language: var, reassign, comparison operators

ast/src/main/ast/pork.yml

@@ -41,6 +41,20 @@ types:
       type: Symbol
     - name: value
       type: Expression
+  VarAssignment:
+    parent: Expression
+    values:
+    - name: symbol
+      type: Symbol
+    - name: value
+      type: Expression
+  SetAssignment:
+    parent: Expression
+    values:
+    - name: symbol
+      type: Symbol
+    - name: value
+      type: Expression
   InfixOperator:
     values:
     - name: token
@@ -70,6 +84,18 @@ types:
     - name: Remainder
       values:
         token: "rem"
+    - name: Lesser
+      values:
+        token: "<"
+    - name: Greater
+      values:
+        token: ">"
+    - name: GreaterEqual
+      values:
+        token: ">="
+    - name: LesserEqual
+      values:
+        token: "<="
   InfixOperation:
     parent: Expression
     values:

ast/src/main/graph/types.dot

@@ -8,6 +8,8 @@ digraph A {
   type_Block [shape=box,label="Block"]
   type_CompilationUnit [shape=box,label="CompilationUnit"]
   type_LetAssignment [shape=box,label="LetAssignment"]
+  type_VarAssignment [shape=box,label="VarAssignment"]
+  type_SetAssignment [shape=box,label="SetAssignment"]
   type_InfixOperator [shape=box,label="InfixOperator"]
   type_InfixOperation [shape=box,label="InfixOperation"]
   type_BooleanLiteral [shape=box,label="BooleanLiteral"]
@@ -35,6 +37,8 @@ digraph A {
   type_Node -> type_CompilationUnit
   type_Node -> type_Native
   type_Expression -> type_LetAssignment
+  type_Expression -> type_VarAssignment
+  type_Expression -> type_SetAssignment
   type_Expression -> type_InfixOperation
   type_Expression -> type_BooleanLiteral
   type_Expression -> type_FunctionCall
@@ -58,6 +62,10 @@ digraph A {
   type_CompilationUnit -> type_Definition [style=dotted]
   type_LetAssignment -> type_Symbol [style=dotted]
   type_LetAssignment -> type_Expression [style=dotted]
+  type_VarAssignment -> type_Symbol [style=dotted]
+  type_VarAssignment -> type_Expression [style=dotted]
+  type_SetAssignment -> type_Symbol [style=dotted]
+  type_SetAssignment -> type_Expression [style=dotted]
   type_InfixOperation -> type_Expression [style=dotted]
   type_InfixOperation -> type_InfixOperator [style=dotted]
   type_FunctionCall -> type_Symbol [style=dotted]

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

@@ -14,5 +14,9 @@ enum class InfixOperator(val token: String) {
   Equals("=="),
   NotEquals("!="),
   EuclideanModulo("mod"),
-  Remainder("rem")
+  Remainder("rem"),
+  Lesser("<"),
+  Greater(">"),
+  GreaterEqual(">="),
+  LesserEqual("<=")
 }

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

@@ -53,6 +53,9 @@ class NodeCoalescer(val handler: (Node) -> Unit) : NodeVisitor<Unit> {
   override fun visitPrefixOperation(node: PrefixOperation): Unit =
     handle(node)
 
+  override fun visitSetAssignment(node: SetAssignment): Unit =
+    handle(node)
+
   override fun visitStringLiteral(node: StringLiteral): Unit =
     handle(node)
 
@@ -62,6 +65,9 @@ class NodeCoalescer(val handler: (Node) -> Unit) : NodeVisitor<Unit> {
   override fun visitSymbolReference(node: SymbolReference): Unit =
     handle(node)
 
+  override fun visitVarAssignment(node: VarAssignment): Unit =
+    handle(node)
+
   override fun visitWhile(node: While): Unit =
     handle(node)
 

