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parser.rs
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/
parser.rs
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use crate::{
fun::{
parser::{is_num_char, Indent, ParseResult, ParserCommons},
CtrField, Name, Num, Op, STRINGS,
},
imp::{AssignPattern, Definition, Enum, Expr, InPlaceOp, MatchArm, Stmt, Variant},
maybe_grow,
};
use TSPL::Parser;
use super::RepeatedNames;
pub struct PyParser<'i> {
pub input: &'i str,
pub index: usize,
}
impl<'a> PyParser<'a> {
pub fn new(input: &'a str) -> Self {
Self { input, index: 0 }
}
}
impl<'a> ParserCommons<'a> for PyParser<'a> {}
impl<'a> Parser<'a> for PyParser<'a> {
fn input(&mut self) -> &'a str {
self.input
}
fn index(&mut self) -> &mut usize {
&mut self.index
}
/// Generates an error message for parsing failures, including the highlighted context.
///
/// Override to have our own error message.
fn expected<T>(&mut self, exp: &str) -> ParseResult<T> {
let ini_idx = *self.index();
let end_idx = *self.index() + 1;
self.expected_spanned(exp, ini_idx..end_idx)
}
/// Consumes an instance of the given string, erroring if it is not found.
///
/// Override to have our own error message.
fn consume(&mut self, text: &str) -> ParseResult<()> {
self.skip_trivia();
if self.input().get(*self.index()..).unwrap_or_default().starts_with(text) {
*self.index() += text.len();
Ok(())
} else {
self.expected(format!("'{text}'").as_str())
}
}
fn skip_trivia(&mut self) {
while let Some(c) = self.peek_one() {
if c.is_ascii_whitespace() {
self.advance_one();
continue;
}
if c == '#' {
while let Some(c) = self.peek_one() {
if c != '\n' {
self.advance_one();
} else {
break;
}
}
self.advance_one(); // Skip the newline character as well
continue;
}
break;
}
}
}
impl<'a> PyParser<'a> {
/// <var> <postfix>?
///
fn parse_primary_expr(&mut self, inline: bool) -> ParseResult<Expr> {
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
if self.try_parse_keyword("lambda") | self.try_consume_exactly("λ") {
fn parse_lam_var(p: &mut PyParser) -> ParseResult<(Name, bool)> {
if p.starts_with("$") {
p.advance_one();
Ok((p.parse_bend_name()?, true))
} else {
Ok((p.parse_bend_name()?, false))
}
}
let names = self.list_like(|p| parse_lam_var(p), "", ":", ",", false, 1)?;
let bod = self.parse_expr(inline, true)?;
Ok(Expr::Lam { names, bod: Box::new(bod) })
} else if self.starts_with("(") {
self.advance_one();
let expr = self.parse_expr(inline, true)?;
self.consume(")")?;
Ok(expr)
} else if self.starts_with("{") {
// Map or Sup
self.parse_map_or_sup()
} else if self.starts_with("[") {
// List or Comprehension
self.parse_list_or_comprehension()
} else if self.starts_with("![") {
// Tree Node
self.parse_tree_node()
} else if self.starts_with("!") {
// Tree Leaf
self.parse_tree_leaf(inline)
} else if self.starts_with("`") {
// Symbol
Ok(Expr::Num { val: Num::U24(self.parse_quoted_symbol()?) })
} else if self.starts_with("\"") {
// String
Ok(Expr::Str { val: STRINGS.get(self.parse_quoted_string()?) })
} else if self.starts_with("'") {
// Char
Ok(Expr::Num { val: Num::U24(self.parse_quoted_char()? as u32 & 0x00ff_ffff) })
} else if self.starts_with("$") {
// Unscoped var
self.advance_one();
Ok(Expr::Chn { nam: self.parse_bend_name()? })
} else if self.starts_with("*") {
// Era
self.advance_one();
Ok(Expr::Era)
} else if let Some(c) = self.peek_one() {
if is_num_char(c) {
// Number
Ok(Expr::Num { val: self.parse_number()? })
} else {
// Var
let nam = self.labelled(|p| p.parse_bend_name(), "expression")?;
Ok(Expr::Var { nam })
}
} else {
self.expected("expression")?
