OOPListSchemaVerifier.m

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/*
 
OOPListSchemaVerifier.m
 
 
Copyright (C) 2007-2013 Jens Ayton
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED ìAS ISî, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 
*/
 
#import "OOPListSchemaVerifier.h"
 
#if OO_OXP_VERIFIER_ENABLED
 
#import "OOLoggingExtended.h"
#import "OOCollectionExtractors.h"
#import "OOMaths.h"
#include <limits.h>
 
 
#define PLIST_VERIFIER_DEBUG_DUMP_ENABLED       1
 
 
enum
{
    // Largest allowable number of characters for string included in error message.
    kMaximumLengthForStringInErrorMessage       = 100
};
 
 
// Internal error codes.
enum
{
    kStartOfPrivateErrorCodes = kPListErrorLastErrorCode,
    
    kPListErrorFailedAndErrorHasBeenReported
};
 
 
#if PLIST_VERIFIER_DEBUG_DUMP_ENABLED
static BOOL             sDebugDump = NO;
 
#define DebugDumpIndent()       do { if (sDebugDump) OOLogIndent(); } while (0)
#define DebugDumpOutdent()      do { if (sDebugDump) OOLogOutdent(); } while (0)
#define DebugDumpPushIndent()   do { if (sDebugDump) OOLogPushIndent(); } while (0)
#define DebugDumpPopIndent()    do { if (sDebugDump) OOLogPopIndent(); } while (0)
#define DebugDump(...)          do { if (sDebugDump) OOLog(@"verifyOXP.verbose.plistDebugDump", __VA_ARGS__); } while (0)
#else
#define DebugDumpIndent()       do { } while (0)
#define DebugDumpOutdent()      do { } while (0)
#define DebugDumpPushIndent()   do { } while (0)
#define DebugDumpPopIndent()    do { } while (0)
#define DebugDump(...)          do { } while (0)
#endif
 
 
NSString * const kOOPListSchemaVerifierErrorDomain = @"org.aegidian.oolite.OOPListSchemaVerifier.ErrorDomain";
 
NSString * const kPListKeyPathErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier plist key path";
NSString * const kSchemaKeyPathErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier schema key path";
 
NSString * const kExpectedClassErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier expected class";
NSString * const kExpectedClassNameErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier expected class name";
NSString * const kUnknownKeyErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier unknown key";
NSString * const kMissingRequiredKeysErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier missing required keys";
NSString * const kMissingSubStringErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier missing substring";
NSString * const kUnnownFilterErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier unknown filter";
NSString * const kErrorsByOptionErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier errors by option";
 
NSString * const kUnknownTypeErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier unknown type";
NSString * const kUndefinedMacroErrorKey = @"org.aegidian.oolite.OOPListSchemaVerifier undefined macro";
 
 
typedef enum
{
    kTypeUnknown,
    kTypeString,
    kTypeArray,
    kTypeDictionary,
    kTypeInteger,
    kTypePositiveInteger,
    kTypeFloat,
    kTypePositiveFloat,
    kTypeOneOf,
    kTypeEnumeration,
    kTypeBoolean,
    kTypeFuzzyBoolean,
    kTypeVector,
    kTypeQuaternion,
    kTypeDelegatedType
} SchemaType;
 
 
typedef struct BackLinkChain BackLinkChain;
struct BackLinkChain
{
    BackLinkChain           *link;
    id                      element;
};
 
OOINLINE BackLinkChain BackLink(BackLinkChain *link, id element)
{
    BackLinkChain result = { link, element };
    return result;
}
 
OOINLINE BackLinkChain BackLinkIndex(BackLinkChain *link, NSUInteger index)
{
    BackLinkChain result = { link, [NSNumber numberWithInteger:index] };
    return result;
}
 
OOINLINE BackLinkChain BackLinkRoot(void)
{
    BackLinkChain result = { NULL, NULL };
    return result;
}
 
 
static SchemaType StringToSchemaType(NSString *string, NSError **outError);
static NSString *ApplyStringFilter(NSString *string, id filterSpec, BackLinkChain keyPath, NSError **outError);
static BOOL ApplyStringTest(NSString *string, id test, SEL testSelector, NSString *testDescription, BackLinkChain keyPath, NSError **outError);
static NSArray *KeyPathToArray(BackLinkChain keyPath);
static NSString *KeyPathToString(BackLinkChain keyPath);
static NSString *StringForErrorReport(NSString *string);
static NSString *ArrayForErrorReport(NSArray *array);
static NSString *SetForErrorReport(NSSet *set);
static NSString *StringOrArrayForErrorReport(id value, NSString *arrayPrefix);
 
static NSError *Error(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSString *format, ...);
static NSError *ErrorWithProperty(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSString *propKey, id propValue, NSString *format, ...);
static NSError *ErrorWithDictionary(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSDictionary *dict, NSString *format, ...);
static NSError *ErrorWithDictionaryAndArguments(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSDictionary *dict, NSString *format, va_list arguments);
 
static NSError *ErrorTypeMismatch(Class expectedClass, NSString *expectedClassName, id actualObject, BackLinkChain keyPath);
static NSError *ErrorFailureAlreadyReported(void);
static BOOL IsFailureAlreadyReportedError(NSError *error);
 
 
@interface OOPListSchemaVerifier (OOPrivate)
 
// Call delegate methods.
- (BOOL)delegateVerifierWithPropertyList:(id)rootPList
                                   named:(NSString *)name
                            testProperty:(id)subPList
                                  atPath:(BackLinkChain)keyPath
                             againstType:(NSString *)typeKey
                                   error:(NSError **)outError;
 
- (BOOL)delegateVerifierWithPropertyList:(id)rootPList
                                   named:(NSString *)name
                       failedForProperty:(id)subPList
                               withError:(NSError *)error
                            expectedType:(NSDictionary *)localSchema;
 
- (BOOL)verifyPList:(id)rootPList
              named:(NSString *)name
        subProperty:(id)subProperty
  againstSchemaType:(id)subSchema
             atPath:(BackLinkChain)keyPath
          tentative:(BOOL)tentative
              error:(NSError **)outError
               stop:(BOOL *)outStop;
 
