API
#stringsString helpers. Read-only functions take &string so the caller keeps the source. Search uses Horspool. Includes Builder / Reader / Replacer.
index_ofpub fn index_of(s &string, sub string) intByte index of the first occurrence of sub in s. Empty sub returns 0; not found returns -1. Search uses Horspool.
s &stringsub stringfirst index, or -1 if missing; empty sub yields 0
containspub fn contains(s &string, sub string) boolWhether s contains substring sub. An empty sub is treated as contained (index 0).
s &stringsub stringtrue if found, else false
trim_spacepub fn trim_space(s &string) stringStrip leading and trailing ASCII whitespace.
s &stringstring — result string
repeatpub fn repeat(s &string, n int) stringRepeat the content n times; n<=0 yields empty.
s &stringn intstring — result string
joinpub fn join(parts []string, sep string) stringJoin parts with sep. An empty slice yields the empty string.
parts []stringsep stringthe joined string
splitpub fn split(s &string, sep string) []stringSplit s on sep. An empty sep does not split into bytes; the result is a one-element slice holding all of s.
s &stringsep string[]string parts (including a trailing empty piece when s ends with sep)
has_prefixpub fn has_prefix(s &string, pre string) boolWhether s starts with pre.
s &stringpre stringtrue if it does
has_suffixpub fn has_suffix(s &string, suf string) boolWhether s ends with suf.
s &stringsuf stringtrue if it does
ends_withpub fn ends_with(s &string, suf string) boolWhether s ends with suf (same idea as has_suffix).
s &stringsuf stringtrue if it does
replacepub fn replace(s &string, old string, new string, n int) stringReplace old with new in s. n==0 or empty old returns s unchanged; n<0 replaces all; n>0 replaces at most n times.
s &stringold stringnew stringn inta new string
fieldspub fn fields(s &string) []stringSplit on whitespace runs and drop the whitespace.
s &string[]string — slice result
fields_funcpub fn fields_func(s &string, f fn(int) bool) []stringFieldsFunc: separator is any Unicode rune for which f returns true.
s &stringf fn(int) bool[]string — slice result
to_lowerpub fn to_lower(s &string) stringMap ASCII letters to lowercase.
s &stringstring — result string
to_upperpub fn to_upper(s &string) stringMap ASCII letters to uppercase.
s &stringstring — result string
trim_leftpub fn trim_left(s &string, cutset string) stringStrip leading bytes that appear in the cutset.
s &stringcutset stringstring — result string
trim_rightpub fn trim_right(s &string, cutset string) stringStrip trailing bytes that appear in the cutset.
s &stringcutset stringstring — result string
trimpub fn trim(s &string, cutset string) stringStrip leading and trailing bytes that appear in the cutset.
s &stringcutset stringstring — result string
trim_prefixpub fn trim_prefix(s &string, pre string) stringRemove prefix if present; otherwise return the input.
s &stringpre stringstring — result string
trim_suffixpub fn trim_suffix(s &string, suf string) stringRemove suffix if present; otherwise return the input.
s &stringsuf stringstring — result string
comparepub fn compare(a &string, b &string) intLexicographic compare: -1, 0, or 1.
a &stringb &stringint — -1 if less, 0 if equal, 1 if greater
index_bytepub fn index_byte(s &string, c int) intIndex of the first byte c; -1 if missing.
s &stringc intint — index; -1 if missing
last_indexpub fn last_index(s &string, sub string) intIndex of the last occurrence; -1 if missing. Returns -1 if not found.
s &stringsub stringint — index; -1 if missing
last_index_bytepub fn last_index_byte(s &string, c int) intIndex of the last byte c; -1 if missing.
s &stringc intint — index; -1 if missing
countpub fn count(s &string, sub string) intNon-overlapping count of sub in s. Empty sub returns 1+s.len.
s &stringsub stringoccurrence count
split_npub fn split_n(s &string, sep string, n int) []stringSplit on the separator, at most n parts.