}
}
fn call_or_postfix(&mut self, inline: bool) -> ParseResult<Expr> {
let ini_idx = *self.index();
let base = self.parse_primary_expr(inline)?;
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
// call
if self.starts_with("(") {
self.advance_one();
let mut args = Vec::new();
let mut kwargs = Vec::new();
let mut must_be_named = false;
while !self.starts_with(")") {
let ini_idx = *self.index();
let (bnd, arg) = self.parse_named_arg()?;
let end_idx = *self.index();
if let Some(bnd) = bnd {
must_be_named = true;
kwargs.push((bnd, arg));
} else if must_be_named {
let msg = "Positional arguments are not allowed to go after named arguments.".to_string();
return self.with_ctx(Err(msg), ini_idx..end_idx);
} else {
args.push(arg);
}
if self.starts_with(",") {
self.consume(",")?;
} else {
break;
}
}
self.consume(")")?;
if args.is_empty() && kwargs.is_empty() {
return Ok(base);
} else {
return Ok(Expr::Call { fun: Box::new(base), args, kwargs });
}
}
// map get
if self.starts_with("[") {
if let Expr::Var { nam } = base {
self.advance_one();
let key = self.parse_expr(inline, false)?;
self.consume("]")?;
return Ok(Expr::MapGet { nam, key: Box::new(key) });
} else {
let end_idx = *self.index();
return self.expected_spanned("Map variable name", ini_idx..end_idx);
}
}
// ctr
if self.starts_with("{") {
if let Expr::Var { nam } = base {
let kwargs = self.list_like(|p| p.data_kwarg(), "{", "}", ",", true, 0)?;
return Ok(Expr::Ctr { name: nam, args: Vec::new(), kwargs });
} else {
let end_idx = *self.index();
return self.expected_spanned("Constructor name", ini_idx..end_idx);
}
}
// no postfix
Ok(base)
}
fn parse_map_or_sup(&mut self) -> ParseResult<Expr> {
self.advance_one();
// Empty map
if self.try_consume("}") {
return Ok(Expr::Map { entries: vec![] });
}
let head = self.parse_expr(false, false)?;
self.skip_trivia();
if self.try_consume(",") {
self.parse_sup(head)
} else if self.try_consume(":") {
self.parse_map_init(head)
} else {
self.expected("',' or ':'")
}
}
fn parse_map_init(&mut self, head: Expr) -> ParseResult<Expr> {
let mut entries = Vec::new();
let val = self.parse_expr(false, false)?;
entries.push((head, val));
self.skip_trivia();
if !self.starts_with("}") {
self.consume(",")?;
}
let tail = self.list_like(|p| p.parse_map_entry(), "", "}", ",", true, 0)?;
entries.extend(tail);
Ok(Expr::Map { entries })
}
fn parse_sup(&mut self, head: Expr) -> ParseResult<Expr> {
let mut els = vec![head];
let tail = self.list_like(|p| p.parse_expr(false, false), "", "}", ",", true, 1)?;
els.extend(tail);
Ok(Expr::Sup { els })
}
fn parse_tree_node(&mut self) -> ParseResult<Expr> {
self.advance_one();
self.advance_one();
let left = self.parse_expr(false, false)?;
self.consume(",")?;
let right = self.parse_expr(false, false)?;
self.consume("]")?;
Ok(Expr::TreeNode { left: Box::new(left), right: Box::new(right) })
}
fn parse_tree_leaf(&mut self, inline: bool) -> ParseResult<Expr> {
self.advance_one();
let val = self.parse_expr(inline, false)?;
Ok(Expr::TreeLeaf { val: Box::new(val) })
}
fn data_kwarg(&mut self) -> ParseResult<(Name, Expr)> {
self.skip_trivia();
let nam = self.parse_bend_name()?;
self.consume(":")?;
let expr = self.parse_expr(false, false)?;
Ok((nam, expr))
}
fn parse_map_entry(&mut self) -> ParseResult<(Expr, Expr)> {
let key = self.parse_expr(false, false)?;
self.consume(":")?;
let val = self.parse_expr(false, false)?;
Ok((key, val))
}
