feat: Add DictionaryLoader to load templates from dictionary

Closes #97

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 - Adds `counter0` to for loop context allowing you to get the current index of
   the for loop 0 indexed.
+- Introduces a new `DictionaryLoader` for loading templates from a Swift
+  Dictionary.
 
 ### Bug Fixes
 

Sources/Loader.swift

@@ -75,6 +75,33 @@ public class FileSystemLoader: Loader, CustomStringConvertible {
 }
 
 
+public class DictionaryLoader: Loader {
+  public let templates: [String: String]
+
+  public init(templates: [String: String]) {
+    self.templates = templates
+  }
+
+  public func loadTemplate(name: String, environment: Environment) throws -> Template {
+    if let content = templates[name] {
+      return environment.templateClass.init(templateString: content, environment: environment, name: name)
+    }
+
+    throw TemplateDoesNotExist(templateNames: [name], loader: self)
+  }
+
+  public func loadTemplate(names: [String], environment: Environment) throws -> Template {
+    for name in names {
+      if let content = templates[name] {
+        return environment.templateClass.init(templateString: content, environment: environment, name: name)
+      }
+    }
+
+    throw TemplateDoesNotExist(templateNames: names, loader: self)
+  }
+}
+
+
 extension Path {
   func safeJoin(path: Path) throws -> Path {
     let newPath = self + path

Tests/StencilTests/LoaderSpec.swift

@@ -29,4 +29,27 @@ func testTemplateLoader() {
       try expect(try environment.loadTemplate(name: "../LoaderSpec.swift")).toThrow()
     }
   }
+
+  describe("DictionaryLoader") {
+    let loader = DictionaryLoader(templates: [
+        "index.html": "Hello World"
+    ])
+    let environment = Environment(loader: loader)
+
+    $0.it("errors when a template cannot be found") {
+      try expect(try environment.loadTemplate(name: "unknown.html")).toThrow()
+    }
+
+    $0.it("errors when an array of templates cannot be found") {
+      try expect(try environment.loadTemplate(names: ["unknown.html", "unknown2.html"])).toThrow()
+    }
+
+    $0.it("can load a template from a known templates") {
+      _ = try environment.loadTemplate(name: "index.html")
+    }
+
+    $0.it("can load a known template from a collection of templates") {
+      _ = try environment.loadTemplate(names: ["unknown.html", "index.html"])
+    }
+  }
 }

docs/api.rst

@@ -73,6 +73,16 @@ on the file system.
     FileSystemLoader(bundle: [Bundle.main])
 
 
+DictionaryLoader
+~~~~~~~~~~~~~~~~
+
+Loads templates from a dictionary.
+
+.. code-block:: swift
+
+    DictionaryLoader(templates: ["index.html": "Hello World"])
+
+
 Custom Loaders
 ~~~~~~~~~~~~~~