- (NSDictionary *)resolveSchemaType:(id)specifier
                             atPath:(BackLinkChain)keyPath
                              error:(NSError **)outError;
 
@end
 
 
@interface NSString (OOPListSchemaVerifierHelpers)
 
- (BOOL)ooPListVerifierHasSubString:(NSString *)string;
 
@end
 
 
#define VERIFY_PROTO(T) static NSError *Verify_##T(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
VERIFY_PROTO(String);
VERIFY_PROTO(Array);
VERIFY_PROTO(Dictionary);
VERIFY_PROTO(Integer);
VERIFY_PROTO(PositiveInteger);
VERIFY_PROTO(Float);
VERIFY_PROTO(PositiveFloat);
VERIFY_PROTO(OneOf);
VERIFY_PROTO(Enumeration);
VERIFY_PROTO(Boolean);
VERIFY_PROTO(FuzzyBoolean);
VERIFY_PROTO(Vector);
VERIFY_PROTO(Quaternion);
VERIFY_PROTO(DelegatedType);
 
 
@implementation OOPListSchemaVerifier
 
+ (id)verifierWithSchema:(NSDictionary *)schema
{
    return [[[self alloc] initWithSchema:schema] autorelease];
}
 
 
- (id)initWithSchema:(NSDictionary *)schema
{
    self = [super init];
    if (self != nil)
    {
        _schema = [schema retain];
        _definitions = [[_schema oo_dictionaryForKey:@"$definitions"] retain];
        sDebugDump = [[NSUserDefaults standardUserDefaults] boolForKey:@"plist-schema-verifier-dump-structure"];
        if (sDebugDump)  OOLogSetDisplayMessagesInClass(@"verifyOXP.verbose.plistDebugDump", YES);
        
        if (_schema == nil)
        {
            [self release];
            self = nil;
        }
    }
    
    return self;
}
 
 
- (void)dealloc
{
    [_schema release];
    [_definitions release];
    
    [super dealloc];
}
 
 
- (void)setDelegate:(id)delegate
{
    if (_delegate != delegate)
    {
        _delegate = delegate;
        _badDelegateWarning = NO;
    }
}
 
 
- (id)delegate
{
    return _delegate;
}
 
 
- (BOOL)verifyPropertyList:(id)plist named:(NSString *)name
{
    BOOL                        OK;
    BOOL                        stop = NO;
    
    OK = [self verifyPList:plist
                     named:name
               subProperty:plist
         againstSchemaType:_schema
                    atPath:BackLinkRoot()
                 tentative:NO
                     error:NULL
                      stop:&stop];
    
    return OK;
}
 
 
+ (NSString *)descriptionForKeyPath:(NSArray *)keyPath
{
    NSMutableString             *result = nil;
    NSEnumerator                *componentEnum = nil;
    id                          component = nil;
    BOOL                        first = YES;
    
    result = [NSMutableString string];
    
    for (componentEnum = [keyPath objectEnumerator]; (component = [componentEnum nextObject]); )
    {
        if ([component isKindOfClass:[NSNumber class]])
        {
            [result appendFormat:@"[%@]", component];
        }
        else if ([component isKindOfClass:[NSString class]])
        {
            if (!first)  [result appendString:@"."];
            [result appendString:component];
        }
        else  return nil;
        first = NO;
    }
    
    if (first)
    {
        // Empty path
        return @"root";
    }
    
    return result;
}
 
@end
 
 
@implementation OOPListSchemaVerifier (OOPrivate)
 
- (BOOL)delegateVerifierWithPropertyList:(id)rootPList
                                   named:(NSString *)name
                            testProperty:(id)subPList
                                  atPath:(BackLinkChain)keyPath
                             againstType:(NSString *)typeKey
                                   error:(NSError **)outError
{
    BOOL                    result;
    NSError                 *error = nil;
    
    if ([_delegate respondsToSelector:@selector(verifier:withPropertyList:named:testProperty:atPath:againstType:error:)])
    {
        @try
        {
            result = [_delegate verifier:self
                        withPropertyList:rootPList
                                   named:name
                            testProperty:subPList
                                  atPath:KeyPathToArray(keyPath)
                             againstType:typeKey
                                   error:&error];
        }
        @catch (NSException *exception)
        {
            OOLog(@"plistVerifier.delegateException", @"Property list schema verifier: delegate threw exception (%@) in -verifier:withPropertyList:named:testProperty:atPath:againstType: for type \"%@\" at %@ in %@ -- treating as failure.", [exception name], typeKey,KeyPathToString(keyPath), name);
            result = NO;
            error = nil;
        }
        
        if (outError != NULL)
        {
            if (!result || error != nil)
            {
                // Note: Generates an error if delegate returned NO (meaning stop) or if delegate produced an error but did not request a stop.
                *outError = ErrorWithProperty(kPListDelegatedTypeError, &keyPath, NSUnderlyingErrorKey, error, @"Value at %@ does not match delegated type \"%@\".", KeyPathToString(keyPath), typeKey);
            }
            else *outError = nil;
        }
    }
    else
    {
        if (!_badDelegateWarning)
        {
            OOLog(@"plistVerifier.badDelegate", @"%@", @"Property list schema verifier: delegate does not handle delegated types.");
            _badDelegateWarning = YES;
        }
        result = YES;
    }
    
    return result;
}
 
 
- (BOOL)delegateVerifierWithPropertyList:(id)rootPList
                                   named:(NSString *)name
                       failedForProperty:(id)subPList
                               withError:(NSError *)error
                            expectedType:(NSDictionary *)localSchema
{
    BOOL                    result;
    
    if ([_delegate respondsToSelector:@selector(verifier:withPropertyList:named:failedForProperty:withError:expectedType:)])
    {
        @try
        {
            result = [_delegate verifier:self
                        withPropertyList:rootPList
                                   named:name
                       failedForProperty:subPList
                               withError:error
                            expectedType:localSchema];
        }
        @catch (NSException *exception)
        {
            OOLog(@"plistVerifier.delegateException", @"Property list schema verifier: delegate threw exception (%@) in -verifier:withPropertyList:named:failedForProperty:atPath:expectedType: at %@ in %@ -- stopping.", [exception name], [error plistKeyPathDescription], name);
            result = NO;
        }
    }
    else
    {
        OOLog(@"plistVerifier.failed", @"Verification of property list \"%@\" failed at %@: %@", name, [error plistKeyPathDescription], [error localizedFailureReason]);
        result = NO;
    }
    return result;
}
 
