# logical.java

    /*
    ** Module   : logical.java
    ** Abstract : Progress 4GL compatible logical object
    **
    ** Copyright (c) 2005-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ----------------------------------Description----------------------------------
    ** 001 GES 20050517   @21233 Created initial version with full support
    **                           for all Progress logical processing including
    **                           all operators (AND, OR and NOT are in this
    **                           class and all others in the parent class)
    **                           and the unknown value.
    ** 002 GES 20050607   @21444 Minor additions for function support.
    ** 003 GES 20050621   @21534 Added an assign() method to modify this
    **                           instance's state based on the result of
    **                           an expression of compatible type.
    ** 004 GES 20050721   @21765 Added a constructor that takes a string and
    **                           merged cloning for SVG.
    ** 005 GES 20050815   @22120 Added Undoable interface support.
    ** 006 GES 20050830   @22385 Added error condition processing.
    ** 007 ECF 20051004   @22971 Implement hashCode() method. Required to be
    **                           consistent with BaseDataType's implementation
    **                           of equals() method.
    ** 008 GES 20051022   @23088 Handle the case of an OR operator with both
    **                           operands as unknown.
    ** 009 GES 20060206   @24302 Made compareTo() safe to process any object
    **                           type (avoids ClassCastException).
    ** 010 GES 20060208   @24391 Added a default format string getter and
    **                           a new constructor that uses a format string
    **                           to parse out a string value properly.
    ** 011 GES 20060312   @24987 Added variants of the OR, AND and NOT
    **                           operators to allow primitives to be passed
    **                           in all possible combinations.
    ** 012 GES 20060417   @25556 Added default value generation.
    ** 013 GES 20060518   @26347 "/" is an invalid format string too.
    ** 014 GES 20060522   @26387 Added forms of the OR and AND operators which
    **                           defer the processing of the right by passing
    **                           a LogicalExpression instance which is only
    **                           evaluated conditionally.  This is needed
    **                           to ensure that right operand conditions that
    **                           have side effects or can generate an error
    **                           will not process if the left operand is
    **                           enough to make a decision.
    ** 015 GES 20060616   @27357 OR and AND operators had unknown value
    **                           processing reversed from what it should have
    **                           been (the logic was mis-documented originally
    **                           and was implemented as mis-documented). This
    **                           has been resolved.
    ** 016 GES 20060724   @28163 Added a forced assign() abstract method.
    ** 017 GES 20060807   @28475 Moved to externalizable interface to optimize
    **                           network performance.
    ** 018 ECF 20060812   @28589 Added methods needed for database server-side
    **                           function support.
    ** 019 NVS 20060908   @28589 compareTo now properly compares with String
    **                           character type data.
    ** 020 GES 20061109   @31051 Added formatLength().
    ** 021 GES 20080624   @38913 Safer and more complete version of H019.
    ** 022 SIY 20080721   @39150 Fixed toString() behavior in order to match
    **                           4GL behavior in various situations.
    ** 023 GES 20080911   @39791 Added assign(boolean) signature.
    ** 024 GES 20081001   @40035 Modified method names to shorten calling
    **                           code for the logical operators.
    ** 025 ECF 20090212   @41301 Implemented a faster equals(). Handles most
    **                           common cases without having to invoke the
    **                           superclass' implementation.
    ** 026 GES 20090422   @41910 Converted to standard string formatting.
    ** 027 ECF 20090816   @43664 Removed final modifier from class.
    ** 028 GES 20090828   @43803 Make sure that ignore mode is disabled even if
    **                           and exception occurs.
    ** 029 GES 20110303          Moved maximum/minimum to varargs.
    ** 030 CA  20130123          Added c'tor which builds a new instance from a
    **                           BaseDataType value, if possible. This should be
    **                           used only when constructing an instance using the
    **                           value returned by a DYNAMIC-FUNCTION call; 4GL
    **                           does some special casting in this case, which is
    **                           not implemented yet.
    ** 031 GES 20130312          Implemented the BDT constructor. We hope it is suitable
    **                           for any _POLY that returns a BDT which is supposed to
    **                           be a logical.
    ** 032 GES 20130322          Fixed the BDT c'tor and modified the assign(BDT,boolean) to be the
    **                           common location for the _POLY morphing. This is safe because all
    **                           current usage would have generated a ClassCastException if that
    **                           method was ever used with an invalid type. Now, instead of the CCE,
    **                           the code will morph the value as is possible. The morphing code
    **                           still needs to be checked.
    ** 033 MAG 20140602          Fixed the BDT c'tor and modified the assign(BDT, boolean) on _POLY
    **                           morphing. Add BDT types on compareTo(Object).
    **                           Improve compareTo(Object) by comparing unknown values.
    ** 034 CA  20150310          Fixed initialization of logical values from a string.
    ** 035 OM  20150630          Documented char-to-logical conversion quirk.
    ** 036 CA  20151222          Added instantiateDefaultExtent.
    ** 037 EVL 20160224          Javadoc fixes to make compatible with Oracle Java 8 for Solaris 10.
    ** 038 GES 20160309          Fixed fromString() to match new undocumented 4GL cases.
    ** 039 OM  20160302          Fixed logical(boolean) constructor.
    ** 040 GES 20160518          Switched from LogicalExpression anon instances to LogicalOp lambdas
    **                           for AND and OR operator deferred evaluation.
    ** 041 GES 20160617          Added unknown literal processing for the polymorphic assign case.
    ** 042 CA  20160627          Reworked undoable support - the undoables register themselves with
    **                           all blocks up the stack, until either 1. the tx block which created
    **                           it is reached or 2. the last tx block where it was saved is reached.
    ** 043 GES 20171206          Changes in ErrorManager make silent error mode support unnecessary.
    ** 044 CA  20180514          Added logical(character, character) c'tor.
    ** 045 OM  20190206          Added implementation of field size needed by record-length.
    ** 046 CA  20190927          Added support for direct Java access from 4GL code.
    ** 047 RFB 20200804          _and() was evaluating the 2nd operator, instead of letting it flow to the and()
    **                           method. This was causing issues if the 2nd operator was unnecessary, and would
    **                           have side-effect results, like subscript out-of-range.
    **     GES 20200806          Reduced ErrorManager context-local usage.
    **     ME  20200810          Improvements to string parsing.
    **     EVL 20200818          Fix for value creation issue from empty string for custom format case that
    **                           considers empty string as valid false logical.
    **     GES 20200820          Fix for fromString() "trash matching" mode and slight performance improvement.
    ** 048 IAS 20201007          Added Type enum
    ** 049 VVT 20210403          splitFormat() fixed: only one slash character is allowed. See #4880-67.
    **     VVT 20210322          Fixed after the review. See #4880-107.
    ** 050 ME  20210504          Added isIncompatibleTypesOnConversion override for invalid POLY conversion.
    **     CA  20210923          Fixed logical(BDT, fmt) builtin function.
    **     OM  20220303          Renamed defaultFormat to DEFAULT_FORMAT and granted public access.
    **                           General code maintenance.
    **     AL2 20220319          Added value proxy check in assign.
    ** 051 CA  20230215          'duplicate()' method returns the real type instead of BDT.
    ** 052 CA  20231129          Avoid additional BDT creation for some operators which receive Java arguments.
    ** 053 CA  20240313          Converting a string to logical must not raise an error or set the
    **                           ERROR-STATUS:FLAG if the value does not match the format.
    ** 054 CA  20240320          Avoid BDTs within internal FWD runtime.  Replaced iterators with Java 'for',
    **                           where it applies.
    ** 055 CA  20240324          Use logical constants for TRUE, FALSE, UNKNOWN, within internal FWD runtime.
    **     CA  20240331          logical type checks must include sub-classes, too.
    ** 056 SP  20240415          Fixed assign(boolean): added missing checkUndoable().
    */

