756 lines
23 KiB
Rust
756 lines
23 KiB
Rust
use tokenizer::{Token, Kw, OpTok};
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use tokenizer::Token::*;
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use std::fmt;
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use std::collections::VecDeque;
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use std::rc::Rc;
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use std::convert::From;
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// Grammar
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// program := (statement delimiter ?)*
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// delimiter := Newline | Semicolon
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// statement := declaration | expression
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// declaration := FN prototype LCurlyBrace (statement)* RCurlyBrace
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// prototype := identifier LParen identlist RParen
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// identlist := Ident (Comma Ident)* | ε
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// exprlist := Expression (Comma Expression)* | ε
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// itemlist := Ident COLON Expression (Comma Ident COLON Expression)* | ε
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//
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// expression := postop_expression (op postop_expression)*
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// postop_expression := primary_expression postop
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// primary_expression := number_expr | String | identifier_expr | paren_expr | conditional_expr | while_expr | lambda_expr | list_expr | struct_expr
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// number_expr := (PLUS | MINUS ) number_expr | Number
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// identifier_expr := call_expression | Variable
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// list_expr := LSquareBracket exprlist RSquareBracket
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// struct_expr := LCurlyBrace itemlist RCurlyBrace
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// call_expression := Identifier LParen exprlist RParen
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// while_expr := WHILE primary_expression LCurlyBrace (expression delimiter)* RCurlyBrace
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// paren_expr := LParen expression RParen
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// conditional_expr := IF expression LCurlyBrace (expression delimiter)* RCurlyBrace (LCurlyBrace (expresion delimiter)* RCurlyBrace)?
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// lambda_expr := FN LParen identlist RParen LCurlyBrace (expression delimiter)* RCurlyBrace
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// lambda_call := | LParen exprlist RParen
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// postop := ε | LParen exprlist RParen | LBracket expression RBracket
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// op := '+', '-', etc.
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//
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pub type AST = Vec<Statement>;
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#[derive(Debug, Clone)]
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pub enum Statement {
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ExprNode(Expression),
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FuncDefNode(Function),
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}
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impl fmt::Display for Statement {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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use self::Statement::*;
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match *self {
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ExprNode(ref expr) => write!(f, "{}", expr),
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FuncDefNode(_) => write!(f, "UNIMPLEMENTED"),
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}
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}
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}
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#[derive(Debug, Clone)]
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pub struct Function {
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pub prototype: Prototype,
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pub body: Vec<Statement>,
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}
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#[derive(Debug, Clone, PartialEq)]
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pub struct Prototype {
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pub name: Rc<String>,
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pub parameters: Vec<Rc<String>>,
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}
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#[derive(Debug, Clone)]
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pub enum Expression {
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Null,
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StringLiteral(Rc<String>),
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Number(f64),
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Variable(Rc<String>),
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BinExp(BinOp, Box<Expression>, Box<Expression>),
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Call(Callable, Vec<Expression>),
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Conditional(Box<Expression>, Box<Expression>, Option<Box<Expression>>),
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Lambda(Function),
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Block(VecDeque<Expression>),
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While(Box<Expression>, Vec<Expression>),
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Index(Box<Expression>, Box<Expression>),
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ListLiteral(VecDeque<Expression>),
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StructLiteral(VecDeque<(Rc<String>, Expression)>),
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}
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#[derive(Clone, Debug)]
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pub enum Callable {
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NamedFunction(Rc<String>),
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Lambda(Function),
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}
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//TODO this ought to be ReducedExpression
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impl fmt::Display for Expression {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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use self::Expression::*;
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match *self {
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Null => write!(f, "null"),
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StringLiteral(ref s) => write!(f, "\"{}\"", s),
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Number(n) => write!(f, "{}", n),
