refactor(if): Move expressions to separate file

Sources/Expression.swift

@@ -0,0 +1,136 @@
+protocol Expression: CustomStringConvertible {
+  func evaluate(context: Context) throws -> Bool
+}
+
+
+protocol InfixOperator: Expression {
+  init(lhs: Expression, rhs: Expression)
+}
+
+
+protocol PrefixOperator: Expression {
+  init(expression: Expression)
+}
+
+
+final class StaticExpression: Expression, CustomStringConvertible {
+  let value: Bool
+
+  init(value: Bool) {
+    self.value = value
+  }
+
+  func evaluate(context: Context) throws -> Bool {
+    return value
+  }
+
+  var description: String {
+    return "\(value)"
+  }
+}
+
+
+final class VariableExpression: Expression, CustomStringConvertible {
+  let variable: Variable
+
+  init(variable: Variable) {
+    self.variable = variable
+  }
+
+  var description: String {
+    return "(variable: \(variable.variable))"
+  }
+
+  /// Resolves a variable in the given context as boolean
+  func resolve(context: Context, variable: Variable) throws -> Bool {
+    let result = try variable.resolve(context)
+    var truthy = false
+
+    if let result = result as? [Any] {
+      truthy = !result.isEmpty
+    } else if let result = result as? [String:Any] {
+      truthy = !result.isEmpty
+    } else if let result = result as? Bool {
+      truthy = result
+    } else if let result = result as? Int {
+      truthy = result > 0
+    } else if let result = result as? Float {
+      truthy = result > 0
+    } else if let result = result as? Double {
+      truthy = result > 0
+    } else if result != nil {
+      truthy = true
+    }
+
+    return truthy
+  }
+
+  func evaluate(context: Context) throws -> Bool {
+    return try resolve(context: context, variable: variable)
+  }
+}
+
+
+final class NotExpression: Expression, PrefixOperator, CustomStringConvertible {
+  let expression: Expression
+
+  init(expression: Expression) {
+    self.expression = expression
+  }
+
+  var description: String {
+    return "not \(expression)"
+  }
+
+  func evaluate(context: Context) throws -> Bool {
+    return try !expression.evaluate(context: context)
+  }
+}
+
+
+final class OrExpression: Expression, InfixOperator, CustomStringConvertible {
+  let lhs: Expression
+  let rhs: Expression
+
+  init(lhs: Expression, rhs: Expression) {
+    self.lhs = lhs
+    self.rhs = rhs
+  }
+
+  var description: String {
+    return "(\(lhs) or \(rhs))"
+  }
+
+  func evaluate(context: Context) throws -> Bool {
+    let lhs = try self.lhs.evaluate(context: context)
+    if lhs {
+      return lhs
+    }
+
+    return try rhs.evaluate(context: context)
+  }
+}
+
+
+final class AndExpression: Expression, InfixOperator, CustomStringConvertible {
+  let lhs: Expression
+  let rhs: Expression
+
+  init(lhs: Expression, rhs: Expression) {
+    self.lhs = lhs
+    self.rhs = rhs
+  }
+
+  var description: String {
+    return "(\(lhs) and \(rhs))"
+  }
+
+  func evaluate(context: Context) throws -> Bool {
+    let lhs = try self.lhs.evaluate(context: context)
+    if !lhs {
+      return lhs
+    }
+
+    return try rhs.evaluate(context: context)
+  }
+}

Sources/IfTag.swift

@@ -1,141 +1,3 @@
-protocol Expression: CustomStringConvertible {
-  func evaluate(context: Context) throws -> Bool
-}
-
-
-protocol InfixOperator: Expression {
-  init(lhs: Expression, rhs: Expression)
-}
-
-
-protocol PrefixOperator: Expression {
-  init(expression: Expression)
-}
-
-
-final class StaticExpression: Expression, CustomStringConvertible {
-  let value: Bool
-
-  init(value: Bool) {
-    self.value = value
-  }
-
-  func evaluate(context: Context) throws -> Bool {
-    return value
-  }
-
-  var description: String {
-    return "\(value)"
-  }
-}
-
-
-final class VariableExpression: Expression, CustomStringConvertible {
-  let variable: Variable
-
-  init(variable: Variable) {
-    self.variable = variable
-  }
-
-  var description: String {
-    return "(variable: \(variable.variable))"
-  }
-
-  /// Resolves a variable in the given context as boolean
-  func resolve(context: Context, variable: Variable) throws -> Bool {
-    let result = try variable.resolve(context)
-    var truthy = false
-
-    if let result = result as? [Any] {
-      truthy = !result.isEmpty
-    } else if let result = result as? [String:Any] {
-      truthy = !result.isEmpty
-    } else if let result = result as? Bool {
-      truthy = result
-    } else if let result = result as? Int {
-      truthy = result > 0
-    } else if let result = result as? Float {
-      truthy = result > 0
-    } else if let result = result as? Double {
-      truthy = result > 0
-    } else if result != nil {
-      truthy = true
-    }
-
-    return truthy
-  }
-
-  func evaluate(context: Context) throws -> Bool {
-    return try resolve(context: context, variable: variable)
-  }
-}
-
-
-final class NotExpression: Expression, PrefixOperator, CustomStringConvertible {
-  let expression: Expression
-
-  init(expression: Expression) {
-    self.expression = expression
-  }
-
-  var description: String {
-    return "not \(expression)"
-  }
-
-  func evaluate(context: Context) throws -> Bool {
-    return try !expression.evaluate(context: context)
-  }
-}
-
-
-final class OrExpression: Expression, InfixOperator, CustomStringConvertible {
-  let lhs: Expression
-  let rhs: Expression
-
-  init(lhs: Expression, rhs: Expression) {
-    self.lhs = lhs
-    self.rhs = rhs
-  }
-
-  var description: String {
-    return "(\(lhs) or \(rhs))"
-  }
-
-  func evaluate(context: Context) throws -> Bool {
-    let lhs = try self.lhs.evaluate(context: context)
-    if lhs {
-      return lhs
-    }
-
-    return try rhs.evaluate(context: context)
-  }
-}
-
-
-final class AndExpression: Expression, InfixOperator, CustomStringConvertible {
-  let lhs: Expression
-  let rhs: Expression
-
-  init(lhs: Expression, rhs: Expression) {
-    self.lhs = lhs
-    self.rhs = rhs
-  }
-
-  var description: String {
-    return "(\(lhs) and \(rhs))"
-  }
-
-  func evaluate(context: Context) throws -> Bool {
-    let lhs = try self.lhs.evaluate(context: context)
-    if !lhs {
-      return lhs
-    }
-
-    return try rhs.evaluate(context: context)
-  }
-}
-
-
 enum Operator {
   case infix(String, Int, InfixOperator.Type)
   case prefix(String, Int, PrefixOperator.Type)