69 lines
1.7 KiB
Swift
69 lines
1.7 KiB
Swift
/// A container for template variables.
|
|
public class Context {
|
|
var dictionaries: [[String: Any?]]
|
|
|
|
public let environment: Environment
|
|
|
|
init(dictionary: [String: Any] = [:], environment: Environment? = nil) {
|
|
if !dictionary.isEmpty {
|
|
dictionaries = [dictionary]
|
|
} else {
|
|
dictionaries = []
|
|
}
|
|
|
|
self.environment = environment ?? Environment()
|
|
}
|
|
|
|
public subscript(key: String) -> Any? {
|
|
/// Retrieves a variable's value, starting at the current context and going upwards
|
|
get {
|
|
for dictionary in Array(dictionaries.reversed()) {
|
|
if let value = dictionary[key] {
|
|
return value
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
/// Set a variable in the current context, deleting the variable if it's nil
|
|
set(value) {
|
|
if var dictionary = dictionaries.popLast() {
|
|
dictionary[key] = value
|
|
dictionaries.append(dictionary)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Push a new level into the Context
|
|
fileprivate func push(_ dictionary: [String: Any] = [:]) {
|
|
dictionaries.append(dictionary)
|
|
}
|
|
|
|
/// Pop the last level off of the Context
|
|
fileprivate func pop() -> [String: Any?]? {
|
|
return dictionaries.popLast()
|
|
}
|
|
|
|
/// Push a new level onto the context for the duration of the execution of the given closure
|
|
public func push<Result>(dictionary: [String: Any] = [:], closure: (() throws -> Result)) rethrows -> Result {
|
|
push(dictionary)
|
|
defer { _ = pop() }
|
|
return try closure()
|
|
}
|
|
|
|
public func flatten() -> [String: Any] {
|
|
var accumulator: [String: Any] = [:]
|
|
|
|
for dictionary in dictionaries {
|
|
for (key, value) in dictionary {
|
|
if let value = value {
|
|
accumulator.updateValue(value, forKey: key)
|
|
}
|
|
}
|
|
}
|
|
|
|
return accumulator
|
|
}
|
|
}
|