cfg_expr/expr.rs
1pub mod lexer;
2mod parser;
3
4use smallvec::SmallVec;
5use std::ops::Range;
6
7/// A predicate function, used to combine 1 or more predicates
8/// into a single value
9#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
10pub enum Func {
11 /// `not()` with a configuration predicate. It is true if its predicate
12 /// is false and false if its predicate is true.
13 Not,
14 /// `all()` with a comma separated list of configuration predicates. It
15 /// is false if at least one predicate is false. If there are no predicates,
16 /// it is true.
17 ///
18 /// The associated `usize` is the number of predicates inside the `all()`.
19 All(usize),
20 /// `any()` with a comma separated list of configuration predicates. It
21 /// is true if at least one predicate is true. If there are no predicates,
22 /// it is false.
23 ///
24 /// The associated `usize` is the number of predicates inside the `any()`.
25 Any(usize),
26}
27
28use crate::targets as targ;
29
30/// All predicates that pertains to a target, except for `target_feature`
31#[derive(Clone, PartialEq, Eq, Debug)]
32pub enum TargetPredicate {
33 /// [target_abi](https://github.com/rust-lang/rust/issues/80970)
34 Abi(targ::Abi),
35 /// [target_arch](https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch)
36 Arch(targ::Arch),
37 /// [target_endian](https://doc.rust-lang.org/reference/conditional-compilation.html#target_endian)
38 Endian(targ::Endian),
39 /// [target_env](https://doc.rust-lang.org/reference/conditional-compilation.html#target_env)
40 Env(targ::Env),
41 /// [target_family](https://doc.rust-lang.org/reference/conditional-compilation.html#target_family)
42 /// This also applies to the bare [`unix` and `windows`](https://doc.rust-lang.org/reference/conditional-compilation.html#unix-and-windows)
43 /// predicates.
44 Family(targ::Family),
45 /// [target_has_atomic](https://doc.rust-lang.org/reference/conditional-compilation.html#target_has_atomic).
46 HasAtomic(targ::HasAtomic),
47 /// [target_os](https://doc.rust-lang.org/reference/conditional-compilation.html#target_os)
48 Os(targ::Os),
49 /// [panic](https://doc.rust-lang.org/reference/conditional-compilation.html#panic)
50 Panic(targ::Panic),
51 /// [target_pointer_width](https://doc.rust-lang.org/reference/conditional-compilation.html#target_pointer_width)
52 PointerWidth(u8),
53 /// [target_vendor](https://doc.rust-lang.org/reference/conditional-compilation.html#target_vendor)
54 Vendor(targ::Vendor),
55}
56
57pub trait TargetMatcher {
58 fn matches(&self, tp: &TargetPredicate) -> bool;
59}
60
61impl TargetMatcher for targ::TargetInfo {
62 fn matches(&self, tp: &TargetPredicate) -> bool {
63 use TargetPredicate::{
64 Abi, Arch, Endian, Env, Family, HasAtomic, Os, Panic, PointerWidth, Vendor,
65 };
66
67 match tp {
68 // The ABI is allowed to be an empty string
69 Abi(abi) => match &self.abi {
70 Some(a) => abi == a,
71 None => abi.0.is_empty(),
72 },
73 Arch(a) => a == &self.arch,
74 Endian(end) => *end == self.endian,
75 // The environment is allowed to be an empty string
76 Env(env) => match &self.env {
77 Some(e) => env == e,
78 None => env.0.is_empty(),
79 },
80 Family(fam) => self.families.contains(fam),
81 HasAtomic(has_atomic) => self.has_atomics.contains(*has_atomic),
82 Os(os) => match &self.os {
83 Some(self_os) => os == self_os,
84 // os = "none" means it should be matched against None. Note that this is different
85 // from "env" above.