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

@@ -23,8 +23,10 @@ enum class NodeType(val parent: NodeType? = null) {
   Native(Node),
   Parentheses(Expression),
   PrefixOperation(Expression),
+  SetAssignment(Expression),
   StringLiteral(Expression),
   Symbol(Node),
   SymbolReference(Expression),
+  VarAssignment(Expression),
   While(Expression)
 }

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

@@ -36,11 +36,15 @@ interface NodeVisitor<T> {
 
   fun visitPrefixOperation(node: PrefixOperation): T
 
+  fun visitSetAssignment(node: SetAssignment): T
+
   fun visitStringLiteral(node: StringLiteral): T
 
   fun visitSymbol(node: Symbol): T
 
   fun visitSymbolReference(node: SymbolReference): T
 
+  fun visitVarAssignment(node: VarAssignment): T
+
   fun visitWhile(node: While): T
 }

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

@@ -7,6 +7,8 @@ fun <T> NodeVisitor<T>.visit(node: Node): T =
     is Block -> visitBlock(node)
     is CompilationUnit -> visitCompilationUnit(node)
     is LetAssignment -> visitLetAssignment(node)
+    is VarAssignment -> visitVarAssignment(node)
+    is SetAssignment -> visitSetAssignment(node)
     is InfixOperation -> visitInfixOperation(node)
     is BooleanLiteral -> visitBooleanLiteral(node)
     is FunctionCall -> visitFunctionCall(node)

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

@@ -0,0 +1,29 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("setAssignment")
+class SetAssignment(val symbol: Symbol, val value: Expression) : Expression() {
+  override val type: NodeType = NodeType.SetAssignment
+
+  override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
+    visitor.visitNodes(symbol, value)
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitSetAssignment(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is SetAssignment) return false
+    return other.symbol == symbol && other.value == value
+  }
+
+  override fun hashCode(): Int {
+    var result = symbol.hashCode()
+    result = 31 * result + value.hashCode()
+    result = 31 * result + type.hashCode()
+    return result
+  }
+}

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

@@ -0,0 +1,29 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("varAssignment")
+class VarAssignment(val symbol: Symbol, val value: Expression) : Expression() {
+  override val type: NodeType = NodeType.VarAssignment
+
+  override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
+    visitor.visitNodes(symbol, value)
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitVarAssignment(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is VarAssignment) return false
+    return other.symbol == symbol && other.value == value
+  }
+
+  override fun hashCode(): Int {
+    var result = symbol.hashCode()
+    result = 31 * result + value.hashCode()
+    result = 31 * result + type.hashCode()
+    return result
+  }
+}

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationVisitor.kt

@@ -26,13 +26,19 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
 
   override fun visitLetAssignment(node: LetAssignment): Any {
     val value = node.value.visit(this)
-    currentScope.define(node.symbol.id, value)
+    currentScope.define(node.symbol.id, value, ValueStoreType.Let)
     return value
   }
 
   override fun visitSymbolReference(node: SymbolReference): Any =
     currentScope.value(node.symbol.id)
 
+  override fun visitVarAssignment(node: VarAssignment): Any {
+    val value = node.value.visit(this)
+    currentScope.define(node.symbol.id, value, type = ValueStoreType.Var)
+    return value
+  }
+
   override fun visitWhile(node: While): Any {
     val blockFunction = node.block.visit(this) as BlockFunction
     var result: Any? = null
@@ -68,6 +74,12 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
     }
   }
 
+  override fun visitSetAssignment(node: SetAssignment): Any {
+    val value = node.value.visit(this)
+    currentScope.set(node.symbol.id, value)
+    return value
+  }
+
   override fun visitIf(node: If): Any {
     val condition = node.condition.visit(this)
     return if (condition == true) {
@@ -108,7 +120,11 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
         multiply = { a, b -> a * b },
         divide = { a, b -> a / b },
         euclideanModulo = { _, _ -> throw RuntimeException("Can't perform integer modulo between floating point types") },
-        remainder = { _, _ -> throw RuntimeException("Can't perform integer remainder between floating point types") }
+        remainder = { _, _ -> throw RuntimeException("Can't perform integer remainder between floating point types") },
+        lesser = { a, b -> a < b },
+        greater = { a, b -> a > b },
+        lesserEqual = { a, b -> a <= b },
+        greaterEqual = { a, b -> a >= b }
       )
     }
 
