Auto merge of #23682 - tamird:DRY-is-empty, r=alexcrichton

r? @alexcrichton

Author: bors

src/compiletest/compiletest.rs

@@ -368,7 +368,7 @@ pub fn make_metrics_test_closure(config: &Config, testfile: &Path) -> test::Test
 fn extract_gdb_version(full_version_line: Option<String>) -> Option<String> {
     match full_version_line {
         Some(ref full_version_line)
-          if full_version_line.trim().len() > 0 => {
+          if !full_version_line.trim().is_empty() => {
             let full_version_line = full_version_line.trim();
 
             // used to be a regex "(^|[^0-9])([0-9]\.[0-9])([^0-9]|$)"
@@ -408,7 +408,7 @@ fn extract_lldb_version(full_version_line: Option<String>) -> Option<String> {
 
     match full_version_line {
         Some(ref full_version_line)
-          if full_version_line.trim().len() > 0 => {
+          if !full_version_line.trim().is_empty() => {
             let full_version_line = full_version_line.trim();
 
             for (pos, l) in full_version_line.char_indices() {
@@ -426,7 +426,7 @@ fn extract_lldb_version(full_version_line: Option<String>) -> Option<String> {
                 let vers = full_version_line[pos + 5..].chars().take_while(|c| {
                     c.is_digit(10)
                 }).collect::<String>();
-                if vers.len() > 0 { return Some(vers) }
+                if !vers.is_empty() { return Some(vers) }
             }
             println!("Could not extract LLDB version from line '{}'",
                      full_version_line);

src/compiletest/runtest.rs

@@ -864,7 +864,7 @@ fn check_debugger_output(debugger_run_result: &ProcRes, check_lines: &[String])
                 }
                 first = false;
             }
-            if !failed && rest.len() == 0 {
+            if !failed && rest.is_empty() {
                 i += 1;
             }
             if i == num_check_lines {
@@ -1662,7 +1662,7 @@ fn _arm_push_aux_shared_library(config: &Config, testfile: &Path) {
 // codegen tests (vs. clang)
 
 fn append_suffix_to_stem(p: &Path, suffix: &str) -> PathBuf {
-    if suffix.len() == 0 {
+    if suffix.is_empty() {
         p.to_path_buf()
     } else {
         let mut stem = p.file_stem().unwrap().to_os_string();

