1 files changed, 45 insertions, 0 deletions
diff --git a/src/util.rs b/src/util.rs
new file mode 100644
index 0000000..5376fa6
--- /dev/null
+++ b/src/util.rs
@@ -0,0 +1,45 @@
+pub fn is_boundary(line: &str, ix: Option<usize>) -> bool {
+    ix.and_then(|v| line.chars().nth(v))
+        .map(|c| c.is_whitespace() || c == '"' || c == '(' || c == ')' || c == '<' || c == '>')
+        .unwrap_or(true)
+}
+
+pub fn find_from(line: &str, ix_start: usize, key: &str) -> Option<usize> {
+    line[ix_start..].find(key).map(|v| ix_start + v)
+}
+
+pub fn find_from_u8(line: &[u8], ix_start: usize, key: &[u8]) -> Option<usize> {
+    assert!(!key.is_empty());
+    assert!(ix_start < line.len());
+    if line.len() < key.len() {
+        return None;
+    }
+    let ix_end = line.len() - key.len();
+    if ix_start <= ix_end {
+        for i in ix_start..ix_end {
+            if line[i] == key[0] {
+                let mut success = true;
+                for j in 1..key.len() {
+                    if line[i + j] != key[j] {
+                        success = false;
+                        break;
+                    }
+                }
+                if success {
+                    return Some(i);
+                }
+            }
+        }
+    }
+    None
+}
+
+#[test]
+fn test_find_from_u8() {
+    assert_eq!(find_from_u8(b"hello world", 0, b"hell"), Some(0));
+    assert_eq!(find_from_u8(b"hello world", 0, b"o"), Some(4));
+    assert_eq!(find_from_u8(b"hello world", 4, b"o"), Some(4));
+    assert_eq!(find_from_u8(b"hello world", 5, b"o"), Some(7));
+    assert_eq!(find_from_u8(b"hello world", 8, b"o"), None);
+    assert_eq!(find_from_u8(b"hello world", 10, b"d"), None);
+}