feat: Added indent filter (#188)

CHANGELOG.md

@@ -10,6 +10,7 @@
 - Added `split` filter
 - Allow default string filters to be applied to arrays
 - Similar filters are suggested when unknown filter is used
+- Added `indent` filter
 
 ### Bug Fixes
 

Sources/Extension.swift

@@ -58,6 +58,7 @@ class DefaultExtension: Extension {
     registerFilter("lowercase", filter: lowercase)
     registerFilter("join", filter: joinFilter)
     registerFilter("split", filter: splitFilter)
+    registerFilter("indent", filter: indentFilter)
   }
 }
 

Sources/Filters.swift

@@ -65,3 +65,49 @@ func splitFilter(value: Any?, arguments: [Any?]) throws -> Any? {
 
   return value
 }
+
+func indentFilter(value: Any?, arguments: [Any?]) throws -> Any? {
+  guard arguments.count <= 3 else {
+    throw TemplateSyntaxError("'indent' filter can take at most 3 arguments")
+  }
+
+  var indentWidth = 4
+  if arguments.count > 0 {
+    guard let value = arguments[0] as? Int else {
+      throw TemplateSyntaxError("'indent' filter width argument must be an Integer (\(String(describing: arguments[0])))")
+    }
+    indentWidth = value
+  }
+
+  var indentationChar = " "
+  if arguments.count > 1 {
+    guard let value = arguments[1] as? String else {
+      throw TemplateSyntaxError("'indent' filter indentation argument must be a String (\(String(describing: arguments[1]))")
+    }
+    indentationChar = value
+  }
+
+  var indentFirst = false
+  if arguments.count > 2 {
+    guard let value = arguments[2] as? Bool else {
+      throw TemplateSyntaxError("'indent' filter indentFirst argument must be a Bool")
+    }
+    indentFirst = value
+  }
+
+  let indentation = [String](repeating: indentationChar, count: indentWidth).joined(separator: "")
+  return indent(stringify(value), indentation: indentation, indentFirst: indentFirst)
+}
+
+
+func indent(_ content: String, indentation: String, indentFirst: Bool) -> String {
+  guard !indentation.isEmpty else { return content }
+
+  var lines = content.components(separatedBy: .newlines)
+  let firstLine = (indentFirst ? indentation : "") + lines.removeFirst()
+  let result = lines.reduce([firstLine]) { (result, line) in
+    return result + [(line.isEmpty ? "" : "\(indentation)\(line)")]
+  }
+  return result.joined(separator: "\n")
+}
+

Sources/Variable.swift

@@ -70,6 +70,10 @@ public struct Variable : Equatable, Resolvable {
     if let number = Number(variable) {
       return number
     }
+    // Boolean literal
+    if let bool = Bool(variable) {
+      return bool
+    }
 
     for bit in lookup() {
       current = normalize(current)

Tests/StencilTests/FilterSpec.swift

@@ -244,4 +244,30 @@ func testFilter() {
 
   }
 
+
+  describe("indent filter") {
+    $0.it("indents content") {
+      let template = Template(templateString: "{{ value|indent:2 }}")
+      let result = try template.render(Context(dictionary: ["value": "One\nTwo"]))
+      try expect(result) == "One\n  Two"
+    }
+
+    $0.it("can indent with arbitrary character") {
+      let template = Template(templateString: "{{ value|indent:2,\"\t\" }}")
+      let result = try template.render(Context(dictionary: ["value": "One\nTwo"]))
+      try expect(result) == "One\n\t\tTwo"
+    }
+
+    $0.it("can indent first line") {
+      let template = Template(templateString: "{{ value|indent:2,\" \",true }}")
+      let result = try template.render(Context(dictionary: ["value": "One\nTwo"]))
+      try expect(result) == "  One\n  Two"
+    }
+
+    $0.it("does not indent empty lines") {
+      let template = Template(templateString: "{{ value|indent }}")
+      let result = try template.render(Context(dictionary: ["value": "One\n\n\nTwo\n\n"]))
+      try expect(result) == "One\n\n\n    Two\n\n"
+    }
+  }
 }

Tests/StencilTests/FilterTagSpec.swift

@@ -21,5 +21,14 @@ func testFilterTag() {
       try expect(try template.render()).toThrow()
     }
 
+    $0.it("can render filters with arguments") {
+      let ext = Extension()
+      ext.registerFilter("split", filter: {
+        return ($0 as! String).components(separatedBy: $1[0] as! String)
+      })
+      let env = Environment(extensions: [ext])
+      let result = try env.renderTemplate(string: "{% filter split:\",\"|join:\";\"  %}{{ items|join:\",\" }}{% endfilter %}", context: ["items": [1, 2]])
+      try expect(result) == "1;2"
+    }
   }
 }

Tests/StencilTests/VariableSpec.swift

@@ -71,6 +71,13 @@ func testVariable() {
       try expect(result) == 3.14
     }
 
+    $0.it("can resolve boolean literal") {
+      try expect(Variable("true").resolve(context) as? Bool) == true
+      try expect(Variable("false").resolve(context) as? Bool) == false
+      try expect(Variable("0").resolve(context) as? Int) == 0
+      try expect(Variable("1").resolve(context) as? Int) == 1
+    }
+
     $0.it("can resolve a string variable") {
       let variable = Variable("name")
       let result = try variable.resolve(context) as? String