Various improvements to server capability/version checking, including:

- Add a new ServerSupport class, for which an instance is created upon each new connection and is then subsequently accessible via SPDatabaseDocument.
- Replace the majority of manual version checking with calls to properties in the above new class.
- Improve the user manager's compatibility with MySQL 3 and 4 servers. Fixes issue #811

Other changes include:

- Disable the encoding popup button when adding a new table or database to servers running pre MySQL 4.1 as it only contains one option, 'Default'.
- Fix various potential memory leaks discovered during static analysis.
- General tidy up and comments.

1 files changed, 311 insertions, 0 deletions

diff --git a/Source/SPServerSupport.m b/Source/SPServerSupport.m
new file mode 100644
index 00000000..3f8227d9
--- /dev/null
+++ b/Source/SPServerSupport.m
@@ -0,0 +1,311 @@
+//
+//  $Id$
+//
+//  SPServerSupport.m
+//  sequel-pro
+//
+//  Created by Stuart Connolly (stuconnolly.com) on September 23, 2010
+//  Copyright (c) 2010 Stuart Connolly. All rights reserved.
+//
+//  This program is free software; you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation; either version 2 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 General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+//  More info at <http://code.google.com/p/sequel-pro/>
+
+#import "SPServerSupport.h"
+#import <objc/runtime.h>
+
+@interface SPServerSupport (PrivateAPI)
+
+- (void)_invalidate;
+- (NSComparisonResult)_compareServerMajorVersion:(NSInteger)majorVersionA 
+										   minor:(NSInteger)minorVersionA 
+										 release:(NSInteger)releaseVersionA
+						  withServerMajorVersion:(NSInteger)majorVersionB
+										   minor:(NSInteger)minorVersionB
+										 release:(NSInteger)releaseVersionB;
+
+@end
+
+@implementation SPServerSupport
+
+@synthesize isMySQL3;
+@synthesize isMySQL4;
+@synthesize isMySQL5;
+@synthesize isMySQL6;
+@synthesize supportsInformationSchema;
+@synthesize supportsShowCharacterSet;
+@synthesize supportsCharacterSetDatabaseVar;
+@synthesize supportsPost41CharacterSetHandling;
+@synthesize supportsCreateUser;
+@synthesize supportsDropUser;
+@synthesize supportsFullDropUser;
+@synthesize supportsUserMaxVars;
+@synthesize supportsShowPrivileges;
+@synthesize supportsInformationSchemaEngines;
+@synthesize supportsPre41StorageEngines;
+@synthesize supportsBlackholeStorageEngine;
+@synthesize supportsArchiveStorageEngine;
+@synthesize supportsCSVStorageEngine;
+@synthesize supportsTriggers;
+@synthesize supportsIndexKeyBlockSize;
+@synthesize serverMajorVersion;
+@synthesize serverMinorVersion;
+@synthesize serverReleaseVersion;
+
+#pragma mark -
+#pragma mark Initialization
+
+/**
+ * Creates and returns an instance of SPServerSupport with the supplied version numbers. The caller is
+ * responsible it's memory.
+ *
+ * @param majorVersion   The major version number of the server
+ * @param minorVersion   The minor version number of the server
+ * @param releaseVersiod The release version number of the server
+ *
+ * @return The initializes SPServerSupport instance
+ */
+- (id)initWithMajorVersion:(NSInteger)majorVersion minor:(NSInteger)minorVersion release:(NSInteger)releaseVersion
+{
+	if ((self == [super init])) {
+		
+		serverMajorVersion   = majorVersion;
+		serverMinorVersion   = minorVersion;
+		serverReleaseVersion = releaseVersion;
+		
+		// Determine what the server supports
+		[self evaluate];
+	}
+	
+	return self;
+}
+
+#pragma mark -
+#pragma mark Public API
+
+/**
+ * Performs the actual version based comparisons to determine what functionaity the server supports. This
+ * method is called automatically as part of the designated initializer (initWithMajorVersion:major:minor:release:)
+ * and shouldn't really need to be called again throughout a connection's lifetime.
+ *
+ * Note that for the sake of simplicity this method does not try to be smart in that it does not assume
+ * the presence of functionality based on a previous version check. This allows adding new ivars in the 