s &stringsep stringn int[]string — slice result
replace_allpub fn replace_all(s &string, old string, new string) stringReplace every occurrence of the substring.
s &stringold stringnew stringstring — result string
equal_foldpub fn equal_fold(a &string, b &string) boolASCII case-insensitive equality.
a &stringb &stringbool — true or false
struct Cutpub struct Cut {
pub before string
pub after string
pub found bool
}Public struct `Cut`.
before stringafter stringfound boolcutpub fn cut(s &string, sep string) CutCut into before/after at the first sep.
s &stringsep stringCut — a value of this type
cut_prefixpub fn cut_prefix(s &string, pre string) CutCut off a prefix when present.
s &stringpre stringCut — a value of this type
cut_suffixpub fn cut_suffix(s &string, suf string) CutCut off a suffix when present.
s &stringsuf stringCut — a value of this type
struct Builderpub struct Builder {
pub buf string
}Public struct `Builder`.
buf stringbuilderpub fn builder() Builderbuilder; returns Builder.
none
Builder — a value of this type
(&mut Builder) write_stringpub fn (b &mut Builder) write_string(s &string) intMethod on `&mut Builder`: write a string and return the byte count.
b &mut Builders &stringint — bytes written
(&mut Builder) growpub fn (b &mut Builder) grow(n int)Method on `&mut Builder`: ensure room for at least n more bytes.
b &mut Buildern int(&mut Builder) write_viewpub fn (b &mut Builder) write_view(s &string, v ByteView) intMethod on `&mut Builder`: write view.
b &mut Builders &stringv ByteViewint — a value of this type
(&mut Builder) write_intpub fn (b &mut Builder) write_int(n int) intMethod on `&mut Builder`: write int.
b &mut Buildern intint — a value of this type
(&Builder) lengthpub fn (b &Builder) length() intMethod on `&Builder`: return the current length.
b &Builderint — a value of this type
(&Builder) textpub fn (b &Builder) text() stringMethod on `&Builder`: return the current text.
b &Builderstring — result string
(&mut Builder) resetpub fn (b &mut Builder) reset()Method on `&mut Builder`: clear internal state so the value can be reused.
b &mut Builderindex_funcpub fn index_func(s &string, f fn(int) bool) intIndexFunc callbacks receive runes; results are byte offsets. MapBytes deliberately keeps its byte callback and byte result contract. Returns -1 if not found.
s &stringf fn(int) boolint — index; -1 if missing
last_index_funcpub fn last_index_func(s &string, f fn(int) bool) intLast index where the callback is true; -1 if missing. Returns -1 if not found.
s &stringf fn(int) boolint — index; -1 if missing
map_bytespub fn map_bytes(s &string, f fn(int) int) stringMap each byte through f and rebuild the string.
s &stringf fn(int) intstring — result string
struct ByteBuilderpub struct ByteBuilder {
pub buf []int
pub len int
}growable byte buffer for hot concat paths (compiler / fmt).
buf []intlen intnew_byte_builderpub fn new_byte_builder(cap int) ByteBuilderConstruct byte builder.
cap intByteBuilder — a value of this type
(&mut ByteBuilder) reservepub fn (sb &mut ByteBuilder) reserve(extra int)Call `reserve` on `&mut ByteBuilder`.
sb &mut ByteBuilderextra int(&mut ByteBuilder) write_bytepub fn (sb &mut ByteBuilder) write_byte(c int)Method on `&mut ByteBuilder`: write one byte.
sb &mut ByteBuilderc int(&mut ByteBuilder) write_strpub fn (sb &mut ByteBuilder) write_str(s string)Method on `&mut ByteBuilder`: write a string.
sb &mut ByteBuilders string(ByteBuilder) to_stringpub fn (sb ByteBuilder) to_string() stringMethod on `ByteBuilder`: convert to string.
sb ByteBuilderstring — result string
clonepub fn clone(s &string) stringstrings Clone / IndexAny / SplitAfter / TrimFunc / ToValidUTF8 Builder.WriteByte / WriteRune. Cutsets operate on Unicode runes.