86 None => os.as_str() == "none",
87 },
88 PointerWidth(w) => *w == self.pointer_width,
89 Vendor(ven) => match &self.vendor {
90 Some(v) => ven == v,
91 None => ven == &targ::Vendor::unknown,
92 },
93 Panic(panic) => &self.panic == panic,
94 }
95 }
96}
97
98#[cfg(feature = "targets")]
99impl TargetMatcher for target_lexicon::Triple {
100 #[allow(clippy::cognitive_complexity)]
101 #[allow(clippy::match_same_arms)]
102 fn matches(&self, tp: &TargetPredicate) -> bool {
103 use TargetPredicate::{
104 Abi, Arch, Endian, Env, Family, HasAtomic, Os, Panic, PointerWidth, Vendor,
105 };
106 use target_lexicon::{
107 self as tl, Architecture as arch, ArmArchitecture, Endianness as endian,
108 Environment as env, Mips32Architecture as mips32, Mips64Architecture as mips64,
109 OperatingSystem as os,
110 };
111
112 const NUTTX: tl::Vendor = tl::Vendor::Custom(tl::CustomVendor::Static("nuttx"));
113 const RTEMS: tl::Vendor = tl::Vendor::Custom(tl::CustomVendor::Static("rtems"));
114 const WALI: tl::Vendor = tl::Vendor::Custom(tl::CustomVendor::Static("wali"));
115 const WASIP3: tl::Vendor = tl::Vendor::Custom(tl::CustomVendor::Static("wasip3"));
116 const OE: tl::Vendor = tl::Vendor::Custom(tl::CustomVendor::Static("oe"));
117
118 match tp {
119 Abi(_) => {
120 // `target_abi` is unstable. Assume false for this.
121 false
122 }
123 Arch(arch) => {
124 if arch == &targ::Arch::x86 {
125 matches!(self.architecture, arch::X86_32(_))
126 } else if arch == &targ::Arch::wasm32 {
127 self.architecture == arch::Wasm32 || self.architecture == arch::Asmjs
128 } else if arch == &targ::Arch::arm {
129 matches!(self.architecture, arch::Arm(_))
130 } else if arch == &targ::Arch::bpf {
131 self.architecture == arch::Bpfeb || self.architecture == arch::Bpfel
132 } else if arch == &targ::Arch::x86_64 {
133 self.architecture == arch::X86_64 || self.architecture == arch::X86_64h
134 } else if arch == &targ::Arch::mips32r6 {
135 matches!(
136 self.architecture,
137 arch::Mips32(mips32::Mipsisa32r6 | mips32::Mipsisa32r6el)
138 )
139 } else if arch == &targ::Arch::mips64r6 {
140 matches!(
141 self.architecture,
142 arch::Mips64(mips64::Mipsisa64r6 | mips64::Mipsisa64r6el)
143 )
144 } else if arch == &targ::Arch::amdgpu {
145 self.architecture == arch::AmdGcn
146 } else {
147 match arch.0.parse::<arch>() {
148 Ok(a) => match (self.architecture, a) {
149 (arch::Aarch64(_), arch::Aarch64(_))
150 | (arch::Mips32(_), arch::Mips32(_))
151 | (arch::Mips64(_), arch::Mips64(_))
152 | (arch::Powerpc64le, arch::Powerpc64)
153 | (arch::Riscv32(_), arch::Riscv32(_))
154 | (arch::Riscv64(_), arch::Riscv64(_))
155 | (arch::Sparcv9, arch::Sparc64) => true,
156 (a, b) => a == b,
157 },
158 Err(_) => false,
159 }
160 }
161 }
162 Endian(end) => match self.architecture.endianness() {
163 Ok(endian) => matches!(
164 (end, endian),
165 (crate::targets::Endian::little, endian::Little)
166 | (crate::targets::Endian::big, endian::Big)
167 ),
168
169 Err(_) => false,
170 },
171 Env(env) => {
172 // The environment is implied by some operating systems
173 match self.operating_system {
174 os::Redox => env == &targ::Env::relibc,
175 os::VxWorks => env == &targ::Env::gnu,
176 os::Freebsd => env.0.is_empty(),
177 os::Netbsd => match self.architecture {
178 arch::Arm(ArmArchitecture::Armv6 | ArmArchitecture::Armv7) => {
179 env.0.is_empty()
180 }
181 _ => env.0.is_empty(),
182 },
183 os::None_ | os::Cloudabi | os::Hermit => match self.environment {
184 env::LinuxKernel => env == &targ::Env::gnu,
185 _ => env.0.is_empty(),
186 },
187 os::IOS(_) | os::TvOS(_) => match self.environment {
188 env::LinuxKernel => env == &targ::Env::gnu,
189 env::Macabi => env == &targ::Env::macabi,
