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Wrap Lambda function in a struct to avoid crash in Mirror

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This commit is contained in:
Adam Fowler
2021-03-15 14:46:40 +00:00
parent 3559faac61
commit 978b14a96a
4 changed files with 86 additions and 24 deletions
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36
Sources/HummingbirdMustache/Lambda.swift
View File

@@ -1,2 +1,36 @@
public typealias HBMustacheLambda = (Any, HBMustacheTemplate) -> String
/// Lambda function. Can add this to object being rendered to filter contents of objects.
///
/// See http://mustache.github.io/mustache.5.html for more details on
/// mustache lambdas
/// e.g
/// ```
/// struct Object {
/// let name: String
/// let wrapped: HBMustacheLambda
/// }
/// let willy = Object(name: "Willy", wrapped: .init({ object, template in
/// return "<b>\(template.render(object))</b>"
/// }))
/// let mustache = "{{#wrapped}}{{name}} is awesome.{{/wrapped}}"
/// let template = try HBMustacheTemplate(string: mustache)
/// let output = template.render(willy)
/// print(output) // <b>Willy is awesome</b>
/// ```
///
public struct HBMustacheLambda {
/// lambda callback
public typealias Callback = (Any, HBMustacheTemplate) -> String
let callback: Callback
/// Initialize `HBMustacheLambda`
/// - Parameter cb: function to be called by lambda
public init(_ cb: @escaping Callback) {
self.callback = cb
}
internal func run(_ object: Any, _ template: HBMustacheTemplate) -> String {
return callback(object, template)
}
}

23
Sources/HummingbirdMustache/String.swift Normal file
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@@ -0,0 +1,23 @@
extension String {
private static let htmlEscapedCharacters: [Character: String] = [
"<": "&lt;",
">": "&gt;",
"&": "&amp;",
]
/// HTML escape string. Replace '<', '>' and '&' with HTML escaped versions
func htmlEscape() -> String {
var newString = ""
newString.reserveCapacity(self.count)
// currently doing this by going through each character could speed
// this us by treating as an array of UInt8's
for c in self {
if let replacement = Self.htmlEscapedCharacters[c] {
newString += replacement
} else {
newString.append(c)
}
}
return newString
}
}

49
Sources/HummingbirdMustache/Template+Render.swift
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@@ -1,5 +1,10 @@
extension HBMustacheTemplate {
/// Render template using object
/// - Parameters:
/// - object: Object
/// - context: Context that render is occurring in. Contains information about position in sequence
/// - Returns: Rendered text
func render(_ object: Any, context: HBMustacheContext? = nil) -> String {
var string = ""
for token in tokens {
@@ -11,7 +16,7 @@ extension HBMustacheTemplate {
if let template = child as? HBMustacheTemplate {
string += template.render(object)
} else {
string += htmlEscape(String(describing: child))
string += String(describing: child).htmlEscape()
}
}
case .unescapedVariable(let variable, let method):
@@ -34,7 +39,13 @@ extension HBMustacheTemplate {
}
return string
}
/// Render a section
/// - Parameters:
/// - child: Object to render section for
/// - parent: Current object being rendered
/// - template: Template to render with
/// - Returns: Rendered text
func renderSection(_ child: Any?, parent: Any, with template: HBMustacheTemplate) -> String {
switch child {
case let array as HBMustacheSequence:
@@ -42,7 +53,7 @@ extension HBMustacheTemplate {
case let bool as Bool:
return bool ? template.render(parent) : ""
case let lambda as HBMustacheLambda:
return lambda(parent, template)
return lambda.run(parent, template)
case .some(let value):
return template.render(value)
case .none:
@@ -50,6 +61,12 @@ extension HBMustacheTemplate {
}
}
/// Render an inverted section
/// - Parameters:
/// - child: Object to render section for
/// - parent: Current object being rendered
/// - template: Template to render with
/// - Returns: Rendered text
func renderInvertedSection(_ child: Any?, parent: Any, with template: HBMustacheTemplate) -> String {
switch child {
case let array as HBMustacheSequence:
@@ -62,7 +79,8 @@ extension HBMustacheTemplate {
return template.render(parent)
}
}
/// Get child object from variable name
func getChild(named name: String, from object: Any, method: String?, context: HBMustacheContext?) -> Any? {
func _getChild(named names: ArraySlice<String>, from object: Any) -> Any? {
guard let name = names.first else { return object }
@@ -78,6 +96,9 @@ extension HBMustacheTemplate {
return _getChild(named: names2, from: childObject!)
}
// work out which object to access. "." means the current object, if the variable name is ""
// and we have a method to run on the variable then we need the context object, otherwise
// the name is split by "." and we use mirror to get the correct child object
let child: Any?
if name == "." {
child = object
@@ -87,6 +108,8 @@ extension HBMustacheTemplate {
let nameSplit = name.split(separator: ".").map { String($0) }
child = _getChild(named: nameSplit[...], from: object)
}
// if we want to run a method and the current child can have methods applied to it then
// run method on the current child
if let method = method,
let runnable = child as? HBMustacheMethods {
if let result = runnable.runMethod(method) {
@@ -95,23 +118,5 @@ extension HBMustacheTemplate {
}
return child
}
private static let htmlEscapedCharacters: [Character: String] = [
"<": "&lt;",
">": "&gt;",
"&": "&amp;",
]
func htmlEscape(_ string: String) -> String {
var newString = ""
newString.reserveCapacity(string.count)
for c in string {
if let replacement = Self.htmlEscapedCharacters[c] {
newString += replacement
} else {
newString.append(c)
}
}
return newString
}
}

2
Tests/HummingbirdMustacheTests/TemplateRendererTests.swift
View File

@@ -166,7 +166,7 @@ final class TemplateRendererTests: XCTestCase {
func wrapped(object: Any, template: HBMustacheTemplate) -> String {
return "<b>\(template.render(object))</b>"
}
let object: [String: Any] = ["name": "Willy", "wrapped": wrapped]
let object: [String: Any] = ["name": "Willy", "wrapped": HBMustacheLambda(wrapped)]
XCTAssertEqual(template.render(object), """
<b>Willy is awesome.</b>
""")