76f00b7941
For example this is now valid:
```
let p2 = Point2::new(1.0, 2.0);
let p3 = p2.xyx(); // producing Point3 { x:1.0, y:2.0, z:1.0 }
```
86 lines
3.4 KiB
Rust
86 lines
3.4 KiB
Rust
use std::fs::File;
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use std::io::Write;
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use std::path::Path;
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use std::env;
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use std::string::String;
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/// Generate the name of the swizzle function and what it returns.
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/// NOTE: This function assumes that variables are in ASCII format
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fn gen_swizzle_nth<'a>(variables: &'a str, mut i: usize, upto: usize) -> Option<(String, String)> {
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debug_assert!(i > 0); // zeroth permutation is empty
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let mut swizzle_impl = String::new();
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let mut swizzle = String::new();
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let n = variables.len()+1;
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for _ in 0..upto {
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if i == 0 { break; }
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if i % n == 0 { return None; }
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let c = variables.as_bytes()[i%n - 1] as char;
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swizzle.push(c);
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swizzle_impl.push_str(&format!("self.{}, ", c));
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i = i/n;
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}
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Some((swizzle, swizzle_impl))
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}
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/// A function that generates swizzle functions as a string.
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/// `variables`: swizzle variables (e.g. "xyz")
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/// `upto`: largest output vector size (e.g. for `variables = "xy"` and `upto = 4`, `xyxy()` is a
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/// valid swizzle operator.
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/// NOTE: This function assumes that variables are in ASCII format
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fn gen_swizzle_functions(variables: &'static str, upto: usize) -> String {
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let mut result = String::new();
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let nn = (variables.len()+1).pow(upto as u32);
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for i in 1..nn {
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if let Some((swizzle_name, swizzle_impl)) = gen_swizzle_nth(variables, i, upto) {
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let vec_type = format!("$vector_type{}", swizzle_name.len());
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result.push_str(
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&format!(" #[inline] pub fn {0}(&self) -> {2}<$S> {{ {2}::new({1}) }}\n",
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swizzle_name, swizzle_impl, vec_type));
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}
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}
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result
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}
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/// This script generates the macro for building swizzle operators for multidimensional
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/// vectors and points. This macro is included in macros.rs
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fn main() {
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// save the file to output directory
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let out_dir = env::var("OUT_DIR").unwrap();
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let swizzle_file_path = Path::new(&out_dir).join("swizzle_operator_macro.rs");
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// This is the string representing the generated macro
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let data = format!(
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"/// Generate glm/glsl style swizzle operators
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macro_rules! impl_swizzle_functions {{
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $S:ident, x) => {{
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{x3}
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}};
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $S:ident, xy) => {{
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{xy3}
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}};
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $S:ident, xyz) => {{
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{xyz3}
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}};
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $vector_type4:ident, $S:ident, x) => {{
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{x4}
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}};
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $vector_type4:ident, $S:ident, xy) => {{
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{xy4}
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}};
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $vector_type4:ident, $S:ident, xyz) => {{
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{xyz4}
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}};
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($vector_type1:ident, $vector_type2:ident, $vector_type3:ident, $vector_type4:ident, $S:ident, xyzw) => {{
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{xyzw4}
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}};
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}}", x3=gen_swizzle_functions("x",3),
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xy3=gen_swizzle_functions("xy",3),
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xyz3=gen_swizzle_functions("xyz",3),
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x4=gen_swizzle_functions("x",4),
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xy4=gen_swizzle_functions("xy",4),
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xyz4=gen_swizzle_functions("xyz",4),
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xyzw4=gen_swizzle_functions("xyzw",4));
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let mut f = File::create(swizzle_file_path)
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.expect("Unable to create file that defines the swizzle operator macro.");
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f.write_all(data.as_bytes()).expect("Unable to write swizzle operator macro.");
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}
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