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Simplify some pattern matching

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This commit is contained in:
Richard Feldman 2020-08-25 23:25:26 -04:00
parent 658fd0a5f7
commit d9a96c9c66
1 changed files with 69 additions and 61 deletions
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130
compiler/parse/src/string_literal.rs
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@ -41,43 +41,47 @@ pub fn parse<'a>() -> impl Parser<'a, StringLiteral<'a>> {
parsed_chars += 1;
// Potentially end the string (unless this is an escaped `"`!)
if byte == b'"' && prev_byte != b'\\' {
let (string, state) = if parsed_chars == 2 {
match bytes.next() {
Some(byte) if *byte == b'"' => {
// If the first three chars were all `"`, then this
// literal begins with `"""` and is a block string.
return parse_block_string(arena, state, &mut bytes);
match byte {
b'"' if prev_byte != b'\\' => {
let (string, state) = if parsed_chars == 2 {
match bytes.next() {
Some(b'"') => {
// If the first three chars were all `"`, then this
// literal begins with `"""` and is a block string.
return parse_block_string(arena, state, &mut bytes);
}
_ => ("", state.advance_without_indenting(2)?),
}
_ => ("", state.advance_without_indenting(2)?),
}
} else {
// Start at 1 so we omit the opening `"`.
// Subtract 1 from parsed_chars so we omit the closing `"`.
let string_bytes = &state.bytes[1..(parsed_chars - 1)];
} else {
// Start at 1 so we omit the opening `"`.
// Subtract 1 from parsed_chars so we omit the closing `"`.
let string_bytes = &state.bytes[1..(parsed_chars - 1)];
match parse_utf8(string_bytes) {
Ok(string) => (string, state.advance_without_indenting(parsed_chars)?),
Err(reason) => {
return state.fail(reason);
match parse_utf8(string_bytes) {
Ok(string) => (string, state.advance_without_indenting(parsed_chars)?),
Err(reason) => {
return state.fail(reason);
}
}
}
};
};
return Ok((StringLiteral::Line(string), state));
} else if byte == b'\n' {
// This is a single-line string, which cannot have newlines!
// Treat this as an unclosed string literal, and consume
// all remaining chars. This will mask all other errors, but
// it should make it easiest to debug; the file will be a giant
// error starting from where the open quote appeared.
return Err(unexpected(
state.bytes.len() - 1,
state,
Attempting::StringLiteral,
));
} else {
prev_byte = byte;
return Ok((StringLiteral::Line(string), state));
}
b'\n' => {
// This is a single-line string, which cannot have newlines!
// Treat this as an unclosed string literal, and consume
// all remaining chars. This will mask all other errors, but
// it should make it easiest to debug; the file will be a giant
// error starting from where the open quote appeared.
return Err(unexpected(
state.bytes.len() - 1,
state,
Attempting::StringLiteral,
));
}
_ => {
prev_byte = byte;
}
}
}
@ -112,42 +116,46 @@ where
parsed_chars += 1;
// Potentially end the string (unless this is an escaped `"`!)
if *byte == b'"' && prev_byte != b'\\' {
if quotes_seen == 2 {
// three consecutive qoutes, end string
match byte {
b'"' if prev_byte != b'\\' => {
if quotes_seen == 2 {
// three consecutive qoutes, end string
// Subtract 3 from parsed_chars so we omit the closing `"`.
let line_bytes = &state.bytes[line_start..(parsed_chars - 3)];
// Subtract 3 from parsed_chars so we omit the closing `"`.
let line_bytes = &state.bytes[line_start..(parsed_chars - 3)];
return match parse_utf8(line_bytes) {
return match parse_utf8(line_bytes) {
Ok(line) => {
let state = state.advance_without_indenting(parsed_chars)?;
lines.push(line);
Ok((StringLiteral::Block(arena.alloc(lines)), state))
}
Err(reason) => state.fail(reason),
};
}
quotes_seen += 1;
}
b'\n' => {
// note this includes the newline
let line_bytes = &state.bytes[line_start..parsed_chars];
match parse_utf8(line_bytes) {
Ok(line) => {
let state = state.advance_without_indenting(parsed_chars)?;
lines.push(line);
Ok((StringLiteral::Block(arena.alloc(lines)), state))
quotes_seen = 0;
line_start = parsed_chars;
}
Err(reason) => {
return state.fail(reason);
}
Err(reason) => state.fail(reason),
};
}
quotes_seen += 1;
} else if *byte == b'\n' {
// note this includes the newline
let line_bytes = &state.bytes[line_start..parsed_chars];
match parse_utf8(line_bytes) {
Ok(line) => {
lines.push(line);
quotes_seen = 0;
line_start = parsed_chars;
}
Err(reason) => {
return state.fail(reason);
}
}
} else {
quotes_seen = 0;
_ => {
quotes_seen = 0;
}
}
prev_byte = *byte;