    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.util;

    import java.io.*;
    import java.math.*;
    import java.util.*;
    import java.util.function.*;

    /**
     * A class that represents a Progress 4GL compatible logical object whose
     * data is mutable.  All Progress language features related to logical
     * types are supported including all function that can be accessed via the
     * logical operators.  In particular, the <code>AND</code>, <code>OR</code>
     * and <code>NOT</code> operators are implemented in this class (they are
     * unique to logicals) and all other logical operators are implemented in
     * the {@link CompareOps} class.
     * <p>
     * The only reason this class exists is to provide an object that represents
     * 3 possible states: <code>true</code>, <code>false</code> and the
     * <code>unknown value</code>.  This is the only difference between the
     * Progress 4GL logical data type and the Java primitive <code>boolean</code>.
     * While a <code>java.lang.Boolean</code> could be used and set to
     * <code>null</code> to indicate the <code>unknown value</code>, this
     * approach has the significant drawback of requiring unwrapping everywhere
     * and in addition, <code>null</code> checks are required wherever the
     * data is unwrapped.  This would require a very nasty bit of refactoring for
     * most expressions, which is made unnecessary by this class which represents
     * the tri-state of a logical using only internal means.  Since all operators
     * have been implemented as method calls and these methods are aware of the
     * <code>unknown value</code>, the resulting expressions are clean and
     * as close to the original level of expressiveness as possible.
     * <p>
     * Format string related processing is handled in this class, see method
     * {@link #toString(String)}.
     * <p>
     * The following is the mapping of Progress language features to the
     * corresponding feature in this class:
     * <p>
     * <pre>
     * not      operator                       {@link #not} and {@link #_not}
     * and      operator                       {@link #and} and {@link #_and}
     * or       operator                       {@link #or} and {@link #_or}
     * =  or EQ operator                       {@link CompareOps#isEqual}
     * &lt;&gt; or NE operator                       {@link CompareOps#isNotEqual}
     * &gt;  or GT operator                       {@link CompareOps#isGreaterThan}
     * &gt;= or GE operator                       {@link CompareOps#isGreaterThanOrEqual}
     * &lt;  or LT operator                       {@link CompareOps#isLessThan}
     * &lt;= or LE operator                       {@link CompareOps#isLessThanOrEqual}
     * maximum  function                       {@link CompareOps#maximum(BaseDataType[])}
     * minimum  function                       {@link CompareOps#minimum(BaseDataType[])}
     * </pre>
     * <p>
     * <pre>
     *     OR Operator Truth Table
     *
     *   Left       Right     Result
     * ---------  ---------  ---------
     * true       true       true
     * false      true       true
     * unknown    true       true
     * true       false      true
     * false      false      false
     * unknown    false      unknown
     * true       unknown    true
     * false      unknown    unknown
     * unknown    unknown    unknown
     * </pre>
     * <p>
     * <pre>
     *    AND Operator Truth Table
     *
     *   Left       Right     Result
     * ---------  ---------  ---------
     * true       true       true
     * false      true       false
     * unknown    true       unknown
     * true       false      false
     * false      false      false
     * unknown    false      false
     * true       unknown    unknown
     * false      unknown    false
     * unknown    unknown    unknown
     * </pre>
     * <p>
     * <pre>
     *    NOT Operator Truth Table
     *
     *  Operand    Result
     * ---------  ---------
     * true       false
     * false      true
     * unknown    unknown
     * </pre>
     * <p>
     * There are convenience versions of each operator that directly return
     * <code>boolean</code> values such that unwrapping is not needed.  These
     * are named the same as the operator methods above except there is no
     * 'Operator' appended.  For example, the not operator is {@link #not}.
     *
     * @author    GES
     */
    public class logical
    extends BaseDataType
    {
       /** Singleton and immutable for the logical TRUE value. */
       public static final logical TRUE = new logicalConstant(true);

       /** Singleton and immutable for the logical FALSE value. */
       public static final logical FALSE = new logicalConstant(false);

       /** Singleton and immutable for the logical UNKNOWN value. */
       public static final logical UNKNOWN = new logicalConstant();

       /** The default format string. */
       public static final String DEFAULT_FORMAT = "yes/no";

       /**
        * Stores the state of this logical as <code>true</code> or
        * <code>false</code>, independent of the state of whether or not this
        * instance represents the <code>unknown value</code>.
        */
       private boolean value = false;

       /**
        * Stores the state of whether or not this instance represents the
        * <code>unknown value</code>, independent of the state of this logical's
        * value as <code>true</code> or <code>false</code>.
        */
       private boolean unknown = false;

       /**
        * Default constructor, creates an instance that represents the unknown
        * value.
        */
       public logical()
       {
          unknown = true;
       }

       /**
        * This is a special c'tor which should be used only when converting the
        * value returned by a function or method with polymorphic return type into the
        * expected type (i.e. DYNAMIC-FUNCTION()).  In such cases, the 4GL does some
        * automatic type conversion (see {@link #assign(BaseDataType)}).
        *
        * @param    value
        *           The value to be used for this instance.
        */
       public logical(BaseDataType value)
       {
          if (value == null || value.isUnknown())
          {
             setUnknown();
          }
          else
          {
             assign(value);
          }
       }

