From 85213a843566b82b05626efd97c48644b04935d2 Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Wed, 27 Apr 2016 01:50:04 -0400
Subject: start implementing cells

---
 src/cell.rs    | 30 ++++++++++++++++++++++++++++++
 src/ffi.rs     |  6 ++++++
 src/lib.rs     |  2 ++
 src/screen.rs  | 12 ++++++++++++
 src/types.rs   |  1 +
 tests/basic.rs | 14 ++++++++++++++
 6 files changed, 65 insertions(+)
 create mode 100644 src/cell.rs

diff --git a/src/cell.rs b/src/cell.rs
new file mode 100644
index 0000000..7590e98
--- /dev/null
+++ b/src/cell.rs
@@ -0,0 +1,30 @@
+use libc;
+use std;
+
+use types;
+
+pub struct Cell(*mut types::CellImpl);
+
+#[repr(C)]
+struct CellPrefix {
+    pub contents: [libc::c_char; 8],
+    pub len: libc::size_t,
+}
+
+impl Cell {
+    pub fn new(cell_impl: *mut types::CellImpl) -> Cell {
+        Cell(cell_impl)
+    }
+
+    pub fn contents(&self) -> &str {
+        let Cell(cell_impl) = *self;
+        let contents: &[u8] = unsafe {
+            let prefix: *mut CellPrefix = std::mem::transmute(cell_impl);
+            std::slice::from_raw_parts(
+                &(*prefix).contents as *const i8 as *const u8,
+                (*prefix).len
+            )
+        };
+        std::str::from_utf8(contents).unwrap()
+    }
+}
diff --git a/src/ffi.rs b/src/ffi.rs
index 1b984b5..e498361 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -32,6 +32,12 @@ extern "C" {
         rows: libc::c_int,
     );
 
+    pub fn vt100_screen_cell_at(
+        screen: *mut types::ScreenImpl,
+        row: libc::c_int,
+        col: libc::c_int,
+    ) -> *mut types::CellImpl;
+
     pub fn vt100_wrapper_rows(screen: *mut types::ScreenImpl) -> libc::c_int;
     pub fn vt100_wrapper_cols(screen: *mut types::ScreenImpl) -> libc::c_int;
 }
diff --git a/src/lib.rs b/src/lib.rs
index 71fc540..aa7d488 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,9 @@
 extern crate libc;
 
+mod cell;
 mod ffi;
 mod screen;
 mod types;
 
 pub use screen::Screen;
+pub use cell::Cell;
diff --git a/src/screen.rs b/src/screen.rs
index da96a6a..d3e026f 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -1,6 +1,7 @@
 use libc;
 use std;
 
+use cell;
 use ffi;
 use types;
 
@@ -91,6 +92,17 @@ impl Screen {
         }.to_vec();
         std::string::String::from_utf8(rust_plaintext).unwrap()
     }
+
+    pub fn cell(&self, row: i32, col: i32) -> Option<cell::Cell> {
+        let Screen(screen_impl) = *self;
+        if row < 0 || row >= self.rows() || col < 0 || col >= self.cols() {
+            return None
+        }
+        let cell_impl = unsafe {
+            ffi::vt100_screen_cell_at(screen_impl, row, col)
+        };
+        Some(cell::Cell::new(cell_impl))
+    }
 }
 
 impl Drop for Screen {
diff --git a/src/types.rs b/src/types.rs
index a5ac590..fca7f97 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,6 +1,7 @@
 use libc;
 
 pub enum ScreenImpl {}
+pub enum CellImpl {}
 
 #[repr(C)]
 pub struct Loc {
diff --git a/tests/basic.rs b/tests/basic.rs
index 7312928..27b688d 100644
--- a/tests/basic.rs
+++ b/tests/basic.rs
@@ -25,4 +25,18 @@ mod tests {
         assert_eq!(screen.rows(), 34);
         assert_eq!(screen.cols(), 8);
     }
+
+    #[test]
+    fn cell_contents() {
+        let mut screen = vt100::Screen::new(24, 80);
+        let input = b"foo\x1b[31m\x1b[32mb\x1b[3;7;42ma\x1b[23mr";
+        screen.process(input);
+        assert_eq!(screen.cell(0, 0).unwrap().contents(), "f");
+        assert_eq!(screen.cell(0, 1).unwrap().contents(), "o");
+        assert_eq!(screen.cell(0, 2).unwrap().contents(), "o");
+        assert_eq!(screen.cell(0, 3).unwrap().contents(), "b");
+        assert_eq!(screen.cell(0, 4).unwrap().contents(), "a");
+        assert_eq!(screen.cell(0, 5).unwrap().contents(), "r");
+        assert_eq!(screen.cell(0, 6).unwrap().contents(), "");
+    }
 }
-- 
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