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use crate::{language::PythonLanguage, lexer::PythonTokenType, parser::PythonElementType as ET};
use oak_core::{
Source,
parser::{GreenNode, ParserState},
};
/// Python parser state.
pub(crate) type State<'a, S> = ParserState<'a, PythonLanguage, S>;
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum Associativity {
Left,
Right,
None,
}
impl<'config> super::PythonParser<'config> {
pub(crate) fn parse_expression<'a, S: Source + ?Sized>(&self, state: &mut State<'a, S>, min_prec: u8) {
let mut left = self.primary(state);
loop {
self.skip_trivia(state);
let kind = match state.peek_kind() {
Some(k) => k,
None => break,
};
let (prec, assoc) = match self.get_infix_prec(kind) {
Some(p) => p,
None => break,
};
if prec < min_prec {
break;
}
left = self.infix(state, left, prec, assoc).unwrap_or(left);
}
}
fn primary<'a, S: Source + ?Sized>(&self, state: &mut State<'a, S>) -> &'a GreenNode<'a, PythonLanguage> {
use PythonTokenType::*;
self.skip_trivia(state);
let cp = state.checkpoint();
let kind = state.peek_kind();
match kind {
Some(Identifier) => {
state.bump();
state.finish_at(cp, ET::Name)
}
Some(Number) | Some(String) | Some(Bytes) | Some(TrueKeyword) | Some(FalseKeyword) | Some(NoneKeyword) => {
state.bump();
state.finish_at(cp, ET::Constant)
}
Some(LeftParen) => {
state.bump();
self.skip_trivia(state);
if state.at(RightParen) {
state.bump();
state.finish_at(cp, ET::Tuple)
}
else {
self.parse_expression(state, 0);
self.skip_trivia(state);
if state.at(ForKeyword) {
self.parse_comprehension(state);
state.expect(RightParen).ok();
state.finish_at(cp, ET::GeneratorExp)
}
else if state.at(Comma) {
while state.at(Comma) {
state.bump();
self.skip_trivia(state);
if state.at(RightParen) {
break;
}
self.parse_expression(state, 0);
self.skip_trivia(state);
}
state.expect(RightParen).ok();
state.finish_at(cp, ET::Tuple)
}
else {
state.expect(RightParen).ok();
state.finish_at(cp, ET::Expr)
}
}
}
Some(LeftBracket) => {
state.bump();
self.skip_trivia(state);
if state.at(RightBracket) {
state.bump();
state.finish_at(cp, ET::List)
}
else {
self.parse_expression(state, 0);
self.skip_trivia(state);
if state.at(ForKeyword) {
self.parse_comprehension(state);
state.expect(RightBracket).ok();
state.finish_at(cp, ET::ListComp)
}
else {
while state.at(Comma) {
state.bump();
self.skip_trivia(state);
if state.at(RightBracket) {
break;
}
self.parse_expression(state, 0);
self.skip_trivia(state);
}
state.expect(RightBracket).ok();
state.finish_at(cp, ET::List)
}
}
}
Some(LeftBrace) => {
state.bump();
self.skip_trivia(state);
if state.at(RightBrace) {
state.bump();
state.finish_at(cp, ET::Dict)
}
else {
// Could be set or dict
self.parse_expression(state, 0);
self.skip_trivia(state);
if state.at(Colon) {
// Dict
state.bump();
self.parse_expression(state, 0);
self.skip_trivia(state);
if state.at(ForKeyword) {
self.parse_comprehension(state);
state.expect(RightBrace).ok();
state.finish_at(cp, ET::DictComp)
}
else {
while state.at(Comma) {
state.bump();
self.skip_trivia(state);
if state.at(RightBrace) {
break;
}
self.parse_expression(state, 0);
self.skip_trivia(state);
state.expect(Colon).ok();
self.parse_expression(state, 0);
self.skip_trivia(state);
}
state.expect(RightBrace).ok();
state.finish_at(cp, ET::Dict)
}
}
else if state.at(ForKeyword) {
// Set comprehension
self.parse_comprehension(state);
