1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/pest_meta/src/optimizer/skipper.rs b/vendor/pest_meta/src/optimizer/skipper.rs
new file mode 100644
index 000000000..f55edc06f
--- /dev/null
+++ b/vendor/pest_meta/src/optimizer/skipper.rs
@@ -0,0 +1,57 @@
+// pest. The Elegant Parser
+// Copyright (c) 2018 Dragoș Tiselice
+//
+// Licensed under the Apache License, Version 2.0
+// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
+// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. All files in the project carrying such notice may not be copied,
+// modified, or distributed except according to those terms.
+
+use ast::*;
+
+pub fn skip(rule: Rule) -> Rule {
+    fn populate_choices(expr: Expr, mut choices: Vec<String>) -> Option<Expr> {
+        match expr {
+            Expr::Choice(lhs, rhs) => {
+                if let Expr::Str(string) = *lhs {
+                    choices.push(string);
+                    populate_choices(*rhs, choices)
+                } else {
+                    None
+                }
+            }
+            Expr::Str(string) => {
+                choices.push(string);
+                Some(Expr::Skip(choices))
+            }
+            _ => None,
+        }
+    }
+
+    match rule {
+        Rule { name, ty, expr } => Rule {
+            name,
+            ty,
+            expr: if ty == RuleType::Atomic {
+                expr.map_top_down(|expr| {
+                    // TODO: Use box syntax when it gets stabilized.
+                    if let Expr::Rep(expr) = expr.clone() {
+                        if let Expr::Seq(lhs, rhs) = *expr.clone() {
+                            if let (Expr::NegPred(expr), Expr::Ident(ident)) = (*lhs, *rhs) {
+                                if ident == "ANY" {
+                                    if let Some(expr) = populate_choices(*expr, vec![]) {
+                                        return expr;
+                                    }
+                                }
+                            }
+                        }
+                    };
+
+                    expr
+                })
+            } else {
+                expr
+            },
+        },
+    }
+}