fn parse_list_or_comprehension(&mut self) -> ParseResult<Expr> {
self.consume_exactly("[")?;
// Empty list
self.skip_trivia();
if self.try_consume_exactly("]") {
return Ok(Expr::Lst { els: vec![] });
}
let head = self.parse_expr(false, false)?;
self.skip_trivia();
if self.try_parse_keyword("for") {
// Comprehension
self.skip_trivia();
let bind = self.parse_bend_name()?;
self.skip_trivia();
self.parse_keyword("in")?;
let iter = self.parse_expr(false, false)?;
let mut cond = None;
self.skip_trivia();
if self.try_parse_keyword("if") {
cond = Some(Box::new(self.parse_expr(false, false)?));
}
self.consume("]")?;
Ok(Expr::LstMap { term: Box::new(head), bind, iter: Box::new(iter), cond })
} else {
// List
let mut head = vec![head];
self.skip_trivia();
if !self.starts_with("]") {
self.consume(",")?;
}
let tail = self.list_like(|p| p.parse_expr(false, false), "", "]", ",", true, 0)?;
head.extend(tail);
Ok(Expr::Lst { els: head })
}
}
/// "λ" (<name> ","?)+ ":" <expr>
/// | "open" <type> ":" <var>
/// | <infix>
fn parse_expr(&mut self, inline: bool, tup: bool) -> ParseResult<Expr> {
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
let base = self.parse_infix_expr(0, inline)?;
if !tup {
return Ok(base);
}
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
if self.starts_with(",") {
let mut els = vec![base];
loop {
if self.starts_with(",") {
self.advance_one();
els.push(self.parse_expr(inline, false)?);
if self.starts_with("\n") {
break;
}
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
} else {
break;
}
}
Ok(Expr::Tup { els })
} else {
Ok(base)
}
}
/// Named argument of a function call.
fn parse_named_arg(&mut self) -> ParseResult<(Option<Name>, Expr)> {
let arg = self.parse_expr(false, false)?;
if self.try_consume("=") {
if let Expr::Var { nam } = arg {
let bind = Some(nam);
let arg = self.parse_expr(false, false)?;
Ok((bind, arg))
} else {
let msg = "Unexpected '=' in unnamed argument.".to_string();
let idx = *self.index();
self.with_ctx(Err(msg), idx..idx + 1)
}
} else {
Ok((None, arg))
}
}
/// Infix expression.
/// <simple> (<infix_op> <infix>)?
fn parse_infix_expr(&mut self, prec: usize, inline: bool) -> ParseResult<Expr> {
maybe_grow(|| {
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
if prec > Op::max_precedence() {
return self.call_or_postfix(inline);
}
let mut lhs = self.parse_infix_expr(prec + 1, inline)?;
if inline {
self.skip_trivia_inline()?;
} else {
self.skip_trivia();
}
while let Some(op) = self.peek_oper() {
if op.precedence() == prec {
self.try_parse_oper().unwrap();
let rhs = self.parse_infix_expr(prec + 1, inline)?;
lhs = Expr::Opr { op, lhs: Box::new(lhs), rhs: Box::new(rhs) };
self.skip_trivia_inline()?;
} else {
break;
}
}
Ok(lhs)
})
}
fn consume_indent_at_most(&mut self, expected: Indent) -> ParseResult<Indent> {
let got = self.advance_newlines()?;
match (expected, got) {
(_, Indent::Eof) => Ok(Indent::Eof),
(Indent::Val(expected), Indent::Val(got)) if got <= expected => Ok(Indent::Val(got)),
(expected, got) => self.expected_indent(expected, got),
}
}
fn consume_indent_exactly(&mut self, expected: Indent) -> ParseResult<()> {
let got = self.advance_newlines()?;
match (expected, got) {
(Indent::Eof, Indent::Eof) => Ok(()),
(Indent::Val(expected), Indent::Val(got)) if got == expected => Ok(()),
(expected, got) => self.expected_indent(expected, got),
}
}
/// Parses a statement and returns the indentation of the next statement.
