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// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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// * with the License.  You may obtain a copy of the License at                                                              *
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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
// *                                                                                                                         *
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// ***************************************************************************************************************************
package org.apache.juneau.parser;

import static org.apache.juneau.internal.StringUtils.*;
import static org.apache.juneau.parser.Parser.*;

import java.io.*;
import java.lang.reflect.*;
import java.util.*;

import org.apache.juneau.*;
import org.apache.juneau.annotation.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.transform.*;
import org.apache.juneau.utils.*;

/**
 * Session object that lives for the duration of a single use of {@link Parser}.
 *
 * <p>
 * This class is NOT thread safe.
 * It is typically discarded after one-time use although it can be reused against multiple inputs.
 */
public abstract class ParserSession extends BeanSession {

   private final Parser ctx;
   private final Method javaMethod;
   private final Object outer;

   // Writable properties.
   private BeanPropertyMeta currentProperty;
   private ClassMeta<?> currentClass;
   private final ParserListener listener;

   private Position mark = new Position(-1);

   private ParserPipe pipe;

   /**
    * Create a new session using properties specified in the context.
    *
    * @param ctx
    *    The context creating this session object.
    *    The context contains all the configuration settings for this object.
    * @param args
    *    Runtime session arguments.
    */
   protected ParserSession(Parser ctx, ParserSessionArgs args) {
      super(ctx, args == null ? ParserSessionArgs.DEFAULT : args);
      args = args == null ? ParserSessionArgs.DEFAULT : args;
      this.ctx = ctx;
      javaMethod = args.javaMethod;
      outer = args.outer;
      listener = getInstanceProperty(PARSER_listener, ParserListener.class, ctx.getListener());
   }

   /**
    * Default constructor.
    *
    * @param args
    *    Runtime session arguments.
    */
   protected ParserSession(ParserSessionArgs args) {
      this(Parser.DEFAULT, args);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Abstract methods
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Workhorse method.
    *
    * <p>
    * Subclasses are expected to implement this method.
    *
    * @param pipe Where to get the input from.
    * @param type
    *    The class type of the object to create.
    *    If <jk>null</jk> or <code>Object.<jk>class</jk></code>, object type is based on what's being parsed.
    *    For example, when parsing JSON text, it may return a <c>String</c>, <c>Number</c>,
    *    <c>OMap</c>, etc...
    * @param <T> The class type of the object to create.
    * @return The parsed object.
    * @throws IOException Thrown by underlying stream.
    * @throws ParseException Malformed input encountered.
    * @throws ExecutableException Exception occurred on invoked constructor/method/field.
    */
   protected abstract <T> T doParse(ParserPipe pipe, ClassMeta<T> type) throws IOException, ParseException, ExecutableException;

   /**
    * Returns <jk>true</jk> if this parser subclasses from {@link ReaderParser}.
    *
    * @return <jk>true</jk> if this parser subclasses from {@link ReaderParser}.
    */
   public abstract boolean isReaderParser();


   //-----------------------------------------------------------------------------------------------------------------
   // Other methods
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Wraps the specified input object into a {@link ParserPipe} object so that it can be easily converted into
    * a stream or reader.
    *
    * @param input
    *    The input.
    *    <br>For character-based parsers, this can be any of the following types:
    *    <ul>
    *       <li><jk>null</jk>
    *       <li>{@link Reader}
    *       <li>{@link CharSequence}
    *       <li>{@link InputStream} containing UTF-8 encoded text (or whatever the encoding specified by
    *          {@link ReaderParser#RPARSER_streamCharset}).
    *       <li><code><jk>byte</jk>[]</code> containing UTF-8 encoded text (or whatever the encoding specified by
    *          {@link ReaderParser#RPARSER_streamCharset}).
    *       <li>{@link File} containing system encoded text (or whatever the encoding specified by
    *          {@link ReaderParser#RPARSER_fileCharset}).
    *    </ul>
    *    <br>For byte-based parsers, this can be any of the following types:
    *    <ul>
    *       <li><jk>null</jk>
    *       <li>{@link InputStream}
    *       <li><code><jk>byte</jk>[]</code>
    *       <li>{@link File}
    *       <li>{@link CharSequence} containing encoded bytes according to the {@link InputStreamParser#ISPARSER_binaryFormat} setting.
    *    </ul>
    * @return
    *    A new {@link ParserPipe} wrapper around the specified input object.
    */
   protected ParserPipe createPipe(Object input) {
      return null;
   }