       /**
        * This is a special c'tor which should be used only when converting the
        * value returned by a function or method with polymorphic return type into the
        * expected type (i.e. DYNAMIC-FUNCTION()).  In such cases, the 4GL does some
        * automatic type conversion (see {@link #assign(BaseDataType)}).
        *
        * @param    value
        *           The value to be used for this instance.
        * @param    fmt
        *           The format string to use.
        */
       public logical(BaseDataType value, character fmt)
       {
          if (value == null || value.isUnknown() || fmt.isUnknown())
          {
             setUnknown();
          }
          else if (value instanceof Text)
          {
             assign(new logical(((Text) value).getValue(), fmt.toStringMessage()));
          }
          else
          {
             assign(value);
          }
       }

       /**
        * This is a special c'tor which should be used only when converting the
        * value returned by a function or method with polymorphic return type into the
        * expected type (i.e. DYNAMIC-FUNCTION()).  In such cases, the 4GL does some
        * automatic type conversion (see {@link #assign(BaseDataType)}).
        *
        * @param    value
        *           The value to be used for this instance.
        * @param    fmt
        *           The format string to use.
        */
       public logical(BaseDataType value, String fmt)
       {
          if (value == null || value.isUnknown() || fmt == null)
          {
             setUnknown();
          }
          else if (value instanceof Text)
          {
             assign(new logical(((Text) value).getValue(), fmt));
          }
          else
          {
             assign(value);
          }
       }

       /**
        * Constructs an instance that has the <code>boolean</code> value passed
        * in and which <b>does not</b> represent the <code>unknown value</code>.
        *
        * @param    value
        *           The logical value of the resulting instance.
        */
       public logical(boolean value)
       {
          this.value = value;
       }

       /**
        * Constructs an instance that has the <code>boolean</code> value and
        * <code>unknown value</code> that exactly matches that of the passed-in
        * instance.
        *
        * @param    value
        *           The logical and unknown value of the resulting instance.
        */
       public logical(logical value)
       {
          assign(value);
       }

       /**
        * Converts the given string into a logical value. A '?' is interpreted as
        * the <code>unknown value</code> and the strings 'yes' and 'true' (and
        * any abbreviations thereof) are considered <code>true</code> and
        * any other input is considered <code>false</code>.
        *
        * @param    value
        *           The text representation of the logical value.
        */
       public logical(String value)
       {
          this(value, DEFAULT_FORMAT);
       }

       /**
        * Converts the given string into a logical value. A '?' is interpreted as
        * the <code>unknown value</code> and the strings 'yes' and 'true' (and
        * any abbreviations thereof) are considered <code>true</code> and
        * any other input is considered <code>false</code>.
        *
        * @param    value
        *           The text representation of the logical value.
        */
       public logical(character value)
       {
          this(value, DEFAULT_FORMAT);
       }

       /**
        * Converts the given string into a logical value. A '?' is interpreted as
        * the <code>unknown value</code> and the strings 'yes' and 'true' (and
        * any abbreviations thereof) are considered <code>true</code> and
        * any other input is considered <code>false</code>.
        * <p>
        * Parses the string using default formats 'yes/no' and 'true/false' and
        * the passed in format string. Any any abbreviations of the above formats
        * are also considered as a match.
        *
        * TODO: when a LOGICAL argument is passed as OUTPUT parameter to a procedure the implicit
        *       conversion will fails without reason. The following message is displayed:
        *       [** Input value:  should be yes/no. (87)]
        *       When the argument is passes to a INPUT-OUTPUT parameter, everything is fine.
        *
        * @param    value
        *           The text representation of the logical value.
        * @param    fmt
        *           The format string to use.
        */
       public logical(character value, String fmt)
       {
          if (value.isUnknown())
          {
             setUnknown();
          }
          else
          {
             assign(new logical(value.getValue(), fmt));
          }
       }

       /**
        * Converts the given string into a logical value. A '?' is interpreted as
        * the <code>unknown value</code> and the strings 'yes' and 'true' (and
        * any abbreviations thereof) are considered <code>true</code> and
        * any other input is considered <code>false</code>.
        * <p>
        * Parses the string using default formats 'yes/no' and 'true/false' and
        * the passed in format string. Any any abbreviations of the above formats
        * are also considered as a match.
        *
        * TODO: when a LOGICAL argument is passed as OUTPUT parameter to a procedure the implicit
        *       conversion will fails without reason. The following message is displayed:
        *       [** Input value:  should be yes/no. (87)]
        *       When the argument is passes to a INPUT-OUTPUT parameter, everything is fine.
        *
        * @param    value
        *           The text representation of the logical value.
        * @param    fmt
        *           The format string to use.
        */
       public logical(character value, character fmt)
       {
          if (value.isUnknown() || fmt.isUnknown())
          {
             setUnknown();
          }
          else
          {
             assign(new logical(value.getValue(), fmt.toStringMessage()));
          }
       }

       /**
        * Converts the given string into a logical value. A '?' is interpreted as
        * the <code>unknown value</code>.  Parses the string using default
        * formats 'yes/no' and 'true/false' and the passed in format string. Any
        * any abbreviations of the above formats are also considered as a match.
        *
        * @param    value
        *           The text representation of the logical value.
        * @param    fmt
        *           The format string to use.
        *
        * @throws   ErrorConditionException
        *           If no match is found.
        */
       public logical(String value, String fmt)
       throws ErrorConditionException
       {
          if (value == null || value.equals("?"))
          {
             setUnknown();
          }
          else
          {
             Boolean res = fromString(value, fmt);

             if (res == null)
             {
                String errmsg = "Input value: " + value + " should be " + fmt;
                ErrorManager.recordOrShowError(87, errmsg, true, true, false, false);

                setUnknown();
             }
             else
             {
                this.value = res;
             }
          }
       }

       /**
        * Constructs an instance after copying the parameter's data into the
        * internal representation of this class.
        * <p>
        * If the parameter is <code>null</code>, this instance will represent
        * the <code>unknown value</code>.
        *
        * @param   value
        *          The value to be used for this instance.
        */
       public logical(Boolean value)
       {
          if (value == null)
          {
             setUnknown();
          }
          else
          {
             this.value = value;
          }
       }

       /**
        * Resolve the given boolean value to a logical TRUE/FALSE singleton.
        * <p>
        * WARNING: this must be used only from within the fwd runtime or as an instance returned to the converted
        * code, to be assigned to a mutable instance.  The return instance is immutable!
        *
        * @param    value
        *           The value to resolve
        *
        * @return   See above.
        */
       public static logical of(boolean value)
       {
          return value ? logical.TRUE : logical.FALSE;
       }