s &stringstring — result string
contains_funcpub fn contains_func(s &string, f fn(int) bool) boolReport whether any byte satisfies the callback.
s &stringf fn(int) boolbool — true or false
index_anypub fn index_any(s &string, chars string) intIndex of the first byte that appears in the cutset; -1 if missing. Returns -1 if not found.
s &stringchars stringint — index; -1 if missing
last_index_anypub fn last_index_any(s &string, chars string) intLast index of any cutset byte; -1 if missing. Returns -1 if not found.
s &stringchars stringint — index; -1 if missing
contains_anypub fn contains_any(s &string, chars string) boolReport whether any byte from the cutset occurs.
s &stringchars stringbool — true or false
index_runepub fn index_rune(s &string, r int) intIndex of the first rune; -1 if missing. Returns -1 if not found.
s &stringr intint — index; -1 if missing
contains_runepub fn contains_rune(s &string, r int) boolReport whether the rune occurs.
s &stringr intbool — true or false
split_afterpub fn split_after(s &string, sep string) []stringSplit after the separator, keeping it on each piece.
s &stringsep string[]string — slice result
split_after_npub fn split_after_n(s &string, sep string, n int) []stringSplit after the separator, at most n parts.
s &stringsep stringn int[]string — slice result
trim_left_funcpub fn trim_left_func(s &string, f fn(int) bool) stringTrim leading bytes using the callback.
s &stringf fn(int) boolstring — result string
trim_right_funcpub fn trim_right_func(s &string, f fn(int) bool) stringTrim trailing bytes using the callback.
s &stringf fn(int) boolstring — result string
trim_funcpub fn trim_func(s &string, f fn(int) bool) stringTrim bytes on both ends using the callback.
s &stringf fn(int) boolstring — result string
to_valid_utf8pub fn to_valid_utf8(s &string, replacement string) stringReplace invalid UTF-8 sequences with replacement.
s &stringreplacement stringstring — result string
(&mut Builder) write_bytepub fn (b &mut Builder) write_byte(c int) intMethod on `&mut Builder`: write one byte.
b &mut Builderc intint — bytes written
(&mut Builder) write_runepub fn (b &mut Builder) write_rune(r int) intMethod on `&mut Builder`: write a rune as UTF-8.
b &mut Builderr intint — bytes written
(&Builder) cappub fn (b &Builder) cap() intMethod on `&Builder`: return the capacity.
b &Builderint — a value of this type
struct Replacerpub struct Replacer {
}strings.Replacer. Pairs are old/new; earlier pair wins when several match at the same index (not longest-first). Empty old inserts between bytes and at both ends, same as genericReplacer. No WriteString (no io.Writer). Odd argument count throws.
none
new_replacerpub fn new_replacer(oldnew <-> string) ReplacerConstruct replacer. Throws on failure.
oldnew <-> stringReplacer — a value of this type
(&Replacer) replacepub fn (r &Replacer) replace(s0 &string) stringReplace old with new in s. n==0 or empty old returns s unchanged; n<0 replaces all; n>0 replaces at most n times.
r &Replacers0 &stringa new string
struct Readerpub struct Reader {
}strings.Reader. read_n / read_at return owning strings (no []byte). read_n is empty at EOF (no throw); read_byte / read_rune throw "EOF". Invalid UTF-8 in read_rune is U+FFFD + 1 byte ( DecodeRuneInString). seek whence: 0 start / 1 current / 2 end. No WriteTo.
none
struct RuneReadpub struct RuneRead {
pub ch int
pub size int
}Public struct `RuneRead`.
ch intsize intnew_readerpub fn new_reader(s string) ReaderConstruct reader.
s stringReader — a value of this type
(&Reader) sizepub fn (r &Reader) size() intMethod on `&Reader`: return the size.
r &Readerint — a value of this type
(&Reader) lengthpub fn (r &Reader) length() intMethod on `&Reader`: return the current length.
