107 lines
2.9 KiB
Swift
107 lines
2.9 KiB
Swift
/// A container for template variables.
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public class Context {
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var dictionaries: [[String: Any?]]
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/// The context's environment, such as registered extensions, classes, …
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public let environment: Environment
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init(dictionaries: [[String: Any?]], environment: Environment) {
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self.dictionaries = dictionaries
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self.environment = environment
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}
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/// Create a context from a dictionary (and an env.)
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///
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/// - Parameters:
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/// - dictionary: The context's data
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/// - environment: Environment such as extensions, …
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public convenience init(dictionary: [String: Any] = [:], environment: Environment? = nil) {
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self.init(
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dictionaries: dictionary.isEmpty ? [] : [dictionary],
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environment: environment ?? Environment()
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)
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}
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/// Access variables in this context by name
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public subscript(key: String) -> Any? {
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/// Retrieves a variable's value, starting at the current context and going upwards
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get {
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for dictionary in Array(dictionaries.reversed()) {
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if let value = dictionary[key] {
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return value
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}
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}
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return nil
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}
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/// Set a variable in the current context, deleting the variable if it's nil
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set(value) {
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if var dictionary = dictionaries.popLast() {
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dictionary[key] = value
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dictionaries.append(dictionary)
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}
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}
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}
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/// Push a new level into the Context
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///
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/// - Parameters:
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/// - dictionary: The new level data
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fileprivate func push(_ dictionary: [String: Any] = [:]) {
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dictionaries.append(dictionary)
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}
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/// Pop the last level off of the Context
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///
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/// - returns: The popped level
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// swiftlint:disable:next discouraged_optional_collection
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fileprivate func pop() -> [String: Any?]? {
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dictionaries.popLast()
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}
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/// Push a new level onto the context for the duration of the execution of the given closure
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///
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/// - Parameters:
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/// - dictionary: The new level data
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/// - closure: The closure to execute
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/// - returns: Return value of the closure
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public func push<Result>(dictionary: [String: Any] = [:], closure: (() throws -> Result)) rethrows -> Result {
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push(dictionary)
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defer { _ = pop() }
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return try closure()
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}
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/// Flatten all levels of context data into 1, merging duplicate variables
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///
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/// - returns: All collected variables
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public func flatten() -> [String: Any] {
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var accumulator: [String: Any] = [:]
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for dictionary in dictionaries {
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for (key, value) in dictionary {
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if let value = value {
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accumulator.updateValue(value, forKey: key)
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}
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}
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}
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return accumulator
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}
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/// Cache result of block by its name in the context top-level, so that it can be later rendered
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/// via `{{ block.name }}`
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///
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/// - Parameters:
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/// - name: The name of the stored block
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/// - content: The block's rendered content
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public func cacheBlock(_ name: String, content: String) {
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if var block = dictionaries.first?["block"] as? [String: String] {
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block[name] = content
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dictionaries[0]["block"] = block
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} else {
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dictionaries.insert(["block": [name: content]], at: 0)
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}
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}
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}
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