       /**
        * Check if the given value matches the received format.  This method is called at runtime
        * (from this class' constructor) or at conversion time (used for "boolean manhandling").
        * <p>
        * The default formats of "yes/no" and "true/false" are always considered and will match
        * in preference to an explicitly provided format string. This means that any conflict with
        * the explicitly provided format string will match one of the default formats first (in
        * preference).
        * <p>
        * Matching is done on a case-insensitive basis.
        * <p>
        * Interestingly, any matching subset of valid match text will match.  This means that an
        * exact match or an unambiguous abbreviated match to a format string of the form 'XXX/YYY'
        * will make x, X, xx, XX, xxx, XXX all resolve to <code>true</code> and y, Y, yy, YY, yyy,
        * YYY all resolve to <code>false</code>.  This optional abbreviation support works for
        * matches to both the default formats AND to explicitly provided custom formats.
        * <p>
        * The default formats have an additional "trash matching" behavior. When specifying yes, no,
        * true or false, the string can contain any trash so long as the trash is following a space
        * character.  This means a <code>yes   . bogus text.</code> matches a <code>yes</code> in a
        * default format. This same ridiculous trick does not work for explicit custom formats.
        * <p>
        * All of the above behavior is indeed how the 4GL does it.  No, it doesn't make any sense.
        * <p>
        * At conversion time, all enclosing quote characters should already have been removed from
        * both input parameters.  It is expected that this is always already the case with runtime
        * strings.
        *
        * @param    val
        *           The value to be checked.
        * @param    fmt
        *           The format; if <code>null</code>, the {@link #DEFAULT_FORMAT} will be used.
        *
        * @return   <code>null</code> if the value does not match the format.  Otherwise, the value's
        *           <code>true</code> or <code>false</code> state.
        */
       public static Boolean fromString(String val, String fmt)
       {
          // the val can be empty if the custom format case considers this option as valid boolean
          if (val == null || (val.isEmpty() && (fmt == null || (!fmt.startsWith("/") && !fmt.endsWith("/")))))
          {
             return null;
          }

          List<String> list = new ArrayList<>();

          // custom format is checked first (might be invalid, #errno 74)
          if (fmt != null)
          {
             fmt = fmt.toLowerCase();
             list.add(fmt);
          }

          if (fmt == null || !fmt.equals(DEFAULT_FORMAT))
          {
             list.add(DEFAULT_FORMAT);
          }

          if (fmt == null || !fmt.equals("true/false"))
          {
             list.add("true/false");
          }

          String[] fmts   = list.toArray(new String[0]);
          String   target = val.toLowerCase();

          for (int i = 0; i < fmts.length; i++)
          {
             String current  = fmts[i];
             String[] values = splitFormat(current);
             String yesVal   = values[0];
             String noVal    = values[1];

             // check 1: exact or unambiguous subset match
             if (target.isEmpty())
             {
                // in custom format case the target can be empty
                // for this  case one of the custom option should be empty too
                if (yesVal.isEmpty())
                {
                   return true;
                }
                else if (noVal.isEmpty())
                {
                   return false;
                }
             }
             else
             {
                if (yesVal.startsWith(target))
                {
                   return true;
                }
                else if (noVal.startsWith(target))
                {
                   return false;
                }
             }

             // default formats only, try trash matching mode
             if (fmt == null || fmts.length == 2 || i > 0)
             {
                // check 2: if not explicit format, first token in target (using space as separator)
                // must be a yesVal or noVal. any other tokens after this one are discarded/ignored
                if (target.startsWith(yesVal + " "))
                {
                   return true;
                }
                else if (target.startsWith(noVal + " "))
                {
                   return false;
                }
             }
          }

          return null;
       }

       /**
        * Get the type
        * @return type
        */
       public Type getType()
       {
          return Type.LOGICAL;
       }

       /**
        * Returns the largest instance (<code>false</code> is smaller than
        * <code>true</code>) from the list.  This list may not include
        * <code>null</code> values.
        *
        * @param    list
        *           The list of logicals to check.
        *
        * @return   The largest instance or <code>unknown value</code> if any
        *           entries in the list are unknown or <code>null</code> if
        *           an empty list is passed.
        */
       public static logical maximum(logical ... list)
       {
          return (logical) CompareOps.maximum(list);
       }

       /**
        * Returns the smallest instance (<code>false</code> is smaller than
        * <code>true</code>) from the list.  This list may not include
        * <code>null</code> values.
        *
        * @param    list
        *           The list of decimals to check.
        *
        * @return   The smallest instance or <code>unknown value</code> if any
        *           entries in the list are unknown or <code>null</code> if
        *           an empty list is passed.
        */
       public static logical minimum(logical ... list)
       {
          return (logical) CompareOps.minimum(list);
       }

       /**
        * Implements the <code>NOT</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        *
        * @param    op
        *           The operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _not(logical op)
       {
          return op.unknown ? false : !op.value;
       }

       /**
        * Implements the <code>NOT</code> logical operator using the Java logical
        * NOT.
        *
        * @param    op
        *           The operand.
        *
        * @return   The result of the operator.
        */
       public static logical not(boolean op)
       {
          return logical.of(!op);
       }

       /**
        * Implements the <code>NOT</code> logical operator with proper processing
        * of the <code>unknown value</code>.  In particular, if the operand
        * is unknown, then <code>unknown value</code> is returned.
        * <p>
        * If the operand is not <code>unknown</code>, the boolean value will
        * be negated and returned using the Java logical NOT.
        *
        * @param    op
        *           The operand.
        *
        * @return   The result of the operator.
        */
       public static logical not(logical op)
       {
          if (op.unknown)
             return (logical) logical.UNKNOWN;

          return logical.of(!(op.value));
       }

       /**
        * Implements the <code>AND</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _and(boolean op1, boolean op2)
       {
          return op1 && op2;
       }

       /**
        * Implements the <code>AND</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _and(logical op1, boolean op2)
       {
          return op2 && !op1.unknown && op1.value;
       }

       /**
        * Implements the <code>AND</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _and(boolean op1, logical op2)
       {
          return op1 && !op2.unknown && op2.value;
       }

       /**
        * Implements the <code>AND</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _and(logical op1, logical op2)
       {
          return !op1.unknown && !op2.unknown && op1.value && op2.value;
       }

       /**
        * Implements the <code>AND</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _and(boolean op1, LogicalOp op2)
       {
          return op1 && _and(op1, op2.evaluate());
       }

       /**
        * Implements the <code>AND</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _and(logical op1, LogicalOp op2)
       {
          return !op1.unknown && op1.value && _and(op1, op2.evaluate());
       }

       /**
        * Implements the <code>AND</code> logical operator (just a convenience
        * method for the Java logical AND).
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical and(boolean op1, boolean op2)
       {
          return logical.of(op1 && op2);
       }

       /**
        * Implements the <code>AND</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>true</code> and
        * <code>false</code> is returned if the other operand is
        * <code>false</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical AND.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical and(boolean op1, logical op2)
       {
          return and(logical.of(op1), op2);
       }