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Lambda(Function { prototype: Prototype { ref name, ref parameters, .. }, .. }) => {
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write!(f, "«function: {}, {} arg(s)»", name, parameters.len())
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}
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ListLiteral(ref items) => {
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write!(f, "[ ")?;
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let mut iter = items.iter().peekable();
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while let Some(item) = iter.next() {
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write!(f, "{}", item)?;
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if let Some(_) = iter.peek() {
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write!(f, ", ")?;
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}
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}
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write!(f, " ]")
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}
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StructLiteral(ref items) => {
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write!(f, "{} ", "{")?;
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let mut iter = items.iter().peekable();
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while let Some(pair) = iter.next() {
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write!(f, "{}: {}", pair.0, pair.1)?;
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if let Some(_) = iter.peek() {
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write!(f, ", ")?;
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}
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}
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write!(f, "{} ", "}")
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}
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_ => write!(f, "UNIMPLEMENTED"),
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}
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}
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}
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#[derive(Debug, Clone)]
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pub enum BinOp {
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Add,
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AddAssign,
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Sub,
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SubAssign,
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Mul,
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MulAssign,
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Div,
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DivAssign,
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Mod,
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Less,
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LessEq,
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Greater,
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GreaterEq,
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Equal,
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Assign,
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Custom(String),
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}
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impl From<OpTok> for BinOp {
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fn from(token: OpTok) -> BinOp {
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use self::BinOp::*;
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match &token.0[..] {
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"+" => Add,
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"+=" => AddAssign,
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"-" => Sub,
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"-=" => SubAssign,
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"*" => Mul,
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"*=" => MulAssign,
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"/" => Div,
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"/=" => DivAssign,
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"%" => Mod,
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"<" => Less,
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"<=" => LessEq,
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">" => Greater,
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">=" => GreaterEq,
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"==" => Equal,
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"=" => Assign,
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op => Custom(op.to_string()),
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}
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}
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}
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type Precedence = u8;
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// TODO make this support incomplete parses
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pub type ParseResult<T> = Result<T, ParseError>;
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#[derive(Debug)]
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pub struct ParseError {
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pub msg: String,
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pub remaining_tokens: Vec<Token>,
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}
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impl ParseError {
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fn result_from_str<T>(msg: &str) -> ParseResult<T> {
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Err(ParseError {
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msg: msg.to_string(),
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remaining_tokens: vec![],
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})
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}
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}
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struct Parser {
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tokens: Vec<Token>,
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}
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impl Parser {
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fn initialize(tokens: &[Token]) -> Parser {
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let mut tokens = tokens.to_vec();
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tokens.reverse();
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Parser { tokens: tokens }
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}
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fn peek(&self) -> Option<Token> {
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self.tokens.last().map(|x| x.clone())
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}
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fn next(&mut self) -> Option<Token> {
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self.tokens.pop()
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}
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fn get_precedence(&self, op: &OpTok) -> Precedence {
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match &op.0[..] {
