fix string comparison functions

builtin/string.v

@@ -169,37 +169,35 @@ fn (s string) ne(a string) bool {
 	return !s.eq(a)
 }
 
-// s >= a
-fn (s string) ge(a string) bool {
-	mut j := 0
+// s < a
+fn (s string) lt(a string) bool {
 	for i := 0; i < s.len; i++ {
-		if i >= a.len {
-			return true
-		}
-		if int(s[i]) < int(a[j]) {
+		if i >= a.len || s[i] > a[i] {
 			return false
 		}
-		else if int(s[i]) > int(a[j]) {
+		else if s[i] < a[i] {
 			return true
 		}
-		j++
 	}
-	return true
+	if s.len < a.len {
+		return true
+	}
+	return false
 }
 
 // s <= a
 fn (s string) le(a string) bool {
-	return !s.ge(a) || s == a
-}
-
-// s < a
-fn (s string) lt(a string) bool {
-	return s.le(a) && s != a
+	return s.lt(a) || s.eq(a)
 }
 
 // s > a
 fn (s string) gt(a string) bool {
-	return s.ge(a) && s != a
+	return !s.le(a)
+}
+
+// s >= a
+fn (s string) ge(a string) bool {
+	return !s.lt(a)
 }
 
 // TODO `fn (s string) + (a string)` ? To be consistent with operator overloading syntax.

builtin/string_test.v

@@ -32,16 +32,59 @@ fn test_compare() {
 	assert b.ge(a)
 }
 
+fn test_lt() {
+	a := ''
+	b := 'a'
+	c := 'a'
+	d := 'b'
+	e := 'aa'
+	f := 'ab'
+	assert a.lt(b)
+	assert b.lt(c) == false
+	assert c.lt(d)
+	assert d.lt(e) == false
+	assert c.lt(e)
+	assert e.lt(f)
+}
+
+fn test_ge() {
+	a := 'aa'
+	b := 'aa'
+	c := 'ab'
+	d := 'abc'
+	e := 'aaa'
+	assert b.ge(a)
+	assert c.ge(b)
+	assert d.ge(c)
+	assert c.ge(d) == false
+	assert e.ge(a)
+}
+
+fn test_compare_strings() {
+	a := 'aa'
+	b := 'aa'
+	c := 'ab'
+	d := 'abc'
+	e := 'aaa'
+	assert compare_strings(a, b) == 0
+	assert compare_strings(b, c) == -1
+	assert compare_strings(c, d) == -1
+	assert compare_strings(d, e) == 1
+	assert compare_strings(a, e) == -1
+	assert compare_strings(e, a) == 1
+}
+
 fn test_sort() {
 	mut vals := [
-	'src', 'Music', 'go'
+		'arr', 'an', 'a', 'any'
 	]
 	len := vals.len
 	vals.sort()
 	assert len == vals.len
-	assert vals[0] == 'Music'
-	assert vals[1] == 'go'
-	assert vals[2] == 'src'
+	assert vals[0] == 'a'
+	assert vals[1] == 'an'
+	assert vals[2] == 'any'
+	assert vals[3] == 'arr'
 }
 
 fn test_split() {
@@ -247,4 +290,3 @@ fn test_all_after() {
 	q := s.all_after('fn ')
 	assert q == 'hello'
 }
-