   /**
    * Returns information used to determine at what location in the parse a failure occurred.
    *
    * @return A map, typically containing something like <c>{line:123,column:456,currentProperty:"foobar"}</c>
    */
   public final OMap getLastLocation() {
      OMap m = new OMap();
      if (currentClass != null)
         m.put("currentClass", currentClass.toString(true));
      if (currentProperty != null)
         m.put("currentProperty", currentProperty);
      return m;
   }

   /**
    * Returns the Java method that invoked this parser.
    *
    * <p>
    * When using the REST API, this is the Java method invoked by the REST call.
    * Can be used to access annotations defined on the method or class.
    *
    * @return The Java method that invoked this parser.
   */
   protected final Method getJavaMethod() {
      return javaMethod;
   }

   /**
    * Returns the outer object used for instantiating top-level non-static member classes.
    *
    * <p>
    * When using the REST API, this is the servlet object.
    *
    * @return The outer object.
   */
   protected final Object getOuter() {
      return outer;
   }

   /**
    * Sets the current bean property being parsed for proper error messages.
    *
    * @param currentProperty The current property being parsed.
    */
   protected final void setCurrentProperty(BeanPropertyMeta currentProperty) {
      this.currentProperty = currentProperty;
   }

   /**
    * Sets the current class being parsed for proper error messages.
    *
    * @param currentClass The current class being parsed.
    */
   protected final void setCurrentClass(ClassMeta<?> currentClass) {
      this.currentClass = currentClass;
   }

   /**
    * Trims the specified object if it's a <c>String</c> and {@link #isTrimStrings()} returns <jk>true</jk>.
    *
    * @param o The object to trim.
    * @return The trimmed string if it's a string.
    */
   @SuppressWarnings("unchecked")
   protected final <K> K trim(K o) {
      if (isTrimStrings() && o instanceof String)
         return (K)o.toString().trim();
      return o;

   }

   /**
    * Trims the specified string if {@link ParserSession#isTrimStrings()} returns <jk>true</jk>.
    *
    * @param s The input string to trim.
    * @return The trimmed string, or <jk>null</jk> if the input was <jk>null</jk>.
    */
   protected final String trim(String s) {
      if (isTrimStrings() && s != null)
         return s.trim();
      return s;
   }

   /**
    * Converts the specified <c>OMap</c> into a bean identified by the <js>"_type"</js> property in the map.
    *
    * @param m The map to convert to a bean.
    * @param pMeta The current bean property being parsed.
    * @param eType The current expected type being parsed.
    * @return
    *    The converted bean, or the same map if the <js>"_type"</js> entry wasn't found or didn't resolve to a bean.
    */
   protected final Object cast(OMap m, BeanPropertyMeta pMeta, ClassMeta<?> eType) {

      String btpn = getBeanTypePropertyName(eType);

      Object o = m.get(btpn);
      if (o == null)
         return m;
      String typeName = o.toString();

      ClassMeta<?> cm = getClassMeta(typeName, pMeta, eType);

      if (cm != null) {
         BeanMap<?> bm = m.getBeanSession().newBeanMap(cm.getInnerClass());

         // Iterate through all the entries in the map and set the individual field values.
         for (Map.Entry<String,Object> e : m.entrySet()) {
            String k = e.getKey();
            Object v = e.getValue();
            if (! k.equals(btpn)) {
               // Attempt to recursively cast child maps.
               if (v instanceof OMap)
                  v = cast((OMap)v, pMeta, eType);
               bm.put(k, v);
            }
         }
         return bm.getBean();
      }

      return m;
   }

   /**
    * Give the specified dictionary name, resolve it to a class.
    *
    * @param typeName The dictionary name to resolve.
    * @param pMeta The bean property we're currently parsing.
    * @param eType The expected type we're currently parsing.
    * @return The resolved class, or <jk>null</jk> if the type name could not be resolved.
    */
   protected final ClassMeta<?> getClassMeta(String typeName, BeanPropertyMeta pMeta, ClassMeta<?> eType) {
      BeanRegistry br = null;

      // Resolve via @Beanp(dictionary={})
      if (pMeta != null) {
         br = pMeta.getBeanRegistry();
         if (br != null && br.hasName(typeName))
            return br.getClassMeta(typeName);
      }

      // Resolve via @Bean(dictionary={}) on the expected type where the
      // expected type is an interface with subclasses.
      if (eType != null) {
         br = eType.getBeanRegistry();
         if (br != null && br.hasName(typeName))
            return br.getClassMeta(typeName);
      }

