String literal support.

examples/syntax.pork

@@ -49,4 +49,5 @@ results = [
   notEqual(5, 6)
 ]
 
+println("results:")
 println(results)

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

@@ -12,6 +12,7 @@ class NodeCoalescer(val handler: (Node) -> Unit) : NodeVisitor<Unit> {
   override fun visitIntLiteral(node: IntLiteral) = handler(node)
   override fun visitBooleanLiteral(node: BooleanLiteral) = handler(node)
   override fun visitListLiteral(node: ListLiteral) = handler(node)
+  override fun visitStringLiteral(node: StringLiteral) = handler(node)
   override fun visitParentheses(node: Parentheses) = handler(node)
   override fun visitPrefixOperation(node: PrefixOperation) = handler(node)
   override fun visitInfixOperation(node: InfixOperation) = handler(node)

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

@@ -1,20 +1,19 @@
 package gay.pizza.pork.ast
 
-import gay.pizza.pork.ast.NodeTypeTrait.*
-
-enum class NodeType(val parent: NodeType? = null, vararg traits: NodeTypeTrait) {
+enum class NodeType(val parent: NodeType? = null) {
   Node,
   Symbol(Node),
-  Expression(Node, Intermediate),
+  Expression(Node),
   Program(Node),
-  IntLiteral(Expression, Literal),
-  BooleanLiteral(Expression, Literal),
-  ListLiteral(Expression, Literal),
+  IntLiteral(Expression),
+  BooleanLiteral(Expression),
+  ListLiteral(Expression),
+  StringLiteral(Expression),
   Parentheses(Expression),
   Define(Expression),
   Lambda(Expression),
-  PrefixOperation(Expression, Operation),
-  InfixOperation(Expression, Operation),
+  PrefixOperation(Expression),
+  InfixOperation(Expression),
   SymbolReference(Expression),
   FunctionCall(Expression),
   If(Expression);

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

@@ -13,6 +13,7 @@ interface NodeVisitor<T> {
   fun visitIntLiteral(node: IntLiteral): T
   fun visitBooleanLiteral(node: BooleanLiteral): T
   fun visitListLiteral(node: ListLiteral): T
+  fun visitStringLiteral(node: StringLiteral): T
 
   fun visitParentheses(node: Parentheses): T
   fun visitPrefixOperation(node: PrefixOperation): T
@@ -24,6 +25,7 @@ interface NodeVisitor<T> {
     is IntLiteral -> visitIntLiteral(node)
     is BooleanLiteral -> visitBooleanLiteral(node)
     is ListLiteral -> visitListLiteral(node)
+    is StringLiteral -> visitStringLiteral(node)
     is Parentheses -> visitParentheses(node)
     is InfixOperation -> visitInfixOperation(node)
     is PrefixOperation -> visitPrefixOperation(node)
@@ -32,14 +34,12 @@ interface NodeVisitor<T> {
     is FunctionCall -> visitFunctionCall(node)
     is SymbolReference -> visitReference(node)
     is If -> visitIf(node)
-    else -> throw RuntimeException("Unknown Expression")
   }
 
   fun visit(node: Node): T = when (node) {
     is Expression -> visitExpression(node)
     is Symbol -> visitSymbol(node)
     is Program -> visitProgram(node)
-    else -> throw RuntimeException("Unknown Node")
   }
 
   fun visitNodes(vararg nodes: Node?): List<T> =

src/main/kotlin/gay/pizza/pork/ast/Printer.kt

@@ -1,6 +1,7 @@
 package gay.pizza.pork.ast
 
 import gay.pizza.pork.ast.nodes.*
+import gay.pizza.pork.util.StringEscape
 
 class Printer(private val buffer: StringBuilder) : NodeVisitor<Unit> {
   private var indent = 0
@@ -109,6 +110,12 @@ class Printer(private val buffer: StringBuilder) : NodeVisitor<Unit> {
     append("]")
   }
 
+  override fun visitStringLiteral(node: StringLiteral) {
+    append("\"")
+    append(StringEscape.escape(node.text))
+    append("\"")
+  }
+
   override fun visitParentheses(node: Parentheses) {
     append("(")
     visit(node.expression)

src/main/kotlin/gay/pizza/pork/ast/nodes/StringLiteral.kt

@@ -0,0 +1,18 @@
+package gay.pizza.pork.ast.nodes
+
+import gay.pizza.pork.ast.NodeType
+
+class StringLiteral(val text: String) : Expression() {
+  override val type: NodeType = NodeType.StringLiteral
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is StringLiteral) return false
+    return other.text == text
+  }
+
+  override fun hashCode(): Int {
+    var result = text.hashCode()
+    result = 31 * result + type.hashCode()
+    return result
+  }
+}

src/main/kotlin/gay/pizza/pork/compiler/KotlinCompiler.kt

@@ -2,6 +2,7 @@ package gay.pizza.pork.compiler
 
 import gay.pizza.pork.ast.*
 import gay.pizza.pork.ast.nodes.*
+import gay.pizza.pork.util.StringEscape
 
 class KotlinCompiler : NodeVisitor<String> {
   override fun visitDefine(node: Define): String =
@@ -55,6 +56,9 @@ class KotlinCompiler : NodeVisitor<String> {
     append(")")
   }
 
