mirror of
https://github.com/roc-lang/roc.git
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07be8ec000
This removes the need to explicitly pass thru min_indent when using the parser combinators. My ultimate goal here is to evolve the current parser closer toward a purely combinator-based parser, at which point we can more easily transition smoothly to a formal(ish) grammar, or expand the meanings of combinators to include things like: * Incremental (re)parsing * Unified parsing and formatting code * Better error recovery * Using the main parser directly for syntax highlighting
459 lines
19 KiB
Rust
459 lines
19 KiB
Rust
use crate::ast::{EscapedChar, StrLiteral, StrSegment};
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use crate::expr;
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use crate::parser::Progress::{self, *};
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use crate::parser::{
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allocated, loc, reset_min_indent, specialize_ref, word1, BadInputError, EString, Parser,
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};
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use crate::state::State;
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use bumpalo::collections::vec::Vec;
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use bumpalo::Bump;
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/// One or more ASCII hex digits. (Useful when parsing unicode escape codes,
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/// which must consist entirely of ASCII hex digits.)
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fn ascii_hex_digits<'a>() -> impl Parser<'a, &'a str, EString<'a>> {
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move |arena, mut state: State<'a>, _min_indent: u32| {
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let mut buf = bumpalo::collections::String::new_in(arena);
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for &byte in state.bytes().iter() {
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if (byte as char).is_ascii_hexdigit() {
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buf.push(byte as char);
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} else if buf.is_empty() {
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// We didn't find any hex digits!
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return Err((NoProgress, EString::CodePtEnd(state.pos()), state));
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} else {
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state.advance_mut(buf.len());
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return Ok((MadeProgress, buf.into_bump_str(), state));
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}
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}
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Err((NoProgress, EString::CodePtEnd(state.pos()), state))
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}
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}
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pub fn parse_single_quote<'a>() -> impl Parser<'a, &'a str, EString<'a>> {
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move |arena: &'a Bump, mut state: State<'a>, _min_indent: u32| {
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if state.consume_mut("\'") {
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// we will be parsing a single-quote-string
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} else {
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return Err((NoProgress, EString::Open(state.pos()), state));
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}
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// Handle back slaches in byte literal
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// - starts with a backslash and used as an escape character. ex: '\n', '\t'
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// - single quote floating (un closed single quote) should be an error
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match state.bytes().first() {
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Some(b'\\') => {
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state.advance_mut(1);
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match state.bytes().first() {
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Some(&ch) => {
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state.advance_mut(1);
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if (ch == b'n' || ch == b'r' || ch == b't' || ch == b'\'' || ch == b'\\')
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&& (state.bytes().first() == Some(&b'\''))
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{
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state.advance_mut(1);
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let test = match ch {
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b'n' => '\n',
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b't' => '\t',
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b'r' => '\r',
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// since we checked the current char between the single quotes we
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// know they are valid UTF-8, allowing us to use 'from_u32_unchecked'
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_ => unsafe { char::from_u32_unchecked(ch as u32) },
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};
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return Ok((MadeProgress, &*arena.alloc_str(&test.to_string()), state));
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}
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// invalid error, backslah escaping something we do not recognize
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return Err((NoProgress, EString::CodePtEnd(state.pos()), state));
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}
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None => {
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// no close quote found
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return Err((NoProgress, EString::CodePtEnd(state.pos()), state));
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}
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}
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}
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Some(_) => {
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// do nothing for other characters, handled below
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}
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None => return Err((NoProgress, EString::CodePtEnd(state.pos()), state)),
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}
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let mut bytes = state.bytes().iter();
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let mut end_index = 1;
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// Copy paste problem in mono
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loop {
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match bytes.next() {
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Some(b'\'') => {
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break;
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}
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Some(_) => end_index += 1,
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None => {
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return Err((NoProgress, EString::Open(state.pos()), state));
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}
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}
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}
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if end_index == 1 {
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// no progress was made
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// this case is a double single quote, ex: ''
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// not supporting empty single quotes
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return Err((NoProgress, EString::Open(state.pos()), state));
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}
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if end_index > (std::mem::size_of::<u32>() + 1) {
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// bad case: too big to fit into u32
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return Err((NoProgress, EString::Open(state.pos()), state));
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}
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// happy case -> we have some bytes that will fit into a u32
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// ending up w/ a slice of bytes that we want to convert into an integer
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let raw_bytes = &state.bytes()[0..end_index - 1];
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state.advance_mut(end_index);
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match std::str::from_utf8(raw_bytes) {
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Ok(string) => Ok((MadeProgress, string, state)),
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Err(_) => {
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// invalid UTF-8
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return Err((NoProgress, EString::CodePtEnd(state.pos()), state));
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}
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}
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}
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}
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fn consume_indent<'a>(
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mut state: State<'a>,
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mut indent: u32,
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) -> Result<State, (Progress, EString<'a>, State<'a>)> {
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while indent > 0 {
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match state.bytes().first() {
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Some(b' ') => {
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state.advance_mut(1);
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indent -= 1;
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}
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None | Some(b'\n') => {
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break;
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}
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Some(_) => {
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return Err((
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MadeProgress,
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EString::MultilineInsufficientIndent(state.pos()),
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state,
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));
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}
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}
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}
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Ok(state)
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}
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fn utf8<'a>(
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state: State<'a>,
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string_bytes: &'a [u8],
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) -> Result<&'a str, (Progress, EString<'a>, State<'a>)> {
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std::str::from_utf8(string_bytes).map_err(|_| {
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// Note Based on where this `utf8` function is used, the fact that we know the whole string
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// in the parser is valid utf8, and barring bugs in the parser itself
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// (e.g. where we accidentally split a multibyte utf8 char), this error _should_ actually be unreachable.