       /**
        * Implements the <code>AND</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>true</code> and
        * <code>false</code> is returned if the other operand is
        * <code>false</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical AND.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical and(logical op1, boolean op2)
       {
          return and(op1, logical.of(op2));
       }

       /**
        * Implements the <code>AND</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>true</code> and
        * <code>false</code> is returned if the other operand is
        * <code>false</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical AND.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical and(logical op1, logical op2)
       {
          if (op1.unknown && op2.unknown)
          {
             return logical.UNKNOWN;
          }

          if (op1.unknown && !op2.unknown)
          {
             return op2.value ? logical.UNKNOWN : logical.of(false);
          }

          if (!op1.unknown && op2.unknown)
          {
             return op1.value ? logical.UNKNOWN : logical.of(false);
          }

          return logical.of(op1.value && op2.value);
       }

       /**
        * Implements the <code>AND</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>true</code> and
        * <code>false</code> is returned if the other operand is
        * <code>false</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical AND.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical and(boolean op1, LogicalOp op2)
       {
          // ensure that the right operand will not be evaluated unless the
          // left operand is true
          if (!op1)
          {
             // if the left operand is false, it doesn't matter if the right
             // operand is unknown, we always return false
             return logical.of(false);
          }

          return and(op1, op2.evaluate());
       }

       /**
        * Implements the <code>AND</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>true</code> and
        * <code>false</code> is returned if the other operand is
        * <code>false</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical AND.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical and(logical op1, LogicalOp op2)
       {
          // ensure that the right operand will not be evaluated unless the
          // left operand is true or UNKNOWN
          if (!op1.isUnknown() && !op1.value)
          {
             // if the left operand is false, it doesn't matter if the right
             // operand is unknown, we always return false
             return logical.of(false);
          }

          return and(op1, op2.evaluate());
       }

       /**
        * Implements the <code>OR</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _or(boolean op1, boolean op2)
       {
          return op1 || op2;
       }

       /**
        * Implements the <code>OR</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _or(logical op1, boolean op2)
       {
          return op2 || (!op1.unknown && op1.value);
       }

       /**
        * Implements the <code>OR</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _or(boolean op1, logical op2)
       {
          return op1 || (!op2.unknown && op2.value);
       }

       /**
        * Implements the <code>OR</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _or(logical op1, logical op2)
       {
          return (!op1.unknown && op1.value) || (!op2.unknown && op2.value);
       }

       /**
        * Implements the <code>OR</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _or(boolean op1, LogicalOp op2)
       {
          return op1 || _or(op1, op2.evaluate());
       }

       /**
        * Implements the <code>OR</code> logical operator with the convenience
        * of converting the result to a primitive <code>boolean</code>. If the
        * result is the <code>unknown value</code>, this will be converted to a
        * <code>false</code>.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static boolean _or(logical op1, LogicalOp op2)
       {
          return (!op1.unknown && op1.value) || _or(op1, op2.evaluate());
       }

       /**
        * Implements the <code>OR</code> logical operator using the Java logical
        * OR.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical or(boolean op1, boolean op2)
       {
          return logical.of(op1 || op2);
       }

       /**
        * Implements the <code>OR</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>false</code> and
        * <code>true</code> is returned if the other operand is
        * <code>true</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical OR.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical or(boolean op1, logical op2)
       {
          return or(logical.of(op1), op2);
       }

       /**
        * Implements the <code>OR</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>false</code> and
        * <code>true</code> is returned if the other operand is
        * <code>true</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical OR.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical or(logical op1, boolean op2)
       {
          return or(op1, logical.of(op2));
       }

       /**
        * Implements the <code>OR</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>false</code> and
        * <code>true</code> is returned if the other operand is
        * <code>true</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical OR.
        * <p>
        * <b>Warning: this form requires that both operand expressions are
        * evaluated in the context of the caller.  It does not maintain the
        * standard semantic of a logical operator where the right operand is not
        * evaluated unless the left operand requires it.</b>
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical or(logical op1, logical op2)
       {
          if (op1.unknown && op2.unknown)
          {
             return logical.UNKNOWN;
          }

          if (op1.unknown && !op2.unknown)
          {
             return op2.value ? logical.of(true) : logical.UNKNOWN;
          }

          if (!op1.unknown && op2.unknown)
          {
             return op1.value ? logical.of(true) : logical.UNKNOWN;
          }

          return logical.of(op1.value || op2.value);
       }

       /**
        * Implements the <code>OR</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>false</code> and
        * <code>true</code> is returned if the other operand is
        * <code>true</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical OR.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical or(boolean op1, LogicalOp op2)
       {
          // ensure that the right operand will not be evaluated unless the
          // left operand is false or unknown
          if (op1)
          {
             return logical.of(true);
          }

          // unknown value processing is too complex to inline here, use the
          // common method even if it is a bit slower
          return or(logical.of(op1), op2.evaluate());
       }

       /**
        * Implements the <code>OR</code> logical operator with proper processing
        * of the <code>unknown value</code>.
        * <p>
        * If one operand is <code>unknown</code>, then <code>unknown</code>
        * is returned if the other operand is <code>false</code> and
        * <code>true</code> is returned if the other operand is
        * <code>true</code>.  If both operands are <code>unknown</code>, then
        * <code>unknown</code> is returned.
        * <p>
        * If no operand is <code>unknown</code>, the boolean values of each
        * logical are tested using the Java logical OR.
        * <p>
        * This form of the method allows the original semantic of the operator
        * to be maintained.  In particular, the expression defining the right
        * operand will not be evaluated unless the left operand does not fail
        * the logical test.
        *
        * @param    op1
        *           The left operand.
        * @param    op2
        *           The right operand.
        *
        * @return   The result of the operator.
        */
       public static logical or(logical op1, LogicalOp op2)
       {
          // ensure that the right operand will not be evaluated unless the
          // left operand is false or unknown
          if (!op1.isUnknown() && op1.value)
          {
             return logical.of(true);
          }

          return or(op1, op2.evaluate());
       }

       /**
        * Split a valid logical format string in a safe way that handles all
        * possible edge cases. Examples:
        * <p>
        * <ul>
        *    <li> an empty or <code>null</code> format string is invalid
        *    <li> a format that starts with '/' has an empty string for the
        *         <code>true</code> value
        *    <li> a format that ends with '/' or has no '/' has an empty string
        *         for the <code>false</code>
        *    <li> otherwise the format string is split into 2 pieces at the '/'
        *         character and the left side is used as the <code>true</code>
        *         representation and the right side is the <code>false</code>
        * </ul>
        *
        * @param    fmt
        *           Format to split.
        *
        * @return   The split format string as a string array with 2 elements,
        *           where the first element is the <code>true</code> value
        *           and the second element is the <code>false</code> value.
        *
        *           Return {@code null} if the provided format is invalid, and error was not thrown.
        *
        * @throws   ErrorConditionException
        *           if the provided format is invalid (null, empty or a single slash character).
        *           The error code is 74.
        */
       public static String[] splitFormat(String fmt)
       throws ErrorConditionException
       {
          // interestingly, only the empty string or the "/" are problems
          if (fmt == null || fmt.length() == 0 || fmt.equals("/"))
          {
             ErrorManager.recordOrThrowError(74,
                      String.format("Value %s cannot be displayed using %s", "", fmt));
             return null;
          }

