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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:06:37 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:06:37 +0000 |
commit | 246f239d9f40f633160f0c18f87a20922d4e77bb (patch) | |
tree | 5a88572663584b3d4d28e5a20e10abab1be40884 /vendor/pest_meta/src/optimizer/factorizer.rs | |
parent | Releasing progress-linux version 1.64.0+dfsg1-1~progress7.99u1. (diff) | |
download | rustc-246f239d9f40f633160f0c18f87a20922d4e77bb.tar.xz rustc-246f239d9f40f633160f0c18f87a20922d4e77bb.zip |
Merging debian version 1.65.0+dfsg1-2.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | vendor/pest_meta/src/optimizer/factorizer.rs | 61 |
1 files changed, 37 insertions, 24 deletions
diff --git a/vendor/pest_meta/src/optimizer/factorizer.rs b/vendor/pest_meta/src/optimizer/factorizer.rs index 236289e14..5481870bf 100644 --- a/vendor/pest_meta/src/optimizer/factorizer.rs +++ b/vendor/pest_meta/src/optimizer/factorizer.rs @@ -7,32 +7,45 @@ // option. All files in the project carrying such notice may not be copied, // modified, or distributed except according to those terms. -use ast::*; +use crate::ast::*; pub fn factor(rule: Rule) -> Rule { - match rule { - Rule { name, ty, expr } => Rule { - name, - ty, - expr: expr.map_top_down(|expr| { - // TODO: Use box syntax when it gets stabilized. - match expr { - Expr::Choice(lhs, rhs) => match (*lhs, *rhs) { - (Expr::Seq(l1, r1), Expr::Seq(l2, r2)) => { - if l1 == l2 { - Expr::Seq(l1, Box::new(Expr::Choice(r1, r2))) - } else { - Expr::Choice( - Box::new(Expr::Seq(l1, r1)), - Box::new(Expr::Seq(l2, r2)), - ) - } + let Rule { name, ty, expr } = rule; + Rule { + name, + ty, + expr: expr.map_top_down(|expr| { + // TODO: Use box syntax when it gets stabilized. + match expr { + Expr::Choice(lhs, rhs) => match (*lhs, *rhs) { + (Expr::Seq(l1, r1), Expr::Seq(l2, r2)) => { + if l1 == l2 { + Expr::Seq(l1, Box::new(Expr::Choice(r1, r2))) + } else { + Expr::Choice(Box::new(Expr::Seq(l1, r1)), Box::new(Expr::Seq(l2, r2))) } - (lhs, rhs) => Expr::Choice(Box::new(lhs), Box::new(rhs)), - }, - expr => expr, - } - }), - }, + } + // Converts `(rule ~ rest) | rule` to `rule ~ rest?`, avoiding trying to match `rule` twice. + (Expr::Seq(l1, l2), r) => { + if *l1 == r { + Expr::Seq(l1, Box::new(Expr::Opt(l2))) + } else { + Expr::Choice(Box::new(Expr::Seq(l1, l2)), Box::new(r)) + } + } + // Converts `rule | (rule ~ rest)` to `rule` since `(rule ~ rest)` + // will never match if `rule` didn't. + (l, Expr::Seq(r1, r2)) => { + if l == *r1 { + l + } else { + Expr::Choice(Box::new(l), Box::new(Expr::Seq(r1, r2))) + } + } + (lhs, rhs) => Expr::Choice(Box::new(lhs), Box::new(rhs)), + }, + expr => expr, + } + }), } } |