Add std::str::trim/trim_left/trim_right

src/lib/str.rs

@@ -54,6 +54,9 @@ export is_empty;
 export is_not_empty;
 export replace;
 export char_slice;
+export trim_left;
+export trim_right;
+export trim;
 
 native "rust" mod rustrt {
     type sbuf;
@@ -524,6 +527,42 @@ fn char_slice(s: &str, begin: uint, end: uint) -> str {
     from_chars(vec::slice(to_chars(s), begin, end))
 }
 
+fn trim_left(s: &str) -> str {
+    fn count_whities(s: &vec[char]) -> uint {
+        let i = 0u;
+        while i < vec::len(s) {
+            if !char::is_whitespace(s.(i)) {
+                break;
+            }
+            i += 1u;
+        }
+        ret i;
+    }
+    let chars = to_chars(s);
+    let whities = count_whities(chars);
+    ret from_chars(vec::slice(chars, whities, vec::len(chars)));
+}
+
+fn trim_right(s: &str) -> str {
+    fn count_whities(s: &vec[char]) -> uint {
+        let i = vec::len(s);
+        while 0u < i {
+            if !char::is_whitespace(s.(i - 1u)) {
+                break;
+            }
+            i -= 1u;
+        }
+        ret i;
+    }
+    let chars = to_chars(s);
+    let whities = count_whities(chars);
+    ret from_chars(vec::slice(chars, 0u, whities));
+}
+
+fn trim(s: &str) -> str {
+    trim_left(trim_right(s))
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;

src/test/stdtest/str.rs

@@ -162,6 +162,36 @@ fn test_char_slice() {
     assert (str::eq("\u65e5", str::char_slice("\u65e5\u672c", 0u, 1u)));
 }
 
+#[test]
+fn trim_left() {
+    assert str::trim_left("") == "";
+    assert str::trim_left("a") == "a";
+    assert str::trim_left("    ") == "";
+    assert str::trim_left("     blah") == "blah";
+    assert str::trim_left("   \u3000  wut") == "wut";
+    assert str::trim_left("hey ") == "hey ";
+}
+
+#[test]
+fn trim_right() {
+    assert str::trim_right("") == "";
+    assert str::trim_right("a") == "a";
+    assert str::trim_right("    ") == "";
+    assert str::trim_right("blah     ") == "blah";
+    assert str::trim_right("wut   \u3000  ") == "wut";
+    assert str::trim_right(" hey") == " hey";
+}
+
+#[test]
+fn trim() {
+    assert str::trim("") == "";
+    assert str::trim("a") == "a";
+    assert str::trim("    ") == "";
+    assert str::trim("    blah     ") == "blah";
+    assert str::trim("\nwut   \u3000  ") == "wut";
+    assert str::trim(" hey dude ") == "hey dude";
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;