 
- (BOOL)verifyPList:(id)rootPList
              named:(NSString *)name
        subProperty:(id)subProperty
  againstSchemaType:(id)subSchema
             atPath:(BackLinkChain)keyPath
          tentative:(BOOL)tentative
              error:(NSError **)outError
               stop:(BOOL *)outStop
{
    SchemaType              type = kTypeUnknown;
    NSError                 *error = nil;
    NSDictionary            *resolvedSpecifier = nil;
    NSAutoreleasePool       *pool = nil;
    
    assert(outStop != NULL);
    
    pool = [[NSAutoreleasePool alloc] init];
    
    DebugDumpPushIndent();
    
    @try
    {
        DebugDumpIndent();
        
        resolvedSpecifier = [self resolveSchemaType:subSchema atPath:keyPath error:&error];
        if (resolvedSpecifier != nil)  type = StringToSchemaType([resolvedSpecifier objectForKey:@"type"], &error);
        
        #define VERIFY_CASE(T) case kType##T: error = Verify_##T(self, subProperty, resolvedSpecifier, rootPList, name, keyPath, tentative, outStop); break;
        
        switch (type)
        {
            VERIFY_CASE(String);
            VERIFY_CASE(Array);
            VERIFY_CASE(Dictionary);
            VERIFY_CASE(Integer);
            VERIFY_CASE(PositiveInteger);
            VERIFY_CASE(Float);
            VERIFY_CASE(PositiveFloat);
            VERIFY_CASE(OneOf);
            VERIFY_CASE(Enumeration);
            VERIFY_CASE(Boolean);
            VERIFY_CASE(FuzzyBoolean);
            VERIFY_CASE(Vector);
            VERIFY_CASE(Quaternion);
            VERIFY_CASE(DelegatedType);
            
            case kTypeUnknown:
                // resolveSchemaType:... or StringToSchemaType() should have provided an error.
                *outStop = YES;
        }
    }
    @catch (NSException *exception)
    {
        error = Error(kPListErrorInternal, (BackLinkChain *)&keyPath, @"Uncaught exception %@: %@ in plist verifier for \"%@\" at %@.", [exception name], [exception reason], name, KeyPathToString(keyPath));
    }
    
    DebugDumpPopIndent();
    
    if (error != nil)
    {
        if (!tentative && !IsFailureAlreadyReportedError(error))
        {
            *outStop = ![self delegateVerifierWithPropertyList:rootPList
                                                         named:name
                                             failedForProperty:subProperty
                                                     withError:error
                                                  expectedType:subSchema];
        }
        else if (tentative)  *outStop = YES;
    }
    
    if (outError != NULL && error != nil)
    {
        *outError = [error retain];
        [pool release];
        [error autorelease];
    }
    else
    {
        [pool release];
    }
    
    return error == nil;
}
 
 
- (NSDictionary *)resolveSchemaType:(id)specifier
                             atPath:(BackLinkChain)keyPath
                              error:(NSError **)outError
{
    id                      typeVal = nil;
    NSString                *complaint = nil;
    
    assert(outError != NULL);
    
    if (![specifier isKindOfClass:[NSString class]] && ![specifier isKindOfClass:[NSDictionary class]])  goto BAD_TYPE;
    
    for (;;)
    {
        if ([specifier isKindOfClass:[NSString class]])  specifier = [NSDictionary dictionaryWithObject:specifier forKey:@"type"];
        typeVal = [(NSDictionary *)specifier objectForKey:@"type"];
        
        if ([typeVal isKindOfClass:[NSString class]])
        {
            if ([typeVal hasPrefix:@"$"])
            {
                // Macro reference; look it up in $definitions
                specifier = [_definitions objectForKey:typeVal];
                if (specifier == nil)
                {
                    *outError = ErrorWithProperty(kPListErrorSchemaUndefiniedMacroReference, &keyPath, kUndefinedMacroErrorKey, typeVal, @"Bad schema: reference to undefined macro \"%@\".", StringForErrorReport(typeVal));
                    return nil;
                }
            }
            else
            {
                // Non-macro string
                return specifier;
            }
        }
        else if ([typeVal isKindOfClass:[NSDictionary class]])
        {
            specifier = typeVal;    
        }
        else
        {
            goto BAD_TYPE;
        }
    }
    
BAD_TYPE:
    // Error: bad type
    if (typeVal == nil)  complaint = @"no type specified";
    else  complaint = @"not string or dictionary";
                
    *outError = Error(kPListErrorSchemaBadTypeSpecifier, &keyPath, @"Bad schema: invalid type specifier for path %@ (%@).", KeyPathToString(keyPath), complaint);
    return nil;
}
 
@end
 
 
static SchemaType StringToSchemaType(NSString *string, NSError **outError)
{
    static NSDictionary         *typeMap = nil;
    SchemaType                  result;
    
    if (typeMap == nil)
    {
        typeMap =
            [[NSDictionary dictionaryWithObjectsAndKeys:
                [NSNumber numberWithUnsignedInt:kTypeString],           @"string",
                [NSNumber numberWithUnsignedInt:kTypeArray],            @"array",
                [NSNumber numberWithUnsignedInt:kTypeDictionary],       @"dictionary",
                [NSNumber numberWithUnsignedInt:kTypeInteger],          @"integer",
                [NSNumber numberWithUnsignedInt:kTypePositiveInteger],  @"positiveInteger",
                [NSNumber numberWithUnsignedInt:kTypeFloat],            @"float",
                [NSNumber numberWithUnsignedInt:kTypePositiveFloat],    @"positiveFloat",
                [NSNumber numberWithUnsignedInt:kTypeOneOf],            @"oneOf",
                [NSNumber numberWithUnsignedInt:kTypeEnumeration],      @"enumeration",
                [NSNumber numberWithUnsignedInt:kTypeBoolean],          @"boolean",
                [NSNumber numberWithUnsignedInt:kTypeFuzzyBoolean],     @"fuzzyBoolean",
                [NSNumber numberWithUnsignedInt:kTypeVector],           @"vector",
                [NSNumber numberWithUnsignedInt:kTypeQuaternion],       @"quaternion",
                [NSNumber numberWithUnsignedInt:kTypeDelegatedType],    @"delegatedType",
                nil
             ] retain];
    }
    