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"+" => 10,
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"-" => 10,
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"*" => 20,
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"/" => 20,
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"%" => 20,
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"==" => 40,
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"=" | "+=" | "-=" | "*=" | "/=" => 1,
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">" | ">=" | "<" | "<=" => 30,
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_ => 255,
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}
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}
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}
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macro_rules! expect {
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($self_:expr, $token:pat) => {
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match $self_.peek() {
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Some($token) => {$self_.next();},
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Some(x) => {
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let err = format!("Expected `{:?}` but got `{:?}`", stringify!($token), x);
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return ParseError::result_from_str(&err)
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},
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None => {
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let err = format!("Expected `{:?}` but got end of input", stringify!($token));
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return ParseError::result_from_str(&err) //TODO make this not require 2 stringifications
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}
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}
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}
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}
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macro_rules! expect_identifier {
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($self_:expr) => {
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match $self_.peek() {
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Some(Identifier(s)) => {$self_.next(); s},
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Some(x) => return ParseError::result_from_str(&format!("Expected identifier, but got {:?}", x)),
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None => return ParseError::result_from_str("Expected identifier, but got end of input"),
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}
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}
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}
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macro_rules! skip_whitespace {
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($_self: expr) => {
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loop {
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match $_self.peek() {
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Some(ref t) if is_delimiter(t) => {
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$_self.next();
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continue;
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}
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_ => break,
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}
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}
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}
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}
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macro_rules! delimiter_block {
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($_self: expr, $try_parse: ident, $($break_pattern: pat)|+) => {
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{
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let mut acc = Vec::new();
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loop {
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match $_self.peek() {
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None => break,
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Some(ref t) if is_delimiter(t) => { $_self.next(); continue; },
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$($break_pattern)|+ => break,
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_ => {
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let a = try!($_self.$try_parse());
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acc.push(a);
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}
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}
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}
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acc
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}
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}
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}
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fn is_delimiter(token: &Token) -> bool {
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match *token {
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Newline | Semicolon => true,
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_ => false,
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}
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}
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impl Parser {
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fn program(&mut self) -> ParseResult<AST> {
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let mut ast = Vec::new(); //TODO have this come from previously-parsed tree
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loop {
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let result: ParseResult<Statement> = match self.peek() {
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Some(ref t) if is_delimiter(t) => {
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self.next();
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continue;
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}
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Some(_) => self.statement(),
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None => break,
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};
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match result {
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Ok(node) => ast.push(node),
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Err(mut err) => {
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err.remaining_tokens = self.tokens.clone();
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err.remaining_tokens.reverse();
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return Err(err);
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}
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}
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}
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Ok(ast)
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}
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fn statement(&mut self) -> ParseResult<Statement> {
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let node: Statement = match self.peek() {
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Some(Keyword(Kw::Fn)) => self.declaration()?,
