1 files changed, 154 insertions, 0 deletions
diff --git a/semver-parser/src/recognize.rs b/semver-parser/src/recognize.rs
new file mode 100644
index 0000000..c0dd771
--- /dev/null
+++ b/semver-parser/src/recognize.rs
@@ -0,0 +1,154 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under either of MIT or Apache License, Version 2.0,
+// at your option.
+//
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Simple recognizer combinators.
+
+// This version is similar to a similar one in the "lang" module of
+// xi-editor, but is stripped down to only the needed combinators.
+
+use std::ops;
+
+pub trait Recognize {
+    fn p(&self, s: &[u8]) -> Option<usize>;
+}
+
+impl<F: Fn(&[u8]) -> Option<usize>> Recognize for F {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        self(s)
+    }
+}
+
+pub struct OneByte<F>(pub F);
+
+impl<F: Fn(u8) -> bool> Recognize for OneByte<F> {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        if s.is_empty() || !self.0(s[0]) {
+            None
+        } else {
+            Some(1)
+        }
+    }
+}
+
+impl Recognize for u8 {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        OneByte(|b| b == *self).p(s)
+    }
+}
+
+/// Use Inclusive(a..b) to indicate an inclusive range. When a...b syntax becomes
+/// stable, we can get rid of this and switch to that.
+pub struct Inclusive<T>(pub T);
+
+impl Recognize for Inclusive<ops::Range<u8>> {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        OneByte(|x| x >= self.0.start && x <= self.0.end).p(s)
+    }
+}
+
+impl<'a> Recognize for &'a [u8] {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        let len = self.len();
+        if s.len() >= len && &s[..len] == *self {
+            Some(len)
+        } else {
+            None
+        }
+    }
+}
+
+impl<'a> Recognize for &'a str {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        self.as_bytes().p(s)
+    }
+}
+
+impl<P1: Recognize, P2: Recognize> Recognize for (P1, P2) {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        self.0.p(s).and_then(|len1|
+            self.1.p(&s[len1..]).map(|len2|
+                len1 + len2))
+    }
+}
+
+/// Choice from two heterogeneous alternatives.
+pub struct Alt<P1, P2>(pub P1, pub P2);
+
+impl<P1: Recognize, P2: Recognize> Recognize for Alt<P1, P2> {
+    #[inline(always)]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        self.0.p(s).or_else(|| self.1.p(s))
+    }
+}
+
+/// Choice from a homogenous slice of parsers.
+pub struct OneOf<'a, P: 'a>(pub &'a [P]);
+
+impl<'a, P: Recognize> Recognize for OneOf<'a, P> {
+    #[inline]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        for ref p in self.0 {
+            if let Some(len) = p.p(s) {
+                return Some(len);
+            }
+        }
+        None
+    }
+}
+
+pub struct OneOrMore<P>(pub P);
+
+impl<P: Recognize> Recognize for OneOrMore<P> {
+    #[inline]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        let mut i = 0;
+        let mut count = 0;
+        while let Some(len) = self.0.p(&s[i..]) {
+            i += len;
+            count += 1;
+        }
+        if count >= 1 {
+            Some(i)
+        } else {
+            None
+        }
+    }
+}
+
+pub struct ZeroOrMore<P>(pub P);
+
+impl<P: Recognize> Recognize for ZeroOrMore<P> {
+    #[inline]
+    fn p(&self, s: &[u8]) -> Option<usize> {
+        let mut i = 0;
+        while let Some(len) = self.0.p(&s[i..]) {
+            i += len;
+        }
+        Some(i)
+    }
+}