fn parse_statement(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
maybe_grow(|| {
if self.try_parse_keyword("return") {
self.parse_return()
} else if self.try_parse_keyword("def") {
self.parse_local_def(indent)
} else if self.try_parse_keyword("if") {
self.parse_if(indent)
} else if self.try_parse_keyword("match") {
self.parse_match(indent)
} else if self.try_parse_keyword("switch") {
self.parse_switch(indent)
} else if self.try_parse_keyword("fold") {
self.parse_fold(indent)
} else if self.try_parse_keyword("bend") {
self.parse_bend(indent)
} else if self.try_parse_keyword("with") {
self.parse_with(indent)
} else if self.try_parse_keyword("open") {
self.parse_open(indent)
} else if self.try_parse_keyword("use") {
self.parse_use(indent)
} else {
self.parse_assign(indent)
}
})
}
/// Assignments, monadic bind operations and in-place operations.
/// <assign_pattern> "=" <expr> ";"?
/// | <assign_pattern> "<-" <expr> ";"?
///
fn parse_assign(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
let ini_idx = *self.index();
let pat = self.parse_assign_pattern()?;
let end_idx = *self.index();
self.skip_trivia_inline()?;
// Assignment
if self.starts_with("=") {
self.advance_one();
let val = self.parse_expr(true, true)?;
self.skip_trivia_inline()?;
self.try_consume_exactly(";");
if !self.is_eof() {
self.consume_new_line()?;
}
let nxt_indent = self.advance_newlines()?;
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Assign { pat, val: Box::new(val), nxt: Some(Box::new(nxt)) };
return Ok((stmt, nxt_indent));
} else {
let stmt = Stmt::Assign { pat, val: Box::new(val), nxt: None };
return Ok((stmt, nxt_indent));
}
}
// Ask
if self.starts_with("<-") {
self.consume("<-")?;
let val = self.parse_expr(true, true)?;
self.skip_trivia_inline()?;
self.try_consume_exactly(";");
self.consume_indent_exactly(*indent)?;
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Ask { pat, val: Box::new(val), nxt: Box::new(nxt) };
return Ok((stmt, nxt_indent));
}
// In-place
match &pat {
AssignPattern::Var(..) => {}
AssignPattern::MapSet(..) => {}
_ => self.expected_spanned("Var or Map accessor", ini_idx..end_idx)?,
}
if let Some(op) = self.parse_in_place_op()? {
let val = self.parse_expr(true, false)?;
self.skip_trivia_inline()?;
self.try_consume_exactly(";");
self.consume_indent_exactly(*indent)?;
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::InPlace { op, pat: Box::new(pat), val: Box::new(val), nxt: Box::new(nxt) };
return Ok((stmt, nxt_indent));
}
self.expected_spanned("statement", ini_idx..end_idx)
}
fn parse_in_place_op(&mut self) -> ParseResult<Option<InPlaceOp>> {
self.skip_trivia_inline()?;
let op = if self.starts_with("+=") {
self.consume("+=")?;
Some(InPlaceOp::Add)
} else if self.starts_with("-=") {
self.consume("-=")?;
Some(InPlaceOp::Sub)
} else if self.starts_with("*=") {
self.consume("*=")?;
Some(InPlaceOp::Mul)
} else if self.starts_with("/=") {
self.consume("/=")?;
Some(InPlaceOp::Div)
} else if self.starts_with("&=") {
self.consume("&=")?;
Some(InPlaceOp::And)
} else if self.starts_with("|=") {
self.consume("|=")?;
Some(InPlaceOp::Or)
} else if self.starts_with("^=") {
self.consume("^=")?;
Some(InPlaceOp::Xor)
} else if self.starts_with("@=") {
self.consume("@=")?;
Some(InPlaceOp::Map)
} else {
None
};
Ok(op)
}
fn parse_return(&mut self) -> ParseResult<(Stmt, Indent)> {
let term = self.parse_expr(true, true)?;
self.skip_trivia_inline()?;
self.try_consume_exactly(";");
if !self.is_eof() {
self.consume_new_line()?;
}
let indent = self.advance_newlines()?;
Ok((Stmt::Return { term: Box::new(term) }, indent))
}
fn parse_if(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
let cond = self.parse_expr(true, false)?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (then, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
if nxt_indent != *indent {
return self
.expected_indent(*indent, nxt_indent)