r &Readerint — a value of this type
(&mut Reader) resetpub fn (r &mut Reader) reset(s string)Method on `&mut Reader`: clear internal state so the value can be reused.
r &mut Readers string(&mut Reader) read_npub fn (r &mut Reader) read_n(n int) stringMethod on `&mut Reader`: read at most n bytes; may return shorter or empty at end.
r &mut Readern intstring — result string
(&mut Reader) read_bytepub fn (r &mut Reader) read_byte() intMethod on `&mut Reader`: read one byte; throws on failure. Throws on failure.
r &mut Readerint — a value of this type
(&mut Reader) unread_bytepub fn (r &mut Reader) unread_byte() intMethod on `&mut Reader`: unread the last byte. Throws on failure.
r &mut Readerint — a value of this type
(&mut Reader) read_runepub fn (r &mut Reader) read_rune() RuneReadMethod on `&mut Reader`: read one UTF-8 rune. Throws on failure.
r &mut ReaderRuneRead — a value of this type
(&mut Reader) unread_runepub fn (r &mut Reader) unread_rune() intMethod on `&mut Reader`: unread the last rune. Throws on failure.
r &mut Readerint — a value of this type
(&mut Reader) seekpub fn (r &mut Reader) seek(offset int, whence int) intMethod on `&mut Reader`: move the read position. whence 0/1/2 = absolute / relative / from end. Throws on failure.
r &mut Readeroffset intwhence intint — a value of this type
(&mut Reader) read_atpub fn (r &mut Reader) read_at(n int, off int) stringMethod on `&mut Reader`: read at most n bytes starting at offset off. Throws on failure.
r &mut Readern intoff intstring — result string
struct ByteViewpub struct ByteView {
pub off int
pub len int
}ByteView is a read-only window [off, off+len) into a borrowed string. Xu has no user-visible pointers, so the (ptr,len) pair is (`s`, view). Indexing past the window is loud OOB (same as `s[s.len]`).
off intlen intview_ofpub fn view_of(s &string) ByteViewView of.
s &stringByteView — a value of this type
view_slicepub fn view_slice(s &string, off int, n int) ByteViewView slice.
s &stringoff intn intByteView — a value of this type
(&ByteView) atpub fn (v &ByteView) at(s &string, i int) intCall `at` on `&ByteView`.
v &ByteViews &stringi intint — a value of this type
(&ByteView) equalpub fn (v &ByteView) equal(s &string, t &string, w ByteView) boolMethod on `&ByteView`: report whether the two values are equal.
v &ByteViews &stringt &stringw ByteViewbool — true or false
(&ByteView) comparepub fn (v &ByteView) compare(s &string, t &string, w ByteView) intMethod on `&ByteView`: lexicographic compare: -1, 0, or 1.
v &ByteViews &stringt &stringw ByteViewint — -1 if less, 0 if equal, 1 if greater
(&ByteView) index_bytepub fn (v &ByteView) index_byte(s &string, c int) intMethod on `&ByteView`: index of the first byte c; -1 if missing. Returns -1 if not found.
v &ByteViews &stringc intint — index; -1 if missing
(&ByteView) last_index_bytepub fn (v &ByteView) last_index_byte(s &string, c int) intMethod on `&ByteView`: index of the last byte c; -1 if missing. Returns -1 if not found.
v &ByteViews &stringc intint — index; -1 if missing
(&ByteView) has_prefixpub fn (v &ByteView) has_prefix(s &string, pre &string) boolWhether s starts with pre.
v &ByteViews &stringpre &stringtrue if it does
(&ByteView) has_suffixpub fn (v &ByteView) has_suffix(s &string, suf &string) boolWhether s ends with suf.
v &ByteViews &stringsuf &stringtrue if it does
(&ByteView) indexpub fn (v &ByteView) index(s &string, sub &string) intIndex of `sub` relative to the window. Empty needle matches at 0. Returns -1 if not found.
v &ByteViews &stringsub &stringint — index; -1 if missing