diff --git a/build.rs b/build.rs new file mode 100644 index 0000000..3c2e7dc --- /dev/null +++ b/build.rs @@ -0,0 +1,64 @@ +use std::fs::File; +use std::io::Write; +use std::path::Path; +use std::env; +use std::string::String; + +/// Generate the name of the swizzle function and what it returns. +/// NOTE: This function assumes that variables are in ASCII format +fn gen_swizzle_nth(variables: &'static str, mut i: usize) -> (String, String) { + let mut swizzle_impl = String::new(); + let mut swizzle = String::new(); + let n = variables.len(); + for _ in 0..n { + let c = variables.as_bytes()[i%n] as char; + swizzle.push(c); + swizzle_impl.push_str(&format!("self.{}, ", c)); + i = i/n; + } + (swizzle, swizzle_impl) +} + +/// This script generates the swizzle operators that are included in macros.rs +/// NOTE: This function assumes that variables are in ASCII format +fn gen_swizzle_functions(variables: &'static str) -> String { + let n = variables.len(); + let vec_type = format!("$vector_type{}", n); + let mut result = String::new(); + let nn = n.pow(n as u32); + for i in 0..nn { + let (swizzle_name, swizzle_impl) = gen_swizzle_nth(variables, i); + result.push_str( + &format!(" #[inline] pub fn {0}(&self) -> {2}<$S> {{ {2}::new({1}) }}\n", + swizzle_name, swizzle_impl, vec_type)); + } + result +} + +fn main() { + // The following scripts generates a macro for building swizzle operators for multidimensional + // vectors or points. + let out_dir = env::var("OUT_DIR").unwrap(); + let swizzle_file_path = Path::new(&out_dir).join("swizzle_operator_macro.rs"); + + let data = format!( +"/// Generate glm/glsl style swizzle operators +macro_rules! impl_swizzle_functions {{ + ($vector_type2:ident, $S:ident, xy) => {{ +{xy} + }}; + ($vector_type2:ident, $vector_type3:ident, $S:ident, xyz) => {{ + impl_swizzle_functions!($vector_type2, $S, xy); +{xyz} + }}; + ($vector_type2:ident, $vector_type3:ident, $vector_type4:ident, $S:ident, xyzw) => {{ + impl_swizzle_functions!($vector_type2, $vector_type3, $S, xyz); +{xyzw} + }}; +}}", xy=gen_swizzle_functions("xy"), + xyz=gen_swizzle_functions("xyz"), + xyzw=gen_swizzle_functions("xyzw")); + let mut f = File::create(swizzle_file_path) + .expect("Unable to create file that defines the swizzle operator macro."); + f.write_all(data.as_bytes()).expect("Unable to write swizzle operator macro."); +} diff --git a/src/macros.rs b/src/macros.rs index 768c4fd..573c597 100644 --- a/src/macros.rs +++ b/src/macros.rs @@ -476,3 +476,5 @@ macro_rules! impl_mint_conversions { } } } + +include!(concat!(env!("OUT_DIR"), "/swizzle_operator_macro.rs"));