190 env::Sim => env == &targ::Env::sim,
191 env::Unknown => env.0.is_empty() || env == &targ::Env::sim,
192 _ => env.0.is_empty(),
193 },
194 os::WasiP1 => env == &targ::Env::p1,
195 os::WasiP2 => env == &targ::Env::p2,
196 os::Wasi => env.0.is_empty() || env == &targ::Env::p1,
197 _ => {
198 if env.0.is_empty() {
199 matches!(
200 self.environment,
201 env::Unknown
202 | env::Android
203 | env::Softfloat
204 | env::Androideabi
205 | env::Eabi
206 | env::Eabihf
207 | env::Sim
208 | env::None
209 )
210 } else if env == &targ::Env::p3 {
211 self.vendor == WASIP3
212 } else {
213 match env.0.parse::<env>() {
214 Ok(e) => {
215 // Rustc shortens multiple "gnu*" environments to just "gnu"
216 if env == &targ::Env::gnu {
217 match self.environment {
218 env::Gnu
219 | env::Gnuabi64
220 | env::Gnueabi
221 | env::Gnuspe
222 | env::Gnux32
223 | env::GnuIlp32
224 | env::Gnueabihf
225 | env::GnuLlvm => true,
226 // Rust 1.49.0 changed all android targets to have the
227 // gnu environment
228 env::Android | env::Androideabi
229 if self.operating_system == os::Linux =>
230 {
231 true
232 }
233 env::Kernel => self.operating_system == os::Linux,
234 _ => self.architecture == arch::Avr,
235 }
236 } else if env == &targ::Env::musl {
237 matches!(
238 self.environment,
239 env::Musl
240 | env::Musleabi
241 | env::Musleabihf
242 | env::Muslabi64
243 )
244 } else if env == &targ::Env::uclibc {
245 matches!(
246 self.environment,
247 env::Uclibc | env::Uclibceabi | env::Uclibceabihf
248 )
249 } else if env == &targ::Env::newlib {
250 matches!(self.operating_system, os::Horizon | os::Espidf)
251 || self.vendor == RTEMS
252 } else {
253 self.environment == e
254 }
255 }
256 Err(_) => false,
257 }
258 }
259 }
260 }
261 }
262 Family(fam) => {
263 match self.operating_system {
264 os::AmdHsa
265 | os::Bitrig
266 | os::Cloudabi
267 | os::Cuda
268 | os::Hermit
269 | os::Nebulet
270 | os::None_
271 | os::Uefi => false,
272 os::Aix
273 | os::Darwin(_)
274 | os::Dragonfly
275 | os::Espidf
276 | os::Freebsd
277 | os::Fuchsia
278 | os::Haiku
279 | os::Hurd
280 | os::Illumos
281 | os::IOS(_)
282 | os::L4re
283 | os::MacOSX { .. }
284 | os::Horizon
285 | os::Netbsd
286 | os::Openbsd
287 | os::Redox
288 | os::Solaris
289 | os::TvOS(_)
290 | os::VisionOS(_)
291 | os::VxWorks
292 | os::WatchOS(_) => fam == &crate::targets::Family::unix,
293 os::Emscripten => {
294 match self.architecture {
295 // asmjs, wasm32 and wasm64 are part of both the wasm and unix families
296 arch::Asmjs | arch::Wasm32 => {
297 fam == &crate::targets::Family::wasm
298 || fam == &crate::targets::Family::unix
299 }
300 _ => false,
301 }
302 }
303 os::Unknown if self.vendor == NUTTX || self.vendor == RTEMS => {
304 fam == &crate::targets::Family::unix
305 }
306 os::Unknown => {
307 // asmjs, wasm32 and wasm64 are part of the wasm family.
308 match self.architecture {
309 arch::Asmjs | arch::Wasm32 | arch::Wasm64 => {
310 fam == &crate::targets::Family::wasm
311 }
312 _ => false,
313 }
314 }
315 os::Linux if self.vendor == WALI => {
316 fam == &crate::targets::Family::wasm || fam == &crate::targets::Family::unix
317 }
318 os::Linux => {
319 // The 'kernel' environment is treated specially as not-unix
320 if self.environment != env::Kernel {
321 fam == &crate::targets::Family::unix
322 } else {
323 false
324 }
325 }
326 os::Wasi | os::WasiP1 | os::WasiP2 => fam == &crate::targets::Family::wasm,
327 os::Windows => fam == &crate::targets::Family::windows,
328 os::Cygwin => fam == &crate::targets::Family::unix,
329 // I really dislike non-exhaustive :(
330 _ => false,
331 }
332 }
333 HasAtomic(_) => {
334 // atomic support depends on both the architecture and the OS. Assume false for
335 // this.
