143 lines
3.9 KiB
Rust
143 lines
3.9 KiB
Rust
//! External names.
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//!
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//! These are identifiers for declaring entities defined outside the current
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//! function. The name of an external declaration doesn't have any meaning to
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//! Cretonne, which compiles functions independently.
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use std::fmt::{self, Write};
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use std::ascii::AsciiExt;
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/// The name of an external can be any sequence of bytes.
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///
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/// External names are primarily used as keys by code using Cretonne to map
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/// from a cretonne::ir::FuncRef or similar to additional associated data.
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///
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/// External names can also serve as a primitive testing and debugging tool.
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/// In particular, many `.cton` test files use function names to identify
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/// functions.
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#[derive(Debug, Clone, PartialEq, Eq, Default, Hash)]
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pub struct ExternalName(NameRepr);
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impl ExternalName {
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/// Creates a new external name from a sequence of bytes.
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///
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/// # Examples
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///
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/// ```rust
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/// # use cretonne::ir::ExternalName;
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/// // Create `ExternalName` from a string.
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/// let name = ExternalName::new("hello");
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/// assert_eq!(name.to_string(), "%hello");
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///
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/// // Create `ExternalName` from a sequence of bytes.
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/// let bytes: &[u8] = &[10, 9, 8];
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/// let name = ExternalName::new(bytes);
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/// assert_eq!(name.to_string(), "#0a0908");
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/// ```
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pub fn new<T>(v: T) -> ExternalName
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where
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T: Into<Vec<u8>>,
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{
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let vec = v.into();
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if vec.len() <= NAME_LENGTH_THRESHOLD {
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let mut bytes = [0u8; NAME_LENGTH_THRESHOLD];
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for (i, &byte) in vec.iter().enumerate() {
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bytes[i] = byte;
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}
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ExternalName(NameRepr::Short {
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length: vec.len() as u8,
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bytes: bytes,
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})
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} else {
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ExternalName(NameRepr::Long(vec))
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}
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}
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}
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/// Tries to interpret bytes as ASCII alphanumerical characters and `_`.
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fn try_as_name(bytes: &[u8]) -> Option<String> {
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let mut name = String::with_capacity(bytes.len());
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for c in bytes.iter().map(|&b| b as char) {
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if c.is_ascii() && c.is_alphanumeric() || c == '_' {
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name.push(c);
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} else {
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return None;
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}
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}
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Some(name)
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}
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const NAME_LENGTH_THRESHOLD: usize = 22;
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#[derive(Debug, Clone, PartialEq, Eq, Hash)]
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enum NameRepr {
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Short {
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length: u8,
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bytes: [u8; NAME_LENGTH_THRESHOLD],
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},
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Long(Vec<u8>),
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}
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impl AsRef<[u8]> for NameRepr {
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fn as_ref(&self) -> &[u8] {
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match *self {
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NameRepr::Short { length, ref bytes } => &bytes[0..length as usize],
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NameRepr::Long(ref vec) => vec.as_ref(),
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}
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}
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}
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impl AsRef<[u8]> for ExternalName {
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fn as_ref(&self) -> &[u8] {
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self.0.as_ref()
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}
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}
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impl Default for NameRepr {
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fn default() -> Self {
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NameRepr::Short {
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length: 0,
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bytes: [0; NAME_LENGTH_THRESHOLD],
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}
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}
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}
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impl fmt::Display for ExternalName {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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if let Some(name) = try_as_name(self.0.as_ref()) {
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write!(f, "%{}", name)
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} else {
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f.write_char('#')?;
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for byte in self.0.as_ref() {
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write!(f, "{:02x}", byte)?;
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}
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Ok(())
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::ExternalName;
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#[test]
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fn displaying() {
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assert_eq!(ExternalName::new("").to_string(), "%");
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assert_eq!(ExternalName::new("x").to_string(), "%x");
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assert_eq!(ExternalName::new("x_1").to_string(), "%x_1");
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assert_eq!(ExternalName::new(" ").to_string(), "#20");
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assert_eq!(
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ExternalName::new("кретон").to_string(),
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"#d0bad180d0b5d182d0bed0bd"
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);
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assert_eq!(
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ExternalName::new("印花棉布").to_string(),
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"#e58db0e88ab1e6a389e5b883"
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);
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assert_eq!(
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ExternalName::new(vec![0, 1, 2, 3, 4, 5]).to_string(),
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"#000102030405"
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);
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}
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}
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