+ * future a matter of simply performing a new version comparison.
+ *
+ * To add a new metod for determining a server's support for specific functionality, simply add a new 
+ * (read only) ivar with the prefix 'supports' and peform the version checking within this method.
+ */
+- (void)evaluate
+{
+	// By default, assumme the server doesn't support anything
+	[self _invalidate];
+	
+	isMySQL3 = (serverMajorVersion == 3);
+	isMySQL4 = (serverMajorVersion == 4);
+	isMySQL5 = (serverMajorVersion == 5);
+	isMySQL6 = (serverMajorVersion == 6);
+	
+	// The information schema database wasn't added until MySQL 5
+	supportsInformationSchema = (serverMajorVersion >= 5);
+	
+	// The SHOW CHARACTER SET statement wasn't added until MySQL 4.1.0
+	supportsShowCharacterSet = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:0];
+	
+	// The variable 'character_set_database' wasn't added until MySQL 4.1.1
+	supportsCharacterSetDatabaseVar = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:1];
+	
+	// As of MySQL 4.1 encoding support was greatly improved
+	supportsPost41CharacterSetHandling = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:0];
+	
+	// The table information_schema.engines wasn't added until MySQL 5.1.5
+	supportsInformationSchemaEngines = [self isEqualToOrGreaterThanMajorVersion:5 minor:1 release:1];
+	
+	// The CREATE USER statement wasn't added until MySQL 5.0.2
+	supportsCreateUser = [self isEqualToOrGreaterThanMajorVersion:5 minor:0 release:2];
+	
+	// The DROP USER statement wasn't added until MySQL 4.1.1
+	supportsDropUser = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:1];
+	
+	// Similarly before MySQL 5.0.2 the DROP USER statement only removed users with no privileges
+	supportsFullDropUser = [self isEqualToOrGreaterThanMajorVersion:5 minor:0 release:2];
+	
+	// The maximum user variable columns (within mysql.user) weren't added until MySQL 4.0.2
+	supportsUserMaxVars = [self isEqualToOrGreaterThanMajorVersion:4 minor:0 release:2];
+	
+	// The SHOW PRIVILEGES statement wasn't added until MySQL 4.1.0
+	supportsShowPrivileges = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:0];
+	
+	// Before MySQL 4.1 the MEMORY engine was known as HEAP and the ISAM engine was available
+	supportsPre41StorageEngines = (![self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:0]);
+	
+	// The BLACKHOLE storage engine wasn't added until MySQL 4.1.11
+	supportsBlackholeStorageEngine = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:11];
+	
+	// The ARCHIVE storage engine wasn't added until MySQL 4.1.3
+	supportsArchiveStorageEngine = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:3];
+	
+	// The CSV storage engine wasn't added until MySQL 4.1.4
+	supportsCSVStorageEngine = [self isEqualToOrGreaterThanMajorVersion:4 minor:1 release:4];
+	
+	// Support for triggers wasn't added until MySQL 5.0.2
+	supportsTriggers = [self isEqualToOrGreaterThanMajorVersion:5 minor:0 release:2];
+	
+	// Support for specifying an index's key block size wasn't added until MySQL 5.1.10
+	supportsIndexKeyBlockSize = [self isEqualToOrGreaterThanMajorVersion:5 minor:1 release:10];	
+}
+
+/**
+ * Convenience method provided as an easy way to determine whether the currently connected server version
+ * is equal to or greater than the supplied version numbers. 
+ *
+ * This method should only be used in the case that the build in support ivars don't cover the version/functionality
+ * checking that is required.
+ *
+ * @param majorVersion   The major version number of the server
+ * @param minorVersion   The minor version number of the server
+ * @param releaseVersiod The release version number of the server
+ *
+ * @return A BOOL indicating the result of the comparison.
+ */
+- (BOOL)isEqualToOrGreaterThanMajorVersion:(NSInteger)majorVersion minor:(NSInteger)minorVersion release:(NSInteger)releaseVersion;
+{
+	return ([self _compareServerMajorVersion:serverMajorVersion 
+									   minor:serverMinorVersion 
+									 release:serverReleaseVersion 
+					  withServerMajorVersion:majorVersion 
