonReadContext(null, TYPE_ROOT, lineNr, colNr); } public static JsonReadContext createRootContext() { return new JsonReadContext(null, TYPE_ROOT, 1, 0); } public JsonReadContext createChildArrayContext(int lineNr, int colNr) { JsonReadContext ctxt = _child; if (ctxt == null) { _child = ctxt = new JsonReadContext(this, TYPE_ARRAY, lineNr, colNr); return ctxt; } ctxt.reset(TYPE_ARRAY, lineNr, colNr); return ctxt; } public JsonReadContext createChildObjectContext(int lineNr, int colNr) { JsonReadContext ctxt = _child; if (ctxt == null) { _child = ctxt = new JsonReadContext(this, TYPE_OBJECT, lineNr, colNr); return ctxt; } ctxt.reset(TYPE_OBJECT, lineNr, colNr); return ctxt; } /* /********************************************************** /* Abstract method implementation /********************************************************** */ @Override public String getCurrentName() { return _currentName; } @Override public JsonReadContext getParent() { return _parent; } /* /********************************************************** /* Extended API /********************************************************** */ /** * @return Location pointing to the point where the context * start marker was found */ public JsonLocation getStartLocation(Object srcRef) { /* We don't keep track of offsets at this level (only * reader does) */ long totalChars = -1L; return new JsonLocation(srcRef, totalChars, _lineNr, _columnNr); } /* /********************************************************** /* State changes /********************************************************** */ public boolean expectComma() { /* Assumption here is that we will be getting a value (at least * before calling this method again), and * so will auto-increment index to avoid having to do another call */ int ix = ++_index; // starts from -1 return (_type != TYPE_ROOT && ix > 0); } public void setCurrentName(String name) { _currentName = name; } /* /********************************************************** /* Overridden standard methods /********************************************************** */ /** * Overridden to provide developer readable "JsonPath" representation * of the context. */ @Override public String toString() { StringBuilder sb = new StringBuilder(64); switch (_type) { case TYPE_ROOT: sb.append("/"); break; case TYPE_ARRAY: sb.append('['); sb.append(getCurrentIndex()); sb.append(']'); break; case TYPE_OBJECT: sb.append('{'); if (_currentName != null) { sb.append('"'); CharTypes.appendQuoted(sb, _currentName); sb.append('"'); } else { sb.append('?'); } sb.append('}'); break; } return sb.toString(); } }