refactor(if): Move expressions to separate file
This commit is contained in:
Kyle Fuller
136
Sources/Expression.swift
Normal file
136
Sources/Expression.swift
Normal file
@@ -0,0 +1,136 @@
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protocol Expression: CustomStringConvertible {
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func evaluate(context: Context) throws -> Bool
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}
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protocol InfixOperator: Expression {
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init(lhs: Expression, rhs: Expression)
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}
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protocol PrefixOperator: Expression {
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init(expression: Expression)
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}
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final class StaticExpression: Expression, CustomStringConvertible {
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let value: Bool
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init(value: Bool) {
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self.value = value
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}
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func evaluate(context: Context) throws -> Bool {
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return value
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}
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var description: String {
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return "\(value)"
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}
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}
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final class VariableExpression: Expression, CustomStringConvertible {
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let variable: Variable
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init(variable: Variable) {
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self.variable = variable
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}
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var description: String {
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return "(variable: \(variable.variable))"
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}
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/// Resolves a variable in the given context as boolean
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func resolve(context: Context, variable: Variable) throws -> Bool {
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let result = try variable.resolve(context)
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var truthy = false
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if let result = result as? [Any] {
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truthy = !result.isEmpty
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} else if let result = result as? [String:Any] {
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truthy = !result.isEmpty
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} else if let result = result as? Bool {
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truthy = result
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} else if let result = result as? Int {
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truthy = result > 0
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} else if let result = result as? Float {
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truthy = result > 0
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} else if let result = result as? Double {
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truthy = result > 0
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} else if result != nil {
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truthy = true
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}
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return truthy
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}
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func evaluate(context: Context) throws -> Bool {
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return try resolve(context: context, variable: variable)
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}
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}
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final class NotExpression: Expression, PrefixOperator, CustomStringConvertible {
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let expression: Expression
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init(expression: Expression) {
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self.expression = expression
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}
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var description: String {
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return "not \(expression)"
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}
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func evaluate(context: Context) throws -> Bool {
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return try !expression.evaluate(context: context)
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}
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}
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final class OrExpression: Expression, InfixOperator, CustomStringConvertible {
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let lhs: Expression
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let rhs: Expression
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init(lhs: Expression, rhs: Expression) {
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self.lhs = lhs
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self.rhs = rhs
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}
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var description: String {
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return "(\(lhs) or \(rhs))"
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}
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func evaluate(context: Context) throws -> Bool {
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let lhs = try self.lhs.evaluate(context: context)
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if lhs {
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return lhs
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}
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return try rhs.evaluate(context: context)
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}
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}
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final class AndExpression: Expression, InfixOperator, CustomStringConvertible {
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let lhs: Expression
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let rhs: Expression
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init(lhs: Expression, rhs: Expression) {
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self.lhs = lhs
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self.rhs = rhs
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}
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var description: String {
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return "(\(lhs) and \(rhs))"
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}
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func evaluate(context: Context) throws -> Bool {
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let lhs = try self.lhs.evaluate(context: context)
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if !lhs {
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return lhs
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}
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return try rhs.evaluate(context: context)
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}
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}
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@@ -1,141 +1,3 @@
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protocol Expression: CustomStringConvertible {
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func evaluate(context: Context) throws -> Bool
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}
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protocol InfixOperator: Expression {
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init(lhs: Expression, rhs: Expression)
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}
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protocol PrefixOperator: Expression {
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init(expression: Expression)
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}
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final class StaticExpression: Expression, CustomStringConvertible {
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let value: Bool
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init(value: Bool) {
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self.value = value
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}
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func evaluate(context: Context) throws -> Bool {
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return value
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}
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var description: String {
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return "\(value)"
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}
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}
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final class VariableExpression: Expression, CustomStringConvertible {
