Ignore leading whitespaces when calculating 'begin' index

CHANGELOG.md

@@ -4,11 +4,12 @@ CHANGELOG
 0.11.2
 ------
 
-- `--tiebreak` now accepts comma-separated list of sort criteria.
+- `--tiebreak` now accepts comma-separated list of sort criteria
     - Each criterion should appear only once in the list
     - `index` is only allowed at the end of the list
     - `index` is implicitly appended to the list when not specified
     - Default is `length` (or equivalently `length,index`)
+- `begin` criterion will ignore leading whitespaces when calculating the index
 
 0.11.1
 ------

src/item.go

@@ -92,7 +92,14 @@ func (item *Item) Rank(cache bool) [5]int32 {
 			}
 		case byBegin:
 			// We can't just look at item.offsets[0][0] because it can be an inverse term
-			val = int32(minBegin)
+			whitePrefixLen := 0
+			for idx, r := range item.text {
+				whitePrefixLen = idx
+				if idx == minBegin || r != ' ' && r != '\t' {
+					break
+				}
+			}
+			val = int32(minBegin - whitePrefixLen)
 		case byEnd:
 			if prevEnd > 0 {
 				val = int32(1 + len(item.text) - prevEnd)

test/test_go.rb

@@ -605,6 +605,64 @@ class TestGoFZF < TestBase
     assert_equal by_begin_end, `#{FZF} -ffb --tiebreak=end,length < #{tempname}`.split($/)
   end
 
+  def test_tiebreak_white_prefix
+    writelines tempname, [
+      'f o o b a r',
+      '    foo bar',
+      '    foobar',
+      '----foo bar',
+      '----foobar',
+      '  foo bar',
+      '  foobar--',
+      '  foobar',
+      '--foo bar',
+      '--foobar',
+      'foobar',
+    ]
+
+    assert_equal [
+      '    foobar',
+      '  foobar',
+      'foobar',
+      '  foobar--',
+      '--foobar',
+      '----foobar',
+      '    foo bar',
+      '  foo bar',
+      '--foo bar',
+      '----foo bar',
+      'f o o b a r',
+    ], `#{FZF} -ffb < #{tempname}`.split($/)
+
+    assert_equal [
+      '    foobar',
+      '  foobar--',
+      '  foobar',
+      'foobar',
+      '--foobar',
+      '----foobar',
+      '    foo bar',
+      '  foo bar',
+      '--foo bar',
+      '----foo bar',
+      'f o o b a r',
+    ], `#{FZF} -ffb --tiebreak=begin < #{tempname}`.split($/)
+
+    assert_equal [
+      '    foobar',
+      '  foobar',
+      'foobar',
+      '  foobar--',
+      '--foobar',
+      '----foobar',
+      '    foo bar',
+      '  foo bar',
+      '--foo bar',
+      '----foo bar',
+      'f o o b a r',
+    ], `#{FZF} -ffb --tiebreak=begin,length < #{tempname}`.split($/)
+  end
+
   def test_tiebreak_length_with_nth
     input = %w[
       1:hell