336 false
337 }
338 Os(os) => {
339 if os == &targ::Os::wasi
340 && (matches!(self.operating_system, os::WasiP1 | os::WasiP2)
341 || self.vendor == WASIP3)
342 || (os == &targ::Os::nuttx && self.vendor == NUTTX)
343 || (os == &targ::Os::rtems && self.vendor == RTEMS)
344 {
345 return true;
346 }
347
348 match os.0.parse::<os>() {
349 Ok(o) => match self.environment {
350 env::HermitKernel => os == &targ::Os::hermit,
351 _ => self.operating_system == o,
352 },
353 Err(_) => {
354 // Handle special case for darwin/macos, where the triple is
355 // "darwin", but rustc identifies the OS as "macos"
356 if os == &targ::Os::macos && matches!(self.operating_system, os::Darwin(_))
357 {
358 true
359 } else {
360 // For android, the os is still linux, but the environment is android
361 os == &targ::Os::android
362 && self.operating_system == os::Linux
363 && (self.environment == env::Android
364 || self.environment == env::Androideabi)
365 }
366 }
367 }
368 }
369 Panic(_) => {
370 // panic support depends on the OS. Assume false for this.
371 false
372 }
373 Vendor(ven) => {
374 // Unsure why the OpenEmbedded (oe) targets don't have it as the vendor, but for now the official
375 // rust targets don't
376 if self.vendor == OE && ven == &targ::Vendor::unknown {
377 true
378 } else {
379 match ven.0.parse::<target_lexicon::Vendor>() {
380 Ok(v) => {
381 if self.vendor == v
382 || ((self.vendor == NUTTX
383 || self.vendor == RTEMS
384 || self.vendor == WALI
385 || self.vendor == WASIP3)
386 && ven == &targ::Vendor::unknown)
387 {
388 true
389 } else if let tl::Vendor::Custom(custom) = &self.vendor {
390 matches!(custom.as_str(), "esp" | "esp32" | "esp32s2" | "esp32s3")
391 && (v == tl::Vendor::Espressif || v == tl::Vendor::Unknown)
392 } else {
393 false
394 }
395 }
396 Err(_) => false,
397 }
398 }
399 }
400 PointerWidth(pw) => {
401 // The gnux32 environment is a special case, where it has an
402 // x86_64 architecture, but a 32-bit pointer width
403 if !matches!(self.environment, env::Gnux32 | env::GnuIlp32) {
404 *pw == match self.pointer_width() {
405 Ok(pw) => pw.bits(),
406 Err(_) => return false,
407 }
408 } else {
409 *pw == 32
410 }
411 }
412 }
413 }
414}
415
416impl TargetPredicate {
417 /// Returns true of the predicate matches the specified target
418 ///
419 /// Note that when matching against a [`target_lexicon::Triple`], the
420 /// `has_target_atomic` and `panic` predicates will _always_ return `false`.
421 ///
422 /// ```
423 /// use cfg_expr::{targets::*, expr::TargetPredicate as tp};
424 /// let win = get_builtin_target_by_triple("x86_64-pc-windows-msvc").unwrap();
425 ///
426 /// assert!(
427 /// tp::Arch(Arch::x86_64).matches(win) &&
428 /// tp::Endian(Endian::little).matches(win) &&
429 /// tp::Env(Env::msvc).matches(win) &&
430 /// tp::Family(Family::windows).matches(win) &&
431 /// tp::Os(Os::windows).matches(win) &&
432 /// tp::PointerWidth(64).matches(win) &&
433 /// tp::Vendor(Vendor::pc).matches(win)
434 /// );
435 /// ```
436 pub fn matches<T>(&self, target: &T) -> bool
437 where
438 T: TargetMatcher,
439 {
440 target.matches(self)
441 }
442}
443
444#[derive(Clone, Debug)]
445pub(crate) enum Which {
446 Abi,
447 Arch,
448 Endian(targ::Endian),
449 Env,
450 Family,
451 Os,
452 HasAtomic(targ::HasAtomic),
453 Panic,
454 PointerWidth(u8),
455 Vendor,
456}
457
458#[derive(Clone, Debug)]
459pub(crate) struct InnerTarget {
460 which: Which,
461 span: Option<Range<usize>>,
462}
463
464/// A single predicate in a `cfg()` expression
465#[derive(Debug, PartialEq, Eq)]
466pub enum Predicate<'a> {
467 /// A target predicate, with the `target_` prefix
468 Target(TargetPredicate),
469 /// Whether rustc's test harness is [enabled](https://doc.rust-lang.org/reference/conditional-compilation.html#test)
470 Test,
471 /// [Enabled](https://doc.rust-lang.org/reference/conditional-compilation.html#debug_assertions)
472 /// when compiling without optimizations.