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let variable: Variable
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init(variable: Variable) {
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self.variable = variable
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}
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var description: String {
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return "(variable: \(variable.variable))"
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}
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/// Resolves a variable in the given context as boolean
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func resolve(context: Context, variable: Variable) throws -> Bool {
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let result = try variable.resolve(context)
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var truthy = false
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if let result = result as? [Any] {
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truthy = !result.isEmpty
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} else if let result = result as? [String:Any] {
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truthy = !result.isEmpty
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} else if let result = result as? Bool {
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truthy = result
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} else if let result = result as? Int {
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truthy = result > 0
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} else if let result = result as? Float {
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truthy = result > 0
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} else if let result = result as? Double {
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truthy = result > 0
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} else if result != nil {
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truthy = true
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}
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return truthy
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}
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func evaluate(context: Context) throws -> Bool {
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return try resolve(context: context, variable: variable)
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}
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}
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final class NotExpression: Expression, PrefixOperator, CustomStringConvertible {
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let expression: Expression
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init(expression: Expression) {
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self.expression = expression
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}
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var description: String {
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return "not \(expression)"
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}
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func evaluate(context: Context) throws -> Bool {
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return try !expression.evaluate(context: context)
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}
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}
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final class OrExpression: Expression, InfixOperator, CustomStringConvertible {
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let lhs: Expression
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let rhs: Expression
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init(lhs: Expression, rhs: Expression) {
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self.lhs = lhs
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self.rhs = rhs
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}
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var description: String {
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return "(\(lhs) or \(rhs))"
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}
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func evaluate(context: Context) throws -> Bool {
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let lhs = try self.lhs.evaluate(context: context)
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if lhs {
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return lhs
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}
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return try rhs.evaluate(context: context)
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}
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}
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final class AndExpression: Expression, InfixOperator, CustomStringConvertible {
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let lhs: Expression
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let rhs: Expression
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init(lhs: Expression, rhs: Expression) {
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self.lhs = lhs
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self.rhs = rhs
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}
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var description: String {
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return "(\(lhs) and \(rhs))"
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}
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func evaluate(context: Context) throws -> Bool {
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let lhs = try self.lhs.evaluate(context: context)
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if !lhs {
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return lhs
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}
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return try rhs.evaluate(context: context)
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}
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}
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enum Operator {
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case infix(String, Int, InfixOperator.Type)
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case prefix(String, Int, PrefixOperator.Type)
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171
Tests/StencilTests/ExpressionSpec.swift
Normal file
171
Tests/StencilTests/ExpressionSpec.swift
Normal file
@@ -0,0 +1,171 @@
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import Spectre
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@testable import Stencil
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func testExpressions() {
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describe("Expression") {
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$0.describe("VariableExpression") {
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let expression = VariableExpression(variable: Variable("value"))
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$0.it("evaluates to true when value is not nil") {
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let context = Context(dictionary: ["value": "known"])
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try expect(try expression.evaluate(context: context)).to.beTrue()
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}
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$0.it("evaluates to false when value is unset") {
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let context = Context()
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try expect(try expression.evaluate(context: context)).to.beFalse()
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}
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$0.it("evaluates to true when array variable is not empty") {
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let items: [[String: Any]] = [["key":"key1","value":42],["key":"key2","value":1337]]
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let context = Context(dictionary: ["value": [items]])
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try expect(try expression.evaluate(context: context)).to.beTrue()
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}
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$0.it("evaluates to false when array value is empty") {
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let emptyItems = [[String: Any]]()
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let context = Context(dictionary: ["value": emptyItems])
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try expect(try expression.evaluate(context: context)).to.beFalse()
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}
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$0.it("evaluates to false when dictionary value is empty") {
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let emptyItems = [String:Any]()
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let context = Context(dictionary: ["value": emptyItems])
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try expect(try expression.evaluate(context: context)).to.beFalse()
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}
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$0.it("evaluates to false when Array<Any> value is empty") {
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let context = Context(dictionary: ["value": ([] as [Any])])
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try expect(try expression.evaluate(context: context)).to.beFalse()
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}
