Add exact size support to the --size filter (sharkdp#669)

doc/fd.1

@@ -179,6 +179,8 @@ Limit results based on the size of files using the format
 file size must be greater than or equal to this
 .IP '-'
 file size must be less than or equal to this
+.P
+If neither '+' nor '-' is specified, file size must be exactly equal to this.
 .IP 'NUM'
 The numeric size (e.g. 500)
 .IP 'UNIT'

src/app.rs

@@ -390,7 +390,8 @@ pub fn build_app() -> App<'static, 'static> {
                 .long_help(
                     "Limit results based on the size of files using the format <+-><NUM><UNIT>.\n   \
                         '+': file size must be greater than or equal to this\n   \
-                        '-': file size must be less than or equal to this\n   \
+                        '-': file size must be less than or equal to this\n\
+                     If neither '+' nor '-' is specified, file size must be exactly equal to this.\n   \
                         'NUM':  The numeric size (e.g. 500)\n   \
                         'UNIT': The units for NUM. They are not case-sensitive.\n\
                      Allowed unit values:\n    \

src/filter/size.rs

@@ -2,13 +2,14 @@ use lazy_static::lazy_static;
 use regex::Regex;
 
 lazy_static! {
-    static ref SIZE_CAPTURES: Regex = Regex::new(r"(?i)^([+-])(\d+)(b|[kmgt]i?b?)$").unwrap();
+    static ref SIZE_CAPTURES: Regex = Regex::new(r"(?i)^([+-]?)(\d+)(b|[kmgt]i?b?)$").unwrap();
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum SizeFilter {
     Max(u64),
     Min(u64),
+    Equals(u64),
 }
 
 // SI prefixes (powers of 10)
@@ -49,16 +50,19 @@ impl SizeFilter {
         };
 
         let size = quantity * multiplier;
-        Some(match limit_kind {
-            "+" => SizeFilter::Min(size),
-            _ => SizeFilter::Max(size),
-        })
+        match limit_kind {
+            "+" => Some(SizeFilter::Min(size)),
+            "-" => Some(SizeFilter::Max(size)),
+            "" => Some(SizeFilter::Equals(size)),
+            _ => None
+        }
     }
 
     pub fn is_within(&self, size: u64) -> bool {
         match *self {
             SizeFilter::Max(limit) => size <= limit,
             SizeFilter::Min(limit) => size >= limit,
+            SizeFilter::Equals(limit) => size == limit,
         }
     }
 }
@@ -170,7 +174,6 @@ mod tests {
 
     // Invalid parse data
     gen_size_filter_failure! {
-        ensure_missing_symbol_returns_none: "10M",
         ensure_missing_number_returns_none: "+g",
         ensure_missing_unit_returns_none: "+18",
         ensure_bad_format_returns_none_1: "$10M",

tests/tests.rs

@@ -1387,6 +1387,9 @@ fn test_size() {
 
     // Zero sized files.
     te.assert_output(&["", "--size", "-0B"], "0_bytes.foo");
+    te.assert_output(&["", "--size", "0B"], "0_bytes.foo");
+    te.assert_output(&["", "--size=0B"], "0_bytes.foo");
+    te.assert_output(&["", "-S", "0B"], "0_bytes.foo");
 
     // Files with 2 bytes or more.
     te.assert_output(
@@ -1403,6 +1406,9 @@ fn test_size() {
     // Files with size between 1 byte and 11 bytes.
     te.assert_output(&["", "--size", "+1B", "--size", "-11B"], "11_bytes.foo");
 
+    // Files with size equal 11 bytes.
+    te.assert_output(&["", "--size", "11B"], "11_bytes.foo");
+
     // Files with size between 1 byte and 30 bytes.
     te.assert_output(
         &["", "--size", "+1B", "--size", "-30B"],
@@ -1434,6 +1440,7 @@ fn test_size() {
 
     // Files with size equal 4 kibibytes.
     te.assert_output(&["", "--size", "+4ki", "--size", "-4ki"], "4_kibibytes.foo");
+    te.assert_output(&["", "--size", "4ki"], "4_kibibytes.foo");
 }
 
 #[cfg(test)]