          // usually, format strings must have 2 non-empty parts separated by a '/' so let's look for that char
          final int split = fmt.indexOf('/');
          if (split < 0)
          {
             // edge case where there is no '/' at all, use the whole ftm as the true value
             return new String[] { fmt, "" };
          }

          // It is an error in OE if format has more than one slash character.
          final int secondSlashIndex = fmt.indexOf('/', split + 1);
          if (secondSlashIndex > 0)
          {
             ErrorManager.genInvalidCharError(secondSlashIndex, fmt);
             return null;
          }

          return new String[] { fmt.substring(0, split), fmt.substring(split + 1) };
       }

       /**
        * Determines the largest possible string length that can match either of
        * the specified values in a valid format string.  For example, if the
        * format string was specified as "Yep/Nope" then the largest size would
        * be returned as 4.  The format string will be split and the length of
        * the larger of the 2 values will be returned.
        *
        * @param    fmt
        *           A valid format string for the <code>logical</code> type.
        *
        * @return   The length of the longer of the 2 values in the format
        *           string.
        */
       public static int maximumStringSize(String fmt)
       {
          if (fmt == null)
          {
             fmt = "";
          }

          String[] result = splitFormat(fmt);

          if (result == null)
          {
             result = new String[] { "", "" };
          }

          return Math.max(result[0].length(), result[1].length());
       }

       /**
        * Calculate the length of a formatted value (the text form of the value)
        * using this format string.
        *
        * @param    fmt
        *           The format string.
        *
        * @return   The length in characters of the any resulting formatted
        *           value.
        */
       public int formatLength(String fmt)
       {
          if (fmt == null)
          {
             fmt = defaultFormatString();
          }

          return maximumStringSize(fmt);
       }

       /**
        * An equality test which handles the most common cases with the least
        * amount of overhead.  The superclass implementation is invoked otherwise.
        * <p>
        * This implementation is consistent with {@link #hashCode()}.
        *
        * @see com.goldencode.p2j.util.BaseDataType#equals(java.lang.Object)
        */
       public boolean equals(Object o)
       {
          if (this == o)
          {
             return true;
          }

          if (o instanceof logical)
          {
             logical that = (logical) o;

             boolean u1 = this.unknown;
             boolean u2 = that.unknown;

             if (u1 && u2)
             {
                return true;
             }

             if (u1 || u2)
             {
                return false;
             }

             return (this.value == that.value);
          }

          return super.equals(o);
       }

       /**
        * Hash code implementation which is consistent with {@link
        * BaseDataType#equals}.
        *
        * @return  Hash code value for this object instance.
        */
       public int hashCode()
       {
          int result = 17;
          if (isUnknown())
          {
             return result;
          }

          result = 37 * result + (value ? 0 : 1);

          return result;
       }

       /**
        * Creates a new instance of the same type that represents the
        * <code>unknown value</code>.
        *
        * @return   An instance that represents the <code>unknown value</code>.
        */
       public BaseDataType instantiateUnknown()
       {
          return new logical();
       }

       /**
        * Creates a new instance of the same type that represents the
        * default initialized value.
        *
        * @return   An instance that represents the default value.
        */
       public BaseDataType instantiateDefault()
       {
          return new logical(false);
       }

       /**
        * Does the same as standard <code>clone()</code> method but returns an
        * instance of <code>BaseDataType</code> and doesn't throw the
        * <code>CloneNotSupportedException</code>.
        *
        * @return   A clone of this instance.
        */
       public logical duplicate()
       {
          return new logical(this);
       }

       /**
        * Accesses the state of this instance's <code>boolean</code> value. If
        * this instance represents the <code>unknown value</code>, then this
        * method will return <code>false</code> even if the internal state is
        * <code>true</code>!
        *
        * @return   The state of this instance's <code>boolean</code> value or
        *           <code>false</code> if this instance represents the
        *           <code>unknown value</code>.
        */
       public boolean booleanValue()
       {
          if (unknown)
             return false;

          return value;
       }

       /**
        * Determines if this instance represents the <code>unknown value</code>.
        *
        * @return   <code>true</code> if this instance is set to the
        *           <code>unknown value</code>.
        */
       public boolean isUnknown()
       {
          return unknown;
       }

       /**
        * Sets the state of this instance's <code>unknown value</code> flag to
        * <code>true</code>.
        * <p>
        * <b>Warning: a separate call is needed to ensure that the data of this
        * instance is set to the correct value.</b>
        */
       public void setUnknown()
       {
          if (!unknown)
          {
             checkUndoable(true);
          }

          unknown = true;
       }

       /**
        * Accesses the state of this instance's <code>boolean</code> value
        * independently of the state of whether this instance represents the
        * <code>unknown value</code>.    If this instance represents the
        * <code>unknown value</code>, the returned <code>boolean</code> is
        * <b>not valid</b>!
        *
        * @return   The state of this instance's <code>boolean</code> value.
        */
       public boolean getValue()
       {
          return value;
       }

       /**
        * Sets the state of this instance's <code>boolean</code> value
        * independently of the state of whether this instance represents the
        * <code>unknown value</code>.    This also sets the
        * <code>unknown value</code> state for this instance to
        * <code>false</code>.
        *
        * @param    value
        *           The state to set this instance's <code>boolean</code> value.
        */
       public void setValue(boolean value)
       {
          if (unknown || value != this.value)
          {
             checkUndoable(true);
          }

          this.value = value;
          unknown    = false;
       }

       /**
        * Returns {@code true} if dynamic data type conversion should not be attempted, it can also throw an
        * {@code ErrorConditionException} in case of incompatible types for a POLY conversion.
        * (e.g. DYNAMIC-FUNCTION()).
        *
        * @throws   ErrorConditionException
        *           If dynamic conversion of input value is not supported.
        */
       @Override
       protected boolean isIncompatibleTypesOnConversion(BaseDataType value)
       {
          // invalid conversion is being thrown even if unknown
          if (value instanceof longchar /*|| value instanceof clob*/ || value instanceof blob)
          {
             incompatibleTypesOnConversion();
          }

