A parser and evaluator for Rustcfg() expressions. Builtin targets as of 1.88.0 are supported.

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Usage

use cfg_expr::{targets::get_builtin_target_by_triple,Expression,Predicate};let specific =Expression::parse(r#"all(        target_os = "windows",        target_arch = "x86",        windows,        target_env = "msvc",        target_feature = "fxsr",        target_feature = "sse",        target_feature = "sse2",        target_pointer_width = "32",        target_endian = "little",        not(target_vendor = "uwp"),        feature = "cool_thing",    )"#,).unwrap();// cfg_expr includes a list of every builtin target in rustclet x86_win =get_builtin_target_by_triple("i686-pc-windows-msvc").unwrap();let uwp_win =get_builtin_target_by_triple("i686-uwp-windows-msvc").unwrap();let mac =get_builtin_target_by_triple("x86_64-apple-darwin").unwrap();let avail_target_feats =["fxsr","sse","sse2"];// This will satisfy all requirementsassert!(specific.eval(|pred|{match pred{Predicate::Target(tp) => tp.matches(x86_win),Predicate::TargetFeature(feat) => avail_target_feats.contains(feat),Predicate::Feature(feat) =>*feat =="cool_thing",        _ =>false,}}));// This will *not* satisfy the vendor predicateassert!(!specific.eval(|pred|{match pred{Predicate::Target(tp) => tp.matches(uwp_win),Predicate::TargetFeature(feat) => avail_target_feats.contains(feat),        _ =>false,}}));// This will *not* satisfy the vendor, os, or env predicatesassert!(!specific.eval(|pred|{match pred{Predicate::Target(tp) => tp.matches(mac),Predicate::TargetFeature(feat) => avail_target_feats.contains(feat),        _ =>false,}}));

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