red/rustlings
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

Merge 2dc93cadda into cdd8e19716

Browse source
This commit is contained in:
Taylor Yu 2021-07-05 16:22:01 -07:00 committed by GitHub
parent cdd8e19716 2dc93cadda
commit 492beea588
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
3 changed files with 127 additions and 56 deletions

56
exercises/conversions/from_str.rs
View file

@ -1,16 +1,31 @@
// This does practically the same thing that TryFrom<&str> does.
// from_str.rs
// This is similar to from_into.rs, but this time we'll implement `FromStr`
// and return errors instead of falling back to a default value.
// Additionally, upon implementing FromStr, you can use the `parse` method
// on strings to generate an object of the implementor type.
// You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
use std::error;
use std::num::ParseIntError;
use std::str::FromStr;
#[derive(Debug)]
#[derive(Debug, PartialEq)]
struct Person {
name: String,
age: usize,
}
// We will use this error type for the `FromStr` implementation.
#[derive(Debug, PartialEq)]
enum ParsePersonError {
// Empty input string
Empty,
// Incorrect number of fields
BadLen,
// Empty name field
NoName,
// Wrapped error from parse::<usize>()
ParseInt(ParseIntError),
}
// I AM NOT DONE
// Steps:
@ -24,7 +39,7 @@ struct Person {
// If everything goes well, then return a Result of a Person object
impl FromStr for Person {
type Err = Box<dyn error::Error>;
type Err = ParsePersonError;
fn from_str(s: &str) -> Result<Person, Self::Err> {
}
}
@ -40,7 +55,7 @@ mod tests {
#[test]
fn empty_input() {
assert!("".parse::<Person>().is_err());
assert_eq!("".parse::<Person>(), Err(ParsePersonError::Empty));
}
#[test]
fn good_input() {
@ -52,41 +67,56 @@ mod tests {
}
#[test]
fn missing_age() {
assert!("John,".parse::<Person>().is_err());
assert!(matches!(
"John,".parse::<Person>(),
Err(ParsePersonError::ParseInt(_))
));
}
#[test]
fn invalid_age() {
assert!("John,twenty".parse::<Person>().is_err());
assert!(matches!(
"John,twenty".parse::<Person>(),
Err(ParsePersonError::ParseInt(_))
));
}
#[test]
fn missing_comma_and_age() {
assert!("John".parse::<Person>().is_err());
assert_eq!("John".parse::<Person>(), Err(ParsePersonError::BadLen));
}
#[test]
fn missing_name() {
assert!(",1".parse::<Person>().is_err());
assert_eq!(",1".parse::<Person>(), Err(ParsePersonError::NoName));
}
#[test]
fn missing_name_and_age() {
assert!(",".parse::<Person>().is_err());
assert!(matches!(
",".parse::<Person>(),
Err(ParsePersonError::NoName | ParsePersonError::ParseInt(_))
));
}
#[test]
fn missing_name_and_invalid_age() {
assert!(",one".parse::<Person>().is_err());
assert!(matches!(
",one".parse::<Person>(),
Err(ParsePersonError::NoName | ParsePersonError::ParseInt(_))
));
}
#[test]
fn trailing_comma() {
assert!("John,32,".parse::<Person>().is_err());
assert_eq!("John,32,".parse::<Person>(), Err(ParsePersonError::BadLen));
}
#[test]
fn trailing_comma_and_some_string() {
assert!("John,32,man".parse::<Person>().is_err());
assert_eq!(
"John,32,man".parse::<Person>(),
Err(ParsePersonError::BadLen)
);
}
}