state.expect(RightBrace).ok();
state.finish_at(cp, ET::SetComp)
}
else {
// Set
while state.at(Comma) {
state.bump();
self.skip_trivia(state);
if state.at(RightBrace) {
break;
}
self.parse_expression(state, 0);
self.skip_trivia(state);
}
state.expect(RightBrace).ok();
state.finish_at(cp, ET::Set)
}
}
}
Some(Plus) | Some(Minus) | Some(Tilde) | Some(NotKeyword) | Some(AwaitKeyword) => {
state.bump();
self.parse_expression(state, 12); // Unary op prec
if kind == Some(AwaitKeyword) { state.finish_at(cp, ET::Await) } else { state.finish_at(cp, ET::UnaryOp) }
}
Some(LambdaKeyword) => {
state.bump();
// parse params
self.skip_trivia(state);
if !state.at(Colon) {
loop {
state.expect(Identifier).ok();
self.skip_trivia(state);
if !state.eat(Comma) {
break;
}
self.skip_trivia(state);
}
}
state.expect(Colon).ok();
self.parse_expression(state, 0);
state.finish_at(cp, ET::Lambda)
}
_ => {
state.bump();
state.finish_at(cp, ET::Error)
}
}
}
fn get_infix_prec(&self, kind: PythonTokenType) -> Option<(u8, Associativity)> {
use PythonTokenType::*;
match kind {
Plus | Minus => Some((10, Associativity::Left)),
Star | Slash | Percent | DoubleSlash => Some((11, Associativity::Left)),
DoubleStar => Some((13, Associativity::Right)),
Equal | NotEqual | Less | LessEqual | Greater | GreaterEqual | InKeyword | IsKeyword | NotKeyword => Some((5, Associativity::Left)),
AndKeyword => Some((3, Associativity::Left)),
OrKeyword => Some((2, Associativity::Left)),
Assign | PlusAssign | MinusAssign | StarAssign | SlashAssign => Some((1, Associativity::None)),
Dot | LeftParen | LeftBracket => Some((15, Associativity::Left)),
_ => None,
}
}
fn infix<'a, S: Source + ?Sized>(&self, state: &mut State<'a, S>, _left: &'a GreenNode<'a, PythonLanguage>, prec: u8, assoc: Associativity) -> Option<&'a GreenNode<'a, PythonLanguage>> {
use PythonTokenType::*;
let cp = state.checkpoint_before(_left);
let kind = state.peek_kind()?;
match kind {
LeftParen => {
state.bump(); // Consume LeftParen
self.skip_trivia(state);
while !state.at(RightParen) && !state.at(Eof) {
self.parse_expression(state, 0);
self.skip_trivia(state);
if !state.eat(Comma) {
break;
}
}
self.skip_trivia(state);
state.expect(RightParen).ok();
Some(state.finish_at(cp, ET::Call))
}
LeftBracket => {
state.bump(); // Consume LeftBracket
let cp_slice = state.checkpoint();
let mut is_slice = false;
if state.at(Colon) {
is_slice = true;
}
else {
self.parse_expression(state, 0);
self.skip_trivia(state);
if state.at(Colon) {
is_slice = true;
}
}
if is_slice {
// It's a slice
while state.at(Colon) {
state.bump();
self.skip_trivia(state);
if !state.at(Colon) && !state.at(RightBracket) {
self.parse_expression(state, 0);
self.skip_trivia(state);
}
}
state.finish_at(cp_slice, ET::Slice);
}
state.expect(RightBracket).ok();
Some(state.finish_at(cp, ET::Subscript))
}
Dot => {
state.bump(); // Consume Dot
self.skip_trivia(state);
state.expect(Identifier).ok();
Some(state.finish_at(cp, ET::Attribute))
}
_ => {
let result_kind = if prec == 1 {
ET::AssignStmt
}
else if prec <= 3 {
ET::BoolOp
}
else if prec == 5 {
ET::Compare
}
else {
ET::BinOp
};
state.bump(); // Consume operator
let next_prec = match assoc {
Associativity::Left => prec + 1,
Associativity::Right => prec,
Associativity::None => prec + 1,
};
self.parse_expression(state, next_prec);
Some(state.finish_at(cp, result_kind.into()))
}
}
}
}