forked from extern/nushell
9e7f84afb0
In the final match of `lex_item`, we'll return `Err(ParseError)` in rare case, normally we'll return None. So I think making error part mutable can reduce some code, and it's better if we want to add more lex items.
492 lines
16 KiB
Rust
492 lines
16 KiB
Rust
use nu_protocol::{ParseError, Span};
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#[derive(Debug, PartialEq, Eq, Clone, Copy)]
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pub enum TokenContents {
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Item,
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Comment,
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Pipe,
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PipePipe,
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Semicolon,
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OutGreaterThan,
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ErrGreaterThan,
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OutErrGreaterThan,
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Eol,
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}
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#[derive(Debug, PartialEq, Eq)]
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pub struct Token {
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pub contents: TokenContents,
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pub span: Span,
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}
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impl Token {
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pub fn new(contents: TokenContents, span: Span) -> Token {
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Token { contents, span }
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}
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}
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#[derive(Clone, Copy, Debug)]
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pub enum BlockKind {
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Paren,
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CurlyBracket,
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SquareBracket,
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AngleBracket,
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}
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impl BlockKind {
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fn closing(self) -> u8 {
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match self {
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BlockKind::Paren => b')',
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BlockKind::SquareBracket => b']',
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BlockKind::CurlyBracket => b'}',
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BlockKind::AngleBracket => b'>',
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}
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}
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}
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// A baseline token is terminated if it's not nested inside of a paired
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// delimiter and the next character is one of: `|`, `;`, `#` or any
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// whitespace.
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fn is_item_terminator(
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block_level: &[BlockKind],
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c: u8,
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additional_whitespace: &[u8],
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special_tokens: &[u8],
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) -> bool {
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block_level.is_empty()
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&& (c == b' '
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|| c == b'\t'
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|| c == b'\n'
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|| c == b'\r'
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|| c == b'|'
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|| c == b';'
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|| additional_whitespace.contains(&c)
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|| special_tokens.contains(&c))
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}
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// A special token is one that is a byte that stands alone as its own token. For example
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// when parsing a signature you may want to have `:` be able to separate tokens and also
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// to be handled as its own token to notify you you're about to parse a type in the example
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// `foo:bar`
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fn is_special_item(block_level: &[BlockKind], c: u8, special_tokens: &[u8]) -> bool {
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block_level.is_empty() && special_tokens.contains(&c)
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}
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pub fn lex_item(
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input: &[u8],
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curr_offset: &mut usize,
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span_offset: usize,
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additional_whitespace: &[u8],
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special_tokens: &[u8],
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in_signature: bool,
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) -> (Token, Option<ParseError>) {
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// This variable tracks the starting character of a string literal, so that
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// we remain inside the string literal lexer mode until we encounter the
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// closing quote.
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let mut quote_start: Option<u8> = None;
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let mut in_comment = false;
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let token_start = *curr_offset;
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// This Vec tracks paired delimiters
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let mut block_level: Vec<BlockKind> = vec![];
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// The process of slurping up a baseline token repeats:
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//
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// - String literal, which begins with `'` or `"`, and continues until
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// the same character is encountered again.
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// - Delimiter pair, which begins with `[`, `(`, or `{`, and continues until
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// the matching closing delimiter is found, skipping comments and string
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// literals.
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// - When not nested inside of a delimiter pair, when a terminating
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// character (whitespace, `|`, `;` or `#`) is encountered, the baseline
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// token is done.
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// - Otherwise, accumulate the character into the current baseline token.
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while let Some(c) = input.get(*curr_offset) {
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let c = *c;
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if let Some(start) = quote_start {
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// Check if we're in an escape sequence
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if c == b'\\' && start == b'"' {
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// Go ahead and consume the escape character if possible
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if input.get(*curr_offset + 1).is_some() {
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// Successfully escaped the character
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*curr_offset += 2;
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continue;
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} else {
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let span = Span::new(span_offset + token_start, span_offset + *curr_offset);
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return (
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Token {
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contents: TokenContents::Item,
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span,
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},
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Some(ParseError::UnexpectedEof(
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(start as char).to_string(),
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Span::new(span.end, span.end),
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)),
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);
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}
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}
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// If we encountered the closing quote character for the current
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// string, we're done with the current string.
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if c == start {
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// Also need to check to make sure we aren't escaped
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quote_start = None;
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}
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} else if c == b'#' {
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if is_item_terminator(&block_level, c, additional_whitespace, special_tokens) {
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break;
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}
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in_comment = true;
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} else if c == b'\n' || c == b'\r' {
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in_comment = false;
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if is_item_terminator(&block_level, c, additional_whitespace, special_tokens) {
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break;
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}
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} else if in_comment {
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if is_item_terminator(&block_level, c, additional_whitespace, special_tokens) {
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break;
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}
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} else if is_special_item(&block_level, c, special_tokens) && token_start == *curr_offset {
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*curr_offset += 1;
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break;
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} else if c == b'\'' || c == b'"' || c == b'`' {
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// We encountered the opening quote of a string literal.
