nushell/crates/nu-parser/src/lite_parser.rs
Horasal b943cbedff
skip comments and eols while parsing pipeline (#10149)
This pr 
- fixes https://github.com/nushell/nushell/issues/10143
- fixes https://github.com/nushell/nushell/issues/5559

# Description

Current `lite_parse` does not handle multiple line comments and eols in
pipeline.
When parsing the following tokens:


| `"abcdefg"` | ` \|` | `# foobar` | ` \n` | `split chars` |
| ------------- | ------------- |------------- |-------------
|------------- |
| [Command] | [Pipe] | [Comment] | [Eol] | [Command] |
| | | Last Token |Current Token | |

`TokenContent::Eol` handler only checks if `last_token` is `Pipe` but it
will be broken if there exist any other thing, e.g. extra `[Comment]` in
this example.

This pr make the following change:

- While parsing `[Eol]`, try to find the last non-comment token as
`last_token`
- Comment is supposed as `[Comment]+` or `([Comment] [Eol])+`
- `[Eol]+` is still parsed just like current nu (i.e. generates
`nothing`).

Notice that this pr is just a quick patch if more comment/eol related
issue occures, `lite_parser` may need a rewrite.

# User-Facing Changes

Now the following pipeline works: 

```bash
1 | # comment
each { |it| $it + 2 } | # comment
math sum
```

Comment will not end the pipeline in interactive mode:

```bash
❯ 1 | # comment   (now enter multiple line mode instead of end)
▶▶ # foo
▶▶ 2
```

