|
| 1 | +use std::env; |
| 2 | +use std::fs::File; |
| 3 | +use std::io::Write; |
| 4 | +use std::path::Path; |
| 5 | + |
| 6 | +const LOWER_LIMIT: usize = 16; |
| 7 | + |
| 8 | +fn main() { |
| 9 | + let limit = if cfg!(feature="limit_2048") { |
| 10 | + 2048 |
| 11 | + } else if cfg!(feature="limit_1024") { |
| 12 | + 1024 |
| 13 | + } else if cfg!(feature="limit_512") { |
| 14 | + 512 |
| 15 | + } else if cfg!(feature="limit_256") { |
| 16 | + 256 |
| 17 | + } else if cfg!(feature="limit_128") { |
| 18 | + 128 |
| 19 | + } else { |
| 20 | + 64 |
| 21 | + }; |
| 22 | + |
| 23 | + let out_dir = env::var("OUT_DIR").unwrap(); |
| 24 | + let dest_path = Path::new(&out_dir).join("lib.rs"); |
| 25 | + let mut f = File::create(&dest_path).unwrap(); |
| 26 | + |
| 27 | + let mut output = String::new(); |
| 28 | + |
| 29 | + output.push_str(r#" |
| 30 | +/// Unroll the given for loop |
| 31 | +/// |
| 32 | +/// Example: |
| 33 | +/// |
| 34 | +/// ```ignore |
| 35 | +/// unroll! { |
| 36 | +/// for i in 0..5 { |
| 37 | +/// println!("Iteration {}", i); |
| 38 | +/// } |
| 39 | +/// } |
| 40 | +/// ``` |
| 41 | +/// |
| 42 | +/// will expand into: |
| 43 | +/// |
| 44 | +/// ```ignore |
| 45 | +/// { println!("Iteration {}", 0); } |
| 46 | +/// { println!("Iteration {}", 1); } |
| 47 | +/// { println!("Iteration {}", 2); } |
| 48 | +/// { println!("Iteration {}", 3); } |
| 49 | +/// { println!("Iteration {}", 4); } |
| 50 | +/// ``` |
| 51 | +#[macro_export] |
| 52 | +macro_rules! unroll { |
| 53 | + (for $v:ident in 0..0 $c:block) => {}; |
| 54 | +
|
| 55 | + (for $v:ident < $max:tt in ($start:tt..$end:tt).step_by($val:expr) {$($c:tt)*}) => { |
| 56 | + { |
| 57 | + let step = $val; |
| 58 | + let start = $start; |
| 59 | + let end = start + ($end - start) / step; |
| 60 | + unroll! { |
| 61 | + for val < $max in start..end { |
| 62 | + let $v: usize = ((val - start) * step) + start; |
| 63 | +
|
| 64 | + $($c)* |
| 65 | + } |
| 66 | + } |
| 67 | + } |
| 68 | + }; |
| 69 | +
|
| 70 | + (for $v:ident in ($start:tt..$end:tt).step_by($val:expr) {$($c:tt)*}) => { |
| 71 | + unroll! { |
| 72 | + for $v < $end in ($start..$end).step_by($val) {$($c)*} |
| 73 | + } |
| 74 | + }; |
| 75 | +
|
| 76 | + (for $v:ident in ($start:tt..$end:tt) {$($c:tt)*}) => { |
| 77 | + unroll!{ |
| 78 | + for $v in $start..$end {$($c)*} |
| 79 | + } |
| 80 | + }; |
| 81 | +
|
| 82 | + (for $v:ident in $start:tt..$end:tt {$($c:tt)*}) => { |
| 83 | + #[allow(non_upper_case_globals)] |
| 84 | + #[allow(unused_comparisons)] |
| 85 | + { |
| 86 | + unroll!(@$v, 0, $end, { |
| 87 | + if $v >= $start {$($c)*} |
| 88 | + } |
| 89 | + ); |
| 90 | + } |
| 91 | + }; |
| 92 | +
|
| 93 | + (for $v:ident < $max:tt in $start:tt..$end:tt $c:block) => { |
| 94 | + #[allow(non_upper_case_globals)] |
| 95 | + { |
| 96 | + let range = $start..$end; |
| 97 | + assert!( |
| 98 | + $max >= range.end, |
| 99 | + "`{}` out of range `{:?}`", |
| 100 | + stringify!($max), |
| 101 | + range, |
| 102 | + ); |
| 103 | + unroll!( |
| 104 | + @$v, |
| 105 | + 0, |
| 106 | + $max, |
| 107 | + { |
| 108 | + if $v >= range.start && $v < range.end { |
| 109 | + $c |
| 110 | + } |
| 111 | + } |
| 112 | + ); |
| 113 | + } |
| 114 | + }; |
| 115 | +
|
| 116 | + (for $v:ident in 0..$end:tt {$($statement:tt)*}) => { |
| 117 | + #[allow(non_upper_case_globals)] |
| 118 | + { unroll!(@$v, 0, $end, {$($statement)*}); } |
| 119 | + }; |
| 120 | +
|
| 121 | +"#); |
| 122 | + |
| 123 | + for i in 0..limit + 1 { |
| 124 | + output.push_str(format!(" (@$v:ident, $a:expr, {}, $c:block) => {{\n", i).as_str()); |
| 125 | + |
| 126 | + if i <= LOWER_LIMIT { |
| 127 | + output.push_str(format!(" {{ const $v: usize = $a; $c }}\n").as_str()); |