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quote_start = Some(c);
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} else if c == b'[' {
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// We encountered an opening `[` delimiter.
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block_level.push(BlockKind::SquareBracket);
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} else if c == b'<' && in_signature {
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block_level.push(BlockKind::AngleBracket);
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} else if c == b'>' && in_signature {
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if let Some(BlockKind::AngleBracket) = block_level.last() {
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let _ = block_level.pop();
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}
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} else if c == b']' {
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// We encountered a closing `]` delimiter. Pop off the opening `[`
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// delimiter.
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if let Some(BlockKind::SquareBracket) = block_level.last() {
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let _ = block_level.pop();
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}
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} else if c == b'{' {
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// We encountered an opening `{` delimiter.
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block_level.push(BlockKind::CurlyBracket);
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} else if c == b'}' {
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// We encountered a closing `}` delimiter. Pop off the opening `{`.
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if let Some(BlockKind::CurlyBracket) = block_level.last() {
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let _ = block_level.pop();
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} else {
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// We encountered a closing `}` delimiter, but the last opening
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// delimiter was not a `{`. This is an error.
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let span = Span::new(span_offset + token_start, span_offset + *curr_offset);
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*curr_offset += 1;
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return (
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Token {
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contents: TokenContents::Item,
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span,
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},
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Some(ParseError::Unbalanced(
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"{".to_string(),
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"}".to_string(),
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Span::new(span.end, span.end + 1),
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)),
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);
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}
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} else if c == b'(' {
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// We encountered an opening `(` delimiter.
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block_level.push(BlockKind::Paren);
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} else if c == b')' {
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// We encountered a closing `)` delimiter. Pop off the opening `(`.
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if let Some(BlockKind::Paren) = block_level.last() {
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let _ = block_level.pop();
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}
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} else if is_item_terminator(&block_level, c, additional_whitespace, special_tokens) {
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break;
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}
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*curr_offset += 1;
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}
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let span = Span::new(span_offset + token_start, span_offset + *curr_offset);
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// If there is still unclosed opening delimiters, remember they were missing
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if let Some(block) = block_level.last() {
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let delim = block.closing();
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let cause =
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ParseError::UnexpectedEof((delim as char).to_string(), Span::new(span.end, span.end));
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return (
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Token {
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contents: TokenContents::Item,
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span,
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},
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Some(cause),
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);
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}
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if let Some(delim) = quote_start {
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// The non-lite parse trims quotes on both sides, so we add the expected quote so that
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// anyone wanting to consume this partial parse (e.g., completions) will be able to get
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// correct information from the non-lite parse.
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return (
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Token {
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contents: TokenContents::Item,
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span,
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},
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Some(ParseError::UnexpectedEof(
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(delim as char).to_string(),
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Span::new(span.end, span.end),
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)),
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);
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}
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// If we didn't accumulate any characters, it's an unexpected error.
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if *curr_offset - token_start == 0 {
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return (
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Token {
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contents: TokenContents::Item,
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span,
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},
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Some(ParseError::UnexpectedEof("command".to_string(), span)),
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);
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}
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let mut err = None;
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let output = match &input[(span.start - span_offset)..(span.end - span_offset)] {
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b"out>" | b"o>" => Token {
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contents: TokenContents::OutGreaterThan,
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span,
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},
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b"err>" | b"e>" => Token {
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contents: TokenContents::ErrGreaterThan,
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span,
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},
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b"out+err>" | b"err+out>" | b"o+e>" | b"e+o>" => Token {
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contents: TokenContents::OutErrGreaterThan,
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span,
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},
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b"&&" => {
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err = Some(ParseError::ShellAndAnd(span));
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Token {
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contents: TokenContents::Item,
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span,
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}
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}
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b"2>" => {
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err = Some(ParseError::ShellErrRedirect(span));
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Token {
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contents: TokenContents::Item,
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span,
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}
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}
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b"2>&1" => {
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err = Some(ParseError::ShellOutErrRedirect(span));
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Token {
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contents: TokenContents::Item,
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span,
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}
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}
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_ => Token {
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contents: TokenContents::Item,
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span,
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},
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};
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(output, err)
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}
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pub fn lex_signature(
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input: &[u8],
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span_offset: usize,
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additional_whitespace: &[u8],
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special_tokens: &[u8],
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skip_comment: bool,
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) -> (Vec<Token>, Option<ParseError>) {
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lex_internal(
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input,
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span_offset,
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additional_whitespace,
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special_tokens,
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skip_comment,
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true,
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)
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}
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pub fn lex(
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input: &[u8],
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span_offset: usize,
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additional_whitespace: &[u8],
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special_tokens: &[u8],
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skip_comment: bool,
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) -> (Vec<Token>, Option<ParseError>) {
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lex_internal(
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input,
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span_offset,
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additional_whitespace,
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special_tokens,
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skip_comment,
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false,
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)
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}
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fn lex_internal(
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input: &[u8],
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span_offset: usize,
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additional_whitespace: &[u8],
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special_tokens: &[u8],
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skip_comment: bool,
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// within signatures we want to treat `<` and `>` specially
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in_signature: bool,
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) -> (Vec<Token>, Option<ParseError>) {
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let mut error = None;
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let mut curr_offset = 0;
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let mut output = vec![];
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let mut is_complete = true;
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while let Some(c) = input.get(curr_offset) {
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let c = *c;
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if c == b'|' {
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// If the next character is `|`, it's either `|` or `||`.