src/doc/reference.md

@@ -3788,7 +3788,7 @@ its type parameters are types:
 
 ```ignore
 fn map<A: Clone, B: Clone>(f: |A| -> B, xs: &[A]) -> Vec<B> {
-    if xs.len() == 0 {
+    if xs.is_empty() {
        return vec![];
     }
     let first: B = f(xs[0].clone());

src/libcollections/btree/map.rs

@@ -692,7 +692,7 @@ mod stack {
                         // We've reached the root, so no matter what, we're done. We manually
                         // access the root via the tree itself to avoid creating any dangling
                         // pointers.
-                        if self.map.root.len() == 0 && !self.map.root.is_leaf() {
+                        if self.map.root.is_empty() && !self.map.root.is_leaf() {
                             // We've emptied out the root, so make its only child the new root.
                             // If it's a leaf, we just let it become empty.
                             self.map.depth -= 1;

src/libcollections/btree/node.rs

@@ -585,6 +585,9 @@ impl <K, V> Node<K, V> {
         self._len
     }
 
+    /// Does the node not contain any key-value pairs
+    pub fn is_empty(&self) -> bool { self.len() == 0 }
+
     /// How many key-value pairs the node can fit
     pub fn capacity(&self) -> usize {
         self._capacity
@@ -1097,7 +1100,7 @@ impl<K, V> Node<K, V> {
     /// When a node has no keys or values and only a single edge, extract that edge.
     pub fn hoist_lone_child(&mut self) {
         // Necessary for correctness, but in a private module
-        debug_assert!(self.len() == 0);
+        debug_assert!(self.is_empty());
         debug_assert!(!self.is_leaf());
 
         unsafe {
@@ -1225,7 +1228,7 @@ impl<K, V> Node<K, V> {
     /// because we have one too many, and our parent now has one too few
     fn split(&mut self) -> (K, V, Node<K, V>) {
         // Necessary for correctness, but in a private function
-        debug_assert!(self.len() > 0);
+        debug_assert!(!self.is_empty());
 
         let mut right = if self.is_leaf() {
             Node::new_leaf(self.capacity())

src/libcore/char.rs

@@ -227,7 +227,7 @@ impl CharExt for char {
 #[inline]
 pub fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> Option<usize> {
     // Marked #[inline] to allow llvm optimizing it away
-    if code < MAX_ONE_B && dst.len() >= 1 {
+    if code < MAX_ONE_B && !dst.is_empty() {
         dst[0] = code as u8;
         Some(1)
     } else if code < MAX_TWO_B && dst.len() >= 2 {
@@ -258,7 +258,7 @@ pub fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> Option<usize> {
 #[inline]
 pub fn encode_utf16_raw(mut ch: u32, dst: &mut [u16]) -> Option<usize> {
     // Marked #[inline] to allow llvm optimizing it away
-    if (ch & 0xFFFF) == ch  && dst.len() >= 1 {
+    if (ch & 0xFFFF) == ch && !dst.is_empty() {
         // The BMP falls through (assuming non-surrogate, as it should)
         dst[0] = ch as u16;
         Some(1)

src/libcore/slice.rs

@@ -204,7 +204,7 @@ impl<T> SliceExt for [T] {
 
     #[inline]
     fn first(&self) -> Option<&T> {
-        if self.len() == 0 { None } else { Some(&self[0]) }
+        if self.is_empty() { None } else { Some(&self[0]) }
     }
 
     #[inline]
@@ -217,7 +217,7 @@ impl<T> SliceExt for [T] {
 
     #[inline]
     fn last(&self) -> Option<&T> {
-        if self.len() == 0 { None } else { Some(&self[self.len() - 1]) }
+        if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
     }
 
     #[inline]
@@ -296,7 +296,7 @@ impl<T> SliceExt for [T] {
 
     #[inline]
     fn first_mut(&mut self) -> Option<&mut T> {
-        if self.len() == 0 { None } else { Some(&mut self[0]) }
+        if self.is_empty() { None } else { Some(&mut self[0]) }
     }
 
     #[inline]
@@ -1306,7 +1306,7 @@ impl<'a, T> Iterator for Chunks<'a, T> {
 
     #[inline]
     fn next(&mut self) -> Option<&'a [T]> {
-        if self.v.len() == 0 {
+        if self.v.is_empty() {
             None
         } else {
             let chunksz = cmp::min(self.v.len(), self.size);
@@ -1318,7 +1318,7 @@ impl<'a, T> Iterator for Chunks<'a, T> {
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        if self.v.len() == 0 {
+        if self.v.is_empty() {
             (0, Some(0))
         } else {
             let n = self.v.len() / self.size;
@@ -1333,7 +1333,7 @@ impl<'a, T> Iterator for Chunks<'a, T> {
 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
     #[inline]
     fn next_back(&mut self) -> Option<&'a [T]> {
-        if self.v.len() == 0 {
+        if self.v.is_empty() {
             None
         } else {
             let remainder = self.v.len() % self.size;
@@ -1384,7 +1384,7 @@ impl<'a, T> Iterator for ChunksMut<'a, T> {
 
     #[inline]
     fn next(&mut self) -> Option<&'a mut [T]> {
-        if self.v.len() == 0 {
+        if self.v.is_empty() {
             None
         } else {
             let sz = cmp::min(self.v.len(), self.chunk_size);
@@ -1397,7 +1397,7 @@ impl<'a, T> Iterator for ChunksMut<'a, T> {
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        if self.v.len() == 0 {
+        if self.v.is_empty() {
             (0, Some(0))
         } else {
             let n = self.v.len() / self.chunk_size;
@@ -1412,7 +1412,7 @@ impl<'a, T> Iterator for ChunksMut<'a, T> {
 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
     #[inline]
     fn next_back(&mut self) -> Option<&'a mut [T]> {
-        if self.v.len() == 0 {
+        if self.v.is_empty() {
             None
         } else {
             let remainder = self.v.len() % self.chunk_size;

src/libcore/str/mod.rs

@@ -1119,7 +1119,7 @@ enum OldSearcher {
 impl OldSearcher {
     #[allow(dead_code)]
     fn new(haystack: &[u8], needle: &[u8]) -> OldSearcher {
-        if needle.len() == 0 {
+        if needle.is_empty() {
             // Handle specially
             unimplemented!()
         // FIXME: Tune this.

src/libcore/str/pattern.rs

@@ -457,7 +457,7 @@ fn str_search_step<F, G>(mut m: &mut StrSearcher,
 {
     if m.state.done() {
         SearchStep::Done
-    } else if m.needle.len() == 0 && m.start <= m.end {
+    } else if m.needle.is_empty() && m.start <= m.end {
         // Case for needle == ""
         if let State::Reject(a, b) = m.state.take() {
             SearchStep::Reject(a, b)

src/libfmt_macros/lib.rs

@@ -371,7 +371,7 @@ impl<'a> Parser<'a> {
             None => {
                 let tmp = self.cur.clone();
                 match self.word() {
-                    word if word.len() > 0 => {
+                    word if !word.is_empty() => {
                         if self.consume('$') {
                             CountIsName(word)
                         } else {
@@ -463,7 +463,7 @@ mod tests {
     fn musterr(s: &str) {
         let mut p = Parser::new(s);
         p.next();
-        assert!(p.errors.len() != 0);
+        assert!(!p.errors.is_empty());
     }
 
     #[test]