      // Last resort, resolve using the session registry.
      return getBeanRegistry().getClassMeta(typeName);
   }

   /**
    * Specialized warning when an exception is thrown while executing a bean setter.
    *
    * @param p The bean map entry representing the bean property.
    * @param t The throwable that the bean setter threw.
    */
   protected final void onBeanSetterException(BeanPropertyMeta p, Throwable t) {
      if (listener != null)
         listener.onBeanSetterException(this, t, p);
      String prefix = "";
      addWarning("{0}Could not call setValue() on property ''{1}'' of class ''{2}'', exception = {3}", prefix,
         p.getName(), p.getBeanMeta().getClassMeta(), t.getLocalizedMessage());
   }

   /**
    * Method that gets called when an unknown bean property name is encountered.
    *
    * @param propertyName The unknown bean property name.
    * @param beanMap The bean that doesn't have the expected property.
    * @param value The parsed value.
    * @throws ParseException
    *    Automatically thrown if {@link BeanContext#BEAN_ignoreUnknownBeanProperties} setting on this parser is
    *    <jk>false</jk>
    * @param <T> The class type of the bean map that doesn't have the expected property.
    */
   protected final <T> void onUnknownProperty(String propertyName, BeanMap<T> beanMap, Object value) throws ParseException {
      if (propertyName.equals(getBeanTypePropertyName(beanMap.getClassMeta())))
         return;
      if (! isIgnoreUnknownBeanProperties())
         if (value != null || ! isIgnoreUnknownNullBeanProperties())
            throw new ParseException(this,
               "Unknown property ''{0}'' encountered while trying to parse into class ''{1}''", propertyName,
               beanMap.getClassMeta());
      if (listener != null)
         listener.onUnknownBeanProperty(this, propertyName, beanMap.getClassMeta().getInnerClass(), beanMap.getBean());
   }

   /**
    * Parses input into the specified object type.
    *
    * <p>
    * The type can be a simple type (e.g. beans, strings, numbers) or parameterized type (collections/maps).
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bcode w800'>
    *    ReaderParser p = JsonParser.<jsf>DEFAULT</jsf>;
    *
    *    <jc>// Parse into a linked-list of strings.</jc>
    *    List l = p.parse(json, LinkedList.<jk>class</jk>, String.<jk>class</jk>);
    *
    *    <jc>// Parse into a linked-list of beans.</jc>
    *    List l = p.parse(json, LinkedList.<jk>class</jk>, MyBean.<jk>class</jk>);
    *
    *    <jc>// Parse into a linked-list of linked-lists of strings.</jc>
    *    List l = p.parse(json, LinkedList.<jk>class</jk>, LinkedList.<jk>class</jk>, String.<jk>class</jk>);
    *
    *    <jc>// Parse into a map of string keys/values.</jc>
    *    Map m = p.parse(json, TreeMap.<jk>class</jk>, String.<jk>class</jk>, String.<jk>class</jk>);
    *
    *    <jc>// Parse into a map containing string keys and values of lists containing beans.</jc>
    *    Map m = p.parse(json, TreeMap.<jk>class</jk>, String.<jk>class</jk>, List.<jk>class</jk>, MyBean.<jk>class</jk>);
    * </p>
    *
    * <p>
    * <c>Collection</c> classes are assumed to be followed by zero or one objects indicating the element type.
    *
    * <p>
    * <c>Map</c> classes are assumed to be followed by zero or two meta objects indicating the key and value types.
    *
    * <p>
    * The array can be arbitrarily long to indicate arbitrarily complex data structures.
    *
    * <ul class='notes'>
    *    <li>
    *       Use the {@link #parse(Object, Class)} method instead if you don't need a parameterized map/collection.
    * </ul>
    *
    * @param <T> The class type of the object to create.
    * @param input
    *    The input.
    *    <br>Character-based parsers can handle the following input class types:
    *    <ul>
    *       <li><jk>null</jk>
    *       <li>{@link Reader}
    *       <li>{@link CharSequence}
    *       <li>{@link InputStream} containing UTF-8 encoded text (or charset defined by
    *          {@link ReaderParser#RPARSER_streamCharset} property value).
    *       <li><code><jk>byte</jk>[]</code> containing UTF-8 encoded text (or charset defined by
    *          {@link ReaderParser#RPARSER_streamCharset} property value).
    *       <li>{@link File} containing system encoded text (or charset defined by
    *          {@link ReaderParser#RPARSER_fileCharset} property value).
    *    </ul>
    *    <br>Stream-based parsers can handle the following input class types:
    *    <ul>
    *       <li><jk>null</jk>
    *       <li>{@link InputStream}
    *       <li><code><jk>byte</jk>[]</code>
    *       <li>{@link File}
    *    </ul>
    * @param type
    *    The object type to create.
    *    <br>Can be any of the following: {@link ClassMeta}, {@link Class}, {@link ParameterizedType}, {@link GenericArrayType}
    * @param args
    *    The type arguments of the class if it's a collection or map.
    *    <br>Can be any of the following: {@link ClassMeta}, {@link Class}, {@link ParameterizedType}, {@link GenericArrayType}
    *    <br>Ignored if the main type is not a map or collection.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    * @see BeanSession#getClassMeta(Type,Type...) for argument syntax for maps and collections.
    * @throws IOException Thrown by the underlying stream.
    */
   @SuppressWarnings("unchecked")
   public final <T> T parse(Object input, Type type, Type...args) throws ParseException, IOException {
      try (ParserPipe pipe = createPipe(input)) {
         return (T)parseInner(pipe, getClassMeta(type, args));
      }
   }

