include_js_core/lib.rs
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#![feature(const_fn_transmute)]
use std::{borrow::Borrow, ops::Deref};
use std::convert::TryFrom;
pub type JSParseError = boa::syntax::parser::ParseError;
/// Wrapper around `str` that ensures it contains _syntactically_ valid Javascript.
/// This is the borrowed version of `JSString` so `&JSStr` is to `JSString` what `&str` is to `String`
#[repr(transparent)]
pub struct JSStr {
data: str,
}
/// Wrapper around `String` that ensures it contains _syntactically_ valid Javascript.
/// See docs for `JSStr` for more info.
pub struct JSString {
code: String,
}
pub trait JSTemplate {
fn render_template(&self) -> JSString;
}
impl JSStr {
/// Checks if the content of `js` is syntactically valid Javascript before
/// coersing it to `&JSStr`
///
/// # Examples
///
/// ```rust
/// use include_js::JSStr;
///
/// let js_str = JSStr::new("function f() {}");
/// assert!(js_str.is_ok());
/// ```
///
/// ```rust
/// use include_js::JSStr;
///
/// let js_str = JSStr::new("#include <vector>");
/// assert!(js_str.is_err());
/// ```
pub fn new(js: &str) -> Result<&Self, JSParseError> {
let _ = boa::parse(js, false)?;
// SAFETY: follows from safety of `new_unchecked` and from the line above
Ok(unsafe { JSStr::new_unchecked(js) })
}
/// Coerses `js` directly into a `&JSStr` without checking for validity
pub const unsafe fn new_unchecked(js: &str) -> &Self {
// SAFETY: JSStr is repr(transparent) and contains `str` so transmuting from &str to &JSStr is safe
std::mem::transmute(js)
}
/// Converts the `&JSStr` back into an `&str`, this should be a noop.
pub fn as_str(&self) -> &str {
&self.data
}
}
impl<'a> TryFrom<&'a str> for &'a JSStr {
type Error = JSParseError;
fn try_from(value: &'a str) -> Result<Self, Self::Error> {
JSStr::new(value)
}
}
impl AsRef<JSStr> for JSStr {
fn as_ref(&self) -> &JSStr {
self
}
}
impl AsRef<str> for JSStr {
fn as_ref(&self) -> &str {
&self.data
}
}
impl<'a> Into<&'a str> for &'a JSStr {
fn into(self) -> &'a str {
&self.data
}
}
impl ToOwned for JSStr {
type Owned = JSString;
fn to_owned(&self) -> Self::Owned {
// SAFETY: self.as_str() comes from JSStr so it must be valid javascript
unsafe {
JSString::new_unchecked(self.as_str().to_owned())
}
}
}
impl JSString {
pub fn new(code: String) -> Result<Self, JSParseError> {
let _ = JSStr::new(&code)?;
Ok(JSString{ code })
}
pub unsafe fn new_unchecked(code: String) -> Self {
JSString{ code }
}
pub fn into_string(self) -> String {
self.code
}
}
impl TryFrom<String> for JSString {
type Error = JSParseError;
fn try_from(value: String) -> Result<Self, Self::Error> {
JSString::new(value)
}
}
impl Into<String> for JSString {
fn into(self) -> String {
self.code
}
}
impl Borrow<JSStr> for JSString {
fn borrow(&self) -> &JSStr {
// SAFETY: we are already in JSString so `code` must be valid javascript
unsafe { JSStr::new_unchecked(&self.code) }
}
}
impl AsRef<JSStr> for JSString {
fn as_ref(&self) -> &JSStr {
self.borrow()
}
}
impl Deref for JSString {
type Target = JSStr;
fn deref(&self) -> &Self::Target {
// SAFETY: we are already in JSString so `code` must be valid javascript
unsafe { JSStr::new_unchecked(&self.code) }
}
}