Move modules to Modules folder.

Modules/RSDatabase/Sources/RSDatabaseObjC/NSString+RSDatabase.m

@@ -0,0 +1,135 @@
+//
+//  NSString+RSDatabase.m
+//	RSDatabase
+//
+//  Created by Brent Simmons on 3/27/15.
+//  Copyright (c) 2015 Ranchero Software, LLC. All rights reserved.
+//
+
+#import "NSString+RSDatabase.h"
+
+
+@implementation NSString (RSDatabase)
+
+
++ (NSString *)rs_SQLValueListWithPlaceholders:(NSUInteger)numberOfValues {
+
+	// @"(?, ?, ?)"
+
+	NSParameterAssert(numberOfValues > 0);
+	if (numberOfValues < 1) {
+		return nil;
+	}
+
+	static NSMutableDictionary *cache = nil;
+	static dispatch_once_t onceToken;
+	static NSLock *lock = nil;
+	dispatch_once(&onceToken, ^{
+		lock = [[NSLock alloc] init];
+		cache = [NSMutableDictionary new];
+	});
+
+	[lock lock];
+	NSNumber *cacheKey = @(numberOfValues);
+	NSString *cachedString = cache[cacheKey];
+	if (cachedString) {
+		[lock unlock];
+		return cachedString;
+	}
+
+	NSMutableString *s = [[NSMutableString alloc] initWithString:@"("];
+	NSUInteger i = 0;
+
+	for (i = 0; i < numberOfValues; i++) {
+
+		[s appendString:@"?"];
+		BOOL isLast = (i == (numberOfValues - 1));
+		if (!isLast) {
+			[s appendString:@", "];
+		}
+	}
+
+	[s appendString:@")"];
+	
+	cache[cacheKey] = s;
+	[lock unlock];
+
+	return s;
+}
+
+
++ (NSString *)rs_SQLKeysListWithArray:(NSArray *)keys {
+
+	NSParameterAssert(keys.count > 0);
+
+	static NSMutableDictionary *cache = nil;
+	static dispatch_once_t onceToken;
+	static NSLock *lock = nil;
+	dispatch_once(&onceToken, ^{
+		lock = [[NSLock alloc] init];
+		cache = [NSMutableDictionary new];
+	});
+
+	[lock lock];
+	NSArray *cacheKey = keys;
+	NSString *cachedString = cache[cacheKey];
+	if (cachedString) {
+		[lock unlock];
+		return cachedString;
+	}
+	
+	NSString *s = [NSString stringWithFormat:@"(%@)", [keys componentsJoinedByString:@", "]];
+
+	cache[cacheKey] = s;
+	[lock unlock];
+
+	return s;
+}
+
+
++ (NSString *)rs_SQLKeyPlaceholderPairsWithKeys:(NSArray *)keys {
+
+	// key1=?, key2=?
+
+	NSParameterAssert(keys.count > 0);
+	
+	static NSMutableDictionary *cache = nil;
+	static dispatch_once_t onceToken;
+	static NSLock *lock = nil;
+	dispatch_once(&onceToken, ^{
+		lock = [[NSLock alloc] init];
+		cache = [NSMutableDictionary new];
+	});
+
+	[lock lock];
+	NSArray *cacheKey = keys;
+	NSString *cachedString = cache[cacheKey];
+	if (cachedString) {
+		[lock unlock];
+		return cachedString;
+	}
+	
+	NSMutableString *s = [NSMutableString stringWithString:@""];
+
+	NSUInteger i = 0;
+	NSUInteger numberOfKeys = [keys count];
+
+	for (i = 0; i < numberOfKeys; i++) {
+
+		NSString *oneKey = keys[i];
+		[s appendString:oneKey];
+		[s appendString:@"=?"];
+		BOOL isLast = (i == (numberOfKeys - 1));
+		if (!isLast) {
+			[s appendString:@", "];
+		}
+	}
+
+	cache[cacheKey] = s;
+	[lock unlock];
+
+	return s;
+}
+
+
+@end