473 DebugAssertions,
474 /// [Enabled](https://doc.rust-lang.org/reference/conditional-compilation.html#proc_macro) for
475 /// crates of the `proc_macro` type.
476 ProcMacro,
477 /// A [`feature = "<name>"`](https://doc.rust-lang.org/nightly/cargo/reference/features.html)
478 Feature(&'a str),
479 /// [target_feature](https://doc.rust-lang.org/reference/conditional-compilation.html#target_feature)
480 TargetFeature(&'a str),
481 /// A generic bare predicate key that doesn't match one of the known options, eg `cfg(bare)`
482 Flag(&'a str),
483 /// A generic key = "value" predicate that doesn't match one of the known options, eg `cfg(foo = "bar")`
484 KeyValue { key: &'a str, val: &'a str },
485}
486
487#[derive(Clone, Debug)]
488pub(crate) enum InnerPredicate {
489 Target(InnerTarget),
490 Test,
491 DebugAssertions,
492 ProcMacro,
493 Feature(Range<usize>),
494 TargetFeature(Range<usize>),
495 Other {
496 identifier: Range<usize>,
497 value: Option<Range<usize>>,
498 },
499}
500
501impl InnerPredicate {
502 fn to_pred<'a>(&self, s: &'a str) -> Predicate<'a> {
503 use InnerPredicate as IP;
504 use Predicate::{
505 DebugAssertions, Feature, Flag, KeyValue, ProcMacro, Target, TargetFeature, Test,
506 };
507
508 match self {
509 IP::Target(it) => match &it.which {
510 Which::Abi => Target(TargetPredicate::Abi(targ::Abi::new(
511 s[it.span.clone().unwrap()].to_owned(),
512 ))),
513 Which::Arch => Target(TargetPredicate::Arch(targ::Arch::new(
514 s[it.span.clone().unwrap()].to_owned(),
515 ))),
516 Which::Os => Target(TargetPredicate::Os(targ::Os::new(
517 s[it.span.clone().unwrap()].to_owned(),
518 ))),
519 Which::Vendor => Target(TargetPredicate::Vendor(targ::Vendor::new(
520 s[it.span.clone().unwrap()].to_owned(),
521 ))),
522 Which::Env => Target(TargetPredicate::Env(targ::Env::new(
523 s[it.span.clone().unwrap()].to_owned(),
524 ))),
525 Which::Family => Target(TargetPredicate::Family(targ::Family::new(
526 s[it.span.clone().unwrap()].to_owned(),
527 ))),
528 Which::Endian(end) => Target(TargetPredicate::Endian(*end)),
529 Which::HasAtomic(has_atomic) => Target(TargetPredicate::HasAtomic(*has_atomic)),
530 Which::Panic => Target(TargetPredicate::Panic(targ::Panic::new(
531 s[it.span.clone().unwrap()].to_owned(),
532 ))),
533 Which::PointerWidth(pw) => Target(TargetPredicate::PointerWidth(*pw)),
534 },
535 IP::Test => Test,
536 IP::DebugAssertions => DebugAssertions,
537 IP::ProcMacro => ProcMacro,
538 IP::Feature(rng) => Feature(&s[rng.clone()]),
539 IP::TargetFeature(rng) => TargetFeature(&s[rng.clone()]),
540 IP::Other { identifier, value } => match value {
541 Some(vs) => KeyValue {
542 key: &s[identifier.clone()],
543 val: &s[vs.clone()],
544 },
545 None => Flag(&s[identifier.clone()]),
546 },
547 }
548 }
549}
550
551#[derive(Clone, Debug)]
552pub(crate) enum ExprNode {
553 Fn(Func),
554 Predicate(InnerPredicate),
555}
556
557/// A parsed `cfg()` expression that can evaluated
558#[derive(Clone, Debug)]
559pub struct Expression {
560 pub(crate) expr: SmallVec<[ExprNode; 5]>,
561 // We keep the original string around for providing the arbitrary
562 // strings that can make up an expression
563 pub(crate) original: String,
564}
565
566impl Expression {
567 /// An iterator over each predicate in the expression
568 pub fn predicates(&self) -> impl Iterator<Item = Predicate<'_>> {
569 self.expr.iter().filter_map(move |item| match item {
570 ExprNode::Predicate(pred) => {
571 let pred = pred.clone().to_pred(&self.original);
572 Some(pred)
573 }
574 ExprNode::Fn(_) => None,
575 })
576 }
577
578 /// Evaluates the expression, using the provided closure to determine the value of
579 /// each predicate, which are then combined into a final result depending on the
580 /// functions `not()`, `all()`, or `any()` in the expression.
