Struct knightrs::environment::Environment

pub struct Environment<'i, 'o, 'c> { /* fields omitted */ }

The execution environment for Knight programs.

To aid in embedding Knight in other systems, the Environment provides complete control over the stdin, stdout, and output of the “system” (`), in addition to keeping track of all relevant variables. Because of this, the environment must always be passed when calling Value::run.

This is in contrast with most other Knight implementations, which usually have a singular, global “environment”, and

Examples

let mut env = Environment::new();

// Write to stdout.
writeln!(env, "Hello, world!");

// Read from stdin.
let mut str = String::new();
env.read_to_string(&mut str).expect("cant read from stdin!");

// execute command
println!("The stdout of `ls -al` is {}", env.system("ls -al").expect("`ls -al` failed"));

// create a variable
let var = env.get("foobar");
assert_eq!(var, env.get("foobar")); // both variables are the same.

Implementations

impl<'i, 'o, 'c> Environment<'i, 'o, 'c>

#[must_use = "simply creating an environment doesn't do anything."]

pub fn new() -> Self

Creates an empty Environment.

Examples

let env = Environment::new();

// ...do stuff with `env`.

#[must_use = "simply creating a builder does nothing."]

pub fn builder() -> Builder<'i, 'o, 'c>

Creates a new Builder.

This is simply a helper function, and is provided so that you don’t have to import Builder.

Examples

let env = Environment::builder().disable_system().build();

// ... do stuff with `env`.

pub fn get<N: AsRef<str> + ToString + ?Sized>(&mut self, name: &N) -> Variable

Retrieves the variable with the given name.

This method will always succeed; if this is the first time that name has been seen by self, a new (unassigned ) variable will be created.

Examples

let mut env = Environment::new();
let var = env.get("plato");

assert_eq!(var, env.get("plato"));

pub fn system(&mut self, cmd: &str) -> Result<Text, Error>

Executes cmd as a system command, returning the stdout of the child process.

This will internally call the value that was set for Builder::system. See that function for more details on, eg, the default value.

Examples

let mut env = Environment::new();

assert_eq!(env.system("echo 'hello, knight!'").unwrap().as_str(), "hello, knight!\n");

pub fn run_str<S: AsRef<str>>(&mut self, input: S) -> Result<Value, Error>

Runs the given string as Knight code, returning the result of its execution.

pub fn run<I>(&mut self, input: I) -> Result<Value, Error> where
    I: IntoIterator<Item = char>, 

Parses a Value from the given iterator and then runs the value.

Trait Implementations

impl Debug for Environment<'_, '_, '_>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Environment<'_, '_, '_>

fn default() -> Self

Returns the “default value” for a type.

impl Read for Environment<'_, '_, '_>

fn read(&mut self, data: &mut [u8]) -> Result<usize>

Read bytes into data from self’s stdin.

The stdin can be customized at creation via Builder::stdin.

pub fn read_vectored(
    &mut self,
    bufs: &mut [IoSliceMut<'_>]
) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

pub fn is_read_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

pub unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

pub fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

pub fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

pub fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

pub fn by_ref(&mut self) -> &mut Self

Creates a “by reference” adaptor for this instance of Read.

pub fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an Iterator over its bytes.

pub fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read, 

Creates an adaptor which will chain this stream with another.

pub fn take(self, limit: u64) -> Take<Self>

Creates an adaptor which will read at most limit bytes from it.

impl Write for Environment<'_, '_, '_>

fn write(&mut self, data: &[u8]) -> Result<usize>

Writes data’s bytes into self’s stdout.

The stdin can be customized at creation via Builder::stdin.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

pub fn is_write_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

pub fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

pub fn write_all_vectored(
    &mut self,
    bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>

🔬 This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

pub fn by_ref(&mut self) -> &mut Self

Creates a “by reference” adaptor for this instance of Write.