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321 lines
14 KiB
Rust
321 lines
14 KiB
Rust
use crate::ast::{EscapedChar, StrLiteral, StrSegment};
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use crate::expr;
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use crate::parser::Progress::*;
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use crate::parser::{allocated, loc, specialize_ref, word1, BadInputError, EString, Parser, 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, state: State<'a>| {
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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((
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NoProgress,
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EString::CodePtEnd(state.line, state.column),
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state,
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));
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} else {
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let state = state.advance_without_indenting_ee(buf.len(), |r, c| {
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EString::Space(BadInputError::LineTooLong, r, c)
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})?;
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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((
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NoProgress,
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EString::CodePtEnd(state.line, state.column),
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state,
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))
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}
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}
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macro_rules! advance_state {
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($state:expr, $n:expr) => {
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$state.advance_without_indenting_ee($n, |r, c| {
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EString::Space(BadInputError::LineTooLong, r, c)
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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>| {
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let is_multiline;
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let mut bytes;
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if state.bytes.starts_with(b"\"\"\"") {
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// we will be parsing a multi-string
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is_multiline = true;
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bytes = state.bytes[3..].iter();
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state = advance_state!(state, 3)?;
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} else if state.bytes.starts_with(b"\"") {
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// we will be parsing a single-string
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is_multiline = false;
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bytes = state.bytes[1..].iter();
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state = advance_state!(state, 1)?;
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} else {
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return Err((NoProgress, EString::Open(state.line, state.column), state));
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}
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// At the parsing stage we keep the entire raw string, because the formatter
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// needs the raw string. (For example, so it can "remember" whether you
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// wrote \u{...} or the actual unicode character itself.)
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//
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// Since we're keeping the entire raw string, all we need to track is
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// how many characters we've parsed. So far, that's 1 (the opening `"`).
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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($ch));
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// Advance past the segment we just added
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state = advance_state!(state, segment_parsed_bytes)?;
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// Reset the segment
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segment_parsed_bytes = 0;
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};
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}
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macro_rules! end_segment {
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($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_state!(state, 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.line, state.column),
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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(&[]), advance_state!(state, 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(""), advance_state!(state, 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, advance_state!(state, 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, advance_state!(state, 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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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(state.line, state.column),
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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_state!(state, 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(EString::Format, loc(allocated(expr::expr_help(0)))),
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word1(b')', EString::FormatEnd)
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)
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.parse(arena, state)?;
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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_state!(state, 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)?;
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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((
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MadeProgress,
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EString::UnknownEscape(state.line, state.column),
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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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_ => {
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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(state.line, state.column)
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} else {
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EString::EndlessSingle(state.line, state.column)
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},
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state,
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))
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}
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}
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