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Some(_) => Statement::ExprNode(self.expression()?),
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None => panic!("Unexpected end of tokens"),
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};
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Ok(node)
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}
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fn declaration(&mut self) -> ParseResult<Statement> {
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expect!(self, Keyword(Kw::Fn));
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let prototype = self.prototype()?;
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expect!(self, LCurlyBrace);
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let body = self.body()?;
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expect!(self, RCurlyBrace);
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Ok(Statement::FuncDefNode(Function {
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prototype: prototype,
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body: body,
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}))
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}
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fn prototype(&mut self) -> ParseResult<Prototype> {
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let name = expect_identifier!(self);
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expect!(self, LParen);
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let parameters = self.identlist()?;
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expect!(self, RParen);
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Ok(Prototype {
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name: name,
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parameters: parameters,
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})
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}
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fn identlist(&mut self) -> ParseResult<Vec<Rc<String>>> {
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let mut args = Vec::new();
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while let Some(Identifier(name)) = self.peek() {
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args.push(name.clone());
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self.next();
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match self.peek() {
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Some(Comma) => {self.next();},
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_ => break,
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}
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}
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Ok(args)
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}
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fn exprlist(&mut self) -> ParseResult<Vec<Expression>> {
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let mut exprs = Vec::new();
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loop {
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if let Some(RParen) = self.peek() {
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break;
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}
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let exp = self.expression()?;
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exprs.push(exp);
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match self.peek() {
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Some(Comma) => {self.next();},
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_ => break,
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}
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}
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Ok(exprs)
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}
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fn itemlist(&mut self) -> ParseResult<VecDeque<(Rc<String>, Expression)>> {
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let mut items = VecDeque::new();
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loop {
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if let Some(RCurlyBrace) = self.peek() {
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break;
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}
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let name = expect_identifier!(self);
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expect!(self, Colon);
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let expr = self.expression()?;
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items.push_back((name, expr));
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match self.peek() {
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Some(Comma) => {self.next();},
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_ => break,
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};
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}
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Ok(items)
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}
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fn body(&mut self) -> ParseResult<Vec<Statement>> {
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let statements = delimiter_block!(
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self,
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statement,
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Some(RCurlyBrace)
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);
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Ok(statements)
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}
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fn expression(&mut self) -> ParseResult<Expression> {
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let lhs: Expression = self.postop_expression()?;
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self.precedence_expr(lhs, 0)
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}
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fn precedence_expr(&mut self,
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mut lhs: Expression,
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min_precedence: u8)
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-> ParseResult<Expression> {
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while let Some(Operator(op)) = self.peek() {
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let precedence = self.get_precedence(&op);
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if precedence < min_precedence {
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break;
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}
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self.next();
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let mut rhs = self.postop_expression()?;
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while let Some(Operator(ref op)) = self.peek() {
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if self.get_precedence(op) > precedence {
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let new_prec = self.get_precedence(op);
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rhs = self.precedence_expr(rhs, new_prec)?;
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} else {
