[fractal] fractal-matrix-api: Remove length comparisons to zero

[Alexandre Franke <afranke src gnome org>]

commit 01068ad7521c10d1b7c17b0554d22c330804add9
Author: Zeeshan Ali <zeenix collabora co uk>
Date:   Wed Dec 12 23:05:44 2018 +0100

    fractal-matrix-api: Remove length comparisons to zero
    
    This fixes some errors from clippy about needless length comparison to 0:
    
    ```
    error: length comparison to zero
       --> fractal-matrix-api/src/util.rs:483:27
        |
    483 |     if array.is_none() || array.unwrap().len() == 0 {
        |                           ^^^^^^^^^^^^^^^^^^^^^^^^^ help: using `is_empty` is clearer and more 
explicit: `array.unwrap().is_empty()`
        |
        = note: `-D clippy::len-zero` implied by `-D warnings`
        = help: for further information visit 
https://rust-lang-nursery.github.io/rust-clippy/master/index.html#len_zero
    ```
    
    Related: #370

 fractal-matrix-api/src/backend/room.rs | 2 +-
 fractal-matrix-api/src/util.rs         | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/fractal-matrix-api/src/backend/room.rs b/fractal-matrix-api/src/backend/room.rs
index 6e9d5c1..09f8898 100644
--- a/fractal-matrix-api/src/backend/room.rs
+++ b/fractal-matrix-api/src/backend/room.rs
@@ -206,7 +206,7 @@ fn parse_context(
                 ms.push(m);
             }
 
-            if ms.len() == 0 && id.is_some() {
+            if ms.is_empty() && id.is_some() {
                 // there's no messages so we'll try with a bigger context
                 if let Err(err) =
                     parse_context(tx.clone(), tk, baseu, roomid, &id.unwrap(), limit * 2)
diff --git a/fractal-matrix-api/src/util.rs b/fractal-matrix-api/src/util.rs
index f8f616d..7ccfaa5 100644
--- a/fractal-matrix-api/src/util.rs
+++ b/fractal-matrix-api/src/util.rs
@@ -471,7 +471,7 @@ pub fn get_room_media_list(
     let r = json_q("get", &url, &json!(null), globals::TIMEOUT)?;
     let array = r["chunk"].as_array();
     let prev_batch = r["end"].to_string().trim_matches('"').to_string();
-    if array.is_none() || array.unwrap().len() == 0 {
+    if array.is_none() || array.unwrap().is_empty() {
         return Ok((vec![], prev_batch));
     }
 
@@ -814,7 +814,7 @@ pub fn fill_room_gap(
     nend = String::from(r["end"].as_str().unwrap_or(""));
 
     let array = r["chunk"].as_array();
-    if array.is_none() || array.unwrap().len() == 0 {
+    if array.is_none() || array.unwrap().is_empty() {
         return Ok(ms);
     }
 
@@ -836,7 +836,7 @@ pub fn build_url(base: &Url, path: &str, params: &[(&str, String)]) -> Result<Ur
 
     {
         // If len was 0 `?` would be appended without being needed.
-        if params.len() >= 1 {
+        if !params.is_empty() {
             let mut query = url.query_pairs_mut();
             query.clear();
             for (k, v) in params {