# Tests + Formatting

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting

None

---------

Co-authored-by: Horasal <horsal@horsal.dev>
2023-08-30 13:24:13 -05:00

486 lines
18 KiB
Rust

/// Lite parsing converts a flat stream of tokens from the lexer to a syntax element structure that
/// can be parsed.
use crate::{Token, TokenContents};
use nu_protocol::{ast::Redirection, ParseError, Span};
#[derive(Debug)]
pub struct LiteCommand {
pub comments: Vec<Span>,
pub parts: Vec<Span>,
}
impl Default for LiteCommand {
fn default() -> Self {
Self::new()
}
}
impl LiteCommand {
pub fn new() -> Self {
Self {
comments: vec![],
parts: vec![],
}
}
pub fn push(&mut self, span: Span) {
self.parts.push(span);
}
pub fn is_empty(&self) -> bool {
self.parts.is_empty()
}
}
// Note: the Span is the span of the connector not the whole element
#[derive(Debug)]
pub enum LiteElement {
Command(Option<Span>, LiteCommand),
Redirection(Span, Redirection, LiteCommand),
// SeparateRedirection variant can only be generated by two different Redirection variant
SeparateRedirection {
out: (Span, LiteCommand),
err: (Span, LiteCommand),
},
// SameTargetRedirection variant can only be generated by Command with Redirection::OutAndErr
SameTargetRedirection {
cmd: (Option<Span>, LiteCommand),
redirection: (Span, LiteCommand),
},
}
#[derive(Debug, Default)]
pub struct LitePipeline {
pub commands: Vec<LiteElement>,
}
impl LitePipeline {
pub fn new() -> Self {
Self { commands: vec![] }
}
pub fn push(&mut self, element: LiteElement) {
self.commands.push(element);
}
pub fn insert(&mut self, index: usize, element: LiteElement) {
self.commands.insert(index, element);
}
pub fn is_empty(&self) -> bool {
self.commands.is_empty()
}
}
#[derive(Debug)]
pub struct LiteBlock {
pub block: Vec<LitePipeline>,
}
impl Default for LiteBlock {
fn default() -> Self {
Self::new()
}
}
impl LiteBlock {
pub fn new() -> Self {
Self { block: vec![] }
}
pub fn push(&mut self, mut pipeline: LitePipeline) {
// once we push `pipeline` to our block
// the block takes ownership of `pipeline`, which means that
// our `pipeline` is complete on collecting commands.
self.merge_redirections(&mut pipeline);
self.merge_cmd_with_outerr_redirection(&mut pipeline);
self.block.push(pipeline);
}
pub fn is_empty(&self) -> bool {
self.block.is_empty()
}
fn merge_cmd_with_outerr_redirection(&self, pipeline: &mut LitePipeline) {
let mut cmd_index = None;
let mut outerr_index = None;
for (index, cmd) in pipeline.commands.iter().enumerate() {
if let LiteElement::Command(..) = cmd {
cmd_index = Some(index);
}
if let LiteElement::Redirection(_span, Redirection::StdoutAndStderr, _target_cmd) = cmd
{
outerr_index = Some(index);
break;
}
}
if let (Some(cmd_index), Some(outerr_index)) = (cmd_index, outerr_index) {
// we can make sure that cmd_index is less than outerr_index.
let outerr_redirect = pipeline.commands.remove(outerr_index);
let cmd = pipeline.commands.remove(cmd_index);
// `outerr_redirect` and `cmd` should always be `LiteElement::Command` and `LiteElement::Redirection`
if let (
LiteElement::Command(cmd_span, lite_cmd),
LiteElement::Redirection(span, _, outerr_cmd),
) = (cmd, outerr_redirect)
{
pipeline.insert(
cmd_index,
LiteElement::SameTargetRedirection {
cmd: (cmd_span, lite_cmd),
redirection: (span, outerr_cmd),
},
)
}
}
}
fn merge_redirections(&self, pipeline: &mut LitePipeline) {
// In case our command may contains both stdout and stderr redirection.
// We pick them out and Combine them into one LiteElement::SeparateRedirection variant.
let mut stdout_index = None;
let mut stderr_index = None;
for (index, cmd) in pipeline.commands.iter().enumerate() {
if let LiteElement::Redirection(_span, redirection, _target_cmd) = cmd {
match *redirection {
Redirection::Stderr => stderr_index = Some(index),
Redirection::Stdout => stdout_index = Some(index),
Redirection::StdoutAndStderr => {}
}
}
}
if let (Some(out_indx), Some(err_indx)) = (stdout_index, stderr_index) {
let (out_redirect, err_redirect, new_indx) = {
// to avoid panic, we need to remove commands which have larger index first.
if out_indx > err_indx {
let out_redirect = pipeline.commands.remove(out_indx);
let err_redirect = pipeline.commands.remove(err_indx);
(out_redirect, err_redirect, err_indx)
} else {
let err_redirect = pipeline.commands.remove(err_indx);
let out_redirect = pipeline.commands.remove(out_indx);
(out_redirect, err_redirect, out_indx)
}
};
// `out_redirect` and `err_redirect` should always be `LiteElement::Redirection`
if let (
LiteElement::Redirection(out_span, _, out_command),
LiteElement::Redirection(err_span, _, err_command),
) = (out_redirect, err_redirect)
{
// using insert with specific index to keep original
// pipeline commands order.
pipeline.insert(
new_indx,
LiteElement::SeparateRedirection {
out: (out_span, out_command),
err: (err_span, err_command),
},
)
}
}
}
}
fn last_non_comment_token(tokens: &[Token], cur_idx: usize) -> Option<TokenContents> {
let mut expect = TokenContents::Comment;
for token in tokens.iter().take(cur_idx).rev() {
// skip ([Comment]+ [Eol]) pair
match (token.contents, expect) {
(TokenContents::Comment, TokenContents::Comment)
| (TokenContents::Comment, TokenContents::Eol) => expect = TokenContents::Eol,
(TokenContents::Eol, TokenContents::Eol) => expect = TokenContents::Comment,
(token, _) => return Some(token),
}
}
None
}
pub fn lite_parse(tokens: &[Token]) -> (LiteBlock, Option<ParseError>) {
let mut block = LiteBlock::new();
let mut curr_pipeline = LitePipeline::new();
let mut curr_command = LiteCommand::new();