    result = [[typeMap objectForKey:string] unsignedIntValue];
    if (result == kTypeUnknown && outError != NULL)
    {
        if ([string hasPrefix:@"$"])
        {
            *outError = ErrorWithProperty(kPListErrorSchemaUnknownType, NULL, kUnknownTypeErrorKey, string, @"Bad schema: unresolved macro reference \"%@\".", string);
        }
        else
        {
            *outError = ErrorWithProperty(kPListErrorSchemaUnknownType, NULL, kUnknownTypeErrorKey, string, @"Bad schema: unknown type \"%@\".", string);
        }
    }
    
    return result;
}
 
 
static NSString *ApplyStringFilter(NSString *string, id filterSpec, BackLinkChain keyPath, NSError **outError)
{
    NSEnumerator            *filterEnum = nil;
    id                      filter = nil;
    NSRange                 range;
    
    assert(outError != NULL);
    
    if (filterSpec == nil)  return string;
    
    if ([filterSpec isKindOfClass:[NSString class]])
    {
        filterSpec = [NSArray arrayWithObject:filterSpec];
    }
    if ([filterSpec isKindOfClass:[NSArray class]])
    {
        for (filterEnum = [filterSpec objectEnumerator]; (filter = [filterEnum nextObject]); )
        {
            if ([filter isKindOfClass:[NSString class]])
            {
                if ([filter isEqual:@"lowerCase"])  string = [string lowercaseString];
                else if ([filter isEqual:@"upperCase"])  string = [string uppercaseString];
                else if ([filter isEqual:@"capitalized"])  string = [string capitalizedString];
                else if ([filter hasPrefix:@"truncFront:"])
                {
                    string = [string substringToIndex:[[filter substringFromIndex:11] intValue]];
                }
                else if ([filter hasPrefix:@"truncBack:"])
                {
                    string = [string substringToIndex:[[filter substringFromIndex:10] intValue]];
                }
                else if ([filter hasPrefix:@"subStringTo:"])
                {
                    range = [string rangeOfString:[filter substringFromIndex:12]];
                    if (range.location != NSNotFound)
                    {
                        string = [string substringToIndex:range.location];
                    }
                }
                else if ([filter hasPrefix:@"subStringFrom:"])
                {
                    range = [string rangeOfString:[filter substringFromIndex:14]];
                    if (range.location != NSNotFound)
                    {
                        string = [string substringFromIndex:range.location + range.length];
                    }
                }
                else if ([filter hasPrefix:@"subStringToInclusive:"])
                {
                    range = [string rangeOfString:[filter substringFromIndex:21]];
                    if (range.location != NSNotFound)
                    {
                        string = [string substringToIndex:range.location + range.length];
                    }
                }
                else if ([filter hasPrefix:@"subStringFromInclusive:"])
                {
                    range = [string rangeOfString:[filter substringFromIndex:23]];
                    if (range.location != NSNotFound)
                    {
                        string = [string substringFromIndex:range.location];
                    }
                }
                else
                {
                    *outError = ErrorWithProperty(kPListErrorSchemaUnknownFilter, &keyPath, kUnnownFilterErrorKey, filter, @"Bad schema: unknown string filter specifier \"%@\".", filter);
                }
            }
            else
            {
                *outError = Error(kPListErrorSchemaUnknownFilter, &keyPath, @"Bad schema: filter specifier is not a string.");
            }
        }
    }
    else
    {
        *outError = Error(kPListErrorSchemaUnknownFilter, &keyPath, @"Bad schema: \"filter\" must be a string or an array.");
    }
    
    return string;
}
 
 
static BOOL ApplyStringTest(NSString *string, id test, SEL testSelector, NSString *testDescription, BackLinkChain keyPath, NSError **outError)
{
    BOOL                    (*testIMP)(id, SEL, NSString *);
    NSEnumerator            *testEnum = nil;
    id                      subTest = nil;
    
    assert(outError != NULL);
    
    if (test == nil)  return YES;
    
    testIMP = (BOOL(*)(id, SEL, NSString *))[string methodForSelector:testSelector];
    if (testIMP == NULL)
    {
        *outError = Error(kPListErrorInternal, &keyPath, @"OOPListSchemaVerifier internal error: NSString does not respond to test selector %@.", NSStringFromSelector(testSelector));
        return NO;
    }
    
    if ([test isKindOfClass:[NSString class]])
    {
        test = [NSArray arrayWithObject:test];
    }
    
    if ([test isKindOfClass:[NSArray class]])
    {
        for (testEnum = [test objectEnumerator]; (subTest = [testEnum nextObject]); )
        {
            if ([subTest isKindOfClass:[NSString class]])
            {
                if (testIMP(string, testSelector, subTest))  return YES;
            }
            else
            {
                *outError = Error(kPListErrorSchemaBadComparator, &keyPath, @"Bad schema: required %@ is not a string.", testDescription);
                return NO;
            }
        }
    }
    else
    {
        *outError = Error(kPListErrorSchemaBadComparator, &keyPath, @"Bad schema: %@ requirement specification is not a string or array.", testDescription);
    }
    return NO;
}
 
 
static NSArray *KeyPathToArray(BackLinkChain keyPath)
{
    NSMutableArray          *result = nil;
    BackLinkChain           *curr = NULL;
    
    result = [NSMutableArray array];
    for (curr = &keyPath; curr != NULL; curr = curr->link)
    {
        if (curr->element != nil)  [result insertObject:curr->element atIndex:0];
    }
    
    return result;
}
 
 
static NSString *KeyPathToString(BackLinkChain keyPath)
{
    return [OOPListSchemaVerifier descriptionForKeyPath:KeyPathToArray(keyPath)];
}
 
 
static NSString *StringForErrorReport(NSString *string)
{
    id                      result = nil;
    