.or(self.expected_spanned("'else' or 'elif'", self.index..self.index + 1));
}
let mut elifs = Vec::new();
while self.try_parse_keyword("elif") {
let cond = self.parse_expr(true, false)?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (then, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
if nxt_indent != *indent {
return self
.expected_indent(*indent, nxt_indent)
.or(self.expected_spanned("'else' or 'elif'", self.index..self.index + 1));
}
elifs.push((cond, then));
}
self.parse_keyword("else")?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (otherwise, nxt_indent) = self.parse_statement(indent)?;
let otherwise = elifs.into_iter().rfold(otherwise, |acc, (cond, then)| Stmt::If {
cond: Box::new(cond),
then: Box::new(then),
otherwise: Box::new(acc),
nxt: None,
});
indent.exit_level();
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::If {
cond: Box::new(cond),
then: Box::new(then),
otherwise: Box::new(otherwise),
nxt: Some(Box::new(nxt)),
};
Ok((stmt, nxt_indent))
} else {
let stmt =
Stmt::If { cond: Box::new(cond), then: Box::new(then), otherwise: Box::new(otherwise), nxt: None };
Ok((stmt, nxt_indent))
}
}
fn parse_match(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
let (bnd, arg) = self.parse_match_arg()?;
self.skip_trivia_inline()?;
let (with_bnd, with_arg) = self.parse_with_clause()?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent).or(self.expected_spanned("'case'", self.index..self.index + 1))?;
let (case, mut nxt_indent) = self.parse_match_case(indent)?;
let mut arms = vec![case];
while nxt_indent == *indent {
let (case, nxt_indent_) = self.parse_match_case(indent)?;
nxt_indent = nxt_indent_;
arms.push(case);
}
indent.exit_level();
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Match { arg: Box::new(arg), bnd, with_bnd, with_arg, arms, nxt: Some(Box::new(nxt)) };
Ok((stmt, nxt_indent))
} else {
let stmt = Stmt::Match { arg: Box::new(arg), bnd, with_bnd, with_arg, arms, nxt: None };
Ok((stmt, nxt_indent))
}
}
fn parse_match_arg(&mut self) -> ParseResult<(Option<Name>, Expr)> {
let ini_idx = *self.index();
let arg = self.parse_expr(true, false)?;
let end_idx = *self.index();
self.skip_trivia_inline()?;
match (arg, self.starts_with("=")) {
(Expr::Var { nam }, true) => {
self.advance_one();
Ok((Some(nam), self.parse_expr(true, false)?))
}
(_, true) => self.expected_spanned("argument name", ini_idx..end_idx),
(Expr::Var { nam }, false) => Ok((Some(nam.clone()), Expr::Var { nam })),
(arg, false) => Ok((Some(Name::new("%arg")), arg)),
}
}
fn parse_with_clause(&mut self) -> ParseResult<(Vec<Option<Name>>, Vec<Expr>)> {
self.skip_trivia_inline()?;
let res = if self.try_parse_keyword("with") {
self.list_like(|p| p.parse_with_arg(), "", ":", ",", true, 1)?.into_iter().unzip()
} else {
self.consume_exactly(":")?;
(vec![], vec![])
};
Ok(res)
}
fn parse_with_arg(&mut self) -> ParseResult<(Option<Name>, Expr)> {
let bind = self.parse_bend_name()?;
self.skip_trivia_inline()?;
if self.try_consume("=") {
let arg = self.parse_expr(false, false)?;
Ok((Some(bind), arg))
} else {
Ok((Some(bind.clone()), Expr::Var { nam: bind }))
}
}
fn parse_match_case(&mut self, indent: &mut Indent) -> ParseResult<(MatchArm, Indent)> {
self.parse_keyword("case")?;
self.skip_trivia_inline()?;
let pat = if self.try_consume_exactly("_") {
None
} else {
let nam = self.labelled(|p| p.parse_bend_name(), "name or '_'")?;
Some(nam)
};
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (body, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
let stmt = MatchArm { lft: pat, rgt: body };
Ok((stmt, nxt_indent))
}
fn parse_switch(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
let (bnd, arg) = self.parse_match_arg()?;
self.skip_trivia_inline()?;
let (with_bnd, with_arg) = self.parse_with_clause()?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let ini_idx = *self.index();
let (fst_case, fst_stmt, mut nxt_indent) = self.parse_switch_case(indent)?;
