strings: add find_between_pair (#13468)
parent
d25652fbcf
commit
80444c8ec4
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@ -11,3 +11,118 @@ pub fn random(n int) string {
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return tos(buf)
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}
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*/
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// find_between_pair_byte returns the string found between the pair of marks defined
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// by `start` and `end`.
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// As opposed to the `find_between`, `all_after*`, `all_before*` methods defined on the
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// `string` type, this function can extract content between *nested* marks in `input`.
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// If `start` and `end` marks are nested in `input`, the characters
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// between the *outermost* mark pair is returned. It is expected that `start` and `end`
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// marks are *balanced*, meaning that the amount of `start` marks equal the
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// amount of `end` marks in the `input`. An empty string is returned otherwise.
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// Using two identical marks as `start` and `end` results in undefined output behavior.
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// find_between_pair_byte is the fastest in the find_between_pair_* family of functions.
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// Example: assert strings.find_between_pair_byte('(V) (NOT V)',`(`,`)`) == 'V'
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// Example: assert strings.find_between_pair_byte('s {X{Y}} s',`{`,`}`) == 'X{Y}'
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pub fn find_between_pair_byte(input string, start byte, end byte) string {
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mut marks := 0
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mut start_index := -1
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for i, b in input {
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if b == start {
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if start_index == -1 {
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start_index = i + 1
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}
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marks++
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continue
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}
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if start_index > 0 {
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if b == end {
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marks--
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if marks == 0 {
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return input[start_index..i]
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}
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}
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}
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}
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return ''
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}
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// find_between_pair_rune returns the string found between the pair of marks defined
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// by `start` and `end`.
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// As opposed to the `find_between`, `all_after*`, `all_before*` methods defined on the
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// `string` type, this function can extract content between *nested* marks in `input`.
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// If `start` and `end` marks are nested in `input`, the characters
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// between the *outermost* mark pair is returned. It is expected that `start` and `end`
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// marks are *balanced*, meaning that the amount of `start` marks equal the
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// amount of `end` marks in the `input`. An empty string is returned otherwise.
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// Using two identical marks as `start` and `end` results in undefined output behavior.
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// find_between_pair_rune is inbetween the fastest and slowest in the find_between_pair_* family of functions.
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// Example: assert strings.find_between_pair_rune('(V) (NOT V)',`(`,`)`) == 'V'
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// Example: assert strings.find_between_pair_rune('s {X{Y}} s',`{`,`}`) == 'X{Y}'
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pub fn find_between_pair_rune(input string, start rune, end rune) string {
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mut marks := 0
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mut start_index := -1
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runes := input.runes()
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for i, r in runes {
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if r == start {
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if start_index == -1 {
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start_index = i + 1
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}
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marks++
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continue
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}
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if start_index > 0 {
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if r == end {
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marks--
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if marks == 0 {
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return runes[start_index..i].string()
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}
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}
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}
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}
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return ''
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}
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// find_between_pair_string returns the string found between the pair of marks defined
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// by `start` and `end`.
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// As opposed to the `find_between`, `all_after*`, `all_before*` methods defined on the
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// `string` type, this function can extract content between *nested* marks in `input`.
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// If `start` and `end` marks are nested in `input`, the characters
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// between the *outermost* mark pair is returned. It is expected that `start` and `end`
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// marks are *balanced*, meaning that the amount of `start` marks equal the
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// amount of `end` marks in the `input`. An empty string is returned otherwise.
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// Using two identical marks as `start` and `end` results in undefined output behavior.
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// find_between_pair_string is the slowest in the find_between_pair_* function family.
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// Example: assert strings.find_between_pair_string('/*V*/ /*NOT V*/','/*','*/') == 'V'
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// Example: assert strings.find_between_pair_string('s {{X{{Y}}}} s','{{','}}') == 'X{{Y}}'
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pub fn find_between_pair_string(input string, start string, end string) string {
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mut start_index := -1
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mut marks := 0
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start_runes := start.runes()
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end_runes := end.runes()
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runes := input.runes()
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mut i := 0
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for ; i < runes.len; i++ {
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start_slice := runes#[i..i + start_runes.len]
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if start_slice == start_runes {
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i = i + start_runes.len - 1
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if start_index < 0 {
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start_index = i + 1
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}
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marks++
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continue
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}
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if start_index > 0 {
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end_slice := runes#[i..i + end_runes.len]
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if end_slice == end_runes {
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marks--
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if marks == 0 {
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return runes[start_index..i].string()
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}
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i = i + end_runes.len - 1
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continue
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}
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}
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}
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return ''
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}
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@ -12,3 +12,85 @@ fn test_repeat_string() {
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assert strings.repeat_string('abc', 0) == ''
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assert strings.repeat_string('', 200) == ''
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}
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const test_rune_and_byte = [
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'xxx[ok1]xxx',
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'xxx[[ok2]okok]',
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'xxx[ok3[[[ok]okok]]]',
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'yyy[ok4]',
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'[]',
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']',
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'[',
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'yyy[ok5][]zzz',
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'yyy[xxx',
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'xxx[xxx
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xxx]',
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]
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const test_strings = [
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'xxx/*ok1*/xxx',
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'xxx/*/*ok2*/okok*/',
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'xxx/*ok3/*/*/*ok*/okok*/*/*/',
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'yyy/*ok4*/',
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'/**/',
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'*/',
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'/*',
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'yyy/*ok5*//**/zzz',
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'yyy/*xxx',
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'xxx/*xxx
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xxx*/xxx',
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]
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const expected_rune_and_byte_outputs = [
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'ok1',
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'[ok2]okok',
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'ok3[[[ok]okok]]',
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'ok4',
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'',
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'',
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'',
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'ok5',
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'',
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'xxx
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xxx',
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]
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const expected_string_outputs = [
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'ok1',
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'/*ok2*/okok',
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'ok3/*/*/*ok*/okok*/*/',
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'ok4',
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'',
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'',
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'',
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'ok5',
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'',
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'xxx
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xxx',
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]
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fn test_find_between_pair_family() {
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assert strings.find_between_pair_rune('xx♡ok❦yy', `♡`, `❦`) == 'ok'
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assert strings.find_between_pair_byte('xx{ok}yy', `{`, `}`) == 'ok'
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assert strings.find_between_pair_string('xx/*ok*/yy', '/*', '*/') == 'ok'
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assert strings.find_between_pair_byte('xx{ok}yy', `{`, `}`) == 'ok'
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assert strings.find_between_pair_string('xxxxokyyyy', 'xxx', 'yyy') == 'xok'
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for i, tstr in test_rune_and_byte {
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e1 := strings.find_between_pair_rune(tstr, `[`, `]`)
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e2 := expected_rune_and_byte_outputs[i]
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assert '$e1' == '$e2'
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}
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for i, tstr in test_rune_and_byte {
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e1 := strings.find_between_pair_byte(tstr, `[`, `]`)
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e2 := expected_rune_and_byte_outputs[i]
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assert '$e1' == '$e2'
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}
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for i, tstr in test_strings {
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e1 := strings.find_between_pair_string(tstr, '/*', '*/')
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e2 := expected_string_outputs[i]
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assert '$e1' == '$e2'
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}
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}
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