    if (kMaximumLengthForStringInErrorMessage < [string length])
    {
        string = [string substringToIndex:kMaximumLengthForStringInErrorMessage];
    }
    result = [NSMutableString stringWithString:string];
    [result replaceOccurrencesOfString:@"\t" withString:@"    " options:0 range:NSMakeRange(0, [string length])];
    [result replaceOccurrencesOfString:@"\r\n" withString:@" \\ " options:0 range:NSMakeRange(0, [string length])];
    [result replaceOccurrencesOfString:@"\n" withString:@" \\ " options:0 range:NSMakeRange(0, [string length])];
    [result replaceOccurrencesOfString:@"\r" withString:@" \\ " options:0 range:NSMakeRange(0, [string length])];
    
    if (kMaximumLengthForStringInErrorMessage < [result length])
    {
        result = [result substringToIndex:kMaximumLengthForStringInErrorMessage - 3];
        result = [result stringByAppendingString:@"..."];
    }
    
    return result;
}
 
 
static NSString *ArrayForErrorReport(NSArray *array)
{
    NSString                *result = nil;
    NSString                *string = nil;
    NSUInteger              i, count;
    NSAutoreleasePool       *pool = nil;
    
    count = [array count];
    if (count == 0)  return @"( )";
    
    pool = [[NSAutoreleasePool alloc] init];
    
    result = [NSString stringWithFormat:@"(%@", [array objectAtIndex:0]];
    
    for (i = 1; i != count; ++i)
    {
        string = [result stringByAppendingFormat:@", %@", [array objectAtIndex:i]];
        if (kMaximumLengthForStringInErrorMessage < [string length])
        {
            result = [result stringByAppendingString:@", ..."];
            break;
        }
        result = string;
    }
    
    result = [result stringByAppendingString:@")"];
    
    [result retain];
    [pool release];
    return [result autorelease];
}
 
 
static NSString *SetForErrorReport(NSSet *set)
{
    return ArrayForErrorReport([[set allObjects] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)]);
}
 
 
static NSString *StringOrArrayForErrorReport(id value, NSString *arrayPrefix)
{
    if ([value isKindOfClass:[NSString class]])
    {
        return [NSString stringWithFormat:@"\"%@\"", StringForErrorReport(value)];
    }
    
    if (arrayPrefix == nil)  arrayPrefix = @"";
    if ([value isKindOfClass:[NSArray class]])
    {
        return [arrayPrefix stringByAppendingString:ArrayForErrorReport(value)];
    }
    if ([value isKindOfClass:[NSSet class]])
    {
        return [arrayPrefix stringByAppendingString:SetForErrorReport(value)];
    }
    if (value == nil)  return @"(null)";
    return @"<?>";
}
 
 
// Specific type verifiers
 
#define REQUIRE_TYPE(CLASSNAME, NAMESTRING)  do { \
        if (![value isKindOfClass:[CLASSNAME class]]) \
        { \
            return ErrorTypeMismatch([CLASSNAME class], NAMESTRING, value, keyPath); \
        } \
    } while (0)
 
static NSError *Verify_String(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    NSString            *filteredString = nil;
    id                  testValue = nil;
    NSUInteger          length;
    NSUInteger          lengthConstraint;
    NSError             *error = nil;
    
    REQUIRE_TYPE(NSString, @"string");
    
    DebugDump(@"* string: \"%@\"", StringForErrorReport(value));
    
    // Apply filters
    filteredString = ApplyStringFilter(value, [params objectForKey:@"filter"], keyPath, &error);
    if (filteredString == nil)  return error;
    
    // Apply substring requirements
    testValue = [params objectForKey:@"requiredPrefix"];
    if (testValue != nil)
    {
        if (!ApplyStringTest(filteredString, testValue, @selector(hasPrefix:), @"prefix", keyPath, &error))
        {
            if (error == nil)  error = ErrorWithProperty(kPListErrorStringPrefixMissing, &keyPath, kMissingSubStringErrorKey, testValue, @"String \"%@\" does not have required %@ %@.", StringForErrorReport(value), @"prefix", StringOrArrayForErrorReport(testValue, @"in "));
            return error;
        }
    }
    
    testValue = [params objectForKey:@"requiredSuffix"];
    if (testValue != nil)
    {
        if (!ApplyStringTest(filteredString, testValue, @selector(hasSuffix:), @"suffix", keyPath, &error))
        {
            if (error == nil)  error = ErrorWithProperty(kPListErrorStringSuffixMissing, &keyPath, kMissingSubStringErrorKey, testValue, @"String \"%@\" does not have required %@ %@.", StringForErrorReport(value), @"suffix", StringOrArrayForErrorReport(testValue, @"in "));
            return error;
        }
    }
    
    testValue = [params objectForKey:@"requiredSubString"];
    if (testValue != nil)
    {
        if (!ApplyStringTest(filteredString, testValue, @selector(ooPListVerifierHasSubString:), @"substring", keyPath, &error))
        {
            if (error == nil)  error = ErrorWithProperty(kPListErrorStringSubstringMissing, &keyPath, kMissingSubStringErrorKey, testValue, @"String \"%@\" does not have required %@ %@.", StringForErrorReport(value), @"substring", StringOrArrayForErrorReport(testValue, @"in "));
            return error;
        }
    }
    
    // Apply length bounds.
    length = [filteredString length];
    lengthConstraint = [params oo_unsignedIntegerForKey:@"minLength"];
    if (length < lengthConstraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"String \"%@\" is too short (%u bytes, minimum is %u).", StringForErrorReport(filteredString), length, lengthConstraint);
    }
    
    lengthConstraint = [params oo_unsignedIntegerForKey:@"maxLength" defaultValue:NSUIntegerMax];
    if (lengthConstraint < length)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"String \"%@\" is too long (%u bytes, maximum is %u).", StringForErrorReport(filteredString), length, lengthConstraint);
    }
    
    // All tests passed.
    return nil;
}
 
 
static NSError *Verify_Array(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    id                      valueType = nil;
    BOOL                    OK = YES, stop = NO;
    NSUInteger              i, count;
    id                      subProperty = nil;
    NSUInteger              constraint;
    
    REQUIRE_TYPE(NSArray, @"array");
    
    DebugDump(@"%@", @"* array");
    
