Parser: groundwork

1 files changed, 59 insertions, 0 deletions

diff --git a/src/text.rs b/src/text.rs
index c3ef1ac8e..ee0dc8398 100644
--- a/src/text.rs
+++ b/src/text.rs
@@ -56,4 +56,63 @@ impl ops::SubAssign<TextUnit> for TextUnit {
     fn sub_assign(&mut self, rhs: TextUnit) {
         self.0 -= rhs.0
     }
+}
+
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct TextRange {
+    start: TextUnit,
+    end: TextUnit,
+}
+
+impl fmt::Debug for TextRange {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        <Self as fmt::Display>::fmt(self, f)
+    }
+}
+
+impl fmt::Display for TextRange {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "[{}; {})", self.start(), self.end())
+    }
+}
+
+
+impl TextRange {
+    pub fn empty() -> TextRange {
+        TextRange::from_to(TextUnit::new(0), TextUnit::new(0))
+    }
+
+    pub fn from_to(from: TextUnit, to: TextUnit) -> TextRange {
+        assert!(from <= to, "Invalid text range [{}; {})", from, to);
+        TextRange { start: from, end: to }
+    }
+
+    pub fn from_len(from: TextUnit, len: TextUnit) -> TextRange {
+        TextRange::from_to(from, from + len)
+    }
+
+    pub fn start(&self) -> TextUnit {
+        self.start
+    }
+
+    pub fn end(&self) -> TextUnit {
+        self.end
+    }
+
+    pub fn len(&self) -> TextUnit {
+        self.end - self.start
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.start() == self.end()
+    }
+}
+
+impl ops::Index<TextRange> for str {
+    type Output = str;
+
+    fn index(&self, index: TextRange) -> &str {
+        &self[index.start().0 as usize..index.end().0 as usize]
+    }
 }
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