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(
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MadeProgress,
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EString::Space(BadInputError::BadUtf8, state.pos()),
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state,
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)
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})
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}
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pub fn parse<'a>() -> impl Parser<'a, StrLiteral<'a>, EString<'a>> {
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use StrLiteral::*;
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move |arena: &'a Bump, mut state: State<'a>, min_indent: u32| {
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let is_multiline;
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let indent = state.column();
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let start_state;
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if state.consume_mut("\"\"\"") {
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start_state = state.clone();
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// we will be parsing a multi-line string
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is_multiline = true;
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if state.consume_mut("\n") {
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state = consume_indent(state, indent)?;
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}
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} else if state.consume_mut("\"") {
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start_state = state.clone();
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// we will be parsing a single-line string
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is_multiline = false;
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} else {
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return Err((NoProgress, EString::Open(state.pos()), state));
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}
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let mut bytes = state.bytes().iter();
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let mut segment_parsed_bytes = 0;
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let mut segments = Vec::new_in(arena);
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macro_rules! escaped_char {
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($ch:expr) => {
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// Record the escaped char.
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segments.push(StrSegment::EscapedChar($ch));
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// Advance past the segment we just added
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state.advance_mut(segment_parsed_bytes);
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// Reset the segment
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segment_parsed_bytes = 0;
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};
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}
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macro_rules! end_segment {
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($transform:expr) => {
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// Don't push anything if the string would be empty.
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if segment_parsed_bytes > 1 {
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// This function is always called after we just parsed
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// something which signalled that we should end the
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// current segment - so use segment_parsed_bytes - 1 here,
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// to exclude that char we just parsed.
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let string_bytes = &state.bytes()[0..(segment_parsed_bytes - 1)];
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match std::str::from_utf8(string_bytes) {
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Ok(string) => {
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state.advance_mut(string.len());
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segments.push($transform(string));
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}
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Err(_) => {
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return Err((
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MadeProgress,
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EString::Space(BadInputError::BadUtf8, state.pos()),
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state,
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));
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}
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}
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}
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// Depending on where this macro is used, in some
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// places this is unused.
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#[allow(unused_assignments)]
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{
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// This function is always called after we just parsed
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// something which signalled that we should end the
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// current segment.
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segment_parsed_bytes = 1;
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}
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};
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}
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while let Some(&byte) = bytes.next() {
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// This is for the byte we just grabbed from the iterator.
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segment_parsed_bytes += 1;
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match byte {
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b'"' => {
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if segment_parsed_bytes == 1 && segments.is_empty() {
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// special case of the empty string
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if is_multiline {
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if bytes.as_slice().starts_with(b"\"\"") {
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return Ok((MadeProgress, Block(&[]), state.advance(3)));
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} else {
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// this quote is in a block string
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continue;
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}
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} else {
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// This is the end of the string!