74
exercises/conversions/try_from_into.rs
View file

@ -1,9 +1,9 @@
// try_from_into.rs
// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances.
// Basically, this is the same as From. The main difference is that this should return a Result type
// instead of the target type itself.
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
use std::convert::{TryFrom, TryInto};
use std::error;
#[derive(Debug, PartialEq)]
struct Color {
@ -12,12 +12,21 @@ struct Color {
blue: u8,
}
// We will use this error type for these `TryFrom` conversions.
#[derive(Debug, PartialEq)]
enum IntoColorError {
// Incorrect length of slice
BadLen,
// Integer conversion error
IntConversion,
}
// I AM NOT DONE
// Your task is to complete this implementation
// and return an Ok result of inner type Color.
// You need to create an implementation for a tuple of three integers,
// an array of three integers and a slice of integers.
// an array of three integers, and a slice of integers.
//
// Note that the implementation for tuple and array will be checked at compile time,
// but the slice implementation needs to check the slice length!
@ -25,20 +34,23 @@ struct Color {
// Tuple implementation
impl TryFrom<(i16, i16, i16)> for Color {
type Error = Box<dyn error::Error>;
fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {}
type Error = IntoColorError;
fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
}
}
// Array implementation
impl TryFrom<[i16; 3]> for Color {
type Error = Box<dyn error::Error>;
fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {}
type Error = IntoColorError;
fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
}
}
// Slice implementation
impl TryFrom<&[i16]> for Color {
type Error = Box<dyn error::Error>;
fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {}
type Error = IntoColorError;
fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
}
}
fn main() {
@ -46,15 +58,15 @@ fn main() {
let c1 = Color::try_from((183, 65, 14));
println!("{:?}", c1);
// Since From is implemented for Color, we should be able to use Into
// Since TryFrom is implemented for Color, we should be able to use TryInto
let c2: Result<Color, _> = [183, 65, 14].try_into();
println!("{:?}", c2);
let v = vec![183, 65, 14];
// With slice we should use `from` function
// With slice we should use `try_from` function
let c3 = Color::try_from(&v[..]);
println!("{:?}", c3);
// or take slice within round brackets and use Into
// or take slice within round brackets and use TryInto
let c4: Result<Color, _> = (&v[..]).try_into();
println!("{:?}", c4);
}
@ -65,15 +77,24 @@ mod tests {
#[test]
fn test_tuple_out_of_range_positive() {
assert!(Color::try_from((256, 1000, 10000)).is_err());
assert_eq!(
Color::try_from((256, 1000, 10000)),
Err(IntoColorError::IntConversion)
);
}
#[test]
fn test_tuple_out_of_range_negative() {
assert!(Color::try_from((-1, -10, -256)).is_err());
assert_eq!(
Color::try_from((-1, -10, -256)),
Err(IntoColorError::IntConversion)
);
}
#[test]
fn test_tuple_sum() {
assert!(Color::try_from((-1, 255, 255)).is_err());
assert_eq!(
Color::try_from((-1, 255, 255)),
Err(IntoColorError::IntConversion)
);
}
#[test]
fn test_tuple_correct() {
@ -91,17 +112,17 @@ mod tests {
#[test]
fn test_array_out_of_range_positive() {
let c: Result<Color, _> = [1000, 10000, 256].try_into();
assert!(c.is_err());
assert_eq!(c, Err(IntoColorError::IntConversion));
}
#[test]
fn test_array_out_of_range_negative() {
let c: Result<Color, _> = [-10, -256, -1].try_into();
assert!(c.is_err());
assert_eq!(c, Err(IntoColorError::IntConversion));
}
#[test]
fn test_array_sum() {
let c: Result<Color, _> = [-1, 255, 255].try_into();
assert!(c.is_err());
assert_eq!(c, Err(IntoColorError::IntConversion));
}
#[test]
fn test_array_correct() {
@ -119,17 +140,26 @@ mod tests {
#[test]
fn test_slice_out_of_range_positive() {
let arr = [10000, 256, 1000];
assert!(Color::try_from(&arr[..]).is_err());
assert_eq!(
Color::try_from(&arr[..]),
Err(IntoColorError::IntConversion)
);
}
#[test]
fn test_slice_out_of_range_negative() {
let arr = [-256, -1, -10];
assert!(Color::try_from(&arr[..]).is_err());
assert_eq!(
Color::try_from(&arr[..]),
Err(IntoColorError::IntConversion)
);
}
#[test]
fn test_slice_sum() {
let arr = [-1, 255, 255];
assert!(Color::try_from(&arr[..]).is_err());
assert_eq!(
Color::try_from(&arr[..]),
Err(IntoColorError::IntConversion)
);
}
#[test]
fn test_slice_correct() {
@ -148,11 +178,11 @@ mod tests {
#[test]
fn test_slice_excess_length() {
let v = vec![0, 0, 0, 0];
assert!(Color::try_from(&v[..]).is_err());
assert_eq!(Color::try_from(&v[..]), Err(IntoColorError::BadLen));
}
#[test]
fn test_slice_insufficient_length() {
let v = vec![0, 0];
assert!(Color::try_from(&v[..]).is_err());
assert_eq!(Color::try_from(&v[..]), Err(IntoColorError::BadLen));
}
}

53
info.toml
View file

@ -936,6 +936,27 @@ mode = "test"
hint = """
Follow the steps provided right before the `From` implementation"""
[[exercises]]
name = "from_str"
path = "exercises/conversions/from_str.rs"
mode = "test"
hint = """
The implementation of FromStr should return an Ok with a Person object,
or an Err with an error if the string is not valid.
This is almost like the `from_into` exercise, but returning errors instead
of falling back to a default value.
Hint: Look at the test cases to see which error variants to return.
Another hint: You can use the `map_err` method of `Result` with a function
or a closure to wrap the error from `parse::<usize>`.
Yet another hint: If you would like to propagate errors by using the `?`
operator in your solution, you might want to look at
https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reenter_question_mark.html
"""
[[exercises]]
name = "try_from_into"
path = "exercises/conversions/try_from_into.rs"
@ -944,17 +965,19 @@ hint = """
Follow the steps provided right before the `TryFrom` implementation.
You can also use the example at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
You might want to look back at the exercise errors5 (or its hints) to remind
yourself about how `Box<dyn Error>` works.
Hint: Is there an implementation of `TryFrom` in the standard library that
can both do the required integer conversion and check the range of the input?
If you're trying to return a string as an error, note that neither `str`
nor `String` implements `error::Error`. However, there is an implementation
of `From<&str>` for `Box<dyn Error>`. This means you can use `.into()` or
the `?` operator to convert your string into the correct error type.
Another hint: Look at the test cases to see which error variants to return.
If you're having trouble with using the `?` operator to convert an error string,
recall that `?` works to convert `Err(something)` into the appropriate error
type for returning from the function."""
Yet another hint: You can use the `map_err` or `or` methods of `Result` to
convert errors.
Yet another hint: If you would like to propagate errors by using the `?`
operator in your solution, you might want to look at
https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reenter_question_mark.html
Challenge: Can you make the `TryFrom` implementations generic over many integer types?"""
[[exercises]]
name = "as_ref_mut"
@ -962,15 +985,3 @@ path = "exercises/conversions/as_ref_mut.rs"
mode = "test"
hint = """
Add AsRef<str> as a trait bound to the functions."""
[[exercises]]
name = "from_str"
path = "exercises/conversions/from_str.rs"
mode = "test"
hint = """
The implementation of FromStr should return an Ok with a Person object,
or an Err with an error if the string is not valid.
This is almost like the `try_from_into` exercise.
If you're having trouble with returning the correct error type, see the
hints for try_from_into."""