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Start grouping parsing of values better (#8470)

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# Description

This starts working on refactoring the parser to no longer use
SyntaxShape when making parsing decisions about values. This PR covers
grouping a few of the steps in `parse_value` to key off the first
character for what group of parsing steps it should use.

# User-Facing Changes

Hopefully none.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
This commit is contained in:
JT 2023-03-16 16:06:43 +13:00 committed by GitHub
parent aa876ce24f
commit b0ce602e4b
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 71 additions and 84 deletions
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155
crates/nu-parser/src/parser.rs
View File

@ -1695,6 +1695,75 @@ pub(crate) fn parse_dollar_expr(
}
}
pub fn parse_paren_expr(
working_set: &mut StateWorkingSet,
span: Span,
expand_aliases_denylist: &[usize],
) -> (Expression, Option<ParseError>) {
if let (expr, None) = parse_range(working_set, span, expand_aliases_denylist) {
(expr, None)
} else {
parse_full_cell_path(working_set, None, span, expand_aliases_denylist)
}
}
pub fn parse_brace_expr(
working_set: &mut StateWorkingSet,
span: Span,
shape: &SyntaxShape,
expand_aliases_denylist: &[usize],
) -> (Expression, Option<ParseError>) {
// Try to detect what kind of value we're about to parse
// FIXME: In the future, we should work over the token stream so we only have to do this once
// before parsing begins
// FIXME: we're still using the shape because we rely on it to know how to handle syntax where
// the parse is ambiguous. We'll need to update the parts of the grammar where this is ambiguous
// and then revisit the parsing.
let bytes = working_set.get_span_contents(Span::new(span.start + 1, span.end - 1));
let (tokens, _) = lex(bytes, span.start + 1, &[b'\r', b'\n', b'\t'], &[b':'], true);
let second_token = tokens
.get(0)
.map(|token| working_set.get_span_contents(token.span));
let second_token_contents = tokens.get(0).map(|token| token.contents);
let third_token = tokens
.get(1)
.map(|token| working_set.get_span_contents(token.span));
if matches!(second_token, None) {
// If we're empty, that means an empty record or closure
if matches!(shape, SyntaxShape::Closure(_)) {
parse_closure_expression(working_set, shape, span, expand_aliases_denylist)
} else if matches!(shape, SyntaxShape::Block) {
parse_block_expression(working_set, span, expand_aliases_denylist)
} else {
parse_record(working_set, span, expand_aliases_denylist)
}
} else if matches!(second_token_contents, Some(TokenContents::Pipe))
|| matches!(second_token_contents, Some(TokenContents::PipePipe))
{
parse_closure_expression(working_set, shape, span, expand_aliases_denylist)
} else if matches!(third_token, Some(b":")) {
parse_full_cell_path(working_set, None, span, expand_aliases_denylist)
} else if matches!(shape, SyntaxShape::Closure(_)) || matches!(shape, SyntaxShape::Any) {
parse_closure_expression(working_set, shape, span, expand_aliases_denylist)
} else if matches!(shape, SyntaxShape::Block) {
parse_block_expression(working_set, span, expand_aliases_denylist)
} else {
(
Expression::garbage(span),
Some(ParseError::Expected(
format!("non-block value: {shape}"),
span,
)),
)
}
}
pub fn parse_string_interpolation(
working_set: &mut StateWorkingSet,
span: Span,
@ -4135,7 +4204,6 @@ pub fn parse_table_expression(
pub fn parse_block_expression(
working_set: &mut StateWorkingSet,
shape: &SyntaxShape,
span: Span,
expand_aliases_denylist: &[usize],
) -> (Expression, Option<ParseError>) {
@ -4187,39 +4255,6 @@ pub fn parse_block_expression(
_ => (None, 0),
};
// TODO: Finish this
if let SyntaxShape::Closure(Some(v)) = shape {
if let Some((sig, sig_span)) = &signature {
if sig.num_positionals() > v.len() {
error = error.or_else(|| {
Some(ParseError::Expected(
format!(
"{} block parameter{}",
v.len(),
if v.len() > 1 { "s" } else { "" }
),
*sig_span,
))
});
}
for (expected, PositionalArg { name, shape, .. }) in
v.iter().zip(sig.required_positional.iter())
{
if expected != shape && *shape != SyntaxShape::Any {
error = error.or_else(|| {
Some(ParseError::ParameterMismatchType(
name.to_owned(),
expected.to_string(),
shape.to_string(),
*sig_span,
))
});
}
}
}
}
let (mut output, err) = parse_block(
working_set,
&output[amt_to_skip..],
@ -4437,18 +4472,6 @@ pub fn parse_value(
return (garbage(span), Some(ParseError::IncompleteParser(span)));
}
// First, check the special-cases. These will likely represent specific values as expressions
// and may fit a variety of shapes.
//
// We check variable first because immediately following we check for variables with cell paths
// which might result in a value that fits other shapes (and require the variable to already be
// declared)
if shape == &SyntaxShape::Variable {
trace!("parsing: variable");
return parse_variable_expr(working_set, span);
}
// Check for reserved keyword values
match bytes {
b"true" => {
@ -4504,44 +4527,8 @@ pub fn parse_value(
match bytes[0] {
b'$' => return parse_dollar_expr(working_set, span, expand_aliases_denylist),
b'(' => {
if let (expr, None) = parse_range(working_set, span, expand_aliases_denylist) {
return (expr, None);
} else if matches!(shape, SyntaxShape::Signature) {
return parse_signature(working_set, span, expand_aliases_denylist);
} else {
return parse_full_cell_path(working_set, None, span, expand_aliases_denylist);
}
}
b'{' => {
if !matches!(shape, SyntaxShape::Closure(..)) && !matches!(shape, SyntaxShape::Block) {
let (expr, err) =
parse_full_cell_path(working_set, None, span, expand_aliases_denylist);
match err {
Some(err) => {
if let ParseError::Unbalanced(_, _, _) = err {
return (expr, Some(err));
}
}
None => return (expr, None),
}
}
if matches!(shape, SyntaxShape::Closure(_)) || matches!(shape, SyntaxShape::Any) {
return parse_closure_expression(working_set, shape, span, expand_aliases_denylist);
} else if matches!(shape, SyntaxShape::Block) {
return parse_block_expression(working_set, shape, span, expand_aliases_denylist);
} else if matches!(shape, SyntaxShape::Record) {
return parse_record(working_set, span, expand_aliases_denylist);
} else {
return (
Expression::garbage(span),
Some(ParseError::Expected(
format!("non-block value: {shape}"),
span,
)),
);
}
}
b'(' => return parse_paren_expr(working_set, span, expand_aliases_denylist),
b'{' => return parse_brace_expr(working_set, span, shape, expand_aliases_denylist),
b'[' => match shape {
SyntaxShape::Any
| SyntaxShape::List(_)