Implement position structs

src/lib.rs

@@ -0,0 +1,3 @@
+mod pos;
+
+pub use pos::*;

src/pos.rs

@@ -0,0 +1,52 @@
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct LinePos {
+    index: usize,
+    lineno: usize,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct CharPos {
+    line: LinePos,
+    col: usize,
+}
+
+impl LinePos {
+    pub fn new(index: usize, lineno: usize) -> Self {
+        assert!(lineno >= 1);
+        Self { index, lineno }
+    }
+
+    pub fn index(&self) -> usize {
+        self.index
+    }
+
+    pub fn lineno(&self) -> usize {
+        self.lineno
+    }
+}
+
+impl CharPos {
+    pub fn new(index: usize, lineno: usize, col: usize) -> Self {
+        assert!(col >= 1);
+        Self {
+            line: LinePos::new(index, lineno),
+            col,
+        }
+    }
+
+    pub fn line(&self) -> LinePos {
+        self.line
+    }
+
+    pub fn index(&self) -> usize {
+        self.line.index
+    }
+
+    pub fn lineno(&self) -> usize {
+        self.line.lineno
+    }
+
+    pub fn col(&self) -> usize {
+        self.col
+    }
+}