@@ -123,7 +139,11 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
         multiply = { a, b -> a * b },
         divide = { a, b -> a / b },
         euclideanModulo = { _, _ -> throw RuntimeException("Can't perform integer modulo between floating point types") },
-        remainder = { _, _ -> throw RuntimeException("Can't perform integer remainder between floating point types") }
+        remainder = { _, _ -> throw RuntimeException("Can't perform integer remainder between floating point types") },
+        lesser = { a, b -> a < b },
+        greater = { a, b -> a > b },
+        lesserEqual = { a, b -> a <= b },
+        greaterEqual = { a, b -> a >= b }
       )
     }
 
@@ -138,7 +158,11 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
         multiply = { a, b -> a * b },
         divide = { a, b -> a / b },
         euclideanModulo = { x, d -> (x % d).let { q -> if (q < 0) q + abs(d) else q } },
-        remainder = { x, d -> x % d }
+        remainder = { x, d -> x % d },
+        lesser = { a, b -> a < b },
+        greater = { a, b -> a > b },
+        lesserEqual = { a, b -> a <= b },
+        greaterEqual = { a, b -> a >= b }
       )
     }
 
@@ -153,7 +177,11 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
         multiply = { a, b -> a * b },
         divide = { a, b -> a / b },
         euclideanModulo = { x, d -> (x % d).let { q -> if (q < 0) q + abs(d) else q } },
-        remainder = { x, d -> x % d }
+        remainder = { x, d -> x % d },
+        lesser = { a, b -> a < b },
+        greater = { a, b -> a > b },
+        lesserEqual = { a, b -> a <= b },
+        greaterEqual = { a, b -> a >= b }
       )
     }
 
@@ -170,8 +198,12 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
     multiply: (T, T) -> T,
     divide: (T, T) -> T,
     euclideanModulo: (T, T) -> T,
-    remainder: (T, T) -> T
-  ): T {
+    remainder: (T, T) -> T,
+    lesser: (T, T) -> Boolean,
+    greater: (T, T) -> Boolean,
+    lesserEqual: (T, T) -> Boolean,
+    greaterEqual: (T, T) -> Boolean
+  ): Any {
     return when (op) {
       InfixOperator.Plus -> add(convert(left), convert(right))
       InfixOperator.Minus -> subtract(convert(left), convert(right))
@@ -179,6 +211,10 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
       InfixOperator.Divide -> divide(convert(left), convert(right))
       InfixOperator.EuclideanModulo -> euclideanModulo(convert(left), convert(right))
       InfixOperator.Remainder -> remainder(convert(left), convert(right))
+      InfixOperator.Lesser -> lesser(convert(left), convert(right))
+      InfixOperator.Greater -> greater(convert(left), convert(right))
+      InfixOperator.LesserEqual -> lesserEqual(convert(left), convert(right))
+      InfixOperator.GreaterEqual -> greaterEqual(convert(left), convert(right))
       else -> throw RuntimeException("Unable to handle operation $op")
     }
   }

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Scope.kt

@@ -6,43 +6,55 @@ class Scope(
   val name: String? = null
 ) {
   private val inherited = inherits.toMutableList()
-  private val variables = mutableMapOf<String, Any>()
+  private val variables = mutableMapOf<String, ValueStore>()
 
-  fun define(name: String, value: Any) {
-    val previous = variables.put(name, value)
+  fun define(name: String, value: Any, type: ValueStoreType = ValueStoreType.Let) {
+    val previous = variables.put(name, ValueStore(value, type))
     if (previous != null) {
       variables[name] = previous
       throw RuntimeException("Variable '${name}' is already defined")
     }
   }
 