581 ///
582 /// `eval_predicate` typically returns `bool`, but may return any type that implements
583 /// the `Logic` trait.
584 ///
585 /// ## Examples
586 ///
587 /// ```
588 /// use cfg_expr::{targets::*, Expression, Predicate};
589 ///
590 /// let linux_musl = get_builtin_target_by_triple("x86_64-unknown-linux-musl").unwrap();
591 ///
592 /// let expr = Expression::parse(r#"all(not(windows), target_env = "musl", any(target_arch = "x86", target_arch = "x86_64"))"#).unwrap();
593 ///
594 /// assert!(expr.eval(|pred| {
595 /// match pred {
596 /// Predicate::Target(tp) => tp.matches(linux_musl),
597 /// _ => false,
598 /// }
599 /// }));
600 /// ```
601 ///
602 /// Returning `Option<bool>`, where `None` indicates the result is unknown:
603 ///
604 /// ```
605 /// use cfg_expr::{targets::*, Expression, Predicate};
606 ///
607 /// let expr = Expression::parse(r#"any(target_feature = "sse2", target_env = "musl")"#).unwrap();
608 ///
609 /// let linux_gnu = get_builtin_target_by_triple("x86_64-unknown-linux-gnu").unwrap();
610 /// let linux_musl = get_builtin_target_by_triple("x86_64-unknown-linux-musl").unwrap();
611 ///
612 /// fn eval(expr: &Expression, target: &TargetInfo) -> Option<bool> {
613 /// expr.eval(|pred| {
614 /// match pred {
615 /// Predicate::Target(tp) => Some(tp.matches(target)),
616 /// Predicate::TargetFeature(_) => None,
617 /// _ => panic!("unexpected predicate"),
618 /// }
619 /// })
620 /// }
621 ///
622 /// // Whether the target feature is present is unknown, so the whole expression evaluates to
623 /// // None (unknown).
624 /// assert_eq!(eval(&expr, linux_gnu), None);
625 ///
626 /// // Whether the target feature is present is irrelevant for musl, since the any() always
627 /// // evaluates to true.
628 /// assert_eq!(eval(&expr, linux_musl), Some(true));
629 /// ```
630 pub fn eval<EP, T>(&self, mut eval_predicate: EP) -> T
631 where
632 EP: FnMut(&Predicate<'_>) -> T,
633 T: Logic + std::fmt::Debug,
634 {
635 let mut result_stack = SmallVec::<[T; 8]>::new();
636
637 // We store the expression as postfix, so just evaluate each component
638 // requirement in the order it comes, and then combining the previous
639 // results according to each operator as it comes
640 for node in self.expr.iter() {
641 match node {
642 ExprNode::Predicate(pred) => {
643 let pred = pred.to_pred(&self.original);
644
645 result_stack.push(eval_predicate(&pred));
646 }
647 ExprNode::Fn(Func::All(count)) => {
648 // all() with a comma separated list of configuration predicates.
649 let mut result = T::top();
650
651 for _ in 0..*count {
652 let r = result_stack.pop().unwrap();
653 result = result.and(r);
654 }
655
656 result_stack.push(result);
657 }
658 ExprNode::Fn(Func::Any(count)) => {
659 // any() with a comma separated list of configuration predicates.
660 let mut result = T::bottom();
661
662 for _ in 0..*count {
663 let r = result_stack.pop().unwrap();
664 result = result.or(r);
665 }
666
667 result_stack.push(result);
668 }
669 ExprNode::Fn(Func::Not) => {
670 // not() with a configuration predicate.