| 128 | + |
| 129 | + for a in 1..i { |
| 130 | + output.push_str(format!(" {{ const $v: usize = $a + {}; $c }}\n", a).as_str()); |
| 131 | + } |
| 132 | + } else { |
| 133 | + let half = i / 2; |
| 134 | + |
| 135 | + if i % 2 == 0 { |
| 136 | + output.push_str(format!(" unroll!(@$v, $a, {0}, $c);\n", half).as_str()); |
| 137 | + output.push_str(format!(" unroll!(@$v, $a + {0}, {0}, $c);\n", half).as_str()); |
| 138 | + } else { |
| 139 | + if half > 1 { |
| 140 | + output.push_str(format!(" unroll!(@$v, $a, {}, $c);\n", i - 1).as_str()) |
| 141 | + } |
| 142 | + |
| 143 | + output.push_str(format!(" {{ const $v: usize = $a + {}; $c }}\n", i - 1).as_str()); |
| 144 | + } |
| 145 | + } |
| 146 | + |
| 147 | + output.push_str(" };\n\n"); |
| 148 | + } |
| 149 | + |
| 150 | + output.push_str("}\n\n"); |
| 151 | + |
| 152 | + output.push_str(format!(r#" |
| 153 | +#[cfg(all(test, feature = "std"))] |
| 154 | +mod tests {{ |
| 155 | + #[test] |
| 156 | + fn invalid_range() {{ |
| 157 | + let mut a: Vec<usize> = vec![]; |
| 158 | + unroll! {{ |
| 159 | + for i in (5..4) {{ |
| 160 | + a.push(i); |
| 161 | + }} |
| 162 | + }} |
| 163 | + assert_eq!(a, vec![]); |
| 164 | + }} |
| 165 | +
|
| 166 | + #[test] |
| 167 | + fn start_at_one_with_step() {{ |
| 168 | + let mut a: Vec<usize> = vec![]; |
| 169 | + unroll! {{ |
| 170 | + for i in (2..4).step_by(1) {{ |
| 171 | + a.push(i); |
| 172 | + }} |
| 173 | + }} |
| 174 | + assert_eq!(a, vec![2, 3]); |
| 175 | + }} |
| 176 | +
|
| 177 | + #[test] |
| 178 | + fn start_at_one() {{ |
| 179 | + let mut a: Vec<usize> = vec![]; |
| 180 | + unroll! {{ |
| 181 | + for i in 1..4 {{ |
| 182 | + a.push(i); |
| 183 | + }} |
| 184 | + }} |
| 185 | + assert_eq!(a, vec![1, 2, 3]); |
| 186 | + }} |
| 187 | +
|
| 188 | + #[test] |
| 189 | + fn test_all() {{ |
| 190 | + {{ |
| 191 | + let a: Vec<usize> = vec![]; |
| 192 | + unroll! {{ |
| 193 | + for i in 0..0 {{ |
| 194 | + a.push(i); |
| 195 | + }} |
| 196 | + }} |
| 197 | + assert_eq!(a, (0..0).collect::<Vec<usize>>()); |
| 198 | + }} |
| 199 | + {{ |
| 200 | + let mut a: Vec<usize> = vec![]; |
| 201 | + unroll! {{ |
| 202 | + for i in 0..1 {{ |
| 203 | + a.push(i); |
| 204 | + }} |
| 205 | + }} |
| 206 | + assert_eq!(a, (0..1).collect::<Vec<usize>>()); |
| 207 | + }} |
| 208 | + {{ |
| 209 | + let mut a: Vec<usize> = vec![]; |
| 210 | + unroll! {{ |
| 211 | + for i in 0..{0} {{ |
| 212 | + a.push(i); |
| 213 | + }} |
| 214 | + }} |
| 215 | + assert_eq!(a, (0..{0}).collect::<Vec<usize>>()); |
| 216 | + }} |
| 217 | + {{ |
| 218 | + let mut a: Vec<usize> = vec![]; |
| 219 | + let start = {0} / 4; |
| 220 | + let end = start * 3; |
| 221 | + unroll! {{ |
| 222 | + for i < {0} in start..end {{ |
| 223 | + a.push(i); |
| 224 | + }} |
| 225 | + }} |
| 226 | + assert_eq!(a, (start..end).collect::<Vec<usize>>()); |
| 227 | + }} |
| 228 | + {{ |
| 229 | + let mut a: Vec<usize> = vec![]; |
| 230 | + unroll! {{ |
| 231 | + for i in (0..{0}).step_by(2) {{ |
| 232 | + a.push(i); |
| 233 | + }} |
| 234 | + }} |
| 235 | + assert_eq!(a, (0..{0} / 2).map(|x| x * 2).collect::<Vec<usize>>()); |
| 236 | + }} |
| 237 | + {{ |
| 238 | + let mut a: Vec<usize> = vec![]; |
| 239 | + let start = {0} / 4; |
| 240 | + let end = start * 3; |
| 241 | + unroll! {{ |
| 242 | + for i < {0} in (start..end).step_by(2) {{ |
| 243 | + a.push(i); |
| 244 | + }} |
| 245 | + }} |
| 246 | + assert_eq!(a, (start..end).filter(|x| x % 2 == 0).collect::<Vec<usize>>()); |
| 247 | + }} |
| 248 | + }} |
| 249 | +}} |
| 250 | +"#, limit).as_str()); |
| 251 | + |
| 252 | + f.write_all(output.as_bytes()).unwrap(); |
| 253 | +} |
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