-  fun value(name: String): Any {
-    val value = valueOrNotFound(name)
-    if (value === NotFound) {
+  fun set(name: String, value: Any) {
+    val holder = valueHolderOrNotFound(name)
+    if (holder.type == ValueStoreType.Let) {
+      throw RuntimeException("Variable '${name}' is already defined")
+    }
+
+    if (holder === NotFound.Holder) {
       throw RuntimeException("Variable '${name}' not defined")
     }
-    return value
+    holder.value = value
   }
 
-  private fun valueOrNotFound(name: String): Any {
-    val value = variables[name]
-    if (value == null) {
+  fun value(name: String): Any {
+    val holder = valueHolderOrNotFound(name)
+    if (holder === NotFound.Holder) {
+      throw RuntimeException("Variable '${name}' not defined")
+    }
+    return holder.value
+  }
+
+  private fun valueHolderOrNotFound(name: String): ValueStore {
+    val holder = variables[name]
+    if (holder == null) {
       if (parent != null) {
-        val parentMaybeFound = parent.valueOrNotFound(name)
-        if (parentMaybeFound !== NotFound) {
+        val parentMaybeFound = parent.valueHolderOrNotFound(name)
+        if (parentMaybeFound !== NotFound.Holder) {
           return parentMaybeFound
         }
       }
 
       for (inherit in inherited) {
-        val inheritMaybeFound = inherit.valueOrNotFound(name)
-        if (inheritMaybeFound !== NotFound) {
+        val inheritMaybeFound = inherit.valueHolderOrNotFound(name)
+        if (inheritMaybeFound !== NotFound.Holder) {
           return inheritMaybeFound
         }
       }
-      return NotFound
+      return NotFound.Holder
     }
-    return value
+    return holder
   }
 
   fun fork(name: String? = null): Scope =
@@ -80,5 +92,7 @@ class Scope(
     }
   }
 
-  private object NotFound
+  private object NotFound {
+    val Holder = ValueStore(NotFound, ValueStoreType.Let)
+  }
 }

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/ValueStore.kt

@@ -0,0 +1,5 @@
+package gay.pizza.pork.evaluator
+
+class ValueStore(var value: Any, val type: ValueStoreType) {
+  override fun toString(): String = "${type.name}: $value"
+}

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/ValueStoreType.kt

@@ -0,0 +1,6 @@
+package gay.pizza.pork.evaluator
+
+enum class ValueStoreType {
+  Let,
+  Var
+}

examples/count.pork

@@ -0,0 +1,7 @@
+export func main() {
+  var x = 1
+  while x <= 5 {
+    println(x)
+    x = x + 1
+  }
+}

parser/src/main/kotlin/gay/pizza/pork/parser/DiscardNodeAttribution.kt

@@ -5,5 +5,6 @@ import gay.pizza.pork.ast.Node
 object DiscardNodeAttribution : NodeAttribution {
   override fun enter() {}
   override fun push(token: Token) {}
+  override fun <T : Node> adopt(node: T) {}
   override fun <T : Node> exit(node: T): T = node
 }

parser/src/main/kotlin/gay/pizza/pork/parser/NodeAttribution.kt

@@ -5,5 +5,6 @@ import gay.pizza.pork.ast.Node
 interface NodeAttribution {
   fun enter()
   fun push(token: Token)
+  fun <T: Node> adopt(node: T)
   fun <T: Node> exit(node: T): T
 }

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

@@ -45,6 +45,14 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
     LetAssignment(symbol, value)
   }
 
+  private fun readVarAssignment(): VarAssignment = within {
+    expect(TokenType.Var)
+    val symbol = readSymbolRaw()
+    expect(TokenType.Equals)
+    val value = readExpression()
+    VarAssignment(symbol, value)
+  }
+
   private fun readSymbolRaw(): Symbol = within {
     expect(TokenType.Symbol) { Symbol(it.text) }
   }
@@ -123,6 +131,10 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
         readLetAssignment()
       }
 