   /**
    * Same as {@link #parse(Object,Type,Type...)} but parses from a string and doesn't throw an {@link IOException}.
    *
    * @param <T> The class type of the object to create.
    * @param input
    *    The input.
    *    <br>Character-based parsers can handle the following input class types:
    *    <ul>
    *       <li><jk>null</jk>
    *       <li>{@link Reader}
    *       <li>{@link CharSequence}
    *       <li>{@link InputStream} containing UTF-8 encoded text (or charset defined by
    *          {@link ReaderParser#RPARSER_streamCharset} property value).
    *       <li><code><jk>byte</jk>[]</code> containing UTF-8 encoded text (or charset defined by
    *          {@link ReaderParser#RPARSER_streamCharset} property value).
    *       <li>{@link File} containing system encoded text (or charset defined by
    *          {@link ReaderParser#RPARSER_fileCharset} property value).
    *    </ul>
    *    <br>Stream-based parsers can handle the following input class types:
    *    <ul>
    *       <li><jk>null</jk>
    *       <li>{@link InputStream}
    *       <li><code><jk>byte</jk>[]</code>
    *       <li>{@link File}
    *    </ul>
    * @param type
    *    The object type to create.
    *    <br>Can be any of the following: {@link ClassMeta}, {@link Class}, {@link ParameterizedType}, {@link GenericArrayType}
    * @param args
    *    The type arguments of the class if it's a collection or map.
    *    <br>Can be any of the following: {@link ClassMeta}, {@link Class}, {@link ParameterizedType}, {@link GenericArrayType}
    *    <br>Ignored if the main type is not a map or collection.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    * @see BeanSession#getClassMeta(Type,Type...) for argument syntax for maps and collections.
    */
   @SuppressWarnings("unchecked")
   public final <T> T parse(String input, Type type, Type...args) throws ParseException {
      try (ParserPipe pipe = createPipe(input)) {
         return (T)parseInner(pipe, getClassMeta(type, args));
      } catch (IOException e) {
         throw new ParseException(e); // Shouldn't happen.
      }
   }

   /**
    * Same as {@link #parse(Object, Type, Type...)} except optimized for a non-parameterized class.
    *
    * <p>
    * This is the preferred parse method for simple types since you don't need to cast the results.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bcode w800'>
    *    ReaderParser p = JsonParser.<jsf>DEFAULT</jsf>;
    *
    *    <jc>// Parse into a string.</jc>
    *    String s = p.parse(json, String.<jk>class</jk>);
    *
    *    <jc>// Parse into a bean.</jc>
    *    MyBean b = p.parse(json, MyBean.<jk>class</jk>);
    *
    *    <jc>// Parse into a bean array.</jc>
    *    MyBean[] ba = p.parse(json, MyBean[].<jk>class</jk>);
    *
    *    <jc>// Parse into a linked-list of objects.</jc>
    *    List l = p.parse(json, LinkedList.<jk>class</jk>);
    *
    *    <jc>// Parse into a map of object keys/values.</jc>
    *    Map m = p.parse(json, TreeMap.<jk>class</jk>);
    * </p>
    *
    * @param <T> The class type of the object being created.
    * @param input
    *    The input.
    *    See {@link #parse(Object, Type, Type...)} for details.
    * @param type The object type to create.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    * @throws IOException Thrown by the underlying stream.
    */
   public final <T> T parse(Object input, Class<T> type) throws ParseException, IOException {
      try (ParserPipe pipe = createPipe(input)) {
         return parseInner(pipe, getClassMeta(type));
      }
   }

