1 files changed, 51 insertions, 14 deletions

diff --git a/src/info.rs b/src/info.rs
index 5504de1..e4aa546 100644
--- a/src/info.rs
+++ b/src/info.rs
@@ -26,14 +26,33 @@ pub fn init () {
 
 macro_rules! def_escape(
     ($name:ident -> $escape:expr) => (
-        pub fn $name () -> ~str { escape($escape) }
+        pub fn $name () -> ~str {
+            let attr = $escape;
+            match escape(attr) {
+                Some(e) => e,
+                None    => fail!(fmt!("%s is not supported on this terminal",
+                                      attr)),
+            }
+        }
     );
     ($name:ident -> $escape:expr, $ty1:ident) => (
-        pub fn $name (p1: $ty1) -> ~str { escape1($escape, p1 as int) }
+        pub fn $name (p1: $ty1) -> ~str {
+            let attr = $escape;
+            match escape1(attr, p1 as int) {
+                Some(e) => e,
+                None    => fail!(fmt!("%s is not supported on this terminal",
+                                      attr)),
+            }
+        }
     );
     ($name:ident -> $escape:expr, $ty1:ident, $ty2:ident) => (
         pub fn $name (p1: $ty1, p2: $ty2) -> ~str {
-            escape2($escape, p1 as int, p2 as int)
+            let attr = $escape;
+            match escape2(attr, p1 as int, p2 as int) {
+                Some(e) => e,
+                None    => fail!(fmt!("%s is not supported on this terminal",
+                                      attr)),
+            }
         }
     );
 )
@@ -131,14 +150,24 @@ def_escape!(key_f12         -> "kf12")
 
 /// The terminal escape generated by the F<`n`> key.
 pub fn key_f (n: uint) -> ~str {
-    escape(fmt!("kf%?", n))
+    let attr = fmt!("kf%?", n);
+    match escape(attr) {
+        Some(e) => e,
+        None    => fail!(fmt!("%s is not supported on this terminal", attr)),
+    }
 }
 
 /// The terminal escape corresponding to the `name` terminfo capability.
-pub fn escape (name: &str) -> ~str {
+pub fn escape (name: &str) -> Option<~str> {
     do str::as_c_str(name) |c_name| {
         unsafe {
-            str::raw::from_c_str(tigetstr(c_name))
+            let e = tigetstr(c_name);
+            if e == ptr::null() {
+                None
+            }
+            else {
+                Some(str::raw::from_c_str(e))
+            }
         }
     }
 }
@@ -148,10 +177,16 @@ pub fn escape (name: &str) -> ~str {
  *
  * This capability must take one parameter, which should be passed as `p1`.
  */
-pub fn escape1 (name: &str, p1: int) -> ~str {
+pub fn escape1 (name: &str, p1: int) -> Option<~str> {
     do str::as_c_str(name) |c_name| {
         unsafe {
-            str::raw::from_c_str(tiparm1(tigetstr(c_name), p1))
+            let e = tigetstr(c_name);
+            if e == ptr::null() {
+                None
+            }
+            else {
+                Some(str::raw::from_c_str(tiparm1(e, p1)))
+            }
         }
     }
 }
@@ -162,10 +197,16 @@ pub fn escape1 (name: &str, p1: int) -> ~str {
  * This capability must take two parameters, which should be passed as `p1`
  * and `p2`.
  */
-pub fn escape2 (name: &str, p1: int, p2: int) -> ~str {
+pub fn escape2 (name: &str, p1: int, p2: int) -> Option<~str> {
     do str::as_c_str(name) |c_name| {
         unsafe {
-            str::raw::from_c_str(tiparm2(tigetstr(c_name), p1, p2))
+            let e = tigetstr(c_name);
+            if e == ptr::null() {
+                None
+            }
+            else {
+                Some(str::raw::from_c_str(tiparm2(e, p1, p2)))
+            }
         }
     }
 }
@@ -176,10 +217,6 @@ unsafe fn tigetstr (name: *c_char) -> *c_char {
         fail!(fmt!("%s is not a terminal capability",
                    unsafe { str::raw::from_c_str(name) }));
     }
-    else if c_out == ptr::null() {
-        fail!(fmt!("The current terminal doesn't support %s",
-                   unsafe { str::raw::from_c_str(name) }));
-    }
     c_out
 }