let mut last_token = TokenContents::Eol;
let mut last_connector = TokenContents::Pipe;
let mut last_connector_span: Option<Span> = None;
if tokens.is_empty() {
return (LiteBlock::new(), None);
}
let mut curr_comment: Option<Vec<Span>> = None;
let mut error = None;
for (idx, token) in tokens.iter().enumerate() {
match &token.contents {
TokenContents::PipePipe => {
error = error.or(Some(ParseError::ShellOrOr(token.span)));
curr_command.push(token.span);
last_token = TokenContents::Item;
}
TokenContents::Item => {
// If we have a comment, go ahead and attach it
if let Some(curr_comment) = curr_comment.take() {
curr_command.comments = curr_comment;
}
curr_command.push(token.span);
last_token = TokenContents::Item;
}
TokenContents::OutGreaterThan
| TokenContents::ErrGreaterThan
| TokenContents::OutErrGreaterThan => {
if !curr_command.is_empty() {
match last_connector {
TokenContents::OutGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::Stdout,
curr_command,
));
}
TokenContents::ErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::Stderr,
curr_command,
));
}
TokenContents::OutErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::StdoutAndStderr,
curr_command,
));
}
_ => {
curr_pipeline
.push(LiteElement::Command(last_connector_span, curr_command));
}
}
curr_command = LiteCommand::new();
}
last_token = token.contents;
last_connector = token.contents;
last_connector_span = Some(token.span);
}
TokenContents::Pipe => {
if !curr_command.is_empty() {
match last_connector {
TokenContents::OutGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
token.span,
Redirection::Stdout,
curr_command,
));
}
TokenContents::ErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
token.span,
Redirection::Stderr,
curr_command,
));
}
TokenContents::OutErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
token.span,
Redirection::StdoutAndStderr,
curr_command,
));
}
_ => {
curr_pipeline
.push(LiteElement::Command(last_connector_span, curr_command));
}
}
curr_command = LiteCommand::new();
}
last_token = TokenContents::Pipe;
last_connector = TokenContents::Pipe;
last_connector_span = Some(token.span);
}
TokenContents::Eol => {
// Handle `[Command] [Pipe] ([Comment] | [Eol])+ [Command]`
//
// `[Eol]` branch checks if previous token is `[Pipe]` to construct pipeline
// and so `[Comment] | [Eol]` should be ignore to make it work
let actual_token = last_non_comment_token(tokens, idx);
if actual_token != Some(TokenContents::Pipe)
&& actual_token != Some(TokenContents::OutGreaterThan)
{
if !curr_command.is_empty() {
match last_connector {
TokenContents::OutGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span.expect(
"internal error: redirection missing span information",
),
Redirection::Stdout,
curr_command,
));
}
TokenContents::ErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span.expect(
"internal error: redirection missing span information",
),
Redirection::Stderr,
curr_command,
));
}
TokenContents::OutErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span.expect(
"internal error: redirection missing span information",
),
Redirection::StdoutAndStderr,
curr_command,
));
}
_ => {
curr_pipeline
.push(LiteElement::Command(last_connector_span, curr_command));
}
}
curr_command = LiteCommand::new();
}
if !curr_pipeline.is_empty() {
block.push(curr_pipeline);
curr_pipeline = LitePipeline::new();
last_connector = TokenContents::Pipe;
last_connector_span = None;
}
}
if last_token == TokenContents::Eol {
// Clear out the comment as we're entering a new comment
curr_comment = None;
}
last_token = TokenContents::Eol;
}
TokenContents::Semicolon => {
if !curr_command.is_empty() {
match last_connector {
TokenContents::OutGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::Stdout,
curr_command,
));
}
TokenContents::ErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::Stderr,
curr_command,
));
}
TokenContents::OutErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::StdoutAndStderr,
curr_command,
));
}
_ => {
curr_pipeline
.push(LiteElement::Command(last_connector_span, curr_command));
}
}
curr_command = LiteCommand::new();
}
if !curr_pipeline.is_empty() {
block.push(curr_pipeline);
curr_pipeline = LitePipeline::new();
last_connector = TokenContents::Pipe;
last_connector_span = None;
}
last_token = TokenContents::Semicolon;
}
TokenContents::Comment => {
// Comment is beside something
if last_token != TokenContents::Eol {
curr_command.comments.push(token.span);
curr_comment = None;
} else {
// Comment precedes something
if let Some(curr_comment) = &mut curr_comment {
curr_comment.push(token.span);
} else {
curr_comment = Some(vec![token.span]);
}
}
last_token = TokenContents::Comment;
}
}
}
if !curr_command.is_empty() {
match last_connector {
TokenContents::OutGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::Stdout,
curr_command,
));
}
TokenContents::ErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::Stderr,
curr_command,
));
}
TokenContents::OutErrGreaterThan => {
curr_pipeline.push(LiteElement::Redirection(
last_connector_span
.expect("internal error: redirection missing span information"),
Redirection::StdoutAndStderr,
curr_command,
));
}
_ => {
curr_pipeline.push(LiteElement::Command(last_connector_span, curr_command));
}
}
}
if !curr_pipeline.is_empty() {
block.push(curr_pipeline);
}
if last_non_comment_token(tokens, tokens.len()) == Some(TokenContents::Pipe) {
(
block,
Some(ParseError::UnexpectedEof(
"pipeline missing end".into(),
tokens[tokens.len() - 1].span,
)),
)
} else {
(block, error)
}
}