671 // It is true if its predicate is false
672 // and false if its predicate is true.
673 let r = result_stack.pop().unwrap();
674 result_stack.push(r.not());
675 }
676 }
677 }
678
679 result_stack.pop().unwrap()
680 }
681
682 /// The original string which has been parsed to produce this [`Expression`].
683 ///
684 /// ```
685 /// use cfg_expr::Expression;
686 ///
687 /// assert_eq!(
688 /// Expression::parse("any()").unwrap().original(),
689 /// "any()"
690 /// );
691 /// ```
692 #[inline]
693 pub fn original(&self) -> &str {
694 &self.original
695 }
696}
697
698/// [`PartialEq`] will do a **syntactical** comparison, so will just check if both
699/// expressions have been parsed from the same string, **not** if they are semantically
700/// equivalent.
701///
702/// ```
703/// use cfg_expr::Expression;
704///
705/// assert_eq!(
706/// Expression::parse("any()").unwrap(),
707/// Expression::parse("any()").unwrap()
708/// );
709/// assert_ne!(
710/// Expression::parse("any()").unwrap(),
711/// Expression::parse("unix").unwrap()
712/// );
713/// ```
714impl PartialEq for Expression {
715 fn eq(&self, other: &Self) -> bool {
716 self.original.eq(&other.original)
717 }
718}
719
720impl std::str::FromStr for Expression {
721 type Err = crate::error::ParseError;
722
723 fn from_str(s: &str) -> Result<Self, Self::Err> {
724 Expression::parse(s)
725 }
726}
727
728impl std::fmt::Display for Expression {
729 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
730 f.write_str(&self.original)
731 }
732}
733
734/// A propositional logic used to evaluate `Expression` instances.
735///
736/// An `Expression` consists of some predicates and the `any`, `all` and `not` operators. An
737/// implementation of `Logic` defines how the `any`, `all` and `not` operators should be evaluated.
738pub trait Logic {
739 /// The result of an `all` operation with no operands, akin to Boolean `true`.
740 fn top() -> Self;
741
742 /// The result of an `any` operation with no operands, akin to Boolean `false`.
743 fn bottom() -> Self;
744
745 /// `AND`, which corresponds to the `all` operator.
746 fn and(self, other: Self) -> Self;
747
748 /// `OR`, which corresponds to the `any` operator.
749 fn or(self, other: Self) -> Self;
750
751 /// `NOT`, which corresponds to the `not` operator.
752 fn not(self) -> Self;
753}
754
755/// A boolean logic.
756impl Logic for bool {
757 #[inline]
758 fn top() -> Self {
759 true
760 }
761
762 #[inline]
763 fn bottom() -> Self {
764 false
765 }
766
767 #[inline]
768 fn and(self, other: Self) -> Self {
769 self && other
770 }
771
772 #[inline]
773 fn or(self, other: Self) -> Self {
774 self || other
775 }
776
777 #[inline]
778 fn not(self) -> Self {
779 !self
780 }
781}
782
783/// A three-valued logic -- `None` stands for the value being unknown.
784///
785/// The truth tables for this logic are described on
786/// [Wikipedia](https://en.wikipedia.org/wiki/Three-valued_logic#Kleene_and_Priest_logics).
787impl Logic for Option<bool> {
788 #[inline]
789 fn top() -> Self {
790 Some(true)
791 }
792
793 #[inline]
794 fn bottom() -> Self {
795 Some(false)
796 }
797
798 #[inline]
799 fn and(self, other: Self) -> Self {
800 match (self, other) {
801 // If either is false, the expression is false.
802 (Some(false), _) | (_, Some(false)) => Some(false),
803 // If both are true, the expression is true.
804 (Some(true), Some(true)) => Some(true),
805 // One or both are unknown -- the result is unknown.
806 _ => None,
807 }
808 }
809
810 #[inline]
811 fn or(self, other: Self) -> Self {
812 match (self, other) {
813 // If either is true, the expression is true.
814 (Some(true), _) | (_, Some(true)) => Some(true),
815 // If both are false, the expression is false.
816 (Some(false), Some(false)) => Some(false),
817 // One or both are unknown -- the result is unknown.
818 _ => None,
819 }
820 }
821
822 #[inline]
823 fn not(self) -> Self {
824 self.map(|v| !v)
825 }
826}