+  override fun visitStringLiteral(node: StringLiteral): String =
+    "\"" + StringEscape.escape(node.text) + "\""
+
   override fun visitParentheses(node: Parentheses): String =
     "(${visit(node.expression)})"
 

src/main/kotlin/gay/pizza/pork/eval/Arguments.kt

@@ -1,7 +1,3 @@
 package gay.pizza.pork.eval
 
-class Arguments(val values: List<Any>) {
-  companion object {
-    val Zero = Arguments(emptyList())
-  }
-}
+class Arguments(val values: List<Any>)

src/main/kotlin/gay/pizza/pork/eval/Evaluator.kt

@@ -58,6 +58,7 @@ class Evaluator(root: Scope) : NodeVisitor<Any> {
   override fun visitIntLiteral(node: IntLiteral): Any = node.value
   override fun visitBooleanLiteral(node: BooleanLiteral): Any = node.value
   override fun visitListLiteral(node: ListLiteral): Any = node.items.map { visit(it) }
+  override fun visitStringLiteral(node: StringLiteral): Any = node.text
 
   override fun visitParentheses(node: Parentheses): Any = visit(node.expression)
 

src/main/kotlin/gay/pizza/pork/parse/AnsiHighlightScheme.kt

@@ -3,6 +3,7 @@ package gay.pizza.pork.parse
 open class AnsiHighlightScheme : HighlightScheme {
   override fun highlight(token: Token): Highlight {
     val attributes = when (token.type.family) {
+      TokenFamily.StringLiteralFamily -> string()
       TokenFamily.OperatorFamily -> operator()
       TokenFamily.KeywordFamily -> keyword()
       TokenFamily.SymbolFamily -> symbol()
@@ -15,8 +16,9 @@ open class AnsiHighlightScheme : HighlightScheme {
     } else Highlight(token)
   }
 
-  open fun operator(): AnsiAttributes = AnsiAttributes("32m")
+  open fun string(): AnsiAttributes = AnsiAttributes("32m")
   open fun symbol(): AnsiAttributes = AnsiAttributes("33m")
+  open fun operator(): AnsiAttributes = AnsiAttributes("34m")
   open fun keyword(): AnsiAttributes = AnsiAttributes("35m")
   open fun comment(): AnsiAttributes = AnsiAttributes("37m")
 

src/main/kotlin/gay/pizza/pork/parse/Parser.kt

@@ -1,6 +1,7 @@
 package gay.pizza.pork.parse
 
 import gay.pizza.pork.ast.nodes.*
+import gay.pizza.pork.util.StringEscape
 
 class Parser(source: PeekableSource<Token>) {
   private val unsanitizedSource = source
@@ -65,6 +66,11 @@ class Parser(source: PeekableSource<Token>) {
   fun readExpression(): Expression {
     val token = peek()
     val expression = when (token.type) {
+      TokenType.StringLiteral -> {
+        expect(TokenType.StringLiteral)
+        return StringLiteral(StringEscape.unescape(StringEscape.unquote(token.text)))
+      }
+
       TokenType.IntLiteral -> {
         readIntLiteral()
       }

src/main/kotlin/gay/pizza/pork/parse/TokenFamily.kt

@@ -5,6 +5,7 @@ enum class TokenFamily : TokenTypeProperty {
   KeywordFamily,
   SymbolFamily,
   NumericLiteralFamily,
+  StringLiteralFamily,
   CommentFamily,
   OtherFamily
 }

src/main/kotlin/gay/pizza/pork/parse/TokenType.kt

@@ -6,6 +6,7 @@ import gay.pizza.pork.parse.TokenFamily.*
 enum class TokenType(vararg properties: TokenTypeProperty) {
   Symbol(SymbolFamily),
   IntLiteral(NumericLiteralFamily),
+  StringLiteral(StringLiteralFamily),
   Equality(OperatorFamily),
   Inequality(OperatorFamily),
   Equals(SingleChar('='), Promotion('=', Equality)),

src/main/kotlin/gay/pizza/pork/parse/Tokenizer.kt

@@ -89,6 +89,23 @@ class Tokenizer(val source: CharSource) {
     return Token(TokenType.LineComment, tokenStart, comment)
   }
 
+  private fun readStringLiteral(firstChar: Char): Token {
+    val string = buildString {
+      append(firstChar)
+      while (true) {
+        val char = source.peek()
+        if (char == CharSource.NullChar) {
+          throw RuntimeException("Unterminated string.")
+        }
+        append(source.next())
+        if (char == '"') {
+          break
+        }
+      }
+    }
+    return Token(TokenType.StringLiteral, tokenStart, string)
+  }
+
   fun next(): Token {
     while (source.peek() != CharSource.NullChar) {
       tokenStart = source.currentIndex
@@ -132,6 +149,11 @@ class Tokenizer(val source: CharSource) {
       if (isSymbol(char)) {
         return readSymbolOrKeyword(char)
       }
+
+      if (char == '"') {
+        return readStringLiteral(char)
+      }
+
       throw RuntimeException("Failed to parse: (${char}) next ${source.peek()}")
     }
     return Token.endOfFile(source.currentIndex)

src/main/kotlin/gay/pizza/pork/util/StringEscape.kt

@@ -0,0 +1,8 @@
+package gay.pizza.pork.util
+
+object StringEscape {
+  fun escape(input: String): String = input.replace("\n", "\\n")
+  fun unescape(input: String): String = input.replace("\\n", "\n")
+
+  fun unquote(input: String): String = input.substring(1, input.length - 1)
+}