+									   minor:minorVersion 
+									 release:releaseVersion] > NSOrderedAscending);
+}
+
+/**
+ * Provides a general description of this object instance. Note that this should only be used for debugging purposes.
+ *
+ * @return The string describing the object instance
+ */
+- (NSString *)description
+{
+	unsigned int i;
+	NSString *description = [NSMutableString stringWithFormat:@"<%@: Server is MySQL version %d.%d.%d. Supports:\n", [self className], serverMajorVersion, serverMinorVersion, serverReleaseVersion];
+	
+	Ivar *vars = class_copyIvarList([self class], &i);
+	
+	for (NSUInteger j = 0; j < i; j++) 
+	{	
+		NSString *varName = [NSString stringWithUTF8String:ivar_getName(vars[j])];
+		
+		if ([varName hasPrefix:@"supports"]) {
+			[description appendFormat:@"\t%@ = %@\n", varName, ((BOOL)object_getIvar(self, vars[j])) ? @"YES" : @"NO"];
+		}
+	}
+	
+	[description appendString:@">"];
+	
+	free(vars);
+	
+	return description;
+}
+
+#pragma mark -
+#pragma mark Private API
+
+/**
+ * Invalidates all knowledge of what we know the server supports by simply reseting all ivars to their
+ * original state, that is, it doesn't support anything.
+ */
+- (void)_invalidate
+{
+	isMySQL3                           = NO;
+	isMySQL4                           = NO;
+	isMySQL5                           = NO;
+	isMySQL6                           = NO;
+	
+	supportsInformationSchema          = NO;
+	supportsShowCharacterSet           = NO;
+	supportsCharacterSetDatabaseVar    = NO;
+	supportsPost41CharacterSetHandling = NO;
+	supportsCreateUser                 = NO;
+	supportsDropUser                   = NO;
+	supportsFullDropUser               = NO;
+	supportsUserMaxVars                = NO;
+	supportsShowPrivileges             = NO;
+	supportsInformationSchemaEngines   = NO;
+	supportsPre41StorageEngines        = NO;
+	supportsBlackholeStorageEngine     = NO;
+	supportsArchiveStorageEngine       = NO;
+	supportsCSVStorageEngine           = NO;
+	supportsTriggers                   = NO;
+	supportsIndexKeyBlockSize          = NO;
+}
+
+/**
+ * Compares the supplied version numbers to determine their order.
+ *
+ * Note that this method assumes (when comparing MySQL version numbers) that release verions in the form
+ * XX are larger than X. For example, version 5.0.18 is greater than version 5.0.8
+ *
+ * @param majorVersionA   The major version number of server A
+ * @param minorVersionA   The minor version number of server A
+ * @param releaseVersionA The release version number of server A
+ * @param majorVersionB   The major version number of server B
+ * @param minorVersionB   The minor version number of server B
+ * @param releaseVersionB The release version number of server B
+ *
+ * @return One of NSComparisonResult constants indicating the order of the comparison
+ */
+- (NSComparisonResult)_compareServerMajorVersion:(NSInteger)majorVersionA 
+										   minor:(NSInteger)minorVersionA 
+										 release:(NSInteger)releaseVersionA
+						  withServerMajorVersion:(NSInteger)majorVersionB
+										   minor:(NSInteger)minorVersionB
+										 release:(NSInteger)releaseVersionB
+{	
+	if (majorVersionA > majorVersionB) return NSOrderedDescending;
+
+	if (majorVersionA < majorVersionB) return NSOrderedAscending;
+	
+	// The major versions are the same so move to checking the minor versions
+	if (minorVersionA > minorVersionB) return NSOrderedDescending;
+	
+	if (minorVersionA < minorVersionB) return NSOrderedAscending;
+	
+	// The minor versions are the same so move to checking the release versions
+	if (releaseVersionA > releaseVersionB) return NSOrderedDescending;
+	
+	if (releaseVersionA < releaseVersionB) return NSOrderedAscending;
+	
+	// Both version numbers are the same
+	return NSOrderedSame;
+}
+
+#pragma mark -
+#pragma mark Other
+
+/**
+ * Dealloc. Invalidate all ivars.
+ */
+- (void)dealloc
+{
+	// Reset version integers
+	serverMajorVersion   = -1;
+	serverMinorVersion   = -1;
+	serverReleaseVersion = -1;
+	
+	// Invalidate all ivars
+	[self _invalidate];
+	
+	[super dealloc];
+}
+
+@end