   /**
    * Same as {@link #parse(Object, Class)} but parses from a string and doesn't throw an {@link IOException}.
    *
    * <p>
    * This is the preferred parse method for simple types since you don't need to cast the results.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bcode w800'>
    *    ReaderParser p = JsonParser.<jsf>DEFAULT</jsf>;
    *
    *    <jc>// Parse into a string.</jc>
    *    String s = p.parse(json, String.<jk>class</jk>);
    *
    *    <jc>// Parse into a bean.</jc>
    *    MyBean b = p.parse(json, MyBean.<jk>class</jk>);
    *
    *    <jc>// Parse into a bean array.</jc>
    *    MyBean[] ba = p.parse(json, MyBean[].<jk>class</jk>);
    *
    *    <jc>// Parse into a linked-list of objects.</jc>
    *    List l = p.parse(json, LinkedList.<jk>class</jk>);
    *
    *    <jc>// Parse into a map of object keys/values.</jc>
    *    Map m = p.parse(json, TreeMap.<jk>class</jk>);
    * </p>
    *
    * @param <T> The class type of the object being created.
    * @param input
    *    The input.
    *    See {@link #parse(Object, Type, Type...)} for details.
    * @param type The object type to create.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    */
   public final <T> T parse(String input, Class<T> type) throws ParseException {
      try (ParserPipe pipe = createPipe(input)) {
         return parseInner(pipe, getClassMeta(type));
      } catch (IOException e) {
         throw new ParseException(e); // Shouldn't happen.
      }
   }

   /**
    * Same as {@link #parse(Object, Type, Type...)} except the type has already been converted into a {@link ClassMeta}
    * object.
    *
    * <p>
    * This is mostly an internal method used by the framework.
    *
    * @param <T> The class type of the object being created.
    * @param input
    *    The input.
    *    See {@link #parse(Object, Type, Type...)} for details.
    * @param type The object type to create.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    * @throws IOException Thrown by the underlying stream.
    */
   public final <T> T parse(Object input, ClassMeta<T> type) throws ParseException, IOException {
      try (ParserPipe pipe = createPipe(input)) {
         return parseInner(pipe, type);
      }
   }

   /**
    * Same as {@link #parse(Object, ClassMeta)} except parses from a string and doesn't throw an {@link IOException}.
    *
    * <p>
    * This is mostly an internal method used by the framework.
    *
    * @param <T> The class type of the object being created.
    * @param input
    *    The input.
    *    See {@link #parse(Object, Type, Type...)} for details.
    * @param type The object type to create.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    */
   public final <T> T parse(String input, ClassMeta<T> type) throws ParseException {
      try (ParserPipe pipe = createPipe(input)) {
         return parseInner(pipe, type);
      } catch (IOException e) {
         throw new ParseException(e); // Shouldn't happen.
      }
   }

   /**
    * Entry point for all parsing calls.
    *
    * <p>
    * Calls the {@link #doParse(ParserPipe, ClassMeta)} implementation class and catches/re-wraps any exceptions
    * thrown.
    *
    * @param pipe The parser input.
    * @param type The class type of the object to create.
    * @param <T> The class type of the object to create.
    * @return The parsed object.
    * @throws ParseException Malformed input encountered.
    * @throws IOException Thrown by the underlying stream.
    */
   private <T> T parseInner(ParserPipe pipe, ClassMeta<T> type) throws ParseException, IOException {
      if (type.isVoid())
         return null;
      try {
         return doParse(pipe, type);
      } catch (ParseException | IOException e) {
         throw e;
      } catch (StackOverflowError e) {
         throw new ParseException(this, "Depth too deep.  Stack overflow occurred.");
      } catch (Exception e) {
         throw new ParseException(this, e, "Exception occurred.  exception={0}, message={1}.",
            e.getClass().getSimpleName(), e.getLocalizedMessage());
      } finally {
         checkForWarnings();
      }
   }