    // Apply count bounds.
    count = [value count];
    constraint = [params oo_unsignedIntegerForKey:@"minCount" defaultValue:0];
    if (count < constraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"Array has too few members (%u, minimum is %u).", count, constraint);
    }
    
    constraint = [params oo_unsignedIntegerForKey:@"maxCount" defaultValue:NSUIntegerMax];
    if (constraint < count)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"Array has too many members (%u, maximum is %u).", count, constraint);
    }
    
    // Test member objects.
    valueType = [params objectForKey:@"valueType"];
    if (valueType != nil)
    {
        for (i = 0; i != count; ++i)
        {
            subProperty = [value objectAtIndex:i];
            
            if (![verifier verifyPList:rootPList
                                 named:name
                           subProperty:subProperty
                     againstSchemaType:valueType
                                atPath:BackLinkIndex(&keyPath, i)
                             tentative:tentative
                                 error:NULL
                                  stop:&stop])
            {
                OK = NO;
            }
            
            if ((stop && !tentative) || (tentative && !OK))  break;
        }
    }
    
    *outStop = stop && !tentative;
    
    if (!OK)  return ErrorFailureAlreadyReported();
    else  return nil;
}
 
 
static NSError *Verify_Dictionary(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    NSDictionary            *schema = nil;
    id                      valueType = nil,
                            typeSpec = nil;
    NSEnumerator            *keyEnum = nil;
    NSString                *key = nil;
    id                      subProperty = nil;
    BOOL                    OK = YES, stop = NO, prematureExit = NO;
    BOOL                    allowOthers;
    NSMutableSet            *requiredKeys = nil;
    NSArray                 *requiredKeyList = nil;
    NSUInteger              count, constraint;
    
    REQUIRE_TYPE(NSDictionary, @"dictionary");
    
    DebugDump(@"%@", @"* dictionary");
    
    // Apply count bounds.
    count = [value count];
    constraint = [params oo_unsignedIntegerForKey:@"minCount" defaultValue:0];
    if (count < constraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"Dictionary has too few pairs (%u, minimum is %u).", count, constraint);
    }
    constraint = [params oo_unsignedIntegerForKey:@"maxCount" defaultValue:NSUIntegerMax];
    if (constraint < count)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"Dictionary has too manu pairs (%u, maximum is %u).", count, constraint);
    }
    
    // Get schema.
    schema = [params oo_dictionaryForKey:@"schema"];
    valueType = [params objectForKey:@"valueType"];
    allowOthers = [params oo_boolForKey:@"allowOthers" defaultValue:YES];
    requiredKeyList = [params oo_arrayForKey:@"requiredKeys"];
    
    // If these conditions are met, all members must pass:
    if (schema == nil && valueType == nil && requiredKeyList == nil && allowOthers)  return nil;
    
    if (requiredKeyList != nil)
    {
        requiredKeys = [NSMutableSet setWithArray:requiredKeyList];
    }
    
    DebugDumpIndent();
    
    // Test member objects.
    for (keyEnum = [value keyEnumerator]; (key = [keyEnum nextObject]) && !stop; )
    {
        subProperty = [(NSDictionary *)value objectForKey:key];
        typeSpec = [schema objectForKey:key];
        if (typeSpec == nil)  typeSpec = valueType;
        
        DebugDump(@"- \"%@\"", key);
        DebugDumpIndent();
        
        if (typeSpec != nil)
        {
            if (![verifier verifyPList:rootPList
                                 named:name
                           subProperty:subProperty
                     againstSchemaType:typeSpec
                                atPath:BackLink(&keyPath, key)
                             tentative:tentative
                                 error:NULL
                                  stop:&stop])
            {
                OK = NO;
            }
        }
        else if (!allowOthers && ![requiredKeys containsObject:key] && [schema objectForKey:key] == nil)
        {
            // Report error now rather than returning it, since there may be several unknown keys.
            if (!tentative)
            {
                NSError *error = ErrorWithProperty(kPListErrorDictionaryUnknownKey, &keyPath, kUnknownKeyErrorKey, key, @"Unpermitted key \"%@\" in dictionary.", StringForErrorReport(key));
                stop = ![verifier delegateVerifierWithPropertyList:rootPList
                                                             named:name
                                                 failedForProperty:value
                                                         withError:error
                                                      expectedType:params];
            }
            OK = NO;
        }
        
        DebugDumpOutdent();
        
        [requiredKeys removeObject:key];
        
        if ((stop && !tentative) || (tentative && !OK))
        {
            prematureExit = YES;
            break;
        }
    }
    
    DebugDumpOutdent();
    
    // Check that all required keys were present.
    if (!prematureExit && [requiredKeys count] != 0)
    {
        return ErrorWithProperty(kPListErrorDictionaryMissingRequiredKeys, &keyPath, kMissingRequiredKeysErrorKey, requiredKeys, @"Required keys %@ missing from dictionary.", SetForErrorReport(requiredKeys));
    }
    
    *outStop = stop && !tentative;
    
    if (!OK)  return ErrorFailureAlreadyReported();
    else  return nil;
}
 
 
static NSError *Verify_Integer(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    long long               numericValue;
    long long               constraint;
    
    numericValue = OOLongLongFromObject(value, 0);
    
    DebugDump(@"* integer: %lli", numericValue);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (numericValue != OOLongLongFromObject(value, 1))
    {
        return ErrorTypeMismatch([NSNumber class], @"integer", value, keyPath);
    }
    
    // Check constraints.
    constraint = [params oo_longLongForKey:@"minimum" defaultValue:LLONG_MIN];
    if (numericValue < constraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"Number is too small (%lli, minimum is %lli).", numericValue, constraint);
    }
    
    constraint = [params oo_longLongForKey:@"maximum" defaultValue:LLONG_MAX];
    if (constraint < numericValue)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"Number is too large (%lli, maximum is %lli).", numericValue, constraint);
    }
    
    return nil;
}
 
 
static NSError *Verify_PositiveInteger(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    unsigned long long      numericValue;
    unsigned long long      constraint;
    
    numericValue = OOUnsignedLongLongFromObject(value, 0);
    
    DebugDump(@"* positive integer: %llu", numericValue);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (numericValue != OOUnsignedLongLongFromObject(value, 1))
    {
        return ErrorTypeMismatch([NSNumber class], @"positive integer", value, keyPath);
    }
    
