ref: 64789fb5dcf8326f14f13d69a2576ae3aa2bbbaa
parent: 32d4bf68da7d16302f138dde343c70f9667933c4
author: Cameron Moore <moorereason@gmail.com>
date: Fri Nov 27 18:43:01 EST 2020
tpl: Refactor and fix substr logic Fix miscalculations when start is negative. Results should now match PHP substr. Fixes #7993
--- a/tpl/strings/strings.go
+++ b/tpl/strings/strings.go
@@ -279,64 +279,73 @@
// if length is given and is negative, then that many characters will be omitted from
// the end of string.
func (ns *Namespace) Substr(a interface{}, nums ...interface{}) (string, error) {- aStr, err := cast.ToStringE(a)
+ s, err := cast.ToStringE(a)
if err != nil {return "", err
}
+ asRunes := []rune(s)
+ rlen := len(asRunes)
+
var start, length int
- asRunes := []rune(aStr)
-
switch len(nums) {case 0:
- return "", errors.New("too less arguments")+ return "", errors.New("too few arguments")case 1:
if start, err = cast.ToIntE(nums[0]); err != nil {- return "", errors.New("start argument must be integer")+ return "", errors.New("start argument must be an integer")}
- length = len(asRunes)
+ length = rlen
case 2:
if start, err = cast.ToIntE(nums[0]); err != nil {- return "", errors.New("start argument must be integer")+ return "", errors.New("start argument must be an integer")}
if length, err = cast.ToIntE(nums[1]); err != nil {- return "", errors.New("length argument must be integer")+ return "", errors.New("length argument must be an integer")}
default:
return "", errors.New("too many arguments")}
- if start < -len(asRunes) {+ if rlen == 0 {+ return "", nil
+ }
+
+ if start < 0 {+ start += rlen
+ }
+
+ // start was originally negative beyond rlen
+ if start < 0 {start = 0
}
- if start > len(asRunes) {- return "", fmt.Errorf("start position out of bounds for %d-byte string", len(aStr))+
+ if start > rlen-1 {+ return "", fmt.Errorf("start position out of bounds for %d-byte string", rlen)}
- var s, e int
- if start >= 0 && length >= 0 {- s = start
- e = start + length
- } else if start < 0 && length >= 0 {- s = len(asRunes) + start - length + 1
- e = len(asRunes) + start + 1
- } else if start >= 0 && length < 0 {- s = start
- e = len(asRunes) + length
- } else {- s = len(asRunes) + start
- e = len(asRunes) + length
+ end := rlen
+
+ if length < 0 {+ end += length
+ } else if length > 0 {+ end = start + length
}
- if s > e {- return "", fmt.Errorf("calculated start position greater than end position: %d > %d", s, e)+ if start >= end {+ return "", fmt.Errorf("calculated start position greater than end position: %d > %d", start, end)}
- if e > len(asRunes) {- e = len(asRunes)
+
+ if end < 0 {+ return "", nil
}
- return string(asRunes[s:e]), nil
+ if end > rlen {+ end = rlen
+ }
+
+ return string(asRunes[start:end]), nil
}
// Title returns a copy of the input s with all Unicode letters that begin words
--- a/tpl/strings/strings_test.go
+++ b/tpl/strings/strings_test.go
@@ -441,8 +441,11 @@
}{ {"abc", 1, 2, "bc"}, {"abc", 0, 1, "a"},- {"abcdef", -1, 2, "ef"},- {"abcdef", -3, 3, "bcd"},+ {"abcdef", -1, 2, "f"},+ {"abcdef", -3, 3, "def"},+ {"abcdef", -1, nil, "f"},+ {"abcdef", -2, nil, "ef"},+ {"abcdef", -3, 1, "d"}, {"abcdef", 0, -1, "abcde"}, {"abcdef", 2, -1, "cde"}, {"abcdef", 4, -4, false},@@ -480,12 +483,12 @@
}
if b, ok := test.expect.(bool); ok && !b {- c.Assert(err, qt.Not(qt.IsNil))
+ c.Assert(err, qt.Not(qt.IsNil), qt.Commentf("%v", test))continue
}
c.Assert(err, qt.IsNil)
- c.Assert(result, qt.Equals, test.expect)
+ c.Assert(result, qt.Equals, test.expect, qt.Commentf("%v", test))}
_, err = ns.Substr("abcdef")