          return super.isIncompatibleTypesOnConversion(value);
       }

       /**
        * Sets the state (data and unknown value) of this instance based on the
        * state of the passed instance.
        * <p>
        * If the value is not of type <code>logical</code>, the following automatic type
        * conversions will occur:
        * <p>
        * <ol>
        *    <li> if the value is a logical value, the current value is returned</li>
        *    <li> if the value is unknown (including unknown literal), sets the instance to
        *         unknown</li>
        *    <li> if the value is a non-unknown rowid or BinaryData (raw or memptr) value the string
        *         representation is converted to a logical value</li>
        *    <li> if the value is a non-unknown numeric value, returns a logical value set to true
        *         when the numeric value is not zero, false if the numeric value is 0</li>
        *    <li> if the value is a non-unknown character or longchar value, it attempts to convert
        *         the character value to a logical value (if the character is "yes", it is set to
        *         true, if is "no", it is set to false</li>
        *    <li> if the value is a non-unknown date or datetime it returns a logical false for a
        *         value of 31/12/-4714 and true for other values. Basically the number of days from
        *         1/1/4713 B.C. to that date are converted to logical value. If the number of days
        *         are 0 a false value is returned otherwise a true value is returned.</li>
        *    <li> if the value is a non-unknown handle or comhandle value, it returns a logical
        *         false if the resource id is 0 and true if the resource id is not 0.</li>
        *    <li> else, it attempts to convert the value's string representation to logical</li>
        * </ol>
        * <p>
        * This variant is meant to handle the cases of built-in functions and methods in the 4GL
        * which have polymorphic return types (e.g. DYNAMIC-FUNCTION()). This should NOT be used for
        * non-polymorphic assignments.
        *
        * @param    value
        *           The instance from which to copy state.
        */
       public void assign(BaseDataType value)
       {
          if (value == null)
          {
             setUnknown();
             return;
          }

          // the value may be a proxy; make sure to unwrap and work with the real value
          value = value.val();
          if (value.isUnknown())
          {
             setUnknown();
          }
          else if (value instanceof logical)
          {
             assign((logical) value);
          }
          else if (value instanceof jobject)
          {
             assign((jobject<?>) value);
          }
          else
          {
             // this path is only used when type morphing is needed
             if (value instanceof date && !(value instanceof datetime))
             {
                // date values only
                long day = ((date) value).longValue();
                assign(day != 0);
             }
             else if (value instanceof handle)
             {
                Long id = ((handle) value).getResourceId();

                if (id != null)
                {
                   assign(id != 0);
                }
                else
                {
                   setUnknown();
                }
             }
             else if (value instanceof NumberType)
             {
                // decimal, integer, int64, recid
                BigDecimal decimalValue = ((NumberType) value).toBigDecimal();

                if (decimalValue == null)
                {
                   setUnknown();
                }
                else
                {
                   assign(decimalValue.signum() != 0);
                }
             }
             else if (value instanceof Text)
             {
                // yes/no character or longchar values can be converted
                assign(new logical(value.toStringMessage()));
             }
             else if (value instanceof raw)
             {
                setUnknown();
             }
             else
             {
                incompatibleTypesOnConversion();
             }
          }
       }

       /**
        * Sets the state (data and unknown value) of this instance based on the
        * state of the passed instance.
        *
        * @param    value
        *           The instance from which to copy state.
        */
       public void assign(logical value)
       {
          // the value may be a proxy; make sure to unwrap and work with the real value
          if (BaseDataType.isProxy(value))
          {
             assign(value.val());
             return;
          }
          checkUndoable(value);

          this.value = value.value;
          unknown    = value.unknown;
       }

       /**
        * Sets the state (data) of this instance based on the given value.
        *
        * @param    value
        *           The data from which to copy state.
        */
       public void assign(boolean value)
       {
          if (unknown || this.value != value)
          {
             checkUndoable(true);
          }

          this.value = value;
          unknown    = false;
       }

       /**
        * Sets the state (data and unknown value) of this instance based on the
        * state of the passed instance.
        *
        * @param    value
        *           The instance from which to copy state.
        */
       public void assign(Undoable value)
       {
          assign((logical) value);
       }

       /**
        * Compares this instance with the specified instance and returns a -1
        * if this instance is less than the specified, 0 if the two instances
        * are equal and 1 if this instance is greater than the specified
        * instance.  This is the implementation of the <code>Comparable</code>
        * interface.
        * <p>
        * The algorithm will fail to give meaningful results in the case where
        * one tries to sort against other objects that do not represent compatible
        * values.
        *
        * @param    obj
        *           The instance to compare against.
        *
        * @return   -1, 0 or 1 depending on if this instance is less than,
        *           equal to or greater (respectively) than the specified
        *           instance <code>obj</code>.
        */
       public int compareTo(Object obj)
       {
          logical l = null;

          if (obj instanceof logical)
          {
             l = (logical) obj;
          }
          else if (obj instanceof BaseDataType)
          {
             BaseDataType bdt = (BaseDataType) obj;

             if (isUnknown() && bdt.isUnknown())
             {
                return 0;
             }
             else if (isUnknown())
             {
                return -1;
             }
             else if (bdt.isUnknown())
             {
                return 1;
             }
             else
             {
                l = new logical(bdt);

                 // An unknown value should be always converted to a unknown logical value.
                 // A non-unknown value should be always converted to a non-unknown logical value.
                 // If an unknown value is converted to a non-unknown value the conversion fails.
                 // If a non-unknown value is converted to an unknown value the conversion fails.
                if (l.isUnknown() != bdt.isUnknown())
                {
                   incompatibleTypesOnConversion();
                }
             }
          }
          else if (obj instanceof Boolean)
          {
             l = logical.of(((Boolean) obj).booleanValue());
          }
          else if (obj instanceof String)
          {
             l = convertString((String)obj);

             // if an error occurred, we detect it here and return
             if (l == null)
             {
                return -1;
             }
          }
          else
          {
             return -1;
          }

          int result = 0;

          if (!unknown && !l.unknown)
          {
             if (value == l.value)
             {
                result = 0;
             }
             else if (!value && l.value)
             {
                result = -1;
             }
             else
             {
                result = 1;
             }
          }
          else
          {
             if (unknown == l.unknown)
             {
                result = 0;
             }
             else if (unknown)
             {
                result = -1;
             }
             else
             {
                result = 1;
             }
          }

          return result;
       }

       /**
        * Returns the larger (<code>false</code> is smaller than
        * <code>true</code>) of the current or passed-in instance.
        *
        * @param    l
        *           The instance to compare against.
        *
        * @return   The largest instance.
        */
       public logical maximum(logical l)
       {
          return (logical) super.maximum(l);
       }