    // Check constraints.
    constraint = [params oo_unsignedLongLongForKey:@"minimum" defaultValue:0];
    if (numericValue < constraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"Number is too small (%llu, minimum is %llu).", numericValue, constraint);
    }
    
    constraint = [params oo_unsignedLongLongForKey:@"maximum" defaultValue:ULLONG_MAX];
    if (constraint < numericValue)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"Number is too large (%llu, maximum is %llu).", numericValue, constraint);
    }
    
    return nil;
}
 
 
static NSError *Verify_Float(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    double                  numericValue;
    double                  constraint;
    
    numericValue = OODoubleFromObject(value, 0);
    
    DebugDump(@"* float: %g", numericValue);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (numericValue != OODoubleFromObject(value, 1))
    {
        return ErrorTypeMismatch([NSNumber class], @"number", value, keyPath);
    }
    
    // Check constraints.
    constraint = [params oo_doubleForKey:@"minimum" defaultValue:-INFINITY];
    if (numericValue < constraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"Number is too small (%g, minimum is %g).", numericValue, constraint);
    }
    
    constraint = [params oo_doubleForKey:@"maximum" defaultValue:INFINITY];
    if (constraint < numericValue)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"Number is too large (%g, maximum is %g).", numericValue, constraint);
    }
    
    return nil;
}
 
 
static NSError *Verify_PositiveFloat(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    double                  numericValue;
    double                  constraint;
    
    numericValue = OODoubleFromObject(value, 0);
    
    DebugDump(@"* positive float: %g", numericValue);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (numericValue != OODoubleFromObject(value, 1))
    {
        return ErrorTypeMismatch([NSNumber class], @"positive number", value, keyPath);
    }
    
    if (numericValue < 0)
    {
        return Error(kPListErrorNumberIsNegative, &keyPath, @"Expected non-negative number, found %g.", numericValue);
    }
    
    // Check constraints.
    constraint = [params oo_doubleForKey:@"minimum" defaultValue:0];
    if (numericValue < constraint)
    {
        return  Error(kPListErrorMinimumConstraintNotMet, &keyPath, @"Number is too small (%g, minimum is %g).", numericValue, constraint);
    }
    
    constraint = [params oo_doubleForKey:@"maximum" defaultValue:INFINITY];
    if (constraint < numericValue)
    {
        return  Error(kPListErrorMaximumConstraintNotMet, &keyPath, @"Number is too large (%g, maximum is %g).", numericValue, constraint);
    }
    
    return nil;
}
 
 
static NSError *Verify_OneOf(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    NSArray                 *options = nil;
    BOOL                    OK = NO, stop = NO;
    NSEnumerator            *optionEnum = nil;
    id                      option = nil;
    NSError                 *error;
    NSMutableDictionary     *errors = nil;
    
    DebugDump(@"%@", @"* oneOf");
    
    options = [params oo_arrayForKey:@"options"];
    if (options == nil)
    {
        *outStop = YES;
        return Error(kPListErrorSchemaNoOneOfOptions, &keyPath, @"Bad schema: no options specified for oneOf type.");
    }
    
    errors = [[NSMutableDictionary alloc] initWithCapacity:[options count]];
    
    for (optionEnum = [options objectEnumerator]; (option = [optionEnum nextObject]) ;)
    {
        if ([verifier verifyPList:rootPList
                            named:name
                      subProperty:value
                againstSchemaType:option
                           atPath:keyPath
                        tentative:YES
                            error:&error
                             stop:&stop])
        {
            DebugDump(@"%@", @"> Match.");
            OK = YES;
            break;
        }
        [errors setObject:error forKey:option];
    }
    
    if (!OK)
    {
        DebugDump(@"%@", @"! No match.");
        return ErrorWithProperty(kPListErrorOneOfNoMatch, &keyPath, kErrorsByOptionErrorKey, [errors autorelease], @"No matching type rule could be found.");
    }
    
    // Ignore stop in tentatives.
    [errors release];
    return nil;
}
 
 
static NSError *Verify_Enumeration(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    NSArray                 *values = nil;
    NSString                *filteredString = nil;
    NSError                 *error = nil;
    
    DebugDump(@"%@", @"* enumeration");
    
    REQUIRE_TYPE(NSString, @"string");
    
    values = [params oo_arrayForKey:@"values"];
    DebugDump(@"  - \"%@\" in %@", StringForErrorReport(value), ArrayForErrorReport(values));
    
    if (values == nil)
    {
        *outStop = YES;
        return Error(kPListErrorSchemaNoEnumerationValues, &keyPath, @"Bad schema: no options specified for oneOf type.");
    }
    
    filteredString = ApplyStringFilter(value, [params objectForKey:@"filter"], keyPath, &error);
    if (filteredString == nil)  return error;
    
    if ([values containsObject:filteredString])  return nil;
    
    return Error(kPListErrorEnumerationBadValue, &keyPath, @"Value \"%@\" not recognized, should be one of %@.", StringForErrorReport(value), ArrayForErrorReport(values));
}
 
 
static NSError *Verify_Boolean(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    DebugDump(@"* boolean: %@", value);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (OOBooleanFromObject(value, 0) == OOBooleanFromObject(value, 1))  return nil;
    else  return ErrorTypeMismatch([NSNumber class], @"boolean", value, keyPath);
}
 
 
static NSError *Verify_FuzzyBoolean(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    DebugDump(@"* fuzzy boolean: %@", value);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (OODoubleFromObject(value, 0) == OODoubleFromObject(value, 1))  return nil;
    else if (OOBooleanFromObject(value, 0) == OOBooleanFromObject(value, 1))  return nil;
    else  return ErrorTypeMismatch([NSNumber class], @"fuzzy boolean", value, keyPath);
}
 
 
static NSError *Verify_Vector(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    DebugDump(@"* vector: %@", value);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (vector_equal(OOVectorFromObject(value, kZeroVector), OOVectorFromObject(value, kBasisXVector)))  return nil;
    else  return ErrorTypeMismatch(Nil, @"vector", value, keyPath);
}
 
 
static NSError *Verify_Quaternion(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    DebugDump(@"* quaternion: %@", value);
    