let end_idx = *self.index();
if fst_case != Some(0) {
return self.expected_spanned("case 0", ini_idx..end_idx);
}
let mut arms = vec![fst_stmt];
let mut should_continue = fst_case == Some(0);
let mut expected_num = 1;
while should_continue {
if nxt_indent != *indent {
return self
.expected_indent(*indent, nxt_indent)
.or(self.expected_spanned("'case'", self.index..self.index + 1));
}
let (case, stmt, nxt_indent_) = self.parse_switch_case(indent)?;
nxt_indent = nxt_indent_;
if let Some(case) = case {
if case != expected_num {
return self.expected(&format!("case {}", expected_num));
}
should_continue = true;
arms.push(stmt);
expected_num += 1;
} else {
should_continue = false;
arms.push(stmt);
}
}
indent.exit_level();
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Switch { arg: Box::new(arg), bnd, with_bnd, with_arg, arms, nxt: Some(Box::new(nxt)) };
Ok((stmt, nxt_indent))
} else {
let stmt = Stmt::Switch { arg: Box::new(arg), bnd, with_bnd, with_arg, arms, nxt: None };
Ok((stmt, nxt_indent))
}
}
fn parse_switch_case(&mut self, indent: &mut Indent) -> ParseResult<(Option<u32>, Stmt, Indent)> {
self.parse_keyword("case")?;
self.skip_trivia_inline()?;
let case = if let Some(c) = self.peek_one() {
match c {
'_' => {
self.advance_one();
None
}
c if c.is_ascii_digit() => Some(self.parse_u32()?),
_ => return self.expected("number or '_'"),
}
} else {
return self.expected("number or '_'")?;
};
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (stmt, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
Ok((case, stmt, nxt_indent))
}
/// "fold" <bind> ("=" <arg>)? ":"
/// "case" <ctr> ":"
/// <case>
/// ...
fn parse_fold(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
// Actually identical to match, except the return
let (bind, arg) = self.parse_match_arg()?;
self.skip_trivia_inline()?;
let (with_bnd, with_arg) = self.parse_with_clause()?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent).or(self.expected_spanned("'case'", self.index..self.index + 1))?;
let (case, mut nxt_indent) = self.parse_match_case(indent)?;
let mut arms = vec![case];
while nxt_indent == *indent {
let (case, nxt_indent_) = self.parse_match_case(indent)?;
nxt_indent = nxt_indent_;
arms.push(case);
}
indent.exit_level();
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt =
Stmt::Fold { arg: Box::new(arg), bnd: bind, arms, with_bnd, with_arg, nxt: Some(Box::new(nxt)) };
Ok((stmt, nxt_indent))
} else {
let stmt = Stmt::Fold { arg: Box::new(arg), bnd: bind, arms, with_bnd, with_arg, nxt: None };
Ok((stmt, nxt_indent))
}
}
/// "bend" (<bind> "=" <init> ","?)* ":"
/// "when" <cond> ":"
/// <step>
/// "else" ":"
/// <base>
fn parse_bend(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
let args = self.list_like(|p| p.parse_match_arg(), "", ":", ",", true, 1)?;
let (bind, init) = args.into_iter().unzip();
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent).or(self.expected_spanned("'when'", self.index..self.index + 1))?;
self.parse_keyword("when")?;
let cond = self.parse_expr(true, false)?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (step, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
if nxt_indent != *indent {
return self
.expected_indent(*indent, nxt_indent)
.or(self.expected_spanned("'else'", self.index..self.index + 1));
}
self.parse_keyword("else")?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (base, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
indent.exit_level();
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Bend {
bnd: bind,
arg: init,
cond: Box::new(cond),
step: Box::new(step),
base: Box::new(base),
nxt: Some(Box::new(nxt)),
};
Ok((stmt, nxt_indent))
} else {
let stmt = Stmt::Bend {
bnd: bind,
arg: init,
cond: Box::new(cond),
step: Box::new(step),
base: Box::new(base),
nxt: None,
};
Ok((stmt, nxt_indent))
}
}
/// "with" <typ> ":"
/// <bod>
/// <nxt>?