       /**
        * Returns the smaller (<code>false</code> is smaller than
        * <code>true</code>) of the current or passed-in instance.
        *
        * @param    l
        *           The instance to compare against.
        *
        * @return   The smallest instance.
        */
       public logical minimum(logical l)
       {
          return (logical) super.minimum(l);
       }

       /**
        * Return the current value as a Java wrapper.
        *
        * @return  Current value or {@code null} if unknown.
        */
       public Boolean toJavaType()
       {
          return isUnknown() ? null : Boolean.valueOf(value);
       }

       /**
        * Creates a string representation of the instance data using the default Progress 4GL format of
        * {@code 'yes/no'}. If the instance represents the {@code unknown value}, a {@code '?'} will be returned.
        *
        * @return  A short string representation of the object.
        */
       public String toString()
       {
          return toString(null);
       }

       /**
        * Creates a string representation of the instance data in a form that is
        * compatible with the <code>MESSAGE</code> language statement.  If the
        * instance represents the <code>unknown value</code>, a '?' will be
        * returned.
        *
        * @return   The 'message' formatted string.
        */
       public String toStringMessage()
       {
          return toString(null);
       }

       /**
        * Creates a string representation of the instance data using the 'export'
        * format. For the logical data type this is the same as the default
        * format string of 'yes/no'.  If the instance represents the
        * <code>unknown value</code>, a '?' will be returned.
        *
        * @return   The 'export' formatted string.
        */
       public String toStringExport()
       {
          return toString(null);
       }

       /**
        * Creates a string representation of the instance data using the user-
        * specified Progress 4GL format string.  If the passed-in format is
        * <code>null</code>, then a default format string of 'yes/no' will be
        * used.  Please note that due to the implementation, it is faster
        * to use a <code>null</code> format string than to explicitly encode
        * 'yes/no'.  If the instance represents the <code>unknown value</code>,
        * a '?' will be returned.
        * <p>
        * The format string must be in the form of 'xxx/yyy' where xxx is the
        * text for a <code>true</code> and yyy is the text for a
        * <code>false</code> value.  For example, one might want a 'true/false'
        * to be used instead of the default.  The user cannot override the '?'
        * returned for the <code>unknown value</code>.
        *
        * @param    fmt
        *           The Progress 4GL format string for a logical data type.
        *
        * @return   The formatted string.
        */
       public String toString(String fmt)
       throws ErrorConditionException
       {
          // quick-out when unknown (no user override for that case)
          if (unknown)
          {
             return "?";
          }

          // implement 'default' behavior (as if the format string was "yes/no")
          if (fmt == null)
          {
             return value ? "yes" : "no";
          }

          String[] result = splitFormat(fmt);
          if (result == null)
          {
             return "";
          }

          StringBuilder res = new StringBuilder(value ? result[0] : result[1]);
          int fmtLen = formatLength(fmt);

          while(res.length() < fmtLen)
          {
             res.append(' ');
          }

          // normal case
          return res.toString();
       }

       /**
        * Return the default display format string for this type.
        *
        * @return   The default format string.
        */
       public String defaultFormatString()
       {
          return DEFAULT_FORMAT;
       }

       /**
        * Obtain the length (in bytes) of this BDT will use when serialized.
        *
        * @return  the length of this BDT will use when serialized.
        */
       @Override
       public int getSize()
       {
          return (isUnknown() || !value) ? 1 : 2;
       }

       /**
        * Replacement for the default object reading method. The latest
        * state is read from the input source.
        *
        * @param    in
        *           The input source from which fields will be restored.
        *
        * @throws   IOException
        *           In case of I/O errors.
        * @throws   ClassNotFoundException
        *           If payload can't be instantiated.
        */
       public void readExternal(ObjectInput in)
       throws IOException,
              ClassNotFoundException
       {
          value   = in.readBoolean();
          unknown = in.readBoolean();
       }

       /**
        * Replacement for the default object writing method. The latest
        * state is written to the output destination.
        *
        * @param    out
        *           The output destination to which fields will be saved.
        *
        * @throws   IOException
        *           In case of I/O errors.
        */
       public void writeExternal(ObjectOutput out)
       throws IOException
       {
          out.writeBoolean(value);
          out.writeBoolean(unknown);
       }

       /**
        * Get the default initialization for an extent variable of this type.
        *
        * @return   See above.
        */
       @Override
       protected BaseDataType instantiateDefaultExtent()
       {
          return logical.of(false);
       }

       /**
        * Helper to convert a text value into a logical value with ERROR
        * processing SUPPRESSED.  The only known instance where we use this is
        * in a validation expression, so the suppression of error processing
        * should be OK when it normally might be dangerous.
        *
        * @param    val
        *           The value to attempt to convert. If it does not match the
        *           string "yes" or "no", then an error would normally occur.
        *           This error will be suppressed, but the resulting failure
        *           will be detected.
        *
        * @return   The converted instance or <code>null</code> on any failure.
        */
       private logical convertString(String val)
       {
          logical[] l = new logical[1];

          try
          {
             ErrorManager.ignore(() -> l[0] = new logical(val));
          }

          catch (ErrorConditionException ece)
          {
             // should not happen but we put this here for safety
             return null;
          }

          // if an error silently occurred inside the logical constructor, we
          // detect it here and return
          if (l[0] != null && l[0].isUnknown())
          {
             l[0] = null;
          }

          return l[0];
       }

       /**
        * An immutable logical type, to be used for TRUE/FALSE/UNKNOWN singletons required within FWD runtime.
        * <p>
        * Instances of this type are serializable.
        */
       public static class logicalConstant
       extends logical
       implements BaseDataTypeConstant
       {
          /**
           * Default constructor, creates an instance that represents the unknown value.
           */
          public logicalConstant()
          {
             // unknown
          }

          /**
           * Constructs an instance that has the <code>boolean</code> value passed in and which <b>does not</b>
           * represent the <code>unknown value</code>.
           *
           * @param    value
           *           The logical value of the resulting instance.
           */
          public logicalConstant(boolean value)
          {
             super(value);
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void setUnknown()
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void setValue(boolean value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void assign(BaseDataType value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void assign(boolean value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void assign(jobject<?> value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void assign(logical value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void assign(Object value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          public void assign(Undoable value)
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }

          /**
           * Operation not possible.
           *
           * @throws   UnsupportedOperationException
           *           This is an immutable logical instance.
           */
          @Override
          Supplier<AbstractParameter> getAssigner()
          {
             throw new UnsupportedOperationException("This is an immutable logical instance.");
          }
       }
    }