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let idx = curr_offset;
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let prev_idx = idx;
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curr_offset += 1;
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// If the next character is `|`, we're looking at a `||`.
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if let Some(c) = input.get(curr_offset) {
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if *c == b'|' {
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let idx = curr_offset;
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curr_offset += 1;
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output.push(Token::new(
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TokenContents::PipePipe,
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Span::new(span_offset + prev_idx, span_offset + idx + 1),
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));
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continue;
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}
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}
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// Otherwise, it's just a regular `|` token.
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// Before we push, check to see if the previous character was a newline.
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// If so, then this is a continuation of the previous line
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if let Some(prev) = output.last_mut() {
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match prev.contents {
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TokenContents::Eol => {
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*prev = Token::new(
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TokenContents::Pipe,
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Span::new(span_offset + idx, span_offset + idx + 1),
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);
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// And this is a continuation of the previous line if previous line is a
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// comment line (combined with EOL + Comment)
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//
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// Initially, the last one token is TokenContents::Pipe, we don't need to
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// check it, so the beginning offset is 2.
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let mut offset = 2;
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while output.len() > offset {
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let index = output.len() - offset;
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if output[index].contents == TokenContents::Comment
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&& output[index - 1].contents == TokenContents::Eol
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{
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output.remove(index - 1);
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offset += 1;
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} else {
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break;
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}
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}
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}
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_ => {
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output.push(Token::new(
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TokenContents::Pipe,
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Span::new(span_offset + idx, span_offset + idx + 1),
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));
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}
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}
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} else {
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output.push(Token::new(
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TokenContents::Pipe,
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Span::new(span_offset + idx, span_offset + idx + 1),
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));
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}
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is_complete = false;
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} else if c == b';' {
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// If the next character is a `;`, we're looking at a semicolon token.
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if !is_complete && error.is_none() {
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error = Some(ParseError::ExtraTokens(Span::new(
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curr_offset,
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curr_offset + 1,
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)));
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}
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let idx = curr_offset;
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curr_offset += 1;
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output.push(Token::new(
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TokenContents::Semicolon,
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Span::new(span_offset + idx, span_offset + idx + 1),
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));
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} else if c == b'\r' {
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// Ignore a stand-alone carriage return
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curr_offset += 1;
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} else if c == b'\n' {
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// If the next character is a newline, we're looking at an EOL (end of line) token.
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let idx = curr_offset;
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curr_offset += 1;
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if !additional_whitespace.contains(&c) {
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output.push(Token::new(
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TokenContents::Eol,
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Span::new(span_offset + idx, span_offset + idx + 1),
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));
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}
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} else if c == b'#' {
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// If the next character is `#`, we're at the beginning of a line
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// comment. The comment continues until the next newline.
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let mut start = curr_offset;
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while let Some(input) = input.get(curr_offset) {
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if *input == b'\n' {
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if !skip_comment {
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output.push(Token::new(
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TokenContents::Comment,
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Span::new(span_offset + start, span_offset + curr_offset),
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));
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}
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start = curr_offset;
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break;
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} else {
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curr_offset += 1;
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}
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}
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if start != curr_offset && !skip_comment {
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output.push(Token::new(
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TokenContents::Comment,
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Span::new(span_offset + start, span_offset + curr_offset),
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));
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}
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} else if c == b' ' || c == b'\t' || additional_whitespace.contains(&c) {
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// If the next character is non-newline whitespace, skip it.
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curr_offset += 1;
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} else {
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// Otherwise, try to consume an unclassified token.
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let (token, err) = lex_item(
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input,
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&mut curr_offset,
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span_offset,
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additional_whitespace,
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special_tokens,
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in_signature,
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);
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if error.is_none() {
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error = err;
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}
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is_complete = true;
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output.push(token);
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}
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}
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(output, error)
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}
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