fn parse_with(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
self.skip_trivia_inline()?;
let typ = self.parse_bend_name()?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
self.consume_new_line()?;
indent.enter_level();
self.consume_indent_exactly(*indent)?;
let (bod, nxt_indent) = self.parse_statement(indent)?;
indent.exit_level();
if nxt_indent == *indent {
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::With { typ, bod: Box::new(bod), nxt: Some(Box::new(nxt)) };
Ok((stmt, nxt_indent))
} else {
let stmt = Stmt::With { typ, bod: Box::new(bod), nxt: None };
Ok((stmt, nxt_indent))
}
}
/// <pat1>
/// | <nam> "[" <expr> "]"
/// | <pat1> ("," <pat1>)*
fn parse_assign_pattern(&mut self) -> ParseResult<AssignPattern> {
let head_ini = *self.index();
let head = self.parse_primary_assign_pattern()?;
let head_end = *self.index();
self.skip_trivia_inline()?;
if self.starts_with("[") {
// TODO: allow patterns like `x[a][b]`
self.advance_one();
let key = self.parse_expr(false, false)?;
self.consume("]")?;
if let AssignPattern::Var(var) = head {
Ok(AssignPattern::MapSet(var, key))
} else {
self.with_ctx(Err("Expected a variable pattern"), head_ini..head_end)
}
} else if self.starts_with(",") {
let mut els = vec![head];
while self.try_consume(",") {
self.skip_trivia_inline()?;
els.push(self.parse_primary_assign_pattern()?);
}
Ok(AssignPattern::Tup(els))
} else {
Ok(head)
}
}
/// "*"
/// | "{"<pat1> ("," <pat1>)+ "}"
/// | "$" <nam>
/// | "(" <pat0> ")"
/// | <nam>
fn parse_primary_assign_pattern(&mut self) -> ParseResult<AssignPattern> {
if self.starts_with("*") {
self.advance_one();
Ok(AssignPattern::Eraser)
} else if self.starts_with("{") {
let binds = self.list_like(|p| p.parse_primary_assign_pattern(), "{", "}", ",", true, 2)?;
Ok(AssignPattern::Sup(binds))
} else if self.starts_with("$") {
self.advance_one();
self.skip_trivia_inline()?;
let nam = self.parse_bend_name()?;
Ok(AssignPattern::Chn(nam))
} else if self.starts_with("(") {
self.advance_one();
let assign = self.parse_assign_pattern()?;
self.consume(")")?;
Ok(assign)
} else {
Ok(AssignPattern::Var(self.parse_bend_name()?))
}
}
/// "open" {typ} ":" {var} ";"? {nxt}
fn parse_open(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
self.skip_trivia_inline()?;
let typ = self.labelled(|p| p.parse_bend_name(), "type name")?;
self.skip_trivia_inline()?;
self.consume_exactly(":")?;
self.skip_trivia_inline()?;
let var = self.labelled(|p| p.parse_bend_name(), "variable name")?;
self.skip_trivia_inline()?;
self.try_consume_exactly(";");
self.consume_new_line()?;
self.consume_indent_exactly(*indent)?;
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Open { typ, var, nxt: Box::new(nxt) };
Ok((stmt, nxt_indent))
}
fn parse_use(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
self.skip_trivia_inline()?;
let nam = self.parse_bend_name()?;
self.skip_trivia_inline()?;
self.consume_exactly("=")?;
self.skip_trivia_inline()?;
let bod = self.parse_expr(true, true)?;
self.skip_trivia_inline()?;
self.try_consume_exactly(";");
self.consume_new_line()?;
self.consume_indent_exactly(*indent)?;
let (nxt, nxt_indent) = self.parse_statement(indent)?;
let stmt = Stmt::Use { nam, val: Box::new(bod), nxt: Box::new(nxt) };
Ok((stmt, nxt_indent))
}
fn parse_local_def(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {