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use crate::ast::*;
use harn_lexer::{Span, TokenKind};
use super::error::ParserError;
use super::expression_nodes::{self as nodes, Expression};
use super::state::Parser;
impl Parser {
pub(super) fn parse_postfix(&mut self) -> Result<Expression, ParserError> {
let expr = Box::new(self.parse_primary()?);
self.parse_postfix_suffixes(expr)
}
fn parse_postfix_suffixes(&mut self, mut expr: Expression) -> Result<Expression, ParserError> {
loop {
if self.check_skip_newlines(&TokenKind::Dot)
|| self.check_skip_newlines(&TokenKind::QuestionDot)
{
let optional = self.check(&TokenKind::QuestionDot);
let start = expr.span;
self.advance();
if optional && self.check(&TokenKind::LBracket) {
self.advance();
let index = self.parse_nested_expression("optional subscript index")?;
self.consume(&TokenKind::RBracket, "]")?;
expr = nodes::expression(
|| Node::OptionalSubscriptAccess {
object: expr,
index: Box::new(index),
},
Span::merge(start, self.prev_span()),
);
continue;
}
let member = self.consume_identifier_or_keyword("member name")?;
if self.check(&TokenKind::LParen) {
self.advance();
let args = self.parse_arg_list()?;
self.consume(&TokenKind::RParen, ")")?;
if optional {
expr = nodes::expression(
|| Node::OptionalMethodCall {
object: expr,
method: member,
args,
},
Span::merge(start, self.prev_span()),
);
} else {
expr = nodes::expression(
|| Node::MethodCall {
object: expr,
method: member,
args,
},
Span::merge(start, self.prev_span()),
);
}
} else if optional {
expr = nodes::expression(
|| Node::OptionalPropertyAccess {
object: expr,
property: member,
},
Span::merge(start, self.prev_span()),
);
} else {
expr = nodes::expression(
|| Node::PropertyAccess {
object: expr,
property: member,
},
Span::merge(start, self.prev_span()),
);
}
} else if self.check(&TokenKind::LBracket) {
let start = expr.span;
self.advance();
// Disambiguate `[:end]` / `[start:end]` / `[start:]` slices from
// `[index]` subscript access.
if self.check(&TokenKind::Colon) {
self.advance();
let end_expr = if self.check(&TokenKind::RBracket) {
None
} else {
Some(Box::new(self.parse_nested_expression("slice bound")?))
};
self.consume(&TokenKind::RBracket, "]")?;
expr = nodes::expression(
|| Node::SliceAccess {
object: expr,
start: None,
end: end_expr,
},
Span::merge(start, self.prev_span()),
);
} else {
let index = self.parse_nested_expression("subscript index")?;
if self.check(&TokenKind::Colon) {
self.advance();
let end_expr = if self.check(&TokenKind::RBracket) {
None
} else {
Some(Box::new(self.parse_nested_expression("slice bound")?))
};
self.consume(&TokenKind::RBracket, "]")?;
expr = nodes::expression(
|| Node::SliceAccess {
object: expr,
start: Some(Box::new(index)),
end: end_expr,
},
Span::merge(start, self.prev_span()),
);
} else {
self.consume(&TokenKind::RBracket, "]")?;
expr = nodes::expression(
|| Node::SubscriptAccess {
object: expr,
index: Box::new(index),
},
Span::merge(start, self.prev_span()),
);
}
}
} else if self.check(&TokenKind::LBrace) {
let struct_name = match &expr.node {
Node::Identifier(name) if self.is_struct_construct_lookahead(name) => {
Some(name.clone())
}
_ => None,
};
let Some(struct_name) = struct_name else {
break;
};
let start = expr.span;
self.advance();
let dict = self.parse_dict_literal(start)?;
let fields = match dict.node {
Node::DictLiteral(fields) => fields,
_ => unreachable!("dict parser must return a dict literal"),
};
expr = nodes::expression(
|| Node::StructConstruct {
struct_name,
fields,
},
dict.span,
);
} else if self.check(&TokenKind::Lt) && matches!(expr.node, Node::Identifier(_)) {
let saved_pos = self.pos;
let start = expr.span;
self.advance();
let parsed_type_args = self.parse_type_arg_list();
if let Ok(type_args) = parsed_type_args {
if self.check(&TokenKind::LParen) {
self.advance();
let args = self.parse_arg_list()?;
self.consume(&TokenKind::RParen, ")")?;
if let Node::Identifier(name) = expr.node {
expr = nodes::expression(
|| Node::FunctionCall {
name,
type_args,
args,
},
Span::merge(start, self.prev_span()),
);
}
} else {
self.pos = saved_pos;
break;
}
} else {
self.pos = saved_pos;
break;
}
} else if self.check(&TokenKind::LParen) {
let start = expr.span;
self.advance();
let args = self.parse_arg_list()?;
self.consume(&TokenKind::RParen, ")")?;
if let Node::Identifier(name) = &expr.node {
let name = name.clone();
expr = nodes::expression(
|| Node::FunctionCall {
name,
type_args: Vec::new(),
args,
},
Span::merge(start, self.prev_span()),
);
} else {
expr = nodes::expression(
|| Node::ValueCall { callee: expr, args },
Span::merge(start, self.prev_span()),
);
}
} else if self.check(&TokenKind::Question) {
// Disambiguate `?[index]` (legacy optional subscript), `expr?`
// (postfix try), and `expr ? a : b` (ternary).
if self.question_starts_ternary_branch() {
break;
}
if matches!(self.peek_kind_at(1), Some(TokenKind::LBracket)) {
let start = expr.span;
self.advance(); // consume ?
self.advance(); // consume [
let index = self.parse_nested_expression("optional subscript index")?;
self.consume(&TokenKind::RBracket, "]")?;
expr = nodes::expression(
|| Node::OptionalSubscriptAccess {
object: expr,
index: Box::new(index),
},
Span::merge(start, self.prev_span()),
);
continue;
}
let start = expr.span;
self.advance();
expr = nodes::expression(
|| Node::TryOperator { operand: expr },
Span::merge(start, self.prev_span()),
);
} else if self.check(&TokenKind::Not) {
// Postfix `!` is the non-null assertion. A `!` following a
// primary can only be this: `!=` is a single `Neq` token and
// prefix `!` (logical not) is parsed at the start of a unary,
// never reached here.
let start = expr.span;
self.advance();
expr = nodes::expression(
|| Node::NonNullAssert { operand: expr },
Span::merge(start, self.prev_span()),
);
} else {
break;
}
}
Ok(expr)
}
fn question_starts_ternary_branch(&self) -> bool {
// Look at the first non-newline token after `?`. A ternary may wrap
// its true-branch onto a new line (`cond ?\n value : other`), so a
// newline immediately after `?` must not cause us to misclassify this
// as a postfix-`?`.
let next = self
.tokens
.iter()
.skip(self.pos + 1)
.find(|t| t.kind != TokenKind::Newline)
.map(|t| &t.kind);
next.is_some_and(Self::token_starts_ternary_branch)
&& self.question_has_top_level_ternary_colon()
}
fn token_starts_ternary_branch(kind: &TokenKind) -> bool {
matches!(
kind,
TokenKind::Identifier(_)
| TokenKind::IntLiteral(_)
| TokenKind::FloatLiteral(_)
| TokenKind::StringLiteral(_)
| TokenKind::RawStringLiteral(_)
| TokenKind::InterpolatedString(_)
| TokenKind::True
| TokenKind::False
| TokenKind::Nil
| TokenKind::LParen
| TokenKind::LBracket
| TokenKind::LBrace
| TokenKind::Not
| TokenKind::Minus
| TokenKind::Fn
| TokenKind::If
| TokenKind::Match
| TokenKind::Try
| TokenKind::Spawn
| TokenKind::Parallel
| TokenKind::Retry
| TokenKind::DurationLiteral(_)
)
}
fn question_has_top_level_ternary_colon(&self) -> bool {
let mut delimiter_depth = 0usize;
// True when the most recent significant top-level token was `?` or
// `:` — i.e. we're scanning for the start of a branch and a newline
// here is just a wrap, not an end-of-ternary.
let mut at_branch_start = true;
for (pos, token) in self.tokens.iter().enumerate().skip(self.pos + 1) {
if delimiter_depth == 0 {
match token.kind {
TokenKind::Colon => return true,
TokenKind::Newline => {
if at_branch_start {
// `?` (or `:`) was the last significant token; this
// newline simply wraps the branch onto a new line.
continue;
}
if self.next_non_newline_continues_ternary_branch(pos + 1) {
continue;
}
return false;
}
TokenKind::RParen
| TokenKind::RBracket
| TokenKind::RBrace
| TokenKind::Eof => {
return false;
}
_ => {
at_branch_start = false;
}
}
}
match token.kind {
TokenKind::LParen | TokenKind::LBracket | TokenKind::LBrace => {
delimiter_depth += 1;
}
TokenKind::RParen | TokenKind::RBracket | TokenKind::RBrace => {
delimiter_depth = delimiter_depth.saturating_sub(1);
}
TokenKind::Eof => return false,
_ => {}
}
}
false
}
fn next_non_newline_continues_ternary_branch(&self, start_pos: usize) -> bool {
let Some(kind) = self
.tokens
.iter()
.skip(start_pos)
.find(|token| token.kind != TokenKind::Newline)
.map(|token| &token.kind)
else {
return false;
};
matches!(
kind,
TokenKind::Colon
| TokenKind::Plus
| TokenKind::Star
| TokenKind::Slash
| TokenKind::Percent
| TokenKind::Pow
| TokenKind::And
| TokenKind::Or
| TokenKind::Eq
| TokenKind::Neq
| TokenKind::Lt
| TokenKind::Gt
| TokenKind::Lte
| TokenKind::Gte
| TokenKind::NilCoal
| TokenKind::Pipe
| TokenKind::Dot
| TokenKind::QuestionDot
)
}
}