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break;
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}
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}
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lhs = Expression::BinExp(op.into(), Box::new(lhs), Box::new(rhs));
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}
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Ok(lhs)
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}
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fn postop_expression(&mut self) -> ParseResult<Expression> {
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use self::Expression::*;
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let expr = self.primary_expression()?;
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let ret = match self.peek() {
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Some(LParen) => {
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let args = self.call_expression()?;
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match expr {
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Lambda(f) => Call(Callable::Lambda(f), args),
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e => {
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let err = format!("Expected lambda expression before a call, got {:?}", e);
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return ParseError::result_from_str(&err);
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},
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}
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},
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Some(LSquareBracket) => {
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expect!(self, LSquareBracket);
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let index_expr = self.expression()?;
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expect!(self, RSquareBracket);
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Index(Box::new(expr), Box::new(index_expr))
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},
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_ => {
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expr
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}
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};
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Ok(ret)
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}
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fn primary_expression(&mut self) -> ParseResult<Expression> {
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Ok(match self.peek() {
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Some(Keyword(Kw::Null)) => {
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self.next();
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Expression::Null
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}
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Some(NumLiteral(_)) => self.number_expression()?,
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Some(Operator(OpTok(ref a))) if **a == "+" || **a == "-" => self.number_expression()?,
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Some(StrLiteral(s)) => {
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self.next();
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Expression::StringLiteral(s)
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}
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Some(Keyword(Kw::If)) => self.conditional_expr()?,
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Some(Keyword(Kw::While)) => self.while_expr()?,
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Some(Identifier(_)) => self.identifier_expr()?,
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Some(Token::LParen) => self.paren_expr()?,
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Some(Keyword(Kw::Fn)) => self.lambda_expr()?,
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Some(Token::LSquareBracket) => self.list_expr()?,
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Some(Token::LCurlyBrace) => self.struct_expr()?,
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Some(e) => {
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return ParseError::result_from_str(&format!("Expected primary expression, got \
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{:?}",
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e));
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}
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None => return ParseError::result_from_str("Expected primary expression received EoI"),
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})
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}
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fn list_expr(&mut self) -> ParseResult<Expression> {
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expect!(self, LSquareBracket);
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let exprlist: Vec<Expression> = self.exprlist()?;
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expect!(self, RSquareBracket);
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Ok(Expression::ListLiteral(VecDeque::from(exprlist)))
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}
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fn struct_expr(&mut self) -> ParseResult<Expression> {
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expect!(self, LCurlyBrace);
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let struct_items = self.itemlist()?;
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expect!(self, RCurlyBrace);
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Ok(Expression::StructLiteral(struct_items))
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}
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fn number_expression(&mut self) -> ParseResult<Expression> {
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let mut multiplier = 1;
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loop {
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match self.peek() {
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Some(NumLiteral(n)) => {
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self.next();
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return Ok(Expression::Number(n * multiplier as f64));
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}
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Some(Operator(OpTok(ref a))) if **a == "+" => {
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self.next();
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}
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Some(Operator(OpTok(ref a))) if **a == "-" => {
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multiplier *= -1;
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self.next();
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}
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Some(e) => {
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return ParseError::result_from_str(
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&format!("Expected +, - or number, got {:?}", e));
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}
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None => {
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return ParseError::result_from_str(