   /**
    * Parses the contents of the specified reader and loads the results into the specified map.
    *
    * <p>
    * Reader must contain something that serializes to a map (such as text containing a JSON object).
    *
    * <p>
    * Used in the following locations:
    * <ul class='spaced-list'>
    *    <li>
    *       The various character-based constructors in {@link OMap} (e.g.
    *       {@link OMap#OMap(CharSequence,Parser)}).
    * </ul>
    *
    * @param <K> The key class type.
    * @param <V> The value class type.
    * @param input The input.  See {@link #parse(Object, ClassMeta)} for supported input types.
    * @param m The map being loaded.
    * @param keyType The class type of the keys, or <jk>null</jk> to default to <code>String.<jk>class</jk></code>.
    * @param valueType The class type of the values, or <jk>null</jk> to default to whatever is being parsed.
    * @return The same map that was passed in to allow this method to be chained.
    * @throws ParseException Malformed input encountered.
    * @throws UnsupportedOperationException If not implemented.
    */
   public final <K,V> Map<K,V> parseIntoMap(Object input, Map<K,V> m, Type keyType, Type valueType) throws ParseException {
      try (ParserPipe pipe = createPipe(input)) {
         return doParseIntoMap(pipe, m, keyType, valueType);
      } catch (ParseException e) {
         throw e;
      } catch (Exception e) {
         throw new ParseException(this, e);
      } finally {
         checkForWarnings();
      }
   }

   /**
    * Implementation method.
    *
    * <p>
    * Default implementation throws an {@link UnsupportedOperationException}.
    *
    * @param pipe The parser input.
    * @param m The map being loaded.
    * @param keyType The class type of the keys, or <jk>null</jk> to default to <code>String.<jk>class</jk></code>.
    * @param valueType The class type of the values, or <jk>null</jk> to default to whatever is being parsed.
    * @return The same map that was passed in to allow this method to be chained.
    * @throws Exception If thrown from underlying stream, or if the input contains a syntax error or is malformed.
    */
   protected <K,V> Map<K,V> doParseIntoMap(ParserPipe pipe, Map<K,V> m, Type keyType, Type valueType) throws Exception {
      throw new UnsupportedOperationException("Parser '"+getClass().getName()+"' does not support this method.");
   }

   /**
    * Parses the contents of the specified reader and loads the results into the specified collection.
    *
    * <p>
    * Used in the following locations:
    * <ul class='spaced-list'>
    *    <li>
    *       The various character-based constructors in {@link OList} (e.g.
    *       {@link OList#OList(CharSequence,Parser)}.
    * </ul>
    *
    * @param <E> The element class type.
    * @param input The input.  See {@link #parse(Object, ClassMeta)} for supported input types.
    * @param c The collection being loaded.
    * @param elementType The class type of the elements, or <jk>null</jk> to default to whatever is being parsed.
    * @return The same collection that was passed in to allow this method to be chained.
    * @throws ParseException Malformed input encountered.
    * @throws UnsupportedOperationException If not implemented.
    */
   public final <E> Collection<E> parseIntoCollection(Object input, Collection<E> c, Type elementType) throws ParseException {
      try (ParserPipe pipe = createPipe(input)) {
         return doParseIntoCollection(pipe, c, elementType);
      } catch (ParseException e) {
         throw e;
      } catch (StackOverflowError e) {
         throw new ParseException(this, "Depth too deep.  Stack overflow occurred.");
      } catch (IOException e) {
         throw new ParseException(this, e, "I/O exception occurred.  exception={0}, message={1}.",
            e.getClass().getSimpleName(), e.getLocalizedMessage());
      } catch (Exception e) {
         throw new ParseException(this, e, "Exception occurred.  exception={0}, message={1}.",
            e.getClass().getSimpleName(), e.getLocalizedMessage());
      } finally {
         checkForWarnings();
      }
   }

   /**
    * Implementation method.
    *
    * <p>
    * Default implementation throws an {@link UnsupportedOperationException}.
    *
    * @param pipe The parser input.
    * @param c The collection being loaded.
    * @param elementType The class type of the elements, or <jk>null</jk> to default to whatever is being parsed.
    * @return The same collection that was passed in to allow this method to be chained.
    * @throws Exception If thrown from underlying stream, or if the input contains a syntax error or is malformed.
    */
   protected <E> Collection<E> doParseIntoCollection(ParserPipe pipe, Collection<E> c, Type elementType) throws Exception {
      throw new UnsupportedOperationException("Parser '"+getClass().getName()+"' does not support this method.");
   }

