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Interpreting ranges for substring (#2499)

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Abhi V 2020-09-06 22:05:11 +05:30 committed by GitHub
parent e2cbc4e853
commit 79cc725aff
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1 changed files with 32 additions and 52 deletions
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84
crates/nu-cli/src/commands/str_/substring.rs
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@ -8,7 +8,6 @@ use nu_protocol::{
use nu_source::Tag;
use nu_value_ext::{as_string, ValueExt};
use std::cmp;
use std::cmp::Ordering;
use std::convert::TryInto;
@ -64,9 +63,9 @@ impl WholeStreamCommand for SubCommand {
result: Some(vec![Value::from("nushell")]),
},
Example {
description: "Get the last characters from the string",
description: "Drop the last `n` characters from the string",
example: "echo 'good nushell' | str substring ',-5'",
result: Some(vec![Value::from("shell")]),
result: Some(vec![Value::from("good nu")]),
},
Example {
description: "Get the remaining characters from a starting index",
@ -141,8 +140,16 @@ fn action(input: &Value, options: &Substring, tag: impl Into<Tag>) -> Result<Val
)
})?;
let start: isize = options.0;
let end: isize = options.1;
let start: isize = if options.0 < 0 {
options.0 + len
} else {
options.0
};
let end: isize = if options.1 < 0 {
std::cmp::max(len + options.1, 0)
} else {
options.1
};
if start < len && end >= 0 {
match start.cmp(&end) {
@ -152,42 +159,14 @@ fn action(input: &Value, options: &Substring, tag: impl Into<Tag>) -> Result<Val
"End must be greater than or equal to Start",
tag.span,
)),
Ordering::Less => {
let end: isize = cmp::min(options.1, len);
Ok(UntaggedValue::string(
s.chars()
.skip(start as usize)
.take((end - start) as usize)
.collect::<String>(),
)
.into_value(tag))
}
Ordering::Less => Ok(UntaggedValue::string(
s.chars()
.skip(start as usize)
.take((end - start) as usize)
.collect::<String>(),
)
.into_value(tag)),
}
} else if start >= 0 && end <= 0 {
let end = options.1.abs();
let reversed = s
.chars()
.skip(start as usize)
.take((len - start) as usize)
.collect::<String>();
let reversed = if start == 0 {
reversed
} else {
s.chars().take(start as usize).collect::<String>()
};
let reversed = reversed
.chars()
.rev()
.take(end as usize)
.collect::<String>();
Ok(
UntaggedValue::string(reversed.chars().rev().collect::<String>())
.into_value(tag),
)
} else {
Ok(UntaggedValue::string("").into_value(tag))
}
@ -344,19 +323,20 @@ mod tests {
expectation("andr", (0, 4)),
expectation("andre", (0, 5)),
expectation("andres", (0, 6)),
expectation("andres", (0, -6)),
expectation("ndres", (0, -5)),
expectation("dres", (0, -4)),
expectation("res", (0, -3)),
expectation("es", (0, -2)),
expectation("s", (0, -1)),
expectation("", (0, -6)),
expectation("a", (0, -5)),
expectation("an", (0, -4)),
expectation("and", (0, -3)),
expectation("andr", (0, -2)),
expectation("andre", (0, -1)),
expectation("", (0, -110)),
expectation("", (6, 0)),
expectation("s", (6, -1)),
expectation("es", (6, -2)),
expectation("res", (6, -3)),
expectation("dres", (6, -4)),
expectation("ndres", (6, -5)),
expectation("andres", (6, -6)),
expectation("", (6, -1)),
expectation("", (6, -2)),
expectation("", (6, -3)),
expectation("", (6, -4)),
expectation("", (6, -5)),
expectation("", (6, -6)),
];
for expectation in cases.iter() {