parsetreetypes.js

// \texttt{parsetreetypes.js START} \begin{lstlisting}

// Types used to describe the shape of the parse tree
// that is generated by the parse function in Source 4.

// Program
type Program = Pair<"sequence", Pair<List<Statement>, null>>;

// Statement
type Statement =
  | ConstantDeclaration
  | VariableDeclaration
  | FunctionDeclaration
  | ReturnStatement
  | ConditionalStatement
  | WhileLoop
  | ForLoop
  | BreakStatement
  | ContinueStatement
  | Block
  | Expression;

type ConstantDeclaration = Pair<"constant_declaration",
  Pair<Name, Pair<Expression, null>>>;
type FunctionDeclaration = Pair<"function_declaration",
  Pair<Name, Pair<Parameters, Pair<Block, null>>>>;
type ReturnStatement = Pair<"return_statement", Pair<Expression, null>>;
type WhileLoop = Pair<"while_loop", Pair<Expression, Pair<Block, null>>>;
type ForLoop = Pair<"for_loop", Pair<Expression | VariableDeclaration,
  Pair<Expression, Pair<Expression, Pair<Block, null>>>>>;
type BreakStatement = Pair<"break_statement", null>;
type ContinueStatement = Pair<"continue_statement", null>;

// Parameters
type Parameters = List<Name>;

// If-Statement
type ConditionalStatement = Pair<"conditional_statement", Pair<Expression,
  Pair<Block, Pair<Block | ConditionalStatement, null>>>>;

// Block
type Block = Pair<"block", Pair<Program, null>>;

// Let
type VariableDeclaration = Pair<"variable_declaration",
  Pair<Name, Pair<Expression, null>>>;

// Assignment
type Assignment = Pair<"assignment", Pair<Name, Pair<Expression, null>>>;
type ObjectAssignment = Pair<"object_assignment",
  Pair<ObjectAccess, Pair<Expression, null>>>;

// Expression
type Expression =
  | Literal
  | Name
  | LogicalComposition
  | BinaryOperatorCombination
  | UnaryOperatorCombination
  | Application
  | LambdaExpression
  | ConditionalExpression
  | Assignment
  | ObjectAssignment
  | ObjectAccess
  | ArrayExpression;

type Literal = Pair<"literal", Pair<number | string | boolean | null, null>>;
type Name = Pair<"name", Pair<string, null>>;
  type LogicalComposition = Pair<"logical_composition", Pair<LogicalOperator,
Pair<Expression, Pair<Expression, null>>>>;
type BinaryOperatorCombination = Pair<"binary_operator_combination",
  Pair<BinaryOperator, Pair<Expression, Pair<Expression, null>>>>;
type UnaryOperatorCombination = Pair<"unary_operator_combination",
  Pair<UnaryOperator, Pair<Expression, null>>>;
type Application = Pair<"application", Pair<Expression,
  Pair<List<Expression>, null>>>;
type LambdaExpression = Pair<"lambda_expression", Pair<Parameters,
  Pair<Statement, null>>>;
type ConditionalExpression = Pair<"conditional_expression", Pair<Expression,
  Pair<Expression, Pair<Expression, null>>>>;
type ObjectAccess = Pair<"object_access", Pair<Expression, Pair<Expression, null>>>;
type ArrayExpression = Pair<"array_expression", Pair<List<Expression>, null>>;

// Operators
type LogicalOperator = "&&" | "||";
type BinaryOperator = "+" | "-" | "*" | "/" | "%" | "==="
  | "!==" | "<" | ">" | "<=" | ">=";
type UnaryOperator = "!" | "-unary";

// \end{lstlisting} // \texttt{parsetreetypes.js END}