   /**
    * Parses the specified array input with each entry in the object defined by the {@code argTypes}
    * argument.
    *
    * <p>
    * Used for converting arrays (e.g. <js>"[arg1,arg2,...]"</js>) into an {@code Object[]} that can be passed
    * to the {@code Method.invoke(target, args)} method.
    *
    * <p>
    * Used in the following locations:
    * <ul class='spaced-list'>
    *    <li>
    *       Used to parse argument strings in the {@link PojoIntrospector#invokeMethod(Method, Reader)} method.
    * </ul>
    *
    * @param input The input.  Subclasses can support different input types.
    * @param argTypes Specifies the type of objects to create for each entry in the array.
    * @return An array of parsed objects.
    * @throws ParseException Malformed input encountered.
    */
   public final Object[] parseArgs(Object input, Type[] argTypes) throws ParseException {
      try (ParserPipe pipe = createPipe(input)) {
         return doParse(pipe, getArgsClassMeta(argTypes));
      } catch (ParseException e) {
         throw e;
      } catch (StackOverflowError e) {
         throw new ParseException(this, "Depth too deep.  Stack overflow occurred.");
      } catch (IOException e) {
         throw new ParseException(this, e, "I/O exception occurred.  exception={0}, message={1}.",
            e.getClass().getSimpleName(), e.getLocalizedMessage());
      } catch (Exception e) {
         throw new ParseException(this, e, "Exception occurred.  exception={0}, message={1}.",
            e.getClass().getSimpleName(), e.getLocalizedMessage());
      } finally {
         checkForWarnings();
      }
   }

   /**
    * Converts the specified string to the specified type.
    *
    * @param outer
    *    The outer object if we're converting to an inner object that needs to be created within the context
    *    of an outer object.
    * @param s The string to convert.
    * @param type The class type to convert the string to.
    * @return The string converted as an object of the specified type.
    * @param <T> The class type to convert the string to.
    * @throws IOException Thrown by underlying stream.
    * @throws ParseException Malformed input encountered.
    * @throws ExecutableException Exception occurred on invoked constructor/method/field.
    */
   @SuppressWarnings({ "unchecked", "rawtypes" })
   protected final <T> T convertAttrToType(Object outer, String s, ClassMeta<T> type) throws IOException, ParseException, ExecutableException {
      if (s == null)
         return null;

      if (type == null)
         type = (ClassMeta<T>)object();
      PojoSwap swap = type.getSwap(this);
      ClassMeta<?> sType = swap == null ? type : swap.getSwapClassMeta(this);

      Object o = s;
      if (sType.isChar())
         o = parseCharacter(s);
      else if (sType.isNumber())
         o = parseNumber(s, (Class<? extends Number>)sType.getInnerClass());
      else if (sType.isBoolean())
         o = Boolean.parseBoolean(s);
      else if (! (sType.isCharSequence() || sType.isObject())) {
         if (sType.canCreateNewInstanceFromString(outer))
            o = sType.newInstanceFromString(outer, s);
         else
            throw new ParseException(this, "Invalid conversion from string to class ''{0}''", type);
      }

      if (swap != null)
         o = unswap(swap, o, type);

      return (T)o;
   }

   /**
    * Convenience method for calling the {@link ParentProperty @ParentProperty} method on the specified object if it
    * exists.
    *
    * @param cm The class type of the object.
    * @param o The object.
    * @param parent The parent to set.
    * @throws ExecutableException Exception occurred on invoked constructor/method/field.
    */
   protected static final void setParent(ClassMeta<?> cm, Object o, Object parent) throws ExecutableException {
      Setter m = cm.getParentProperty();
      if (m != null)
         m.set(o, parent);
   }

   /**
    * Convenience method for calling the {@link NameProperty @NameProperty} method on the specified object if it exists.
    *
    * @param cm The class type of the object.
    * @param o The object.
    * @param name The name to set.
    * @throws ExecutableException Exception occurred on invoked constructor/method/field.
    */
   protected static final void setName(ClassMeta<?> cm, Object o, Object name) throws ExecutableException {
      if (cm != null) {
         Setter m = cm.getNameProperty();
         if (m != null)
            m.set(o, name);
      }
   }

   /**
    * Returns the listener associated with this session.
    *
    * @param c The listener class to cast to.
    * @return The listener associated with this session, or <jk>null</jk> if there is no listener.
    */
   @SuppressWarnings("unchecked")
   public <T extends ParserListener> T getListener(Class<T> c) {
      return (T)listener;
   }