    // Check basic parseability. If there's inequality here, the default value is being returned.
    if (quaternion_equal(OOQuaternionFromObject(value, kZeroQuaternion), OOQuaternionFromObject(value, kIdentityQuaternion)))  return nil;
    else  return ErrorTypeMismatch(Nil, @"quaternion", value, keyPath);
}
 
 
static NSError *Verify_DelegatedType(OOPListSchemaVerifier *verifier, id value, NSDictionary *params, id rootPList, NSString *name, BackLinkChain keyPath, BOOL tentative, BOOL *outStop)
{
    id                      baseType = nil;
    NSString                *key = nil;
    BOOL                    stop = NO;
    NSError                 *error = nil;
    
    DebugDump(@"* delegated type: %@", [params objectForKey:@"key"]);
    
    baseType = [params objectForKey:@"baseType"];
    if (baseType != nil)
    {
        if (![verifier verifyPList:rootPList
                             named:name
                       subProperty:value
                 againstSchemaType:baseType
                            atPath:keyPath
                         tentative:tentative
                             error:NULL
                              stop:&stop])
        {
            *outStop = stop;
            return nil;
        }
    }
    
    key = [params objectForKey:@"key"];
    *outStop = ![verifier delegateVerifierWithPropertyList:rootPList
                                                     named:name
                                              testProperty:value
                                                    atPath:keyPath
                                               againstType:key
                                                     error:&error];
    return error;
}
 
 
@implementation NSString (OOPListSchemaVerifierHelpers)
 
- (BOOL)ooPListVerifierHasSubString:(NSString *)string
{
    return [self rangeOfString:string].location != NSNotFound;
}
 
@end
 
 
@implementation NSError (OOPListSchemaVerifierConveniences)
 
- (NSArray *)plistKeyPath
{
    return [[self userInfo] oo_arrayForKey:kPListKeyPathErrorKey];
}
 
 
- (NSString *)plistKeyPathDescription
{
    return [OOPListSchemaVerifier descriptionForKeyPath:[self plistKeyPath]];
}
 
 
- (NSSet *)missingRequiredKeys
{
    return [[self userInfo] oo_setForKey:kMissingRequiredKeysErrorKey];
}
 
 
- (Class)expectedClass
{
    return [[self userInfo] objectForKey:kExpectedClassErrorKey];
}
 
 
- (NSString *)expectedClassName
{
    NSString *result = [[self userInfo] objectForKey:kExpectedClassNameErrorKey];
    if (result == nil)  result = [[self expectedClass] description];
    return result;
}
 
@end
 
 
static NSError *Error(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSString *format, ...)
{
    NSError             *result = nil;
    va_list             args;
    
    va_start(args, format);
    result = ErrorWithDictionaryAndArguments(errorCode, keyPath, nil, format, args);
    va_end(args);
    
    return result;
}
 
 
static NSError *ErrorWithProperty(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSString *propKey, id propValue, NSString *format, ...)
{
    NSError             *result = nil;
    va_list             args;
    NSDictionary        *dict = nil;
    
    if (propKey != nil && propValue != nil)
    {
        dict = [NSDictionary dictionaryWithObject:propValue forKey:propKey];
    }
    va_start(args, format);
    result = ErrorWithDictionaryAndArguments(errorCode, keyPath, dict, format, args);
    va_end(args);
    
    return result;
}
 
 
static NSError *ErrorWithDictionary(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSDictionary *dict, NSString *format, ...)
{
    NSError             *result = nil;
    va_list             args;
    
    va_start(args, format);
    result = ErrorWithDictionaryAndArguments(errorCode, keyPath, dict, format, args);
    va_end(args);
    
    return result;
}
 
 
static NSError *ErrorWithDictionaryAndArguments(OOPListSchemaVerifierErrorCode errorCode, BackLinkChain *keyPath, NSDictionary *dict, NSString *format, va_list arguments)
{
    NSString            *message = nil;
    NSMutableDictionary *userInfo = nil;
    
    message = [[NSString alloc] initWithFormat:format arguments:arguments];
    
    userInfo = [NSMutableDictionary dictionaryWithDictionary:dict];
    [userInfo setObject:message forKey:NSLocalizedFailureReasonErrorKey];
    if (keyPath != NULL)
    {
        [userInfo setObject:KeyPathToArray(*keyPath) forKey:kPListKeyPathErrorKey];
    }
    
    [message release];
    
    return [NSError errorWithDomain:kOOPListSchemaVerifierErrorDomain code:errorCode userInfo:userInfo];
}
 
 
static NSError *ErrorTypeMismatch(Class expectedClass, NSString *expectedClassName, id actualObject, BackLinkChain keyPath)
{
    NSDictionary        *dict = nil;
    NSString            *className = nil;
    
    if (expectedClassName == nil)  expectedClassName = [expectedClass description];
    
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
                expectedClassName, kExpectedClassNameErrorKey,
                expectedClass, kExpectedClassErrorKey,
                nil];
    
    if (actualObject == nil)  className = @"nothing";
    else if ([actualObject isKindOfClass:[NSString class]])  className = @"string";
    else if ([actualObject isKindOfClass:[NSNumber class]])  className = @"number";
    else if ([actualObject isKindOfClass:[NSArray class]])  className = @"array";
    else if ([actualObject isKindOfClass:[NSDictionary class]])  className = @"dictionary";
    else if ([actualObject isKindOfClass:[NSData class]])  className = @"data";
    else if ([actualObject isKindOfClass:[NSDate class]])  className = @"date";
    else  className = [[actualObject class] description];
    
    return ErrorWithDictionary(kPListErrorTypeMismatch, &keyPath, dict, @"Expected %@, found %@.", expectedClassName, className);
}
 
 
static NSError *ErrorFailureAlreadyReported(void)
{
    return [NSError errorWithDomain:kOOPListSchemaVerifierErrorDomain code:kPListErrorFailedAndErrorHasBeenReported userInfo:nil];
}
 
 
static BOOL IsFailureAlreadyReportedError(NSError *error)
{
    return [[error domain] isEqualToString:kOOPListSchemaVerifierErrorDomain] && [error code] == kPListErrorFailedAndErrorHasBeenReported;
}
 
#endif  // OO_OXP_VERIFIER_ENABLED