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Cell paths: make optional path members short-circuit (#8554)

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This is a follow-up to https://github.com/nushell/nushell/pull/8379 and
https://github.com/nushell/nushell/discussions/8502.

This PR makes it so that the new `?` syntax for marking a path member as
optional short-circuits, as voted on in the
[8502](https://github.com/nushell/nushell/discussions/8502) poll.
Previously, `{ foo: 123 }.bar?.baz` would raise an error:

```
> { foo: 123 }.bar?.baz
  × Data cannot be accessed with a cell path
   ╭─[entry #15:1:1]
 1 │ { foo: 123 }.bar?.baz
   ·                   ─┬─
   ·                    ╰── nothing doesn't support cell paths
   ╰────
   ```

Here's what was happening:

1. The `bar?` path member access returns `nothing` because there is no field named `bar` on the record
2. The `baz` path member access fails when trying to access a `baz` field on that `nothing` value

After this change, `{ foo: 123 }.bar?.baz` returns `nothing`; the failed `bar?` access immediately returns `nothing` and the `baz` access never runs.
This commit is contained in:
Reilly Wood
2023-03-22 13:54:19 -07:00
committed by GitHub
parent 2f8a52d256
commit 6a274b860a
2 changed files with 22 additions and 10 deletions
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17
crates/nu-protocol/src/value/mod.rs
View File

@ -742,7 +742,7 @@ impl Value {
if let Some(item) = val.get(*count) {
current = item.clone();
} else if *optional {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
} else if val.is_empty() {
err_or_null!(
ShellError::AccessEmptyContent { span: *origin_span },
@ -762,7 +762,7 @@ impl Value {
if let Some(item) = val.get(*count) {
current = Value::int(*item as i64, *origin_span);
} else if *optional {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
} else if val.is_empty() {
err_or_null!(
ShellError::AccessEmptyContent { span: *origin_span },
@ -782,7 +782,7 @@ impl Value {
if let Some(item) = val.clone().into_range_iter(None)?.nth(*count) {
current = item.clone();
} else if *optional {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
} else {
err_or_null!(
ShellError::AccessBeyondEndOfStream { span: *origin_span },
@ -795,7 +795,8 @@ impl Value {
Ok(val) => val,
Err(err) => {
if *optional {
Value::nothing(*origin_span)
return Ok(Value::nothing(*origin_span));
// short-circuit
} else {
return Err(err);
}
@ -803,7 +804,7 @@ impl Value {
};
}
Value::Nothing { .. } if *optional => {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
}
// Records (and tables) are the only built-in which support column names,
// so only use this message for them.
@ -843,7 +844,7 @@ impl Value {
}) {
current = found.1.clone();
} else if *optional {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
} else {
if from_user_input {
if let Some(suggestion) = did_you_mean(&cols, column_name) {
@ -869,7 +870,7 @@ impl Value {
if columns.contains(&column_name.as_str()) {
current = val.get_column_value(column_name)?;
} else if *optional {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
} else {
if from_user_input {
if let Some(suggestion) = did_you_mean(&columns, column_name) {
@ -934,7 +935,7 @@ impl Value {
current = val.follow_path_string(column_name.clone(), *origin_span)?;
}
Value::Nothing { .. } if *optional => {
current = Value::nothing(*origin_span);
return Ok(Value::nothing(*origin_span)); // short-circuit
}
Value::Error { error } => err_or_null!(*error.to_owned(), *origin_span),
x => {