   /**
    * The {@link #createPipe(Object)} method should call this method to set the pipe for debugging purposes.
    *
    * @param pipe The pipe created for this session.
    * @return The same pipe.
    */
   protected ParserPipe setPipe(ParserPipe pipe) {
      this.pipe = pipe;
      return pipe;
   }

   /**
    * Returns the current position into the reader or input stream.
    *
    * @return
    *    The current position into the reader or input stream.
    *    <br>Never <jk>null</jk>.
    */
   public Position getPosition() {
      if (mark.line != -1 || mark.column != -1 || mark.position != -1)
         return mark;
      if (pipe == null)
         return Position.UNKNOWN;
      return pipe.getPosition();
   }

   /**
    * Marks the current position.
    */
   protected void mark() {
      if (pipe != null) {
         Position p = pipe.getPosition();
         mark.line = p.line;
         mark.column = p.column;
         mark.position = p.position;
      }
   }

   /**
    * Unmarks the current position.
    */
   protected void unmark() {
      mark.line = -1;
      mark.column = -1;
      mark.position = -1;
   }

   /**
    * Returns the input as a string.
    *
    * <p>
    * This always returns a value for input of type {@link CharSequence}.
    * <br>For other input types, use {@link Context#CONTEXT_debug} setting to enable caching to a string
    * before parsing so that this method returns the input.
    *
    * @return The input as a string, or <jk>null</jk> if no pipe has been created or we're reading from an uncached reader or input stream source.
    */
   public String getInputAsString() {
      return pipe == null ? null : pipe.getInputAsString();
   }

   /**
    * Invokes the specified swap on the specified object.
    *
    * @param swap The swap to invoke.
    * @param o The input object.
    * @param eType The expected type.
    * @return The swapped object.
    * @throws ParseException If swap method threw an exception.
    */
   @SuppressWarnings({ "rawtypes", "unchecked" })
   protected Object unswap(PojoSwap swap, Object o, ClassMeta<?> eType) throws ParseException {
      try {
         return swap.unswap(this, o, eType);
      } catch (Exception e) {
         throw new ParseException(e);
      }
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Properties
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Configuration property:  Auto-close streams.
    *
    * @see Parser#PARSER_autoCloseStreams
    * @return
    *    <jk>true</jk> if <l>InputStreams</l> and <l>Readers</l> passed into parsers will be closed
    *    after parsing is complete.
    */
   protected final boolean isAutoCloseStreams() {
      return ctx.isAutoCloseStreams();
   }

   /**
    * Configuration property:  Debug output lines.
    *
    * @see Parser#PARSER_debugOutputLines
    * @return
    *    The number of lines of input before and after the error location to be printed as part of the exception message.
    */
   protected final int getDebugOutputLines() {
      return ctx.getDebugOutputLines();
   }

   /**
    * Returns the listener associated with this session.
    *
    * @return The listener associated with this session, or <jk>null</jk> if there is no listener.
    */
   public ParserListener getListener() {
      return listener;
   }

   /**
    * Configuration property:  Strict mode.
    *
    * @see Parser#PARSER_strict
    * @return
    *    <jk>true</jk> if strict mode for the parser is enabled.
    */
   protected final boolean isStrict() {
      return ctx.isStrict();
   }

   /**
    * Configuration property:  Trim parsed strings.
    *
    * @see Parser#PARSER_trimStrings
    * @return
    *    <jk>true</jk> if string values will be trimmed of whitespace using {@link String#trim()} before being added to
    *    the POJO.
    */
   protected final boolean isTrimStrings() {
      return ctx.isTrimStrings();
   }

   /**
    * Configuration property:  Unbuffered.
    *
    * @see Parser#PARSER_unbuffered
    * @return
    *    <jk>true</jk> if parsers don't use internal buffering during parsing.
    */
   protected final boolean isUnbuffered() {
      return ctx.isUnbuffered();
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Other methods
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Configuration property:  Parser listener.
    *
    * @see Parser#PARSER_listener
    * @return
    *    Class used to listen for errors and warnings that occur during parsing.
    */
   protected final Class<? extends ParserListener> getListenerClass() {
      return ctx.getListener();
   }

   @Override /* Session */
   public OMap toMap() {
      return super.toMap()
         .a("ParserSession", new DefaultFilteringOMap()
            .a("javaMethod", javaMethod)
            .a("listener", listener)
            .a("outer", outer)
         );
   }
}