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// Advance 1 for the close quote
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return Ok((MadeProgress, PlainLine(""), state.advance(1)));
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}
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} else {
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// the string is non-empty, which means we need to convert any previous segments
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// and the current segment into a string literal
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if is_multiline {
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if bytes.as_slice().starts_with(b"\"\"") {
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end_segment!(StrSegment::Plaintext);
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let expr = if segments.len() == 1 {
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// We had exactly one segment, so this is a candidate
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// to be StrLiteral::Plaintext
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match segments.pop().unwrap() {
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StrSegment::Plaintext(string) => {
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StrLiteral::PlainLine(string)
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}
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other => StrLiteral::Line(arena.alloc([other])),
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}
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} else {
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Block(arena.alloc([segments.into_bump_slice()]))
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};
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return Ok((MadeProgress, expr, state.advance(3)));
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} else {
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// this quote is in a block string
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continue;
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}
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} else {
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end_segment!(StrSegment::Plaintext);
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let expr = if segments.len() == 1 {
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// We had exactly one segment, so this is a candidate
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// to be StrLiteral::Plaintext
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match segments.pop().unwrap() {
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StrSegment::Plaintext(string) => StrLiteral::PlainLine(string),
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other => StrLiteral::Line(arena.alloc([other])),
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}
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} else {
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Line(segments.into_bump_slice())
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};
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// Advance the state 1 to account for the closing `"`
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return Ok((MadeProgress, expr, state.advance(1)));
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}
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};
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}
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b'\n' => {
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if is_multiline {
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let without_newline = &state.bytes()[0..(segment_parsed_bytes - 1)];
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let with_newline = &state.bytes()[0..segment_parsed_bytes];
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state.advance_mut(segment_parsed_bytes);
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state = consume_indent(state, indent)?;
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bytes = state.bytes().iter();
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if state.bytes().starts_with(b"\"\"\"") {
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// ending the string; don't use the last newline
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segments
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.push(StrSegment::Plaintext(utf8(state.clone(), without_newline)?));
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} else {
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segments
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.push(StrSegment::Plaintext(utf8(state.clone(), with_newline)?));
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}
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segment_parsed_bytes = 0;
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continue;
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} else {
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// This is a single-line string, which cannot have newlines!
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// Treat this as an unclosed string literal, and consume
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// all remaining chars. This will mask all other errors, but
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// it should make it easiest to debug; the file will be a giant
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// error starting from where the open quote appeared.
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return Err((
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MadeProgress,
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EString::EndlessSingle(start_state.pos()),
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start_state,
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));
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}
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}
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b'\\' => {
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// We're about to begin an escaped segment of some sort!
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//
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// Record the current segment so we can begin a new one.
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// End it right before the `\` char we just parsed.
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end_segment!(StrSegment::Plaintext);
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// This is for the byte we're about to parse.
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segment_parsed_bytes += 1;
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// This is the start of a new escape. Look at the next byte
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// to figure out what type of escape it is.
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match bytes.next() {
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Some(b'(') => {
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// Advance past the `\(` before using the expr parser
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state.advance_mut(2);
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let original_byte_count = state.bytes().len();
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// This is an interpolated variable.
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// Parse an arbitrary expression, then give a
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// canonicalization error if that expression variant
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// is not allowed inside a string interpolation.
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let (_progress, loc_expr, new_state) = skip_second!(
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specialize_ref(
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EString::Format,
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loc(allocated(reset_min_indent(expr::expr_help())))
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),
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word1(b')', EString::FormatEnd)
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)
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.parse(arena, state, min_indent)?;
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// Advance the iterator past the expr we just parsed.
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for _ in 0..(original_byte_count - new_state.bytes().len()) {
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bytes.next();
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}
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segments.push(StrSegment::Interpolated(loc_expr));
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// Reset the segment
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segment_parsed_bytes = 0;
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state = new_state;
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}
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Some(b'u') => {
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// Advance past the `\u` before using the expr parser
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state.advance_mut(2);
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let original_byte_count = state.bytes().len();
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// Parse the hex digits, surrounded by parens, then
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// give a canonicalization error if the digits form
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// an invalid unicode code point.
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let (_progress, loc_digits, new_state) = between!(
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word1(b'(', EString::CodePtOpen),
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loc(ascii_hex_digits()),
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word1(b')', EString::CodePtEnd)
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)
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.parse(arena, state, min_indent)?;
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// Advance the iterator past the expr we just parsed.
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for _ in 0..(original_byte_count - new_state.bytes().len()) {
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bytes.next();
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}
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segments.push(StrSegment::Unicode(loc_digits));
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// Reset the segment
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segment_parsed_bytes = 0;
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state = new_state;
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}
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Some(b'\\') => {
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escaped_char!(EscapedChar::Backslash);
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}
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Some(b'"') => {
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escaped_char!(EscapedChar::Quote);
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}
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Some(b'r') => {
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escaped_char!(EscapedChar::CarriageReturn);
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}
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Some(b't') => {
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escaped_char!(EscapedChar::Tab);
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}
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Some(b'n') => {
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escaped_char!(EscapedChar::Newline);
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}
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_ => {
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// Invalid escape! A backslash must be followed
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// by either an open paren or else one of the
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// escapable characters (\n, \t, \", \\, etc)
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return Err((MadeProgress, EString::UnknownEscape(state.pos()), state));
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}
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}
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}
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_ => {
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// All other characters need no special handling.
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}
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}
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}
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// We ran out of characters before finding a closed quote
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Err((
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MadeProgress,
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if is_multiline {
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EString::EndlessMulti(start_state.pos())
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} else {
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EString::EndlessSingle(start_state.pos())
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},
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start_state,
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))
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}
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}
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