M4: fetch mode, cleanup and documentation

- --fetch with a Jinja-subset renderer and the shipped templates
- clippy clean, cargo fmt, all tests green
- README status and differential testing instructions

crates/glances-core/src/units.rs

@@ -69,7 +69,22 @@ pub fn auto_unit(number: f64, low_precision: bool, min_symbol: &str, none_symbol
 
 /// Render a progress bar the way the Python `Bar` class does.
 pub fn bar_percent(percent: f64, size: usize, bar_char: &str, display_value: bool) -> String {
-    let size = if display_value { size.saturating_sub(6) } else { size };
+    bar_custom(percent, size, bar_char, " ", display_value)
+}
+
+/// Render a progress bar with custom characters.
+pub fn bar_custom(
+    percent: f64,
+    size: usize,
+    bar_char: &str,
+    empty_char: &str,
+    display_value: bool,
+) -> String {
+    let size = if display_value {
+        size.saturating_sub(6)
+    } else {
+        size
+    };
     let value = percent.clamp(0.0, 100.0);
     let scaled = size as f64 * value / 100.0;
     let whole = scaled.floor() as usize;
@@ -81,14 +96,18 @@ pub fn bar_percent(percent: f64, size: usize, bar_char: &str, display_value: boo
         if (frac * 8.0) as usize >= 5 {
             bar.push_str(bar_char);
         } else {
-            bar.push(' ');
+            bar.push_str(empty_char);
         }
         whole += 1;
     }
-    bar.push_str(&" ".repeat(size.saturating_sub(whole)));
+    bar.push_str(&empty_char.repeat(size.saturating_sub(whole)));
     if display_value {
         if percent >= 100.0 {
-            bar = format!("{bar} {}{:3.0}%", if percent > 100.0 { ">" } else { " " }, 100.0);
+            bar = format!(
+                "{bar} {}{:3.0}%",
+                if percent > 100.0 { ">" } else { " " },
+                100.0
+            );
         } else {
             bar = format!("{bar}{percent:5.1}%");
         }
@@ -104,11 +123,9 @@ pub fn string_value_to_float(s: &str) -> Option<f64> {
     let mut digits = String::new();
     let mut rest = String::new();
     for c in cleaned.chars() {
-        if c.is_ascii_digit() || c == '.' {
-            if rest.is_empty() {
-                digits.push(c);
-                continue;
-            }
+        if (c.is_ascii_digit() || c == '.') && rest.is_empty() {
+            digits.push(c);
+            continue;
         }
         rest.push(c);
     }
@@ -195,7 +212,9 @@ pub fn py_repr(value: &Value) -> String {
 pub fn as_f64(value: &Value) -> Option<f64> {
     match value {
         Value::Number(n) => n.as_f64(),
-        Value::Bool(_) | Value::Null | Value::String(_) | Value::Array(_) | Value::Object(_) => None,
+        Value::Bool(_) | Value::Null | Value::String(_) | Value::Array(_) | Value::Object(_) => {
+            None
+        }
     }
 }
 
@@ -242,7 +261,10 @@ pub fn split_esc(input: &str, sep: char, esc: char) -> Vec<String> {
 /// shell by adding a `$` prefix in front of them. (Only the replacement
 /// flavour is needed by the plugins.)
 pub fn replace_special_chars(input: &str, by: char) -> String {
-    input.replace("\r\n", &by.to_string()).replace('\n', &by.to_string()).replace('\t', &by.to_string())
+    input
+        .replace("\r\n", &by.to_string())
+        .replace('\n', &by.to_string())
+        .replace('\t', &by.to_string())
 }
 
 #[cfg(test)]