+      TokenType.Var -> {
+        readVarAssignment()
+      }
+
       TokenType.Symbol -> {
         readSymbolCases()
       }
@@ -161,6 +173,15 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
       }
     }
 
+    if (expression is SymbolReference && peek(TokenType.Equals)) {
+      return within {
+        attribution.adopt(expression)
+        expect(TokenType.Equals)
+        val value = readExpression()
+        SetAssignment(expression.symbol, value)
+      }
+    }
+
     return if (peek(
         TokenType.Plus,
         TokenType.Minus,
@@ -169,7 +190,11 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
         TokenType.Equality,
         TokenType.Inequality,
         TokenType.Mod,
-        TokenType.Rem
+        TokenType.Rem,
+        TokenType.Lesser,
+        TokenType.Greater,
+        TokenType.LesserEqual,
+        TokenType.GreaterEqual
       )
     ) {
       within {
@@ -268,6 +293,10 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
       TokenType.Inequality -> InfixOperator.NotEquals
       TokenType.Mod -> InfixOperator.EuclideanModulo
       TokenType.Rem -> InfixOperator.Remainder
+      TokenType.Lesser -> InfixOperator.Lesser
+      TokenType.Greater -> InfixOperator.Greater
+      TokenType.LesserEqual -> InfixOperator.LesserEqual
+      TokenType.GreaterEqual -> InfixOperator.GreaterEqual
       else -> throw RuntimeException("Unknown Infix Operator")
     }
 

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

@@ -95,6 +95,13 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
     visit(node.symbol)
   }
 
+  override fun visitVarAssignment(node: VarAssignment) {
+    append("var ")
+    visit(node.symbol)
+    append(" = ")
+    visit(node.value)
+  }
+
   override fun visitWhile(node: While) {
     append("while ")
     visit(node.condition)
@@ -113,6 +120,12 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
     visit(node.expression)
   }
 
+  override fun visitSetAssignment(node: SetAssignment) {
+    visit(node.symbol)
+    append(" = ")
+    visit(node.value)
+  }
+
   override fun visitIf(node: If) {
     append("if ")
     visit(node.condition)

parser/src/main/kotlin/gay/pizza/pork/parser/TokenNodeAttribution.kt

@@ -22,6 +22,15 @@ class TokenNodeAttribution : NodeAttribution {
     store.add(token)
   }
 
+  override fun <T : Node> adopt(node: T) {
+    val tokens = nodes.remove(node)
+    if (tokens != null) {
+      for (token in tokens) {
+        push(token)
+      }
+    }
+  }
+
   override fun <T: Node> exit(node: T): T {
     val store = stack.removeLast()
     nodes[node] = store

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

@@ -19,6 +19,10 @@ enum class TokenType(vararg properties: TokenTypeProperty) {
   Minus(SingleChar('-'), OperatorFamily),
   Multiply(SingleChar('*'), OperatorFamily),
   Divide(SingleChar('/'), OperatorFamily),
+  LesserEqual(OperatorFamily),
+  GreaterEqual(OperatorFamily),
+  Lesser(SingleChar('<'), OperatorFamily, Promotion('=', LesserEqual)),
+  Greater(SingleChar('>'), OperatorFamily, Promotion('=', GreaterEqual)),
   LeftCurly(SingleChar('{')),
   RightCurly(SingleChar('}')),
   LeftBracket(SingleChar('[')),
@@ -42,6 +46,7 @@ enum class TokenType(vararg properties: TokenTypeProperty) {
   Func(Keyword("func"), KeywordFamily),
   Native(Keyword("native"), KeywordFamily),
   Let(Keyword("let"), KeywordFamily),
+  Var(Keyword("var"), KeywordFamily),
   Whitespace(CharConsumer { it == ' ' || it == '\r' || it == '\n' || it == '\t' }),
   BlockComment(CommentFamily),
   LineComment(CommentFamily),