language: introduce the requirement to use return to return a value from a function

ast/src/main/ast/pork.yml

@@ -300,6 +300,11 @@ types:
   Continue:
     parent: Expression
     values: []
+  Return:
+    parent: Expression
+    values:
+    - name: value
+      type: Expression
   NoneLiteral:
     parent: Expression
     values: []

ast/src/main/graph/types.dot

@@ -36,6 +36,7 @@ digraph A {
   type_ForIn [shape=box,label="ForIn"]
   type_Break [shape=box,label="Break"]
   type_Continue [shape=box,label="Continue"]
+  type_Return [shape=box,label="Return"]
   type_NoneLiteral [shape=box,label="NoneLiteral"]
   type_NativeFunctionDescriptor [shape=box,label="NativeFunctionDescriptor"]
   type_IndexedBy [shape=box,label="IndexedBy"]
@@ -69,6 +70,7 @@ digraph A {
   type_Expression -> type_ForIn
   type_Expression -> type_Break
   type_Expression -> type_Continue
+  type_Expression -> type_Return
   type_Expression -> type_NoneLiteral
   type_Expression -> type_IndexedBy
   type_Definition -> type_FunctionDefinition
@@ -116,6 +118,7 @@ digraph A {
   type_ForIn -> type_ForInItem [style=dotted]
   type_ForIn -> type_Expression [style=dotted]
   type_ForIn -> type_Block [style=dotted]
+  type_Return -> type_Expression [style=dotted]
   type_NativeFunctionDescriptor -> type_Symbol [style=dotted]
   type_NativeFunctionDescriptor -> type_StringLiteral [style=dotted]
   type_IndexedBy -> type_Expression [style=dotted]

ast/src/main/kotlin/gay/pizza/pork/ast/gen/NodeCoalescer.kt

@@ -77,6 +77,9 @@ class NodeCoalescer(val followChildren: Boolean = true, val handler: (Node) -> U
   override fun visitPrefixOperation(node: PrefixOperation): Unit =
     handle(node)
 
+  override fun visitReturn(node: Return): Unit =
+    handle(node)
+
   override fun visitSetAssignment(node: SetAssignment): Unit =
     handle(node)
 

ast/src/main/kotlin/gay/pizza/pork/ast/gen/NodeParser.kt

@@ -58,6 +58,8 @@ interface NodeParser {
 
   fun parsePrefixOperation(): PrefixOperation
 
+  fun parseReturn(): Return
+
   fun parseSetAssignment(): SetAssignment
 
   fun parseStringLiteral(): StringLiteral

ast/src/main/kotlin/gay/pizza/pork/ast/gen/NodeParserExtensions.kt

@@ -35,6 +35,7 @@ fun NodeParser.parse(type: NodeType): Node =
     NodeType.ForIn -> parseForIn()
     NodeType.Break -> parseBreak()
     NodeType.Continue -> parseContinue()
+    NodeType.Return -> parseReturn()
     NodeType.NoneLiteral -> parseNoneLiteral()
     NodeType.NativeFunctionDescriptor -> parseNativeFunctionDescriptor()
     NodeType.IndexedBy -> parseIndexedBy()

ast/src/main/kotlin/gay/pizza/pork/ast/gen/NodeType.kt

@@ -31,6 +31,7 @@ enum class NodeType(val parent: NodeType? = null) {
   NoneLiteral(Expression),
   Parentheses(Expression),
   PrefixOperation(Expression),
+  Return(Expression),
   SetAssignment(Expression),
   StringLiteral(Expression),
   SuffixOperation(Expression),

ast/src/main/kotlin/gay/pizza/pork/ast/gen/NodeVisitor.kt

@@ -52,6 +52,8 @@ interface NodeVisitor<T> {
 
   fun visitPrefixOperation(node: PrefixOperation): T
 
+  fun visitReturn(node: Return): T
+
   fun visitSetAssignment(node: SetAssignment): T
 
   fun visitStringLiteral(node: StringLiteral): T

ast/src/main/kotlin/gay/pizza/pork/ast/gen/NodeVisitorExtensions.kt

@@ -32,6 +32,7 @@ fun <T> NodeVisitor<T>.visit(node: Node): T =
     is ForIn -> visitForIn(node)
     is Break -> visitBreak(node)
     is Continue -> visitContinue(node)
+    is Return -> visitReturn(node)
     is NoneLiteral -> visitNoneLiteral(node)
     is NativeFunctionDescriptor -> visitNativeFunctionDescriptor(node)
     is IndexedBy -> visitIndexedBy(node)

ast/src/main/kotlin/gay/pizza/pork/ast/gen/Return.kt

@@ -0,0 +1,28 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast.gen
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("return")
+class Return(val value: Expression) : Expression() {
+  override val type: NodeType = NodeType.Return
+
+  override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
+    visitor.visitNodes(value)
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitReturn(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is Return) return false
+    return other.value == value
+  }
+
+  override fun hashCode(): Int {
+    var result = value.hashCode()
+    result = 31 * result + type.hashCode()
+    return result
+  }
+}