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$0.it("evaluates to true when integer value is above 0") {
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let context = Context(dictionary: ["value": 1])
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try expect(try expression.evaluate(context: context)).to.beTrue()
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}
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$0.it("evaluates to false when integer value is below 0 or below") {
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let context = Context(dictionary: ["value": 0])
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try expect(try expression.evaluate(context: context)).to.beFalse()
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let negativeContext = Context(dictionary: ["value": 0])
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try expect(try expression.evaluate(context: negativeContext)).to.beFalse()
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}
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$0.it("evaluates to true when float value is above 0") {
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let context = Context(dictionary: ["value": Float(0.5)])
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try expect(try expression.evaluate(context: context)).to.beTrue()
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}
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$0.it("evaluates to false when float is 0 or below") {
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let context = Context(dictionary: ["value": Float(0)])
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try expect(try expression.evaluate(context: context)).to.beFalse()
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}
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$0.it("evaluates to true when double value is above 0") {
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let context = Context(dictionary: ["value": Double(0.5)])
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try expect(try expression.evaluate(context: context)).to.beTrue()
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}
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$0.it("evaluates to false when double is 0 or below") {
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let context = Context(dictionary: ["value": Double(0)])
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try expect(try expression.evaluate(context: context)).to.beFalse()
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}
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}
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$0.describe("NotExpression") {
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$0.it("returns truthy for positive expressions") {
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let expression = NotExpression(expression: StaticExpression(value: true))
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try expect(expression.evaluate(context: Context())).to.beFalse()
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}
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$0.it("returns falsy for negative expressions") {
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let expression = NotExpression(expression: StaticExpression(value: false))
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try expect(expression.evaluate(context: Context())).to.beTrue()
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}
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}
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$0.describe("expression parsing") {
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$0.it("can parse a variable expression") {
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let expression = try parseExpression(components: ["value"])
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try expect(expression.evaluate(context: Context())).to.beFalse()
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try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beTrue()
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}
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$0.it("can parse a not expression") {
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let expression = try parseExpression(components: ["not", "value"])
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try expect(expression.evaluate(context: Context())).to.beTrue()
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try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beFalse()
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}
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$0.describe("and expression") {
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let expression = try! parseExpression(components: ["lhs", "and", "rhs"])
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$0.it("evaluates to false with lhs false") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beFalse()
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}
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$0.it("evaluates to false with rhs false") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beFalse()
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}
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$0.it("evaluates to false with lhs and rhs false") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
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}
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$0.it("evaluates to true with lhs and rhs true") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
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}
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}
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$0.describe("or expression") {
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let expression = try! parseExpression(components: ["lhs", "or", "rhs"])
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$0.it("evaluates to true with lhs true") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beTrue()
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}
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$0.it("evaluates to true with rhs true") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beTrue()
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}
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$0.it("evaluates to true with lhs and rhs true") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
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}
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$0.it("evaluates to false with lhs and rhs false") {
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try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
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}
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}
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$0.describe("multiple expression") {
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let expression = try! parseExpression(components: ["one", "or", "two", "and", "not", "three"])
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$0.it("evaluates to true with one") {
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try expect(expression.evaluate(context: Context(dictionary: ["one": true]))).to.beTrue()
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}
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$0.it("evaluates to true with one and three") {
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try expect(expression.evaluate(context: Context(dictionary: ["one": true, "three": true]))).to.beTrue()
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}
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$0.it("evaluates to true with two") {
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try expect(expression.evaluate(context: Context(dictionary: ["two": true]))).to.beTrue()
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}
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$0.it("evaluates to false with two and three") {
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try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
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}
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$0.it("evaluates to false with two and three") {
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try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
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}
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$0.it("evaluates to false with nothing") {
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try expect(expression.evaluate(context: Context())).to.beFalse()
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}
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}
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}
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}
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}
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@@ -12,12 +12,12 @@ public func stencilTests() {
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testVariable()
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testNode()
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testForNode()
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testExpressions()
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testIfNode()
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testNowNode()
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testInclude()
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testInheritence()
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testStencil()
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}
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Block a user