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&format!("Expected +, - or number, got EoI"));
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}
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}
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}
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}
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fn lambda_expr(&mut self) -> ParseResult<Expression> {
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use self::Expression::*;
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expect!(self, Keyword(Kw::Fn));
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skip_whitespace!(self);
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expect!(self, LParen);
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let parameters = self.identlist()?;
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expect!(self, RParen);
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skip_whitespace!(self);
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expect!(self, LCurlyBrace);
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let body = self.body()?;
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expect!(self, RCurlyBrace);
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let prototype = Prototype {
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name: Rc::new("a lambda yo!".to_string()),
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parameters: parameters,
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};
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let function = Function {
|
|
prototype: prototype,
|
|
body: body,
|
|
};
|
|
|
|
Ok(Lambda(function))
|
|
}
|
|
|
|
fn while_expr(&mut self) -> ParseResult<Expression> {
|
|
use self::Expression::*;
|
|
expect!(self, Keyword(Kw::While));
|
|
let test = self.expression()?;
|
|
expect!(self, LCurlyBrace);
|
|
let body = delimiter_block!(
|
|
self,
|
|
expression,
|
|
Some(RCurlyBrace)
|
|
);
|
|
expect!(self, RCurlyBrace);
|
|
Ok(While(Box::new(test), body))
|
|
}
|
|
|
|
fn conditional_expr(&mut self) -> ParseResult<Expression> {
|
|
use self::Expression::*;
|
|
expect!(self, Keyword(Kw::If));
|
|
let test = self.expression()?;
|
|
skip_whitespace!(self);
|
|
expect!(self, LCurlyBrace);
|
|
skip_whitespace!(self);
|
|
let then_block = delimiter_block!(
|
|
self,
|
|
expression,
|
|
Some(RCurlyBrace)
|
|
);
|
|
expect!(self, RCurlyBrace);
|
|
skip_whitespace!(self);
|
|
let else_block = if let Some(Keyword(Kw::Else)) = self.peek() {
|
|
self.next();
|
|
skip_whitespace!(self);
|
|
expect!(self, LCurlyBrace);
|
|
let else_exprs = delimiter_block!(
|
|
self,
|
|
expression,
|
|
Some(RCurlyBrace)
|
|
);
|
|
Some(else_exprs)
|
|
} else {
|
|
None
|
|
};
|
|
expect!(self, RCurlyBrace);
|
|
Ok(Conditional(Box::new(test),
|
|
Box::new(Block(VecDeque::from(then_block))),
|
|
else_block.map(|list| Box::new(Block(VecDeque::from(list))))))
|
|
}
|
|
|
|
fn identifier_expr(&mut self) -> ParseResult<Expression> {
|
|
let name = expect_identifier!(self);
|
|
let expr = match self.peek() {
|
|
Some(LParen) => {
|
|
let args = self.call_expression()?;
|
|
Expression::Call(Callable::NamedFunction(name), args)
|
|
}
|
|
__ => Expression::Variable(name),
|
|
};
|
|
Ok(expr)
|
|
}
|
|
|
|
fn call_expression(&mut self) -> ParseResult<Vec<Expression>> {
|
|
expect!(self, LParen);
|
|
let args: Vec<Expression> = self.exprlist()?;
|
|
expect!(self, RParen);
|
|
Ok(args)
|
|
}
|
|
|
|
fn paren_expr(&mut self) -> ParseResult<Expression> {
|
|
expect!(self, Token::LParen);
|
|
let expr = self.expression()?;
|
|
expect!(self, Token::RParen);
|
|
Ok(expr)
|
|
}
|
|
}
|
|
|
|
pub fn parse(tokens: &[Token], _parsed_tree: &[Statement]) -> ParseResult<AST> {
|
|
let mut parser = Parser::initialize(tokens);
|
|
parser.program()
|
|
}
|
|
|
|
/*
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use schala_lang::tokenizer;
|
|
use super::*;
|
|
use super::Statement::*;
|
|
use super::Expression::*;
|
|
|
|
macro_rules! parsetest {
|
|
($input:expr, $output:pat, $ifexpr:expr) => {
|
|
{
|
|
let tokens = tokenizer::tokenize($input).unwrap();
|
|
let ast = parse(&tokens, &[]).unwrap();
|
|
match &ast[..] {
|
|
$output if $ifexpr => (),
|
|
x => panic!("Error in parse test, got {:?} instead", x)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn function_parse_test() {
|
|
use super::Function;
|
|
parsetest!(
|
|
"fn a() { 1 + 2 }",
|
|
&[FuncDefNode(Function {prototype: Prototype { ref name, ref parameters }, ref body})],
|
|
match &body[..] { &[ExprNode(BinExp(_, box Number(1.0), box Number(2.0)))] => true, _ => false }
|
|
&& **name == "a" && match ¶meters[..] { &[] => true, _ => false }
|
|
);
|
|
|
|
parsetest!(
|
|
"fn a(x,y){ 1 + 2 }",
|
|
&[FuncDefNode(Function {prototype: Prototype { ref name, ref parameters }, ref body})],
|
|
match &body[..] { &[ExprNode(BinExp(_, box Number(1.0), box Number(2.0)))] => true, _ => false }
|
|
&& **name == "a" && *parameters[0] == "x" && *parameters[1] == "y" && parameters.len() == 2
|
|
);
|
|
|
|
let t3 = "fn (x) { x + 2 }";
|
|
let tokens3 = tokenizer::tokenize(t3).unwrap();
|
|
assert!(parse(&tokens3, &[]).is_err());
|
|
}
|
|
|
|
#[test]
|
|
fn expression_parse_test() {
|
|
parsetest!("a", &[ExprNode(Variable(ref s))], **s == "a");
|
|
parsetest!("a + b",
|
|
&[ExprNode(BinExp(BinOp::Add, box Variable(ref a), box Variable(ref b)))],
|
|
**a == "a" && **b == "b");
|
|
parsetest!("a + b * c",
|
|
&[ExprNode(BinExp(BinOp::Add, box Variable(ref a), box BinExp(BinOp::Mul, box Variable(ref b), box Variable(ref c))))],
|
|
**a == "a" && **b == "b" && **c == "c");
|
|
parsetest!("a * b + c",
|
|
&[ExprNode(BinExp(BinOp::Add, box BinExp(BinOp::Mul, box Variable(ref a), box Variable(ref b)), box Variable(ref c)))],
|
|
**a == "a" && **b == "b" && **c == "c");
|
|
parsetest!("(a + b) * c",
|
|
&[ExprNode(BinExp(BinOp::Mul, box BinExp(BinOp::Add, box Variable(ref a), box Variable(ref b)), box Variable(ref c)))],
|
|
**a == "a" && **b == "b" && **c == "c");
|
|
}
|
|
|
|
#[test]
|
|
fn lambda_parse_test() {
|
|
use schala_lang::tokenizer;
|
|
let t1 = "(fn(x) { x + 2 })";
|
|
let tokens1 = tokenizer::tokenize(t1).unwrap();
|
|
match parse(&tokens1, &[]).unwrap()[..] {
|
|
_ => (),
|
|
}
|
|
|
|
let t2 = "fn(x) { x + 2 }";
|
|
let tokens2 = tokenizer::tokenize(t2).unwrap();
|
|
assert!(parse(&tokens2, &[]).is_err());
|
|
|
|
let t3 = "(fn(x) { x + 10 })(20)";
|
|
let tokens3 = tokenizer::tokenize(t3).unwrap();
|
|
match parse(&tokens3, &[]).unwrap() {
|
|
_ => (),
|
|
};
|
|
}
|
|
|
|
#[test]
|
|
fn conditional_parse_test() {
|
|
use schala_lang::tokenizer;
|
|
let t1 = "if null { 20 } else { 40 }";
|
|
let tokens = tokenizer::tokenize(t1).unwrap();
|
|
match parse(&tokens, &[]).unwrap()[..] {
|
|
[ExprNode(Conditional(box Null, box Block(_), Some(box Block(_))))] => (),
|
|
_ => panic!(),
|
|
}
|
|
|
|
let t2 = r"
|
|
if null {
|
|
20
|
|
} else {
|
|
40
|
|
}
|
|
";
|
|
let tokens2 = tokenizer::tokenize(t2).unwrap();
|
|
match parse(&tokens2, &[]).unwrap()[..] {
|
|
[ExprNode(Conditional(box Null, box Block(_), Some(box Block(_))))] => (),
|
|
_ => panic!(),
|
|
}
|
|
|
|
let t2 = r"
|
|
if null {
|
|
20 } else
|
|
{
|
|
40
|
|
}
|
|
";
|
|
let tokens3 = tokenizer::tokenize(t2).unwrap();
|
|
match parse(&tokens3, &[]).unwrap()[..] {
|
|
[ExprNode(Conditional(box Null, box Block(_), Some(box Block(_))))] => (),
|
|
_ => panic!(),
|
|
}
|
|
}
|
|
}
|
|
*/
|